Direct effects from
the closure
structures, including
impacts from
increases in turbidity.
Long-term impacts
from closure
structures include
fish movement and
increased predation.
Indirect effects to
fish habitat from
vegetation removal
and from vibration
during construction.
Direct effects from
the closure
structures, including
impacts from
increases in turbidity.
Long-term impacts
from closure
structures include
fish movement and
increased predation.
Indirect effects to
fish habitat from
vegetation removal
and from vibration
during construction.
Direct effects from
the closure
structures, including
impacts from
increases in turbidity.
Long-term impacts
from closure
structures include
fish movement and
increased predation.
Indirect effects to fish
habitat from vegetation
removal and from
vibration during
construction. Direct
effects from the closure
structures, including
impacts from increases in
turbidity. Long-term
impacts from closure
structures include fish
movement and increased
predation. Construction
of the Old Mormon
Channel bypass may
create a corridor for
migrating adult and
juvenile fish.
Indirect effects to fish
habitat from vegetation
removal and from
vibration during
construction. Direct
effects from the closure
structures, including
impacts from increases in
turbidity. Long-term
impacts from closure
structures include fish
movement and increased
predation. Construction
of the Old Mormon
Channel bypass may
create a corridor for
migrating adult and
juvenile fish.
Significance Too speculative for
meaningful
consideration.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation Compensation would
likely occur after the
fact but there would
still be significant
direct impacts due to
the loss of
vegetation.
A vegetation variance,
if approved, would
allow vegetation to
remain on the lower
waterside levee slope
and adjacent easement.
All disturbed lands
would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures
would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
A vegetation variance,
if approved, would
allow vegetation to
remain on the lower
waterside levee slope
and adjacent easement.
All disturbed lands
would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures
would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
A vegetation variance,
if approved, would
allow vegetation to
remain on the lower
waterside levee slope
and adjacent easement.
All disturbed lands
would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures
would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
A vegetation variance,
if approved, would
allow vegetation to
remain on the lower
waterside levee slope
and adjacent easement.
All disturbed lands
would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures
would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
A vegetation variance, if
approved, would allow
vegetation to remain on
the lower waterside levee
slope and adjacent
easement. All disturbed
lands would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures and
Old Mormon Channel
bypass would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
A vegetation variance, if
approved, would allow
vegetation to remain on
the lower waterside levee
slope and adjacent
easement. All disturbed
lands would be reseeded
following construction.
BMPs would be
implemented to address
turbidity. Design and
construction of the
closure structures and
Old Mormon Channel
bypass would be closely
coordinated with the
resource agencies to
avoid and minimize
impacts to fisheries.
Effect With
Mitigation
Not applicable. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
ATTACHMENT D 1001
Lower San Joaquin River
ES-24
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Special Status Species
Effect Flood event or flood
fight could cause loss
of habitat and fatality
to species.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Direct affects to GGS,
VELB, fish species, and
Swainson’s hawks
during construction.
Direct effects from
construction and
operation of closure
structures. Indirect
effects from vegetation
removal and vibration
during construction.
Significance Significant VELB and GGS:
Significant.
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS:
Significant
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS:
Significant
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS:
Significant
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS:
Significant
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS:
Significant
CV Steelhead,
Sacramento R winterrun Chinook salmon,
CV spring-run Chinook
salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
Conservation/
Mitigation
Measures
None available Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Implement BMPs
during construction.
Transplant elderberry
shrubs that cannot be
avoided. Replace
habitat for species
either on-site or in close
proximity to lost
habitat. Work with
resource agencies on
design and operational
criteria for the closure
structures. Obtain a
vegetation variance, if
appropriate.
Effect with
Conservation
and Mitigation
Measures
Significant VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
VELB and GGS: Less
than significant. CV
Steelhead, Sacramento
R winter-run Chinook
salmon, CV spring-run
Chinook salmon, Green
sturgeon, Delta smelt:
Significant and
unavoidable.
ATTACHMENT D 1002
Lower San Joaquin River
ES-25
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Socioeconomics and Environmental Justice
Effect Flooding of
residential areas and
displacement of
populations during a
flood event.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Disruption to residents
alongside construction
sites from traffic, noise,
and dust. Acquisition of
properties for
construction and flood
control easements.
Significance Too speculative for
meaningful
consideration.
Significant. Significant. Significant. Significant. Significant. Significant Mitigation None possible. Federal Relocation
Act compliance.
Federal Relocation
Act compliance.
Federal Relocation
Act compliance.
Federal Relocation
Act compliance.
Federal Relocation
Act compliance.
Federal Relocation
Act compliance.
Effect With
Mitigation
Not applicable. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant.
Land Use
Effect Inconsistent with local
land use policies
requiring the protection
of the existing urban
area from flood
damages. Potential for
induced growth in
RD17 consistent with
future growth plans of
the Cities of Stockton,
Lathrop and Manteca.
Acquisition of
properties for
construction and
flood control
easements along the
levees, floodwall,
and closure structures
in North and Central
Stockton. Permanent
loss of SRA.
Acquisition of
properties for
construction and flood
control easements along
the levees, floodwall,
and closure structures
in North and Central
Stockton and in RD17.
Potential for induced
growth with reduction
of flood risk in RD17.
Permanent loss of SRA.
Acquisition of
properties for
construction and
flood control
easements along the
levees, floodwall,
and closure structures
in North and Central
Stockton. Permanent
loss of SRA.
Acquisition of
properties for
construction and flood
control easements along
the levees, floodwall,
and closure structures
in North and Central
Stockton and in RD17.
Potential for induced
growth with reduction
of flood risk in RD17.
Permanent loss of SRA.
Acquisition of
properties for
construction and flood
control easements along
the levees, floodwall,
Old Mormon Channel
flood bypass, and
closure structures in
North and Central
Stockton and in RD17.
Potential for induced
growth with reduction
of flood risk in RD17.
Permanent loss of SRA.
Acquisition of
properties for
construction and flood
control easements along
the levees, floodwall,
Old Mormon Channel
flood bypass, and
closure structures in
North and Central
Stockton and in RD17.
Potential for induced
growth with reduction
of flood risk in RD17.
Permanent loss of SRA.
Significance Too speculative for
meaningful
consideration.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation None possible. Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Relocation
Assistance and Real
Property Acquisition
Polices Act of 1970
compliance.
Effect With
Mitigation
Not applicable. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
ATTACHMENT D 1003
Lower San Joaquin River
ES-26
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Transportation
Effect Potential for flooded
roadways and railroad
tracks in a flood event.
Damage to roadways
and railroad tracks from
flooding and cleanup.
Flood cleanup would
create large volumes of
truck traffic to remove
flood debris.
Temporary delays in
emergency response
time, temporary
railroad service
disruptions, hauling
materials through
residential
neighborhoods, and
school zones, and
potential interference
with evacuation routes
during construction.
Increased traffic on
public roadways
could potentially
cause delays.
Increased traffic on
public roadways
could potentially
cause delays.
Increased traffic on
public roadways
could potentially
cause delays.
Increased traffic on
public roadways
could potentially
cause delays.
Increased traffic on
public roadways
could potentially
cause delays.
Significance Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation None possible. Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Notification and
coordination with all
potentially affected
parties during PED, and
again before initiating
construction activities.
Before the start of each
construction season, the
primary construction
contractors would
develop a coordinated
construction traffic
safety and control plan.
The contractor would
be required to avoid
neighborhoods and
school zones to the
maximum extent
feasible when
determining haul
routes.
Effect With
Mitigation
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
ATTACHMENT D 1004
Lower San Joaquin River
ES-27
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Utilities and Public Services
Effect In a flood event there
could be significant
damage to utility
systems. Debris from
flooded homes and
properties could
overwhelm solid waste
disposal facilities.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Temporary
disruptions to utility
services possible,
particularly during
relocation of utilities
that penetrate the
levee.
Significance Too speculative for
meaningful
consideration.
Significant. Significant. Significant. Significant. Significant. Significant.
Mitigation None possible. Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Before beginning
construction,
coordination with
utility providers to
implement orderly
relocation of utilities.
Effect With
Mitigation
Not applicable. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant.
ATTACHMENT D 1005
Lower San Joaquin River
ES-28
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Recreation
Effect Damage to recreation
facilities during
flooding and
potential loss due to
erosion.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Temporary closure of
recreation facilities
along the San Joaquin
River, Calaveras River,
Smith Canal, French
Camp Slough,
Fourteenmile Slough,
Fivemile Slough,
Tenmile Slough, and
Mosher Creek during
construction. This
includes closure of bike
and walking trails, and
boat launches.
Temporary and long
term changes to
recreational boating
would result from the
closure of structures on
Smith Canal and
Fourteenmile Slough.
Long-term impacts to
passive recreation as a
result of vegetation
removal.
Significance Too speculative for
meaningful
consideration.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation None possible. Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Notification and
coordination with
recreation users,
boaters, and bike
groups. Flaggers,
signage, detours, and
fencing to notify and
control recreation
access and traffic
around construction
sites. Compensatory
plantings, as feasible.
Effect With
Mitigation
Not applicable. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
ATTACHMENT D 1006
Lower San Joaquin River
ES-29
Final Feasibility Report – January 2018
San Joaquin County, CA Executive Summary
Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Aesthetics
Effect A flood event would
damage the visual
character in the study
area.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton.
Floodwall and closure
structure at Smith Canal
in Central Stockton.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton and in
RD17. Floodwall and
closure structure at
Smith Canal in Central
Stockton.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton.
Floodwall and closure
structure at Smith Canal
in Central Stockton.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton and in
RD17. Floodwall and
closure structure at
Smith Canal in Central
Stockton.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton.
Floodwall and closure
structure at Smith Canal
in Central Stockton.
Vegetation loss and
construction activities
would disrupt the
existing visual
conditions along the
levees in North and
Central Stockton and in
RD17. Floodwall and
closure structure at
Smith Canal in Central
Stockton.
Significance Less than significant. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation None possible. If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
If a variance to the
Vegetation ETL is
approved, fewer trees
and shrubs would be
removed and some
replacement plantings
could be provided onsite. Where feasible,
appropriate trees and
shrubs would be
planted on the landside
of the levees outside of
the 15 foot no
vegetation zone.
Disturbed areas would
be reseeded with native
grasses.
Effect With
Mitigation
Less than significant. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
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Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Noise
Effect Increased noise
during flood fighting
and reconstruction.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Increased noise and
vibration in
proximity to sensitive
receptors due to
construction
activities.
Significance Less than significant. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation Not applicable. Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Coordination with
local residents,
compliance with
noise ordinances, and
BMPs.
Effect With
Mitigation
Not applicable. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
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Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Public Health and Environmental Hazards
Effect Flooding could
release potential
household and
industrial chemicals
and cause damage to
sewage treatment
plants.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Potential release of
hazardous chemicals
used on the
construction site.
Encountering HTRW
sites during
construction.
Significance Too speculative for
meaningful
consideration.
Less than significant. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant.
Mitigation None possible. Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Implement a SWPPP,
BSSCP, and SPCCP to
avoid accidental spills
and releases into the
environment. Known
HTRW sites within the
construction footprint
would be removed and
properly disposed of
prior to construction.
HTRW sites
encountered during
construction would be
removed and properly
disposed of. Borrow
material would be
tested prior to use to
ensure that no
contaminated soils are
used for this project.
Effect With
Mitigation
Not applicable. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant. Less than significant.
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Resource
Alternative 1
No Action Alternative 7a Alternative 7b Alternative 8a Alternative 8b Alternative 9a Alternative 9b Cultural Resources
Effect Damage to historic
and prehistoric
resources during a
flood event.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, and closure
structures.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, and closure
structures.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, and closure
structures.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, and closure
structures.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, closure
structures, and a
flood bypass.
Adverse effects to
cultural resource and
to historic properties
from construction of
levee improvements,
new levees, seepage
berms, closure
structures, and a
flood bypass.
Significance Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Mitigation None possible. Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Preparation and
implementation of a
Programmatic
Agreement, Historic
Properties
Management Plan,
and Historic
Properties Treatment
Plans.
Effect With
Mitigation
Not applicable. Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
Significant and
unavoidable.
ATTACHMENT D 1010
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ATTACHMENT D 1011
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CHAPTER 1 — STUDY INFORMATION
PURPOSE AND NEED FOR THE PROJECT AND REPORT
The purpose of the Lower San Joaquin River Feasibility Study (LSJRFS) is to investigate the extent of Federal interest in a range of alternative plans to reduce flood risk in the cities of Stockton, Lathrop, Manteca and surrounding urbanizing areas (study area). The objective of the non-Federal Sponsors (NFS), who are the Central Valley Flood Protection Board (CVFPB) and the San Joaquin Area Flood Control Agency (SJAFCA), is to meet the requirements of California Senate Bill 5 (SB 5) of 2007, the Central Valley Flood Improvement Act, to achieve a 200-year level of protection for urban and urbanizing areas.
The Federal and non-Federal objectives for the study are discussed in Chapter 2 , Sections 2.2.1 and 2.2.2, respectively. The NFS is responsible for demonstrating compliance with State of California requirements for any proposed project resulting from this study. The study area experienced major floods in 1955, 1958, and 1997, resulting in varying degrees of damage. Modeling of climate change for the Central Valley forecasts more frequent, short duration, high flow events that could potentially increase future flood risk.
The existing levee system protects over 71,000 acres of mixed-use land, about 235,000 people and an estimated $28.7 billion in damageable property.
INTEGRATED REPORT
This is an integrated Feasibility Report/Environmental Impact Statement/Environmental Impact Report (FR/EIS/EIR) that describes the planning process and analyses used to identify the Recommended Plan (RP). This FR/EIS/EIR: (1) describes the flood risk in the cities of Stockton, Lathrop, Manteca and surrounding unincorporated areas; (2) evaluates a range of alternatives to reduce flood risk, including potential environmental impacts; (3) describes measures to minimize or mitigate for potential environmental impacts; (4) identifies a RP for implementation; (5) describes coordination, consultation and public involvement; and (6) describes compliance with Federal and State laws, Executive Orders and other requirements.
NEPA AND CEQA
This FR/EIS/EIR evaluates the potential environmental impact of the alternatives and proposes mitigation measures including avoidance, minimization and compensation to reduce, where feasible, any significant and/or potentially significant adverse impacts. The US Army Corps of Engineers (USACE) is the NEPA Federal Lead Agency. SJAFCA is the CEQA lead agency. On January 15, 2010, USACE published a Notice of Intent (NOI) to prepare an EIS for the LSJRFS in the Federal Register (Vol. 75, No. 10) and SJAFCA filed a Notice of Preparation (NOP) with the State Clearinghouse.
SCOPE OF ENVIRONMENTAL ANALYSIS
The FR/EIS/EIR documents the analyses undertaken in the Feasibility Study to consider the level of Federal participation in Flood Risk Management (FRM) for the overall defined study area. The environmental effects of the proposed alternatives are analyzed using a conservative approach that looks at typical cross sections and footprints for levee reaches. This is considered reasonable and appropriate given the current status of project planning and design and available information and data. The impact analysis conservatively assumes the most expansive construction footprint; in other words, the impacts discussed herein should be the greatest potential impacts associated with the proposed alternatives. As planning proceeds, USACE and the NFS will continue to refine project elements, construction methods, equipment types and construction schedules to further reducing adverse impacts.
If the RP is authorized and funding is appropriated by Congress, USACE and the NFS would begin ATTACHMENT D 1012
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Preconstruction Engineering and Design phase (PED), which allows for design refinements based on the most current information. Any refinements to project elements that occur during PED or construction will be reviewed and compared to what was evaluated in this FR/EIS/EIR to determine if supplemental NEPA and/or CEQA documentation will be required. The scope of the FR/EIS/EIR includes evaluation of Federal interest in addressing seepage, slope stability, erosion and height concerns of the levees surrounding North and Central Stockton and RD17.
INTENDED USES OF THIS DOCUMENT
This FR/EIS/EIR recommends a plan to reduce flood risk to the study area and discloses potential impacts of the project alternatives. Impacts are determined by projecting the environmental conditions in the future with and without the project. This document also presents measures that could be implemented to avoid, reduce and/or compensate for potential environmental impacts. This FR/EIS/EIR will be circulated for a 30-day State and Agency Review. USACE Headquarters will review this report and prepare a report from the Chief of Engineers (Chief’s Report). After review by the Office of the Assistant Secretary of the Army (Civil Works) and the Office of Management and Budget (OMB), the Chief’s Report will be transmitted to Congress for potential project authorization and to allow appropriation of funds toward the Federal share of construction costs.
STUDY AUTHORITY
The general authority for flood control investigations in the San Joaquin River Basin arises under the Flood Control Act of 1936 (Public Law [PL] 74-738), Sections 2 and 6 and amended by the Flood Control Act of 1938 (PL 75-761). Further studies of the river system were requested in the May 8, 1964 resolution adopted by the Committee on Public Works of the House of Representatives. The resolution reads:
“Resolved by the Committee on Public Works of the House of Representatives, United States, that the Board of Engineers for Rivers and Harbors is hereby requested to review the reports on the SacramentoSan Joaquin Basin Streams, California, published in House Document No. 367, 81st Congress, 1st session and other reports, with a view to determine whether any modifications to the recommendations contained therein are advisable at this time, with particular reference to further coordinated development of the water resources in the San Joaquin River Basin, California.”
The LSJRFS is in accordance with Section 905(b) Analysis (Water Resources Development Act (WRDA) 1986) dated 23 September 2004, approved by the South Pacific Division (SPD) Commander, on June 10, 2005. The Section 905(b) Analysis was prepared with funds identified in House Report 108-357 (Conference Report to accompany H.R. 2745 for the Energy and Water Development Appropriations Act of 2004) for use under the Sacramento-San Joaquin River Basins Comprehensive Study to evaluate ER, FRM and related purposes for the Lower San Joaquin River (LSJR). House Report 105-190, which accompanied the Energy and Water Development Appropriations Act of 1998 (PL 105-62), identified initial funding and directed USACE to conduct a Comprehensive Study.
The Section 905(b) Analysis determined that there were potential FRM and ER projects in the LSJR area.
This study focuses on FRM through additional scoping and coordination with the NFS, resource agencies and local stakeholders.
This study partially addresses the Sacramento–San Joaquin Basin Streams, California Comprehensive Study authority. Therefore, the LSJRFS will be called an “Interim Feasibility Report” to indicate the study ATTACHMENT D 1013
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is addressing the flood risk issues of a specific area within the authority, rather than the entire authorized area. This report does not rule out additional studies for this or other areas, including RD 17, within the authorized study area at a future date.
ATTACHMENT D 1014
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Figure 1-1: Study Authority Extent
ATTACHMENT D 1015
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PROJECT LOCATION, STUDY AREA AND PROJECT AREA
PROJECT LOCATION AND STUDY AREA
The study area is located along the lower (northern) portion of the San Joaquin River system in the Central Valley of California (Figure 1-1). The San Joaquin River originates on the western slope of the Sierra Nevada and emerges from the foothills at Friant Dam. It flows west to the Central Valley, where it is joined by the Fresno, Chowchilla, Merced, Tuolumne, Stanislaus and Calaveras Rivers and smaller tributaries as it flows north to the Sacramento-San Joaquin Delta (Delta). The study area includes the mainstem of the San Joaquin River from the Mariposa Bypass downstream to the city of Stockton. It also includes the distributary channels of the San Joaquin River in the southernmost reaches of the Delta: Paradise Cut and Old River and as far north as Tracy Boulevard, Middle River and Victoria Canal. Based on coordination with local interests, the study area initially included the Littlejohn Creek and Farmington Dam southeast of Stockton, Lathrop and Manteca; the city of Stockton extending from the Calaveras River, Mormon Channel and Bear Creek; and tributaries north of Stockton, including the Lodi waste water treatment plant at Thornton Road and Interstate 5 (Figure 1-2).
During scoping for the study, two potential sponsors were identified, the SJAFCA and the CVFPB. In collaboration with the NFS the study area was reduced to Stockton, Lathrop, Manteca and the surrounding urbanizing area (Figure 1-3). The reduced area encompasses 305 square miles, including the aforementioned incorporated areas and unincorporated portions of San Joaquin County.
During the plan formulation process, 15,000 acres of urban, urbanizing and agricultural lands were screened out due to lack of Federal interest and concerns with enabling development of undeveloped areas. The screening was consistent with Executive Order 11988, Floodplain Management. The remaining study area was divided into three separable elements (North Stockton, Central Stockton and Reclamation District (RD)
17. The separable elements are hydraulically separate, meaning that each area could have unique standalone solutions or alternatives proposed that would have no flood risk effect on adjacent areas.
PROJECT AREA
For the purpose of NEPA and CEQA, the “project area” is the footprint of the project where direct physical disturbance would occur. For the final array of alternatives evaluated in the impact analysis, this mainly includes existing levees and lands immediately adjacent to the levees. For all of the alternatives, the project area also includes portions of Fourteenmile Slough and Smith Canal, where in-water closure structures would be constructed. For two of the alternatives (Alternatives 9a and 9b) the “project area” would also include the Old Mormon Channel.
Mormon Slough’s course extends in a general southwesterly direction from Bellota to the Stockton Diverting Canal flow diversion structure, which diverts all flood flows to the diverting canal that discharges into the Calaveras River. The Mormon Slough below the diverting dam is referred to locally as Mormon Channel. The source of flow in Mormon Channel is the local tributary area downstream of the diversion structure.
ATTACHMENT D 1016
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Figure 1-2: Study Area
ATTACHMENT D 1017
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Figure 1-3: Lower San Joaquin River Feasibility Study Area ATTACHMENT D 1018
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STUDY SPONSORS AND PARTICIPANTS
The NFS are SJAFCA and the State of California, represented by the CVFPB and supported by DWR.
SJAFCA has local cooperation agreements with 11 Urban RDs (RD 2042, Bishop Tract; RD 2126, Atlas Tract; RD 2115, Shima Tract; RD 1608, Smith Tract; RD 2074, Sargent Barhardt Tract; RD 1614, Smith Tract; RD 828, Weber Tract; RD 404, Boggs Tract; RD 403, Rough and Ready Island; RD 17, Mossdale Tract; RD 2062, Stewart Tract), the Cities of Lodi, Stockton, Manteca, Lathrop and San Joaquin County.
HISTORY OF LOWER SAN JOAQUIN RIVER INVESTIGATIONS
The following USACE reports were reviewed as a part of this study:
Reference Major Points
Lower San Joaquin
River and Tributaries
Authorized by the Flood Control Act of 1944 and construction initiated in 1956, with various modifications made through the mid-1980’s.
The Federally-constructed portion of the project consists of 100 miles of intermittent levees along the San Joaquin River downstream of the Merced River, as well as along Paradise Cut, Old River, Camp Slough and the lower reaches of the Stanislaus and Tuolumne Rivers (Figure 1-3). The levees vary in height from 15 feet at the downstream end to an average of 6 to 8 feet over much of the project length.
The project also included construction of New Hogan Dam on the Calaveras River, New Melones Dam on the Stanislaus River and Old Don Pedro Dam on the Tuolumne River.
The Chowchilla and Eastside Bypasses were constructed by the State as part of the project. The project levees, along with upstream regulation, were designed to contain floods varying from once in 60 years probability at the lower end of the project to once in 100 years at the upper limits.
Over the 60-year period since the project was authorized, the estimated level of performance of the project was reduced by changes in the hydrologic record, settlement, erosion, extensive sediment deposition, and establishment of vegetation between the levees despite maintenance efforts. The project cannot be maintained as originally envisioned due to newer environmental constraints.
San Joaquin River and
Kings River, North
Interim Flood Control
Study, 1985
A reconnaissance study of flooding along the San Joaquin from Friant Dam and the Kings River from Stinson Weir, downstream to near Stockton, was initiated in 1984. It focused on sediment and vegetation removal to increase channel capacity.
Study terminated in 1985 when no economically-justified solutions for additional FRM were identified.
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Reference Major Points
Draft General Design
Memorandum and
Environmental
Statement, Lower San
Joaquin River and
Tributaries, California;
Clearing and Snagging,
January 1987
The Supplemental Appropriations Act of 1983 (PL 98-63) modified the completed Lower San Joaquin River and Tributaries project to include an additional $5 million for clearing and snagging on the San Joaquin River from Stockton upstream to Friant Dam.
A draft General Design Memorandum was prepared by the USACE in 1987 to implement the authorized work, which was increased to $8 million by the Energy and Water Development Appropriations Act of 1988 (HR 100-2700). No economic benefit analysis was conducted.
The USACE plan included habitat mitigation, but environmental objections couldn’t be resolved and the project wasn’t implemented.
Reconnaissance Report,
San Joaquin River
Mainstem, California,
January 1993
Focused on FRM and ER problems along the mainstem of the San Joaquin River in coordination with the San Joaquin River Management Program.
Plans included various combinations of floodwater diversions to wildlife refuges, agricultural lands, and other private lands, channel and levee improvements, and restoration of riparian and wetland habitats.
The channel and levee improvements primarily consisted of removing aggraded sediment and vegetation from the channel and adding toe drains and berms to address seepage problems.
One potentially justified, multiple-purpose plan consisting of diversion of floodwaters to three habitat restoration areas and restoration of 172 acres of riparian and shaded riverine aquatic habitat between River Miles 63 and 70 was identified. The three areas were the China Island Unit of the California Department of Fish and Game’s North Grasslands Wildlife Area (3,300 acres), the Arena Plains National Wildlife Refuge and nearby conservation easement lands (11,500 acres) and 3,890 acres of lands within the Grasslands Water District. The plan would have created 5,580 acres of new wetlands, 840 acres of new riparian habitat, and 110 acres of new aquatic habitat at an estimated first cost of $44 million (1993 price level). FRM benefits were low, but exceeded separable FRM costs, indicating that a multiple-purpose project may be economically justified under current USACE policy.
The study did not go beyond the reconnaissance phase due to lack of non-Federal funding.
Post-Flood Assessment,
Sacramento and San
Joaquin River Basins,
California, March 1999
Part of the Energy and Water Development Appropriations Act of 1998 that focused on the impact of major floods in 1983, 1986, 1995, and 1997, including maps of flooded areas and estimates of economic damages.
Described the development of flood protection in the Central Valley during the past 150 years, including major facilities, their operating objectives, and constraints.
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Reference Major Points
Sacramento and San
Joaquin Comprehensive
Study Interim Report,
December 2002
Federal and State legislation authorized the development of comprehensive plans for FRM and ER along the Sacramento and San Joaquin Rivers in January 1997.
The study developed analytical tools to evaluate how changes to the system would affect performance as a whole with respect to flood risk and degraded ecosystems.
A comprehensive solution will require measures that increase conveyance capacity, increase flood storage, and improve floodplain management and levee reliability.
It provides a way to develop projects that ensures system-wide effects are evaluated regardless of project scale, and an administrative structure to oversee processes.
Factors to develop and implement in future projects are: use a science-based adaptive assessment and management approach to measure success and improve future project planning; continued coordination with resource management programs; complete a series of technical studies; consider potential climate changes; periodically update system-wide information; and use a scientific peer review process.
West Bear Creek
Transitory Storage
Would restore transient storage of peak flood flows on the west side of the San Joaquin River near the Bear Creek confluence, including portions of the West Bear Creek and Freitas Units of the San Luis National Wildlife Refuge and Great Valley Grasslands State Park.
Evaluated removal of non-Federal levee on the left bank of the San Joaquin River, or regulated inflows at three locations along the levee. FRM and ER benefits could be achieved at a lower cost by breaching the levee in several spots rather than removing it.
The project would increase the frequency of inundation for 1,500 to 2,000 acres of floodplain habitats. Approximately 260 to 300 acres of grassland would be converted to wetland and riparian forest/scrub-shrub habitats, supporting a greater diversity and higher population of special status species.
Results suggested that additional flood attenuation could be achieved by connecting the Mud Slough and Salt Slough flood basins upstream of San Joaquin River and including the East Bear Creek Unit.
Central Valley Basins
Enhanced Flood
Response and
Emergency Preparedness
Developed a plan to increase the effectiveness of existing flood response and emergency preparedness systems to prepare, forecast, and warn residents of impending flooding from the Sacramento and San Joaquin Rivers and their tributaries.
Of several alternatives, the most favorable provided incremental improvements to existing data collection and management, flood detection, and notification and decisionmaking systems.
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EXISTING PROGRAMS, STUDIES AND PROJECTS
PROGRAMS
Federal Emergency Management Agency (FEMA), Flood Mitigation Assistance Program and the Hazard Mitigation Grant Program
These programs seek to reduce or eliminate loss of life and property damage due to natural and humancaused hazards. In order to qualify for these programs, a community must be enrolled in the National Flood Insurance Program (NFIP) and have a Flood Mitigation Plan approved by the FEMA Regional Director.
This plan must include a description of the existing flood hazard and flood risk, including estimates of the number and type of structures at risk, repetitive loss properties and the extent of flood depth and damage potential. A project must be cost-effective, not costing more than the anticipated value of the reduction in both direct damages and subsequent negative impacts to the area if future flooding were to occur, computed on a net present value basis. Applicants for these programs must compete for funding. The Cities of Stockton, Lathrop and Manteca are enrolled in the NFIP. San Joaquin County’s enrollment covers the unincorporated areas, which includes the study area outside the cities’ limits.
Designated Floodway Program
The CVFPB administers the Designated Floodway Program for California, which addresses land use management within the floodway. This program provides a nonstructural way to keep development from encroaching into flood-prone areas and reduces future potential flood damages by preserving the reasonable flood passage capacities of natural watercourses. The CVFPB adopts floodway boundaries, develops plans for modifications of boundaries and approves changes in acceptable use and types of structures within the floodways. Designated Floodway refers to the channel of the stream and that portion of the adjoining floodplain reasonably required for the passage of a design flood; it is also the floodway between existing levees as adopted by the CVFPB (formerly the Reclamation Board) or the Legislature. Floodway areas in the study area are primarily limited to the areas between levees.
Central Valley Flood Protection Plan (CVFPP)
The CVFPB approved the CVFPP (administered by DWR) in July 2012. SB 5 required that DWR and CVFPB address flooding problems in the Central Valley (Sacramento-San Joaquin Valley) and report to the Legislature with updates every 5 years. In response to SB 5, the State initiated the CVFPP to develop a comprehensive approach to FRM and related problems. SB 5 further requires local flood management agencies to achieve a “200-year urban level of flood protection” for urban or urbanizing areas of greater than 10,000 people, or meet the FEMA standard for rural, non-urbanized areas by 2025” for further development to be permitted in those areas. The CVFPP proposed a State-wide investment approach for improving the State-Federal FRM system to meet the new standard, while addressing ecosystem and other water related objectives. This approach permits modification or improvement of existing facilities of the State Plan of Flood Control (SPFC), construction of new facilities and opportunities for ecosystem improvements within the SPFC. The State is conducting basin-wide feasibility studies for the Sacramento River and San Joaquin River Basins. The conceptual proposals of the 2012 CVFPP are being further evaluated for technical and economic feasibility in the basin-wide studies. The results of various planning efforts by local interests have been evaluated by DWR for inclusion in the CVFPP 2017 update recently submitted to the CVFPB for approval. Further evaluations will continue and will be reported in the CVFPP 2022 update.
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PROJECTS
Development of water resources in the basin began in the 1850s and currently includes large, multiplepurpose reservoirs, extensive levee and channel improvements, bypasses and local diversion canals (USACE, 1993). Many agencies were involved in water resource development within the study area, including USACE, United States Bureau of Reclamation (USBR), State of California, county irrigation districts, local reclamation districts and local levee districts.
Design flows for FRM projects within the study area are provided in Table 1-1. Reservoir projects upstream of the study area with dedicated, Federally authorized FRM space are listed in Table 1-2 and shown in Figure 1-1.
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Table 1-1: Project Design Flood Flows
Reach
Design
Flow
(cfs)*
Design
Freeboard
(feet) Source
Mormon Slough
Bellota to Potter Creek 12,500 3 with levee
1.5 w/o levee
USACE,
1974
Potter Creek to Diverting Canal 13,500 3 with levee
1.5 w/o levee
USACE,
1974
Stockton Diverting Canal
Mormon Slough to Calaveras River 13,500 3 USACE,
1974
Lower Calaveras River
Diverting Canal to San Joaquin River 13,500 3 USACE,
1974
Potter Creek
Jack Tone Road to Mormon Slough 1000
San Joaquin River
Stanislaus River to Paradise Dam (at head of
Paradise Cut) 52,000 3 USACE, 1993
Paradise Dam to Old River 37,000** 3 USACE,
1963
Old River to French Camp Slough 22,000 3 USACE,
1963
French Camp Slough to Stockton Deep Water Ship
Channel 18,000 3 USACE, 1963
French Camp Slough
French Camp turnpike to San Joaquin River 3000 3
Duck Creek
Duck Creek Diversion to Mariposa Road 700 Not Available USACE, 1967
Mariposa Road to French Camp Slough 900 Not Available USACE, 1967
Bear Creek***
Highway 99 to Western Pacific Railroad 5,500 3 USACE,
1963
Western Pacific Railroad to Pixley Slough 6,350 3 USACE, 1963
Pixley Slough to San Joaquin River 7,060 3 USACE,
1963
* - cfs = cubic feet per second
** - Design diversion capacity of Paradise Cut is 15,000 cfs *** - Change in design flows by WRDA 2007 per revised Operations and Maintenance Manual, Federal Project levee ends at Disappointment Slough (4000 feet downstream of Pixley Slough)
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Table 1-2: Reservoirs with Dedicated FRM Storage, San Joaquin River Basin Reservoir Owner
Year
Constructed
Objective
Flow
(cfs)
Objective Flow
Location
Gross Pool
Storage
(ac-ft)
Max
Dedicated
Flood
Space
(ac-ft)
Friant USBR 1942 8,000
6,500
Little Dry Creek
at Mendota Gage 520,500 170,000
Big Dry Creek FMFCD 1948 700 Wasteway 30,200 30,200
Farmington USACE 1951 2,000 Town of
Farmington 52,000 52,000
Camanche EBMUD 1963 5,000 Below Dam 430,900 200,000
New Hogan USACE 1963 12,500 at Bellota 317,100 165,000
Los Banos USBR 1965 1,000 Los Banos 34,600 14,000
New
Exchequer
Merced
ID 1967 6,000 Cressey 1,024,600 350,000
Don Pedro Turlock
ID 1971 9,000 Modesto 2,030,000 340,000
Buchanan USACE 1975 7,400
7,000
Below Dam
Chowchilla River
at Madera
150,000 45,000
Hidden USACE 1975 5,000 at Medara Canal 90,000 65,000
New Melones USBR 1979 8,000 Orange Blossom 2,400,000 450,000 U.S. Fish and Wildlife Service. San Joaquin River National Wildlife Refuge This refuge, established in 1987 under authority of the ESA, the Land and Water Conservation Fund Act and the Migratory Bird Conservation Act, is located within the historic floodplain of the confluences of the San Joaquin, Stanislaus and Tuolumne Rivers and downstream of the confluence with Orestimba Creek.
Refuge lands consist of oak-cottonwood-willow riparian forest, pastures, agricultural fields and wetlands.
The original refuge land base of 1,638 acres has grown through recent land acquisitions to 6,642 acres, within an approved refuge boundary of 12,877 acres.
U.S. Fish and Wildlife Service. San Luis National Wildlife Refuge This 26,609-acre refuge is a mix of managed seasonal and permanent wetlands, a riparian habitat associated with three major watercourses and native grasslands/alkali sinks/vernal pools. It is primarily managed to provide habitats for migratory and wintering birds. The largest concentration of mallards, pintails and green-winged teal in the San Joaquin Valley are found here. One of only 22 herds of the indigenous Tule elk is located here, as are a variety of endangered, threatened and sensitive species.
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U.S. Department of Agriculture, Natural Resource Conservation Service Wetland Reserve Program The Natural Resource Conservation Service’s Wetlands Reserve Program focuses on the restoration of a variety of wetland types throughout the State, including seasonal wetlands, semi-permanent marshes and vernal pools along the perimeter of the Central Valley, riparian corridors and tidally-influenced wetlands.
The program has been used to restore land along the San Joaquin River that has experienced flooding.
Central Valley Project Improvement Act (CVPIA)
The Central Valley Project (CVP) was authorized by Congress in 1937 as a multipurpose development to store and transfer surplus water primarily from the Sacramento and Trinity River Basins, to the waterdeficient lands of the San Joaquin River and Tulare Lake Basins. The project is operated by USBR. The CVPIA amended the CVP to include fish and wildlife protection, restoration and mitigation, having equal priority with irrigation and domestic water supply uses, fish and wildlife enhancement and power generation. The CVPIA gives first priority to measures that protect and restore natural channel and riparian habitat values.
STUDIES
Delta Islands and Levees Feasibility Study: USACE and DWR are assessing ER and FRM problems and opportunities in the Delta area. A Draft Integrated FR/EIS, released for public review in April 2014, tentatively recommended 90 acres of intertidal marsh restoration in the central Delta. Pending reviews, the report will be finalized as an interim feasibility report that will make recommendations on construction projects and/or additional studies for authorization by Congress. Delta Long-Term Management Strategy: USACE, DWR, the California Bay-Delta Authority, the Delta Protection Commission, the State Water Resources Control Board (SWRCB) and the Central Valley RWQCB are developing a long-term management strategy for sediment management in the Delta, including dredging and dredged material placement and reuse. San Francisco Bay to Stockton Navigation Improvement Project: USACE, the Port of Stockton and Contra Costa County Water Agency are evaluating the efficiency of the movement of goods along the existing deep draft navigation route extending from the San Francisco Bay to the Port of Stockton. The project includes the John F. Baldwin and Stockton Ship Channels.
EXISTING PROJECTS DIRECTLY AFFECTED BY THE STUDY
There are three existing authorized projects covering portions of the levees being examined:
The Calaveras River levees are components of the Mormon Slough Project as authorized by the Flood Control Act of 1962 (PL 874, October 23, 1962, 87th Congress, 2nd Session). The French Camp Slough right bank levee to the east of Interstate 5 is a component of the Duck Creek Project as authorized by Section 205 of the 1948 Flood Control Act as amended by Public Law 685, 84th Congress, 2nd Session.
The San Joaquin River right bank levees along RD 404 are part of the Lower San Joaquin River and Tributaries Project as authorized by the Flood Control Act of 1944 (PL 534, December 22, 1944, 78th Congress, 2nd Session), as modified by PL 327, 84th Congress, 1st Session).
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Current O&M responsibilities are as follows:
Mormon Slough Project: SJAFCA and CVFPB
Duck Creek Project: San Joaquin County Flood Control & Water Conservation District Lower San Joaquin River and Tributaries Project: CVFPB
ENVIRONMENTAL REGULATORY FRAMEWORK
NEPA
NEPA provides an interdisciplinary framework for Federal agencies to develop information that will help them to take environmental factors into account in their decision-making (42 USC Section 4321, 40 CFR Section 1500.1). According to NEPA, an EIS is required whenever a proposed major Federal action (e.g., a proposal for legislation or an activity financed, assisted, conducted, or approved by a Federal agency) would result in significant effects on the quality of the natural and human environment. A “cooperating agency" is defined in NEPA regulations as any Federal agency, other than a lead agency, that has jurisdiction by law or special expertise with respect to any environmental impact involved in a proposed project or project alternative. A State or local agency of similar qualifications or, when the effects are on lands of tribal interest, a Native American tribe may, by agreement with the lead agencies, also become a cooperating agency (40 CFR 1508.5). For the LSJRFS, CVFPB, DWR and SJAFCA are cooperating agencies under NEPA.
CEQA
According to the State CEQA Guidelines (Section 15064[f][1]), preparation of an EIR is required whenever a project may result in a significant environmental impact. An EIR is an informational document used to inform public agency decision makers and the general public of the significant environmental effects of a project, identify possible ways to mitigate or avoid the significant effects and describe a range of reasonable alternatives to the project that could feasibly attain most of the basic objectives of the project while substantially lessening or avoiding any of the significant environmental impacts. Public agencies are required to consider the information presented in the EIR when determining whether to approve a project.
CEQA requires that State and local government agencies consider the environmental effects of projects over which they have discretionary authority before taking action on those projects (California Public Resources Code [PRC] Section 21000 et seq.). CEQA also requires that each public agency avoid or reduce to less-than-significant levels, wherever feasible, the significant environmental effects of projects it approves or implements. If a project would result in significant environmental impacts that cannot be feasibly mitigated to less-than-significant levels, the project can still be approved, but the lead agency’s decision makers must issue a “statement of overriding considerations” explaining in writing the specific economic, social, or other considerations that they believe, based on substantial evidence, make those significant and unavoidable effects acceptable.
For the purposes of CEQA, Responsible Agencies are those public agencies, other than the Lead Agency, that have discretionary approval power over the project (CEQA Guidelines Section 15381). These agencies are required to rely on the Lead Agency’s environmental document in acting on whatever aspect of the project requires their approval, but must prepare and issue their own findings regarding the project (State CEQA Guidelines Section 15096). Trustee Agencies are those that have jurisdiction over certain resources held in trust for the people of California but do not have legal authority over approving or carrying out the project. For the LSJR Project, CVFPB is a Responsible Agency under CEQA. Responsible and Trustee Agencies for the project are identified in Table 1-3.
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Table 1-3: Responsible and Trustee Agencies (CEQA)
Agency Jurisdiction
California Department of Fish and Wildlife Fish and wildlife Native plants designated as rare or endangered
Game refuges
Ecological reserves
California Department of Conservation Williamson Act lands California State Lands Commission State-owned “sovereign” lands Responsible Agency
U.S. Environmental Protection Agency NEPA and Clean Water Act coordination U.S. Fish and Wildlife Service Fish and wildlife and Endangered Species Act National Marine Fisheries Service Anadromous fish and Endangered Species Act U.S. Department of Agriculture Prime farmland conversion California Department of Fish and Wildlife Fish and wildlife Native plants designated as rare or endangered
Game refuges
Ecological reserves
Office of Historic Preservation Historic and cultural resources Central Valley Flood Protection Board Levee modifications California Air Resources Board Air quality
Regional Water Quality Control Board Water quality and discharges to water bodies California Department of Water Resources State water and flood management interests San Joaquin County/State Mining and Geology
Board
Surface mining and reclamation activities
associated with borrow
City of Stockton Land use designations
City of Lathrop Land use designations
City of Manteca Land use designations
Reclamation District 17 Levee operation and maintenance Reclamation District 404 Levee operation and maintenance RDs 1604, 2074, 1608, 1614, 828 Levee operation and maintenance
REPORT ORGANIZATION
The organization and chapter headings in this FR/EIS/EIR reflect both the plan formulation process and environmental documentation requirements. The headings corresponding to sections required by NEPA in an EIS are noted with an asterisk (*). Several chapters also relate to the six steps of the USACE planning process.
The first chapter, Study Information, introduces the study, discusses the purpose and need*, authority, study area, NFS and previous investigations covering the LSJR area. The integrated nature of the report is also explained.
The second chapter, Need and Objectives for Action, covers the first step in planning (specification of water and land resources problems and opportunities).
The third chapter, Plan Formulation, covers formulation of alternatives, comparison of alternative plans and selection of the RP based upon the comparison of the alternative plans.
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The fourth chapter, Description of Final Alternatives*, provides a detailed description of the final alternative plans, including the no action alternative. This includes the purpose and construction details of the various measures, as well as the locations and specific measures included in each of the final alternatives.
The fifth chapter, Affected Environment and Environmental Consequences, describes the existing resources in the study area and evaluates the effects and significance of the final alternatives on those resources.
Avoidance, minimization and mitigation measures are also proposed to reduce any effects to less than significant. The chapter covers inventory, forecast and analysis of water and land resources in the study area and an evaluation of the effects of the alternative plans.
The remaining chapters of the report discuss public involvement, review and consultation (Chapter 6); describe compliance with applicable laws, policies and plans (Chapter 7); describe the RP (Chapter 8); present the final study recommendations (Chapter 9); list the recipients* of the FR/EIS/EIR (Chapter 10); list the report preparers (Chapter 11); amd list the references (Chapter 12). A list of acronyms and abbreviations precedes Chapter 1.
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CHAPTER 2 — NEED AND OBJECTIVES FOR ACTION
PROBLEMS AND OPPORTUNITIES
A problem is an existing undesirable condition to be changed. An opportunity is a chance to create a future condition that is desirable. Within the context of solving problems, opportunities contribute to the overall beneficial outcome of the project. The difference between problems and opportunities is often indistinct, but in both cases a changed future condition is preferred. The feasibility study identifies, evaluates and recommends to decision makers an appropriate, coordinated and implementable solution to the identified water and land resources problems and opportunities for the LSJRFS area. The following key problems were identified during the planning process by the study team and concerned stakeholders.
FLOODING
Problem: There is significant risk to public health, safety and property in the study area associated with flooding.
The study area is located in the Central Valley of California which has very little topographic relief, resulting in potential flooding of areas far from water courses (Figure 2-1). Due to the flat topography, the study area is prone to deep flooding as demonstrated for a 0.2% annual chance exceedance (ACE) event (Figure 2-2). Flow monitoring data has been collected for the San Joaquin River since around 1930 at the Vernalis gage site (Figure 2-3). The flow data shows several significant flow events, the most recent in 1997. Major events occurred three times since the 1950s. The 1955 event had the highest flows recorded on the Calaveras River at Bellota and 1,500 acres of Stockton were inundated to depths of six feet for as long as eight days (Figure 2-4). The 1958 event inundated 8,500 acres between Bellota and the Diverting Canal with flood waters up to two feet deep and inundation durations from two to 10 days. The 1997 event resulted in the evacuation of the Weston Ranch area of Stockton at the north end of RD 17. While the 1997 event did not directly damage areas of Stockton, Lathrop or Manteca, there were 1,842 residences and businesses affected in San Joaquin and Stanislaus Counties. There were also significant flood-fighting efforts conducted during the 1997 event in RDs 404 and 17. Between the two RDs, there were 37 sites flood-fought. Damages in San Joaquin County for the 1997 event were estimated to be near $80 million.
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Figure 2-1: Topography of Lower San Joaquin River Floodplain ATTACHMENT D 1031
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Figure 2-2: 0.2% Median ACE Floodplain
For explanation of Figure 2-2 Risk and Uncertainty criteria dictate whether or not a breach occurs at an index point (red dots or circles). Breach simulation is shown if the levee does not pass assurance criteria described in Engineer Circular (EC) 1110-2-6067. Assurance is defined as the probability that a target stage will not be exceeded during the occurrence of a specified flood. The value may include geotechnical failure considerations. This term is also referred to as Conditional Non-Exceedance Probability. Levees identified in the figure are based on the California Levee Database (CLD) and National Levee Database (NLD).
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Figure 2-3: Peak Annual Flows from USGS Gage at Vernalis ATTACHMENT D 1033
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Figure 2-4: Flooding Looking West Across the South Stockton Area (1955) ATTACHMENT D 1034
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Figure 2-5: Study Area Levees
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The primary risk of flooding in the study area is geotechnical failure of the existing levees and not hydrologic or hydraulic factors that result in levee overtopping. Recent geotechnical analysis and evaluation of historical performance during past flood events have resulted in a greater understanding of underseepage and a revision of levee design criteria. Geomorphologic and geotechnical studies identified subsurface features, such as former river channels and meanders. The potential for seepage to occur along the existing levees is created by discontinuous layers of coarse‐grained pervious soils (i.e., sands and gravels) found at varying depths of up to 100 feet. During high water events, river water can enter the pervious soil layers and then move laterally under/through the levee. Excessive seepage can erode soil within the levee and lead to a rapid collapse and subsequent breach. Historically, foundation conditions were evaluated assuming homogeneous materials, but the floods of 1986 and 1997 and the resulting levee failures throughout the Central Valley resulted in a revision of the criteria for the evaluation of underseepage. The risk of levee failure is not due to design deficiency or to lack of O&M of the existing levees, but to a better understanding of the mechanics of underseepage in the Central Valley. The levees within the study area do not meet current USACE levee design criteria and are at risk of breach failure at stages considerably less than levee crest elevations. This is evidenced by historical levee boils and heavy seepage at river stages less than design flows. Proposed project modifications will address the improved understanding of system performance effects of through and under-seepage while returning the levee system to compliance with authorized performance criteria.
Geotechnical related issues such as underseepage breach failures result in large volume flood flows at high velocities that are sudden and unpredictable. These failures have minimal warning and minimal time for effective implementation of evacuation and emergency plans. Study area flood events generally occur during the winter months when colder air and water temperatures significantly increase the risk of death by exposure. The risk probability of unexpected levee failure coupled with the consequence of basin‐wide flooding presents a continued threat to public safety, property and critical infrastructure in the LSJR basin.
Table 2-1: Structures Located within the 1/500 ACE Floodplain Economic Impact
Area Residential Commercial Industrial Public
Total
Structures
Rural 1,921 25 23 10 1,979
Urban 73,391 2,865 888 513 77,657
Total 75,312 2,890 911 523 79,636
Table 2-2: Value of Damageable Property within the 1/500 ACE Floodplain ($1,000s) October 2017 Price Levels
Land Use
Structural Value Content Value
Rural Urban Rural Urban Total
Residential 311,072 8,756,577 311,073 8,743,882 18,122,604 Commercial 81,471 2,456,836 49,729 1,809,298 4,397,334
Industrial 99,458 1,777,556 112,155 2,078,047 4,067,216 Public 16,929 835,874 7,406 393,602 1,253,811
Autos 20,103 836,932 0 0 857,035
Total 529,033 14,663,775 480,363 13,024,829 28,698,000
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Development is expected to continue within the study area, which could increase the number of structures and people at risk of flooding. These expectations are supported by the Stockton, Lathrop and Manteca General Plans, which specifically identify planned development, including infill of previously developed urban areas as well as conversion of agricultural lands to urban land use. Such development in RD 17 potentially doubles the number of structures at risk and increases population risk by 45,000 to 50,000 persons based on adopted and approved land use plans. It is unknown whether or not development and population growth would meet these projections during the 50-year planning horizon for this study and what effect the passage of SB 5 will have on these growth estimates.
OPPORTUNITIES
Opportunity: Improve FRM in the study area.
There is an opportunity to reduce the risk to public safety and flood damages from the Calaveras and San Joaquin Rivers, Mosher Slough and the Delta.
Opportunity: Sustain and improve aquatic, riparian and adjacent terrestrial habitats in conjunction with FRM features.
There is an opportunity to sustain and improve floodplain habitats along existing water courses in conjunction with FRM features.
Opportunity: Integration with other Federal, State and local initiatives.
There is an opportunity to integrate a proposed project with other watershed-level initiatives for a holistic approach to FRM, ER and navigation in the San Joaquin River watershed.
Opportunity: Educate the public about residual flood risk.
There is an opportunity to expand current programs and continue to educate the public about ongoing residual flood risk.
OBJECTIVES AND CONSTRAINTS
FEDERAL OBJECTIVES
In the Flood Control Act of 1970, Congress identified four equal national objectives in water resources development planning. These objectives are: NED, Regional Economic Development (RED), Environmental Equality (EQ) and Social Wellbeing and Other Social Effects (OSE). These four categories are known as the System of Accounts, whereby each proposed plan can be easily compared to the no action plan and other alternatives. The Federal objective identified in the Economic and Environmental Principles for Water and Related Land Resources Implementation Studies (Principles and Guidelines) of February 3, 1983 (42 U.S.C. 1962 a-2 and d-1), is:
“The Federal objective of water and related land resources planning is to contribute to national economic development consistent with protecting the Nation’s environment, pursuant to national environmental statues, applicable Executive Orders and other Federal planning requirements.” ATTACHMENT D 1037
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NON-FEDERAL OBJECTIVES
The NFS objective is to identify and evaluate FRM alternatives to determine an implementable plan, in cooperation with USACE, to reduce the flood risk to people, property and infrastructure. SB 5 requires the sponsor to identify, develop, and construct a plan that will perform at a level sufficient to withstand flooding that has a 1-in-200 chance of occurring in any given year using criteria consistent with, or developed by, the Department of Water Resources.
PLANNING OBJECTIVES
The national objective to contribute to NED is a general statement and not specific enough for direct use in plan formulation. The water and related land resource problems and opportunities identified are refined and stated as specific planning objectives to provide focus for the formulation of alternatives. These planning objectives reflect the problems and opportunities and represent desired positive changes in the withoutproject conditions. Each of the planning objectives applies to the study area for the 50-year period of analysis, except where stated otherwise. The planning objectives are as follows:
Reduce risk to property and infrastructure due to flooding in Stockton, Lathrop and Manteca (NED Account);
Reduce flood risk to public health, safety and life in Stockton, Lathrop and Manteca (OSE Account); Minimize residual flood risks to the extent justified; and Incorporate environmentally sustainable design principles during development and analysis of FRM plan components.
PLANNING CONSTRAINTS
Planning constraints represent restrictions that are important to various stakeholders. Some constraints are absolute and represent restrictions that should be observed (e.g., existing regulations and law). Other constraints are more flexible and can be incorporated into the tradeoff analysis. The planning constraints are:
Minimize significant adverse impacts to the human environment; and Comply with applicable Federal laws, regulations and policies.
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INVENTORY AND FORECAST OF FUTURE WITHOUT PROJECT CONDITIONS The future without-project (FWOP) is the most likely condition expected to exist in the future in the absence of a proposed water resource project. The FWOP defines the benchmark against which the alternative plans are evaluated. While most of the documentation of the inventory and forecast of affected resources is located in Chapter 5, a few critical assumptions that affect plan formulation are highlighted in this section.
Critical assumptions in defining the FWOP conditions include:
Residents of Stockton, Lathrop and Manteca will continue to live in historically modified floodplain areas and be at risk of flood events.
There are three populations at risk in the study area:
Population flooded: 235,000 (within 500-year floodplains for all at-risk areas). Regional Population Affected: 696,000 (Stockton Metro Area, 2011 estimate). Total Population Potentially Affected: Approximately 25 million (includes Stockton Metro Area and Delta Export Service Area1
) and three million acres of farmland.
Historical events indicate that geotechnical failures within the study area are occurring and will occur in the future due to seepage.
Levee maintenance will be covered under existing O&M manuals and will be brought into compliance with those requirements using a System Wide Improvement Framework. The following ongoing Sponsor projects will be constructed prior to the period of analysis for this study:
RD 404 cutoff wall to address seepage issues in the levee in Boggs Tract; and RD 17 Phases 1-3 to remedy levee seepage (detailed in Section 5.23.3) FWOP conditions include the impacts of sea level rise due to climate change, which is expected to reduce the level of performance of some existing levees. Due to the uncertainty in changes of inland hydrology (peak runoff) due to climate change, the report includes a qualitative description of potential impacts.
Future development will occur in compliance with FEMA regulations, SB 5 and other local land-use planning rules and regulations.
EXISTING NON-STRUCTURAL FEATURES
There are several small flood risk management features that were constructed by private landowners or local or regional governments to reduce the consequences of flooding in the study area. These features include small berms, diversion structures and drainage canals. It is assumed that all of these features will remain in place under the FWOP condition.
1 “The Delta Service Area is defined as those areas of the state outside the Delta that receive water from the State Water Project or the Central Valley Project, either directly or by exchange, by means of diversions through the Sacramento San Joaquin Delta.
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CHAPTER 3 — PLAN FORMULATION
The formulation, evaluation and comparison of alternative plans comprise the third, fourth and fifth steps of the USACE planning process, referred to collectively as Plan Formulation. Plan Formulation is a structured and highly iterative process to develop and refine a reasonable range of alternative plans, then narrow down to a final array of feasible plans, from which a single plan may be recommended for authorization and implementation.
MEASURES
A measure addresses one or more planning objectives. Table 3-1 lists the preliminary management measures identified indicates the objectives to which they contribute. The measures were screened to determine whether each should be retained for use in the formulation of alternative plans (Table 3-2).
These measures primarily achieve FRM objectives in the study area. Some measures may also contribute to environmental quality objectives through sound environmental design of the project. FRM measures can be non-structural or structural. Non-structural measures reduce flood damages without altering the nature or extent of flooding and- are accomplished by changing the use of the floodplains or by adapting existing uses to the flood hazard. In contrast, structural measures alter the nature or extent of flooding by modifying the magnitude, duration, extent or timing of flooding.
When considering opportunities to apply FRM measures in the study area, an understanding of the basic magnitude of costs to construct the measures is useful when compared to the maximum potential FRM benefits possible. Reduction in flood damages translates into monetary benefits, which in turn help determine if the Federal government can participate in a project (i.e., the Federal interest).
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Table 3-1: Initial Screening of Management Measures
General Measures
Objectives
Reduce Flood
Risk
Reduce
Flood
Damages
Implement
Sustainable
Environmental
Design
Minimize
Residual
Risk
Flood Warning, Emergency
Evacuation Plan X X X
Floodplain Management X X X
Elevate Critical Infrastructure X X X
Ring Levees for Critical
Infrastructure X X
Elevate/Relocate/Buy Out
Structures X X X
Levee Raise X X
Cutoff Wall X X
Deep Soil Mixing (Seismic) X X X
Setback Levee X X X
Seepage/Stability Berm X X
Erosion Protection X
Bridge Modification for
Conveyance X X
Upstream Bypass X X
Channel Modification for
Conveyance X X X
Bypass Channels X X X
Control Structure X X
Levee Extension X X X
Closure Structure X X X
Improve Existing Levee X X X
Reservoir Reoperation X X
Additional Reservoir Storage X X
Additional Transitory Floodplain
Storage X X
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Table 3-2: Summary of Management Measures Retained or Dropped Measures Retained Dropped Reason for Elimination
Non-Structural Measures
Flood Warning, Emergency
Evacuation Plan X
Floodplain Management X
Elevate Critical
Infrastructure X Not cost effective.
Ring Levees for Critical
Infrastructure X Not cost effective. Critical infrastructure would be inaccessible during flood events.
Elevate/Relocate/Buy Out
Structures X Not cost effective.
Structural Measures
Levee Raise X
Cutoff Wall X
Deep Soil Mixing (Seismic) X
Setback Levee X
Seepage/Stability Berm X
Erosion Protection X
Bridge Modification for
Conveyance X
Upstream Bypass X Not cost effective. Does not adequately address flood risk where most needed.
Channel Modification for
Conveyance X
Bypass Channels X
Control Structure X
Levee Extension X
Closure Structure X
Improve Existing Levee X
Reservoir Reoperation X
Not cost effective. Reoperation or expansion of
reservoirs would require 1,000,000 acre-feet of
additional storage capacity to be effective.
Additional Reservoir
Storage X Outside the scope of the study.
Additional Transitory
Floodplain Storage X
Previous analysis shows this would result in
negligible changes in flood stages within the
study area.
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FORMULATION AND EVALUATION OF INITIAL ALTERNATIVE PLANS
3.2.1 FORMULATION STRATEGY
An initial array of FRM alternative plans was developed, evaluated and compared to identify a plan that reasonably maximizes the net benefits (benefits minus costs). The alternatives were formulated to address specific flooding sources using measures to reduce the consequences to the maximum extent possible. This initial array of FRM alternative plans primarily consists of various levee improvement configurations, developed on the assumption that the North and Central Stockton and RD 17 areas are hydraulically separable.
The retained measures generally need to be combined with other retained measures in order to develop complete alternative plans. Table 3-3 illustrates which measures were combined to form the various alternative plans. Descriptions and figures illustrating the initial alternatives are located in Appendix B:
Engineering. In the table, NS refers to North Stockton; CS refers to Central Stockton and RD17 refers to RD 17 for the geographic location of the alternative. MCB refers to Mormon Channel Bypass and PCB refers to Paradise Cut Bypass.
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Table 3-3: Inclusion of Measures in Initial Alternative Plans Measure
→
Alternative
↓
Flood Warning, Emergency Evacuation PlanFloodplain ManagementLevee RaiseCutoff WallDeep Soil Mixing (Seismic)Setback LeveeSeepage/Stability BermErosion ProtectionBridge Modification for ConveyanceChannel Modification for ConveyanceBypass ChannelsControl StructureLevee ExtensionClosure StructureImprove Existing Levee
NS-A X X X X X X X
NS-B X X X X X X X X
NS-C X X X X X X X
NS-D X X X X X
NS-E X X X X
NS-F X X X X X X X X
CS-A X X X X
CS-B X X X X X
CS-C X X X X
CS-D X X X X X X
CS-E X X X X
CS-F X X X X X X
CS-G X X X X X X
RD17-A X X X X
RD17-B X X X X X
RD17-C X X X X X
RD17-D X X X X X X X
RD17-E X X X X X X X X X
RD17-F X X X X
RD17-G X X X X X X X X X
PCB X X X X X X X
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INITIAL ALTERNATIVES ANALYSIS
Alternatives for each area were analyzed by using a modification of the Parametric Cost Estimation Tool (PCET) developed for the Sutter Basin Feasibility Study by URS, Inc. The PCET tool was proven as a reliable estimator for the costs of levee construction and repairs. Potential environmental mitigation costs for each reach were included in the estimates, as well as potential real estate acquisition costs for landside right-of-way or easement from the existing levee landside toe. This allowed use of inventory data for the areas, including population, number of structures and counts of critical infrastructure for comparisons.
Critical infrastructure is defined as public structures where any risk of flooding is too great, such as hospitals, nursing homes, jails, fire and police stations and schools. Residual floodplains were modeled to determine effect of the alternatives.
Using the information described above, USACE and the sponsors determined the annual and net benefits effectively representing economic performance of an alternative. Life safety or the ability of an alternative to reduce risk to population from residual flood damages was ranked on a scale ranging from poor to excellent. Alternatives were briefly analyzed relative to compliance with EO 11988. Floodplain Management and the North and Central Stockton areas were preliminarily determined to have met the intent of EO 11988 due to the built-out nature of the areas; RD 17 has planned development which makes it difficult to comply with the EO 11988 guidance; Mormon Channel meets goals of EO 11988 through the ER benefits that could be realized. See section 3.6 for the detailed EO 11988 analysis.
The team used existing information to evaluate the economic benefits of the Paradise Cut setback alternatives. A series of incremental improvements were evaluated and modeled by MBK Engineers for the River Islands development project (MBK, 2008). The observed decrease in efficiency as the project size increases is consistent with the hydraulic limitations presented by the downstream stage boundary being within the tidal region of the Delta.
To reduce to a reasonable range of alternatives to be carried forward into a focused array, only the two alternatives for each area that maximized net benefits were carried forward. For RD 17, only one alternative, RD17-E, was shown to have positive net benefits and provide reduced risk. Of the bypass alternatives, Mormon Channel has positive net benefits and was carried forward. The Paradise Cut Bypass alternative was not carried forward, as it is not cost effective and brings about concerns regarding downstream impacts of widening the bypass.
In compliance with USACE ER 11-1-321, a Value Engineering study was held July 22-26, 2013. USACE and the NFS used the initial alternatives in order to develop composite alternatives to be analyzed and identify a recommended plan.
Table 3-4 summarizes the alternatives carried forward into development of the focused array of alternatives.
The Critical Structures Benefiting from Reduced Flood Risk column denotes the number of critical structures (hospitals, police and fire stations, etc.) with reduced flood risk resulting from the alternative with a 90% assurance at a 1% ACE event.
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Table 3-4: Initial Alternatives Retained
Alternative
Annual
Benefits
($1,000s)
Net Benefits
($1,000s) Life Safety
Critical
Structures
Benefiting
from Reduced
Flood Risk
NS-B
Delta Front North and South
and Calaveras River
72,000 53,000 Very Good 0
NS-F
Delta Front North and South
and Full Calaveras River
76,000 54,000 Excellent to
Very Good 0
CS-D
Calaveras River, Diverting
Canal and San Joaquin
River
69,000 56,000 Excellent to
Very Good 0
CS-F
Calaveras River and San
Joaquin River
56,000 46,000 Good 5
CS-G
Mormon Channel Bypass 13,000 11,000 Fair 134
RD17-E
SJR North with Tieback and
Extension
27,000 12,000 Excellent to
Very Good 51
FOCUSED ARRAY OF ALTERNATIVES
The strategy to move the initial array of alternative plans forward included: (1) applying metrics to the initial array of alternatives; (2) selecting the best alternatives for each separable area or levee reach based on parametric cost and benefit analysis; (3) and combining the best alternatives into an alternative to be carried forward. Alternatives were formulated using ER 1100-2-8162, Incorporating Sea Level Changes in Civil Works Programs, curve two to account for sea-level change over the design life of the project. A sensitivity analysis was also conducted. Using the nomenclature and basic alternatives presented in the Alternatives Milestone meeting, USACE, SJAFCA and DWR developed a focused array of alternatives.
All of the alternatives except Alternative 10 include an extension of the RD 17 tie-back levee and were designed to pass a 0.5% ACE flood with 90% assurance. It was estimated that only a few short reaches of levee required height increases to pass a 0.5% ACE event with 90% assurance and incremental benefits would exceed the incremental cost. Therefore, alternatives attaining lower levels of performance were not formulated. Levels of performance greater than the 90% assurance of passing a 0.5% ACE flood were not developed due to a lack of sponsor interest in a more expensive plan. The performance of Alternative 10 was not able to obtain the same performance of the other alternatives because the existing RD 17 tie-back levee was found to be outflanked for floods larger than 1% ACE. The floodwaters that outflanked the tieback levee would result in higher stages (relative to the other alternatives) along the right bank of French Camp Slough.
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Table 3-5 summarizes the focused array of alternatives. Descriptions and figures showing the proposed alignments of the focused array of alternatives are on the following pages.
Table 3-5: Focused Array of Alternatives
Name Increments Description
Alternative-1 – No Action None No Action
Alternative-2A – Delta Front and
Mainstem Levees
NS-F, CS-D,
RD17-E
Levee Improvements, Closure
Structures, No Bypass, with Stockton
Diverting Canal
Alternative-2B – Delta Front and
Mainstem Levees
NS-B, CS-F,
RD17-E
Levee Improvements, Closure
Structures, No Bypass
Alternative-4 Delta Front and Mainstem
Levees and Mormon Channel Bypass
NS-B, CS-F,
RD17-E, CS-G
Levee Improvements, Closure
Structures, Mormon Channel Bypass
Alternative-7 – Delta Front, Lower
Calaveras River and San Joaquin River
Levee Improvements
Alternative 2B
+ Raise
Levee Improvements, Closure
Structures, No Bypass, Levee Raises
Alternative-8 – Delta Front, Lower
Calaveras River, San Joaquin River and
Stockton Diverting Canal Levee
Improvements
Alternative 2A
+ Raise
Levee Improvements, Closure
Structures, No Bypass, with Stockton
Diverting Canal, Levee Raises
Alternative-9 – Delta Front, Lower
Calaveras River, San Joaquin River
Levee Improvements and Mormon
Channel Bypass
Alternative 4 +
Raise
Levee Improvements, Closure
Structures, Mormon Channel Bypass,
Levee Raises
Alternative-10 – North and Central
Stockton – Delta Front, Lower Calaveras
River, San Joaquin River and Stockton
Diverting Canal Levee Improvements
Alternative 8
w/o RD 17 +
Raise
Levee Improvements, Closure
Structures, No Bypass, with Stockton
Diverting Canal, Levee Raises
Notes:
1. A now obsolete Alternative 3 was comprised of SB 5 levee raise measures that are included Alternatives 7, 8, 9, and 10.
2. Alternative 5, Urban Flood Risk Reduction/Cross Levees was not economically justified and was dropped from further analysis.
3. A non-structural Alternative 6 was eliminated as being un-implementable due to high cost of flood-proofing, relocating, or raising structures.
4. Some non-structural measures can be included in all alternatives (i.e., Flood Warning, Emergency Evacuation Plan (FWEEP), Floodplain Management).
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The resulting focused array of alternatives is described as follows:
Alternative 1 (No Action): This would include no Federal action. There are locally sponsored activities ongoing and potential for other local or State sponsored projects that could be undertaken without Federal participation. It is expected that current FRM structures would be maintained and residual risk of flood damages would remain.
Alternative 2A: This combines the following alternatives to arrive at a comprehensive solution: North Stockton Alternative F, Central Stockton Alternative D and RD 17 Alternative E (Figure 3-1). It would implement levee improvements without implementing Mormon Channel bypass. Levee improvements would be to the authorized design flow and the extent of levee repairs would be approximately 53.1 miles (280,600 feet).
Alternative 2B: This combines the following alternatives: North Stockton Alternative B, Central Stockton Alternative F and RD 17 Alternative E (Figure 3-2). It would implement levee improvements without implementing Mormon Channel bypass. Levee improvements would be to the authorized design flow and the extent of levee repairs would be approximately 42.5 miles (224,400 feet).
Alternative 4: This includes levee raises to meet SB 5 height requirements. The components of this plan are: North Stockton Alternative B, Central Stockton Alternative F, RD 17 Alternative E and the Mormon Channel Bypass (Figure 3-3). It would implement levee improvements along with restoration of the Mormon Channel, including a diversion control structure at the Stockton Diverting Canal. The estimated extent of levee repairs would be 42.5 miles (224,400 feet) plus 6.3 miles (33,400 feet) of channel work for the Mormon Channel portion.
Alternative 7: This combines North Stockton Alternative B, Central Stockton Alternative F and RD 17 Alternative E (Figure 3-4). It would implement levee improvements without implementing Mormon Channel bypass, combining the levee improvement measures of cutoff wall, deep soil mixing (seismic), seepage berm in RD 17 and levee geometry improvements. It would address projected Sea Level Change (SLC) by including raises in levee height where needed. There would also be 2.2 miles of new levee constructed to extend the RD 17 tie-back levee and the secondary levee at the Old River flow split. The new levees would include a cutoff wall to address potential seepage issues.
Alternative 8: This combines the following alternatives: North Stockton Alternative F, Central Stockton Alternative D and RD 17 Alternative E (Figure 3-5). It would implement levee improvements without implementing Mormon Channel bypass, combining the levee improvement measures of cutoff wall, deep soil mixing (seismic), seepage berm and levee geometry improvements. It would address projected SLC by including raises in levee height where needed. There would also be 2.2 miles of new levee constructed to extend the RD 17 tie-back levee and the secondary levee at the Old River flow split. The new levees would include a cutoff wall to address potential seepage issues.
Alternative 9: This combines the following alternatives: North Stockton Alternative B, Central Stockton Alternative F, RD 17 Alternative E and the Mormon Channel Bypass (Figure 3-6). It would implement levee improvements along with restoration of the Mormon Channel including a diversion control structure at the Stockton Diverting Canal. This alternative combines the levee improvement measures of cutoff wall, deep soil mixing (seismic), seepage berm and levee geometry improvements. It would address projected SLC by including raises in levee height where needed. There would also be 2.2 miles of new levee constructed to extend the RD 17 tie-back levee and the secondary levee at the Old River flow split. The new levees would include a cutoff wall to address potential seepage issues. The diversion control structure for Mormon Channel at the Stockton Diverting Canal would consist of pipe culverts with gates to control releases to a maximum flow of 1,200 cfs to Mormon Channel.
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Alternative 10 – North and Central Stockton: This combines the following alternatives: North Stockton Alternative F and Central Stockton Alternative D (Figure 3-7). It would implement levee improvements without implementing Mormon Channel bypass. This alternative combines the levee improvement measures of cutoff wall, deep soil mixing (seismic), seepage berm and levee geometry improvements. It would address projected SLC by raising levee height where needed. The proposed levee improvements are comparable to Alternative 8, with the exception of the RD 17 components, which are not included.
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Figure 3-1: Alternative 2a
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Figure 3-2: Alternative 2b
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Figure 3-3: Alternative 4
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Figure 3-4: Alternative 7
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Figure 3-5: Alternative 8
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Figure 3-6: Alternative 9
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Figure 3-7: Alternative 10
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COMPARISON OF FINAL ARRAY OF ALTERNATIVE PLANS AND DECISION
CRITERIA
In addition to refining the alternatives, modified versions of Alternative 7 and Alternative 9 were added to the final array for compliance with EO 11988. These modified alternatives did not include improvements in RD 17. The alternatives previously referred to as Alternatives 7 and 9 were reclassified as Alternatives 7b and 9b, respectively. The modified versions with RD 17 removed were classified as Alternatives 7a and 9a. For consistency in nomenclature, Alternative 8 was reclassified as Alternative 8b, and Alternative 10 (Alternative 8 without RD 17 improvements) was reclassified as Alternative 8a.
During further analysis of the focused array of alternatives, analysis for potential relative Sea Level Change (SLC), was conducted, in accordance with USACE ER 1100-2-8162, Incorporating Sea Level Changes in Civil Works Programs (31 December 2013). The alternatives were compared following the method described in Section 6.d (1). Curve two under the cited guidance was used in the future hydrology to account for estimated SLC. The alternatives include a subset that was scaled to provide a 0.5% level of performance without SLC (2A, 2B, 4) and a paired subset that was scaled to account for estimated SLC (7a, 8a, 9a, 7b, 8b, 9b). The alternatives were otherwise equivalent.
The alternatives that were scaled to provide 0.5% ACE, including future SLC, provided greater net benefits than alternatives scaled to provide a 0.5% level of performance under existing conditions. Alternatives 2A, 2B and 4 were removed from further consideration, based on this information. The last step of the method in Section 6.d (1) of ER 1100-2-8162 is to evaluate the performance of the selected alternative to other rates of SLC. This evaluation was conducted after selection of the Recommended Plan (RP).
Table 3-6 describes the final array of alternatives. Figures 3-8 through 3-13 display the features of each alternative.
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Table 3-6: Final Alternative Descriptions
Name Description
Alternative 1 – No Action No Action
Alternative 7a – North and Central Stockton – Delta Front, Lower Calaveras River and San Joaquin River Levee
Improvements excluding RD 17
Levee Improvements, Closure Structures,
No Bypass, Levee Raises, New Levee
Alternative 7b – North and Central Stockton – Delta Front, Lower Calaveras River and San Joaquin River Levee
Improvements including RD 17
Levee Improvements, Closure Structures,
No Bypass, Levee Raises, New and
Setback Levees
Alternative 8a – North and Central Stockton – Delta Front, Lower Calaveras River, San Joaquin River and Stockton
Diverting Canal Levee Improvements excluding RD 17
Levee Improvements, Closure Structures,
No Bypass, with Diverting Canal, Levee
Raises, New Levee
Alternative 8b – North and Central Stockton – Delta Front, Lower Calaveras River, San Joaquin River and Stockton
Diverting Canal Levee Improvements including RD 17
Levee Improvements, Closure Structures,
No Bypass, with Diverting Canal, Levee
Raises, New and Setback Levees
Alternative 9a – North and Central Stockton – Delta Front, Lower Calaveras River, San Joaquin River Levee
Improvements and Mormon Channel Bypass excluding RD
17 Levee Improvements, Closure Structures,
Mormon Channel Bypass, Levee Raises,
New Levee
Alternative 9b – North and Central Stockton – Delta Front, Lower Calaveras River, San Joaquin River Levee
Improvements and Mormon Channel Bypass including RD
17 Levee Improvements, Closure Structures,
Mormon Channel Bypass, Levee Raises,
New and Setback Levees
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Figure 3-8: Alternative 7a
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Figure 3-9: Alternative 7b
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Figure 3-10: Alternative 8a
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Figure 3-11: Alternative 8b
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Figure 3-12: Alternative 9a
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Figure 3-13: Alternative 9b
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Table 3-7 demonstrates the effectiveness of the alternatives in meeting the planning criteria defined by the Principles and Guidelines. The criteria are defined:
Completeness – “Completeness is the extent to which a given alternative plan provides and accounts for all necessary investments or other actions to ensure the realization of the planned effects. This may require relating the plan to other types of public or private plans if the other plans are crucial to realization of the contributions to the objective.”
Effectiveness – “Effectiveness is the extent to which an alternative plan alleviates the specified problems and achieves the specified opportunities.”
Efficiency – “Efficiency is the extent to which an alternative plan is the most cost-effective means of alleviating the specified problems and realizing the specified opportunities, consistent with protecting the Nation’s environment.”
Acceptability – “Acceptability is the workability and viability of the alternative plan with respect to acceptance by State and local entities and the public and compatibility with existing laws, regulations and public policies.”
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Table 3-7: Planning Criteria Analysis for Final Alternatives Final Alternatives Completeness Effectiveness Efficiency Acceptability Alternative 1 – No Action No No No No
Alternative 7a – North and
Central Stockton – Delta
Front, Lower Calaveras
River and San Joaquin River
Levee Improvements
excluding RD 17
Yes Yes Yes Yes
Alternative 7b – North and
Central Stockton – Delta
Front, Lower Calaveras
River and San Joaquin River
Levee Improvements
including RD 17
Yes Yes Yes No1
Alternative 8a – North and
Central Stockton – Delta
Front, Lower Calaveras
River, San Joaquin River
and Stockton Diverting
Canal Levee Improvements
excluding RD 17
Yes Yes Yes Yes
Alternative 8b – North and
Central Stockton – Delta
Front, Lower Calaveras
River, San Joaquin River
and Stockton Diverting
Canal Levee Improvements
including RD 17
Yes Yes Yes No1
Alternative 9a – North and
Central Stockton – Delta
Front, Lower Calaveras
River, San Joaquin River
Levee Improvements and
Mormon Channel Bypass
excluding RD 17
Yes Yes Yes Yes
Alternative 9b – North and
Central Stockton – Delta
Front, Lower Calaveras
River, San Joaquin River
Levee Improvements and
Mormon Channel Bypass
including RD 17
Yes Yes Yes No1
1 See Section.3.6
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EO 11988, FLOODPLAIN MANAGEMENT
EO 11988 ANALYSIS
ER 1165-2-26 provides the general guidance and policy for USACE’s implementation of EO 11988 for all civil works projects. Paragraph 7 of the regulations states: “…It is the policy of the Corps of Engineers to formulate projects which, to the extent possible, avoid or minimize adverse impacts associated with use of the base floodplain and avoid inducing development in the base floodplain unless there is no practicable alternative. The decision on whether a practicable alternative exists will be based on weighing the advantages and disadvantages of floodplain sites and non-floodplain sites. Factors to be taken into consideration include, but are not limited to…the functional need for locating the development in the floodplain…The test of practicability will apply to both the proposed Corps action and to any induced development likely to be caused by the action.”
Figure 3-14 outlines the analysis process as described in 43 FR 6030, U.S. Water Resources Council, Floodplain Management Guidelines for Implementing EO 11988, dated February 10, 1978.
Figure 3-14: Decision Making Process for EO 11988
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To comply with EO 11988 and ER 1165-2-26, projects are formulated and recommended that, to the extent possible, avoid, minimize and/or mitigate adverse effects associated with use of the floodplain and avoid inducing incompatible development unless there is no practicable alternative. Achieving flood and coastal storm risk management objectives generally cannot avoid locating actions in riverine or coastal floodplains.
The requirements below are consistent with the EO 11988 decision process displayed in Figure 1 in Water Resources Council, Floodplain Management Guidelines for Implementing EO 11988, February 10, 1978 (43 FR 6030) (Figure 3-14).
1. Determine if the proposed action is in the base floodplain.
The overall purpose of the project is to reduce flood risk to urban and urbanizing parts of the study area.
The final array of alternatives involve improving levees or constructing new levees located in the base 1% ACE floodplain. For the purpose of this study, the base floodplain is delineated as all areas that are at risk of being flooded by the 1% ACE flow; it has been delineated assuming existing levees do not provide protection from the 1% ACE event. This definition of the base floodplain addresses the USACE requirement in ER 1105-2-101 to describe a project’s performance using risk and uncertainty methods and for purposes of studies ER 1105-2-101, does not require USACE to give deference to the current accreditation for RD 17’s levee system provided by the FEMA in 2011. For this reason, the entire study area was evaluated for EO 11988 compliance.
2. If the action is in the base floodplain, identify and evaluate practicable measures to the action or to the location of the action in the base floodplain.
The study evaluated all practicable measures (40 FR 6030) by following the six-step planning process and evaluating a wide range of measures using available information, professional judgment and risk-informed decision making to achieve the project purpose. Practicable measures (structural and non-structural) considered are as follows:
North Stockton
No Action: This would involve no Federal action within the base floodplain. No additional reductions in flood risk would be realized.
Improvement of Paradise Cut: Screened out because the cost exceeded the benefits and it did not address geotechnical levee failure modes.
Flood proofing and raising existing structures and infrastructure: Determined to not be cost effective. Reservoir reoperation: Screened out due to potential system-wide effects and because it did not address geotechnical failure modes.
Reduce geotechnical failure probability and increase height of existing levees: These measures were retained. The geotechnical issues addressed are primarily through and under seepage with areas on the Delta Front requiring seismic stabilization.
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Central Stockton
No Action: This would involve no Federal action within the base floodplain. No additional reductions in flood risk would be realized.
Improvement of Paradise Cut: Screened out because the cost exceeded the benefits and it did not address geotechnical levee failure modes.
Flood proofing and raising existing structures and infrastructure: Determined to not be cost effective. Reservoir reoperation: Screened out due to potential system-wide effects and because it did not address geotechnical failure modes.
Reduce geotechnical failure probability and increase height of existing levees: These measures were retained. The geotechnical issues addressed are primarily through and under seepage with areas on the Delta Front requiring seismic stabilization.
RD 17
No Action: This would involve no Federal action within the base floodplain. No additional reductions in flood risk would be realized for 46,500 existing residents and two major highways, two major railroads and the Sharpe Army Depot.
Improvement of Paradise Cut: Screened out because the cost exceeded the benefits and it did not address geotechnical levee failure modes.
Flood proofing and raising existing structures and infrastructure: Determined to not be cost effective. Reservoir reoperation: Screened out due to potential system-wide effects and because it did not address geotechnical failure modes.
Ring levees: Inclusion may be effective in some study areas, but will need to be incrementally cost effective to be practicable.
Set-back levees: Determined to be cost effective for one reach in RD 17 with a length of approximately 3,500 feet.
Reduce geotechnical failure probability and increase height of existing levees: These measures were retained. The geotechnical issues addressed are primarily through and under seepage with areas on the Delta Front requiring seismic stabilization.
There are measures (40 FR 6030) that are outside USACE and the non-Federal sponsors’ authority to implement, but may be considered by the local authorities:
Institute a building moratorium within the study area; however, this does not address existing infrastructure.
Implement building code requirements to elevate new construction above the 1% flood elevation; however, this measure does not address existing infrastructure.
Non-structural measures were not cost effective given that previous land use decisions were made based on FEMA accredited levees (Shaded Zone X) in all study areas. Currently, there is a section of Central Stockton that is designated as Zone A. The 2 square mile area is bounded by the Calaveras River to the north and Smith Canal to the south. The rest of the study area currently remains Shaded Zone X.
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Detailed analyses were performed for the final array that found the structural improvements to be the only practicable and cost effective possibilities that achieve project objectives. Implementation of the proposed structural measures will reduce the flood risk to thousands of commercial, institutional and residential structures and transportation routes.
3. If the action must be in the floodplain, advise the general public in the affected area and obtain their views and comments.
Early public review has been conducted through public scoping via a published NOI to Prepare an EIS, a public scoping meeting, and public comments received on the Draft Report of the proposed study. Interested parties and resource agencies have been coordinated with during the course of the study. Additional opportunities for public input and comment will be provided during the review period for the Final Integrated Report.
4. Identify beneficial and adverse impacts due to the action and any expected losses of natural and beneficial floodplain values. Where actions proposed to be located outside the base floodplain will affect the base floodplain, impacts resulting from these actions should also be identified. a. Beneficial impacts due to the action.
The existing non-project and project levees along the Delta Front and Calaveras River provide FRM for approximately 131,000 people in the northern portion of the city of Stockton. The levees also provide FRM for critical infrastructure including schools, fire and police stations, a hospital and major transportation routes including Interstate 5 and Highway 99. Inclusion of Delta Front and Calaveras River Alternatives will provide improved FRM to this large population and the existing critical infrastructure.
The existing project levees along the San Joaquin River and Calaveras River provide FRM for approximately 128,000 people in the central portion of the city of Stockton. The levees also provide FRM for critical infrastructure including schools, fire and police stations, a hospital and major transportation routes including Interstate 5 and Highway 99. Inclusion of San Joaquin River and Calaveras River Alternatives will provide improved FRM to this large population and the existing critical infrastructure.
The existing RD 17 project levees provide FRM for approximately 46,500 people in portions of the cities of Stockton, Lathrop, Manteca and San Joaquin County. The project levees also provide FRM for critical infrastructure including schools, fire and police stations, the county jail, Sharpe Army Depot, a hospital and major transportation routes including Interstate 5 and Highway 120. Inclusion of RD 17 Alternatives will provide improved FRM to this large population and the existing critical infrastructure.
Currently, the levee safety program has defined the levee system that incorporates RD 17 as bounded on the north by Walker Slough, west by the San Joaquin River and south by the Stanislaus River. This includes RD 17, RD 2096, RD 2094, RD 2075 and RD 2064 (Figure 3-15). The alternatives that include RD 17 incorporate a tieback extension at the southern end of RD 17, thereby placing a limit on future growth to the south by not providing improvements below Manteca. Without the tie-back extension, levee improvements would have been necessary further upstream on the San Joaquin River and along the Stanislaus River to achieve the same flood risk reduction for the already urbanized portions of RD 17 and would have added about 16,000 acres of land that would be available for future development. These plans are currently under revision and it is likely that the acreage may be reduced. It is unlikely that such a project could be economically justified.
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Figure 3-15: San Joaquin River East Levee System
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b. Adverse impacts due to the action.
The final array of alternatives will facilitate further development in North and Central Stockton. Any future development, about 2,700 acres, will be infill of existing developed areas. The alternatives that include RD 17 would facilitate development of disturbed, but non-urbanized areas of Stockton, Lathrop, Manteca and unincorporated San Joaquin County. The Stockton, Manteca and Lathrop General Plans designated 5,300 acres for urbanization within RD 17. A majority of the acres would be new urbanization versus infill. In addition, 7,200 acres of disturbed but not yet urbanized land would be available for future development should local communities update their General Plans. These plans are currently under revision and it is likely that the acreage may be reduced. The City of Lathrop has recently eliminated 2,055 acres from its Sphere of Influence. Compliance with the Delta Plan will also reduce the potential for development. The RD 17 levee system is currently accredited by FEMA; therefore, the area currently has no Federal restriction associated with development. Implementation of proposed structural improvements will meet certain compliance requirements for SB 5. Additional improvements will likely be necessary by non-Federal agencies in order to fully comply with SB 5. The penalty for non-compliance is a moratorium on future development until the appropriate level of FRM is attained. Alternatives including RD 17 would facilitate development by providing a higher degree of FRM. Figure 3-17 shows the planned development areas within RD 17 and inundation depths for the base flood (1% (1/100) ACE event). The 1% ACE, sometimes referred to as a "100-year" event, is equivalent to a flood event with a 1% chance of occurring in any given year. Full development of the infill would result in a population increase of approximately 20,000 people.
The current emergency evacuation plan identifies seven evacuation routes from the North and Central Stockton which is deemed adequate for current population. Since buildout of the infill is anticipated to be gradual over the project life, no adverse effect to the evacuation plan is expected. The City of Stockton updates their emergency response plans as needed and would accommodate population growth as part of such update.
c. Expected losses of natural and beneficial floodplain values.
The natural floodplain has been greatly reduced within the study area by the manner in which the existing levee system was constructed in the early 20th Century. The system was constructed with the levees in close proximity to the active river channel to maximize development of arable land for agriculture, followed by urban growth of the Stockton, Lathrop and Manteca communities into unincorporated areas of San Joaquin County. The Flood Control Act of 1944 provided USACE authorization to further improve the levee system.
The Standard O&M Manual for the LSJR Levees, Lower San Joaquin River and Tributaries Project, California, describes the protection provided by the project as follows:
“The Lower San Joaquin and Tributaries Project will provide protection from all floods of record to about 120,000 acres of fertile agricultural lands; to a suburban area south of the city of Stockton and about four small communities; to other areas developed for residential and industrial purposes; to two transcontinental highways and other State and County highways from all floods of record. The project made possible the reclamation of areas that can be developed to a higher degree when protection against flood hazard is assured.”
The natural floodplain was separated from the river channels by the levee system so that the functionality and natural values are severely constrained. Due to the urbanization, there are few opportunities for restoration of the natural floodplain in the study area. As described in Paragraph 5 below, there are 3,250 acres of planned development with infrastructure improvements in place in the Lathrop portion of RD 17.
The natural floodplain is not reduced within the study area by the proposed action.
Current placement of the levees and activities related to the improvements to those levees reduce the beneficial values of water resources (natural moderation of floods, water quality maintenance and ground water recharge); living resource values (fish, wildlife and plant resources) and cultural resource values ATTACHMENT D 1072
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(open space, natural beauty, scientific study, outdoor education and recreation). There are some benefits to cultivated resource values (agriculture, aquaculture and forestry) as a result of implementation of proposed improvements.
A large setback levee was evaluated for a reach of the main stem San Joaquin River adjacent to RD 17, but was not found to be economically justified. This alternative was not evaluated for ecosystem benefits as the study focused on single-purpose FRM plan formulation. Further, degradation of the existing levee may have adverse effects on the flow splits at Paradise Cut and Old River. The alternative was formulated to retain the existing FRM benefits to the area within the setback while retaining the existing flow splits at Old and Middle Rivers.
5. If the action is likely to induce development in the base floodplain, determine if a practicable nonfloodplain alternative for the development exists.
The areas of North and Central Stockton that would see improved FRM from the proposed alternatives are predominantly already developed. As shown in Figure 3-17, most potential future development within the floodplain would be infill of previously developed areas. This in-fill development is relatively modest in size and within the current city limits. The current General Plan for the City of Stockton accounts for this potential infill development in its coverage of emergency services and floodplain management plan.
In RD 17, agriculture was followed by the urban growth of the Stockton, Lathrop and Manteca communities into unincorporated areas of San Joaquin County. Due to the urbanization, there is a sizable population within the RD 17 basin. While the city limits of Stockton and Manteca have areas not yet urbanized that are outside the floodplain, the city of Lathrop is entirely within the 200-year floodplain. Due to this, there are no practicable alternatives to development within the floodplain. Within the city of Lathrop, 3,200 acres of infrastructure (utilities, roads, etc.) were placed in anticipation of additional development. The following describes major investments that have already occurred that would make it difficult to relocate some of the planned development.
West Lathrop Specific Plan Area: This includes vacant areas in the Mossdale Village portion of the West Lathrop Specific Plan Area and includes 230 acres of undeveloped land owned by Silviera, plus 131 acres under various ownerships. Full infrastructure was constructed to bring the transportation network and utilities (water, sewer, storm drainage, and flood control) to these properties and most properties pay special tax assessments for these improvements. Most of Mossdale has been constructed, and the over-sizing of these improvements anticipates and requires, that the remaining area within Mossdale be developed to pay back these costs. Tens of millions were spent on this infrastructure.
Central Lathrop Specific Plan (CLSP) Area: This includes 1520 master planned acres that were annexed.
Improvements include sewer and storm drain collection systems. $200 million in assessments were approved and $50 million were sold; another $50 million in developer equity to construct infrastructure.
Gateway Specific Plan Area: This includes 384 acres of industrial and commercially zoned property in an approved Specific Plan and EIR. Many acres were annexed and are under active development planning.
Millions were and tens of millions are about to be spent on infrastructure.
East (historic) Lathrop: This includes two underdeveloped areas, including 168 acres on McKinley near Shideler Parkway and 253 acres in the Louise/Park Avenue area. This was a portion of the original city of Lathrop boundaries and has full utilities and arterial roadways adjacent. It is under active development planning. Tens of millions were spent on infrastructure.
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Roth Road Area: This area of 250 acres is adjacent to the northern border of Lathrop and fronts a major arterial with existing water mains for build-out, paid for by assessments on the undeveloped parcels. All utilities have been master planned and detailed plans for storm drainage and sewer service are under review to allow for build-out. Millions were spent on infrastructure and tens of millions are about to be spent to allow development.
South Lathrop Specific Plan Area: This 315 acre industrial and commercial area within the 1989 General Plan boundaries has a Specific Plan, Development Agreement and EIR coming to the City Council for approval in the near future. Millions were spent on these entitlements.
The Oakwood Shores development, located within the deepest area of flooding in Manteca, has roads and utilities and many of the lots already contain houses. As Figure 3-17 shows, the proposed urbanization within RD 17 occurs in the deepest areas of inundation. While some of the planned development could be relocated from the deepest areas of inundation, it may not be practicable to fully relocate all future development outside the floodplain.
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Figure 3-16: Existing Land Use in Study Area
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Figure 3-17: Planned Development RD 17 and 1% ACE Inundation Area ATTACHMENT D 1076
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6. As part of the planning process under the Principles and Guidelines, determine viable methods to minimize any adverse impact of the action including any likely induced development for which there is no practicable alternative and methods to restore and preserve the natural and beneficial floodplain values. This should include reevaluation of the "no action" alternative.
The historic placement of levees in the study area precludes opportunities for restoration or enhancement of natural floodplain values. Setback levees were analyzed for RD 17 but were not economically justified.
For North Stockton, placement of the Delta Front levee along Fourteenmile Slough will allow some opportunity for restoration efforts.
Based on existing land use planning for further development in RD 17 in the deepest parts of the floodplain (highest life safety consequence), the decision was made to remove the RD 17 alternatives from further consideration (Alternatives 7b, 8b and 9b). The Principles and Guidelines state that Federal investments in water resources should avoid the unwise use of floodplains and flood-prone areas and minimize adverse impacts and vulnerabilities in any case in which a floodplain or flood-prone area must be used. While few practicable alternatives to development in the floodplain were identified, it was determined that the proposed development, as shown in the General Plans, is unwise from the perspective of supporting Federal investment for a FRM project under current land use plans.
7. If the final determination is made that no practicable alternative exists to locating the action in the floodplain, advise the general public in the affected area of the findings.
The public had an opportunity to comment on this analysis and determination when the Draft FR/EIS/EIR was released for concurrent public, resource agency, independent external peer and USACE technical, policy and legal reviews.
8. Recommend the plan most responsive to planning objectives established by the study and consistent with the requirements of the EO.
Existing infrastructure, such as transportation routes, housing, agricultural improvements, levees and drains, limits the potential for restoration of the San Joaquin River natural hydrology and ecosystem functions.
The RD 17 alternatives are removed from consideration based on the Principles and Guidelines, which state that Federal investments in water resources should avoid the unwise use of floodplains and flood-prone areas and minimize adverse impacts and vulnerabilities in any case in which a floodplain or flood-prone area must be used. The proposed placement of development within the RD 17 basin is in the deepest part of the floodplain (highest life safety consequence). The remaining alternatives (Alternatives 7a, 8a and 9a) have little or no unmitigated adverse effects due to the fully developed nature of the North and Central Stockton areas.
Critical Actions. Repeat steps 1 through 8 above for critical actions in the floodplain for the full range of potential residual flood risks. The critical action floodplain is defined as the 500-year floodplain (0.2 percent chance floodplain).
1. Determine if the proposed action is in the critical action floodplain.
Proposed actions being analyzed by this study are within the critical action floodplain.
2. If the action is in the critical action floodplain, identify and evaluate practicable alternatives to the action or to the location of the action in the base floodplain.
There are no practicable alternatives to the proposed actions being situated within the critical action floodplain. See Base Floodplain Step 2.
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3. If the action must be in the critical action floodplain, advise the general public in the affected area and obtain their views and comments.
See Base Floodplain Step 3.
4. Identify beneficial and adverse impacts due to the action and any expected losses of natural and beneficial floodplain values. Where actions proposed to be located outside the 0.2% floodplain will affect the 0.2% floodplain, impacts resulting from these actions should also be identified.
The critical infrastructure currently located in the critical action floodplain includes 2 major interstate and international highways (I-5, CSR-99), 4 hospitals, 9 fire stations, 8 police stations, 3 railroads, a wastewater treatment plant and an airport and currently consists of the developed portions of the Cities of Stockton, Lathrop and Manteca. There are no liquefied natural gas terminals and facilities producing and/or storing highly volatile, toxic or water-reactive materials in the study area. Current population at risk is approximately 235,000 within the 0.2% ACE natural floodplain and possible damageable property amounts to $28.7 billion. If flooded, an added dimension to the disaster would be a possible wastewater treatment plant containment failure, which would impact water quality in the Delta and could interrupt water deliveries to communities in the southern valley and to Southern California.
Beneficial impacts due to the action would include risk management to the current critical infrastructure within the study area. Adverse impacts include the possibility for additional critical infrastructure being located within the RD 17 basin, potentially in the deepest areas of flooding, thereby increasing the amount of the critical infrastructure already in place.
See Base Floodplain Step 4 above for the expected losses of natural and beneficial floodplain values discussion.
5. If the action is likely to induce development in the critical action floodplain, determine if a practicable non-floodplain alternative for the development exists.
There may be opportunities to locate future critical facilities outside the critical action floodplain. However, facilities such as schools and fire stations must be within close proximity to any future development.
Therefore, if development occurs as shown in Figure 3-17, there will be no practicable alternative for these critical facilities.
6. As part of the planning process under the Principles and Guidelines, determine viable methods to minimize any adverse impact of the action including any likely induced development for which there is no practicable alternative and methods to restore and preserve the natural and beneficial floodplain values. This should include reevaluation of the "no action" alternative.
See Base Floodplain Step 6.
7. If the final determination is made that no practicable alternative exists to locating the action in the floodplain, advise the general public in the affected area of the findings.
See Base Floodplain Step 7.
8. Recommend the plan most responsive to the planning objectives established by the study and consistent with the requirements of the EO.
As a result of the analysis required for compliance with EO 11988, USACE determined that alternatives 7a, 8a and 9a have little or no unmitigated adverse effects to floodplain areas and are therefore compliant with EO 11988.
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RESULT OF EO 11988 ANALYSIS
As a result of the analysis required for compliance with EO 11988, RD 17 alternatives 7b, 8b and 9b were removed from further consideration. It is understood that RD 17, with funding assistance from the State, is pursuing a phased strategy of levee improvements to increase the resistance of RD 17’s levee system to under and through seepage to address residual flood risk. Upon completion of that work, RD 17 intends to request USACE participation in additional improvements to achieve 0.5 percent ACE FRM in order to meet SB 5 requirements. Consideration of future Federal participation would be subject to demonstration of a Federal interest in such improvements.
ENVIRONMENTAL CONSIDERATIONS AND MITIGATION
NEPA and CEQA require that the environmental effects of a project be analyzed. Chapter 5 describes the environmental impacts of the study alternatives, and of measures that would mitigate impacts. Most impacts could be mitigated to less than significant, but certain resources would experience significant unavoidable impacts, even with mitigation.
REGIONAL CONTEXT
Riparian habitats are substantially reduced from their historical extents throughout the Central Valley. Only about 2 to 5 percent of the historic riparian habitat still exists (RHJV 2004). Establishment of the FRM system, with levees set immediately adjacent to the main rivers and tributaries, contributed to this decline and continues to result in conflicts between ecosystem health and sustainability and maintenance of the FRM system. Upstream of the proposed project area, considerable Federal and State investment was made to improve the riparian corridor as part of the San Joaquin River Restoration Program and the Federal and State refuge systems.
Riparian vegetation provides important ecological functions, including: wildlife habitat; migratory corridors for wildlife; pollution filtration and waterway shading, thereby improving water quality; provides connectivity between waterways and nearby uplands; and biomass (nutrients, insects, large woody debris, etc.) to adjacent waterways. Riparian forests and woodlands – even remnant patches – are important to resident and migratory fish, birds and other wildlife.
STUDY AREA
Throughout most of the study area, vegetation is highly altered and fragmented. Nevertheless, this vegetation is all that remains as habitat to resident and migratory fish and wildlife in the area. Oak woodland, riparian forest, riparian scrub-shrub, wetlands, annual grassland and Shaded Riverine Aquatic (SRA) habitat are present within the footprint of all of the alternatives.
IMPACT ANALYSIS AND COMPENSATORY MITIGATION
Each action alternative evaluated (Alternatives 7a, 7b, 8a, 8b, 9a and 9b) would remove nearly all existing waterside SRA and woody riparian vegetation in the reaches where levee improvements are proposed.
Opportunities to provide compensatory mitigation onsite are severely limited because of the proximity of the existing levees to the rivers and tributaries and by the feasibility phase assumption that the project will include the Vegetation Free Zone (VFZ) required by USACE ETL 1110-2-583. If the project is authorized and funded, the suitability of all or a portion of the project for a variance to the VFZ requirement would be evaluated during PED. This assumption also influences the magnitude of the impact on vegetation.
Compensatory mitigation would be accomplished through a combination of mitigation bank credits and offsite mitigation plantings. Mitigation costs are appropriately recognized within the parametric cost ATTACHMENT D 1079
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estimate. Table 3-8 summarizes waterside SRA and woody riparian vegetation that would be removed as a result of implementing each action alternative. Landside vegetation would be similarly affected.
Table 3-8: LSJRFS Waterside Vegetation1 Directly Impacted by Implementation of Each Action Alternative
Alternative
7a 8a 9a
NORTH STOCKTON
SRA (linear feet) 9,054 9,054 9,054
Woody Riparian (acres) 7 7 7
CENTRAL STOCKTON
SRA (linear feet) 25,508 25,674 25,508
Woody Riparian (acres) 27 27 27
RD 17
SRA (linear feet) 0 0 0
Woody Riparian (acres) 0 0 0
TOTAL
SRA (linear feet) 34,562 34,728 34,562
Woody Riparian (acres) 34 34 34 1
“Waterside” refers to the side of the levee nearest the proximate body of water (e.g. not the distant Delta). “Waterside Vegetation” refers to vegetation on the waterside levee slope and within 15 feet of the waterside levee toe.
IDENTIFICATION OF THE NED PLAN
The following paragraphs and tables show the analysis of the policy compliant plans to identify the NED plan.
Table 3-9 displays the economic summary analysis of the costs and benefits for the comparison of alternatives. Of note in the analysis is that the preliminary net benefits for the alternatives ranged from $283 to $294 million, within the error bounds of the analysis. The residual equivalent annual damages (EAD) a represent the damageable property remaining for all events for each alternative.
Table 3-9: Economic Summary for Final Alternatives
Alternative
Investment
Cost
($1,000s)1
Residual
EAD
($1,000s)
Annual
Benefits
($1,000s)2
Annual
Cost
($1,000s)
Net
Benefits
($1,000s)2 BCR
No Action –
Alternative 1 --- 362,000 -- -- -- --
Alternative
7a 1,005,000 65,000 322,000 39,000 283,000 8.26
Alternative
8a 1,143,000 48,000 340,000 46,000 294,000 7.39
Alternative
9a 1,015,000 57,000 330,000 41,000 289,000 8.05
1 Includes interest during construction.
2 Includes benefits during construction.
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Residual annual damages are the remaining annualized damages in the study’s economic impact areas after completion of the alternative. Because RD 17 was excluded from the final alternatives, there is no reduction of damages for that area. The alternatives reduce EAD within the study area by approximately 85% from the FWOP condition. Table 3-10 summarizes the information.
Table 3-10: Residual Damages
Alternative
Residual Annual Damages ($1,000s) EAD
Reduction
($1,000s)
% EAD
Reduction
in Study
Area
North
Stockton
Central
Stockton RD 17 Total
No Action –
Alternative 1 244,000 92,000 26,000 362,000 0 -
Alternative 7a 12,000 25,000 26,000 63,000 299,000 82.6% Alternative 8a 2,000 20,000 26,000 48,000 314,000 86.7% Alternative 9a 8,000 23,000 26,000 57,000 305,000 84.3% The results of comparing the plans in Table 3-9 showed that the net benefits of the alternatives are statistically equal given the methodology used in the analysis. Figures 3-18 and 3-19 show a more detailed breakdown of where the reduction in EAD may be realized for North and Central Stockton, respectively.
Alternative 7a had the highest net benefit of the final alternatives, being approximately $283 million with a BCR of 8.26 to 1. In accordance with ER 1105-2-100 Appendix G, Amendment #1 Exhibit G-1, “Where two cost effective plans produce no significantly different levels of net benefits, the less costly plan is to be the NED plan, even though the level of outputs may be less.” As such, Alternative 7a is identified as the NED Plan.
The identification of Alternative 7a as the NED Plan serves to set the level of Federal participation in the project. Alternative 7a may not fully meet the NFS objective of SB 5 compliance, but in order to expedite authorization, the NFS elected not to pursue a Locally Preferred Plan (LPP) at this time.
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Figure 3-18: North Stockton Residual Risk
Figure 3-19: Central Stockton Residual Risk
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SELECTING A RECOMMENDED PLAN
The system of accounts established by the Principles and Guidelines were used to evaluate the final array of alternatives. In Table 3-11, 1 represents minimum increase, 2 represents moderate increase and 3 represents large increase. The ratings represent the comparison of the alternatives to each other, not to the No Action alternative. The NED and life safety metrics are comparable to each other among Alternative 7a, Alternative 8a and Alternative 9a. An evaluation of flood-depth, human mobility and flood wave travel time did not indicate a high life safety risk differential between the action alternatives.
All the alternatives reasonably maximize net benefits. The RED account registers changes in the distribution of regional economic activity that result from each alternative plan. Evaluations of regional effects have used nationally consistent projections of income, employment, output and population. The EQ metric used was potential effect on the environment. The OSE metrics were population remaining at risk and available evacuation routes for the alternatives. The higher OSE rating for 8a results from reduction of residual floodplains for North and Central Stockton, improving safety and access to evacuation routes. While these ratings are subjective, it is evident that Alternative 8a reasonably maximizes project outputs across all four accounts.
Table 3-11: Comparison of Alternatives to Principles and Guidelines System of Accounts Alternative NED RED EQ OSE
No Action –
Alternative 1 1 1 1 1
Alternative 7a 3 3 1 2
Alternative 8a 3 3 1 3
Alternative 9a 3 3 1 2
Note: 1 represents minimum increase, 2 represents moderate increase and 3 represents large increase.
Table 3-12 summarizes information for the alternatives to demonstrate economic benefits and life-safety parameters that show differences between the alternatives. Project performance is represented by Annual Exceedance Probability (AEP) represented as a percentage. For example, a 1 percent AEP is equivalent to the area being flooded once every 100 years on average. The AEPs for the separable areas differ by alternative due to the amount the alternative reduces the probability of flooding. The AEPs range from 0.2 percent to 2.6 percent. For the population remaining at risk, the 1 percent AEP event is used to analyze evacuation routes and residual floodplains metrics.
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Table 3-12: Comparison of Alternatives
Analysis Metric Area No Action Alt 7a Alt 8a Alt 9a
Project performance by
Impact Area (AEP)1
North
Stockton 21% 1% 0.2% 0.5%
Central
Stockton 16% 1.7% 0.8% 1.5%
RD 17 2.6% 2.6% 2.6% 2.6%
Developable Area (acres) 15,541 15,541 15,541 15,541
Population with <90%
assurance for the 1% ACE
event
North
Stockton 83,000 83,000 0 83,000
Central
Stockton 79,000 79,000 0 79,000
RD 17 43,600 43,600 43,600 43,600
Critical Infrastructure
with <90% assurance for
the 1% ACE event2,4
23 23 11 23
Critical Infrastructure of
Regional Economic
Significance with <90%
assurance for the 1% ACE
event3,4
463 452 171 404
Evacuation Routes with
>90% assurance for the
1% ACE event
North
Stockton
(11)
0 9 11 9
Central
Stockton
(32)
0 25 32 25
RD 17 (7) 0 0 0 0 1 AEP – Annual Exceedance Probability as expressed in percentage. 2 Critical Infrastructure – Life Safety: Fire/Fire EMS, Police, Hospitals, Jails, Airports, WTP, WWTP. 3 Critical Infrastructure – Regional Economic Significance: Substations, Schools, Power Plants, Chemical Industry, Colleges, Intermodal Shipping, Heliports, Petroleum Bulk Plants, Broadcast Communication.
4 Structural inventory based on the 500-year floodplain: changes in affected floodplains seen at the 1% ACE event.
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Based on the information presented in Sections 3.6, 3.8 and 3.9 above, Alternative 7a is identified as the NED plan and selected as the RP.
THE RECOMMENDED PLAN
The RP is Alternative 7a, North and Central Stockton – Delta Front, Lower Calaveras River and San Joaquin River Levee Improvements excluding RD 17 (Figure 3-8). This plan meets the study objectives of reducing flood risk and flood damages, reducing flood risk to public health, safety and life, minimizes residual flood risks to the extent justified, and incorporates environmentally sustainable design principles.
Alternative 7a is the Preferred Alternative and the Environmentally Preferable Alternative under NEPA. It is also the Least Environmentally Damaging Practicable Alternative under the Clean Water Act (CWA).
The structural features of Alternative 7a include 23 miles of levee improvements and two closure structures, one at Fourteenmile Slough and the other at Smith Canal. The levee improvements include a cutoff wall, deep soil mixing (seismic), a new levee, levee geometry improvements and erosion protection.
Recommendations for addressing residual risk to be performed by the non-Federal sponsor include nonstructural features, such as Comprehensive Flood Warning Emergency Evacuation Planning and Floodplain Management. Specifics of such plans will be included in the language of the Project Partnership Agreement signed after project authorization.
Chapter 8 contains a description of the RP, and Section 8.1.5 shows tables with a first cost breakout for the RP as well as estimated annual costs. These costs may change during additional analysis.
Alternative 7a, if authorized, would be subject to cost sharing for FRM projects at a 65 percent Federal and 35 percent non-Federal ratio. The NFS are responsible for all LERRDs costs, a minimum of 5 percent cash and any additional cash needed to reach a minimum of 35 percent of the total project cost. The maximum non-Federal share is 50 percent of the total project cost. Table 8-7 shows the preliminary cost allocation for Alternative 7a.
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San Joaquin County, CA Description of Final Alternatives CHAPTER 4 — DESCRIPTION OF FINAL ALTERNATIVES
INTRODUCTION
This chapter provides additional details to the final array of alternatives identified in Chapter 3. NEPA requires a greater level of detail in order to analyze potential effects of the proposed alternatives on the natural and human environment. Under NEPA, both the proposed project and project alternatives are each analyzed at the same level. CEQA project alternatives are usually analyzed at a lesser degree than the proposed project and the primary comparison is as an alternative to the proposed project. The common objective of both CEQA and NEPA is to identify the potential impacts on the human environment if the preferred alternative is approved and consider alternatives that could also address the purpose and objectives of the project.
NEPA and CEQA take a slightly different approach to considering project alternatives. However, both sets of environmental laws have the objective to inform decision makers and the public of the environmental effects of a project and ways those effects could be mitigated through measures to avoid, minimize, rectify, reduce or compensate for adverse impacts.
DETERMINATIONS SINCE THE DRAFT REPORT WAS PUBLISHED
Since the Draft Report was released in February 2015, Alternative 7a has been identified as the:
Recommended Plan (RP)
NEPA Preferred Alternative
NEPA Environmentally Preferable Alternative
Clean Water Act Least Environmentally Damaging Practicable Alternative
CHANGES SINCE THE DRAFT REPORT WAS PUBLISHED
Since the Draft Report release in February 2015, some measures were refined and additional information incorporated. Alternative 7a, the RP, was refined to reduce or adjust the proposed footprint. The study approach to vegetation was clarified and an initial engineering review was completed to consider the likely suitability of levees for a variance to the vegetation USACE ETL 1110-2-583. Additional information and analysis was completed for the potential impacts of the RP on Federally listed species, designated critical habitat and essential fish habitat. In addition, refinements and clarifications were incorporated to address public and agency comments. In some cases, information was reorganized or consolidated to increase clarity and readability. These changes were made to augment, clarify or otherwise improve the information presented in the EIR. These changes do not result in significant new information, as defined by the CEQA Guidelines Section 15088.5 and as such do not result in requiring recirculation of the EIR prior to certification.
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San Joaquin County, CA Description of Final Alternatives
ALTERNATIVES CONSIDERED IN DETAIL
The Feasibility Study screened the alternative plans down to the final array of alternatives (with options).
The difference between the two options for the action alternatives is that option “a” excludes levee work in RD 17, while option “b” includes it. As noted in Chapter 3, the “b” plans were eliminated from consideration due to non-compliance with EO 11988. For the purposes of NEPA and CEQA, those alternatives were retained and are included in this analysis. Alternative 1, No Action
Alternative 7a, North and Central Stockton, Delta Front and Lower Calaveras River and San Joaquin River Levee Improvements (Chapter 3, Figure 3-8)
Alternative 7b, North and Central Stockton, Delta Front, Lower Calaveras River, San Joaquin River Levee Improvements and RD 17 Levee Improvements (Chapter 3, Figure 3-9) Alternative 8a, North and Central Stockton, Delta Front, Lower Calaveras River, San Joaquin River and Stockton Diverting Canal Levee Improvements (Chapter 3, Figure 3-10) Alternative 8b, North and Central Stockton, Delta Front, Lower Calaveras River, San Joaquin River and Stockton Diverting Canal Levee Improvements and RD 17 Levee Improvements (Chapter 3, Figure 3-11)
Alternative 9a, North and Central Stockton, Delta Front, Lower Calaveras River, San Joaquin River Levee Improvements and Mormon Channel Bypass (Chapter 3, Figure 3-12) Alternative 9b, North and Central Stockton, Delta Front, Lower Calaveras River, San Joaquin River Levee Improvements and Mormon Channel Bypass and RD 17 Levee Improvements (Chapter 3, Figure 3-13)
FINAL PROPOSED STRUCTURAL MEASURES
Alternatives are composed of different structural and non-structural measures or building blocks. Some structural measures are included in all alternatives but may vary in amount and/or location. Other structural measures are included in only some alternatives. Table 4-1 shows how the structural measures are applied to each of the action alternatives.
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San Joaquin County, CA Description of Final Alternatives Table 4-1: Structural Measures Included in Each Action Alternative Alternatives
Structural Measure1 7a 7b 8a 8b 9a 9b
Cutoff walls (mi) 20.1 34.2 30.6 44.7 20.1 34.2
Levee Reshaping (mi) 6 21 7 21.7 6 21
Seepage Berm (mi) 0 3.8 0 3.8 0 3.8
Floodwall (mi) 0.2 0.2 0.2 0.2 0.2 0.2
New Levee (mi) 0.75 2.2 0.75 2.2 0.75 2.2
Erosion Protection (most is landside) (mi) 5 9.7 5 9.7 5 9.7 Seismic Remediation (mi) 1.1 1.1 1.1 1.1 1.1 1.1
Setback levee (mi) 1.33 1.33 1.33 1.33 1.33 1.33
Closure Structure- Smith Canal (#) 1 1 1 1 1 1
Closure Structure Fourteenmile Slough (#) 1 1 1 1 1 1
Control Structure (Stockton Diverting Canal at
Old Mormon Slough) (#) 0 0 0 0 1 1
Channel Improvements (Mormon Channel
flood bypass) (mi) 0 0 0 0 6.3 6.3
New Bridges (#) 0 0 0 0 3 3
1 Note that all alternatives include jet grouting for some utility and difficult infrastructure crossings.
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San Joaquin County, CA Description of Final Alternatives
CUTOFF WALLS
The predominant measure to improve levee performance is a slurry cutoff wall for the length of the project, except for portions of the levees requiring a seismic fix in North Stockton. See Figure 4-1 for a typical cutoff wall plan.
Description
Seepage cutoff walls are vertical walls of low hydraulic conductivity material constructed through the embankment and foundation to cut off potential through and under seepage. In order to be effective in reducing under-seepage, cutoff walls usually tie into an impervious sub-layer and would be constructed through the levee crown. Cutoff wall depths range from approximately 20 to 70 feet.
Construction Methods
A cutoff wall would be installed by one of two methods: (1) conventional open trench cutoff wall or (2) Deep Soil Mixing (DSM) cutoff wall. The method selected for each reach would depend on the depth of the cutoff wall needed to address the seepage. The open trench method can be used to install a cutoff wall to a depth of 80 feet. The DSM method would be utilized for cutoff walls of greater depth.
Preparation
Prior to cutoff wall construction, the site and any staging areas would be cleared, grubbed and stripped. The levee is typically degraded by one-half its height to provide a sufficient working surface (approximately 30 feet) and reduce the risk of hydraulically fracturing the levee embankment from the insertion of slurry fluids.
Construction
Conventional Method. The conventional slurry method for cutoff walls is an open trench that uses an excavator with a long-stick boom to dig the slurry trench. The cutoff walls for the project would be a minimum of 3-feet in width and constructed from a working surface elevation to a design depth at least 3- feet into an impermeable layer. The conventional method has a maximum depth of 70 to 80 feet.
During construction, bentonite-water slurry is used to keep the trench open and stable prior to backfilling with the permanent wall material. Soil is mixed with bentonite to form soil-bentonite and then pushed into the trench, displacing the bentonite-water slurry. After a predetermined settlement period, an impervious cap is constructed above the cutoff wall and the levee is reconstructed using suitable material (Type 1 levee fill) to the correct design elevation and current USACE levee design criteria.
DSM Method. Cutoff walls in North and Central Stockton could extend deeper than 70 feet below the surface elevation. The DSM method would require large quantities of cement bentonite grout, necessitating the use of a contractor-provided, onsite batch plant and deliveries of concrete aggregate, concrete sand, bentonite and cement. The batch plant would be powered by generators or electricity from power lines and would be located within the project area or an adjacent staging area. The batch plant area would consist of an aggregate storage system, aggregate rescreen system (if needed), rewashing facility (if needed), the batching system, cement storage, ice manufacturing and the grout mixing and loading system. All aggregate used would be obtained from local, commercial offsite sources.
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San Joaquin County, CA Description of Final Alternatives From the batch plant, the grout mixture would be transported through high-pressure hoses (8,000 pounds per square inch [psi]) to the location of construction. A crane supported set of 2 to 4 mixing augers would be used to drill through the levee crown and subsurface to a maximum depth of 140 feet. As augers are inserted and withdrawn, cement bentonite grout would be injected through the augers and mixed with native soils. An overlapping series of mixed columns would be drilled to create a continuous seepage cutoff barrier. Once the slurry hardened, it would be capped and the levee embankment reconstructed with impervious or semi-impervious soil.
Excavated and Borrow Material Staging. Excavated and borrow material would be stockpiled at staging areas. Haul trucks, front end loaders and scrapers would bring materials to the site to be spread evenly and compacted according to levee design plans. The levee would be hydro-seeded once construction was completed.
Equipment
Equipment used in construction includes a water/bentonite slurry mixing facility, a backhoe or long reach trench excavator, a bulldozer for moving soil and mixing slurry material and a water line to produce the slurry product. The water/bentonite slurry is mixed onsite with soil as the final product used during the trench excavation.
Risk Management
Trench Management. For conventional cutoff walls (up to 80 feet below working surface), the integrity of the open trench is maintained through specifications for density of the trench bentonite slurry mixture.
There are quality assurance/quality control testing requirements throughout construction that monitor mixture density to assure an open trench is maintained; walls exceeding 80 feet in depth would not involve an open trench.
Containment of Trench Slurry - Possibility of Fracture. To address containment of a trench slurry, the possibility of a fracture is reduced by degrading the levee to half of its original height to achieve a larger prism; this creates a wider working surface and placement of barriers to capture any surface materials. If a fracture were to occur, work would immediately stop and Federal, local and environmental agencies would be contacted to determine the extent and degree of remediation needed. The possible occurrence of such an event would be detailed in the Environmental Protection section of the contract specifications (not developed for feasibility study).
Containment of Trench Slurry - Displacement During Construction. Bentonite has a minimum hydration period and is stored in large Baker tanks until needed. Once construction begins, it is mixed in a container or small pond and pumped to the trench as it is excavated. When trench slurry levels drop, more slurry is added. As wall product is mixed and placed in the trench, fluid is displaced; however, if excavation and production occur in tandem, the level of trench slurry remains within a few feet of the top of trench throughout the day with minimum top off occurring. As the wall closes in towards its final stationing, trench slurry levels are no longer balanced by excavation and fill; the excess slurry will be pumped off the trench and disposed of offsite.
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San Joaquin County, CA Description of Final Alternatives LEVEE SLOPE RESHAPING (ALSO CALLED “GEOMETRIC FIX”) DESCRIPTION Levee reshaping involves grading high areas and/or placing additional soil in depressions and compacting it in order to meet USACE levee design criteria for side slopes and crown width. For the RP, the minimum crest width is 20 feet for major tributary levees and 12 feet for minor tributary levees. Existing levees with landside and waterside slopes as steep as 2H:1V (for every 2 feet of horizontal distance, there is a 1 foot increase in height) may be acceptable if slope performance is good and if stability analyses determine the factors of safety to be adequate. Otherwise, the landside and waterside slopes should have 3H:1V slopes.
Preparation
Prior to construction, the waterside levee crest edge would be cleared and grubbed and the crown and existing landside slope would be stripped to remove 0.5 to 1 foot of material (up to 2 feet) depending on local conditions.
Construction
To correct levee geometry, suitable material would be placed along the landside to provide minimum slope, required height and crest width to meet USACE levee design criteria. After construction, slopes would be hydro-seeded for erosion control.
The additional area added to the landside toe varies from 1 to 30 feet, depending on the existing width of the levee. The slope reshaping typical plan is shown in Figure 4-2. Slope reshaping and levee height fixes may require relocation of landside toe drains and ditches, which would be reestablished landward of the improved levee toe and would continue to function as they did before levee improvements were constructed.
Levee slope reshaping may require removal of erosion protection such as rock revetment. Upon completion of reshaping, erosion protection would be replaced.
Equipment
The equipment used would be similar to that used for levee raising.
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San Joaquin County, CA Description of Final Alternatives Figure 4-1: Cutoff Wall Typical Plan
Note that the landside easement (right side) shown would be the minimum easement; landside easements would range from 10 feet to 20 feet from the levee toe.
10’ Minimum
Clear Access
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San Joaquin County, CA Description of Final Alternatives
LEVEE RAISE (LEVEE HEIGHT FIX)
Description
To raise levees, borrow material would be added after cutoff walls and levee reshaping improvements are completed (Figure 4-2). Material would be spread evenly and compacted according to levee design plans.
The levee would be hydro-seeded once construction was completed. In some locations, the height could increase up to 5 feet; however, most raises would be 1.5 to 3 feet. An increase in levee height may require additional levee footprint area to meet design requirements.
Preparation
Prior to construction, the waterside levee crest edge would be cleared and grubbed, and the crown and existing landside slope would be stripped to remove 0.5 to 1 foot of material (up to 2 feet) if local conditions warrant. The levee raise involves scraping or ripping the existing levee and placing and compacting additional soil material in those areas.
Construction
Suitable material would be placed along the crown and landside of the existing levee, where needed, to provide the minimum slopes, required height and crest width that meet USACE levee design criteria. Fill materials would then be compacted to the design specification. The typical plan for a levee raise is shown in Figure 4-2.
Equipment
A hitched scraper, hitched discs or hitched ripper are examples of what might be used to loosen existing material in order to achieve a bond between new soil material and the existing levee. Other equipment likely to be used during the process would be a water truck, a grader, belly dump trucks, a bulldozer, a manual compactor or a sheep’s foot roller.
4.3.4 Seepage Berm
A seepage berm is typically built adjacent to the landside of the levee and consists of layers of sand, gravel and soil. The purpose is to control seepage flows and reduce the risk levee undermining during a high-water event. The seepage berm acts as a cap, controlling flow below the berm surface and allowing it to reach an exit location such that the undermining of levee soils is reduced or eliminated, thereby preventing boils and piping near the levee.
The seepage berm width could range from 100 to 200 feet from the landside toe of the levee (maximum width of 300 feet). It would be 5 feet thick at the toe of the levee and gradually slope downward to about 3 feet at the landside edge, with a 3:1 slope to ground level.
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San Joaquin County, CA Description of Final Alternatives Figure 4-2: Levee Reshaping and Levee Raise Typical Plan Note that the landside easement (right side) shown would be the maximum clear access easement; landside easements would range from 10 feet to 20 feet from the levee toe. Half levee degradation is generally not proposed unless a cutoff wall would be installed. Instead, an internal drain may be constructed between the existing levee materials and the new fill.
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San Joaquin County, CA Description of Final Alternatives Prior to construction, the landside area would be cleared and grubbed for the new berm, right of way and temporary easement. A layer of sand would be placed to help eliminate the movement of fine-grained materials from underneath the levee. Gravel would be placed on top of the sand to create a drainage layer to allow water to flow in a controlled manner and exit the face of the seepage berm to reduce pressure on the landside of the levee. A soil layer would be placed on top of the gravel to further reduce the risk of seepage flows. Filter fabric would be placed between the soil and gravel layer to avoid migration of the soil into the gravel, which could clog the gravel and reduce its ability to carry seepage flows. A typical plan for a seepage berm is shown on Figure 4-3.
NEW LEVEE
Description
This measure involves new construction to reduce flood risk to areas or to prevent waters from outflanking (flowing around the ends of the levees and entering the protected area) the levee system during high water events. Under Alternatives 7a, 8a and 9a, a new levee would be constructed on the upstream 0.75 mile of Duck Creek to tie the existing levee into the railroad berm on the north side of Duck Creek.
New Setback Levee with Cutoff Wall and Existing Levee Degrade. A new levee would be constructed to include a cutoff wall and would be used along the western portion of Fourteenmile Slough. The existing levee would be partially degraded (about half way) and a new levee constructed landward of the remnant existing. The land between the remnant levee and new levee would become a mitigation planting area to offset project environmental impacts. About 14 acres of habitat would be created between the existing levee and the VFZ of the new landside levee. The length of the offset area would be 1.33 miles and the width would vary from about 60 feet to 90 feet.
Preparation
The construction footprint would be cleared and grubbed and a new levee foundation excavated. An inspection trench would be excavated across the entire proposed centerline of the new levee. The trench depth would depend upon levee height, as required by USACE guidance and the State’s Urban Levee Design Criteria (ULDC). For the purposes of the impact analysis, a depth of 3 to 6 feet is assumed.
New Setback Levee with Cutoff Wall and Existing Levee Degrade. The area would be cleared and grubbed and material obtained from degrading the top half of the levee would extend up to 60 feet beyond the existing levee. It would be compacted such that the material forms an extension to the existing levee. The degraded material would be placed landward.
Construction
Construction of the new levee would conform to USACE levee design criteria, with suitable material placed in 6 to 8 inch lifts, moistened and compacted to specification until the design elevation is reached. A cutoff wall would be constructed through the new levee center, if needed, to prevent through and under seepage.
For any required erosion protection, quarry stone riprap would be applied to armor the levee's waterside slope. Fill material would be obtained and delivered using haul trucks. A gravel road would be constructed on the crown of the new levees. After construction, levee slopes would be reseeded with natural grasses to prevent erosion. A typical plan for a new levee with a cutoff wall is in Figure 4-4.
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San Joaquin County, CA Description of Final Alternatives
EROSION PROTECTION
Description
The new erosion protection would be placed either on the waterside of the levee or on the landside, above the waterline. The North Stockton erosion protection’s purpose is to protect the project from wind and wave run-up erosion that could occur if Delta levees west of the project levee were to fail. The purpose of the Central Stockton erosion protection on Duck Creek is to protect the landside from erosion that could occur if floodwaters moving from the south to the northeast were to wrap around the end of the project levee and back up against it. Although this would be the only new erosion protection, any existing riprap disturbed during construction would be replaced.
Construction
Riprap was used to describe erosion protection features and the associated impacts. Approximately 75,000 tons of imported quarry stone would be placed to a thickness of 2 feet along the landside to prevent wind wave erosion. A sand filter would also be placed prior to the riprap layer to prevent gravel instability and decreased erosion protection performance. In PED, other erosion protection methodologies besides riprap may be explored.
Equipment
A dump truck or belly dump is likely the predominant piece of equipment that would be used to transport the rock. A hydraulic excavator would be used to settle the rock into place. Rock can also be placed from a barge using a hydraulic excavator. A dozer may be necessary following the barge unloading to settle the rock into place.
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San Joaquin County, CA Description of Final Alternatives Figure 4-3: Seepage Berm Typical Plan
10’ Minimum
Clear Assess
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San Joaquin County, CA Description of Final Alternatives Figure 4-4: New Levee with Cutoff Wall Typical Plan
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San Joaquin County, CA Description of Final Alternatives
FLOODWALL
Floodwalls are an efficient, space-saving method for containing unusually high water surface elevations.
They are often used in densely developed areas with limited space. This measure would construct about 0.2 mile of sheet pile floodwall from the southern portion of Dad’s Point to high ground at Louise Park adjacent to the boat launch. The wall height would be an average of 3 to 4 feet above the ground surface. A metal cap may be placed on the top of the sheet pile or the sheet pile may be encased in concrete. The floodwall would be 5- to 8-inches wide.
Preparation
To begin construction, the area would be cleared, grubbed, stripped and excavated to provide space for the footing of the floodwall.
Construction
The floodwall would primarily be constructed from pre-fabricated materials, though it may be cast or constructed in place almost completely upright. Floodwalls mostly consist of relatively short elements, designed to disturb a minimal amount of waterside vegetation. The height would vary from 1 to 4 feet as required by water surface elevations. The waterside slope would be re-established to its existing slope and the levee crown would grade away from the wall and be surfaced with aggregate base.
NEW BRIDGES
Three bridges would be constructed over Mormon Channel Bypass to replace low water road crossings that are periodically inundated. This measure is included in Alternatives 9a and 9b and would include removing the existing road and grading the area to allow flood flows to move unimpeded from the Stockton Diverting Canal through the Mormon Channel Bypass and then into the San Joaquin River.
SEISMIC REMEDIATION
The Delta Risk Management Strategy (DRMS) conducted by Californian Department of Water Resources (DWR) in 2008 identified the vulnerability of San Joaquin Delta levees to seismically-induced cracking and slumping, which could lead to flooding particularly where levees are loaded every day. Site-specific liquefaction triggering analysis performed by USACE for the LSJRFS identified localized reaches that are vulnerable to liquefaction under earthquake loading from an event with a 0.005 probability of occurring in any year (recurrence interval of 200 years). Subsequent to USACE seismic evaluation DWR conducted liquefaction and deformation analysis in the LSJRFS study area using additional information from borings and cone penetration tests (CPTs). The following conclusions are based on a combination of USACE and DWR analysis.
Based on existing foundation data and analysis the northern-most corner of the Stockton North impacted area, which also experiences a daily load of 6 feet of water, is not susceptible to liquefaction and slope failure induced by a seismic event. The data on which this conclusion is based, however, is from the east side of Fourteenmile Slough. Although it is reasonable to expect that foundation conditions on the west side of Fourteenmile Slough are similar, there is some uncertainty since no investigations exist on the west side. A preliminary alternative was considered to fix in place on the east side and extend the existing Lincoln village levee to address flooding from the Delta. It was deemed unjustified because it required a longer length of levee to go around Fourteenmile Slough and it would require the acquisition of a large number of homes (well ATTACHMENT D 1099
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San Joaquin County, CA Description of Final Alternatives over 100). The levee on the west side with a closure structure for Fourteen mile Slough was the more costeffective solution.
Based on existing data and analysis the southern-most (southwest) corner of the Stockton North impacted area, which experiences a daily load of 5 feet of water, is susceptible to liquefaction and slope failure induced by a seismic event with a recurrence interval of 200 years. The vulnerable reach is located on the San Joaquin River just downstream of the confluence with the Calaveras River (Figure ES-1). This portion of the San Joaquin River is a deep water ship channel (DWSC) flanked by high steep levees which are tidally loaded to elevation 6 feet daily. The landside toe elevation is as low as 1 feet and portions of the Stockton North impact area are below elevation 0 (Figure 2-1). The daily load in terms of head above the landside levee toe is 5 feet and will increase with sea level rise since the Delta is connected to the Pacific Ocean. The population of Stockton North impact area is 83,000 people (Figure 3-18: North Stockton Residual Risk). The reach also includes the East Bay Municipal Utility District (EBMUD) water pipeline crossing of the DWSC. Seismically induced liquefaction and slope failure could flood the Stockton North impact area, close the Stockton DWSC, and sever the EBMUD water pipeline.
The DWR analysis cross section at Station 95+00 identifies a likely liquefiable sand layer 16 feet thick extending from elevation -15 to -31 feet and extending laterally into the ship channel. Stability analysis of the waterside slope using post-seismic strengths for the liquefiable layer (but no acceleration) results in a factor of safety of 0.85. Because the factor of safety is less than one the sand layer is expected to flow into the ship channel taking the levee with it; under the flow condition the deformed height of the levee cannot be predicted. The daily high tide of 6 feet could overtop the damaged levee or initiate a piping failure through cracks in the levee. Given these foundation conditions and potential consequences, the PDT determined that it was necessary to include seismic remedial measures for 5600 linear feet in the project description and baseline cost estimate in order to meet engineering requirements. No other segments requiring seismic mitigation have been identified.
Mitigation for liquefaction usually entails compacting, densifying, or encapsulating the liquefiable layer. The mitigation measure used for the baseline cost estimate encapsulates the liquefiable layer by constructing a series of cells using deep soil mixing. This mitigation measure is common to all of the alternatives accept the no action alternative. Because the liquefiable layer is well below normal river level direct excavation and compaction is not feasible. Another compaction method called deep dynamic compaction is not recommended because it involves dropping a large weight from a crane and the vibration could induce liquefaction and slope failure. Stone columns are a common method to densify liquefiable layers and relieve pore water pressure upward through the columns. The lack of confinement on the waterside would limit densification and seepage through the columns could impact levee performance. Stone columns are installed using vibration which could cause settlement of the levee during construction. Encapsulation by constructing deep soil mixing cells was selected as the best approach due to the narrow construction footprint between the deep water ship channel and the residential development and the disadvantages of the other methods considered.
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San Joaquin County, CA Description of Final Alternatives Description
This technique is meant to keep the levee from deforming or liquefying during seismic activity. It would be implemented to provide seismic stability to the Stockton Deep Water Ship Channel where it is vulnerable to liquefaction, retains a permanent pool, and protects the Brookside neighborhood as well as the East Bay Municipal Utility District water supply pipeline. It would involve installation of a grid of drilled soil-cement mixed columns (Figure 4-5). There would be a series of overlapping, DSM columns aligned longitudinally with and transverse to the alignment of the levee extending beyond the levee prism. This measure would also reduce risk of seepage and provide improved landside slope stability.
Construction
The crest of the levee would be reconstructed to comply with the USACE levee design criteria. A determination may be made during the future design that all the degraded material may not be necessary to extend the levee to the proposed toe. The proposed toe could be located along an imaginary line extending from the landward face of the proposed levee to existing grade. During the current feasibility planning, the maximum extent of the reconstruction berm is shown in order to show the maximum impacts that could occur.
DSM augers would be used to construct a continuous grouping of cells spaced equally in both longitudinal and transverse directions to the levee alignment (Figure 4-5). A hose attached to the auger would inject cement bentonite slurry into the soil, allowing for DSM. After construction is completed, the levee crest would be topped with a 6-inch aggregate road and the slopes would be hydro-seeded for erosion control.
The location of the individual columns and the pressures to be used during construction will be defined during PED, if the project is authorized and funded. Column locations will be placed to minimize chances that the soil-cement mixture would be released into the environment (frac-out).
Equipment
A truck mounted with a mechanical DSM auger, a cement bentonite equipment mixer and a pump delivery system would be used.
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives Figure 4-5: Seismic Remediation Typical Plan
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San Joaquin County, CA Description of Final Alternatives (this page intentionally left blank)
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San Joaquin County, CA Description of Final Alternatives
CLOSURE STRUCTURES
Description
This measure would include construction of closure structures at the mouth of backwater sloughs at Smith Canal and on Fourteenmile Slough to reduce flood risk. The Smith Canal structure would extend from the end of Dad’s Point to the right bank of the San Joaquin River at the Stockton Golf and Country Club. The Fourteenmile Slough closure structure would extend across Fourteenmile Slough about 0.3 miles west of Fivemile Slough. The closure structures would control back‐flooding from the San Joaquin River and Delta during high water events.
The proposed structure for Smith Canal would consist of a fixed sheet pile wall (about 800 feet long) with an opening gate sufficiently large to allow for the safe passage of boats and other watercraft. Fish and other aquatic organisms would be able to pass through these gates when they are open. The opening portion of the gate would be automated and may open upward or outward. The gate would be 50-feet wide and attached to a concrete foundation. A small building, about 400 square feet, would be built at the end of Dad’s Point, directly adjacent to the closure structures, designed to store equipment required to operate the gate. As needed, a sheet pile floodwall would be constructed adjacent to the control structures to tie the structures into the adjacent levee or high ground areas.
The elements discussed above are specifically for Smith Canal and are assumed to generally apply to the Fourteenmile Slough closure structure. During PED, further evaluation would be completed to confirm or adjust these assumptions.
Preparation
Construction of sheet pile walls on land would require that clearing and grubbing of vegetation for a 35- feet wide footprint. Survey markings could be expected post clearing and grubbing. Preparation for construction would require a working platform (barge) and a tug boat in order to move the barge around.
The survey equipment for use in and around water would likely be a laser guided system.
Construction
Construction would not require dredging, drag-lining or in-water excavation. The in-water work would be accomplished without use of a separate cofferdam. The cofferdam and permanent sheet pile are identical, except for the gate construction where the sheet pile will be cut away upon completion of the concrete structure. The “wing” structures supporting the operable gates and related floodwalls would permanently block a portion of each of these waterways.
The following are the details of the sheet pile installation and miter gate installation on Smith Canal. The closure structure on Fourteenmile Slough would be a scalable version of the Smith Canal, to be determined in PED. However, Fourteenmile Slough may require pumping capacity in order to evacuate water from the slough during high water events.
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San Joaquin County, CA Description of Final Alternatives For the dual sheet pile wall construction:
1. Two sheet pile walls would be parallel to each other and 20 feet apart. They would install the same way as a single sheet pile wall is installed. The south dual sheet pile would be installed during the first in-water construction season beginning June 30. Once the miter gate is operational, the north section of the dual sheet pile wall would be installed in the following year’s in-water construction season.
2. The space between the dual sheet piles would be dewatered for installation of cross ties, bracing and gated culverts between the two sheet pile walls.
3. Granular fill material would then be placed between the two sheet pile walls without dewatering up to 3 feet of the top of the dual sheet pile walls.
4. Total installation time for the dual sheet piles is about 4 months.
For the miter gate construction:
1. A metal sheet pile cofferdam is required to allow dry work to occur on the walls and foundation of the gate. The cofferdam sheet piles would be formed for the foundation of the gate structure (70 ft by 70 ft). This takes 3 weeks to install.
2. Once the coffer dam is installed, dewatering of the sheet pile would occur and a small amount of dewatering would continue during installation of the gate structure.
3. Concrete cylinder piles (24 inch diameter) would be driven inside the coffer dam using an impact hammer to provide support for the concrete floor and walls.
4. Reinforced concrete floor and walls would be formed and placed using the cylinder piles for support.
5. A metal gate would be attached to the concrete floor and walls. Installation of the gate foundation, walls and miter gate would take 6 months.
6. Two sides of the coffer dam would be used to form the walls of the gate structure. The remaining two sides that block the navigable openings of the gate would be cut by divers at the sides of the wall and top of the gate foundation to provide the necessary opening.
Equipment
The equipment necessary for work in the water would include a barge as a working platform for the installation process and a tug boat for the movement and correct placement of the barge. Once a desired location is established, an anchoring system would be necessary for the barge during installation of the sheet pile wall. The tug would remain nearby during the construction.
The installation of the sheet pile wall would require that a crane be assembled on the barge. A vibratory hammer would be installed at the end of the crane. Depending on the depth necessary for installation, a vibratory hammer may not have the driving power necessary for complete installation; an impact hammer may be needed in order to reach the depths necessary to fully install the sheet pile. Installation of the sheet pile wall on land will require the use of an impact hammer to get the walls to the proper depth.
The construction of the gate structure would require support piles to be installed for the foundation of the closure gate. The support piles would require that an impact hammer be used to drive the piles to the proper depth.
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives After the installation of the walls and piles, the barge would continue to be used to ferry construction workers and small equipment to various points to complete installation of the wall and the closure gate foundation. The platform for the closure gates would be a pre-cast, ready-to-install floor or the floor could be formed and concrete placed onsite. The walls could also be pre-cast or formed and placed onsite. The equipment and materials needed for construction would be ferried to the site.
The elements discussed above are specifically for Smith Canal and are assumed to generally apply to the Fourteenmile Slough closure structure. During PED, further evaluation would be completed to confirm or adjust these assumptions.
CONTROL STRUCTURE AND BYPASS CHANNEL
This measure involves re-watering Old Mormon Slough (below the Stockton Diverting Canal) as a FRM bypass (Mormon Channel Bypass). Installing a diversion structure on the left downstream bank of the Stockton Diverting Canal would divert up to 1,200 cfs down Mormon Channel Bypass. The flows diverted would otherwise go through the Stockton Diverting Canal to the Lower Calaveras River and out into the San Joaquin River/Stockton DWSC. The design would divert the maximum flow that could be handled by the channel without levees or floodwalls. Implementation of these measures would reduce water levels during flood events on the Stockton Diverting Canal and the Calaveras River, as well as provide some ER benefits to the Mormon Channel Bypass.
Channel improvements would be required under this measure. The Mormon Channel Bypass improvements would begin at the Stockton Diverting Canal and would continue downstream approximately 6.3 miles.
Most of the low-water crossings would be removed or replaced with bridges to maintain service during flood operations and reduce head losses at the crossings. In addition, several reaches must be enlarged by removing fill and encroachments in order to reestablish channel capacity. Other work would include construction of a floodwall around an existing building and installation of two additional culverts at the Southern Pacific Railroad (SPRR) crossing.
The control structure would be a box culvert constructed in the existing Stockton Diverting Canal levee to divert flows from the Stockton Diverting Canal to the Mormon Channel Bypass. A 12-foot radial gate would be used to control Mormon Channel flows to no greater than 1,200 cfs. The gate would be automatic and operate based on real-time gage flows. A plan of the proposed control structure is in Figure 4-6.
Figure 4-6: Mormon Channel Bypass Control Structure
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives
4.3.11 JET GROUTING
Description
Jet grouting is typically used in constructing a cutoff wall to access areas other methods cannot. It is typically a spot application rather than a large scale treatment. Jet grouting would be used around existing utilities not proposed for removal and at bridges along levees in the project area. It involves injecting fluids or binders into the soil at very high pressure. The injected fluid can be grout; grout and air; or grout, air and water. Jet grouting breaks up soil and, with the aid of a binder, forms a homogenous mass that solidifies over time to create low permeability.
Preparation
To provide a wide enough working platform on the crown, the upper portion of some segments of levee may require degradation with a paddle wheel scrapper. Material would be scraped and stockpiled nearby.
Hauling would involve scraper runs to the staging area and grout, bentonite and water deliveries to the batch plant.
Construction
To initiate jet grouting, a borehole would be drilled through the levee crown and foundation to the required depth (to a maximum of 130 feet) by rotary or rotary-percussive methods using water, compressed air, bentonite or a binder as the flushing medium. A high pressure pump would convey grout, air and/or water through pipelines to the drill string, to a set of nozzles located just above the drill bit. Smaller equipment could be used in combination with the single phase–fluid system and could be permanently trailer-mounted to permit efficient mobilization and easy movement at the job site. During this process, the drill string is rotated and slowly withdrawn. Use of double, triple and superjet systems create eroded spoil materials that would be expelled out of the top of the borehole. The spoil material would contain significant grout content and could be used as a construction fill.
Jet-grouted columns range from 1 to 16 feet in diameter and are interconnected to form cutoff barriers or structural sections. One construction crew, consisting of a site supervisor, pump operator, batch plant operator, chuck tender and driller, can construct 2 6-feet-diameter, 50-foot columns per day consisting of 100 cubic yards of grout injected per 8-hour shift. Ideal conditions would be characterized by no technical issues such as loss of fluid pressure, breakdown of equipment or subsurface obstructions occurring at either the batch plant or the drilling site.
Equipment
Equipment required for jet grouting consists of a drill rig fitted with special drill string; a high pressure, high flow pump; an efficient batch plant with sufficient capacity for the required amount of grout and water; supporting generators; air compressors; holding tanks; water tanks; and bulk silos of grout typically used to feed large mixers.
ENCROACHMENTS
Utility encroachments such as structures, certain vegetation, power poles, pump stations and levee penetrations (e.g., pipes, conduits, cables) would be brought into compliance with USACE policy or removed depending on type and location. This would include the demolition, relocation or reconstruction as appropriate (or retrofit to comply with standards). Utility replacements would occur via (1) a surface line over the levee prism or (2) a through-levee line equipped with positive closure devices.
ATTACHMENT D 1107
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives No real property has been definitively identified for acquisition at this time. In the PED phase of the project following Congressional authorization, site-specific analysis would be conducted prior to construction to determine specific impacts to include encroachment removal. In preparing real estate acquisition boundaries for the NFS, encroachment removal will be avoided to the greatest extent possible consistent with the real estate requirements for the project.
ALTERNATIVES
ALTERNATIVE 1 – NO ACTION
Under No Action, USACE would not participate in improvements to the existing FRM in the study area.
Although State or local agencies would likely repair area levees in the future to meet Federal (FEMA) or State (SB 5 200-year protection) flood protection obligations, this alternative assumes that FRM measures would not be implemented and that the current level of risk would continue. This risk, as represented in the study analysis area, would leave both residents and property in and near the Cities of Stockton, Lathrop and Manteca vulnerable to flooding.
In response to major floods in the early 1950s, USACE constructed several dams, miles of levees and other features in and near the study area as part of the Lower San Joaquin River and Tributaries project. Since then, the engineering performance and potential reliability of these projects were reexamined due to greater understanding of operational processes, including through and under seepage, slope stability, overtopping and erosion. Under No Action, these processes would continue and likely become worse, increasing the risk of future levee failure during high flows.
Climate change also appears to be affecting worldwide temperatures and seasonal climate patterns.
Projections show rises in sea level and changes in inland climate patterns that could result in higher, future water-surface elevations in the San Joaquin River and tributaries. An estimated 235,000 residents and $28.7 billion in damageable property would continue to be at risk of unexpected levee failure and flooding in the study area.
Existing environmental resources, particularly native vegetation, wildlife, special status species and water quality are also at risk from levee failure and flooding. Adverse effects could include future loss or damage to terrestrial and/or aquatic habitats.
ALTERNATIVES 7A (RECOMMENDED PLAN) AND 7B – NORTH AND CENTRAL
STOCKTON, DELTA FRONT, LOWER CALAVERAS RIVER, SAN JOAQUIN RIVER LEVEE IMPROVEMENTS AND RD 17 LEVEE IMPROVEMENTS (ALTERNATIVE 7B ONLY)
Under Alternatives 7a (RP) and 7b, levee improvements consist of measures described in Section 4.3.
Alternative 7a is also shown on Figure 3-8. Alternative 7b is shown on Figure 3-9. Tables 4-2 through 4-4 summarize the measures proposed per separable area and waterway.
ATTACHMENT D 1108
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives Table 4-2: Action Alternatives Measures by Waterway—North Stockton Action Alternatives
Waterway Reach Proposed Measure(s) 7a 7b 8a 8b 9a 9b
Mosher Slough Shima Tract to Thornton
Road
Cutoff wall
Levee height fix (sea level
rise)
X X X X X X
Shima Tract Mosher Slough to
Fivemile Slough
Cutoff wall
Erosion protection (landside) X X X X X X
Fivemile Slough Shima Tract to
Fourteenmile Slough
Cutoff wall
Erosion protection (landside) X X X X X X
Fourteenmile
Slough
Fivemile Slough to
Proposed Closure
Structure
Slope Reshaping
Levee height fix (sea level
rise)
Erosion protection (landside)
X X X X X X
Fourteenmile
Slough
Approximately 1,500 feet
west of Fivemile Slough Closure Structure X X X X X X
Fourteenmile
Slough
Approximately 1,250 feet
southeast setback out
from proposed closure
structure
Levee height fix (sea level
rise)
Erosion protection (landside)
X X X X X X
Fourteenmile
Slough
From setback cut south to
Tenmile Slough
With Setback
Slope Reshaping
Erosion protection
(landward)
X X X X X X
Tenmile Slough Fourteenmile Slough to
March Lane
Cutoff wall
Slope Reshaping
Erosion protection
(waterside)
X X X X X X
Tenmile Slough
March Lane to West
March Lane/Buckley
Cove Way
Seismic Fix
Slope Reshaping
Erosion protection
(waterside)
X X X X X X
Tenmile Slough/
Buckley Cove
Marina/ San Joaquin
River
West March
Lane/Buckley Cove
Way/to Calaveras River
Seismic Fix
Slope Reshaping X X X X X X
Calaveras River –
Right/North Bank
San Joaquin River to
North El Dorado Street Cutoff wall X X X X X X
Calaveras River –
Right/North Bank
North El Dorado Street to
railroad tracks
Cutoff wall
Slope Reshaping
Height Fix
X X
Calaveras River –
Right/North Bank
Railroad tracks to
approximately
Cherryland Avenue
Cutoff wall X X
Table 4-3: Action Alternatives Measures by Waterway—Central Stockton Waterway1 Reach Proposed Measure(s)
Action Alternatives
7a 7b 8a 8b 9a 9b
Calaveras River –
Left/South Bank
San Joaquin River to
approximately I-5 Cutoff wall X X X X X X
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San Joaquin County, CA Description of Final Alternatives Calaveras River –
Left/South Bank
Approximately I-5 to
approximately North
Pershing Avenue
Cutoff wall
Slope Reshaping X X X X X X
Calaveras River –
Left/South Bank
Approximately North
Pershing Avenue to
approximately El Dorado
Street
Cutoff wall X X X X X X
Calaveras River –
Left/South Bank
Approximately El Dorado
Street to the Stockton
Diverting Canal
Cutoff wall X X
Stockton Diverting
Canal
Calaveras River to Old
Mormon Slough Cutoff wall X X
San Joaquin River
From approximately 2,100
feet upstream of the
Calaveras River to the
proposed Smith Canal
Closure Structure
Cutoff wall
Levee height fix (sea
level rise)
X X X X X X
Smith Canal
At the mouth of the canal
between Stockton Golf and
Country Club and Dad’s
Point
Closure Structure X X X X X X
Smith Canal
Dad’s Point from the Closure
Structure to approximately
375 feet down Monte Diablo
Avenue
Floodwall X X X X X X
Old Mormon
Slough
Port of Stockton to Stockton
Diverting Canal
Diversion structure
Channel improvements
Flood Bypass channel
X X
San Joaquin River
Railroad bridge just
upstream of the Port of
Stockton to Burns Cutoff
Cutoff wall
Slope Reshaping X X X X X X
San Joaquin River Burns Cutoff to French
Camp Slough Cutoff wall X X X X X X
French Camp
Slough –
Right/North Bank
French Camp Slough
confluence with the San
Joaquin River to
approximately 500 feet
southwest of I-52
Cutoff wall X X X X X X
Duck Creek 500 feet past I-5 cross to
approximately Odell Avenue New levee X X X
Duck Creek Approximately Odell
Avenue to McKinley Avenue
Cutoff wall
Levee reshaping
Levee Height Fix
X X X
1 Note that for the purposes of the impact assessment in Chapter 5, all improvements to levees on the Calaveras River are considered as part of Central Stockton. This was in recognition of the importance of considering the Calaveras River, including both banks, as an ecologically meaningful whole.
2 Note that specific sections of this reach have been repaired by RD 404 and will be excluded from the RP.
ATTACHMENT D 1110
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San Joaquin County, CA Description of Final Alternatives Table 4-4: Action Alternatives Measures by Waterway—RD17 Waterway Reach Proposed Measure(s)
Action Alternatives
7a 7b 8a 8b 9a 9b
French Camp
Slough –
Left/South
Bank
San Joaquin River to
approximately 600
feet southeast of
Carolyn Weston
Boulevard
Cutoff wall X X X
San Joaquin
River
French Camp Slough
to approximately Dos
Reis Road
Cutoff wall
Slope Reshaping
Height fix
X X X
San Joaquin
River
Approximately Dos
Reis Road to the
levee access road at
the northern
termination of
Lathrop Road
Seepage berm
Levee reshaping
Height fix
X X X
San Joaquin
River
From the levee access
road at the northern
termination of
Lathrop Road to the
levee access road at
the southern
termination of
Lathrop Road
Cutoff wall
Slope Reshaping
Height fix
X X X
San Joaquin
River
From the levee access
road at the southern
termination of
Lathrop Road cutting
off the oxbow due
south
New levee
Erosion protection X X X
San Joaquin
River
From the new levee
to approximately
Chiavari Way
Seepage berm
Levee reshaping
Height fix
X X X
San Joaquin
River
From Chiavari Way
to the existing
termination of the tie
back levee
Cutoff wall
Slope Reshaping
Height fix
X X X
San Joaquin
River
From the existing
termination of the tie
back levee to
approximately South
Tinnin Road
New levee X X X
San Joaquin
River
From approximately
Woodward Road to
the termination of the
new tie back levee
Erosion protection X X X
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Final Feasibility Report - Chapter 4 - January 2018
San Joaquin County, CA Description of Final Alternatives North Stockton Area
Levee Improvements
The North Stockton area includes improvements to the Mosher Slough south levee, Shima Tract east levee, Fivemile Slough/Fourteenmile Slough north levee, Fourteenmile Slough west levee, Tenmile slough east levee, Calaveras River north/right levee and San Joaquin River east levee. For the purposes of the impact assessment in Chapter 5, Calaveras River improvements are considered within Central Stockton. The measures proposed to improve the levees include cutoff walls, setback levee with cutoffwall and existing levee degrade, levee height fixes, erosion protection, and slope reshaping. For the Calaveras River, 4.25 miles of the north bank (to approximately El Dorado Street) would be improved with a combination of cutoff walls, slope reshaping and height fixes. In addition, a closure structure would be installed across Fourteenmile Slough, 1,500 feet west of Fivemile Slough. These measures are described in Section 4.3.
The locations of each fix are shown on Figures 3-8 and 3-9 and summarized in Table 4-2. For the purposes of the impact assessment in Chapter 5, the Calaveras River north/right bank improvements are considered together with the Calaveras River south/left bank improvements under Central Stockton.
Closure Structure on Fourteenmile Slough
In addition to the levee improvement measures, there is also a closure structure proposed for Fourteenmile Slough. It would be located across Fourteenmile Slough from the Fivemile Slough/Fourteenmile Slough north (right) levee to the Fourteenmile Slough south/west (left) levee and consistent with the design described in Section 4.3.10.
This portion of the study area has a high risk of seismic events. Also, operation of the closure structure would limit water saturation levels in during high water, which would reduce the risk of levee damage from both seismic and high water events.
Central Stockton Area
Levee Improvements
The Central Stockton area includes levee improvements to the Calaveras River, San Joaquin River, Smith Canal and French Camp Slough. For the Calaveras River, 3.3 miles of the south bank (to approximately Pacific Street) would be improved with a combination of cutoff walls, slope reshaping and height fixes, described in Section 4.3. The locations of each fix are shown on Figures 3-8 and 3-9 and summarized in Table 4-3. For the impact assessment in Chapter 5, Calaveras River north/right bank improvements are considered under Central Stockton.
Closure Structure on Smith Canal and Floodwall on Dad’s Point In addition to levee improvements, a closure structure would be installed across the mouth of Smith Canal from the San Joaquin River east levee at Brown’s Island to the end of Dad’s Point. A floodwall (about 3 to 5 feet high) would also be constructed on Dad’s Point to tie the closure structure into the high ground on the shoreline. The design would be consistent with the measure described in Section 4.3. The closure structure would prevent inflow into Smith Canal during high water levels in the Delta and San Joaquin River, limiting the level and duration of water saturation and reduce the risk of levee damage or failure. It is anticipated that adequate warning would be provided in order to minimize inconveniences to recreational boat traffic.
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San Joaquin County, CA Description of Final Alternatives New Levee on Duck Creek (Alternative 7a only)
To reduce the risk of flooding, a new levee would be constructed on Duck Creek. This levee would be an extension of the existing French Camp Slough north levee and extend three-fourths of a mile from French Camp Slough to the rail yard. The new levee would be consistent with the measures described in Section
4.3. RD 17 Area (Alternative 7b only)
Levee Improvements
The RD 17 area includes levee improvements to the French Camp Slough south levee and the San Joaquin River east levee. The measures proposed to improve the levees in the RD 17 area, described in detail in Section 4.3, include cutoff walls, levee height fixes, seepage berms, new levees, erosion protection and slope reshaping. The locations of each fix are shown on Figure 3-9 and summarized in Table 4-4.
New Levees on Oxbow Cutoff and Tie-Back
The work in RD 17 would include construction of two new levees; the oxbow cutoff levee and the southern tie-back levee. The oxbow cutoff levee is proposed for the San Joaquin River east levee at Old River, negating the need to improve a much longer reach of existing levee around the perimeter of the oxbow; however, the existing levee would remain in place. The new levee would be designed as described in Section 4.3 and is shown on Figure 3-9.
The southern tie-back levee would be constructed to extend the existing tie-back levee on the south end of RD 17 to prevent 200-year floodwaters from outflanking the existing levees. The extension would combine with repairs or improvements to the existing tie-in levee to meet current standards. The new levee would be designed consistent as described in Section 4.3 and is shown on Figure 3-9.
ALTERNATIVES 8A AND 8B – NORTH AND CENTRAL STOCKTON, DELTA FRONT,
LOWER CALAVERAS RIVER, SAN JOAQUIN RIVER, STOCKTON DIVERTING CANAL LEVEE IMPROVEMENTS, AND RD 17 LEVEE IMPROVEMENTS
(ALTERNATIVE 8B ONLY)
Alternatives 8a and 8b would include the same levee improvements as Alternatives 7a and 7b, respectively and would also include additional improvements along the Lower Calaveras River and Stockton Diverting Canal. As is the case for each of the action alternatives, the Calaveras River improvements are addressed within Central Stockton in Chapter 5. The location of each fix for Alternative 8a is shown in Figure 3-10.
For Alternative 8b, the location of each fix is shown in Figure 3-11. Tables 4-2 through 4-4 summarize the measures for Alternatives 8a and 8b.
North Stockton Area
Levee Improvements
Improvements for Alternatives 8a and 8b would be the same as for 7a and 7b, respectively.
Fourteenmile Slough Closure Structure
The closure structure and related floodwall for Alternatives 8a and 8b would be the same as for 7a and 7b, respectively.
ATTACHMENT D 1113
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San Joaquin County, CA Description of Final Alternatives Central Stockton Area
Levee Improvements
The levee improvements for Alternatives 8a and 8b would include the same measures as for 7a and 7b, respectively. In addition, cutoff walls would be installed along another reach of the Lower Calaveras River, and along the Stockton Diverting Canal to the Old Mormon Slough, as shown on Figures 3-10 and 3-11.
Installation of cutoff walls would be consistent with Section 4.3.
Smith Canal Closure Structure and Floodwall on Dad’s Point The closure structure and related floodwall for Alternatives 8a and 8b would be the same as for 7a and 7b, respectively.
New Levee on Duck Creek (Alternative 8a only)
The new levee for Alternative 8a would be the same as for 7a.
RD 17 Area (Alternative 8b only)
Levee Improvements
Improvements for Alternative 8b would be the same as for 7b.
New Levees
New levees for Alternative 8b would be the same as for 7b.
ALTERNATIVES 9A AND 9B – NORTH AND CENTRAL STOCKTON, DELTA FRONT,
LOWER CALAVERAS RIVER, SAN JOAQUIN RIVER LEVEE IMPROVEMENTS, MORMON CHANNEL BYPASS AND RD 17 LEVEE IMPROVEMENTS (RD 17 ONLY) Alternatives 9a and 9b would include the same levee improvements as 7a and 7b, respectively, and would also include construction of a flood bypass and diversion structure in Old Mormon as shown in Figure 4-6.
Tables 4-2 through 4-4 summarize the measures for Alternatives 9a and 9b.
North Stockton Area
Levee Improvements
Improvements for Alternatives 9a and 9b would be the same as for 7a and 7b, respectively.
Closure Structure on Fourteenmile Slough
The closure structure for Alternatives 9a and 9b would be the same as for 7a and 7b, respectively.
Central Stockton Area
Levee Improvements
Improvements for Alternatives 9a and 9b would be the same as for 7a and 7b, respectively.
Closure Structure on Smith Canal and Floodwall on Dad’s Point The closure structure for Alternatives 9a and 9b would be the same as for 7a and 7b, respectively.
ATTACHMENT D 1114
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San Joaquin County, CA Description of Final Alternatives New Levee on Duck Creek (Alternative 9a only)
The new levee for Alternative 9a would be the same as for 7a.
Mormon Channel Flood Bypass
Alternatives 9a and 9b would include construction of a diversion structure and improvement to the Old Mormon Slough to function as a flood bypass, allowing 1,200 cfs of flood flows to be diverted to the Stockton Diverting Canal. The control structure and channel improvements are described in Section 4.3.
Mormon Slough’s course extends in a general southwesterly direction from Bellota to the Stockton Diverting Canal flow diversion structure. The structure diverts all flood flows to the diverting canal, which discharges into the Calaveras River. The Mormon Slough below the diverting dam is referred to locally as Old Mormon Slough or Mormon Channel. The source of flow in Old Mormon Slough is the local tributary area downstream of the diversion structure.
Before construction of the Stockton Diverting Canal, Mormon Channel was connected to Mormon Slough and was perennial in most years. Today, the channel receives local storm water runoff and intermittently contains water.
Reintroducing flood flows to Old Mormon Slough by establishing the Mormon Channel Bypass would involve construction of a diversion structure at the confluence of Old Mormon Slough with the Stockton Diverting Canal and excavation within Mormon Channel to establish the channel as Mormon Slough Bypass. This would likely improve the conditions and health of the remaining vegetation and encourage expansion of the riparian vegetation along much of this channel.
The Mormon Channel Bypass control structure includes a tainter gate that would be operated to divert water into the channel. The gates would likely be operated every 2 years. The amount of water and duration of diverted flows would be adjusted according to the total flows moving through the system. The estimated operation of the structure is shown in Table 4-5.
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San Joaquin County, CA Description of Final Alternatives Table 4-5: Estimated Operations of the Mormon Channel Bypass Control Structure Frequency Event
Stockton Diverting
Channel Flows
Mormon Bypass
Flows
Average Length of
Operations
50% ACE Event
(1/2 year) 3,740 cfs 0 cfs 0 days
20% ACE Event
(1/5 year) 8,254 cfs 1,064 cfs 4 days
10% ACE Event
(1/10 year) 8,452 cfs 1,200 cfs 5 days
4% ACE Event
(1/25 year) 10,720 cfs 1,200 cfs 8 days
2% ACE Event
(1/50 year) 11,513 cfs 1,200 cfs 9 days
1% ACE Event
(1/100 year) 13,613 cfs 1,200 cfs 11 days
0.5% ACE Event
(1/200 year) 14,004 cfs 1,200 cfs 12 days
0.2% ACE Event
(1/500 year) 17,236 cfs 1,200 cfs 14 days
RD 17 Area (Alternative 9b only)
Levee Improvements
Improvements for Alternative 9b would be the same as for 7b.
New Levees
The new levees for Alternative 9b would be the same as for 7b.
CONSTRUCTION DURATION AND CONSTRUCTION FOOTPRINT (INCLUDING
STAGING, BORROW AND DISPOSAL)
CONSTRUCTION SCHEDULE
Overall Schedule and Sequencing
For planning purposes, construction is estimated to begin Delta Front levee in 2025 and is expected to last approximately five years, concluding in 2029. This is an estimated schedule, subject to Congressional authorization and appropriation of funds for the project. Construction in North Stockton is estimated to begin in 2027 and last five years, ending in 2031. The Central Stockton area would begin construction in 2030 and last four yers, ending in 2034. Construction of the full project would take 14 years if optimal funding is available.
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San Joaquin County, CA Description of Final Alternatives Annual Work
For Central Stockton, the work averages out to 3 miles of slurry cutoff wall, 0.75 of a mile of geometric improvements and a 0.5 mile of new levee construction per year. During the 3 year span, a closure gate would be constructed for Smith Canal, but would likely be accomplished mainly over 2 summers. For North Stockton, the work averages out to 1.25 miles of slurry cutoff wall, 0.5 mile of geometric improvements, three-eighths of a mile of seismic remediation and three-fifths of a mile of rock revetment per year.
Construction Pace. For work of this type, the expected pace of construction is generally estimated to be:
A levee 10-feet high and one mile long can be raised 1-foot in 3.5 days, not including mobilization and demobilization. A similar section of levee can be raised 2-feet in 7 days. A levee 18-feet high and one mile long can be raised 1-foot in 5.5 days, not including mobilization and demobilization. A similar section of levee can be raised 2-feet in 11.5 days.
Construction Timing. Construction would conform to all applicable State and Federal laws and would generally occur on the San Joaquin River from the middle of July through the end of October. For other rivers, streams and sloughs, construction would occur from the middle of April through the end of October.
Construction Intensity. Existing levee work is considered low to moderately intensive. New levee work and vibratory equipment for sheet pile are likely classified as moderately intense. Impact hammer use for sheet pile work would be considered high intensity. USACE may issue construction specifications requiring vibration monitoring associated with the use of impact hammers.
TEMPORARY AND PERMANENT EASEMENTS
For each action alternative, Table 4-6 shows the construction footprint, O&M easements and the construction duration required, including the footprint of the existing levee plus the waterside and landside easements. The easements identified in Table 4-6 are permanent easements that would be used during construction and maintained permanently for O&M, including vegetation management within the VFZs (15 feet waterside and the appropriate 10 to 20 foot easement landside of the levee toe).
Table 4-6: Construction and Easement Footprints (Structural Features), Construction and O&M Easements and Construction Duration
Alternatives
Construction 7a 7b 8a 8b 9a 9b
Construction footprint (ac) 158 367 219 428 190 402
Waterside 15-foot easement (ac) 42 76 62 95 42 76
Landside 20-foot easement1 (ac) 56 101 82 126 56 101
New levee easement (ac) 4 38 4 38 4 38
Construction duration (years) 14 15 12 15 12 15
1 Note that the minimum landside easement for existing Federally-authorized levees is 10 feet.
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San Joaquin County, CA Description of Final Alternatives Construction Easements
Access to the levee toe would be provided in all areas where construction is occurring on the levees. Either a 10 foot (minimum) or a 15 foot (maximum) landside access easement would be provided wherever levee remediation is completed as a result of this project.
Calaveras and Mosher Slough. Levee strengthening along portions of lower Calaveras and Mosher Slough would likely not be able to seek sufficient additional Temporary Work Area Easements (TWAE) due to land constraints from existing development. Much of the work would require that mobilizations and stockpiling occur at offsite temporary staging areas that are yet unknown.
Obtaining a Temporary Work Area Easement (TWAE) would likely be sought as the permanent easement is only 10-feet from the landside toe of the levee, which is expected to be insufficient. Depending on the type of construction work, the total easement required during construction could be between 20 and 30 feet.
If the project is authorized and funded by Congress, additional design work during PED would clarify easement requirements. Permanent easements would be necessary for areas where a levee raise is planned due to the effect of pushing the landside toe out when requiring proper geometric shaping.
O&M Easements
For levees that are currently part of the Federally authorized FRM project, a minimum permanent landside toe clear easement of 10 feet is required. For levees that are being brought into the Federally authorized project as a result of the RP, a minimum permanent landside toe clear easement of 15 feet is required. For both new and existing levees in the LSJRFS, a minimum permanent waterside easement of 15 feet is required.
STAGING AREAS
Construction staging and access for equipment and materials would take place within the landside project easements (10 to 20 feet landward of the levee toe) where practical and on publicly owned lands or on offsite areas where the NFS would negotiate the temporary use of private lands for this purpose. For certain reaches on the Lower Calaveras River, where a waterside earthen bench is present, staging could take place on either the landside or waterside of the levees; however, waterside use would be restricted to the approved construction season and mandatory environmental safeguards strictly enforced. The actual size, quantity and location of these temporary sites are dependent upon the extent of the construction project phase. For the purposes of evaluating impacts, it was estimated that 1 acre of staging area would be required for every mile of levee construction. The maximum area needed for Alternatives 7a, 8a and 9a would be 33 acres.
The maximum area needed for Alternatives 7b, 8b and 9b would be 36 acres. In addition to equipment, materials that may be in the staging areas include soil, rock and slurry batch plants.
Staging areas for construction of the closure structures on Fourteenmile Slough and Smith Canal would be adjacent to the levees on either side of the closure structures. Portions of the Buckley Cove, Louis Park and Dos Reis Park parking lots could be used for staging, potentially affecting normal use of boat ramps and disrupting passive recreational opportunities during the construction season(s).
BORROW MATERIAL AND SITES
A maximum of 1.8 million cubic yards (cy) of borrow material could be required to construct the entire project. The RP, Alternative 7a, would require a maximum of 1.4 million cy of borrow material and could require 138 acres of borrow lands. Table 4-6 shows the anticipated amount of borrow material required to construct each alternative. Because this project is in the preliminary stages of design, detailed studies of each alternative’s borrow needs have not been completed. For purposes of NEPA/CEQA, these material estimates will be used to evaluate effects on resources. Actual volumes to be exported from any single site ATTACHMENT D 1118
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San Joaquin County, CA Description of Final Alternatives would be adjusted to match final demands for fill. If the project is authorized and funded, detailed evaluation of borrow requirements, identification and detailed technical evaluation of potential sources, would be completed during PED, including appropriate literature review, site visits, informal consultation with resource agencies and surveys to determine the presence or potential presence of Federally-listed species or their designated critical habitat. Potential sites with listed species occurrences or with the potential for occurrences would be avoided.
Sufficient quantities of appropriate borrow materials are available within 25 miles of the project. To the extent feasible, material would be obtained from a licensed, permitted facility that meets all Federal and State standards and requirements. In addition, many acres of farmland and vacant land exist near the project and borrow could be obtained from these lands. Lands closest to the construction sites would be evaluated for availability and suitability before evaluating lands further from the project. Additionally, site selection would be based on the least environmentally damaging options, the ability to remove and transport the material and economic feasibility. It is assumed that material would be obtained from willing sellers.
The excavation limits on the sites would be in accordance with local regulations and provide a minimum buffer of 50 feet from the edge of the borrow site boundary. From this setback, the excavated slope from existing grade down to the bottom of the excavation would be no steeper than 3H:1V. Excavation depths from the sites would be determined based on need, available suitable material and local groundwater conditions. The sites would be stripped of topsoil material and excavated. Once material is extracted, topsoil would be replaced and sites would be returned to their pre-project or proposed condition when possible and in accordance with the necessary Reclamation Plan.
Any borrow activities would be subject to the Surface Mining and Reclamation Act (SMARA) of 1975 (Public Resources Code, Sections 2710-2796). The SMARA requirements apply to anyone, including State government agencies, engaged in surface mining operations in California (including those on Federally managed lands) that disturb more than 1 acre or remove more than 1,000 cy of material. This includes, but is not limited to, prospecting and exploratory activities, dredging and quarrying, streambed skimming, borrow pitting and the stockpiling of mined materials. At the time the borrow sites are identified, a detailed Reclamation Plan would be developed and appropriate financial assurances would be provided to ensure that each borrow area greater than 1 acre would be restored in a timely manner. SMARA permitting for borrow sites would be at the discretion of the State Mining and Geology Board (SMGB) and would require future CEQA documentation, with the SMGB as CEQA Lead Agency.
Table 4-7: Estimated Borrow Material and Lands Required for Each Alternative Alternatives
Borrow 7a 7b 8a 8b 9a 9b
Amount of borrow
material needed (cy) 1,406,000 3,869,000 1,807,000 4,270,000 1,406,000 3,869,000 Estimated borrow
lands needed (acre) 138 394 266 450 138 394
DISPOSAL MATERIALS AND SITES
Construction of the closure structures on Fourteenmile Slough and Smith Canal would require dredging and removal of less than 1,000 cy of material from the project site. Some of these materials would be used to construct other project features. The remaining removed material would be hauled offsite and disposed of at an approved site in the vicinity of the project.
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San Joaquin County, CA Description of Final Alternatives Suitable materials removed from the levees would temporarily be placed adjacent to the levee landside and returned to the levee as the remediation is completed. Alternately, materials would be moved to another levee segment for use in constructing that segment. Materials unsuitable for reuse would be removed to commercial and local disposal sites.
POST-CONSTRUCTION OPERATION AND MAINTENANCE
Once project construction is complete, it would be turned over to the CVFPB with an updated O&M manual in accordance with the executed Project Partnership Agreement (PPA) for construction. The PPA is signed before construction begins. Following construction, the NFS would be responsible for continued O&M of the project consistent with the new and/or amended O&M manuals, also referred to as Operation, Maintenance, Repair, Replacement and Rehabilitation (OMRR&R) Manuals, which specify requirements for operating and maintaining the project.
Levees
Levees should be maintained to the as-built condition in perpetuity or as long as the PPA is in effect. This means that the levee should maintain a consistent shape, side slopes, height and composition to when the levee is constructed. If the levee settles to a lower height or the slopes of the levee cause a loss or material and steepened slopes, the NFS is expected to return the levee to the as-built lines and grade. If the levee erodes due to water moving across the face or wind and wave run-up, the levee should be restored to the as-built condition and the slope protected against future erosion with stone riprap or other means. Holes or burrows into the levee caused by animals should be properly backfilled and measures taken to exterminate burrowing animals. The vegetation on the levee should be maintained as proposed in Section 3.3. The grasses on the slopes and easement area should be maintained to 12” in height or less, unless covered by an approved variance, to allow visibility and accessibility of the levee slope and toes.
Access roads to and along the levee as well as the levee crown should be maintained to the as-built condition ensuring that the crown is sloped to drain and the access roads are sloped to prevent ponding, allowing allweather access. The NFS will be responsible for making sure encroachments do not occur within the right of way of the project that might endanger efficient functioning of the levee. Lastly, the cutoff walls, jet grouting and seismic remediation measures will be installed within the levee section and sometimes deep into the levee foundation. These features will not be visible from the ground surface following construction.
O&M of these features are to ensure that they remain in place and are not penetrated by encroachments or other ground disturbing activities.
Floodwalls
Floodwall maintenance is very similar to the concept of levee maintenance: keep the floodwall in the asbuilt condition in perpetuity or as long as the project partnership agreement is in effect. The NFS should ensure that the floodwall does not settle or shift from its constructed position, which could impact the effective height of the wall or the wall’s water tight seals. If the concrete cracks, spalls or has exposed rebar, the wall should be patched or repaired. The vegetation along the wall should be maintained within the project easements to ensure visibility and accessibility to the wall. Erosion near the floodwall and floodwall foundation could threaten the stability and should be repaired. The eroded area should be restored to the asbuilt condition and the area protected against future erosion. Lastly, drainage features for the wall should be inspected and properly maintained, including any pipes through the levee and drainage features for the wall itself.
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San Joaquin County, CA Description of Final Alternatives Closure Structures
Overview. Two closure structures would be constructed as part of each of the final alternatives, including the RP. One would be located on Fourteenmile Slough and one would be on Smith Canal. The gates would be open except during routine maintenance, when the Delta exceeds a flood stage of 8 feet NAVD88, or a levee breach has occurred within the slough reach. For reference, the 100-year elevation is 10.1 ft NAVD88 and the 200-year elevation is 12.1 ft NAVD88.
Normal Operation. The gate would be closed when the delta stage is at 8.0 feet NAVD88 and rising and would be opened when the delta stage was 8.0 feet NAVD88 and falling. The gate would also be opened if the stage on the slough side of the gate rose higher than the delta stage. This would allow accumulated interior drainage behind the gate to flow out.
Emergency Operation. One or both gates could be closed indefinitely in case of a levee failure occurred along Smith Canal or Fourteenmile Slough. The gate would be reopened once the levee repairs were made.
Maintenance. Maintenance requirements would include exercising each gate briefly (closed and immediately opened) once or twice a year for O&M purposes. All routine maintenance of the motors, gears, etc. for the gate can be accomplished from above while the gate is in the open position. For major maintenance, the gates can be removed with a barge mounted crane and inspected, repaired and/or replaced.
This would eliminate the need to place stop logs across the opening for routine maintenance.
Frequency and Duration of Operations. An analysis of hypothetical gate operations was conducted for 2010 and 2070 sea level conditions using 32 water years (1983 to 2014) of recorded daily minimum, mean, and maximum tide stages. Delta stages are the result of ocean tide conditions in combination with runoff from the Sacramento and San Joaquin River systems. The historical record is a good indicator of the potential operations because it includes the historical combination of tides and flow. The analysis compared historical stages to the proposed operating criteria and is summarized in Table 4-8.
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San Joaquin County, CA Description of Final Alternatives Table 4-8: Total hours per month gate would have been closed assuming 2010 Sea Level Conditions. 1983 to 2014
Water
Year
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
1983 0 5 8 46 17 59 0 0 0 0 0 0
1984 0 0 11 0 0 0 0 0 0 0 0 0
1985 0 0 0 0 0 0 0 0 0 0 0 0
1986 0 0 0 0 0 2 0 0 0 0 0 0
1987-1994 0 0 0 0 0 0 0 0 0 0 0 0
1995 0 0 0 3 0 11 0 0 0 0 0 0
1996 0 0 0 0 0 0 0 0 0 0 0 0
1997 0 0 1 99 6 0 0 0 0 0 0 0
1998 0 0 0 0 95 0 0 0 0 0 0 0
1999 0 0 0 0 0 0 0 0 0 0 0 0
2000 0 0 0 0 2 0 0 0 0 0 0 0
2001-2002 0 0 0 0 0 0 0 0 0 0 0 0
2003 0 0 2 0 0 0 0 0 0 0 0 0
2004 0 0 0 0 0 0 0 0 0 0 0 0
2005 0 0 0 1 0 0 0 0 0 0 0 0
2006 0 0 7 16 0 0 1 0 0 0 0 0
2007-2010 0 0 0 0 0 0 0 0 0 0 0 0
2011 0 0 0 0 0 1 0 0 0 0 0 0
2012-2014 0 0 0 0 0 0 0 0 0 0 0 0
Maximum 0 5 11 99 95 59 1 0 0 0 0 0
Mean 0 0 1 5 4 2 0 0 0 0 0 0
Minimum 0 0 0 0 0 0 0 0 0 0 0 0
ESTABLISHMENT OF ETL COMPLIANT LEVEES
USACE “GUIDELINES FOR LANDSCAPE PLANTING AND VEGETATION
MANAGEMENT AT LEVEES, FLOODWALLS, EMBANKMENT DAMS AND
APPURTENANT STRUCTURES,” (ETL 1110-2-583)
The USACE “Guidelines for Landscape Planting and Vegetation Management at Levees, Floodwalls, Embankment Dams and Appurtenant Structures,” (ETL 1110-2-583) dated 30 April 2014, provides the standards for vegetation on and adjacent to USACE facilities. To be compliant, levees, floodwalls and 15 feet landward and waterward of the levee toes or floodwall face, must be maintained free of woody vegetation unless a variance is granted by USACE.
Variance
A variance to the ETL may be considered after in-depth engineering analyses have been completed that demonstrate that the levees and/or floodwalls are not imperiled by maintaining woody vegetation on or within 15 feet of the levee or floodwall.
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San Joaquin County, CA Description of Final Alternatives
THE RECOMMENDED PLAN
Structural FRM Features
In order to construct the structural FRM features of the RP, vegetation would need to be removed from the upper half of the levee. This would also be required for construction of the other alternatives. Constructing some features, like slope reshaping or height repairs, will also require removal of all vegetation from the landside levee face and landside easement. Constructing the two closure structures (one each on Fourteenmile Slough and Smith Canal) and the floodwall on Dad’s Point (at Smith Canal) would require removal of waterside vegetation from the waterside levee toe and waterside easement or from the bank.
ETL Compliance
During the construction phase, the levees included in the RP would be brought into compliance with the USACE ETL 1110-2-583, either through removal of vegetation or by obtaining a variance. The levees will undergo intensive engineering evaluation during PED to determine their suitability for a variance. This would be required for any of the alternatives. Based upon the information available at this time and using engineering judgment, it is estimated that 50% of the existing vegetation on the lower waterside slope and within the waterside easement may be allowed to remain; almost none of the vegetation on the landside levee slope or within the landside easement would be allowed to remain.
Variance Evaluation Process
During PED, all levee reaches will be evaluated for a vegetation variance using data that is not currently available in feasibility. This risk-based process involves: determining what species of trees are present in the proposed variance zone; determining the maximum size that trees would grow to; analyzing the root ball size that would be expected for mature trees, which would be used to identify the size of a hole left if the tree falls during a flood event; analyzing the amount of additional scour that could occur in a flood event; seepage and stability analyses accounting for any newly constructed features; and development of cross-sections illustrating the trees, root systems and levee prism. Trees that would likely be identified for removal include dead trees and nut trees. Nut trees may attract burrowing rodents, which may become a levee safety concern.
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San Joaquin County, CA Affected Environment and Environmental Consequences CHAPTER 5 — AFFECTED ENVIRONMENT AND ENVIRONMENTAL
CONSEQUENCES
This chapter describes the affected environment and environmental consequences of each of the alternatives in the final array, mitigation measures for potential impacts, cumulative effects and other environmental considerations for implementing the LSJR project.
NEPA and CEQA require that the environmental effects of a project be analyzed for significance. Under NEPA, impacts are considered significant because of their context (location sensitivity) and intensity (magnitude of impact) (40 Code of Federal Regulations [CFR] Section 1508.27). Under CEQA, impacts are assessed based on specific significance criteria consistent with State CEQA Guidelines Appendix G (14 California Code of Regulations 15000 et seq.). For the purposes of CEQA, potential effects are determined by assessing the potential impacts of the proposed action on the existing conditions for each resource. For the purposes of NEPA, potential project effects are assessed in relation to the conditions described in the No Action Alternative. For this impact analysis, effects are evaluated against existing conditions since these conditions either reasonably represent future conditions in the project area or because existing conditions will facilitate full evaluation and disclosure of the greatest potential impacts of the proposed project.
The CEQA baseline environmental conditions assumed in the preparation of this chapter consist of the existing environment as of January 15, 2010, when USACE published the NOI to prepare an EIS in the Federal Register and SJAFCA published the NOP to prepare an EIR with the State Clearinghouse (State Clearinghouse Number (SCH#) 2010012027). Resource conditions were reassessed and updated between Fall 2013 and Spring 2014. Changes in the existing conditions during that time were not substantial.
The alternatives evaluated in this chapter are described in Chapter 4. They are:
Alternative 1 – No Action
Alternative 7a – North and Central Stockton – Delta Front, Lower Calaveras River and San Joaquin River (SJR) Levee Improvements excluding RD 17
Alternative 7b – North and Central Stockton – Delta Front, Lower Calaveras River and SJR Levee Improvements including RD 17
Alternative 8a – North and Central Stockton – Delta Front, Lower Calaveras River, SJR and Stockton Diverting Canal Levee Improvements excluding RD 17
Alternative 8b – North and Central Stockton – Delta Front, Lower Calaveras River, SJR and Stockton Diverting Canal Levee Improvements including RD 17
Alternative 9a – North and Central Stockton – Delta Front, Lower Calaveras River, SJR Levee Improvements and Mormon Channel Bypass excluding RD 17
Alternative 9b - North and Central Stockton – Delta Front, Lower Calaveras River, SJR Levee Improvements and Mormon Channel Bypass including RD 17
This chapter meets NEPA requirements for determination of the overall impact of each alternative and also CEQA requirements for an impact-by-impact determination of effect. The terms environmental consequences, environmental impacts and environmental effects are synonymous in this analysis.
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San Joaquin County, CA Affected Environment and Environmental Consequences The structure of each section is as follows:
Environmental Setting
Regulatory Framework. This section lists the laws, regulations and policies that are considered in the assessment of effects on the resource and are more fully described in Chapter 7, Compliance with Applicable Laws, Policies and Plans.
Existing Conditions. This section describes the environmental setting and considers environmental conditions in the area at the time that the NOP and NOI were published. Resource conditions were reassessed and updated between Fall 2013 and Spring 2014.
Environmental Consequences
Assessment Methods. This section describes methods, models, process and procedures, data sources and/or assumptions used to conduct the effect analysis. Where possible, effects are evaluated quantitatively. Where quantification is not possible, effects are evaluated qualitatively. Basis of Significance. This section provides the criteria used to define the level at which an effect would be considered significant. Significance criteria (sometimes called thresholds of significance) in this FR/EIS/EIR are based on the checklist presented in Appendix G of the State CEQA Guidelines; factual or scientific information and data; and regulatory standards of Federal, state and local agencies. Under NEPA, preparation of an EIS is triggered if a Federal action has the potential to “significantly affect the quality of the human environment.” The significance thresholds used in this FR/EIS/EIR also encompass factors taken into account under NEPA to evaluate the context and intensity of the effects of an action.
Effects and Mitigation Measures. To comply with NEPA and CEQA, the effects are considered and evaluated as to whether they are direct, indirect or cumulative (40 CFR Section 1508.8). Direct effects are caused by the action and occur at the same time and place. Indirect effects are reasonably foreseeable consequences to the physical environmental that may occur at a later time or at a distance from the project area. Cumulative effects for all resource areas are discussed in Section
5.23, “Cumulative Effects.” Measures to mitigate (i.e., avoid, minimize, rectify, reduce or compensate for) accompany each effect discussion. There are 2 significant differences related to mitigation between NEPA and CEQA:
1) CEQA requires any feasible mitigation measures that could minimize significant impacts be described, while NEPA does not (as long as the agency justifies its decision not to adopt feasible measures); and
2) CEQA mitigation requirements apply only to adverse environmental impacts found to be significant, while NEPA’s regulations apply to any adverse impacts, even if not significant.
Each effect is accompanied by a finding or conclusion, as required. Table 5-1 provides a key for relating the effect findings by relative severity (increasing degree of adversity to the environment).
Table 5-1: Key to Effect Findings (by Increasing Adversity) Beneficial
No Effect
Less Than Significant
Too Speculative for Meaningful Consideration
Significant
Significant and Unavoidable
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San Joaquin County, CA Affected Environment and Environmental Consequences For the purposes of the analyses, the effect findings are defined:
• Beneficial. Would provide benefit to the environment as defined for that resource. • No Effect. Would cause no discernible change in the environment as measured by applicable significance criterion; therefore, no mitigation would be required. • Less Than Significant. Would cause no substantial adverse change in the environment as measured by applicable significance criterion; therefore, no mitigation would be required under CEQA, but there may be mitigation per other environmental regulations. • Significant. Would cause a substantial adverse change in the physical conditions of the environment. Effects based on the significance criteria fall into 2 categories: those for which there is feasible mitigation available that would avoid or reduce the environmental effects to less than significant levels and those for which either there is no feasible mitigation available or for which, even with implementation of feasible mitigation measures, there would remain a significant adverse effect on the environment. Effects that cannot be reduced to a less than significant level by mitigation are identified as significant and unavoidable, as described below. • Significant and Unavoidable. This effect would cause a substantial adverse change in the environment that cannot be avoided or mitigated to a less than significant level if the project is implemented. Even if the effect finding still is considered significant with the application of mitigation, the lead agencies are obligated to consider all feasible measures to reduce the severity of the effect. Under CEQA, a Statement of Overriding Considerations must be adopted if a proposed project results in one or more significant unavoidable impacts. NEPA has no similar "overriding considerations" requirement.
• Too Speculative for Meaningful Consideration. An impact may have a level of significance that is too uncertain to be reasonably determined and would therefore be considered too speculative for meaningful consideration in accordance with State CEQA Guidelines CCR Section 15145. After thorough investigation, the determination of significance may still be considered too speculative to be meaningful. This is an effect for which the degree of significance cannot be determined for specific reasons, such as unpredictability of the occurrence or the severity of the impact, lack of methodology to evaluate the impact or lack of an applicable significance threshold. However, when a determination of significance is uncertain, it is still assumed to be “significant,” as described above.
During the PED phase of the project, if authorized, USACE would then do a site-specific analysis including full biological site surveys and site-specific engineering. USACE shall prepare supplements to either draft or final EISs if: (i) USACE makes substantial changes in the proposed action that are relevant to environmental concerns; or (ii) there are significant new circumstances or information relevant to environmental concerns and bearing on the proposed action or its impacts.
GEOLOGY AND GEOMORPHOLOGY
This section describes the affected environment and environmental consequences relating to geology and geomorphology for the LSJR project. The significance of impacts and mitigation measures to reduce impacts are also discussed.
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San Joaquin County, CA Affected Environment and Environmental Consequences
ENVIRONMENTAL SETTING
Regulatory Framework
Federal
Clean Water Act (CWA) Section 402
State
California Building Standards Code
California Code of Regulations: Title 23, Division 1, Article 8, Sections 111–137 California SMARA of 1975
National Pollutant Discharge Elimination System (NPDES) Permit Regional and Local
City of Lathrop General Plan 1991
City of Stockton General Plan (2007)
San Joaquin County General Plan 2010
City of Manteca General Plan 2023
Existing Conditions
Regional Geology
The project area lies within the San Joaquin Valley portion of the Great Valley Geomorphic Province of California. This geomorphic province is between the north Coast Ranges to the west and the Sierra Nevada to the east and was a depositional basin throughout most of the late Mesozoic and Cenozoic periods. Vast accumulations of sediments deposited during cyclic transgressions and regressions of the shallow sea that once inundated the valley.
As a result, a thick sequence of sedimentary rocks form the bedrock deeply buried in the mid-basin areas of the valley. These rocks are derived from erosion of the adjoining highlands from the Late Jurassic to the Pleistocene periods and from Tertiary volcanic. Late Pleistocene and Holocene (Recent) alluvial deposits cover the area. These consist of reworked fan and stream materials deposited prior to the construction of the existing FRM infrastructure.
The flow of the SJR formed the SJR Valley between the Stockton Arch to the north and the Tehachapi Mountains to the south. The Stockton Arch is a geologic feature (up-warping of crust underneath sediments) underlying the Central Valley in the Delta near Stockton and is considered the subsurface separation between the Sacramento River basin and the SJR basin.
The existing levee system is located on deposits consisting of Holocene alluvium and Holocene basin deposits, as well as late Pleistocene alluvial fan and terrace deposits of the Modesto and Riverbank Formations. These Quaternary deposits are variably dissected and overlain by younger Quaternary (Historical) deposits consisting of channel, floodplain and artificial fill (levees and spoils from dredging).
Local Geomorphology
DWR contracted with URS Corporation to conduct geotechnical and geomorphic evaluations of both urban (Urban Levee Evaluation (ULE)) and non-urban (Non-Urban Levee Evaluation (NULE)) levees in the ATTACHMENT D 1127
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San Joaquin County, CA Affected Environment and Environmental Consequences Sacramento and SJR basins (URS Corporation, 2014). The ULE program included those levees designated as “Urban Project” and “Urban Non-Project” in the project area except for the upper Calaveras River and levees near Brookside and Rough and Ready Island. The NULE program included the “Non-Urban Project” levees on the SJR from the Burns Cutoff south to the Stanislaus River.
The existing geomorphic conditions in the project area include three general geologic domains with relatively consistent geologic deposits. From west to east, these domains are the intertidal, alluvial fan and piedmont. Each domain is divided locally by historic channels, overbank deposits and/or other surface conditions. The intertidal domain (Delta Front) is near present-day sea level and described as consisting of sandy and silty alluvial deposits buried by organic-rich, fine-grained wetland deposits. Subsurface deposits within the intertidal domain are most likely highly variable, laterally as well as vertically. The piedmont domain (foothills) generally consist of relatively old, consolidated and cemented sediments of the middle to late Pleistocene.
The alluvial fan domain (valley floor) comprises most of the project area and generally consists of late Pleistocene deposits (the Modesto Formation) underlain by the Riverbank Formation. Subsurface deposits of sand, silt and clay are most likely highly variable, laterally as well as vertically. Two different geometries were identified within the alluvial fan domain: one in which the levee trends oblique to the mapped abandoned channels (west part of the domain) and the other in which the levee trends parallel to the mapped abandoned channels (east portion of the domain).
The SJR, lower Calaveras River and other streams in the project area are alluvial rivers in which the bed and banks are made up of mobile sediment and/or soil. Alluvial rivers are self-formed, meaning that their channels are shaped by the magnitude and frequency of the floods that they experience and the ability of these floods to erode, deposit and transport sediment. However, construction of levees and placement of bank protection such as riprap in the past have altered these natural processes, including channel migration (river meandering) along these rivers.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Assessment Methods
The types and extent of potential effects and significance were assessed by reviewing geologic and geomorphic maps, reviewing geotechnical and geomorphic studies, discussing geotechnical aspects with professional staff and then considering the work proposed under each alternative.
Basis of Significance
Substantially alter regional geologic resources or processes; Substantially alter local geomorphologic conditions or processes; or Substantially alter natural river meandering, bank erosion and deposition.
ALTERNATIVE 1 - NO ACTION
Under the No Action Alternative, no construction activities would occur and the geologic resources and processes would be expected to remain the same because of the regional nature and extent of the resource.
While regional geomorphologic conditions and processes would also remain the same, the local geomorphic conditions on the alluvial fan would be influenced by past FRM and future development. Construction of levees, berms and bridges is assumed to continue to affect the patterns of sediment erosion and deposition on the valley floor fan. Changes in erosion and/or deposition could affect the structure and functioning of existing levees, leading to increased risk of levee failure and flooding.
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San Joaquin County, CA Affected Environment and Environmental Consequences The magnitude of the impact of flooding resulting from levee failure would depend on the location of the levee breach, severity of the storm and river flows at the time of flooding. In the event of a flood, levee failures could result in soil scouring and erosion in localized areas within several hundred feet of a levee breach, altering local geomorphologic processes. The location and extent of damage and impacts related to soil erosion could be minor to extensive. Predicting these events and providing a determination of significance is not possible based on the information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
ALTERNATIVES 7A, 7B, 8A, 8B, 9A AND 9B
These alternatives would have no effect on the geology or regional geologic resources or processes, because of the nature of the proposed levee work and the regional extent of the resources. The work would be limited to borrow site activities and improvements along levees within a relatively small project area as compared with the geologic and regional geomorphologic conditions in the broader San Joaquin Valley and adjacent foothills.
However, the alternatives could have short and long-term effects on the local geomorphology in the project area. Short-term effects during construction involving the bank and/or water side of the levees (Chapter 4, Description of Final Alternatives) would result in substantial soil disturbance and could include temporary disruptions in patterns of bank erosion and downstream deposits of sediments on the valley floor caused by wind or early-season rainfall events. The disruption may increase depending on the extent, type, and amount of work proposed under each alternative; e.g., 7a would result in the least disruption while 9b would result in the most disruption.
The construction contractor shall be required to prepare and implement a Stormwater Pollution Prevention Plan (SWPPP) and comply with the conditions of the NPDES general stormwater construction activity permit. Potential erosion during construction would be addressed through the implementation of BMPs.
Potential erosion concerns and the associated BMPs are addressed in Water Quality, Section 5.5. In addition, Alternatives 9a and 9b, would result in the introduction of floodflows to Old Mormon Slough that could routinely mobilize some sediment and transport it downstream into the Stockton Deepwater Ship Channel. The flood bypass would be designed to minimize these erosion and deposition processes to lessthan-significant levels.
Consistent with project objectives, the completed project would provide long-term FRM benefits by improving the structure and functioning of the existing levee system. As such, the levees would continue to affect local geomorphologic processes similar to those under the No Action Alternative. As a result, there would be no significant long-term effects on geology or geomorphology and the project would result in less than significant impacts. Additionally, the completed project would not further alter the natural river meandering or deposition and is designed to prevent bank erosion; therefore, would result in less than significant impacts.
MITIGATION
There would be no significant effects on geology or geomorphology; therefore, no mitigation is required.
SEISMICITY
This section describes the affected environment and environmental consequences relating to seismicity for the LSJR project as well as the significance of the impacts and mitigation measures to reduce impacts.
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San Joaquin County, CA Affected Environment and Environmental Consequences
ENVIRONMENTAL SETTING
Regulatory Framework
Federal
Federal Earthquake Hazards Reduction Act
State
Alquist‐Priolo Earthquake Fault Zoning Act
California Building Standards Code
California Code of Regulations: Title 23, Division 1, Article 8, Sections 111–137 California Seismic Hazards Mapping Act
Regional and Local
City of Lathrop General Plan 1991
City of Stockton General Plan 2007
San Joaquin County General Plan 2010
City of Manteca General Plan 2023
Existing Conditions
Faults and Seismic Activity
The west side of the Central Valley is a seismically active region. Many faults exist in the San Francisco Bay Area and numerous earthquakes of magnitude (M) 5.0 or greater have occurred on regional faults, primarily those of the San Andreas Fault system. Significant earthquakes are generally associated with crustal movements along well-defined active fault zones. The last major earthquake on the San Andreas Fault was the Loma Prieta earthquake in October 1989 with a magnitude of 6.9, approximately 71.2 miles from Stockton. Other large earthquakes that have occurred within the region were the Milpitas earthquake (5.6 M) in October 2007 on the Calaveras Fault, 44.2 miles from Stockton and the American Canyon earthquake (6.0 M) in August 2014 on the West Napa Fault, 58.2 miles from Stockton.
No active faults have been mapped within project area by the USGS or California Geological Survey (Jennings, 1994) and the project area is not located in an Alquist-Priolo Earthquake Fault Zone (California Geological Survey, 2007). The Stockton Fault (or Stockton Arch) traverses in a northeast to southwest direction, parallel to Highway 4, North of RD 17. However, the Stockton Fault has not been active in the last 1.6 million years. The Vernalis, San Joaquin and Black Butte Faults are located near Tracy, CA, 2.5 miles, 11 miles and 12.5 miles west of the project area, respectively. However, these faults have not been active in the last 11,000 to 1.6 million years. As a result, ground rupture in the project area is of a low risk as compared to other areas in the San Joaquin Valley.
The U.S. Geological Survey (2005) estimated the probabilities of a magnitude 6.7 or greater earthquake occurring at the faults located in the study vicinity before 2032: Hayward Fault (27 percent), San Andreas Fault (21 percent), Greenville Fault (3 percent) and Concord-Green Valley Fault (4 percent). Moreover, using newly collected and updated theories of earthquake activity, the USGS concluded that there is a 62 percent chance of at least one magnitude 6.7 or greater quake striking somewhere in the San Francisco Bay region before 2032 (USGS, 2005).
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San Joaquin County, CA Affected Environment and Environmental Consequences Potential seismic hazards from a nearby moderate to major earthquake are generally classified as primary and secondary. The primary effect is fault ground rupture, also called surface faulting. Because there are no active faults in the project area and the area is not located within an Alquist-Priolo Earthquake Fault Zone, fault ground rupture is negligible. Common secondary seismic hazards include ground shaking, liquefaction, subsidence and seiches.
Active faults were mapped and are classified as A, B or C type faults specifically for use with the California Building Standards Code. Faults are classified based on the magnitude of earthquakes typically associated with them and the fault’s slip rate. Type A faults cause the greatest potential destruction; Type C cause the least. Faults in the vicinity of the project area with a moderate to high potential for seismicity include the Hayward, Calaveras, Concord-Green Valley and Greenville Faults. The closest known active faults to the project and the details and project risks associated with them, are listed in Table 5-2.
Table 5-2 Maximum Credible Earthquake Magnitudes
Fault
Estimated
Distance from
Project Site Fault Class1
Maximum
Credible
Earthquake2
Slip Rate
(mm/yr)
Greenville Fault Zone, North
Section 20 miles B 6.6 2
Greenville Fault Zone, South
Section 24 miles B 6.6 2
Calaveras Fault – Northern
Segment 34 miles B 6.8 6
Concord- Green Valley 38 miles B 6.2 5
Hayward Fault – North
Segment
45 miles A 6.4 9
Notes:
1. Faults with an “A” classification are capable of producing large magnitude (M) events (M greater than
7.0), have a high rate of seismic activity (e.g., slip rates greater than 5 millimeters per year) and have wellconstrained paleoseismic data (e.g., evidence of displacement within the last 700,000 years). Class B faults are those that lack paleoseismic data necessary to constrain the recurrence intervals of large-scale events.
Faults with a “B” classification are capable of producing an event of M 6.5 or greater.
2. The moment magnitude scale is used by seismologists to compare the energy released by earthquakes.
Unlike other magnitude scales, it does not saturate at the upper end, meaning that there is no particular value beyond which all earthquakes have about the same magnitude, which makes it a particularly valuable tool for assessing large earthquakes.
Sources: Cao et al., 2003; Jennings 1994; Petersen et al., 1996; data compiled by USACE in 2014 Liquefaction and Settlement
Liquefaction is the liquefying of certain sediments during seismic ground-shaking, resulting in temporary loss of support to overlying sediments and structures. Differential settlement occurs when the layers that liquefy are not of uniform thickness, a common problem when the liquefaction occurs in artificial fills.
Poorly consolidated, water-saturated fine sands, located within 30 to 50 feet of the surface, typically are considered the most susceptible to liquefaction. Dry soils and sediments consisting of finer grained materials are generally not susceptible to liquefaction.
Many of the levees in the project area are constructed over alluvial deposits and may be susceptible to liquefaction or degradation due to a seismic event. The area is unusual in that it contains infrequently waterATTACHMENT D 1131 Lower San Joaquin River
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San Joaquin County, CA Affected Environment and Environmental Consequences saturated levees in Central and South Stockton, but also frequently saturated levees in North Stockton and Delta Front. Frequently saturated levees are likely to be sensitive to seepage, leading to breach with seismicevent induced transverse cracking or displacement.
USACE conducted liquefaction triggering analyses and identified liquefiable material along several levees in the project area. Static limit equilibrium stability analyses were then conducted for these levees. Based on the analyses, the flood protection ability after a 200-year seismic event was judged to be compromised at several locations. Thus, a large regional earthquake during a major flood event would increase the potential liquefaction, settlement and levee failure. The greatest susceptibility is along the Delta Front and North Stockton. The highest combination of susceptibility and consequences occurs along a one mile stretch of the San Joaquin River immediately downstream of the Calaveras River. This portion of levee experiences about 5 feet of water above the landside levee toe on a daily basis at high tide.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Assessment Methods
The types and extent of potential effects and significance were assessed by reviewing seismic fault and event maps, reviewing seismic studies, discussing seismic aspects with professional staff and then considering the work proposed under each alternative.
Basis of Significance
• Expose people or structures to potential substantial adverse effects, including the risk of loss, injury or death involving:
o Rupture of a known earthquake fault as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault; strong seismic ground shaking; o Seismic-related ground failure, including liquefaction; or o Landslides.
Be located on a geologic unit or soil that is unstable or that would become unstable as a result of the project and potentially result in an on-site or off-site landslide, lateral spreading, subsidence, liquefaction or collapse.
The project area is not located within or adjacent to an Alquist-Priolo Fault Zone or any known active fault.
Therefore, the risk of surface fault rupture is negligible and is not evaluated further. Additionally, the project area is relatively flat and there would be no adverse impacts related to landslides. So, landslides are not addressed further.
ALTERNATIVE 1 - NO ACTION
Under the No Action Alternative, no construction activities would occur. The structural integrity of existing levees, berms and bridges would continue to pose a risk for flood damage to the Stockton, Lathrop and Manteca areas from high magnitude seismic events on active faults to the west. Some of the levees in tidally loaded areas would also continue to be at risk from seismically induced structural instability and/or failure due to liquefaction of soils. The magnitude of the impact of flooding resulting from levee failure would depend on the location of the levee breach, severity of the storm and river flows at the time of flooding.
One location on the San Joaquin River is at risk of liquefaction, levee failure, and flooding under normal tidal loading. Predicting other events which combine seismic and flood loading and providing a ATTACHMENT D 1132
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San Joaquin County, CA Affected Environment and Environmental Consequences determination of significance is not possible based on information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
ALTERNATIVES 7A, 7B, 8A, 8B, 9A AND 9B
These alternatives would have no effects on known seismic faults or cause ground movement along faults, because work would be limited to borrow sites activities and improvements along surface waterways, while seismic forces are subsurface and regional. In addition, there are no identified active faults in the project area.
The proposed project could experience at least one earthquake within the life of the project. Design, construction and maintenance must comply with the regulatory standards of USACE including requirements for seismic design. The design and construction of the cutoff walls, floodwalls and/or levees would meet or exceed applicable design standards for static and dynamic stability, seismic ground shaking, liquefaction, subsidence and seepage, minimizing the potential for significant damage. Therefore, the proposed project would not affect the existing geology and seismicity of the area or expose people or structures to potential risk or injury.
Consistent with project objectives, the completed project would provide long-term FRM benefits by improving the structure and functioning of the existing levee system. This includes designing the proposed features to avoid or minimize any potential for seismic-related ground failure in tidally influenced areas of the project.
The geotechnical investigation prepared for the proposed project did not indicate evidence of instability because of landslides, subsidence or collapse. Liquefaction analysis indicates some existing levees within the project area are constructed over alluvial deposits that could be susceptible to liquefaction or degradation due to a seismic event. Design recommendations to address this condition are provided in the Geotechnical Investigation would be implemented. The proposed project would implement standard grading and soil engineering practices to ensure that foundations are adequately supported and do not settle or otherwise fail. This includes excavating the existing soils and replacing them with compacted engineered fill. In addition, all structures associated with the proposed project would be designed in accordance with USACE standards. Because project facilities would be designed, constructed and maintained in accordance with applicable standards, risk of failure due to a seismic event would be minimized and this impact is less than significant.
MITIGATION
There would be no significant effects from seismicity; therefore, no mitigation is required.
SOILS AND MINERAL RESOURCES
This section describes the affected environment and environmental consequences relating to soils and mineral resources for the LSJR project. The significance of the impacts and mitigation measures to reduce impacts are also discussed.
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San Joaquin County, CA Affected Environment and Environmental Consequences
ENVIRONMENTAL SETTING
Regulatory Framework
Federal
CWA Section 402
State
California Building Standards Code
California Code of Regulations: Title 23, Division 1, Article 8, Sections 111–137 California Surface Mining and Reclamation Act of 1975 NPDES Permit
Regional and Local
City of Lathrop General Plan 1991
City of Stockton General Plan 2007
San Joaquin County General Plan 2010
City of Manteca General Plan 2023
Existing Conditions
Soil Types and Characteristics
Soils in the San Joaquin Valley resulted from erosion and deposition of rock types in and along the SJR and tributaries in the watershed. According to a NRCS soil survey of San Joaquin County, three general soil map units (Qm, QdB, Qs) are found within the 100-year floodplain of the SJR (NRCS, 2002). General soil map units describe a unique natural landscape generally comprised of 2 or more soil series. A soil series describes soils that have nearly identical profiles and other physical properties.
Soils in the project area range from highly sandy to dominantly fine, with fine to extremely coarse gradations. Erosion and expansion potentials are low to moderate for the soil series. Severe erosion is not generally a concern due to the relatively level terrain; however, wind can erode exposed and recently disturbed soils. Expansive soils contain a higher content of clay and expand and shrink, depending on water content. Subsidence can occur locally as a result of seasonal changes in soil moisture content. Substantial groundwater-related subsidence occurred throughout the San Joaquin Valley as drainage of lowlands resulted in the decomposition of organic components in the soils.
Mineral Resources
In compliance with SMARA, the California Geological Survey established the classification system to denote the location and significance of key extractive resources. Sand and gravel aggregate are the principal mineral resources in San Joaquin County. According to the California Department of Conservation (CDC), Division of Mines and Geology (1988), the majority of the project area is classified as MRZ-1, meaning that no significant mineral deposits are present in this area or that little likelihood exists for their presence.
An area between Lathrop and Manteca (Stockton-Lodi Production-Construction Region, Segment D) is classified as MRZ-2, meaning that significant mineral deposits are known to be present or are highly likely to be present and is designated as being of regional significance. The south part of RD 17, in and around ATTACHMENT D 1134
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San Joaquin County, CA Affected Environment and Environmental Consequences the Cities of Lathrop and Manteca, is classified as MRZ-3, meaning that there is a potential for mineral resources in this area. Just north of Stockton is another small area delineated as MRZ-3.
Lands classified as MRZ-1 or MRZ-3 are not affected by State policies pertaining to the maintenance of access to regionally significant mineral deposits under the California Surface Mining and Reclamation Act of 1975. Lands classified as MRZ-2 are subject to these State policies that support mining operations, including dredging and quarrying and are intended to ensure that mineral resources will be available when their development is necessary or economically feasible (CDC, 2013). However, the MRZ-2 sector between Lathrop and Manteca lies outside the area that would be affected by the alternatives in the LSJRFS.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Basis of Significance
Result in substantial erosion of soil or loss of topsoil; Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994), creating substantial risks to life or property;
Have soils incapable of adequately supporting the use of septic tanks or alternative wastewater disposal systems where sewers are not available for the disposal of wastewater; or Result in the loss of availability of a known mineral resource of economic value to the region and the residents of the State or a locally important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan.
The project would not involve the use of wastewater disposal systems of any kind, including septic systems and there would be no impacts. Therefore, this issue is not addressed further in this document.
ALTERNATIVE 1 - NO ACTION
Under the No Action Alternative, no construction activities would occur. The soil types and their characteristics on the alluvial fan in San Joaquin County would be expected to remain the same as deposited over time. Water and wind erosion of exposed and recently disturbed soils would continue to weaken the structure of levees along the SJR and tributaries. The risk of levee failure and flooding would also continue, resulting in soil scouring and substantial loss of nearby valuable topsoil in the event of a breach. The eroded soils could be carried by the floodwaters and deposited in developed areas, causing damage to residences, businesses and infrastructure. This would be considered a potentially significant effect. Implementation of USACE levee vegetation management requirements is not expected to occur under the No Action Alternative; therefore, removal of waterside and landside vegetation would not occur.
The magnitude of impacts and flood damage related to soil erosion would depend on the levee breach location, storm severity, flooding duration and river flows. During a flood, levee failures could result in soil scouring, erosion and permanent loss of top soil in localized areas within several hundred feet of a levee breach. Predicting these events and providing a determination of significance is not possible based on the information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
The principal mineral resources in San Joaquin County are deposits of sand and gravel aggregate and many companies are currently mining and processing these deposits as regulated by the State and County. Mining operations would continue to be at risk of disruption, damage or loss of mineral resources in the event of levee failure and flooding, which could affect the local economy. The substantial soil subsidence in the valley south of Stockton due to over-pumping of groundwater and drainage of lowlands by agricultural and municipal interests would also continue. These would be considered as potentially significant effects.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVES 7A, 7B, 8A, 8B, 9A AND 9B
These alternatives would have no effect on the soil types or their characteristics on the alluvial fan.
However, they would have short-term effects on soils in the project area during construction. These would include disturbing soils at staging areas; clearing, excavating and clearing soils during site preparation; excavating, stockpiling and/or removing soil material at borrow sites; and depositing and shaping soils at the work site. Table 5-3 lists the approximate area of disturbance by alternative. These activities could result in the potential for surface water to carry sediment into the stormwater and local waterways or increase airborne dust, resulting in potential effects on existing water quality and air quality. These short-term effects would increase with the extent, type and amount of work proposed under the alternatives. The potential effects on water quality and air quality of the alternatives, BMPs and mitigation measures are discussed in detail under Sections 5.5 and 5.8, respectively.
Table 5-3: Approximate Area of Disturbance by Alternative Alternative
Construction
Footprint (ac)
Estimated Borrow
Area (ac) Total Footprint (ac)
Alternative 7a 158 138 296
Alternative 7b 367 394 761
Alternative 8a 219 266 485
Alternative 8b 428 450 878
Alternative 9a 190 138 328
Alternative 9b 402 394 796
Under the NPDES permitting program, the preparation and implementation of a SWPPP is required for construction activities that disturb more than 1 acre in size and must identify potential sources of erosion that may be reasonably expected to affect the quality of stormwater discharges, as well as identify and implement BMPs that ensure the reduction of eroded soil during stormwater discharges. The contractor would be responsible for implementing BMPs and ensuring compliance with the requirements of the SWPPP. With erosion control BMPs, SWPPP and USACE oversight in place, impacts related to accelerated erosion during construction and ground-disturbing maintenance are expected to be less than significant and no mitigation is required.
The ground-disturbing activities associated with vegetation clearing to meet USACE vegetation management guidance would require vegetation be cleared on levee slopes and 15 feet out from the waterside and landside levee toes, potentially resulting in significant erosion and sedimentation. Although the area subject to disturbance is substantial, significant large-scale erosion and generation of runoff is not anticipated because construction would be reduced or not occur during the winter months because of risks to levees during the flood season. Site specific measures that would control erosion would be described in more detail in the SWPPP, which is a requirement of the NPDES General Permit (Section 5.5 WATER QUALITY). The specific BMPs to be implemented would be determined prior to issuance of the NPDES General Permit, in coordination with the RWQCB and would substantially reduce or prevent erosion and sediment-related effects. So, this impact is considered less than significant and no mitigation is required.
Once construction is complete, all disturbed areas would be reseeded to encourage revegetation and minimize erosion. As a result, the short-term effects on local soils would likely be less than significant.
Once the project is complete, the type and frequency of maintenance activities would be expected to remain the same. As a result, the project would not be expected to have long-term effects on soils.
Soils in the project area have not been identified as compressible or unstable. Their expansion potential is not known at this time. However, construction of all project elements would be supported by a site-specific geotechnical investigation, which would include an evaluation of site soils and recommendations to ensure ATTACHMENT D 1136
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San Joaquin County, CA Affected Environment and Environmental Consequences project elements are appropriately designed and constructed, consistent with the current California Building Code earthwork standards and USACE and CVFPB standards. With adherence to these standards and any additional recommendations of the site-specific geotechnical investigation, impacts associated with potential adverse soils conditions would be less than significant. No mitigation is required.
These alternatives would have no short-term or long-term effects on the acquisition, mining or processing of the mineral resources in the project area. None of the existing sand and gravel mining or processing operations are located at the work sites. Implementation of the project would not reduce or eliminate availability of mineral resources. However, the completed project would provide long-term FRM benefits by reducing the potential for loss of soils or mineral resources due to erosion and levee failure. The potential loss of locally or regionally significant mineral resources would be a less than significant impact. No mitigation would be required.
To identify potential locations for borrow material, soil maps and land use maps were obtained for a 25- mile radius surrounding the project area. Whenever possible, borrow sites would be obtained from willing sellers and located on land to minimize effects on the environment. Once details of borrow locations are finalized, coordination with the CDC SMGB would occur to ensure compliance with SMARA , including any additional permitting CEQA (as determined by the SMARA lead agency SMGB) or NEPA required prior to commencing surface mining at the borrow sites. After material is extracted, borrow sites would be returned to their existing use whenever possible.
MITIGATION
There would be no significant effects on soils and mineral resources, therefore no mitigation is required.
HYDROLOGY AND HYDRAULICS
This section describes the affected environment and environmental consequences relating to hydrology and hydraulics for the LSJR project. The significance of the impacts and mitigation measures to reduce impacts are also discussed.
Regulatory Framework
Federal
CWA of 1972, 33 U.S.C §1251, et seq.
FEMA National Flood Insurance Program, 44 CFR
Safe Drinking Water Act of 1974, 42 U.S.C. §300f-300j-9) Rivers and Harbors Act of 1899, 33 U.S.C. §401, et seq.
State
California Department of Water Resources Urban Levee Design Criteria Central Valley Flood Protection Plan
Porter-Cologne Water Quality Control Act of 1970, California Water Code Sections 13000-16104
ENVIRONMENTAL SETTING
Existing Conditions
The LSJRFS study area includes 64 square miles of urban and agricultural lands subject to comingled flooding from multiple sources. Based on 2010 census data and floodplain mapping presented herein, ATTACHMENT D 1137
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San Joaquin County, CA Affected Environment and Environmental Consequences 235,000 people reside within the study area’s 0.2 percent (1/500) ACE Floodplain and are susceptible to being inundated by the primary sources of flooding identified in this study.
Precipitation in the project region occurs primarily during the months of November through March with normal annual precipitation ranging from about 13 inches near Tracy to 19 inches near Lodi (WRCC, 2014).
At Stockton, the normal annual precipitation is 14 inches (WRCC, 2014). Winter storms are associated with frontal systems from the Pacific Ocean moving against the Sierra Nevada. As the moist air rises over the mountain range, it loses its ability to retain moisture, resulting in intense precipitation. The resulting floods are usually characterized by high peak flows of short duration, but when antecedent rainfall results in saturated ground conditions or when the ground is frozen, the volume of runoff is much greater and flooding is more severe. Thunderstorms lasting up to three hours can occur over small areas at higher elevations from late Spring through early Fall. Within the smaller catchments, thunderstorms can result in runoff with high peak flows of short duration and low volumes.
The study area is susceptible to flooding from the combination of 6 principal sources including the Delta, SJR, Calaveras River and Mormon Slough system, Bear Creek, French Camp Slough system and Mosher Slough. The main contributing drainage areas to the study area include the Sacramento River (25,200 square miles), SJR (13,500 square miles) and the Mokelumne River (1,200 square miles). Runoff within the study area is highly influenced by reservoir regulation. Interior drainage is not considered a principal source of flooding. The following describes the flood sources within the study area.
Sacramento-San Joaquin Delta
The Delta covers more than 1,000 square miles of Central California. A map of the Delta is provided as Figure 5-1. The Delta is located at the confluence of the Sacramento and SJRs at the head of Suisun Bay, the most easterly extending arm of the San Francisco Bay system. In general, the Delta extends from about Sacramento on the north, to Stockton on the south and near Pittsburg on the west. This region, which is very flat, was reclaimed from a natural tidal area by hundreds of miles of levees along natural and manmade waterways that divide it into 100 tracts locally known as "islands." ATTACHMENT D 1138
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-1: The Delta
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San Joaquin County, CA Affected Environment and Environmental Consequences Before the islands were reclaimed, much of the Delta was covered by water from the daily tide cycle. During times of high runoff from the Sacramento and SJR Basins, much of the Delta would be flooded.
Reclamation of many of the Delta islands subjected the peat soils to oxidation. As a result, the interiors of most islands have subsided well below sea level. Elevations within the islands now range from just above mean sea level to 10 feet below mean sea level.
Maximum stages within the Delta result from runoff from storms of different origins that do not have the same annual exceedance frequency at all locations and from tides of varying magnitudes that seldom reach their maximum stages concurrently with the peak flows. In some years, the annual maximum stage at all locations occurs during the same storm event. However, in other years, the peak stages in the northern part of the Delta occur during a different time period than those in the southern part of the Delta and vice versa.
The differences are caused by the geographical distribution of the contributing drainage basin, antecedent conditions such as snowpack and soil moisture and the fluctuation of the storm tracks over California. If the flood runoff is from the Sacramento River basin, the stages will be higher in the northern part of the Delta. If the flood runoff is from the SJR, then the stages will be higher in the southern part of the Delta.
The Delta Front reaches of the study area are susceptible to flooding from Fivemile Slough, Fourteenmile Slough and Tenmile Slough. These sloughs have relatively small tributary areas; however, the levees along these sloughs provide flood risk reduction from the large volume of water in the Delta. If a breach were to occur in a Delta Front levee, the floodwaters would likely equalize with the high stage of the Delta due to the enormous volume of water held in the sloughs and river channels.
San Joaquin River (SJR)
The SJR is the principal stream in the southern half of the Central Valley. It is a perennial stream sustained through the summer by melting snow and releases from reservoirs. Its main headwater tributaries, the south and middle forks, rise in glacial lakes in the southern Sierra Nevada. They join at an elevation of 3,600 feet NAVD88 to form the main stem, which flows west-southwesterly to the valley floor. The main stem then flows northwesterly down the main trough of the valley to the study area and its terminus at Suisun Bay.
Upstream from the study area, the river is joined by several major tributaries flowing from the Sierra Nevada Mountain Range. There are also a number of minor low elevation tributaries that flow from the east and west and have little effect on flood flows and stages.
The major tributaries flowing from the east are the Stanislaus, Tuolumne, Merced, Chowchilla and Fresno Rivers. Less significant eastside tributaries comprise the Calaveras River, Bear Creek and French Camp Slough (terminus of Duck and Littlejohns Creeks systems). The principal Westside tributaries are Panoche, Los Banos, San Luis and Orestimba Creeks. Fresno Slough, a distributary of the Kings River that cuts through the valley-floor barrier ridge separating the Tulare Lake Basin from the SJR Basin proper, could contribute runoff to the SJR during extreme flood events. Reaches of the SJR within the study area are described below.
Stanislaus River to Paradise Cut. The confluence of the San Joaquin and Stanislaus Rivers defines the upstream extent of the hydraulic model used for this study. The USGS SJR at Newman stream gage is located at the upstream end of this reach, 2 miles downstream of the Stanislaus River. Within this reach, the SJR has a meandering plan form consisting of oxbows and cutoffs. The main channel varies in width from 300 to 600 feet. The floodway is contained by left and right bank levees that are 10 to 15 feet tall. The floodway between the levees varies in width from 900 feet to 4000 feet. The distance between the waterside levee toe and channel bank ranges from 0 feet to over 2000 feet. Flood stages within this reach are dominated by runoff from the SJR.
Paradise Cut to Old River. Paradise cut defines the upstream extent of this reach. Paradise cut is a distributary from the SJR that conveys floodwaters west into the Delta. The flow split is managed by ATTACHMENT D 1140
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San Joaquin County, CA Affected Environment and Environmental Consequences Paradise Dam, which is a 230 foot long rock weir along the left bank of the SJR. The flow split is defined by the hydraulic characteristics of the dam and a meander cutoff levee located on the SJR downstream of the dam. The meander cutoff levee extends west from the right bank levee and impinges on the SJR downstream of Paradise Cut.
Within this reach, the SJR transitions to a less sinuous plan form. The main channel varies in width from 300 to 600 feet. The floodway is contained by left and right bank levees that are 10 to 15 feet tall. At the upstream end of the reach, the floodway width between the levees varies from 900 feet to 4,000 feet and the distance between the waterside levee toe and channel bank ranges from 0 feet to over 2,000 feet. At the downstream end of the reach, the floodway width narrows to approximately 500 feet. However, there is 1 oxbow reach where the floodway is 2,000 feet wide. Flood stages within this reach are dominated by runoff from the SJR.
One mile downstream of Paradise Cut on the right bank is Wetherbee Lake and the upstream tieback levee of RD 17. The Wetherbee Lake levee segment along the SJR was a feature of the San Joaquin Flood Control Project, which cut off Walthall slough from the SJR to reduce damages to a resort development along the river. The RD 17 tieback levee is located downstream of Walthall Slough and extends east along the right bank to high ground. The RD 17 tieback levee is higher than the right bank levee of the SJR and diverts any floodwaters back into the SJR. This situation occurred in the flood of January 1997 and is shown on Figure 5-2. Flood stages within this channel reach are dominated by runoff from the SJR. Flood stages in the right overbank are dominated by runoff from the SJR and Stanislaus River.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-2: 1997 Flood Wetherbee Lake and RD17 Tieback Levee ATTACHMENT D 1142
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San Joaquin County, CA Affected Environment and Environmental Consequences Old River to French Camp Slough. Old River is a distributary from the SJR and conveys floodwaters west into the Delta. There is no hydraulic structure to manage the flow split, which is defined by the hydraulic characteristics of Old River and the SJR downstream of the flow split.
Within this reach, the SJR further transitions to a less sinuous plan form. The main channel varies in width from 200 to 300 feet. The floodway is contained by left and right bank levees that are 10 to 15 feet tall.
From Old River to 4 miles downstream, the right bank levee is 3 feet taller than the left bank. The floodway width between the levees varies from 300 feet to 400 feet and widens to 1,400 feet at a few meander bends.
The waterside levee face forms the channel bank along most of this reach. Flood stages within this reach are dominated by runoff from the SJR.
French Camp Slough to Burns Cutoff. French Camp Slough is a tributary to the SJR. The main channel varies in width from 200 to 300 feet. The floodway is contained by left and right bank levees that are 10 to 15 feet tall with a variable width between the levees of 300 feet to 400 feet. The waterside levee face is next to the channel bank along most of this reach. Flood stages are dominated by runoff from the SJR, but influence of ocean tides is evident in flood stage hydrographs.
Burns Cutoff to Deep Water Ship Channel. Burns Cutoff is a secondary channel of the SJR that conveys water on the west side of Rough and Ready Island. Burns Cutoff flows back to the SJR/Stockton Deep Water Ship Channel just downstream of the Calaveras River. The SJR main channel is 300 feet wide in this reach. The floodway is contained by left and right bank levees that are 10 to 15 feet tall. The right bank levee height tapers to high ground at the downstream end of the reach where it meets the San Joaquin Deep Water Ship Channel. The floodway width between the levees varies from 300 feet to 400 feet. The waterside levee face is next to the channel bank along most of this reach. Flood stages are dominated by runoff from the SJR. However, influence of ocean tides is evident in flood stage hydrographs.
Deep Water Ship Channel to Calaveras River. Within this reach, the SJR is maintained as a navigation channel through periodic dredging to a minimum draft of 35 feet below mean low water. The channel is 600 feet wide and is contained by high ground on either side. Smith Canal is located along the right bank of this reach, 1 mile downstream of the turning basin. The Calaveras River, a tributary to the SJR is near the downstream end of this reach. Flood stages within this reach are dominated by runoff from the Sacramento and SJRs in combination with ocean tides. Inflows from the Calaveras River and Smith Canal have a negligible influence because flood flows are not coincident with the SJR. In addition, the SJR has a relatively large cross sectional area due to channel dredging.
Calaveras River and Mormon Slough
The Calaveras River is a tributary of the SJR. Elevations in the drainage vary from 6,000 feet in the highest headwater areas to 30 feet in the lower part of the study area. A map of the watershed is provided in Figure 5-3. In the study area, the Calaveras River is distributary in nature. The stream divides into the north and south branches at Bellota, where a diversion structure was constructed as part of the Federal Mormon Slough Project. The northern branch Calaveras River flows westerly across the valley floor to join the SJR just west of Stockton. Very little flow enters this branch except during the summer when diversions are made for irrigation and ground-water replenishment. The southern branch, Mormon Slough, carries most of the flow. Its course extends in a general southwesterly direction from Bellota to the Stockton Diverting Canal flow diversion structure. The structure diverts all flood flows to the diverting canal, which discharges into the Calaveras River. The Mormon Slough reach below the diverting dam is referred to Old Mormon Slough. The source of flow in Old Mormon Slough is the local tributary area downstream of the diversion structure.
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San Joaquin County, CA Affected Environment and Environmental Consequences Bear Creek
Bear Creek is a tributary to Disappointment Slough of the Delta (Figure 5-4). At its confluence with Disappointment Slough, Bear Creek has a drainage area of 115 square miles. The watershed drains the western slopes of the Sierra Nevada foothills and has a maximum elevation of 1,000 feet NAVD88. The watershed is below the average snowline elevation. Based on preliminary hydrologic and hydraulic model analysis, Bear Creek was not found to be a source of flood risk to the study area. So, the results of the detailed hydraulic analysis for Bear Creek are not provided in this report.
Mosher Slough
Mosher Slough is a small tributary to Bear Creek, which discharges to Disappointment Slough of the Delta (Figure 5-6). The majority of the watershed is located in the urbanized area of Stockton between Interstate 5 and Highway 99 with the watershed area totaling 16 square miles (SJAFCA, 2012). The watershed’s terrain has moderate slopes and reaches a maximum elevation of 65 feet NAVD88.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-3: Calaveras River Watershed Boundary
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-4: Bear Creek Watershed Boundary
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San Joaquin County, CA Affected Environment and Environmental Consequences French Camp Slough
French Camp Slough is a tributary to the SJR south of Stockton. The slough receives waters from Duck Creek and LittleJohn Creek (Figure 5-5). At its confluence with the SJR, French Camp slough has a drainage area of 430 square miles. The watershed drains the western slopes of the Sierra Nevada foothills and has a maximum elevation of 2,100 feet NAVD88. The watershed is significantly below the average snowline elevation. This slough, with or without upstream reservoirs, has no effect on major flood flows in the SJR (USACE, 1955).
Duck Creek
Duck Creek is a small tributary of the French Camp Slough south of Stockton, lying between the Calaveras River-Mormon Slough system and LittleJohn Creek. It has a total drainage area of 54 square miles (Figure 5-5). Reduction of flood flow in the stream is accomplished by the Farmington Reservoir Project, which prevents overflow of LittleJohn Creek floodwater into Duck Creek and the Duck Creek Diversion, which diverts floodwater from upper Duck Creek into the improved channel of LittleJohn Creek. Half of the Duck Creek drainage area lies above the Duck Creek Diversion Dam. The upstream area, about 28 square miles of typical foothills, lies below 500 feet in elevation with an overall streambed slope of 20 feet per mile.
Downstream of the diversion structure, the gently sloping valley floor is a poorly defined tributary drainage area. This creek has no effect on major flood flows in the SJR.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-5: French Camp Slough Watershed Boundary
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-6: Mosher Slough Watershed Boundary
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San Joaquin County, CA Affected Environment and Environmental Consequences Flood Frequency and Floodplains
As described in Section 2.1.1, the study area has little topographic relief, which results in the potential for expansive flooding. The existing levee system in the project area reduces flood risk to over 71,000 acres of mixed-use land, approximately 235,000 residents and an estimated $28.7 billion in damageable property.
Figure 2-2 shows the 0.2 percent (1/500) median ACE floodplain.
The frequency of observed historical floods is not directly comparable to the existing condition due to historical changes in the FRM system over time. Damage to the study area during known past floods would have been significantly reduced if the floods had occurred with presently existing FRM facilities completed and in operation. As a result, hydrologic frequency analysis and hydraulic modeling are necessary to evaluate the flood frequency and flood risk under existing and future conditions.
Figure 5-7 demonstrates the natural composite floodplain of the study area and areas susceptible to flooding if a breach in an existing levee was to occur during a flood event. For display purposes, the map includes dots where the hydraulic model was used to simulate a levee breach. The breach location is considered representative of the larger levee reach. The figures are provided over a range of flood frequencies from 50 percent (1/2) ACE to 0.2 percent (1/500) ACE. Since these maps do not account for levees providing any flood risk reduction, they do not represent actual flood risk. Rather, they demonstrate the areas vulnerable to flooding if a levee fails.
Figure 5-8 demonstrates how the floodplains have been altered by Federal and non-Federal levees within the study area. The Risk and Uncertainty (R&U) floodplain map shows an area flooded by a breach if the levee does not meet minimum assurance criteria of 90 percent. In other words, the R&U floodplain maps demonstrate how certain the levee system is able to prevent the area from being flooded for a given ACE event. If a levee has less than 90 percent assurance of passing the flood event, the area corresponding to an assumed breach is plotted on the map. The other way to interpret this is there is at least a 10 percent chance that the levee would fail at these locations for the given flood magnitude and the results of said failure. For display purposes the map includes dots where the hydraulic model was used to simulate a levee breach. The breach location is considered representative of the larger levee reach.
The performance based R&U floodplain maps show that the north and central Stockton areas have the highest probability of being flooded from the Delta Front levees. The maps also indicate the potential flood depths associated with a levee failure and can be used to assess flood losses including life safety, property damage, debris disposal, stormwater pollution, etc.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-7: Natural Composite Floodplain—Alternative 1 (No Action Plan) ATTACHMENT D 1151
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-8: R&U Composite Floodplain—Alternative 1 (No Action Plan) ATTACHMENT D 1152
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San Joaquin County, CA Affected Environment and Environmental Consequences Most of the study area is currently designated by the NFIP as shaded zone x. Structures built within the NFIP shaded zone x are not required to be elevated above the 1 percent (1/100) ACE base floodplain.
However, these areas are still considered to have a moderate to low risk of flooding due to hydrologic, hydraulic and geotechnical uncertainties. In other words, levees are not considered to be 100 percent reliable and there is always some risk of flooding from a levee breach.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Assessment Methods
This assessment is based upon analysis of historical flood events and adjustments to reflect existing and future hydrologic and hydraulic conditions. Analysis was performed using recorded gage data, hydrologic models, hydraulic models, geotechnical models and flood damage models. Analysis of alternative plans was performed by modifying the models to reflect the features of each alternative. The analysis incorporated a literature review and applied accepted standards of professional practice. The models and other analyses are consistent with the requirements of ER 1100-2-8162, Incorporating Sea Level Changes in Civil Works Programs, Curve II to account for sea level change over the design life of the project. Curve II was selected as a mean estimate, due to the uncertainty and consequences of flooding in a highly urbanized area. More detailed information on the hydrologic and hydraulic analysis is available in the appendices.
Basis of Significance
Effects on hydrology and hydraulics were considered significant if an alternative would result in any of the following conditions. These effects are based on NEPA standards, State CEQA Guidelines Appendix G (14 CCR 15000 et seq.) and standards of professional practice. Substantially alter the existing drainage patterns of the site or area, including through the alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on or off site.
Create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff. Place housing within a 1 percent (1/100) ACE special flood hazard area. Place within a 1 percent (1/100) ACE special flood hazard area structures which would impede or redirect flood flows.
Expose people or structures to a significant risk of loss, injury or death involving flooding.
The primary purpose of the proposed project is to reduce the risk of flooding in the study area. The alternatives being considered would not place housing within a 100-year flood hazard area so this significance criteria is not addressed further.
ALTERNATIVE 1 – NO ACTION
Under the No Action Alternative, USACE would take no additional action to reduce the probability of flooding in the study area. The probability of flooding would be similar to the existing condition. In the future, the probability of flooding within the Delta Front areas will increase due to increases in sea level.
The R&U floodplain map for Alternative 1 is provided in Figure 5-8. The map shows the area flooded by a breach in the levee if the levee does not meet minimum assurance criteria of 90 percent. The definition of the R&U floodplain map is provided in the description of the existing conditions.
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San Joaquin County, CA Affected Environment and Environmental Consequences The consequences associated with a flood could increase in the future as the damageable property in the floodplain increases due to development. However, Stockton, Manteca, Lathrop and the surrounding urban (10,000 people or more) and urbanizing areas are required by 2016 to develop a plan to obtain 0.5 percent (1/200) ACE level of flood protection by 2025, as required by SB 5.
Future projects under the No Action Alternative would be expected to comply with current and future regulations and design requirements of local, State and Federal agencies to limit changes in hydrology.
Therefore, the No Action Alternative would not substantially alter existing drainage patterns, including through the alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on or off site.
The No Action Alternative would not contribute runoff water that would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff; and would neither increase nor decrease the exposure of people or structures to a significant risk of loss, injury or death involving flooding. Therefore, the No Action Alternative would have a less than significant effect for these significance criteria.
Implementation of future FRM projects and compliance with flood regulations by local and State entities would ensure that the No Action Alternative would neither place housing nor structures within a 1 percent (1/100) ACE special flood hazard area nor place within a 1 percent (1/100) ACE special flood hazard area that would impede or redirect flood flows. Therefore, the No Action Alternative would have no effect.
ALTERNATIVE 7A
Under Alternative 7a, portions of North and Central Stockton are provided with additional FRM benefits through select levee raises and geotechnical improvements. The R&U floodplain map for Alternative 7a is provided in Figure 5-9. The map shows the area flooded by a breach of levees that do not meet minimum assurance criteria of 90 percent for a given flood event magnitude. The comparison of the No Action Alternative and Alternative 7A R&U floodplain maps indicate the increased FRM benefits of the project.
Hydraulic models associated with Alternative 7a were modified to reflect the increased levee height measures, which would be limited to only levees that provide FRM to the study area. The levee along the right bank of French Camp Slough would be extended upstream to the UPRR rail yard to optimize protection to Central Stockton. Improving the levees in the project area would not increase stages and flows for channels and sloughs adjacent to north and central Stockton. Alternative 7a would have a significant beneficial impact by reducing the exposure of people or structures to significant risk of loss, injury or death involving flooding in the study area.
Alternative 7a includes construction and operation of two closure structures; one at Fourteenmile Slough and one at Smith Canal. These structures would reduce flood risk to north and central Stockton. The closure structures on Fourteenmile Slough and Smith Canal are intended to reduce the water surface elevation to areas behind those structures for floods greater than about a 30 percent ACE event. These structures reduce the probability of a levee failure by reducing the stage (hydraulic loading) of the levee. In addition, these structures reduce the consequences of a breach by limiting the volume of water that could flow through a breach from the Delta. Note that potential adverse impacts of the closure structures to water quality, waters of the U.S. and fisheries are discussed in the appropriate sections.
Alternative 7a would not substantially alter the existing drainage patterns of the site or area, including through alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on or off site. However, a detailed sedimentation analysis has not been completed. The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce overall retention time and allow ATTACHMENT D 1154
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San Joaquin County, CA Affected Environment and Environmental Consequences sediment to fall out of suspension within portions of these channels. These reaches do not appear to have significant sources of suspended sediment. So, these impacts are considered less than significant.
Alternative 7a would not contribute runoff water in excess of current baseline conditions and would not exceed the capacity of existing or planned stormwater drainage systems, and so would have no effect.
Alternative 7a includes the placement of Fourteenmile Slough and Smith Canal closure structures within a 1 percent (1/100) ACE special flood hazard area. These structures would impede or redirect flood flows.
However, these structures would either reduce or not change flood stages for a 1 percent (1/100) ACE flood.
These impacts are considered to be beneficial or to have no effect.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-9: R&U Composite Floodplain—Alternative 7a
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 7B
Alternative 7b is the same as Alternative 7a, except that it includes additional levee fixes in RD 17 and lengthening and raising the RD 17 tieback levee. The R&U floodplain map for Alternative 7b is provided in Figure 5-10 and shows the area flooded by a breach for levees that do not meet minimum assurance criteria of 90 percent. The potential impacts of the levee improvements and closure structures are the same as described under Alternative 7a. For events greater than 1 percent (1/100) ACE the improvements to the RD 17 tieback levee would decrease the volume of floodwaters that would outflank the tieback levee and be conveyed by the floodplain east of the SJR channel in the No Action Alternative. In the No Action Alternative these floodwaters are conveyed by the floodplain within RD17 before discharging to the SJR and Stockton Deep Water Ship Channel. Alternative 7b improvements would reduce the probability of this outflanking and the floodwaters would instead be conveyed by the Old River, Middle River and SJR channels, resulting in increased channel stages for events greater than 1 percent (1/100) ACE event. The estimated increase in stage and flow for these channels is described in the Hydraulic Design Addendum.
Alternative 7b would have a significant beneficial impact by reducing the exposure of people or structures to a significant risk of loss, injury or death involving flooding in the study area.
Alternative 7b would not substantially alter existing drainage patterns of the site or area, including through course alteration of a stream or river in a manner that would result in substantial erosion or siltation on or off site, but a detailed sedimentation analysis has not been completed. The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce the overall retention time and allow sediment to fall out of suspension within portions of these channels. These reaches do not appear to have significant sources of suspended sediment. The RD17 tieback levee improvements would be unlikely to increase erosion or siltation on or off site. These impacts are considered less than significant.
Although Alternative 7b improvements to the RD 17 tieback levee would likely increase stages along Old River, Middle River and SJR for events greater than 1 percent (1/100) ACE event, the increase in flood risk associated with these changes would be mitigated by the levee height and geotechnical improvements to the levees within the study area. The increase in flood risk outside the study area is considered less than significant, because the changes are for events rarer than a 1 percent (1/100) ACE event.
Alternative 7b would place within a 1 percent (1/100) ACE special flood hazard area structures that would impede or redirect floodflows. However, these structures would either reduce or not change flood stages for a 1 percent (1/100) ACE flood; therefore, the impact would be less than significant.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-10: R&U Composite Floodplain—Alternative 7b
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 8A
Alternative 8a is similar to Alternative 7a, except that it includes additional levee improvements on the Lower Calaveras River and the Stockton Diverting Canal. The hydraulic design must meet current USACE design requirements, which combine the fix-in-place measures of cutoff wall, seismic deep soil mixing, seepage berm and levee geometry improvements. The R&U floodplain map for Alternative 8a is provided in Figure 5-11. The map shows the area flooded by a breach for levees that do not meet minimum assurance criteria of 90 percent.
Alternative 8a includes construction and operation of two closure structures; one at Fourteenmile Slough and one at Smith Canal. These structures would reduce flood risk to north and central Stockton. The closure structures on Fourteenmile Slough and Smith Canal are intended to reduce the water surface elevation to areas behind those structures for floods greater than a 30 percent ACE event. These structures reduce the probability of a levee failure by reducing the stage (hydraulic loading) of the levee. In addition, these structures reduce the consequences of a breach by limiting the volume of water that could flow through a breach from the Delta. Alternative 8a would have a significant beneficial impact by reducing the exposure of people or structures to a significant risk of loss, injury or death from flooding in the study area.
Alternative 8a would not substantially alter the existing drainage patterns of the site or area, including through the alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on or off site, but a detailed sedimentation analysis was not done. The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce overall retention time and allow sediment to fall out of suspension within portions of these channels. These reaches do not appear to have significant sources of suspended sediment. These impacts are considered less than significant.
Alternative 8a would neither contribute runoff water in excess of current baseline conditions nor exceed the capacity of existing or planned stormwater drainage systems and, therefore, would have no effect.
Alternative 8a includes the placement of Fourteenmile Slough and Smith Canal closure structures within a 1 percent (1/100) ACE special flood hazard area. These structures would impede or redirect flood flows.
However, these structures would either reduce or not change flood stages for a 1 percent (1/100) ACE flood.
These impacts are considered to be beneficial or to have no effect.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-11: R&U Composite Floodplain—Alternative 8a
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 8B
Alternative 8b is the same as Alternative 8a, except that it includes additional levee fixes in RD 17 and lengthening and raising the RD 17 tieback levee. The potential impacts of the levee improvements and closure structures are the same as described under Alternative 8a for north and central Stockton. The R&U floodplain map for Alternative 8b is provided in Figure 5-12. The map shows the area flooded by a breach for levees that do not meet minimum assurance criteria of 90 percent.
For events greater than 1 percent (1/100) ACE, the improvements to the RD 17 tieback levee would decrease the volume of floodwaters that would outflank the tieback levee and be conveyed by the floodplain east of the SJR channel in the No Action Alternative. In the No Action Alternative, these floodwaters pond in the downstream urbanized portion of the RD17 floodplain before discharging to the SJR and Stockton Deep Water Ship Channel. Alternative 8b improvements would prevent this outflanking and the floodwaters would instead be conveyed by the Old River, Middle River and SJR channels, resulting in increased channel stages for events greater than 1 percent (1/100) ACE event. Alternative 8b would have a significant beneficial impact in reducing the exposure of people or structures to a significant risk of loss, injury or death involving flooding in the study area.
Alternative 8b would not substantially alter the existing drainage patterns of the site or area, including through course alteration of a stream or river, in a manner that would result in substantial erosion or siltation on or off site, but a detailed sedimentation analysis was not completed. The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce the overall retention time and allow sediment to fall out of suspension within portions of these channels. These reaches do not appear to have significant sources of suspended sediment. The improvements to the RD17 tieback levee would be unlikely to increase erosion or siltation on or off site. Therefore, these impacts are considered less than significant.
Although Alternative 8b improvements to the RD 17 tieback levee may increase stages along Old River, Middle River and SJR for events greater than 1 percent (1/100) ACE event, the increase in flood risk associated with these changes would be mitigated by levee height and geotechnical improvements to the levees. The increase in flood risk outside the study area is not considered significant, because the changes are for events rarer than a 1 percent (1/100) ACE event. Therefore, impacts are less than significant.
Alternative 8b includes the placement of Fourteenmile Slough and Smith Canal closure structures within a 1 percent (1/100) ACE special flood hazard area. These structures would impede or redirect flood flows.
However, these structures would either reduce or not change flood stages for a 1 percent (1/100) ACE event and, therefore, would have a less than significant impact.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-12: R&U Composite Floodplain—Alternative 8b
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 9A
Alternative 9a includes the same levee improvements and closure structures as Alternative 7a. In addition to these improvements, it includes a diversion structure on the Stockton Diverting Canal that would divert some high flows from the Stockton Diverting Canal into a new flood bypass (Mormon Channel flood bypass) in Old Mormon Slough. Flows into the Mormon Channel would occur every 5 years. The R&U floodplain map for Alternative 9a is provided in Figure 5-13 and shows the area flooded by a breach for levees that do not meet minimum assurance criteria of 90 percent. Alternative 9a would have a significant beneficial impact in reducing the exposure of people or structures to a significant risk of loss, injury or death involving flooding in the study area.
Alternative 9a would alter the course of a stream or river in a manner that would result in erosion or siltation on or off site. Construction and operation of a flood bypass in Old Mormon Slough would reduce the volume of flood flows moving through the Stockton Diverting Canal and the Lower Calaveras River in comparison with current conditions every other year. It would reintroduce flood flows to Mormon Channel every 5 years. The diverted flows will contain suspended sediments that will likely fall out of suspension in the Stockton Turning Basin. The bypass diversion may increase the amount of sediment deposition. However, in comparison to existing deposition rates, this impact is less than significant.
The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce the overall retention time and allow sediment to fall out of suspension with portions of these channels. A detailed sedimentation analysis was not completed. However, these reaches do not appear to have significant sources of suspended sediment. Therefore, these impacts are considered less than significant.
Alternative 9a would not contribute runoff water in excess of current baseline conditions and would not exceed the capacity of existing or planned stormwater drainage systems. Therefore, impacts would be less than significant.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-13: R&U Composite Floodplain—Alternative 9a
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 9B
Alternative 9b is similar to Alternative 9a, but includes additional levee fixes in RD 17 and improvements and an extension of the RD 17 tieback levee. The hydraulic design must meet current USACE design requirements that combine the fix-in-place measures of cutoff wall, seismic deep soil mixing, seepage berm and levee geometry improvements. The R&U floodplain map for Alternative 9b is provided in Figure 5-14.
The map shows the area flooded by a breach for levees that do not meet minimum assurance criteria of 90 percent. Alternative 9b would have a significant beneficial effect in reducing the exposure of people or structures to a significant risk of loss, injury or death involving flooding in the study area.
Alternative 9b would alter the course of a stream or river in a manner that would result in erosion or siltation on or off site. Construction and operation of a flood bypass in Old Mormon Slough would reduce the volume of flood flows in the Stockton Diverting Canal and the Lower Calaveras River in comparison with current conditions every other year. It would reintroduce flood flows to Mormon Channel every 5 years. The bypass diversion may increase the amount of sediment deposition in the Stockton Turning Basin, but in comparison to existing deposition rates this impact is less than significant.
The closure structures on Fourteenmile Slough and Smith Canal may reduce the tidal exchange within these reaches by constricting the channel dimensions at the project site. This may reduce the overall retention time and allow sediment to fall out of suspension with portions of these channels. A detailed sedimentation analysis was not completed. However, these reaches do not appear to have significant sources of suspended sediment. Therefore, these impacts are considered less than significant.
Although Alternative 9b levee improvements to the RD 17 tieback levee would likely increase stages along Old River, Middle River and SJR for events greater than 1 percent (1/100) ACE event, it would not lead to changes in flooding downstream of the levee improvements. Further, Alternative 9b would not contribute runoff water in excess of current baseline conditions, nor exceed the capacity of existing or planned stormwater drainage systems. Therefore, impacts would be less than significant.
MITIGATION
For each of the alternatives, the proposed levee improvements would not result in substantial changes in water surface elevation and are, therefore, less than significant and no mitigation is needed. The closure structures on Fourteenmile Slough and Smith Canal are intended to reduce water surface elevation to areas behind those structures. They would reduce the stages for floods larger than a 30 percent (1/3) ACE event.
This would be a beneficial FRM impact to north and central Stockton. No mitigation is needed.
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San Joaquin County, CA Affected Environment and Environmental Consequences Figure 5-14: R&U Composite Floodplain—Alternative 9b
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WATER QUALITY
This section describes the affected environment and environmental consequences relating to the water quality of surface waters. The significance of the impacts and mitigation measures to reduce impacts are also discussed. Effects on waters of the U.S. and wetlands are addressed separately in Section 5.7.
ENVIRONMENTAL SETTING
Regulatory Framework
Laws, regulations and requirements that apply to water quality are listed below and summarized in Chapter 7, Compliance with Applicable Laws, Policies and Plans.
Federal
CWA Sections 404, 402, 401, 303
NPDES
State
Delta Plan (2013)
Porter-Cologne Water Quality Control Act
Statewide NPDES general permit for stormwater discharges associated with construction activities, as amended (Order 2009-0009-DWQ)
Local
City of Lathrop General Plan (Goal 5, Policy 6; Goal 10) City of Manteca General Plan (Implementation RC-I-24) City of Stockton General Plan
San Joaquin County General Plan (Objective 1; Objective 5, Policies 2 and 11) Water Quality Control Plan (Basin Plan) for the San Francisco Bay/San Joaquin Delta Estuary (1995, 2006, 2009)
Existing Conditions
The project area is in the southeastern portion of the Delta, within the legal boundary of the Delta, as defined by Section 12220 of the California Water Code. The legal Delta encompasses an area of 851,000 acres (of which 135,000 acres consist of waterway, marshland or other water surfaces). The Delta is divided into a Primary and Secondary Zone, as defined by the Delta Protection Act of 1992. Land uses in the Primary Zone are regulated to protect the area for agriculture, wildlife habitat and recreational uses. The Secondary Zone, where urban development activities occur, is where efforts should be taken to ensure that these activities do not adversely affect Delta waters, Primary Zone habitat or recreational uses. The SJR delineates the boundary between the Primary Zone to the west and the Secondary Zone to the east. The proposed project is located entirely within the Secondary Zone.
Surface waters in the Lower SJR Watershed include the river and its tributaries and secondary canals and irrigation ditches. Bear Creek, Mosher Slough, Tenmile Slough, Fivemile Slough, French Camp Slough and the Calaveras River all converge with the SJR in the vicinity of Stockton. The Stockton Diverting Canal routes water from Mormon Slough to the Calaveras River. Secondary canals and irrigation ditches are generally parallel to the larger surface waters in the project.
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San Joaquin County, CA Affected Environment and Environmental Consequences Surface Water Quality
In the San Joaquin Hydrologic Region, the overarching water quality issues are a result of depleted freshwater flows, municipal and industrial waste water discharges, salt loads in agricultural drainage and runoff and other pollutants associated with agricultural irrigation and production (such as nutrients, selenium, boron and organophosphate pesticides) (Central Valley RWQCB, 2007). In urban areas, stormwater drainage systems may contain heavy metals and chemicals generated from vehicles and yard chemicals from residential and commercial areas.
Water quality in the Delta and portions of the SJR are heavily influenced by the operations of the CVP and the SWP. Generally, Delta water quality is best during the winter and spring months and poorer through the irrigation season and early fall. Water quality in the SJR is influenced by factors such as rain and snowmelt runoff, reservoir operations and irrigation return flows in the SJR basin. Agricultural return flows commonly discharge elevated salt loads into the SJR. The SWRCB has set flow and water quality objectives at Vernalis, located just upstream from the proposed project. To meet the Vernalis objectives, the USBR supplements flows to the SJR with releases from New Melones Reservoir on the Stanislaus River (Northeastern San Joaquin County Groundwater Banking Authority 2004:44,45).
The latest version of the Section 303(d) list for California issued by the SWRCB (approved October 11, 2011) identifies impaired status for waterways in the project area. These impaired waterways include Mosher Slough, Tenmile Slough, Fourteenmile Slough, Stockton Ship Channel, Smith Canal, lower SJR, Old Mormon Slough, French Camp Slough and Duck Creek (Walker Slough). Potential source of pollution for all of the listed constituents in the basin include agriculture, urban runoff, storm sewers, resource extraction, municipal point sources and contaminated sediments (ICF 2014). The Environmental Addendum includes a table that identifies the impairment for each waterway. Impairments in the project area include: chlorpyrifos, dichlorodiphenyltrichloroethane (DDT), diazinon, dioxin, furan compounds, Group A pesticides, mercury organic enrichment/low DO, polychlorinated biphenyls (PCBs), Escherichia coli, sediment toxicity, electrical conductivity (EC), pathogens, invasive species and unknown toxicity.
The Stockton Deep Water Ship Channel portion of the SJR is being addressed by a Total Maximum Daily Load (TMDL) for dissolved oxygen (DO), which increased in the channel since 2007 after the City of Stockton installed a nitrificiation system at the wastewater treatment plant to reduce ammonia in the effluent (CSWRC 2012:1). TMDLs were initiated for organophosphorous pesticides (i.e., diazinon and chlorpyrifos), salinity and boron and selenium in the SJR watershed and for total dissolved solids (TDS) and mercury in Delta channels. TMDLs for the other listed pollutants are scheduled to be developed at various times over the next 10 years in accordance with priorities contained in the Section 303(d) list.
Major monitoring programs in the SJR include the DWR Municipal Water Quality Investigations Program and the DWR D-1485 Water Quality Monitoring Program. The City of Stockton also monitors ambient water quality to assess potential effects associated with discharges from the Stockton Regional Wastewater Control Facility. Data are collected at 5 water quality monitoring sites near RD 17 along the SJR. The Mossdale Bridge sampling site at the I-5 crossing over the SJR is near RD 17. The Vernalis sampling site is located near the town of Vernalis just upstream from the proposed project.
Salinity in the Delta is the result of tidal exchange with San Francisco Bay, variations in freshwater inflow from the San Joaquin and Sacramento Rivers, agricultural and urban exports/diversions and agricultural return flows. The salinity of surface waters is often measured by the concentration of TDS and EC, commonly used as a surrogate parameter upon which to evaluate TDS. Discharges from agriculture, wetlands, mines and industries have had greater concentrations during critical (drought) water years than during wet or above-normal water years. The Water Quality Control Plan for the Sacramento-San Joaquin River Basins (Basin Plan), adopted by the Central Valley RWQCB in 2006 and most recently updated in 2011, addresses water quality objectives and standards in the Basin Plan area. Historical data indicate that ATTACHMENT D 1168
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San Joaquin County, CA Affected Environment and Environmental Consequences seasonal water quality (April 1 to August 31) objectives for EC in the Delta were routinely exceeded in the SJR near Vernalis and at Mossdale Bridge; the standards were typically met at the other nearby monitoring locations (City of Lathrop 2001: 4.2-14).
Historical data show that the dissolved oxygen concentration regularly falls below the Basin Plan’s minimum standards in the SJR near Stockton (City of Lathrop 2001: 4.2-15). Low or negative streamflow past Stockton reduces dilution and mixing, which reduces re-aeration of the water. Oxygen depletion in the water bodies in the Central Valley is typically highest in late summer and fall, when high temperature reduces the oxygen-carrying capacity of the water. This suggests that dissolved oxygen levels may be influenced by physical processes (temperature, saturation capacity) rather than biological processes (respiration and primary production) (SWRCB 2010: 3-2).
The distribution of ammonia in freshwater rivers and lakes is highly variable regionally, seasonally and spatially and depends on the level of productivity of the water body and the extent of inputs from organic matter. Ammonia may be acutely toxic at high concentrations or chronically toxic at low concentrations, depending on the length of exposure. Historical data indicate that ammonia concentrations at monitoring sites near RD 17 were below levels that would cause either acute or chronic toxicity (City of Lathrop 2001:
4.2-17). Kjeldahl nitrogen is nitrogen in the form of organic proteins or their decomposition product, ammonia, as measured by the Kjeldahl method. During December 2007, Kjeldahl nitrogen levels near RD 17 had a high of 1.4 mg/L. Dissolved inorganic nitrogen is a measure of total ammonium (NH4), nitrate (NO3
) and nitrite (NO2), the nitrogen forms immediately available for assimilation by phytoplankton.
During December 2007, dissolved inorganic nitrogen levels were found to be 3.74 mg/L. The high values observed in the Delta may be due to runoff and drainage from agricultural operations on the SJR (SWRCB 2010: 3-5, 3-6).
Trace elements may affect aquatic organisms directly or may affect human health or wildlife through water consumption or through bioaccumulation in fish or shellfish consumed by humans or high-end predators.
The State is currently developing a TMDL program for mercury in the Delta that would result in the identification of a regulatory target(s), determination of sources and their associated loads, development of a quantitative model to predict loading and implementation of a mercury control program to reduce loads to comply with water quality objectives.
Results from recent Delta sampling showed concentrations above historical ranges (SWRCB 2010: 3-11 to 3-17). Measured parameters exhibited seasonal variation and changes in response to significant rainfall events or changes in flow rates.
Gates
Permanent and temporary gates and barriers are present throughout the Delta and Suisun Marsh. They are used to manage water quality, keep fish away from water supply export pumps, maintain water levels and reduce flood risk (Wilson: 2013). Additional gates are under study, such as those associated with the Franks Tract Project and the Two-Gates Project. Ongoing operational considerations include management of increased aquatic predator populations and passage for recreational uses.
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ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
A project alternative would create a significant water quality impact if it would:
Violate any water quality standards or waste discharge requirements or otherwise substantially degrade water quality; or
Create or contribute runoff water that would provide substantial, additional sources of non-point source polluted runoff.
Since the Draft FR/EIS/EIR was published, Moffatt & Nichol completed hydrodynamic modeling and a water quality residence time analyses for the gated fixed wall structure proposed by SJAFCA as part of their early implementation project. The modeling is described in Appendix B of the Smith Canal Gate Project EIR (State Clearinghouse No. 2014062079) (November 2015) and results are discussed in Section
3.2 of the EIR. Both documents are available on SJAFCA’s website (http://www.sjafca.com/smith_canal_closure.php) and are available for inspection at SJAFCA’s offices at 22 E. Weber Ave., Suite 301, Stockton at 95202. This information is incorporated by reference and summarized in the sections below describing impacts. The following text is from the EIR:
MIKE-21 software was used to develop a model of Smith Canal, Atherton Cove and the nearby section of the San Joaquin River. The model was used to simulate velocity, stage, transport and residence time for each alternative. Residence time refers to the average amount of time that a particle spends in a particular system, providing a measure of the rate at which waters in a particular system would be renewed. Residence time provides a method for assessing water quality.
The model results indicate that residence time would be unaffected by any of the proposed gated fixed wall structures because the gate opening would still be sufficiently large to enable tidal flow to propagate into Smith Canal and Atherton Cove without causing tidal muting. The model results demonstrate that residence time varies greatly from the outer portion of Smith Canal, through the canal and into Yosemite Lake because of the narrow and elongated extent of Smith Canal. Typical residence times near the mouth of Smith Canal are around 1 day, whereas residence times approximately midway into the canal approach 30 days.
Residence times in the back of the canal and into Yosemite Lake exceed 40 days. The residence time in Atherton Cove is very short, less than 2 days, indicating good flushing and circulation.
While acknowledging the potential consequences of continued elevated flood risk, this impact analysis evaluates potential impacts of the 6 alternatives in relation to continuation of current conditions and maintenance practices that would be reasonably expected to occur in the foreseeable future if the project were not implemented.
ALTERNATIVE 1 - NO ACTION
For the purpose of this environmental impact analysis, the No Action Alternative assumes that no construction activities or levee vegetation removal beyond routine maintenance would occur. The water quality conditions would remain as described for existing conditions. The current level of risk would remain for a levee failure and flooding within the project area. Flooding of urban and agricultural lands would be likely to result in pollution of the SJR and contribute to temporary and long-term water quality degradation and nonattainment of designated uses. Flooding could inundate urban areas, exposing them to petroleum products, solvents, pesticides, nutrients and other pollutants. These materials could be transported onto adjacent agricultural lands and into waterways. Where flooding occurs on agricultural lands, runoff of pesticides and nutrients into natural areas would be expected. Polluted flood flows would either return to the SJR via overland flow or be collected by drainage systems and discharged to the SJR.
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San Joaquin County, CA Affected Environment and Environmental Consequences The magnitude of the impacts would depend upon the location of the levee breach, severity of the storm and river flows at the time of flooding. Predicting these events and providing a determination of significance is not possible based on the information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
ALTERNATIVE 7A
Construction activities have the potential to temporarily impair water quality if disturbed and eroded soil, petroleum products or construction-related wastes (e.g., cement and solvents) are discharged into receiving waters or onto the ground where they can be carried into receiving waters. Soil and associated contaminants that enter receiving waters can increase turbidity, stimulate algae growth, increase sedimentation of aquatic habitat and introduce compounds that are toxic to aquatic organisms. Accidental spills of constructionrelated substances such as oils and fuels can contaminate both surface water and groundwater. The extent of potential impacts on water quality would depend on the tendency for erosion of soil types encountered, types of construction practices, extent of the disturbed area, duration of construction activities, timing of particular construction activities relative to rain events, proximity to receiving water bodies and sensitivity of those water bodies to contaminants.
Alternative 7a would require extensive ground-disturbing activities including borrow site activities, closure structures, deep soil mixing and conventional cutoff walls. Much of the construction activities would occur near local drainages and waterways that could be contaminated by soil or construction substances. These waterways include the SJR, Mosher Slough, Tenmile Slough, Fourteenmile Slough, the Lower Calaveras River, Smith Canal, French Camp Slough and Duck Creek, in addition to agricultural drainage canals and local ponds.
Temporary impacts could result from construction of the cutoff walls and seismic remediation. Cutoff walls and seismic remediation would be constructed using soil-bentonite slurry, which has a fluid consistency during installation. The cutoff walls would be installed through the existing levee and extend to depths 50 to 70 feet below the levee crown. Seismic remediation involves installation of a grid of drilled soil-cement mixed columns, aligned longitudinally with and transverse to, the alignment of the levee extending beyond the levee prism. Improper handling or storage of the slurry or soil-cement material could result in releases to nearby surface water, degrading water quality. Further, seepage berms and realignment of the levee would require relocation of agricultural ditches and other permanent structures that could result in release of soil or other discharges to surface water.
The closure structures proposed for Smith Canal and Fourteenmile Slough would consist of a fixed sheet pile wall structure with an opening gate structure to allow for navigation and tidal movement of water. The opening portion would be a gate structure 50 feet wide attached to a concrete foundation using stainless steel anchor bolts. A sheet pile floodwall would be constructed adjacent to the control structures to tie the structures into the adjacent levee or high ground areas.
The construction of the closure structures is described in Sections 4.3.10 and 4.5.5. The gates would permanently affect about 0.5 acres of intertidal habitat at Fourteenmile Slough and 0.5 acres of tidally influenced open water riverine habitat at Smith Canal. Construction activities would affect an additional 1 acre of intertidal habitat at Fourteenmile Slough and 3 acres of tidally influence open water riverine habitat at Smith Canal. Temporary construction impacts would include localized increases in turbidity and unintended introduction of chemical contaminants.
At the time the Draft FR/EIS/EIR was published, hydrodynamic or residence time modeling for the closure structure at Smith Canal and the Draft FR/EIS/EIR reported no potential permanent and temporary, but recurring, water quality impacts including decreased dissolved oxygen and changes in salinity gradient eastward of the Fourteenmile Slough and Smith Canal gate and a finding of significant and unavoidable for ATTACHMENT D 1171
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San Joaquin County, CA Affected Environment and Environmental Consequences impacts associated with the closure structures and their operation. Modeling results show that water residence time in Smith Canal and Atherton Cove would change very little if a closure structure with a 50 foot wide gate where constructed at the mouth of Smith Canal. The model results showed a slight increase in residence time at the upstream end of Smith Canal ( an increase from approximately 41 days to 42 days), but a slight decrease in residence time at the upstream end of Atherton Cover (a decrease from approximately 1.5 days to 1.4 days). The modeling results also concluded that the effect of the gated fixed wall structure on accumulation of contaminants organic material and nutrients would be less than significant and no mitigation would be necessary (ICF 2015). The closure structure on Fourteenmile Slough is expected to result in less than significant impacts on water quality because the design and operation is similar to the Smith Canal closure structure.
The gates would be exercised briefly (closed and immediately opened) once or twice a year. The gate would be closed when the delta stage is at 8.0 feet NAVD88 and rising and would be opened when the delta stage was 8.0 feet NAVD88 and falling. The gate would also be opened if the stage on the slough side of the gate rose higher than the delta stage. This would allow accumulated interior drainage behind the gate to flow out.One or both gates could be closed indefinitely in case of a levee failure occurred along Smith Canal or Fourteenmile Slough. The gate would be reopened once the levee repairs were made.
Even with this regular connectivity, existing water quality eastward of the gates would likely degrade for dissolved oxygen and invasive species and experience temporary but recurring degradation when the gates are closed. This may be most pronounced when the gates are closed for a few days to a few weeks when flood events occur concurrent with high tides. In these situations, contaminants entering the waters may result in increased concentrations of chlorpyrifos, DDT, diasinon, dioxin, furan compounds, Group A pesticides, mercury organic enrichment/low dissolved oxygen, pathogens and PCBs. Operation of the gates could have significant short-term effects on water quality; however, mitigation measures (Section 5.5.10) were identified that would reduce these impacts to less than significant.
Construction of the closure structures has the potential to result in temporary significant impacts to water quality. Parts of the closure structures extend from each bank into a portion of the waterway and the Draft FR/EIS/EIR reported that these structures had the potential to result in significant and unavoidable impacts on water quality. Recent hydrodynamic modeling determined that these permanent physical features would have a less than significant impact on water quality. If the proposed project is authorized and funded, before construction begins a SWPPP and a Bentonite Slurry Spill Contingency Plan (BSSCP) would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 7a would have a less than significant impact on water quality. The closure structures on Fourteenmile Slough and Smith Canal would have less than significant impacts on water quality. Gate operation (Chapter 4) could have a significant impact that would be mitigated to less than significant through the measures described in Section 5.5.10.
ALTERNATIVE 7B
The short- and long-term impacts described for Alternative 7a also apply to Alternative 7b since the proposed actions under these 2 alternatives are the same for the north and central Stockton areas. In addition, Alternative 7b includes improvements along the northern and western levees of RD 17. The nature of the potential improvement impacts are the same as those described above. The difference would be an additional 20.7 miles of levee improvements under Alternative 7b and no closure structures are being considered in RD 17.
Impacts associated with construction of in-water features (closure structures) and operation of the gates are the same as those described in Section 5.5.4. If the proposed project is authorized and funded, before ATTACHMENT D 1172
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San Joaquin County, CA Affected Environment and Environmental Consequences construction begins a SWPPP and a BSSCP would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 7b would have less than significant impacts to water quality. The closure structures on Fourteenmile Slough and Smith Canal would have less than significant impacts on water quality. Operation of the closure structures could have significant temporary impacts on water quality, which would be reduced to less than significant through the mitigation measures described in Section 5.5.10.
ALTERNATIVE 8A
Alternative 8a would have similar impacts to those described for Alternative 7a. Alternative 8a extends further up the Lower Calaveras River and include improvements to the Stockton Diverting Canal levees.
Impacts associated with the construction and operation of in-water features (closure structures) would be the same as those described in Section 5.5.4. If the proposed project is authorized and funded, before construction begins a SWPPP and a BSSCP would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 8a would have a less than significant impact on water quality. The closure structures on Fourteenmile Slough and Smith Canal would have less than significant impacts on water quality. Operation of the closure structures could have significant temporary impacts on water quality that would be reduced to less than significant through the mitigation measures described in Section 5.5.10.
ALTERNATIVE 8B
Water quality impacts associated with this alternative would be similar in nature to those described for Alternative 7a, but would be potentially greater in extent because it would include improvements to an additional 20.7 miles of levee. Impacts associated with the construction and operation of in-water features (closure structures) would be the same as described in Section 5.5.4. If the proposed project is authorized and funded, before construction begins a SWPPP and a BSSCP would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 8b would have a less than significant impact on water quality. The closure structures on Fourteenmile Slough and Smith Canal could have significant temporary impacts on water quality that would be reduced to less than significant through the mitigation measures described in Section 5.5.10.
ALTERNATIVE 9A
Under Alternative 9a, similar activities to Alternatives 7a are proposed along the same linear extent with additional improvements in Old Mormon Slough. Water quality impacts would be similar in nature, but greater due to the increased footprint and volume of soils disturbed by construction of the Mormon Channel Flood Bypass. Impacts associated with construction and operation of in-water features (closure structures) is the same as described in Section 5.5.4. If the proposed project is authorized and funded, before construction begins a SWPPP and a BSSCP would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 9a would have a less than significant impact on water quality. The closure structures on Fourteenmile Slough and Smith Canal would have less than significant temporary impacts on water quality.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 9B
Under Alternative 9b, similar activities to Alternatives 7b are proposed along the same linear extent with the addition of improvements in Old Mormon Slough. Water quality impacts would be similar in nature, but greater due to the increased footprint and volume of soils disturbed by construction of the Mormon Channel Flood Bypass. Impacts associated with construction and operation of in water features (closure structures) is the same as described in Section 5.5.4. If the proposed project is authorized and funded, before construction begins a SWPPP and a BSSCP would be prepared and water quality certification from the RWQCB would be obtained. BMPs would be implemented to avoid, minimize and mitigate effects on water quality during construction. Therefore, the potential for release of soil or construction-related materials in the waterways and local agricultural drainage canals under Alternative 9b would have a less than significant impact on water quality. The closure structures on Fourteenmile Slough and Smith Canal would have less than significant temporary impacts on water quality.
MITIGATION FOR ALTERNATIVES
Avoidance and Minimization Measures (BMPs)
The contractor would prepare a spill control plan and a SWPPP prior to initiation of construction in accordance with guidance from the RWQCB, Central Valley Region. These plans would be reviewed and approved by USACE before construction begins. Implement appropriate measures to prevent debris, soil, rock or other material from entering the water. Use a water truck or other appropriate measures to control dust on haul roads, construction areas and stockpiles.
Implement appropriate measures for handling and disposing of concrete and concrete washout water.
Properly dispose of oil or other liquids.
Fuel and maintain vehicles in a specified area that is designed to capture spills. This area cannot be near any ditch, stream or other body of water or feature that may convey water. Fuels and hazardous materials would not be stored on site. Inspect and maintain vehicles and equipment to prevent dripping oil and other fluids. Schedule construction to avoid the rainy season as much as possible. If rains are forecasted during construction, erosion control measures would be implemented as described in the RWQCB Erosion and Sediment Control Field Manual.
Maintain sediment and erosion control measures during construction. Inspect the control measures before, during and after a rain event.
Train construction workers in SWPPP and how to respond to, control, contain and clean up spills. Revegetate disturbed areas in a timely manner to control erosion. Materials will be covered and protected from wind, rain and runoff to avoid unwarranted dispersal. Construct culverts at Moreing Road to slightly reduce residence time at the upstream end of Atherton Cove (by approximately 0.2 days).
Refine operational criteria to ensure that desired FRM benefits are achieved while avoiding degradation of water quality behind the closure structures.
In addition to the avoidance and minimization measures described above, design and operational criteria of the flood gates would be coordinated with RWQCB, NMFS, USFWS and CDFW to minimize potential water quality impacts. With mitigation and implementation of other CWA requirements, impacts associated with implementation of any of the alternatives (7a, 7b, 8a, 8b, 9a, 9b) would be less than significant.
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San Joaquin County, CA Affected Environment and Environmental Consequences
GROUNDWATER
This section describes the affected environment and the environmental consequences that would result from implementing the LSJR Project and discusses the significance of the impacts and mitigation measures to reduce impacts.
ENVIRONMENTAL SETTING
Regulatory Framework
Laws, regulations and requirements that apply to water quality are listed below and summarized in Chapter
7. Few specific requirements were developed for or applied to groundwater. Those that apply to surface waters provide a framework for considering groundwater resources.
Federal
CWA Sections 404, 402, 401, 303
State
Delta Plan (2013)
Porter-Cologne Water Quality Control Act
Water Quality Control Plan (Basin Plan) for the San Francisco Bay/San Joaquin Delta Estuary (1995, 2006, 2009, 2011)
Local
City of Lathrop General Plan (Goal 5, Policy 6; Goal 10) City of Manteca General Plan (Implementation RC-I-24) City of Stockton General Plan
Eastern San Joaquin County Groundwater Management Plan (2004) San Joaquin County General Plan (Objective 1; Objective 5, Policies 2 and 11) Existing Conditions
The SJR Hydrologic Region is divided into 3 groundwater basins, which are divided into 9 sub-basins totaling 9.7 million acres in area (DWR, 2009). The study area is associated with the Eastern San Joaquin and the Tracy Sub-basins. The Eastern tributaries of the LSJR are located in the Eastern San Joaquin Subbasin. Most of the fresh groundwater is unconfined and occurs at depths of less than 2,500 feet (DWR 2006:169-170). The shallower aquifers are used as sources of freshwater. The region heavily relies on groundwater, which accounts for about 30 percent of the annual water supply used for agricultural and urban purposes (DWR 2003:25). Groundwater is used when and where surface water is unable to fully meet demands and has been used conjunctively with surface water to meet water needs since the beginning of the region’s agricultural development.
Average annual seepage from surface water is estimated to be 141,127 AF (AF), average annual subsurface inflow is an estimated 3,586 AF and applied water recharge is 593,356 AF. Average annual agricultural and urban extractions are 761,828 and 47,493 AF, respectively. Thus, total estimated extraction exceeds total estimated recharge by 71,252 AF (DWR 2006:3).
Measurements since the 1960’s show that groundwater levels declined continuously, resulting in significant groundwater depressions below and east of the City of Stockton. The largest of these depressions reaches ATTACHMENT D 1175
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San Joaquin County, CA Affected Environment and Environmental Consequences depths of more than 40 feet below mean sea level (DWR, 2006). On the east side of the Delta, declining water levels caused a 16-mile saline front to move eastward at a rate of 140 to 150 feet per year (USACE, 2006). Groundwater nitrate levels are elevated in large areas south of Stockton and east of Manteca extending towards the San Joaquin-Stanislaus County line (DWR, 2006).
In the Eastern San Joaquin Sub-basin, shallow and saline groundwater occurs within about 10 feet of the ground surface (DWR, 2009). Groundwater levels in the project area are generally very shallow as a result of the low elevation and proximity to the SJR channel. There are also localized areas of high TDS, nitrate, chloride, boron and organic compounds. TDS in the Eastern San Joaquin Sub-basin averages 310 milligrams per liter (mg/L) and can range from 30 to 1,632 mg/L. A total of 191 public supply wells were tested from 1994 to 2000 for primary and secondary inorganic contaminants, radiological contaminants, nitrates, pesticides and volatile organic compounds. Thirty nine percent of the tested wells exceeded USEPA maximum contaminant levels (MCL) for secondary inorganics and 11 percent of the tested wells exceeded the MCL for pesticides.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Assessment Methods
This assessment is based upon a literature review and accepted standards of professional practice.
Basis of Significance
A project alternative would significantly impact groundwater if it would:
Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (if the production rate of preexisting nearby wells would drop to a level that would not support existing land uses or planned uses for which permits have been granted) or Substantially affect the quality of the groundwater supply.
ALTERNATIVE 1 - NO ACTION
Development within Stockton and surrounding areas could reduce recharge rates as the area of impervious surfaces increases and a larger volume of surface flows are collected by surface drains. If current groundwater management practices continue, levels will continue to decline, storage will continue to be reduced and portions of the aquifer could become unusable due to the advancing inflow of higher salinity water from the west. In addition, potential contamination resulting from a flood event could limit the availability of groundwater.
The maximum sustainable yield from the aquifer is 0.75 to 1 AF, per acre per year. For the Delta Water Supply Project (DWSP), the City of Stockton selected a target extraction rate of 0.6 AF, per acre per year to reverse the historic overdraft and saline intrusion (City of Stockton 2007a, 2008a). The DWSP includes a storage and recovery program to address the City’s long-term groundwater needs. In addition, the Eastern San Joaquin Groundwater Basin Management Plan includes groundwater banking and recharge projects, although specific implementation measures not been outlined. Although current groundwater supply is not sufficient for the anticipated growth, groundwater impacts would be reduced to less than significant through implementation of target extraction rates, banking projects and recharge projects. Further, compliance with local, Federal and State requirements would be implemented to reduce potential degradation of groundwater quality. Therefore, the No Action Alternative would have a less than significant impact on groundwater availability.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 7A
Under Alternative 7a, cutoff walls, including jet grouting, would be installed along 23.7 miles of levees around north and central Stockton. This alternative would reduce the flood risk to areas behind the levee.
The areas receiving increased protection are urban and mostly built out. Therefore, the current pattern of groundwater recharge and extraction would be expected to continue.
Use of cutoff walls introduces the potential for groundwater contamination during construction. Primary construction-related contaminants include sediment, oil and grease and hazardous materials. The slurry wall material is relatively benign and would not remain in a liquid state long enough to allow for significant lateral movement within the aquifer. Nevertheless, the release of contaminants into groundwater would be a significant impact.
In addition, cutoff walls could restrict the movement of groundwater towards and away from adjacent rivers, streams and canals, which could change localized near-surface groundwater levels in areas immediately adjacent to the cutoff wall. Shallow wells adjacent to the cutoff wall could be affected by changes in radial flow, either increasing yields or pumping costs. If yields decrease, a corresponding decrease in water quality could occur as the aquifer lowers and pumps take in more sediment. Cutoff walls may provide a potential benefit if they disrupt the eastward movement of saline waters.
Although some shallow wells near the cuttoff wall could be affected, recharge and overall flow to supply wells would not be appreciably affected. The proposed cutoff walls would reach depths of up to 70 feet.
Since the upper water-bearing zone, the Victor Formation, extends from the ground surface to a maximum depth of 150 feet and is hydraulically connected to the underlying Laguna Formation, the cutoff wall would not isolate any portion of the shallow water-bearing zone. The cutoff wall should not affect the utility of existing or future water supply wells.
In the Central Valley, two detailed technical studies of potential effects of cutoff walls on groundwater were completed in the Sacramento Basin. These studies were for the Natomas Levee Improvement Project and the Feather River West Levee Project/Sutter Basin Pilot Feasibility Study (SAFCA 2007, USACE and SBFCA 2013). Both of these studies found that groundwater elevation would change by 3 feet or less. No similar studies were conducted in the San Joaquin Basin. In the absence of any other data, this impact analysis assumes that the potential impact of cutoff walls on groundwater would be similar to that identified for the two studies in the Sacramento River Basin and changes to groundwater elevations would be 10 to 50 feet or more below ground surface in the project area (San Joaquin County 2007). Further, the implementation of the project would not change land use such that the rate of groundwater recharge would decrease or effect well yields. Therefore, Alternative 7a would have a less than significant impact on groundwater supplies. Since there is uncertainty regarding effects on groundwater, the CSRA has been revised to acknowledge this uncertainty.
ALTERNATIVE 7B
Alternative 7b proposes the same repairs as Alternative 7a, but would also include improvements on the northern, western and southern levees in RD 17 and a section of new levee in the southern part of RD 17.
Cutoff walls would be constructed on 34 miles of levee around north and central Stockton and RD 17.
Potential impacts are the same as those described for Alternative 7a. Like north and central Stockton, the future growth anticipated by the proposed General Plan for RD 17 would not substantially deplete groundwater supplies if the proposed target extraction rate of 0.6 AF, per acre per year is met (City of Stockton 2007a, 2008a). For the same reasons outlined in Alternative 7a, Alternative 7b would have a less than significant impact on groundwater supplies and a potentially significant construction-related impact on groundwater quality.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 8A
Alternative 8a proposes the same repairs as Alternative 7a, but also includes additional levee improvements on the Lower Calaveras River and along the Stockton Diverting Canal. Cutoff walls would be constructed on 31 miles of levee around north and central Stockton. For the same reasons outlined in Alternative 7a, Alternative 8a would have a less than significant impact on groundwater supplies and a potentially significant construction-related impact on groundwater quality.
ALTERNATIVE 8B
Alternative 8b proposes the same repairs as Alternative 7b, with some additional levee improvements on the Lower Calaveras River and on the Stockton Diverting Canal. Cutoff walls would be constructed on 45 miles of levee around north and central Stockton and RD 17. For the same reasons outlined in Alternative 7a, Alternative 8b would have a less than significant impact on groundwater supplies and a potentially significant construction-related impact on groundwater quality.
ALTERNATIVE 9A
Alternative 9a includes the same features as Alternative 7a, yet also includes establishing a flood bypass channel through Old Mormon Channel. About 20 miles of cutoff walls would be constructed in north and central Stockton. The establishment of Mormon Channel as a flood bypass could provide increased groundwater recharge. For the same reasons outlined in Alternative 7a, Alternative 9a would have a less than significant impact on groundwater supplies and a potentially significant construction-related impact on groundwater quality.
ALTERNATIVE 9B
Alternative 9b proposes the same repairs as Alternative 7b with the addition of channel modifications and related features in Old Mormon Slough to create a flood bypass. A total of 34 miles of cutoff walls would be constructed. The addition of flood flows to Old Mormon Slough could increase groundwater recharge.
For the same reasons outlined in Alternative 7b, along with the potential for increased recharge, Alternative 9b would have a less than significant impact on groundwater supplies and a potentially significant construction-related impact on groundwater quality.
MITIGATION
Potential impacts to groundwater that could result from construction of the cutoff wall would be mitigated through development and implementation of a BSSCP, also known as a frac-out plan. A BSSCP is typically developed for activities that involve the use of bentoninte materials. It is intended to minimize the potential for a frac-out associated with excavation and tunneling activities, provide for timely detection of frac-outs and ensure a “minimum-effect” response in the event of a frac-out and release of excavation fluid. It would reduce potential impacts to groundwater to less than significant.
WETLANDS AND OTHER WATERS OF THE UNITED STATES
This section describes the affected environment and environmental consequences relating to waters of the U.S., including wetlands, and discusses the significance of the impacts and mitigation measures to reduce impacts.
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San Joaquin County, CA Affected Environment and Environmental Consequences
ENVIRONMENTAL SETTING
Regulatory Framework
Laws, regulations and requirements that apply to water quality are listed below and summarized in Chapter
7. Federal
CWA Sections 404, 402, 401, 303
ESA (Federal and State)
EO 11990 (Protection of Wetlands)
State
California Native Plant Protection Act
Porter-Cologne Water Quality Control Act
Section 1600 of the California Fish and Game Code
Local
City of Lathrop General Plan (Goal 5, Policy 6; Goal 10) City of Stockton General Plan
San Joaquin County General Plan (Objective 1; Objective 5, Policies 2 and 11) San Joaquin County Multi-species Habitat Conservation and Open Space Plan (SJCMSCP, San Joaquin County 2000)
Water Quality Control Plan (Basin Plan) for the San Francisco Bay/San Joaquin Delta Estuary (1995, 2006, 2009, 2011)
Regulatory Definitions
“Waters of the United States” and wetlands are defined in 33 U.S.C. 1344. Waters of the U.S. include:
All waters that are currently used or were used in the past or may be susceptible to use in interstate or foreign commerce, including all waters that are subject to tidal ebb and flow; All interstate waters including interstate wetlands;
All other waters such as intrastate lakes, rivers, streams including intermittent streams), mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes or natural ponds, the use, degradation or destruction of which could affect interstate or foreign commerce; All impoundments of water otherwise defined as waters of the U.S. under the definition; Tributaries of waters identified above;
The territorial seas;
Wetlands adjacent to waters (other than waters that are themselves wetlands identifies above; Waters of the U.S. do not include prior converted cropland or waste treatment systems designed to meet the requirements of CWA are not waters of the U.S. “Wetlands” means areas that are inundated or saturated by surface or groundwater at a frequency and duration to support and that under normal circumstances do support, a prevalence of vegetation typically adapted to life in saturated soil conditions. Wetlands generally include swamps, marshes and bogs.
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San Joaquin County, CA Affected Environment and Environmental Consequences For other water features such as rivers, streams and ditches, the extent of potential USACE jurisdiction is determined by identification of the Ordinary High Water Mark, defined as “that line on shore established by the fluctuations of water and indicated by physical character of the soil, destruction of terrestrial vegetation, the presence of litter and debris or other appropriate means that consider the characteristics of the surrounding areas” (33 CFR §328.3[e]).
Existing Conditions
The LSJRFS project area supports waters of the U.S., including rivers, estuarine sloughs and wetlands. The wetlands and other waters of the U.S. in the project area are highly altered as a result of FRM projects, reclamation for agriculture and urbanization and navigation projects. These projects have resulted in general straightening and simplification of river, stream and slough structure.
The National Wetland Inventory (NWI) indicates several wetlands within and adjacent to the riparian zone of the SJR and its tributaries, but not none of these are in the footprint of proposed new levees.
Perennial Drainages
The perennial drainages in the project area are: SJR, lower Calavaras River, French Camp Slough, Duck Slough, Stockton Deepwater Ship Channel, Stockton Diverting Canal, Tenmile Slough, Fourteenmile Slough, Fivemile Slough, Smith Canal, Burns Cutoff, Mosher Slough/Creek, Paradise Cut, Old River North, Walthall Slough and Mormon Slough and Old Mormon Slough. The SJR and the lower reaches of its tributaries in the project area, the Stockton Deepwater Ship Channel and the sloughs around north Stockton are tidally influenced. Before construction of the Stockton Diverting Canal, Old Mormon Slough was perennial in most years. Today, the channel receives local stormwater runoff and intermittently contains water.
Perennial to Intermittent Drainages
Landside levee toe drains are present throughout the project area. Agricultural canals and ditches are present in agricultural lands outside urban areas. In the project area, most of these agricultural canals and ditches are located on Shima Tract, Wright-Elmwood Tract and in RD 17. Levee toe drains and agricultural ditches may contain water seasonally or year-round.
Ponds
Small ponds are located eastward of the SJR levee in RD 17. Manmade ponds exist in north Stockton and in the northern part of RD 17, but are part of residential developments and will not be affected by this project and are, therefore, not treated in this impact analysis.
Emergent Wetland
Narrow bands of emergent wetlands are present along some portions of the SJR, its tributaries and along the sloughs in the vicinity of north Stockton. Wetlands occupy both freshwater and brackish areas. For example, freshwater habitat exists along the SJR and upstream tributaries while the downstream sloughs, like Fourteenmile Slough are brackish. Greater expanses of emergent wetlands are present in areas that have a waterside bench in the canal such as the tip of RD 17 that joins French Camp Slough. Some depressions that exist along the lower levees and adjacent to the waterside or landside of the levees contain wetland attributes.
Toe drains and agricultural and roadside ditches are routinely maintained to maintain flow capacity for FRM or agricultural purposes and, therefore, are frequently cleared of vegetation. Nevertheless, wetland vegetation is sporadically and intermittently present in and along these waterways. Toe drains and ATTACHMENT D 1180
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San Joaquin County, CA Affected Environment and Environmental Consequences agricultural ditches are dominated by a mix of native and nonnative aquatic and semi-aquatic plant species such as curly dock, African pricklegrass, floating water primrose, willow weed, annual beard grass and nutsedge (AECOM, 2011).
The Draft EIS/EIR for the RD 17 Early Implementation Project (AECOM, 2011) documents the presence of a freshwater marsh in a depression on the landside of the levee between Howard Road to the north and a dirt farm road on the south. Vegetation in the marsh is reported as being dominated by narrow-leaved cattail with Fremont cottonwood and red willow trees growing on the perimeter. The draft EIS/EIR also documents a limited amount of freshwater marsh around the edges of a constructed pond that is located on a large private estate and equestrian center east of the levee in RD 17. A second area of freshwater marsh is located just in RD 17 in an area of backwater on the SJR.
Channel Islands
These unique islands are present in the main channels in Fourteenmile Slough and in the Lower Calaveras River. Wetland vegetation is likely to be present around the edges of these islands.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Wetlands and other waters of the U.S. were identified using USGS topographic maps, Google Earth ProTM, the NWI, online mapping layers and the San Joaquin County Multi-Species Habitat Conservation Plan (2000). The NWI was established by USFWS to conduct a nationwide inventory of wetlands. In general, NWI maps are drawn using USGS soil surveys, aerial photo analysis of vegetation patterns, visible hydrology and geographic position to provide an overview of wetlands within an area. Any wetland delineated by an NRCS office is also included on the NWI maps. Prior to project construction, field surveys would be conducted to identify and verify through a formal wetlands delineation their jurisdictional status under the CWA, Section 404.
Impact assessment for these wetlands and waters of the U.S. is based on determining where the project footprint, including the construction and operations footprints, directly or indirectly impacts wetlands and other Waters of the U.S. Potential impacts to emergent wetlands may be underestimated based upon the use of remote sensing tools rather than field evaluation. During later project phases, full field protocols will be used to identify and evaluate project impacts on all wetlands and other waters of the U.S.
USACE administers regulations under Section 404(b)(1) of the CWA, which establishes a program to regulate the discharge of dredged and fill material into waters of the U.S., including wetlands. A draft 404(b)(1) evaluation was prepared (Environmental Addendum), which analyzed the alternatives and has demonstrated the avoidance of wetland impacts to the maximum extent practicable, the minimization of potential impacts and if determined necessary, compensatory mitigation for any unavoidable impacts.
During the project design phase, additional refinements could further reduce impacts.
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San Joaquin County, CA Affected Environment and Environmental Consequences Basis of Significance
A project alternative would have a significant impact on waters of the U.S., including wetlands, if the following significance criteria are met:
Substantial adverse effect on Federally protected wetlands as defined by Section 404 of the CWA (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption or other means.
Substantial adverse effect on Federally protected waters of the U.S., through direct removal, filling, hydrological interruption or other means.
Conflict with the provisions of an adopted habitat conservation plan, natural community’s conservation plan or other approved local, regional or State habitat conservation plan.
While acknowledging the potential consequences of continued elevated flood risk, this impact analysis evaluates the potential impacts of the 6 action alternatives in relation to continuation of current conditions and O&M practices that reasonably would be expected to occur if the project were not implemented based on current approved and funded plans.
ALTERNATIVE 1 - NO ACTION
For the purpose of this environmental impact analysis, the No Action Alternative, assumes that no construction activities or levee vegetation removal beyond routine maintenance would occur in the near term. Routine levee, vegetation and channel maintenance would continue and be conducted consistent with all applicable laws, regulations and other requirements. Old Mormon Slough would continue to convey local stormwater runoff from adjacent lands but would not convey floodflows from the Stockton Diverting Canal and Mormon Slough.
The current level of risk would remain for a levee failure and flooding within the project area. Flooding of urban and agricultural lands would likely result in pollution of the SJR and downstream sloughs and contribute to temporary and long-term water quality degradation. Flooding could inundate urban areas, exposing them to petroleum products, solvents, pesticides, nutrients, soils and other pollutants. These materials could be transported onto adjacent agricultural lands and into waterways. Where flooding occurs on agricultural lands, runoff of pesticides, soils and nutrients into natural areas would be expected. Polluted flood flows would either return to the SJR via overland flow or be collected by drainage systems and discharged to the SJR. Flooding could also transport a wide variety of materials from the adjacent lands and deposit them into waters of the U.S. These could be trees and shrubs, cars, fences and other items commonly found in urban areas.
Depending on the location and magnitude of a flood event, damage to structures and facilities could be localized or more widespread and could require minor to extensive repairs and cleanup. Construction activities related to cleanup could potentially introduce contaminants from stormwater runoff and erosion, which could temporarily impair the receiving water. In addition, emergency repairs would likely require placement of fill into open water and wetlands in order to stabilize or reconstruct levees in the area. All of these effects would be considered significant, because they could result in substantial adverse effects on Federally-protected waters of the U.S. or CWA Section 404 wetlands through filling, including introduction of contaminants. The magnitude of the impacts would depend upon the location of the levee breach, severity of the storm and river flows at the time of flooding. Predicting these events and providing a determination of significance is not possible based on the information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 7A
Levee height fixes and slope reshaping measures proposed under Alternative 7a would impact waters of the U.S., including wetlands, in north and central Stockton. Impacts to waters of the U.S. are summarized in Table 5-4. Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas. Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands. There would be no impacts to waters of the U.S. from cutoff walls and the seismic remediation measures.
Table 5-4: Impacts to Waters of the U.S.
Location Feature Habitat Type
Total
Permanent
Impacts
Total
Temporary
Impacts
Fourteenmile
Slough
Closure Structure Tidally influenced estuary
slough
0.5 acres1 1 acre1
Smith Canal Closure Structure Tidally influenced riverine canal
0.5 acres1 3 acres1
Mosher
Slough
Levee Reshaping,
Vegetation ETL
Waterside wetlands 3 acres 0
Delta Front Levee Reshaping,
Vegetation ETL
Waterside wetlands 4 acres 0
Calaveras
River
Levee Reshaping,
Vegetation ETL
Waterside wetlands 1.75 acres 0
Duck Creek New Levee Waterside wetlands 2 acres 0
Landside Toe
Drains and
Ditches
Seepage berms, levee
height fixes, levee
reshaping
Open water, freshwater marsh
and riparian shrub scrub in
some locations.
N/A Up to 40
acres
TOTAL IMPACT 1 acre up to 44
acres 1 Toe drains and ditches would be reestablished landward of the levee construction.
Levee Height Fixes and Slope Reshaping
Levee improvements would affect waterside wetlands where slope reshaping is required, as estimated in Table 5-4 above. Levee height fixes and slope reshaping may require relocation of the landward levee toe drain. These toe drains would be reestablished landward of the improved levee toe and would continue to function as it had prior to constructing the levee improvements.
Closure Structures
Two flood gates are proposed under Alternative 7a. These gates would be constructed in waters of the U.S.
One gate would be constructed across Fourteenmile Slough and the other across Smith Canal. Closure structure construction is described in Section 4.3.10 and operation is described in Section 4.5.5. The new permanent closure structures would directly and permanently affect 0.5 acres of open water in Fourteenmile Slough and 0.5 acres in Smith Canal. Construction would directly and temporarily impact an additional 1 acre of open water in Fourteenmile Slough and 3 acres of open water in Smith Canal. Table 5-4 shows the acres of waters that would be affected by the in-water closure structures in north and central Stockton under all of the action alternatives, including Alternative 7a.
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San Joaquin County, CA Affected Environment and Environmental Consequences Vegetation ETL
Wetlands that may occur within or immediately adjacent to, the VFZ could be adversely affected by project implementation without a vegetation variance. If a vegetation variance is granted, it is estimated that approximately 25 percent of waterside vegetation would be allowed to remain in place on the lower 1/3 of the levee slope and within the waterside easement. Landside tree and shrub removal would directly or indirectly impact wetlands where equipment or personnel enter wetlands or alter drainage supporting those wetlands. Removal of trees and shrubs could impact wetlands by altering the character of the surrounding vegetation.
Borrow Areas
To construct Alternative 7a, 1,406,000 cy of material would be needed. Although specific borrow locations have not yet been identified, suitable material is available within 25 miles of the project. An estimated 190 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
Based on this evaluation, implementing Alternative 7a would result in short- and long-term effects on waters, including wetlands, as a result of construction and operation of the 2 in-water closure structures.
Construction would affect vegetation and aquatic organisms within the construction footprint and the structure would remain a permanent feature. Hydrodynamic modeling completed recently indicates that the closure structures would slightly alter local water circulation on a recurring basis (See Section 5.5). This change and the presence of the structure itself would potentially affect aquatic organisms in the vicinity.
This alternative would also include temporary impacts associated with fill and relocation of landside toe drains and irrigation ditches. Therefore, project impacts on Federally protected waters would be significant.
Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
ALTERNATIVE 7B
Improvements to the FRM system that are proposed under Alternative 7b would affect waters of the U.S., including wetlands, in north and central Stockton and in RD 17. Impacts to open waters are summarized in Table 5-4. Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas. Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands.
Levee Height Fixes and Slope Reshaping
Under Alternative 7b, impacts from levee height fixes and slope reshaping in north and central Stockton would be the same as described under Alternative 7a. Alternative 7b also includes height fixes and slope reshaping along the northern, western and southern levees around RD 17. These improvements could affect waterside wetlands where slope reshaping is required. Levee height fixes and slope reshaping may require relocation of the landside levee toe drains that would affect wetlands in and adjacent to the toe drains. These toe drains would be reestablished landward of the improved levee toe and would continue to function as it had prior to constructing the levee improvements.
Seismic Remediation
Impacts associated with constructing seismic remediation in north and central Stockton are the same as those described for Alternative 7a. Seismic remediation would not require work in waters of the U.S.
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San Joaquin County, CA Affected Environment and Environmental Consequences Closure Structures
Impacts associated with construction and operation of the closure structures on Fourteenmile Slough and Smith Canal are the same as those for Alternative 7a.
Vegetation ETL
Impacts to wetlands and other waters of the U.S. that could result from vegetation clearing to comply with the Vegetation ETL are the same as those described for Alternative 7a, except that impacts under Alternative 7b would extend along the north, west and southern part of RD 17.
New Levees
Alternative 7b includes construction of two new levee segments. One would be a dry land levee connecting two leveed arms of a meander along the SJR and one would be a dry land levee in the southern portion of RD 17. Construction of these segments would require relocation of local drainage and irrigation ditches affecting wetlands and other waters in and adjacent to these drainages. These ditches would be reestablished landward of the new levees and continue to function as they had prior to construction of the new levee segments.
Seepage Berms
Seepage berms would be constructed landward of levee segments in RD 17. Construction would require relocation of some landside toe drains and local drainage and irrigation ditches affecting wetlands and other waters of the U.S. in and adjacent to these drainages. These drains and ditches would be reestablished landward of the seepage berms and continue to function as they had prior to construction. If emergent wetlands are present within the construction footprint, they would be filled by construction of the seepage berms.
Borrow Areas
To construct Alternative 7b, 3,869,000 cy of material would be needed. Although specific borrow locations have not been identified, suitable material is available in sufficient quantities within 25 miles of the project.
An estimated 385 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
Based on this evaluation, implementing Alternative 7b would result in potentially short- and long-term effects on waters, including wetlands, as a result of construction and operation of the 2 in-water closure structures in Fourteenmile and Tenmile Sloughs, which would permanently change the structure of these sloughs, slightly alter local water circulation, eliminate existing vegetation and sessile and slow moving organisms within the construction footprint and establish the structures as permanent features of Smith Canal and Fourteenmile Slough. In addition, the project would have temporary impacts associated with fill and relocation of landside toe drains and irrigation ditches. In comparison with Alternative 7a, implementing Alternative 7b would result in additional wetlands impacts associated with levee improvements and new levees in RD 17. Impacts on Federally protected waters would be significant.
Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 8A
Improvements to the FRM system that are proposed under Alternative 8a would affect waters of the U.S., including wetlands, in north and central Stockton. Impacts to open waters are summarized in Table 5-4.
Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas.
Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands.
Levee Height Fixes and Slope Reshaping
Under Alternative 8a, impacts from levee height fixes and slope reshaping would be the same as those for Alternative 7a, except that they would extend farther upstream on the lower Calaveras River and on the Stockton Diverting Canal west levee. The effects on waterside wetlands, landside toe drains and ditches would be the same as those for Alternative 7b.
Seismic Remediation
Impacts associated with construction of the seismic remediation are the same as those for Alternative 7a.
Seismic remediation would not require work in waters of the U.S.
Closure Structures
Impacts associated with construction and operation of the closure structures on Fourteenmile Slough and Smith Canal are described under Alternative 7a. There would be no impacts beyond those described.
Vegetation ETL
Potential impacts to wetlands and other waters of the United States that could result from vegetation clearing to comply with the Vegetation ETL are the same as those for Alternative 7a. The impacts under Alternative 8a would also extend farther upstream on the Lower Calaveras River and the Stockton Diverting Canal.
Woody vegetation in these additional areas is relatively sparse.
Borrow Areas
To construct Alternative 8a, 1,807,000 cy of material would be needed. Although specific borrow locations have not yet been identified, suitable material is available in sufficient quantities within 25 miles of the project. An estimated 266 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
Based on this evaluation, implementing Alternative 8a would result in short- and long-term effects on waters of the U.S., including wetlands, as a result of construction and operation of the 2 in-water closure structures on Fourteenmile and Tenmile Sloughs, which would permanently change the structure of these sloughs, slightly alter local water circulation and eliminate existing vegetation and sessile and slow moving organisms in the construction footprint of the closure structures. In addition, the project would have temporary impacts associated with the fill and relocation of landside toe drains and irrigation ditches.
Implementing Alternative 8a would result in greater wetlands impacts than Alternative 7a due to levee improvements along upstream reaches of the lower Calaveras River and the Stockton Diverting Canal.
Alternative 8a would result in significant impacts on Federally protected waters. Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 8B
Improvements to the FRM system that are proposed under Alternative 8b would affect waters of the U.S., including wetlands, in north and central Stockton and in RD 17. Impacts to open waters are summarized in Table 5-4. Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas. Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands.
Levee Height Fixes and Slope Reshaping
Under Alternative 8b, impacts from levee height fixes and slope reshaping would be the same as those for Alternative 7a, except that they would extend farther upstream on the lower Calaveras River and on the Stockton Diverting Canal west levee. Alternative 8b includes the same levee height fixes and slope reshaping in RD 17 as for Alternative 7b. Therefore, the effects on waterside wetlands, landside toe drains and ditches would be the same as those for Alternative 7b.
Seismic Remediation
Impacts associated with construction of the seismic remediation are the same as those for Alternative 7a.
Seismic remediation would not require work in waters of the U.S.
Closure Structures
Impacts associated with construction and operation of the closure structures on Fourteenmile Slough and Smith Canal are the same as those for Alternative 7a.
Vegetation ETL
Potential impacts to wetlands and other waters of the U.S. under Alternative 8b that could result from vegetation clearing, in order to comply with the Vegetation ETL, are the same as those for Alternative 7a.
Additional impacts to wetlands and waters of the U.S. under Alternative 8b would result from construction of the flood bypass through Old Mormon Slough.
Borrow Areas
To construct Alternative 8b, 4,270,000 cy of material would be needed. Although specific borrow locations have not yet been identified, suitable material is available in sufficient quantities within 25 miles of the project. An estimated 458 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
Based on this evaluation, implementing Alternative 8b would result in short- and long-term effects on waters of the U.S., including wetlands, as a result of construction and operation of the 2 in-water closure structures on Fourteenmile and Tenmile Sloughs, which would permanently change the structure of these sloughs, slightly alter local water circulation and eliminate existing vegetation and sessile and slow moving organisms in the construction footprint. In addition there would be temporary impacts associated with fill and relocation of landside toe drains and irrigation ditches. In comparison with Alternative 7a, implementing Alternative 8b would result in additional wetlands impacts associated with levee improvements upstream on the lower Calaveras River and the Stockton Diverting Canal and on levee improvements and new levees in RD 17. Alternative 8b would result in significant impacts to Federally protected waters. Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 9A
Improvements to the FRM system that are proposed under Alternative 9a would affect waters of the U.S., including wetlands, in north and central Stockton. Impacts to open waters are summarized in Table 5-4.
Alternative 9a would affect the length of Old Mormon Slough by constructing a flood bypass from the Stockton Diverting Canal through Old Mormon Slough to the Stockton Deep Water Ship Channel.
Temporary construction impacts to Old Mormon Slough would be mitigated through BMPs and onsite compensatory mitigation, as appropriate. Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas. Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands.
Levee Height Fixes and Slope Reshaping
Under Alternative 9a, impacts from levee height fixes and slope reshaping would be the same as those for Alternative 7a. There would be no impacts beyond those described.
Seismic Remediation
Impacts associated with construction of the seismic remediation are the same as those for Alternative 7a.
Seismic remediation would not require in-water work.
Closure Structures
Under Alternative 9a, impacts associated with construction and operation of the closure structures on Fourteenmile Slough and Smith Canal are the same as those for Alternative 7a. There would be no impacts beyond those described.
Old Mormon Channel Flood Bypass and Diversion Structure Under Alternative 9a, a diversion structure would be constructed through the Stockton Diverting Canal west levee at Old Mormon Slough and a flood bypass would be established through 6.3 miles of the Old Mormon Slough. Portions of Mormon Channel flood bypass would be excavated and graded to assure unimpeded flow conveyance. Three low-water road crossings would be removed and replaced with 3 bridges over the channel. Every 2 years, 1,200 cfs of flood flows would be conveyed through the Mormon Channel. Construction of these structures would result in short- and long-term impacts resulting from fill entering wetlands and waters of the U.S.
Vegetation ETL
Potential impacts to wetlands and other waters of the U.S. that could result from vegetation clearing to comply with the Vegetation ETL are the same as those for Alternative 7a and would result in the same impacts. However, Alternative 9a would result in additional impacts from construction of the flood bypass through Old Mormon Slough.
Borrow Areas
To construct Alternative 9a, 1,406,000 cy of material would be needed. Although specific borrow locations have not yet been identified, suitable material is available in sufficient quantities within 25 miles of the project. An estimated 190 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
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San Joaquin County, CA Affected Environment and Environmental Consequences Based on this evaluation, implementing Alternative 9a would result in short- and long-term effects on waters of the U.S., including wetlands, as a result of construction and operation of the 2 in-water closure structures on Fourteenmile and Tenmile Sloughs, which would permanently change the structure of these sloughs, alter local water circulation and eliminate existing vegetation and sessile and slow moving organisms in the footprint of the closures structures. Alternative 9a would directly affect the channel and potential wetlands through excavation, grading and rewatering the channel with 1,200 cfs of floodflows every 2 years. In addition, Alternative 9a would result in fill and relocation of landside toe drains affecting wetlands. Alternative 9a would result in additional impacts resulting from levee improvements further upstream on the lower Calaveras River and on the Stockton Diverting Canal and from construction of a flood bypass through Old Mormon Slough. Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
ALTERNATIVE 9B
Improvements to the FRM system proposed under Alternative 9b would affect waters of the U.S., including wetlands, in north and central Stockton and in RD 17. Impacts to open waters are summarized in Table 5-4.
Alternative 9a would affect the length of Old Mormon Slough by construction of a flood bypass from the Stockton Diverting Canal through Mormon Channel to the Stockton Deep Water Ship Channel. Temporary construction impacts to Old Mormon Slough would be mitigated through BMPs and onsite compensatory mitigation, as appropriate. Emergent wetland vegetation is present in narrow bands along the banks adjacent to these open water areas. Field surveys would be conducted during PED to specifically identify, quantify and determine the quality of these wetlands.
Levee Height Fixes and Slope Reshaping
Under Alternative 9b, impacts from levee height fixes and slope reshaping would be the same as those for Alternative 7a. Alternative 9b includes levee height fixes and slope reshaping along the northern, western and southern levees around RD 17, which could affect waterside wetlands where slope reshaping is required. Levee height fixes and slope reshaping may require relocation of the landward levee toe drain affecting wetlands in or adjacent to, the levees. These toe drains would be reestablished landward of the improved levee toe and would continue to function as it had prior to constructing the levee improvements.
Seismic Remediation
Impacts associated with construction of the seismic remediation are the same as for Alternative 7a. Seismic remediation would not require work in waters of the U.S.
Closure Structures
Impacts associated with construction and operation of the closure structures on Fourteenmile Slough and Smith Canal are the same as those for Alternative 7a.
Old Mormon Channel Flood Bypass and Diversion Structure Under Alternative 9b a diversion structure would be constructed through the Stockton Diverting Canal west levee at Old Mormon Slough and a flood bypass (Mormon Channel) would be established through 6.3 miles of the Old Mormon Slough. Portions of Mormon Channel would be excavated and graded to assure unimpeded flow conveyance. Three low water road crossings would be removed and replaced with 3 bridges over the channel. Every 2 years, 1,200 cfs of flood flows would be conveyed through the Mormon Channel. Construction of these structures would result in short- and long-term effects from filling of wetlands and waters of the U.S.
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San Joaquin County, CA Affected Environment and Environmental Consequences Vegetation ETL
Potential impacts to wetlands and other waters of the U.S. that could result from vegetation clearing to comply with the Vegetation ETL are the same as those for Alternative 7a, except that impacts from would extend into RD 17.
Borrow Areas
To construct Alternative 9b, 3,869,000 cy of material would be needed. Although specific borrow locations were not identified, suitable material is available in sufficient quantities within 25 miles of the project. An estimated 385 acres would be needed to meet the borrow requirements. Creeks, ditches and wetlands in the vicinity of potential borrow materials would be avoided.
Based on this evaluation, Alternative 9b would result in short- and long-term effects on waters of the U.S., including wetlands, as a result of construction and operation of the 2 in-water closure structures on Fourteenmile and Tenmile Sloughs. These project features would permanently change the structure of Fourteenmile and Tenmile Sloughs and Smith Canal, alter local water circulation and eliminate existing vegetation and sessile and slow moving organisms from the footprint of the closure structures. Alternative 9b would construct and operate a new flood bypass (Mormon Channel) through Old Mormon Slough that would directly affect the channel and potential wetlands through excavation, grading and rewatering the channel with 1,200 cfs of floodflows every 2 years. Alternative 9b would result in temporary impacts associated with fill and relocation of landside toe drains and irrigation ditches, in additional wetlands impacts associated with levee improvements and new levees in RD 17 and construction of a flood bypass through Old Mormon Slough. Implementation of mitigation would reduce impacts to wetlands and waters of the U.S.; however, impacts would remain significant and unavoidable.
MITIGATION
Before construction, a qualified biologist would survey the project area and all wetlands and other waters of the U.S. would be subject to a formal jurisdictional determination and delineation to determine the extent and value of the wetlands affected. All delineated areas would be clearly marked and, to the extent feasible, avoided. Impacts would be minimized by establishing a buffer around wetlands and waterways.
Construction worker awareness training would be conducted to ensure that personnel working the site know the location of and protocols for, working around sensitive habitat. Toe drains and local irrigation and drainage ditches would be relocated and restored with similar wetland habitat functions.
Compensation for permanent impacts to wetland and open water habitats would include the purchase of credits from an approved mitigation bank. The USACE is proposing to purchase 2 acres of bank credits for permanent impacts to open water habitat and 21.5 acres of bank credits for permanent impacts to wetland habitats. In addition, relocated landside levee toe drains and drainage ditches would be restored following construction to their pre-project condition.
Even with implementation of mitigation measures, including avoidance, minimization, restoration and compensatory mitigation, impacts from implementing each action alternative would remain significant and unavoidable due to the effects of construction and operation of the 2 in-water closure structures, which would permanently alter local water circulation and affect aquatic organisms.
AIR QUALITY AND GREENHOUSE GAS EMISSIONS
The following air quality and GHG emissions sections each include an environmental and regulatory setting section.
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San Joaquin County, CA Affected Environment and Environmental Consequences
ENVIRONMENTAL SETTING
Regulatory Framework
Air Quality
Air quality management and protection are regulated by Federal, State and local levels of government. The primary statutes that establish ambient air quality standards and authorities to enforce regulatory attainment are the Federal CAA and California CAA.
Federal
The Federal 1970 CAA authorized the establishment of National health-based air quality standards and set deadlines for their attainment. The Federal Clean Air Act Amendments of 1990 (1990 CAAA) made major changes in deadlines for attaining National Ambient Air Quality Standards (NAAQS) and in the actions required of areas of the Nation that exceeded these standards. Under the CAA, State and local agencies in areas that exceed NAAQS are required to develop State Implementation Plans (SIPs) to show how they will achieve NAAQS for nonattainment criteria pollutants by specific dates. SIPs are not single documents; rather, they are a compilation of new and previously submitted plans, programs (such as monitoring, modeling, permitting, etc.), district rules, State regulations and Federal controls. USEPA is responsible for enforcing NAAQS primarily through reviewing SIPs.
As required by the CAA, USEPA updates NAAQS for criteria air pollutants: ozone, CO, NO2, SO2, PM10, PM2.5 and lead (Pb). NAAQS for these pollutants are listed under “National Standards” in Table 5-5. They represent the upper bound pollutant concentrations deemed necessary by USEPA to protect the public health and welfare with an adequate margin of safety. Ozone is a secondary pollutant that is not emitted directly to the atmosphere. Instead, it forms by the reaction of ROG and NOx in the presence of sunlight and high temperatures. The sources of these pollutants, their effects on human health and the nation's welfare and their annual emission to the atmosphere, vary considerably.
Table 5-6 summarizes SJVAB attainment status with respect to the Federal and State ambient air quality standards. SJVAB is designated as an “extreme” nonattainment area for ozone NAAQS (for the 2008 8- hour ozone standard) and as nonattainment for PM2.5 NAAQS. SJVAB is a designated maintenance area for the CO NAAQS (CARB, 2013b).
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-5: State and National Criteria Air Pollutant Standards, Effects and Sources Pollutant
Averaging
Time
State
Standard
National
Standard
Pollutant Health and
Atmospheric Effects Major Pollutant Sources
Ozone 1 hour 0.09 ppm --- High concentrations can directly affect lungs, causing irritation.
Long term exposure may cause
damage to lung tissue.
Formed when reactive organic
gases (ROG) and nitrogen oxides
(NOx) react in the presence of
sunlight. Major sources include onroad motor vehicles, solvent evaporation and commercial /
industrial mobile equipment.
8 hours 0.07 ppm 0.075 ppm
Carbon
Monoxide
1 hour 20 ppm 35 ppm Classified as a chemical
asphyxiant, carbon monoxide
interferes with the transfer of fresh
oxygen to the blood and deprives
sensitive tissues of oxygen.
Internal combustion engines,
primarily gasoline-powered motor
vehicles. 8 hours 9.0 ppm 9 ppm
Nitrogen
Dioxide
1 hour 0.18 ppm 100 ppb Irritating to eyes and respiratory tract. Colors atmosphere reddishbrown.
Motor vehicles, petroleum refining
operations, industrial sources,
aircraft, ships and railroads. Annual
Avg.
0.030 ppm 0.053 ppm
Sulfur
Dioxide
1 hour 0.25 ppm 75 ppb Irritates upper respiratory tract; injurious to lung tissue. Can yellow
the leaves of plants, destructive to
marble, iron and steel. Limits
visibility and reduces sunlight.
Fuel combustion, chemical plants,
sulfur recovery plants and metal
processing. 3 hours --- 0.5 ppm
24 hours 0.04 ppm 0.14 ppm
Annual
Avg.
--- 0.030 ppm
Respirable
Particulate
Matter
(PM10)
24 hours 50 ug/m3 150 ug/m3 May irritate eyes and respiratory tract, decreases in lung capacity,
cancer and increased mortality.
Produces haze and limits visibility.
Dust and fume-producing
industrial and agricultural
operations, combustion,
atmospheric photochemical
reactions and natural activities
(e.g., wind-raised dust and ocean
sprays).
Annual
Avg.
20 ug/m3 ---
Fine
Particulate
Matter
(PM2.5)
24 hours --- 35 ug/m3 Increases respiratory disease, lung damage, cancer and premature
death. Reduces visibility and
results in surface soiling.
Fuel combustion in motor vehicles,
equipment and industrial sources;
residential and agricultural
burning; Also, formed from
photochemical reactions of other
pollutants, including NOx, sulfur
oxides and organics.
Annual
Avg.
12 ug/m3 12 ug/m3
Lead Monthly
Ave.
1.5 ug/m3 --- Disturbs gastrointestinal system
and causes anemia, kidney disease
and neuromuscular and
neurological dysfunction.
Present source: lead smelters,
battery manufacturing & recycling
facilities. Past source: combustion
of leaded gasoline. Quarterly --- 1.5 ug/m3
Hydrogen
Sulfide
1 hour 0.03 ppm No
National
Standard
Nuisance odor (rotten egg smell),
headache and breathing difficulties
(higher concentrations)
Geothermal Power Plants,
Petroleum Production and refining
Sulfates 24 hour 25 ug/m3 No
National
Standard
Breathing difficulties, aggravates
asthma, reduced visibility
Produced by the reaction in the air
of SO2.
Visibility
Reducing
Particles
8 hour Extinction of
0.23/km;
visibility of
10 miles or
more
No
National
Standard
Reduces visibility, reduced airport
safety, lower real estate value and
discourages tourism.
PM2.5.
ppm = parts per million;ug/m3 = micrograms per cubic meter.
SOURCE: California Air Resources Board, 2013a.; California Air Resources Board, 2009.
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-6: San Joaquin Valley Attainment Status
Pollutant
Designation/Classification
Federal Standards State Standards
Ozone – one hour Nonattainment1 Nonattainment
Ozone – eight hour Nonattainment/Extreme Nonattainment
PM10 Attainment Nonattainment
PM2.5 Nonattainment Nonattainment
CO Unclassified/Attainment Attainment
Nitrogen Dioxide Unclassified/Attainment Attainment
Sulfur Dioxide Unclassified Attainment
Lead Unclassified/Attainment Attainment
Hydrogen Sulfide No Federal Standard Unclassified
Sulfates No Federal Standard Attainment
Visibility Reducing Particles No Federal Standard Unclassified 1 Effective June 15, 2005, the U.S. EPA revoked the Federal 1-hour ozone standard, including associated designations and classifications.
However, the SJVAPCD is mandated by the Federal CAA to develop a plan to meet the revoked standard. In 2013, SJVAPCD recorded no violations of the 1-hour ozone standard.
SOURCE: CARB 2013b.
Pursuant to CAA Section 176(c) requirements, USEPA promulgated the General Conformity Rule, which is used to determine if Federal actions meet the requirements of the CAA and the applicable SIPs by ensuring that pollutant emissions related to the action do not:
Cause or contribute to new violations of a NAAQS.
Increase the frequency or severity of any existing violation of a NAAQS. Delay timely attainment of a NAAQS or interim emission reduction.
A conformity determination under the General Conformity Rule is required if the Federal agency determines that:
The action will occur in a nonattainment or maintenance area, One or more specific exemptions do not apply to the action, The action is not included in the Federal agency’s “presumed to conform” list, The emissions from the project are not within the approved emissions budget for an applicable facility, and
The total direct and indirect emissions of a pollutant (or its precursors) are at or above the de minimis levels established in the General Conformity regulations.
An action will be determined to conform to the applicable SIPs if the action meets the requirements of 40 CFR 93.158(c). The applicable general conformity thresholds that apply to all projects within SJVAPCD are as follows: 10 tons per year for ROG and NOx (ozone precursors), 100 tons per year for directly emitted PM2.5, 100 tons per year for CO and 100 tons per year for SO2 (as a precursor to PM2.5).
State
The California Air Resources Board (CARB) is responsible for the development, implementation and enforcement of California’s motor vehicle pollution control program, administration of the State’s air ATTACHMENT D 1193
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San Joaquin County, CA Affected Environment and Environmental Consequences pollution research program, adoption and updating, as necessary, of CAAQS, review of local APCD activities and coordination of the development of the SIPs for achievement of the NAAQS.
CCAA establishes an air quality management process that generally parallels the Federal process. CCAA, however, focuses on attainment of CAAQS that, for certain pollutants and averaging periods, are more stringent than NAAQS. CAAQS are included in Table 5-5 along with NAAQS. Table 5-6 shows that the SJVAB, including San Joaquin County, are classified as nonattainment for the ozone, PM10 and PM2.5 CAAQS.
CCAA requires that air districts prepare a clean air plan or air quality attainment plan if the district violates CAAQS for CO, SO2, NO2 or ozone, showing strategies for and progress toward attaining CAAQS. These plans are updated triennially.
CCAA requires that CAAQS be met as expeditiously as practicable, but does not set precise attainment deadlines. Instead, the act established increasingly stringent requirements for areas that will require more time to achieve standards. The air quality attainment plan requirements established by CCAA are based on the severity of air pollution problems caused by locally generated emissions. Upwind air pollution control districts are required to establish and implement emission control programs commensurate with the extent of pollutant transported to downwind districts. Air pollution problems in SJVAB are primarily the result of locally generated emissions. However, air pollution occasionally includes contributions from the San Francisco Bay Area or the Sacramento Valley.
Local
SJVAPCD is responsible for implementing Federal and State regulations at the local level, permitting stationary sources of air pollution and developing the local elements of SIPs. Emissions from indirect sources, such as automobile traffic associated with development projects, are addressed through APCD’s air quality plans, which are each air quality district’s contribution to the SIPs.
In addition, air quality management at the local level is also accomplished through SJVAPCD imposition of mitigation measures on project EIRs and mitigated negative declarations developed by project proponents under CEQA. Specific to project construction emissions, CEQA requires mitigation of air quality impacts that exceed certain significance thresholds set by the local air district. SJVAPCD’s CEQA significance thresholds, which would be applicable to the project, are described below.
Greenhouse Gas Emissions
Federal
USEPA is responsible for GHG regulation at the Federal level. Key Federal GHG guidance and regulations relevant to the project are:
In Massachusetts v. U.S. Environmental Protection Agency, et al., 127 Sc.D. 1438 (2007), the U.S. Supreme Court ruled that GHGs fit within CAA’s definition of a pollutant and that USEPA has the authority to regulate GHGs.
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San Joaquin County, CA Affected Environment and Environmental Consequences On December 7, 2009, the Final Endangerment and Cause or Contribute Findings for GHGs (endangerment finding) under Section 202(a) of the CAA, went into effect. The endangerment finding states that current and projected concentrations of the 6 key, well mixed GHGs in the atmosphere [carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and other fluorinated gases including nitrogen trifluoride (NF3) and hydrofluorinated ethers (HFEs) threaten the health and welfare of current and future generations. Furthermore, it states that the combined emissions of these GHGs from new motor vehicles and their engines contribute to GHG pollution that threatens public health and welfare (USEPA 2012a).
Under the endangerment finding, USEPA is developing vehicle emission standards under CAA. USEPA and the Department of Transportation’s National Highway Traffic Safety Administration issued a joint proposal to establish a program that includes standards that will reduce GHG emissions and improve fuel economy for light-duty vehicles in model years 2012 through 2016. This proposal marks the first GHG standards proposed by USEPA under the CAA as a result of the endangerment and cause or contribute findings (USEPA 2012b). These emission reductions were incorporated into the project analysis.
On February 18, 2010, the White House Council on Environmental Quality (CEQ) released draft guidance regarding the consideration of GHGs in NNEPA documents for Federal actions. On December 18, 2014, CEQ released revised draft guidance that describes how Federal departments and agencies should consider the effects of GHGs and climate change in their NEPA reviews. The revised draft guidance supersedes the draft GHG guidance released by CEQ in February 2010 and recommends that agencies consider 25,000 metric tons of carbon dioxide equivalent (CO2e) emissions from a proposed action to trigger a quantitative analysis. The revised draft guidance also emphasizes that agency analyses should be commensurate with projected GHG emissions and climate impacts (White House CEQ, 2014). Revised Draft Guidance for GHG Emissions and Climate Change Impacts. Available at:
https://www.whitehouse.gov/administration/eop/ceq/initiatives/nepa/ghg-guidance.
State
The CARB is responsible for the development, implementation and enforcement of California’s motor vehicle pollution control program, GHG statewide emission estimates and goals, and development and enforcement of GHG emission reduction rules.
California is a substantial contributor of global GHGs as it is the second largest contributor in the U.S. and the sixteenth largest in the world (CEC 2006). From 1990 through 2003, California’s gross State product grew 83 percent, while GHG emissions grew 12 percent. While California has a high amount of GHG emissions, it has low emissions per capita. The major source of GHG in California is transportation, contributing 41 percent of the State’s total GHG emissions (CEC 2006). Electricity generation is the second largest generator, contributing 22 percent of the State’s GHG emissions. Emissions from fuel use in the commercial and residential sectors decreased 9.7 percent over the 1990 to 2004 period (CEC 2006).
California has taken proactive steps, briefly described in Table 5-7, to address the issues associated with GHG emissions and climate change.
California Environmental Quality Act GHG Amendments
CEQA and its Guidelines require that State and local agencies identify significant environmental impacts of their actions and to avoid or mitigate potentially significant impacts, when feasible. The CEQA amendments of December 30, 2009, specifically require lead agencies to address GHG emissions in determining the significance of environmental effects caused by a project and to consider feasible means to mitigate the significant effects of GHG emissions (California Natural Resources Agency 2010).
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San Joaquin County, CA Affected Environment and Environmental Consequences Relevant provisions of CEQA amendments include the following list. A lead agency subject to CEQA may consider the following when assessing the significance of impacts from GHG emissions:
1) The extent to which the project may increase or reduce GHG emissions as compared to the existing environmental setting;
2) Whether the project emissions exceed a threshold of significance that the lead agency determines applies to the project;
3) The extent to which the project complies with regulations or requirements adopted to implement a statewide, regional or local plan for the reduction or mitigation of GHGs.
When an agency makes a statement of overriding considerations, the agency may consider adverse environmental effects in the context of region-wide or statewide environmental benefits. Lead agencies shall consider feasible means of mitigating GHGs that may include, but not be limited to:
1) Measures in an existing plan or mitigation program for the reduction of emissions that are required as part of the lead agency’s decision;
2) Reductions in emissions resulting from a project through implementation of project features, project design or other measures;
3) Off-site measures, including offsets;
4) Measures that sequester GHGs;
5) In the case of the adoption of a plan, such as a general plan, long-range development plan or GHG reduction plan, mitigation may include identification of specific measures that may be implemented on a project-by-project basis. Mitigation may also include the incorporation of specific measures or policies found in an adopted ordinance or regulation that reduces the cumulative effect of emissions.
Local
SJVAPCD is responsible for implementing Federal and State regulations at the local level. SJVAPCD developed guidance that San Joaquin Valley land use agencies can use to address GHG emission impacts for new projects under CEQA.
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-7: Summary of Relevant California GHG Regulations Bill, Year Description
Assembly
Bill (AB)
4420, 1988
Directed California Energy Commission, in consultation with the CARB and other agencies, to “study and report…on how global warming trends may affect California’s energy supply and demand, economy, environment, agriculture and water supplies.” AB 1493,
2002
Requires CARB to develop and implement regulations to reduce automobile and lighttruck GHG emissions. The stricter emissions standards apply to automobiles and light trucks beginning with the 2009 MY. Although litigation was filed challenging these regulations and EPA initially denied California’s related request for a waiver, the waiver request has now been granted.
EO S-3-05,
2005
The goal of EO S-3-05 is to reduce California’s GHG emissions to: (1) year 2000 levels by 2010, (2) 1990 levels by 2020 and (3) 80 percent below the 1990 levels by 2050.
AB 32,
California
Global
Warming
Solutions Act
of 2006
Sets overall GHG emissions reduction goals and mandates that CARB create a plan that includes market mechanisms and implement rules to achieve “real, quantifiable, cost-effective reductions of GHGs.” Requires statewide GHG emissions be reduced to 1990 levels by 2020. (The 1990 CO2e level is 427 million metric tons of CO2e (CARB 2011)). Directs CARB to develop and implement regulations to reduce statewide emissions from stationary sources. Specifies that regulations adopted in response to AB 1493 be used to address GHG emissions from vehicles. Requires CARB to adopt a quantified cap on GHG emissions representing 1990 emissions levels. Includes guidance to institute emissions reductions in an economically efficient manner and conditions to ensure that businesses and consumers are not unfairly affected by the reductions.
EO S-01-07,
2007
Requires the carbon intensity of California’s transportation fuels to be reduced by at least 10 percent by 2020.
Senate Bill
97 This bill directed the Natural Resources Agency, in coordination with the Governor’s Office of Planning Research, to address the issues through Amendments to the CEQA Guidelines. The revised Guidelines were adopted December 30, 2009 to provide direction to lead agencies about evaluating, quantifying and mitigating a project’s potential GHG emissions.
Source: CARB 2012a, CARB 2012b, CARB 2012c
Existing Conditions
Air Quality
The study area for the project is the San Joaquin County portion of the San Joaquin Valley Air Basin (SJVAB), which includes the 8 counties within the San Joaquin Valley.2 SJVAPCD regulates air quality within the SJVAB. Approximately 250 miles long and 35 miles wide, SJVAB is a well-defined climatic region with distinct topographic features on 3 sides. The Coast Ranges, which have an average elevation of 3,000 feet, are located on the western border of SJVAB. The San Emigdio Mountains, which are part of the Coast Ranges and the Transverse Ranges, which are part of the Sierra Nevada, are both located on the south side of SJVAB. The Sierra Nevada forms the eastern border of SJVAB. No topographic feature delineates the northern edge of the basin.
2 The SJVAB includes the following counties: San Joaquin, Stanislaus, Madera, Merced, Tulare, Kings, Fresno and the portion of Kern County west of the crest of the Sierra Nevada Mountains.
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San Joaquin County, CA Affected Environment and Environmental Consequences SJVAB is flat with a downward gradient to the northwest. Air flows into SJVAB through the Carquinez Strait, the only breach in the western mountain barrier, moves across the Delta from the San Francisco Bay area. The mountains surrounding SJVAB create a barrier to airflow that leads to entrapment of air pollutants when meteorological conditions are unfavorable for transport and dilution. As a result, SJVAB is highly susceptible to pollutant accumulation over time.
Summer is considered the ozone season in SJVAB, characterized by poor air movement in the mornings and longer daylight hours. Sunlight fuels photochemical reactions between reactive organic gases (ROG) and nitrogen oxides (NOx), resulting in ozone formation. Summer winds usually originate at the north end of the San Joaquin Valley and flow in a south-southwesterly direction through Tehachapi Pass and into the Southeast Desert Air Basin.
Criteria Pollutants
Criteria pollutants are the 6 air pollutants of primary concern to public health as established by the CAA.
They include ozone, nitrogen dioxide, carbon monoxide (CO), particulate matter, sulfur oxides and lead.
Of these 6, the pollutants of most concern for the project alternatives, which will result primarily from construction activities, are ozone precursors (consisting NOx and ROG), CO and particulate matter (PM10 and PM2.5). Within San Joaquin County, on-road motor vehicles are the major source of ROG, NOx and CO emissions. Other equipment and off-road vehicles contribute substantially to ROG, CO and NOx emissions. Fugitive dust, generated from construction, roadways and farming operations, is the major source of PM10 and, to a lesser degree, PM2.5. Fuel combustion also substantially contributes to PM2.5 emissions.
Table 5-8 shows recent monitoring data for ozone, PM10 and PM2.5. Monitoring data for CO and NO2 are not shown, because there were no recorded violations of either CAAQS or NAAQS during the 2011-2013 period. Based on 2011-2013 data collected at the two monitoring stations located within San Joaquin County, ozone, PM10 and PM2.5 exceeded CAAQS and/or NAAQS.
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-8: Air Quality Monitoring Data for San Joaquin County Toxic Air Contaminants
Toxic Air Contaminants (TAC) are defined by California law as an air pollutant that “may cause or contribute to an increase in mortality or an increase in serious illness or which may pose a present or potential hazard to human health.” USEPA uses the term Hazardous Air Pollutant (HAPs) in a similar manner. Controlling toxic air emissions became a National priority with the passage of the Clean Air Act Amendments, whereby Congress mandated that USEPA regulate 188 air toxics. TACs can be emitted from stationary and mobile sources.
Ten TACs were identified through ambient air quality data as posing the greatest health risk in California.
Direct exposure can cause cancer, birth defects, damage to the brain and nervous systems and respiratory disorders. TACs do not have ambient air quality standards because no safe levels were identified. Instead, TAC impacts are evaluated by calculating the health risks associated with a given exposure.
Criteria Air Pollutant NAAQS CAAQS Yearly Monitoring Data 2011 2012 2013
Stockton – Hazelton Street
Ozone – 8-hour 0.075 ppm 0.07 ppm
Highest concentration (ppm) 0.068 0.083 0.067
Days above CAAQS 0 6 0
Days above NAAQS 0 2 0
Tracy – Airport
Ozone – 8-hour 0.075 ppm 0.07 ppm
Highest concentration (ppm) 0.087 0.098 0.082
Days above CAAQS 21 36 5
Days above NAAQS 8 16 2
PM10 – Hazelton Street
Highest 24-hour (µg/m3) 150 µg/m3 50 µg/m3 70.1 70.0 95.5 Annual Arithmetic mean (µg/m3) N/A 20 µg/m3 24.1 22.8 32.0 Days above CAAQS 24.4 17.9 58.2
Days above NAAQS 0.0 0.0 0.0
PM10 – Tracy Airport
Highest 24-hour (µg/m3) 150 µg/m3 50 µg/m3 110.8 73.4 73.2 Annual Arithmetic mean (µg/m3) N/A 20 µg/m3 17.5 21.0 22.6 Days above CAAQS N/A N/A N/A
Days above NAAQS 0.0 0.0 0.0
PM2.5 – Hazelton Street
Highest 24-hour (µg/m3) 35 µg/m3 N/A 60.0 60.4 66.5
Annual Arithmetic mean (µg/m3) 12.0 µg/m3 12 µg/m3 11.3 12.3 17.6 Days above CAAQS N/A N/A N/A
Days above NAAQS 11 6 27.6
Notes:
ppm = parts per million
µg/m3 = micrograms per cubic meter
Source: California Air Resources Board, 2014.
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San Joaquin County, CA Affected Environment and Environmental Consequences The TAC of interest to this project is Diesel Particulate Matter (DPM), primarily because of diesel powered construction equipment. DPM was identified by the California Office of Environmental Health Hazard Assessment (OEHHA) as a carcinogen and as a chronic health risk (California OEHHA, 2013).
Odors
Odors are typically associated with specific types of industrial sources such as wastewater treatment plants, chemical manufacturing, refineries and rendering plants. Odors associated with construction projects such as levee construction and maintenance typically do not constitute significant odor sources.
Sensitive Receptors
Some locations are considered more sensitive to adverse effects from air pollution than others. A sensitive receptor is generally defined as a location where human populations, especially children, seniors and sick persons are found and where there is a reasonable expectation of continuous human exposure according to appropriate standards (e.g., 24-hour, 8-hour and 1-hour). Sensitive land uses and sensitive receptors generally include residents, medical facilities, schools and day care facilities.
Climate Change
Warming of the earth’s climate is now considered to be unequivocal (IPCC, 2007). Global average surface temperature increased approximately 1.33 °F over the last 100 years, with the most severe warming occurring in the most recent decades. In the 12 years between 1995 and 2006, 11 years ranked among the warmest in the record of global average surface temperature (going back to 1850). Continued warming is projected to increase global average temperature between 2 and 11 °F over the next 100 years (IPCC, 2007).
The causes of this are both natural processes and the result of human actions. Increases in GHG concentrations in the Earth’s atmosphere are thought to be the main cause of human induced climate change.
Some GHGs, such as CO2, are emitted to the atmosphere by natural processes and human activities. Other GHGs (e.g., fluorinated gases) are created and emitted solely through human activities. Each GHG traps a different amount of heat. In order to compare emissions of different GHGs, a weighting factor called a Global Warming Potential (GWP) is used. Emissions are expressed in terms of CO2e. Therefore, the GWP of CO2 is 1; the GWP of methane (CH4) is 21; and the GWP of nitrous oxide (N2O) is 310. These 3 GHGs are evaluated for this project, because they would be emitted during construction activities, primarily as a by-product of fuel combustion.
Statewide GHG emissions in 2008 were 427 million metric tons of CO2e. Based on this estimate, statewide emissions would need to be reduced by 16 percent from existing levels to meet the AB 32 goal of achieving 1990 CO2e levels (427 million metric tons of CO2e) (CARB, 2011).
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
This section describes the air quality and GHG significance thresholds, explains the methodology used to evaluate significance.
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San Joaquin County, CA Affected Environment and Environmental Consequences Assessment Methods
Criteria Pollutants
Emissions were calculated using the Road Construction Emission Model (RCEM), used to estimate emissions from linear construction projects. RCEM uses the CARB OFFROAD 2011 and EMFAC2011 emission factors.3 The worksheet estimates emissions for both vehicle exhaust and fugitive dust. The methodology used to estimate fugitive dust emissions involves estimates of the maximum area (acreage) of land disturbed daily.
The RCEM software calculates a project's emissions in pounds per day (and kilograms per day) by project phase and metric tons over the entire construction period.
For each project alternative, emissions were estimated using RCEM for each year of construction and for each phase within each year. The phases included:
1) Grubbing /land clearing,
2) Tree removal,
3) Stripping to spoil
4) Excavation to stockpile
5) Excavation to spoil
6) Cutoff wall conventional
7) Cutoff wall deep soil mixing
8) Cohesive fill
9) Random fill
10) Road – Place and fine grade
11) Revegetation/Seeding
12) Rip/Rap placement
3 RCEM (Road Construction Emissions Model) is used to estimate construction emissions from linear projects such as roadways, bridges, utility work and levee repair (SMAQMD, 2013).
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San Joaquin County, CA Affected Environment and Environmental Consequences The length of each phase and the construction equipment used with each phase was based on information developed by USACE (Elsberry, J., 2014).
Toxic Air Contaminants
Toxic air contaminants were evaluated qualitatively by examining the likelihood that each alternative would cause significant health risks to nearby sensitive receptors.
Odors
Odors were evaluated qualitatively by the likelihood that each alternative would create significant odor impacts to nearby sensitive receptors.
GHG Emissions
Since RCEM estimates CO2 emissions but not CO2e emissions, CO2 emissions estimates were increased by 5 percent to represent total CO2e emissions1
.
Basis of Significance
Air Quality Significance Thresholds
According to CEQA Guidelines, a significant impact would occur with respect to air quality if the project would:
Result in a cumulatively considerable net increase of any criteria air pollutant for which the region is in nonattainment;
Conflict with or obstruct implementation of the applicable air quality plan; Expose sensitive receptors to substantial pollutant concentrations; or Create objectionable odors affecting a substantial number of people.
Criteria Pollutants
Due to the general nature of the 4 significance thresholds listed above, SJVAPCD developed quantitative criteria to evaluate the significance of air emissions under CEQA. Specifically, a significant impact would occur if implementation of a project alternative would result in emissions that exceed thresholds established by SJVAPCD. Thresholds for a project are:
NOx: 10 tons per year
ROG: 10 tons per year
PM10: 15 tons per year
PM2.5: 15 tons per year
SO2: 27 tons per year (SJVAPCD, 2012)
SJVAPCD’s CEQA thresholds represent the emission levels that would result in a direct and/or indirect project impact, as well as impacts resulting in a cumulatively considerable net increase in pollutants.
SJVAPCD applies the CEQA thresholds listed above separately to 3 emission categories: 1) construction emissions, 2) operational non-exempt equipment emissions and 3) operational exempt emissions. 1 CO2e emissions from construction equipment typically are no more than 5 percent greater than CO2 emissions.
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San Joaquin County, CA Affected Environment and Environmental Consequences The second category – operational non-exempt emissions, includes emissions from any operational source subject to stationary source air permitting. The third category – operational exempt emissions – includes emissions from all operational sources that are exempt from stationary source air permitting, including both stationary and mobile sources (SJVAPCD, 2012).
The General Conformity Rule (GCR) requires that the responsible Federal agency review any action to determine if it would be likely to cause or contribute to a violation of NAAQS or delay timely attainment of any NAAQS or any interim emission reduction required by the applicable SIPs or any other Federally identified air quality milestones. The first step in the conformity process is to evaluate whether the action would produce emissions above the GCR de minimis thresholds applicable to the specific area, thus requiring a detailed air quality conformity analysis.
The GCR de minimis levels are based on the nonattainment classification of the local air basin. The project alternatives are located in SJVAB, an ozone nonattainment area classified as “extreme.” SJVAB is also classified as nonattainment for PM2.5 and was recently classified as a maintenance area for PM10. The applicable GCR de minimis thresholds for the project alternatives are:
NOx: 10 tons per year
ROG: 10 tons per year
PM10: 100 tons per year
PM2.5: 100 tons per year
SO2: 100 tons per year (as a precursor to PM2.5)
The GCR de minimis thresholds are applied to combined construction and operational emissions occurring each year. If a project’s combined emissions are below the de minimis levels, the Federal action agency is not required to make a general conformity determination and the action would be considered to conform to the SIPs (40 Code of Federal Regulations [CFR] 93 § 153). The GCR de minimis levels are typically used to determine the potential significance of an impact under NEPA and are used to evaluate significance for this Project.
Toxic Air Contaminants
The project alternatives would emit DPM from heavy-duty trucks and emergency diesel generators. DPM is considered a TAC that can increase both carcinogenic and chronic health risks (California OEHHA, 2013). A project is considered to have a significant TAC impact if it would:
Result in ground level concentrations of carcinogenic TACs that would increase the probability of contracting cancer for the maximally exposed individual by 10 in 1 million or more or; Increase ground level concentrations of non-carcinogenic TACs that would result in a hazard index exceeding 1 for the maximally exposed individual.
The TAC analysis evaluates potential DPM impacts associated with construction and operations. These thresholds are used to evaluate significance for both CEQA and NEPA.
Odors
SJVAPCD’s CEQA guidance defines a significant odor impact as one that:
Creates objectionable odors affecting a substantial number of people.
SJVAPCD’s guidance lists facility types that commonly produce odors and the separation distance from sensitive receptors (typically 1 mile) needed to prevent significant odor impacts (SJVAPCD, 2012). The ATTACHMENT D 1203
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San Joaquin County, CA Affected Environment and Environmental Consequences list of facility types is not meant to be all-inclusive. Consequently, SJVAPCD recommends that all potential odor sources be evaluated in additional detail if they are located within 1 mile of sensitive receptors. This approach is used to evaluate odor impacts for the project alternatives for both CEQA and NEPA.
GHG Significance Thresholds
According to CEQA Guidelines, a significant GHG impact would occur if an action would:
Generate GHG emissions, either directly or indirectly, that may have a significant impact on the environment;
Conflict with an applicable plan, policy or regulation adopted for reducing the emissions of GHGs.
The SJVAPCD recommends a 29 percent reduction in GHG emissions be used to evaluate a project’s CEQA significance. This percentage is based on a project’s actual mitigated emissions when compared to business as usual emissions that do not account for mitigation or rules and regulations enacted to comply with AB 32. SJVAPCD’s approach to estimating percentage reduction was recently invalidated by the California Supreme Court (CBD v. CDFW and Newhall Land and Farming Company, S217763) because it used the statewide average percentage reduction of 29% instead of a percentage calculated specifically for the San Joaquin Valley Air Basin. Consequently, for CEQA, the project’s GHG emissions are evaluated based on consistency with the two CEQA significance guidelines listed above.
Draft NEPA GHG guidance states that emissions greater than the 25,000 metric tons of CO2e2 per year should be the threshold at which GHG emissions are quantified. However, 25,000 metric tons of CO2e is not a significance threshold, it is only the threshold at which GHG emissions are recommended to be quantified (White House Council on Environmental Quality, 2010). For the purposes of this analysis, 25,000 metric tons CO2e per year is used as the significance threshold for NEPA.
Effects and Mitigation Measures
ALTERNATIVE 1 - NO ACTION
Under the No Action Alternative, no construction would occur and no GHG emissions would result. In addition, existing levels of operational GHG emissions from maintenance activities would not change.
However, without added flood control measures, there would be a greater likelihood of future flooding and associated property damage (California DWR, 2012). Consequently, although there would be no direct increase in GHG emissions associated with the No Action Alternative, there would be a higher likelihood of future flooding. The increased probability of future flooding could result in GHG emissions from emergency response to such events and the resulting emissions associated with rebuilding. However, developing accurate scenarios needed to estimate GHG emissions is speculative at best. Therefore, the impact of the No Action Alternative is considered too speculative for meaningful consideration.
ALTERNATIVE 7A
Table 5-9 summarizes Alternative 7a’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 7a would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2023. From 2024 through 2029, the project’s NOx emissions would be less than the respective thresholds. 2 CO2e = carbon dioxide equivalent. CO2e is a metric measure used to compare the emissions from various GHGs based upon their GWP, using carbon dioxide as the reference gas (i.e., GWP of CO2 is 1).
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San Joaquin County, CA Affected Environment and Environmental Consequences Annual emissions decrease over time because construction activity levels drop and the construction fleet generates lower average emissions over time as older equipment generating high levels of emissions is replaced by newer, lower-emitting equipment. Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions during the 2019 through 2023 period would still exceed SJVAPCD significance thresholds and Federal conformity thresholds, and would therefore contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
ALTERNATIVE 7B
Table 5-13 summarizes Alternative 7b’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 7b would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2024. From 2025 through 2031, the project’s NOx emissions would be equal to or less than the respective thresholds. Annual emissions decrease because the construction fleet generates lower emissions over time as older equipment generating high levels of emissions is replaced by newer, lower-emitting equipment.
Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions during the 2019 through 2024 period would still exceed SJVAPCD significance thresholds and Federal conformity thresholds and would therefore contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
ALTERNATIVE 8A
Table 5-17 summarizes Alternative 8a’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 8a would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2024. From 2025 through 2029, the project’s NOx emissions would be less than the respective thresholds.
Annual emissions decrease because the construction fleet generates lower emissions over time as older equipment generating high levels of emissions is replaced by newer, lower-emitting equipment.
Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions during the 2019 through 2024 period would still exceed SJVAPCD significance thresholds and Federal conformity thresholds and would therefore contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
ALTERNATIVE 8B
Table 5-21 summarizes Alternative 8b’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 8b would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2028. From 2029 through 2031, the project’s NOx emissions would be less than the respective thresholds.
Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions from 2019 through 2028 would still exceed SJVAPCD significance thresholds and Federal conformity thresholds and would therefore contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
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San Joaquin County, CA Affected Environment and Environmental Consequences ALTERNATIVE 9A
Table 5-25 summarizes Alternative 9a’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 9a would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2023. From 2024 through 2029, the project’s NOx emissions would be less than the respective thresholds.
Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions during the 2019 through 2023 period would still exceed SJVAPCD significance thresholds and Federal conformity thresholds and would, therefore, contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
ALTERNATIVE 9B
Table 5-29 summarizes Alternative 9b’s construction emissions. Emissions would be below the SJVAPCD and Federal conformity thresholds for all pollutants except NOx. For NOx, Alternative 9b would generate emissions exceeding SJVAPCD’s CEQA thresholds and Federal conformity thresholds from 2019 through 2024. From 2025 through 2031, the project’s NOx emissions would be less than the respective thresholds.
Construction-related NOx emissions would likely be offset by future reductions in NOx emissions resulting from flood avoidance. However, NOx emissions during the 2019 through 2024 period would still exceed SJVAPCD significance thresholds and Federal conformity thresholds and would, therefore, contribute to ozone exceedances in an area designated as an extreme ozone nonattainment area. Consequently, the project’s NOx emissions are significant.
MITIGATION
Alternative 7a Mitigation
The emissions shown in Table 5-9 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The following measures focus on reducing NOx emissions. The Lead Agency shall either:
Require the use of off-road equipment that meets or exceeds USEPA or California Air Resources Board CARB Tier 3 off-road emission standards for all off-road vehicles greater than 25 horsepower and operating for more than 20 total hours over the entire duration of construction activities. Prior to issuance of a construction permit, the prime contractor(s) shall prepare and submit a Construction Emissions Minimization Plan (Plan) to the Lead Agency for review and approval. The Plan shall include estimates of the construction timeline by phase with a description of each piece of equipment required for every construction phase. Equipment descriptions and information shall include: equipment type, equipment manufacturer, equipment identification number, engine model year, engine certification (Tier rating), horsepower, engine serial number and expected fuel usage and hours of operation. The Plan shall be kept by the Lead Agency and made available for review by any persons requesting it. Quarterly reports shall be submitted by the prime contractor(s) to the Lead Agency indicating the construction phase and equipment information used during each phase for the previous quarter; or
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San Joaquin County, CA Affected Environment and Environmental Consequences Enter into a Verified Emission Reduction Agreement (VERA) with SJVAPCD. The VERA would require payment of a fee to SJVAPCD that would be used to purchase NOx emission reductions to offset all NOx emissions during years when the Project’s unmitigated NOx emissions exceed 10 tons. The VERA will be entered into prior to initiating the project and posted on the Lead Agency’s website. The NOx offsets developed by the fee will be provided to the Lead Agency and posted on the Lead Agency’s website. The information shall be posted in a location that is easy to access by the public and must remain on the website for 1 full year after all construction is completed.
Implementation of either measure listed above will reduce NOx emissions during construction. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5.
However, those emission reductions are not shown in Table 5-10, because the unmitigated emissions of these other pollutants (Table 5-9) are below State and Federal significance thresholds.
Table 5-9: Alternative 7a Annual Construction Emissions Calendar Year
ROG
(tons/ yr)
CO
(tons/yr)
NOx (tons/
yr)
SO2
(tons/yr)
PM10
(tons/yr)
PM2.5
(tons/ yr)
CO2e
(metric
tons/yr)
2019 1.3 8.8 17.7 0.3 6.7 1.9 3,661
2020 1.2 .8 15.3 0.3 6.7 1.8 3,614
2021 1.1 8.9 12.0 0.3 6.6 1.8 3,606
2022 1.7 16.5 14.6 0.3 5.7 1.7 5,132
2023 1.4 14.1 11.6 0.3 5.4 1.5 3,535
2024 0.7 8.2 5.3 0.2 4.7 1.1 1,759
2025 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2026 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2027 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2028 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2029 0.6 7.9 4.7 0.2 3.5 0.9 1,605
SJVAPCD
Threshold 10 100 10 27 15 15 None
Exceed
SJVAPCD
Threshold? No No
Yes, 2019-
2023 No No No N/A
Conformity
Threshold 10 100 10 100 100 100 25,000
Exceed
Conformity
Threshold? No No
Yes, 2019-
2023 No No No No
SO2 emissions not estimated by RCEM. However, SO2 typically less than 5 percent of PM10 exhaust. Consequently, SO2 conservatively assumed to equal 5 percent of PM10. RECM does not estimate emissions after 2025. Therefore, the values shown for 2025 through 2031 are based on 2025 emission factors.
Actual emissions would be slightly lower than those shown.
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-10: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-11 shows that mitigating NOx emissions using Tier 3 vehicles would reduce emissions to below 10 tons per year during all years of construction.
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-11: Alternative 7a Mitigated NOx emissions
Year
NOx
(tons/yr) Year NOx (tons/yr)
2019 8.1 2023 7.5
2020 7.7 2024 3.8
2021 6.7 2025-2029 3.9
2022 8.7
SJVAPCD Threshold 10 Conformity Threshold 10
Exceed SJVAPCD Threshold? No Exceed Conformity Threshold? No Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2023. Table 5-12 shows the estimated cost of entering into a VERA to offset the 71.2 tons of NOx that would be emitted by Alternative 7a between 2019 and 2023, which are the years when NOx would exceed the Federal NOx conformity threshold.
Table 5-12: Alternative 7a Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 71.2
Estimated Mitigation Fee (per ton) $ 9,350
Total Cost $ 665,720
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510. First row shows total NOx emissions for each year when emissions exceed 10 tons.
With implementation of either measure, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Impact
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. According to OEHHA, health risk assessments should be based on a 70-year exposure period. However, such assessments should be limited to the period of the activities associated with a project.
The length of time that off-road equipment would operate near sensitive receptors would be relatively short.
As levee work is completed, equipment typically would progress along the levee alignments and would not operate within 500 feet of any one receptor for more than a few weeks at a time. Receptors located within 500 feet of borrow areas could be exposed for longer periods. The program’s overall construction emissions would not be concentrated in 1 particular area and would not result in an additive exposure mechanism.
Because the exposure period for receptors near construction areas would be substantially less than the required exposure period for health risk assessments (i.e., 70 years) and since construction emissions would be spread over a large geographical area, health risks were evaluated qualitatively. For these reasons, it is unlikely that construction activities would expose sensitive receptors to substantial DPM concentrations.
Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1209
Lower San Joaquin River
5-87
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Impact
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, several pieces of construction equipment would need to operate concurrently in a relatively small area to generate a constant plume of diesel exhaust that would cause objectionable odors for a substantial number of people. These circumstances would not occur as part of the project. Construction activities would move on a regular basis, which is typical of linear construction projects. This movement minimizes the potential for a substantial exposure to objectionable odors. Since construction activities would not generate odors that would affect a substantial number of people, this impact is considered to be less than significant.
Mitigation
No mitigation is required.
Impact
Maintenance related activities would occur periodically once construction is completed. Such activities occur periodically now and future increases in maintenance activities are expected to be minor. Operational maintenance activities would occur at a low frequency and intensity and would not generate substantial direct emissions of criteria pollutants, toxic air contaminants or odors. Because maintenance activities would result in only a minimal increase in operational emissions relative to existing conditions, such activities would not exceed SJVAPCD’s significance thresholds. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
Construction equipment, material delivery trucks and employee trips would be operated during levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
GHGs emitted during near-term construction would not be immediately offset by GHG emissions avoided through flood-protection, although the mitigation measures specified for 7A_AQ-1 will also reduce GHG emissions. In addition and consistent with DWR BMPs, the following measures should be implemented to reduce GHG emissions (California DWR, 2012):
Avoid tillage and maintain vegetation on levees and other properties to the extent possible to maximize carbon sequestration.
At construction sites, seed or plant native grasses and wildflowers in disturbed areas where feasible since those species are best adapted to local conditions and will often require minimal maintenance once established.
Reduce vegetation manipulation (mowing or spraying herbicides) when possible while maintaining proper function of the levee or property for its intended purpose. Mow vegetation if necessary rather than applying herbicides. If mowing is conducted, use fuel efficient mowers in proper working condition and minimize idling time by requiring that equipment be shut down after five minutes when not in use.
Carefully plan and schedule vegetation maintenance activities to minimize driving time and return trips to a site.
ATTACHMENT D 1210
Lower San Joaquin River
5-88
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing flood protection would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities. Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-9). Implementation would reduce flood risks and therefore would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 7a’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
Alternative 7b Mitigation
The emissions shown in Table 5-13 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The same measures to reduce NOx emissions would be implemented as described for Alternative 7a.
Implementation of either measure will reduce NOx emissions during construction. The use of Tier 3 offroad vehicles will result in emission reductions as shown in Table 5-14. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5. However, those emission reductions are not shown in Table 5-15 because the unmitigated emissions of these other pollutants (Table 5-13) are below State and Federal significance thresholds.
ATTACHMENT D 1211
Lower San Joaquin River
5-89
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-13: Alternative 7b Annual Construction Emissions Calendar Year
ROG
(tons/
yr)
CO
(tons/yr
)
NOx
(tons/
yr)
SO2
(tons/yr
)
PM10
(tons/yr)
PM2.5
(tons/
yr)
CO2e
(metric
tons/yr)
2019 1.5 10.1 19.1 0.4 7.2 2.0 4,461
2020 1.4 10.1 16.7 0.4 7.1 2.0 4,415
2021 1.3 10.2 13.4 0.4 7.1 1.9 4,407
2022 1.9 18.0 16.3 0.4 7.5 2.1 5,986
2023 1.8 17.9 14.9 0.4 7.4 2.1 5,978
2024 1.7 17.9 13.9 0.4 7.4 2.0 5,981
2025 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2026 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2027 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2028 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2029 0.6 5.9 5.0 0.3 5.3 1.3 1,812
2030 0.4 4.3 3.3 0.3 5.8 1.3 1,021
2031 0.4 4.0 3.0 0.2 4.7 1.1 857
SJVAPCD Threshold 10 100 10 27 15 15 None
Exceed SJVAPCD
Threshold? No No
Yes,
2019-
2028 No No No N/A
Conformity Threshold 10 100 10 100 100 100 25,000
Exceed Conformity
Threshold? No No
Yes,
2019-
2028 No No No No
SO2 emissions not estimated by RCEM. However, SO2 typically less than 5 percent of PM10 exhaust. Consequently, SO2 conservatively assumed to equal 5 percent of PM10. RECM does not estimate emissions after 2025. Therefore, the values shown for 2025 through 2031 are based on 2025 emission factors. Actual emissions would be slightly lower than those shown.
Table 5-14: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-15 shows that mitigating NOx emissions using Tier 3 vehicles would reduce emissions to below 10 tons per year during all years of construction.
ATTACHMENT D 1212
Lower San Joaquin River
5-90
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-15: Alternative 7b Mitigated NOx Emissions
Year NOx (tons/yr) Year NOx (tons/yr)
2019 8.8 2026 8.2
2020 8.4 2027 8.2
2021 7.5 2028 8.2
2022 9.7 2029 4.1
2023 9.7 2030 3.3
2024 9.8 2031 3.0
2025 8.2
SJVAPCD Threshold 10 Conformity Threshold 10
Exceed SJVAPCD
Threshold? No Exceed Conformity Threshold? No
Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2024. Table 5-16 shows the estimated cost of entering into a VERA to offset the 94.3 tons of NOx that would be emitted by Alternative 7b between 2019 and 2024.
Table 5-16: Alternative 7b Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 94.3
Estimated Mitigation Fee (per ton) $ 9,350
Total Cost $ 882,164
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510. First row shows total NOx emissions for each year when emissions exceed 10 tons.
With implementation of either measure, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. The potential impacts of exposure to TACs is the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, the potential impact is the same as Alternative 7a. Therefore, this impact is considered to be less than significant.
Mitigation
No mitigation is required.
Impact
Maintenance related activities would occur periodically once construction is complete. Such maintenance activities would be the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1213
Lower San Joaquin River
5-91
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Impact
Construction equipment, material delivery trucks and employee trips would be operated during in-place levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
The mitigation measures for 7B_AQ-1 would be the same as Alternative 7a.
Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing flood protection would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities.
Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-9). Implementation would reduce flood risks and, therefore, would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 7b’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
Alternative 8a Mitigation
The emissions shown in Table 5-17 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The following measures focus on reducing NOx emissions. The Lead Agency shall either:
ATTACHMENT D 1214
Lower San Joaquin River
5-92
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Require the use of off-road equipment that meets or exceeds USEPA or CARB Tier 3 off-road emission standards for all off-road vehicles greater than 25 horsepower and operating for more than 20 total hours over the entire duration of construction activities. Prior to issuance of a construction permit, the prime contractor(s) shall prepare and submit a Construction Emissions Minimization Plan (Plan) to the Lead Agency for review and approval. The Plan shall include estimates of the construction timeline by phase with a description of each piece of equipment required for every construction phase. Equipment descriptions and information shall include: equipment type, equipment manufacturer, equipment identification number, engine model year, engine certification (Tier rating), horsepower, engine serial number and expected fuel usage and hours of operation.
The Plan shall be kept by the Lead Agency and made available for review by any persons requesting it. Quarterly reports shall be submitted by the prime contractor(s) to the Lead Agency indicating the construction phase and equipment information used during each phase for the previous quarter; or
Enter into a VERA with SJVAPCD. The VERA would require payment of a fee to SJVAPCD that would be used to purchase NOx emission reductions to offset all NOx emissions during years when the Project’s unmitigated NOx emissions exceed ten tons. The VERA will be entered into prior to initiating the project and posted on Lead Agency website. The NOx offsets developed by the fee will be provided to the Lead Agency and also posted on the Lead Agency’s website. The information posted shall be posted in a location that is easy to access by the public and must remain on the website for one full year after all construction is completed.
Implementation of either measure listed above will reduce NOx emissions during construction. The use of Tier 3 off-road vehicles will result in emission reductions as shown in Table 5-18. The emission reductions decrease over time because Tier 3 only vehicles are being compared to the average construction fleet and that fleet gets cleaner over time as older vehicles are replaced by newer, lower emitting equipment. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5.
ATTACHMENT D 1215
Lower San Joaquin River
5-93
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-17: Alternative 8a Annual Construction Emissions Calendar Year
ROG
(tons/yr)
CO
(tons/yr)
NOx
(tons/yr)
SO2
(tons/yr)
PM10
(tons/yr)
PM2.5
(tons/yr)
CO2e
(metric
tons/yr)
2019 1.5 10.1 19.1 0.4 7.2 2.0 4,461
2020 1.4 10.1 16.7 0.4 7.1 2.0 4,414
2021 1.3 10.2 13.4 0.4 7.1 1.9 4,407
2022 1.9 17.8 16.0 0.3 6.1 1.8 5,932
2023 1.8 17.7 14.6 0.3 6.0 1.8 5,924
2024 1.3 14.1 10.8 0.3 5.4 1.5 3,536
2025 0.8 9.2 6.1 0.2 4.0 1.0 2,405
2026 0.8 9.2 6.1 0.2 4.0 1.0 2,405
2027 0.8 9.2 6.1 0.2 4.0 1.0 2,405
2028 0.8 9.2 6.1 0.2 4.0 1.0 2,405
2029 0.8 9.2 6.1 0.2 4.0 1.0 2,405
SJVAPCD
Threshold 10 100 10 27 15 15 None
Exceed
SJVAPCD
Threshold?
No No Yes, 2019-
2024 No No No N/A
Conformity
Threshold 10 100 10 100 100 100 25,000
Exceed
Conformity
Threshold?
No No Yes, 2019-
2024 No No No No
Table 5-18: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-19 shows mitigating NOx emissions using Tier 3 vehicles. This mitigation would reduce emissions to below 10 tons per year during all years of construction.
ATTACHMENT D 1216
Lower San Joaquin River
5-94
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-19: Alternative 8a Mitigated NOx emissions
Year NOx (tons/yr) Year NOx (tons/yr)
2019 8.8 2025 5.0
2020 8.4 2026 5.0
2021 7.5 2027 5.0
2022 9.6 2028 5.0
2023 9.5 2029 5.0
2024 7.6
SJVAPCD Threshold 10 Conformity
Threshold 10
Exceed SJVAPCD Threshold? No Exceed Conformity
Threshold? No
Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2024. Table 5-20 shows the estimated cost of entering into a VERA to offset the 90.7 tons of NOx that would be emitted by Alternative 8a between 2019 and 2024.
Table 5-20: Alternative 8a Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 90.7
Estimated Mitigation Fee (per ton) $ 9,350
Total Cost $ 848,045
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510. First row shows total NOx emissions for each year when emissions exceed 10 tons. First row shows total NOx emissions for each year when emissions exceed 10 tons.
With implementation of either measure, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Mitigation
No mitigation is required.
Impact
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. The potential impacts of exposure to TACs is the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, the potential impact is the same as Alternative 7a. Therefore, this impact is considered to be less than significant.
ATTACHMENT D 1217
Lower San Joaquin River
5-95
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Mitigation
No mitigation is required.
Impact
Maintenance related activities would occur periodically once construction is complete. Such maintenance activities would be the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
Construction equipment, material delivery trucks and employee trips would be operated during in-place levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
The mitigation measures for 8A_AQ-1 would be the same as Alternative 7a.
Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing FRM would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities.
Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-13). Implementation would reduce flood risks and therefore would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 8a’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1218
Lower San Joaquin River
5-96
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Alternative 8b Mitigation
The emissions shown in Table 5-21 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The following measures focus on reducing NOx emissions. The Lead Agency shall either:
• Require the use of off-road equipment that meets or exceeds USEPA or CARB Tier 3 off-road emission standards for all off-road vehicles greater than 25 horsepower and operating for more than 20 total hours over the entire duration of construction activities. Prior to issuance of a construction permit, the prime contractor(s) shall prepare and submit a Construction Emissions Minimization Plan (Plan) to the Lead Agency for review and approval. The Plan shall include estimates of the construction timeline by phase with a description of each piece of equipment required for every construction phase. Equipment descriptions and information shall include: equipment type, equipment manufacturer, equipment identification number, engine model year, engine certification (Tier rating), horsepower, engine serial number and expected fuel usage and hours of operation.
The Plan shall be kept by the Lead Agency and made available for review by any persons requesting it. Quarterly reports shall be submitted by the prime contractor(s) to the Lead Agency indicating the construction phase and equipment information used during each phase for the previous quarter; or
• Enter into a VERA with SJVAPCD. The VERA would require payment of a fee to SJVAPCD that would be used to purchase NOx emission reductions that would offset all NOx emissions during years when the Project’s unmitigated NOx emissions exceed ten tons. The VERA will be entered into prior to initiating the project and posted on Lead Agency website. The NOx offsets developed by the fee will be provided to the Lead Agency and also posted on the Lead Agency’s website. The information shall be posted in a location that is easy to access by the public and must remain on the website for 1 full year after all construction is complete.
Implementation of either measure listed above will reduce NOx emissions during construction. The use of Tier 3 off-road vehicles will result in emission reductions as shown in Table 5-22. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5.
ATTACHMENT D 1219
Lower San Joaquin River
5-97
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-21: Alternative 8b Annual Construction Emissions Calendar
Year
ROG
(tons/yr)
CO
(tons/yr)
NOx
(tons/yr)
SO2
(tons/yr)
PM10
(tons/yr)
PM2.5
(tons/yr)
CO2e
(metric
tons/yr)
2019 1.5 10.1 19.1 0.4 7.2 2.0 4,461
2020 1.4 10.1 16.7 0.4 7.1 2.0 4,415
2021 1.3 10.2 13.4 0.4 7.1 1.9 4,407
2022 1.9 18.0 16.3 0.4 7.5 2.1 5,986
2023 1.8 17.9 14.9 0.4 7.4 2.1 5,978
2024 1.7 17.9 13.9 0.4 7.4 2.0 5,981
2025 1.3 14.0 10.2 0.4 7.2 1.8 5,134
2026 1.3 14.0 10.2 0.4 7.2 1.8 5,134
2027 1.3 14.0 10.2 0.4 7.2 1.8 5,134
2028 1.3 14.0 10.2 0.4 7.2 1.8 5,134
2029 0.7 6.5 5.5 0.3 6.3 1.5 2,007
2030 0.7 6.5 5.5 0.3 6.3 1.5 2,007
2031 0.7 6.5 5.5 0.3 6.3 1.5 2,007
SJVAPCD
Threshold 10 100 10 27 15 15 None
Exceed
SJVAPCD
Threshold?
No No
Yes,
2019-
2028
No No No N/A
Conformity
Threshold 10 100 10 100 100 100 25,000
Exceed
Conformity
Threshold?
No No
Yes,
2019-
2028
No No No No
Table 5-22: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-23 shows the results of mitigating NOx emissions using Tier 3 vehicles. This mitigation would reduce emissions to below 10 tons per year during all years of construction.
ATTACHMENT D 1220
Lower San Joaquin River
5-98
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-23: Alternative 8b Mitigated NOx Emissions
Year NOx (tons/yr) Year NOx (tons/yr)
2019 8.8 2026 8.4
2020 8.4 2027 8.4
2021 7.5 2028 8.4
2022 9.7 2029 4.5
2023 9.7 2030 4.5
2024 9.8 2031 4.5
2025 8.4
SJVAPCD Threshold 10 Conformity Threshold 10
Exceed SJVAPCD Threshold? No Exceed Conformity Threshold? No Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2028. Table 5-24 shows the estimated cost of entering into a VERA to offset the 135.0 tons of NOx that would be emitted by Alternative 8b between 2019 and 2024.
Table 5-24: Alternative 8b Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 135.0
Estimated Mitigation Fee (per ton) $ 9,350.00
Total Cost $ 1,262,250
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510. First row shows total NOx emissions for each year when emissions exceed 10 tons. First row shows total NOx emissions for each year when emissions exceed 10 tons.
With implementation of either measure, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Mitigation
No mitigation is required.
Impact
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. The potential impacts of exposure to TACs are the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1221
Lower San Joaquin River
5-99
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Impact
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, the potential impact is the same as Alternative 7a. Therefore, this impact is considered to be less than significant.
Mitigation
No mitigation is required.
Impact
Maintenance related activities would occur periodically once construction has been completed. Such maintenance activities would be the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
Construction equipment, material delivery trucks and employee trips would be operated during in-place levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
The mitigation measures for 8B_AQ-1 would be the same as Alternative 7a.
Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood-risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing flood protection would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities.
Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-21). Implementation would reduce flood risks and therefore would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 8b’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1222
Lower San Joaquin River
5-100
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Alternative 9a Mitigation
The emissions shown in Table 5-25 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The following measures focus on reducing NOx emissions. The Lead Agency shall either:
• Require the use of off-road equipment that meets or exceeds USEPA or CARB Tier 3 off-road emission standards for all off-road vehicles greater than 25 horsepower and operating for more than 20 total hours over the entire duration of construction activities. Prior to issuance of a construction permit, the prime contractor(s) shall prepare and submit a Construction Emissions Minimization Plan (Plan) to the Lead Agency for review and approval. The Plan shall include estimates of the construction timeline by phase with a description of each piece of equipment required for every construction phase. Equipment descriptions and information shall include: equipment type, equipment manufacturer, equipment identification number, engine model year, engine certification (Tier rating), horsepower, engine serial number and expected fuel usage and hours of operation.
The Plan shall be kept by the Lead Agency and made available for review by any persons requesting it. Quarterly reports shall be submitted by the prime contractor(s) to the Lead Agency indicating the construction phase and equipment information used during each phase for the previous quarter; or
• Enter into a VERA with SJVAPCD. The VERA would require payment of a fee to SJVAPCD that would be used to purchase NOx emission reductions that would offset all NOx emissions during years when the Project’s unmitigated NOx emissions exceed ten tons. The VERA will be entered into prior to initiating the project and posted on the Lead Agency website. The NOx offsets developed by the fee will be provided to the Lead Agency and also posted on the Lead Agency’s website. The information shall be posted in a location that is easy to access by the public and must remain on the website for 1 full year after all construction is complete.
Implementation of either measure listed above will reduce NOx emissions during construction. The use of Tier 3 off-road vehicles will result in emission reductions as shown in Table 5-26. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5.
ATTACHMENT D 1223
Lower San Joaquin River
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San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-25: Alternative 9a Annual Construction Emissions Calendar Year
ROG
(tons/yr)
CO
(tons/yr)
NOx
(tons/yr)
SO2
(tons/yr)
PM10
(tons/yr)
PM2.5
(tons/yr)
CO2e
(metric
tons/yr)
2019 1.3 8.8 17.7 0.3 6.7 1.9 3,661
2020 1.2 8.8 15.3 0.3 6.7 1.8 3,614
2021 1.1 8.9 12.0 0.3 6.6 1.8 3,606
2022 1.7 16.5 14.6 0.3 5.7 1.7 5,132
2023 1.4 14.1 11.6 0.3 5.4 1.5 3,535
2024 0.7 8.2 5.3 0.2 4.7 1.1 1,759
2025 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2026 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2027 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2028 0.6 7.9 4.7 0.2 3.5 0.9 1,605
2029 0.6 7.9 4.7 0.2 3.5 0.9 1,605
SJVAPCD
Threshold 10 100 10 27 15 15 None
Exceed
SJVAPCD
Threshold?
No No Yes,
2019-2023 No No No N/A
Conformity
Threshold 10 100 10 100 100 100 25,000
Exceed
Conformity
Threshold?
No No Yes,
2019-2023 No No No No
Table 5-26: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-27shows the resulting mitigated NOx emissions using Tier 3 vehicles. This mitigation would reduce emissions to below 10 tons per year during all years of construction.
ATTACHMENT D 1224
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-27: Alternative 9a Mitigated NOx Emissions
Year NOx (tons/yr) Year NOx (tons/yr)
2019 8.1 2025 3.9
2020 7.7 2026 3.9
2021 6.7 2027 3.9
2022 8.7 2028 3.9
2023 7.5 2029 3.9
2024 3.8
SJVAPCD Threshold 10 Conformity Threshold 10
Exceed SJVAPCD Threshold? No Exceed Conformity
Threshold? No
Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2023. Table 5-28 shows the estimated cost of entering into a VERA to offset the 71.2 tons of NOx that would be emitted by Alternative 9a between 2019 and 2024.
Table 5-28: Alternative 9a Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 71.2
Estimated Mitigation Fee (per ton) $ 9,350
Total Cost $ 665,720
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510. First row shows total NOx emissions for each year when emissions exceed 10 tons.
With implementation of either option, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Mitigation
No mitigation is required.
Impact
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. The potential impacts of exposure to TACs is the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, the potential impact is the same as Alternative 7a. Therefore, this impact is considered to be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1225
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Impact
Maintenance related activities would occur periodically once construction is complete. Such maintenance activities would be the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
Construction equipment, material delivery trucks and employee trips would be operated during in-place levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
The mitigation measures for 9A_AQ-1 would be the same as Alternative 7a.
Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood-risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing flood protection would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities.
Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-25). Implementation would reduce flood risks and, therefore, would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 9a’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1226
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Alternative 9b Mitigation
The emissions shown in Table 5-29 already account for fugitive dust reductions required by SJVAPCD Regulation VIII - Fugitive PM10 Prohibitions. Since emissions of both PM10 and PM2.5 are less than the significance thresholds, no additional measures are proposed. The following measures focus on reducing NOx emissions. The Lead Agency shall either:
• Require the use of off-road equipment that meets or exceeds USEPA or CARB Tier 3 off-road emission standards for all off-road vehicles greater than 25 horsepower and operating for more than 20 total hours over the entire duration of construction activities. Prior to issuance of a construction permit, the prime contractor(s) shall prepare and submit a Construction Emissions Minimization Plan (Plan) to the Lead Agency for review and approval. The Plan shall include estimates of the construction timeline by phase with a description of each piece of equipment required for every construction phase. Equipment descriptions and information shall include: equipment type, equipment manufacturer, equipment identification number, engine model year, engine certification (Tier rating), horsepower, engine serial number and expected fuel usage and hours of operation.
The Plan shall be kept by the Lead Agency and be available for review by any persons requesting it. Quarterly reports shall be submitted by the prime contractor(s) to the Lead Agency indicating the construction phase and equipment information used during each phase for the previous quarter; or
• Enter into a VERA with SJVAPCD. The VERA would require payment of a fee to SJVAPCD that would be used to purchase NOx emission reductions that would offset all NOx emissions during years when the Project’s unmitigated NOx emissions exceed ten tons. The VERA will be entered into prior to initiating the project and posted on Lead Agency website. The NOx offsets developed by the fee will be provided to the Lead Agency and also posted on the Lead Agency’s website. The information shall be posted in a location that is easy to access by the public and must remain on the website for 1 full year after all construction is complete.
Implementation of either measure listed above will reduce NOx emissions during construction. The use of Tier 3 off-road vehicles will result in emission reductions as shown in Table 5-30. The use of Tier 3 only vehicles also results in reductions of other criteria pollutants: ROG, CO, PM10 and PM2.5.
ATTACHMENT D 1227
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-29: Alternative 9b Annual Construction Emissions Calendar Year
ROG
(tons/yr)
CO
(tons/yr)
NOx
(tons/yr)
SO2
(tons/yr)
PM10
(tons/yr)
PM2.5
(tons/yr)
CO2e
(metric
tons/yr)
2019 1.5 10.1 19.1 0.4 7.2 2.0 4,461
2020 1.4 10.1 16.7 0.4 7.1 2.0 4,415
2021 1.3 10.2 13.4 0.4 7.1 1.9 4,407
2022 1.9 18.0 16.3 0.4 7.5 2.1 5,986
2023 1.8 17.9 14.9 0.4 7.4 2.1 5,978
2024 1.7 17.9 13.9 0.4 7.4 2.0 5,981
2025 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2026 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2027 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2028 1.3 14.2 10.0 0.3 6.7 1.7 3,560
2029 0.6 5.9 5.0 0.3 5.3 1.3 1,812
2030 0.4 4.3 3.3 0.3 5.8 1.3 1,021
2031 0.4 4.0 3.0 0.2 4.7 1.1 857
SJVAPCD
Threshold 10 100 10 27 15 15 None
Exceed
SJVAPCD
Threshold? No No
Yes,
2019-2024 No No No N/A
Conformity
Threshold 10 100 10 100 100 100 25,000
Exceed
Conformity
Threshold? No No
Yes,
2019-2024 No No No No
SO2 emissions not estimated by RCEM. However, SO2 typically less than 5 percent of PM10 exhaust. Consequently, SO2 conservatively assumed to equal 5 percent of PM10.
Table 5-30: NOx Reductions from Implementation of Tier 3 Mitigation Construction Year NOx Reductions
2019 54 percent
2020 50 percent
2021 44 percent
2022 40 percent
2023 35 percent
2024 29 percent
2025-2029 17 percent
NOx emission reduction percentages calculated using CalEEMod2013.2.2. Numbers reflect reductions of an all Tier 3 fleet compared to average fleet mix.
Table 5-31 shows the resulting mitigated NOx emissions using Tier 3 vehicles. This mitigation would reduce emissions to below 10 tons per year during all years of construction.
ATTACHMENT D 1228
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Table 5-31: Alternative 9b Mitigated NOx Emissions
Year
NOx
(tons/yr) Year NOx (tons/yr)
2019 8.8 2026 8.2
2020 8.4 2027 8.2
2021 7.5 2028 8.2
2022 9.7 2029 4.1
2023 9.7 2030 2.8
2024 9.8 2031 2.5
2025 8.2
SJVAPCD Threshold 10 Conformity Threshold 10
Exceed SJVAPCD Threshold? No Exceed Conformity Threshold? No Alternatively, the purchase of emission offsets through a VERA would completely offset the Project’s NOx emissions from 2019 through 2029. Table 5-32 shows the estimated cost of entering into a VERA to offset the 94.3 tons of NOx that would be emitted by Alternative 9b between 2019 and 2024.
Table 5-32: Alternative 9b Construction NOx Mitigation Fee Calculation Total Unmitigated NOx Exceeding 10 Tons per Year 94.3
Estimated Mitigation Fee (per ton) $ 9,350
Total Cost $ 881,705
Cost per ton is based on the San Joaquin Valley Air Pollution Control District’s NOx fee included in their Indirect Source Rule 9510.
With implementation of either measure, the use of all Tier 3 vehicles or a VERA, this impact would be reduced to less than significant.
Mitigation
No mitigation is required.
Impact
Construction activities would generate short-term emissions of DPM exhaust. CARB identified DPM as a TAC. In assessing health risks from TACs, the dose to which sensitive receptors are exposed is the primary factor used to evaluate health risks. The potential impacts of exposure to TACs is the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
During construction, diesel exhaust produced by off-road construction equipment could generate odors.
However, the potential impact is the same as Alternative 7a. Therefore, this impact is considered to be less than significant.
Mitigation
No mitigation is required.
ATTACHMENT D 1229
Lower San Joaquin River
5-107
Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Impact
Maintenance related activities would occur periodically once construction has been completed. Such maintenance activities would be the same as in Alternative 7a. Therefore, this impact would be less than significant.
Mitigation
No mitigation is required.
Impact
Construction equipment, material delivery trucks and employee trips would be operated during in-place levee reconstruction and improvements. The resulting combustion of diesel and gasoline would emit GHGs.
The mitigation measures for 9B_AQ-1 would be the same as Alternative 7a.
Mitigation
No mitigation is required.
Impact
Levee repairs and improvements would provide future flood risk protection, as well as carbon sequestration due to restoration of riparian habitat associated with levee repair and improvement. Providing flood protection would result in net avoided GHG emissions associated with emergency response and rebuilding of flooded communities. Based on a review of this alternative, the following can be determined:
The construction-related and operational GHG emissions would not conflict with or be inconsistent with any current plan to reduce or mitigate GHGs.
Emissions would not exceed 25,000 metric tons of CO2e per year (Table 5-29). Implementation would reduce flood risks and therefore would reduce future GHG emissions resulting from flooding or flood damage remediation.
Based on this evaluation, Alternative 9b’s emissions would likely be offset to a substantial degree by avoided future GHG emissions from future flood damage prevention. Therefore, relative to existing conditions, the impact of the net change in GHG emissions would not be cumulatively considerable and this impact would be less than significant.
Mitigation
No mitigation is required.
VEGETATION
This section describes the affected environment and environmental consequences relating to vegetation for the LSJR project and the significance of the impacts and mitigation measures to reduce impacts.
ENVIRONMENTAL SETTING
Regulatory Framework
Laws, regulations and requirements that apply to vegetation are below and summarized in Chapter 7.
ATTACHMENT D 1230
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Federal
Executive Order 13112: Invasive Species
Federal ESA
Fish and Wildlife Coordination Act (FWCA)
State
California ESA
CFGC, Section 1600
California Native Plant Protection Act
Porter-Cologne Water Quality Control Act
Local
City of Lathrop General Plan (Polices 1, 2 and 7).
City of Lathrop General Plan (Goal 5, Policy 6; Goal 10) San Joaquin County General Plan (Objectives 1 and 2, Policies 1, 4, 5, 6,8; San Joaquin County Titles 9-1505 and 9-1510)
San Joaquin County Multi-species Habitat Conservation and Open Space Plan (SJCMSCP, San Joaquin County 2000)
Stockton General Plan 2035 (NCR-1 and NCR-2)
USACE Levee Vegetation Management Policy, 1110-2-583 (Vegetation ETL) New authorized projects are required by USACE policy to comply with ETL 1110-2-583, which calls for the removal of wild growth, trees and other vegetation that might impair levee integrity or flood-fighting access in order to reduce the risk of flood damage. In certain instances, to further enhance environmental values or to meet State or Federal laws and/or regulations, a variance can be requested from the standard vegetation guidelines. For a variance to be acceptable, safety, structural integrity and functionality of the levee must be maintained.
ATTACHMENT D 1231
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Issues with vegetation on levees are summarized as follows:
Levee Visibility – Riparian vegetation can cause a reduction in visibility, particularly in very dense areas of vegetation. Levee visibility is important for inspection crews to identify problems in levee integrity such as the presence of burrowing animals, cracks, slumping and seepage. Accessibility. Vegetation can block access to the levee crest of landside of the levee for flood fight requirements and maintenance access purposes.
Through-levee Seepage – Riparian vegetation roots can cause seepage problems and affect the general integrity of the levee.
Windthrow – The root balls of felled trees during storms can displace relatively large amounts of earth, which can affect the strength of the levee or if on the waterside, increase the risk of scour. Slope Stability – Riparian vegetation can cause slope stability problems, particularly on the waterside of levees. Tree roots extending in the river flow can cause erosion near the toe of the levee, a particularly critical part in terms of slope stability. Burrowing Animals – Riparian vegetation may encourage the development of animal burrows detrimental to the levee or may reduce visibility of burrows.
Existing Conditions
Historic native vegetation in the project area has been highly altered and fragmented as a result of urbanization, agriculture, FRM and navigation projects, including levees and constructed channels like the Stockton Diverting Canal. Vegetation within the project area includes remnant Great Valley cottonwood riparian forest, Great Valley oak riparian forest, nonnative woodland, coastal and valley freshwater marsh, agricultural (row crops orchards and vineyards) and developed lands like lawns, parks and golf courses.
Nonnative vegetation is interwoven throughout the landscape. Open water habitat includes rivers, tributaries, canals and ditches. Ditches may contain water seasonally or year-round.
Once, the SJR and tributaries were framed by dense riparian forest. Today, riparian vegetation consists of narrow linear strips and occasional patches of riparian forest and riparian scrub growing on or adjacent to the levee. Larger areas of riparian forest are present in some areas where the levee is set back from the river or tributary, leaving floodplain on the waterside of the levee. More detailed description of the vegetation in the project area is provided below and is also available in the SJCMSCP (San Joaquin County, 2000) and in the Draft EIS/EIR for the RD 17 early implementation project (AECOM, 2011).
The primary focus of this section will be on areas the LSJR project area (encompassing the construction footprint, O&M and utility easements, roadway alignment and potential borrow sites), with attention, although not measurements, for lands adjacent to the project area. The northern portion of the project area includes Mosher Slough, Fivemile Slough, Fourteenmile Slough, Tenmile Slough and Stockton Deep Water Ship Channel. The central and southern portions include the SJR and its tributaries, including Calaveras River, Smith Canal, Old Mormon Slough, French Camp Slough and Duck Creek. The southern part of the project area is comprised of French Camp Slough and the SJR around RD 17. It occurs within the Great Central Valley subdivision of the California Floristic Province in San Joaquin County (Hickman, Ed., 1993). The topography of the portions of the project area adjacent to the levees is relatively level with elevations ranging from less than 5 feet to 38 feet above mean sea level.
Vegetation Types in the Project Area
This section is based upon a literature review.
ATTACHMENT D 1232
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Riparian Communities
In general, riparian communities are among the richest community types, in terms of structural and biotic diversity, of any plant community found in California. Riparian vegetation provided important ecological functions, including: wildlife habitat; migratory corridor for wildlife; filtering out pollutants and shading waterways, thereby improving water quality; providing connectivity between waterways and nearby uplands; provision of biomass (nutrients, insects, large woody debris, etc.) to adjacent waterways; and, in some situations, reducing the severity of floods by stabilizing riverbanks. Riparian forests and woodlands – even remnant patches – are important wildlife resources, because they continue to be used by a large variety of wildlife species and because of their regional and statewide scarcity.
Shaded Riverine Aquatic Habitat. SRA habitat is the nearshore aquatic zone composed of instream woody material providing in-water cover and shoreline trees and shrubs providing overhead canopy cover.
Overhanging trees and shrubs provide shade, an element of SRA cover important to the survival of many aquatic organisms, including fish. Overhanging vegetation moderates water temperatures, which is an important factor for various life stages of native fish species. The vegetation provides food and habitat for both terrestrial and aquatic invertebrates, which in turn serve as food for several fish species. Aquatic vegetation or in-water cover, provides a diversity of microhabitats that allow for high species diversity, abundance and a food source for instream invertebrates that in turn are eaten by several native fish species.
Thus, a broad food base and extensive cover and habitat niches are supported by in-water cover. These values in turn create high fish diversity and abundance (USFWS, 1992). Additional discussion of SRA is provided in Section 5.11, FISHERIES.
Riparian Woodland. Riparian woodlands in the project area include cottonwood riparian woodland, valley oak riparian woodland, walnut riparian woodland and riparian scrub. Riparian habitats are considered to be among the most productive and diverse wildlife habitats in California. In addition to providing important nesting and foraging habitat, they function as wildlife movement corridors.
Great Valley Cottonwood Riparian Forest. Larger remnant patches of Great Valley cottonwood riparian forest located within the project area are dominated by large Fremont cottonwood trees and Goodding’s willow. Most of the otherwise linear or smaller patchy areas of this community lack Fremont cottonwood and are represented by Goodding’s willow, red willow, arroyo willow, narrow leaved-willow and scattered valley oak, Oregon ash and buttonbush. Native ground cover species, mainly found in the larger remnant patches of riparian forest, include California blackberry and wild rose. Common nonnative understory species found in most elements include Himalayan blackberry and tree tobacco. Most of the Great Valley cottonwood riparian forest community could also be characterized as Great Valley riparian scrub, which does not include Fremont cottonwood and is characterized by a shorter canopy and more uniform structure.
However, this habitat is part of the Great Valley cottonwood riparian forest that was extensive and connected along this entire reach of the SJR and this document therefore describes all riparian habitat as such (AECOM, 2011).
Great Valley Oak Riparian Forest. Great Valley oak riparian forest is also located within the project area, occurring only on the landside of the levees. Two significant oak groves of very large, healthy valley oak trees are present on the landside in RD 17 and account for the majority of the Great Valley oak riparian forest; although several groups of smaller valley oak trees and individual valley oak trees scattered along the landside also contribute to this community. Although not measured, several of the largest trees in these landside oak groves present are close to 100 inches (diameter at breast height) dbh, which is a size that indicates they are possibly several hundred years old (Bartolome, 1997).
ATTACHMENT D 1233
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Herbaceous Community
Nonnative Annual Grasslands. Nonnative annual grassland occurs throughout the project area on levee slopes, along roadsides and in undeveloped parcels. These areas are dominated by nonnative annual grasses and ruderal vegetation and may support stands of noxious species. Ruderal vegetation and grassland generally occurs in disturbed areas, such as levee slopes and edges of agricultural fields and roads. Areas of pasture associated with residences are primarily annual grasses that are grazed by horses and were mapped as nonnative annual grassland. The annual grasslands in the project area contain a relatively large proportion of ruderal species, likely because of substantial disturbance from human activities.
Nonnative annual grassland is dominated by naturalized annual grasses with intermixed perennial and annual forbs. Grasses commonly observed in the project area are foxtail barley, ripgut brome, Italian ryegrass and soft chess. Other grasses are wild oats, Bermuda grass and rattail fescue. Forbs commonly observed in annual grasslands in the project area are yellow star-thistle, prickly lettuce, bristly ox-tongue, sweet fennel, Italian thistle, horseweed, black mustard, fireweed, broad-leaf pepper grass, common sunflower, pigweed, cheeseweed, bindweed and telegraph weed. The annual grasslands in the project area contain a relatively large proportion of ruderal species, likely because of substantial disturbance from human activities. Elderberry shrubs occur in several areas of nonnative annual grassland.
Ruderal vegetation is characterized by nonnative weedy and sometimes invasive vegetation and nonnative annual grasses. Common weed species include yellow star-thistle, black mustard, shortpod mustard, Italian thistle, milk thistle and Himalayan blackberry; common grass species include ripgut brome, foxtail barley, Bermuda grass and Johnsongrass. The levee slopes are dominated by ruderal vegetation. Large open areas in RD 17 are composed primarily of ruderal vegetation as are some smaller open areas that border roads, parking lots and agricultural land and Old Mormon Slough.
Agricultural Communities
In the project area, agricultural lands include row and field crops, fallow and disked agricultural fields orchards and vineyards. General farming practices result in monotypic stands of vegetation for the growing season and bare ground in the fall and winter. Irrigation ditches are a part of most agricultural fields in the project area.
Cropland occurs in RD 17, Shima Tract and Wright-Elmwood Tract northeast of the Stockton Diverting Canal and along the upper reaches of the Calaveras River. Ruderal species grow along the edges of fields and irrigation ditches, some of which contain water and associated aquatic plants.
Developed Lands
Developed lands in the project area include levee roads, railways, roads, buildings and landscaped areas as well as barren areas that were disturbed and are not vegetated. Developed areas consist of residential areas, parks, boat launching facilities, docks and ranch houses and related facilities. Vegetation in residential areas and parks consists of turf grasses, landscape trees and occasional valley oak trees. Ranch lands often contain a variety of landscape trees and shrubs and occasional native trees including valley oak trees. In north and central Stockton, most of the areas landside of levees in the project area are “developed.” This is also true of lands in the northern portion of RD 17 (Weston Ranch) and in southern RD 17 near Lathrop and Manteca.
Vegetation by Project Reach
Throughout the project area levee crowns are either paved or graveled for access and inspection and are generally devoid of vegetation.
ATTACHMENT D 1234
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Mosher Slough
Mosher Slough runs through a highly urbanized area. Woody riparian vegetation is most robust near the confluence with Fourteenmile Slough. It is comprised of typical Valley riparian trees and shrubs. Emergent wetland vegetation occurs intermittently at the water’s edge. Landside vegetation includes nonnative landscape trees and shrubs as well as natives. Typical wetland vegetation line some stretches of this reach.
Fourteenmile Slough, Fivemile Slough, Tenmile Slough
Waterward of the levees, some woody riparian trees and shrubs boarder these highly engineered waterways.
Within some of the sloughs and canals, aquatic weeds cover much of the water surface. Along the edges of the waterways, wetland vegetation is present intermittently. Within Fourteenmile Slough, intertidal vegetation is present on rocky substrate that is exposed during low tides. In Buckley Cove, near the confluence of Tenmile Slough with the Stockton Deep Water Ship Channel, wetland and subtidal vegetation is present along with aquatic weeds. Landside vegetation is comprised mainly of row crops with some parcels in orchard.
Stockton Deep Water Ship Channel
Native vegetation is mostly absent along the Stockton Deep Water Ship Channel, the exception being some scattered trees and shrubs along the landside toe drain and irrigation ditches.
SJR
On the SJR, lands waterside of the levees are very narrow and support a remnant riparian forest. Trees and shrubs occur in small patches or may be scattered individuals. Vegetation on the waterside of levee slopes is highly varied, ranging from ruderal herbaceous vegetation and annual grasses with few shrubs, to dense shrubs with little overstory, to mature riparian forest. Potential SRA cover is found along much of the river in the Central Stockton portion of the project area.
Dominant waterside tree species include cottonwood, willow, oak, box elder and black walnut. In the project area, common shrub species include willow, wild rose and blackberry. Elderberry shrubs are also present in some locations. Ruderal herbaceous vegetation is present on levee slopes. In some places, the tree overstory along the levee is so dense that the leaf fall and shading, as well as human activity, precludes development of dense understory vegetation (USFWS, 2007). At Dos Reis road, there is a park on both sides of the levee where vegetation includes willows, weeping willow, cottonwood, fruitless mulberry, mesquite (thorns), elderberry and mistletoe.
Landside levee slopes are primarily barren or covered with ruderal vegetation. Beyond the base of the levees, riparian vegetation is rare but occasionally present in small isolated patches. Other trees include occasional single or isolated stands of native oaks and nonnative trees planted around farms, agricultural fields and residential or other types of development. Larger remnant patches of Great Valley cottonwood riparian forest located within the study area are dominated by large Fremont cottonwood trees and Goodding’s willow (AECOM, 2011). Most of the otherwise linear or smaller patchy areas of this community lack Fremont cottonwood and are represented by Goodding’s willow, red willow, arroyo willow, narrow leaved-willow and scattered valley oak, Oregon ash and buttonbush (AECOM, 2011).
Native ground cover, mainly found in the larger remnant patches of riparian forest, include California blackberry and wild rose. Common nonnative understory species found in most elements include Himalayan blackberry and tree tobacco. Most of the Great Valley cottonwood riparian forest community could also be characterized as Great Valley riparian scrub, which does not include Fremont cottonwood and is characterized by a shorter canopy and more uniform structure; however, this habitat is part of the ATTACHMENT D 1235
Lower San Joaquin River
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Final Feasibility Report - Chapter 5 - January 2018
San Joaquin County, CA Affected Environment and Environmental Consequences Great Valley cottonwood riparian forest that was extensive and connected along this entire reach of the SJR and this document therefore describes all riparian habitat as such (AECOM, 2011).
Calaveras River
Levees and the lands adjacent to both the waterside and landside of the levees in the reach of the Calaveras River above and just below, the Stockton Diverting Canal are largely devoid of trees and shrubs. The exception is some orchards landward of the north levee. Moving downstream, more trees and shrubs are present on and adjacent to the levees. In the highly urbanized reaches, many of the landside trees and shrubs are associated with landscape plantings in yards, parks and public rights of way. Wetland vegetation appears to line the channel in places.
Stockton Diverting Canal (SDC)
Levees defining the SDC are clear of woody vegetation. Immediately landside of the southwestern levee is mainly urban and industrial uses, with a small portion in the southeast in agriculture (row crops and orchard). Landside of the northeastern levee is about equally divided between urban/industrial uses and agriculture. Waterward of both levees some native woody small trees and shrubs are scattered and wetland vegetation occurs at the water’s edge in some stretches.
Smith Canal
Smith Canal is surrounded by urban residential areas, including hard-scaping (sidewalks) and some landscape plantings adjacent to the water’s edge. Near the confluence of the canal with the SJR, there is a public park, including a picnic area, boat launch ramp and associated infrastructure. There is an irrigated lawn and a mixture of native and nonnative trees and shrubs. Wetland vegetation is prevalent at the water’s edge and nonnative invasive water plants inhabit the “bay” near the boat launch ramp. Invasive waterweeds occupy much of the inlet in the vicinity of the boat launch ramp.
Mormon Slough and Old Mormon Slough
Before construction of the Stockton Diverting Canal, Old Mormon Slough was connected to Mormon Slough and was perennial in most years. Today, the channel receives local stormwater runoff and intermittently contains water. Vegetation in and adjacent to the channel ranges from orchard and row crops, landscape plants, residual stands of native riparian plants, like willows and oaks and some isolated wetland plants. At the confluence of Old Mormon Slough with the SJR, riparian vegetation becomes taller and denser and well developed wetland vegetation is present.
French Camp Slough and Duck Creek
Levees along Duck Creek are clear of trees and shrubs. Adjacent lands are largely in agriculture with urban development beginning to extend into them. French Camp Slough upstream of the confluence with Duck Creek is very similar in character to Duck Creek. Levees are free of trees and shrubs and adjacent lands are in agriculture with urban lands extending towards the leveed slough.
The lower reaches of French Camp Slough (between Duck Creek and the SJR) are surrounded landward by urban development. The Weston Ranch residential development is immediately to the south in the northern portion of RD 17. A municipal golf course is adjacent to the northern bank/levee of French Camp Slough in Central Stockton. Between the north and south French Camp Slough levees is an “island” of land that is in agriculture. The perimeter of this island contains a fairly thick margin of trees and shrubs. The stretch along the SJR includes willow pole plantings installed by USACE as part of PL 84-99 levee rehabilitation efforts after the high water events of 2006.
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San Joaquin County, CA Affected Environment and Environmental Consequences In this lower French Camp Slough reach, the levee crown includes a paved road. The landside levee slope and toe are mostly devoid of vegetation. There are some annual grasses and herbs. These are largely nonnative weedy plants. Where trees and shrubs are present within the landside easement, they are mainly landscape plantings associated with public rights of way and private yards. The waterside levee slope and easement have trees and shrubs throughout their length, being quite dense in some areas. Trees include native valley oak, box elder, cottonwood, black walnut and willows. Elderberry shrubs and poison oak are also present. Snags are present as are patches of dead willow shrubs. In the canal between the RD 17 levee and the mid-channel island to the north, wetland plants are abundant. These include tules, nut sedges and tule potato. Water hyacinth, mistletoe and nonnative English walnut trees are also present.
Invasive Plants
Invasive plants in the project area include trees, shrubs, vines, grasses and herbs. These are species that are commonly encountered along Central Valley water courses and in vacant lands on the valley floor. In considering invasive species presence in the project area, the following resources were consulted: the California Department of Food and Agriculture Pest Ratings of Noxious Weed Species and Noxious Weed Seed (California Department of Food and Agriculture, 2010); the California Invasive Plant Council’s California Invasive Plant Inventory (California Invasive Plant Council 2006 (downloaded May 2013); 2007 CAL-IPC News with new species added to the inventory. The May reconnaissance site visit documented the occurrence of a number of these species on and adjacent to the existing levee and in Old Mormon Slough.
Nonnative species observed in the area (AECOM, 2011) include: barley, ripgut brome, Italian ryegrass and soft chess. Other grasses are wild oats, Bermuda grass and rattail fescue. Forbs commonly observed in annual grasslands in the project area are yellow star-thistle, prickly lettuce, bristly ox-tongue, sweet fennel, Italian thistle, horseweed, black mustard, fireweed, broad-leaf pepper grass, common sunflower, pigweed, cheeseweed, bindweed and telegraph flora. Nonnative invasive trees and shrubs in the project area include:
Tree of Heaven and Himalayan blackberry. Mistletoe is also found throughout the area.
ASSESSMENT METHODS AND BASIS OF SIGNIFICANCE
Assessment Methods
The methods used to identify and evaluate potential effects of the action alternatives on vegetation and wetland resources in the project area consisted of: a literature review focused on recent environmental documents and surveys addressing the project area; a reconnaissance-level site visit; review of the USFWS’ draft FWCA (USFWS, 2014) prepared for the LSJRFS; and viewing the landscape using Google EarthTM imagery and measurement tools. Coordination with USFWS and NMFS also contributed to this assessment.
Within the potential project construction and O&M footprints, the extent of existing woody vegetation, irrigated grass, golf courses and some wetlands was measured using the polygon measuring feature of Google Earth. The California Natural Diversity Database (CNDDB), California Native Plant Society’s (CNPS’s) Inventory of Rare and Endangered Plants of California and a USFWS list of species for the project region (CNDDB 2012; USFWS, 2013) were also consulted.
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San Joaquin County, CA Affected Environment and Environmental Consequences Reconnaissance-Level Site Visit and Vegetation Cover Mapping USACE, DWR and USFWS biologists conducted a reconnaissance-level visit to representative sites throughout the project area to observe existing vegetation and land cover. The field visits were conducted on May 29 and May 30, 2013. The purposes of these visits were to, at a reconnaissance level:
Identify vegetation and land cover types.
Evaluate whether potential habitat may be present for special-status plant species that were identified in the project region.
Identify potential waters of the U.S. and/or State, including wetlands. Identify invasive plant species present in the project area.
Vegetation cover mapping is broad-brush due to the limitations of the satellite imagery available through Google EarthTM. Vegetation mapped is: waterside trees and shrubs; landside trees and shrubs; wetlands; orchards/vineyards; row/field crops; irrigated grass; and ruderal vegetation. Vegetation typical of these broad categories is described in this section based upon observations during the reconnaissance visits and the literature review.
Impacts
The key effects were identified and evaluated based on the environmental characteristics of the project area, with specific attention to the footprint of the potential project and the magnitude, intensity and duration of activities related to the construction and operation of the proposed action alternatives.
Addressing Uncertainty Under NEPA and CEQA
Both NEPA and CEQA describe how impact analysis may proceed when complete information is lacking.
In these circumstances, the CEQ and CEQA encourage the use of incremental decision making through tiering and/or sequencing of impact analyses to ensure continued progress towards the critical path of meeting the overall project purpose and need (40 CFR 1508.28 and CEQA Guideline Sections 15152 and 15168).
In this FR/EIS/EIR, the anticipated construction-related activities associated with implementing the proposed action alternatives are addressed at a level considered appropriate given the current status of project planning and design and available information and data. As planning proceeds, USACE, CVFPB and SJAFCA will continue to refine measures, construction methods, equipment types and construction schedules with the intent of further reducing adverse impacts.
The approach used in this impact analysis is expected to overestimate the extent of existing vegetation and the extent of impacts on vegetation. As project planning proceeds, refinements to the measures and designs are anticipated and additional field-level information will become available to facilitate refinements to the impact assessment.
Effect Assumptions
The following assumptions were made regarding project effects on vegetation.
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San Joaquin County, CA Affected Environment and Environmental Consequences General Construction Impacts
All construction activities, including equipment staging and access, would take place only within the project area footprint or in existing off-site developed areas. For all alternatives, construction would be phased and occur over 12 years.
Construction Impacts on Vegetation
Construction of levee cutoff walls and slope reshaping would both result in removal of landside and waterside woody riparian vegetation.
Construction of seismic fixes would require removal of vegetation from levee slopes and both the waterside and landside easements.
Construction of levee height fixes and increases (to address sea level rise) would require removal of all vegetation from the landside levee slope and easement. For all proposed alternatives: new, reshaped or reconstructed levee slopes; seepage berms; would be hydroseeded with native grassland species after construction. These areas would, therefore, comprise upland habitat after construction.
Loss of agricultural and annual grassland vegetation (ruderal vegetation) would not be considered a significant adverse effect from a biological resource standpoint. These habitats are common and not considered sensitive native community types. They are also more easily reestablished after disturbance than riparian or wetland communities. The loss of agricultural and annual grassland habitats could be adverse for wildlife, however. This effect is discussed in Section 5.10, WILDLIFE.
Throughout the project area, levee crowns are either paved or graveled for access and inspection and generally devoid of vegetation. Except where trees and shrubs are present, impacts to levee crowns would not be considered a significant impact.
Borrow
Specific borrow locations have not been identified for the proposed project, but it is assumed that sufficient suitable materials would be available within a 25 mile radius. It is likely that borrow would come from lands that are currently in agriculture or fallow. Thus, impacted vegetation would be orchards/vineyards, row or field crops or ruderal vegetation. Sensitive habitats, including wetlands, would be avoided. Prior to excavating borrow, top soil would be removed and set aside.
Once material is extracted, the topsoil would be replaced and the borrow sites would be returned to their existing use wherever possible. Some borrow sites could be used to mitigate for project impacts, if appropriate.
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San Joaquin County, CA Affected Environment and Environmental Consequences Vegetation ETL
Compliance with USACE ETL 1110-2-583 vegetation requirements would be established at the time of construction of flood features in each reach. This would include either receipt of a vegetation variance, which would allow 25 percent of the waterside vegetation to remain on the lower two thirds of the levee slope and within the waterside easement, of full compliance with the VFZ in areas where a variance is not granted. The VFZ extends from 15 feet landward of the levee to 15 feet waterward and includes the levee slopes and crown. The VFZ would be seeded with a mixture of native grasses and forbs. No woody vegetation would be planted or allowed to grow on levees that comply with the VFZ or within 15 feet of them.
Routine project O&M will include maintaining these VFZs. If a vegetation variance is granted, USACE will seek opportunities to plant waterside vegetation as compensation for impacts to SRA and woody riparian habitats in accordance with the terms and conditions of the NMFS BO.
Operation and Maintenance
To establish, reestablish or maintain the required O&M and the inspection road on the landside of the levee, trees and shrubs would be removed from the landside from the levee toe, approximately 20 feet landward on new levees and between 10 and 20 feet on existing levees, consistent with existing O&M agreements. This O&M easement would be maintained clear of trees and shrubs through routine O&M (up to 4 times per year).
Effect Mechanisms
Vegetation and wetland resources could be directly and indirectly affected by the project alternatives. The following types of activities could cause varying degrees of effects on these resources. Vegetation removal for seepage berm and levee construction; utilization of borrow sites and recontouring of the existing levee. Grading and fill placement during construction of levee alternatives. Placement of slurry cutoff walls, interrupting groundwater connectivity. Channel dewatering or installation of temporary water-diversion structures. Temporary stockpiling and side-casting of soil, construction materials or other construction wastes. Soil compaction, dust and water runoff from the construction site into adjacent areas. Introduction or spread of invasive plant species into adjacent open space areas. Runoff of herbicides, fertilizers, diesel fuel, gasoline, oil, raw concrete or other toxic materials used for levee construction, O&M into sensitive biological resource areas (e.g., riparian habitat, wetlands).
Placement of rock slope protection on the waterside of levees. O&M activities, including removal of weeds, tree and shrub trimming up to 4 times per year and reconditioning of levee slopes and road with a bulldozer, as needed.
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San Joaquin County, CA Affected Environment and Environmental Consequences Basis of Significance
For this analysis, an environmental effect was significant if it would result in any of the effects listed below.
These effects are based on NEPA standards, State CEQA Guidelines Appendix G (14 CCR 15000 et seq.) and standards of professional practice.
Substantial loss, degradation or fragmentation of any natural communities or wildlife habitat. Substantial effects on any riparian habitat or other sensitive natural community identified in local or regional plans, policies or regulations or by NMFS, USFWS or CDFW. Conflict with the provisions of the San Joaquin County Multi-species Conservation and Open Space Plan (2000).
Conflict with the San Joaquin County General Plan, City of Stockton General Plan, Lathrop General Plan or the Manteca General Plan.
Effects on Vegetation
Impacts to vegetation for all alternatives are summarized in Table 5-33.
Table 5-33: Vegetation Effects by Alternatives
Vegetation
Alternatives
7a 7b 8a 8b 9a 9b
Natural Lands
SRA (lf) 19,630 49,586 25,674 51,985 25,508 51,819
Riparian Trees and Shrubs (acres) 139 274 160 245 152 237 Wetlands (acres) 10.75 15 11 15 11 15
Agricultural Lands
Orchards/Vineyards (acres) 0 95 0 95 4 99
Row/Field Crops (acres) 15 32 15 32 16 33
Irrigated Grass
Irrigated Grass (acres) 10 10 10 10 10 10
USACE Levee Vegetation Management Policy, ETL 1110-2-583 (Vegetation ETL) New authorized projects are required by USACE policy to comply with ETL 1110-2-583. For purposes of this feasibility study and impact assessment, USACE intends to pursue a vegetation variance, where appropriate, during PED. Where suitable, a vegetation variance would allow approximately 25 percent of waterside woody vegetation to be retained on the lower two thirds of the waterside levee slope and within 15 feet of the waterside levee toe. Under each alternative, compliance with the levee vegetation requirements through a variance would still result in permanent loss of trees and shrubs on and adjacent to the landside and upper third of levees and related FRM features, and a 75 percent reduction in trees and shrubs on the lower portion of the levee and within the waterside easement. This would have a substantial adverse and permanent effect from loss of riparian habitat. Therefore, for all alternatives these effects are considered permanent, significant and unavoidable.
ALTERNATIVE 1 - NO ACTION
In general, the No Action Alternative represents the continuation of existing levee conditions in the project area. USACE would not participate in construction of the proposed project. The No Action Alternative ATTACHMENT D 1241
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San Joaquin County, CA Affected Environment and Environmental Consequences assumes continued application of the existing O&M Manuals. Further, it assumes the continued existence of the vegetation conditions at the time of the analysis and assumes that maintenance would maintain generally the same configuration and extent of vegetation, except that it is assumed that trees and shrubs would continue to grow and mature. The consequences of levee failure and flooding are described under the No Action Alternative Description in Chapter 4, including a summary of environmental effects.
Without improvements to the levees and associated features of the FRM system, current levee system would not meet current state ULE criteria or Federal design standards for sea level rise. Flood fight activities would occur during a high flow emergency response. Flood fighting is usually performed by placing large rock along the levee slope to stop erosion and prevent levee failure and loss of lives. The placement of rock would prevent or impede future growth of trees and vegetation on the levee slopes. In the event that flood fighting activities were not successful and a levee failure occurred, all vegetation would be lost. The magnitude of the impacts would depend upon the location of the levee breach, severity of the storm and river flows at the time of flooding. Predicting these events and providing a determination of significance is not possible based on the information available at this time. Therefore, identification of potential effects is too speculative for meaningful consideration.
ALTERNATIVE 7A
Overall, the following vegetation could be removed or directly affected by implementation of Alternative 7a: 19,630 lf (lf) of SRA, 139 acres of riparian trees and shrubs, and 10.75 acres of wetlands. All woody riparian vegetation not removed for construction of the structural FRM features would be removed to achieve compliance with the Vegetation ETL, with the exception of approximately 25 percent of the waterside vegetation, which is assumed to remain under a vegetation variance. The levee slopes and 15 to 20 feet landward of the levee would be permanently maintained free of trees and shrubs. Once construction is complete, the landside levees and easements would be maintained free of woody vegetation. This impact is significant and unavoidable because it would eliminate, in perpetuity, nearly all remaining landside trees and shrubs throughout the project footprint.
North Stockton
Mosher Slough
Construction of cutoff walls on the southern levees between Thornton Road and the railroad tracks would require degrading the top half of the levee before installing the cutoff wall and reconstructing the levee.
This would result in removal of all vegetation on the upper half of the levees. Construction would occur from the top of the levee. The lower half of the waterside and landside levee slopes would not be directly affected by construction of project features. There could be some indirect impacts to this vegetation due to dust and vibration. Likewise, the waterside and landside easement would not be directly affected by construction of the levee cutoff walls.
From Shima Tract to Thornton Road, a cutoff wall would be installed and the levees would be raised to reduce risk from sea level rise. Waterside surface would remain where it is and the levee would be raised and extended landward. All vegetation would be removed from: the upper half of the waterside levee slope; all of the landside slope; and, all of the landside easement. Vegetation would remain on the lower half of the levee and within the waterside easement. There could be indirect impacts to this vegetation due to dust, vibration and movement of disturbed soils down-slope.
Construction on Mosher Slough would directly affect 21.5 acres of riparian trees and shrubs and 3 acres of wetlands on the levee and within 15 feet of the toe of the levee. This impact would be significant and ATTACHMENT D 1242
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San Joaquin County, CA Affected Environment and Environmental Consequences unavoidable because there would be a permanent loss of riparian habitat, including wetlands and loss of natural communities and wildlife habitat.
Fourteenmile Slough, Fivemile Slough, Tenmile Slough
A cutoff would be installed in the eastern levee of Shima Tract and erosion protection placed on the landside of the levee to provide protection from high water events originating from the West (Delta). As described above, cutoff wall construction would entail degrading the top half of the levee, installing and then reconstructing the levee. All vegetation would be removed from the top half of both the landside and waterside levee slopes. The lower half of the waterside levee slope and the waterside easement would not be affected by project construction. Because of the addition of erosion protection on the landside of the levee, the lower half of the levee and the easement would be affected by project construction.
The remainder of the levee improvements consist of a combination of levee slope reshaping, landside erosion protection and/or levee height fixes. Construction of these levee improvements would require removal of all levee slope and levee easement vegetation. Improved FRM in this reach includes installation and operation of a closure structure. This structure would permanently affect 0.5 acres of open water and intertidal habitat. An additional 1 acre would be affected during construction of the closure structure.
Construction on Shima Tract, Fivemile Slough, Fourteenmile Slough and Tenmile Slough would directly affect 4 acres of waterside wetlands and 30.75 acres of woody riparian trees and shrubs. It would also affect
3.5 acres of irrigated grass on the levee slope and 1 acre of irrigated grass in the landside easement. This impact would be significant and unavoidable, because there would be a permanent loss of riparian habitat, including wetlands and loss of natural communities and wildlife habitat.
Central Stockton
Calaveras River
Most improvements to Calaveras River levees would be cutoff walls. Construction of these walls would require removal of all vegetation from the top half of the levee and the landside slope. Construction on the Calaveras River levees would result in the removal of 52 acres of woody riparian trees and shrubs.
Vegetation on the lower half of the levee could experience indirect impacts through dust and vibration.
These impacts would be transient and no permanent impacts would be anticipated.
One stretch of improvements on the north levee and one along the south levee, would entail installation of a cutoff wall, slope reshaping and a height fix. Constructing these features would require removal of all vegetation on the top half of the levee and could require removal of vegetation on the lower half of the levee as well. Additionally, this could result in the removal of approximately 1.75 acres of waterside wetlands. Construction would impact up to the entire landside easement.
Construction of levee improvements on the Calaveras River would impact waterside and landside trees and shrubs and wetlands. This impact would be significant and unavoidable, because there would be a permanent loss of 52 acres of riparian habitat, including approximately 7,800 lf of SRA habitat, 1.75 acres of wetlands and loss of natural communities and wildlife habitat.
Stockton Diverting Canal
Alternative 7a does not include any work on the Stockton Diverting Canal. Therefore, there would be no project-related impacts on vegetation in this reach.
Smith Canal
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San Joaquin County, CA Affected Environment and Environmental Consequences Impacts to vegetation from construction of the Smith Canal closure structure would be less than significant within the canal and significant because construction would remove vegetation on the lands at the mouth of the canal. These impacts to vegetation are captured in the subsection below describing vegetation impacts along the SJR in this project reach.
SJR 2,100 feet upstream of the Calaveras River to French Camp Slough Along this reach of the SJR, with the exception of Atherton Island, levee improvements would include a cutoff wall, which would require removal of all vegetation on the upper half of the levee slope. From 2,100 feet upstream of the Calaveras River to the Smith Canal, the levee height would be restored to design height and the level would be raised to address sea level rise. This would require removal of vegetation on the landside of the levee and easement to accommodate construction and the increased width of the levee that would result from increasing the height. From the railroad bridge just upstream of the Port of Stockton to Burns Cutoff, levee slopes, in addition to a cutoff wall, would need to be reshaped and the design height would need to be restored. This would impact all vegetation on the levee slopes and the vegetation in the landside levee easement.
Construction would impact approximately 6,000 lf of SRA and 17 acres of riparian trees and shrubs. This impact would be significant and unavoidable because construction there would be a permanent loss of riparian habitat, including SRA and loss of natural communities and wildlife habitat.