Santa Clara Valley Water District
File No.: 22-0207 Agenda Date: 2/15/2022
Item No.: 2.2.
BOARD AGENDA MEMORANDUM
SUBJECT:..Title
Anderson Dam Seismic Retrofit Project Status Update.
RECOMMENDATION:..Recommendation
Receive information on the Anderson Dam Seismic Retrofit Project.
SUMMARY:
The Anderson Dam Seismic Retrofit Project (ADSRP) will correct dam seismic deficiencies and otherwise meet all current Federal Energy Regulatory Commission (FERC) and California Department of Water Resources, Division of Safety of Dams (DSOD) dam safety design standards.
The full reservoir capacity will be restored upon completion of the Project.
Throughout 2019 to early 2020, project staff and consultants had been progressing with preparation of 90% design plans and specifications and supporting environmental and permitting documents. On February 20, 2020, the Santa Clara Valley Water District (Valley Water) received a letter order from FERC to immediately implement ADSRP-related interim risk reduction measures.
Valley Water is undertaking the Anderson Dam Federal Energy Regulatory Commission Order Compliance Project (FOCP) as a result of the February 20, 2020 directive from FERC to implement interim risk reduction measures at Anderson Dam. One of those measures is the Anderson Dam Tunnel Project (ADTP). The ADTP will construct a diversion system to augment the existing outlet, which will consist of a new diversion tunnel, an outlet structure, a micro-tunnel lake tap, and modifications to Coyote Creek just downstream of the base of the dam. The ADTP also includes reservoir bank and rim stability improvements and existing intake structure modification.
On April 27, 2021, Valley Water’s Board of Directors awarded the construction contract for the Anderson Dam Tunnel Project (ADTP) to the top ranked best value proposer, Flatiron West, Inc., in the sum of $161,140,321 and approved a contingency amount of $40,000,000 (25% of the contract price).
A second FOCP measure is the Cross Valley Pipeline Extension Project (CVPEP). The CVPEP entails constructing a new pipeline to convey imported water from the Cross Valley Pipeline to Coyote Creek to supplement flows during the construction of the ADSRP downstream of Ogier Ponds. The Project scope includes constructing an outfall which will include an energy dissipator, and Santa Clara Valley Water District Printed on 2/10/2022Page 1 of 2 powered by Legistar™
File No.:22-0207 Agenda Date:2/15/2022
Item No.:2.2.
creek bank improvements.
On November 9, 2021, Valley Water’s Board of Directors awarded the construction contract for the CVPEP to the lowest responsible, responsive bidder, Garney Pacific, Inc., in the sum of $12,867,059 and approved a contingency amount of $1,930,059 (15% of the contract price).
ENVIRONMENTAL JUSTICE IMPACT:
There are no Environmental Justice impacts associated with this item.
FINANCIAL IMPACT:
Although there is no financial impact associated with this item, the Total Project Cost of the ADSRP has increased by $589 million from $647 million (FY2022-FY26 CIP) to $1.236 billion (all dollar values referenced are inflated). Broadly, the reasons for this cost increase include the extension of the project construction schedule from 5 years to 10 years, additional environmental and permitting related costs, design changes, dam safety regulator mandated modifications and the previous undervaluation of Anderson Dam Tunnel Project cost. Further details are explained in the presentation (Attachment 1).
CEQA:
The recommended action does not constitute a project under CEQA because it does not have a potential for resulting in direct or reasonably foreseeable indirect physical change in the environment.
ATTACHMENTS:
Attachment 1: PowerPoint
UNCLASSIFIED MANAGER:..Manager
Chris Hakes, 408-630-3796
Santa Clara Valley Water District Printed on 2/10/2022Page 2 of 2 powered by Legistar™
valleywater.org
1 Anderson Dam Seismic Retrofit Project
February 15, 2022
Attachment 1
valleywater.org
2 Anderson Dam Seismic Retrofit Project
October 28, 2021
Agenda
Background
Project Cost
Current Status
Attachment 1
valleywater.org
3 Background
• Anderson Dam forms Anderson Reservoir, holding 90,000 acre feet o
f water when full and the largest of Valley Water’s reservoirs. • In 2012, following a seismic stability analysis, Valley Water began pl
ans to retrofit the dam to meet current safety standards, creating the Anderson Dam Seismic Retrofit Project (ADSRP).
• On February 20, 2020, the Federal Energy Regulatory Commission (
FERC) issued an order to Valley Water to undertake early implementation interim risk reduction measures associated with ADSRP immediately.
Attachment 1
valleywater.org
4 ADSRPAnderson Dam Federal Energy Regulatory
Commission Order Compliance Projects (FOCP)
Anderson
Dam Tunnel
Project Coyote Percolation
Pond Dam
Replacement
Coyote
Creek Flood
Protection
Measures
Coyote Creek
Stream
Augmentation Fish
Protection
Measure
Cross Valley
Pipeline Extension
• Seismic retrofit of dam embankment
• C
onstruction of new higher capacity
outlet tunnel and outlet works
• Replacement of concrete spillway
and raising wall height 9-feet to
safely discharge large storm flows
• Increase dam crest height 7-feet
Attachment 1
valleywater.org
5 High Level Outlet Pipe
Anderson Dam Seismic Retrofit Project Components
Remove all liquefiable material and
reconstruct embankment
Replace
Spillway
Low Level Outlet Pipe
Temporary Diversion System
Attachment 1
valleywater.org
6 FERC Directive: Risk Reduction Measures
2. Take all necessary measures to safely prepare and drain the reservoir to El. 488’
3. Oct. 1 - Begin draining reservoir to dead pool (El. 488’)
4. Develop plan to maintain dead pool elevation in event of significant inflow
5. Expedite design and construction of new Outlet Tunnel
6. Secure permits and complete design of larger Seismic Retrofit Project
1. Lower reservoir to new restriction (El. 565’)
Attachment 1
valleywater.org
7 Anderson Reservoir at 3% Capacity - Map
Attachment 1
valleywater.org
8 Anderson Dewatered
Attachment 1
valleywater.org
9 Anderson Dam Seismic Retrofit Project
October 28, 2021
Agenda
Background
Project Cost
Current Status
Attachment 1
valleywater.org
10 Additional
Environmental/Permit
Related Costs,
$128
Extending Project
from 5 Years to 10
Years, $340
Valley Water
Controlled Design
Options, $75
DAM Safety Regulator
Mandated
Modifications, $20
ADTP Undervaluation,
$26
• FY 21: $576M (Inflated)
• FY 22: $647M (Inflated)
• FY 23: $1.236B (Inflated)
Anderson Dam Seismic Retrofit Project - Cost Increases
($ in millions, estimated inflated values)
+ $589M
Attachment 1
valleywater.org
11 Anderson Dam Seismic Retrofit Project
October 28, 2021
Agenda
Background
Project Cost
Current Status
Attachment 1
valleywater.org
12 • Reservoir Drawdown to Deadpool and Maintain Level at Deadpool – C omplete • Anderson Dam Tunnel Project (ADTP) Construction – On-go ing • Anderson Dam Tunnel Operation and Maintenance – P ost ADTP Construction • Bank and Rim Stability Improvements ( Included in ADTP) • Existing Intake Structure Modifications ( Included in ADTP) • Creek Channel and Bank Erosion Control Modifications ( Included in ADTP) • Imported Water Releases and Cross Valley Pipeline Extension –On-go ing • Coyote Percolation Dam Replacement – I n Design
• Coyote Creek Flood Management Measures – I n Design
• Steelhead Fish Avoidance and Minimization Measures – I n Design • Implementation of Additional Project Specific Avoidance and Minimization M
easures - In Planning/Design
FOCP Elements - Current Status
Attachment 1
valleywater.org
13 Typical Equipment
Attachment 1
valleywater.org
14 Tunneling Equipment
Attachment 1
valleywater.org
15 ADTP Potential Impacts
Potential impacts include:
• After storm events, the water level in the reservoir will rise temporarily • Increased flows in Coyote Creek, downstream of the dam, after storm events • Noise from construction equipment (large diesel engines) and backup alarms • Work activities will mainly be Monday through Friday during the daytime, but s
ome Saturdays may be required
• Smells caused by elevated levels of algae in the summer.
Alg
al blooms can deplete oxygen levels in the water and produce hydrogen sulfide (rotten egg taste and odor)
Attachment 1
valleywater.org
16 Project Schedule
Attachment 1
Regulatory Agencies
Federal
• FERC - F ederal Energy Regulatory
Commission lead on design and
environmental
• USACE - U
S Army Corps of
Engineers
• US Fish and Wildlife Service
• US Environmental Protection
A
gency
• National Oceanic and Atmospheric
As
sociation - NOAA
• National Marine Fisheries
S
ervice - NMFS
State
• Division of Safety of Dams – D SOD
• California Office of Historic Preservation
(
SHPO)
• California Department of Fish and Wildlife
• State Water Resources Control Board
• Regional Water Quality Control Board
County
• Valley Habitat Agency
• Santa Clara County Parks
Cities of:
• Morgan Hill
• Gilroy
• San José
Attachment 1
valleywater.org
18 Attachment 1