11 Upper Islais Creek Watershed Approach
October 11, 2022 – Commission Update
SFPUC Wastewater Enterprise
101
280
SAN FRANCISCO
SAN MATEO COUNTY
Flood Extent:
5-yr 3-hr storm
2” - 6”
6” - 12”
12” - 36”
>36”
Flood Depth
UPPER ISLAIS
CREEK WATERSHED
LOWER ISLAIS
CREEK WATERSHED
• Think big
• Be creative, all ideas on the table
• Play the long game
• Learn from the past, think about the future, change course if it makes sense • Create policy framework to guide planning & design on the surface • This alternative analysis should take a public policy lens and pose the question:
As this is a large investment, can we deliver more long-term flood resilience, and more ancillary benefits to more
San Franciscans?
Commission Direction from April 2021 Workshop
SFPUC Stormwater Management Approaches & Design Objectives Lower Alemany Area
Stormwater Improvement Project
Eliminates flooding on parcels, sidewalks, and roadways within the project area in the LOS storm and maintains a minimum 2 feet of freeboard in underground conveyance pipes Upper Islais Creek Watershed Approach
Eliminates flooding on parcels, sidewalks, and roadways within the project area in the LOS storm and contains
remaining flows within a designated multi-purpose
floodable greenway
• Completed Alternatives Analysis Report, Finalizing
Conceptual Engineering Report (refinement
of alignment, 10% design, easements,
environmental, traffic, geotechnical)
• Watershed planning, alternatives development
& evaluation, feasibility, costing, scheduling,
community engagement, advanced inter-agency
capital planning
Both approaches’ design objectives are based upon modeled projections generated by the City’s hydrologic and hydraulic model.
WATERSHED APPROACH
101
280
SAN FRANCISCO
SAN MATEO COUNTY
SOAK IT UP
Rain garden
Green roof
Permeable paving
Green street
PROTECT
Floodproofing
Berm, levee, wall
Flood resilient streets
Floodable spaces
SLOW IT DOWN
Tree well storage
Detention basin
Underground storage
Floodable park
The three-part strategy is
designed to manage stormwater
while improving the public realm.
Each scenario is modeled to test
whether the level of service
storm is managed.
101
280
UPPER ISLAIS
CREEK WATERSHED
LOWER ISLAIS
CREEK WATERSHED
SAN FRANCISCO
SAN MATEO COUNTY
Environmental Burden
Least
Highest (SF Planning, 2022)
Environmental Justice
Communities
“Protect” Zone Concept
Nature-based solution
Protects public housing, residential properties, streets, and bike/ped access from flooding during wet weather and delivers a multi-benefit open space during dry weather.
Neighborhood Street
Transform west-bound Alemany into a safe, beautiful, multi- functional neighborhood street protected from flooding and from heavy traffic.
Combined Stormwater & Sanitary
Management Opportunities with MTA, CTA,
Caltrans, Farmer’s Market
1. Extend nature-based solution to maximize
area for combined flow management.
2. Reconfigure sidewalks, crossings, and bike
lanes to improve bicycle and pedestrian safety
and connectivity and make room for combined
flow management.
3. Reconfigure streets and ramps in the maze to
increase safety and make room for combined
flow management.
Alemany Corridor [Part 1]
Alemany Blvd Section – Existing & Concept
Existing
Concept
100-yr: 1 – 2’
5-yr: 0.5 – 1.5’
100-yr: 0.5 - 3’
5-yr: 0 - 2’
CONVEYS COMBINED
FLOWS IN WET
WEATER EVENTS
THAT EXCEED
SYSTEM CAPACITY
Public Access Plan
Public
Access
Plan
Wastewater
Treatment
Wetlands
• Setbacks
• Barriers
CSO
Management
• Storm response
• Signage
• Notifications
Floodable
Spaces
• Public safety
• Public amenities
• In large storms, combined flows can overwhelm our system • The nature-based solution will manage flows in a controlled environment to prioritize public safety
• We will work with stakeholders to create a Public Access Plan that will maximize the benefits of the space while managing levels of public access
• Precedent studies of treatment wetlands, floodable spaces, and CSO management will inform design and operational
parameters to protect public health and safety
• Signage, buffers, barriers, and clear communication are key
Alemany Blvd Section - Existing & LAASIP
Existing
LAASIP
100-yr: 1 – 2’
5-yr: 0.5 – 1.5’
100-yr: 0.5 – 1.5’
5-yr: None
Performance Over Time - Likelihood of flooding 1 foot or more During Key Lifecycle Period of 30 years
Baseline
Watershed
Approach
Conceptual
planning stage
LAASIP
Analysis
performed by
UICWP team
using LAASIP
AAR data
0-25% Less frequent,
larger storms
Frequent,
smaller storms
25-50%
50-75%
75-100%
Likelihood of 1 foot or
more of flooding:
*Note: Multi-storm analysis is
not standard practice for
SFPUC. Design teams do
not typically perform this
analysis.
Nature-Based Solution Before & After
Today Concept
Public Benefits Delivered
Ped. & Bike Safety
86 intersections improved
Heat Resilience
6.7°F cooler during the 2017 heat
wave
Biodiversity
Attracts 11 new bird species
Watershed Community Survey
Top 3 Priorities
1. Storm flooding
2. Pedestrian and bike
safety
3. Air quality
SFPUC worked with San Francisco Estuary Institute to quantify public and environmental benefits resulting from one scenario from the watershed approach.
Public Benefits Analysis Results:
Urban Greening
Canopy cover would increase
along 20 miles of sidewalks
Agency Teammates & Stakeholders
• Mayor’s Office
• MTA, CTA
• Planning
• RPD
• Public Works
• SF Port
• ClimateSF team
• Caltrans
Community Partners
• Friends of Alemany Farm
• Alemany Resident Management Corp.
Neighbors
• +26 organizations (Community Conversations
ongoing)
• +165 community members (survey)
Stakeholder Engagement
2021-2022 Informational Meetings
• SFPUC Commission updates
• Regional Water Quality Control Board
• Wastewater CAC
• Supervisor Mandelman staff (D8)
• Supervisor Ronen (D9)
• Supervisor Ronen (D9) staff meetings
• President Walton staff (D10)
• Supervisor Safai staff (D11)
• Alemany Flea and Farmers Market
• Sea Level Rise Coordinating Committee
• ClimateSF Deputies
Key Benefits & Challenges of the Watershed Approach
Benefits
• Opportunity to engage partners to manage up to the 100-year storm • Supports City policy goals related to transportation, climate resiliency, and public space
• Delivers benefits to more San Franciscans more frequently • Strong alignment with community survey data so far
• Amplifies impact of SFPUC ratepayer dollars by aligning with other public investments
Challenges
• Requires new level of inter-departmental capital planning • Floodable space with combined stormwater and wastewater has novel design, education, and permitting challenges
• Allocation of costs for implementation between departments • Requires high level of engagement with Cal Trans
• Watershed approach will take longer and cost more
SOAK IT UP
Green infrastructure on
streets and parcels
$185Million (high bookend)
15 years
SLOW IT DOWN
Capture and storage
$125Million
6 years
PROTECT Part 1
Nature-based solution
$140Million
Flood resilient street
$90Million
Schedule under development
*Caltrans components & maze not costed or scheduled
Next Steps
1. LAASIP project is the flooding solution for Lower Alemany unless and until an amendment to the Cleanup and Abatement Order is successfully negotiated and all the requisite approvals are obtained
2. Amendment of the Order entails:
a. SFPUC submission to the Regional Water Quality Control Board of a proposal to substitute the Watershed Alternative for the LAASIP project for the flooding solution for the Lower Alemany area by November 10, 2022
b. Successful negotiation of an agreement-in-principle to amend the Order, including concurrence on the project design and schedule
c. Commission recommendation to amend the Order consistent with the agreement-in- principle
d. Board of Supervisors approval to amend the Order consistent with the agreement-in- principle
e. Regional Board public hearing and Board issuance of amended Order