OAAC ADAPT: Oakland-Alameda Adaptation Projects
Oakland Alameda Multi-Hazard
Adaptation and Community Benefits
Project
Technical Report
December 2023
Prepared For
Oakland Alameda Adaptation Committee
Prepared By
Pathways Climate Institute
PRIMARY AUTHORS
Kris May, PhD PE
Lindsay Luchinsky, MSc
Meagan Brown, MSc
Michael Mak, PE
Acknowledgements
With support from CMG Landscape Architecture, Moffatt & Nichol, Schaaf and Wheeler, Environmental Science Associates, and NHA Advisors, .
and the City of Alameda, City of Oakland, Port of Oakland, East Bay Regional Park District, California Department of Transportation and Community Partners: , Hood Planner , Community Action for a Sustainable Alameda and Greenbelt Alliance.
Disclaimer
This report was produced to support a Building Resilient Infrastructure and Communities (BRIC) 2023 Grant Application for the Federal Emergency Management Administration (FEMA). The materials and alternatives referenced, cited, and included within this report may change as the Oakland - Alameda Adaptation Committee engages with the surrounding communities and continues making progress towards implementation.
Suggested Citation
May, CL, Luchinsky, L, Brown, M, Mak, M (2023). Oakland -Alameda Adaptation Projects FEMA BRIC Grant Application Technical Report. Prepared for the City of Alameda, CA.
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Table of Contents
1 INTRODUCTION ................................................................................................................................ 1 2 PROJECT AREA ................................................................................................................................ 1 3 FLOOD HAZARDS ............................................................................................................................. 5
3.1 THE AIRPORT AND BAY FARM ISLAND ............................................................................................................ 5
3.2 EAST OAKLAND (COLUMBIA GARDENS) ......................................................................................................... 7
3.3 ADDITIONAL BAY FARM ISLAND FLOOD RISKS ................................................................................................ 9
3.3.1 Lagoon Stormwater Flood Risk Mitigation ......................................................................................................... 9
3.3.2 Northern Bay Farm Island Shoreline Improvements ........................................................................................... 9 4 PROJECT BENEFITING AREA ....................................................................................................... 11 5 MITIGATION ACTIONS .................................................................................................................... 12
5.1 THE AIRPORT AND BAY FARM ISLAND .......................................................................................................... 13
5.1.1 Doolittle Drive (State Highway 61) ................................................................................................................... 13
5.1.2 Lagoon and Northern Shoreline ....................................................................................................................... 17
5.1.3 Veterans Court ................................................................................................................................................. 18
5.2 EAST OAKLAND (COLUMBIAN GARDENS) ..................................................................................................... 19
5.2.1 Stormwater Flooding ....................................................................................................................................... 19
5.2.2 Green Instructure ............................................................................................................................................. 22
5.2.3 San Leandro Creek Tidal Flooding .................................................................................................................... 24
5.3 ADDITIONAL BAY FARM ISLAND FLOOD RISK REDUCTION .............................................................................. 24
5.3.1 Lagoon Stormwater Flood Risk Mitigation ....................................................................................................... 24
5.3.2 Northern Bay Farm Island Shoreline Improvements ......................................................................................... 25
5.4 WETLAND ENHANCEMENT FOR FLOOD RISK REDUCTION .............................................................................. 26 6 LITERATURE CITED ....................................................................................................................... 30
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Tables
TABLE 1. DOOLITTLE DRIVE (STATE HIGHWAY 61) CONSTRUCTION COSTS ............................................................... 16 TABLE 2. LAGOON AND NORTHERN SHORELINE CONSTRUCTION COSTS ................................................................... 17 TABLE 3. VETERANS COURT CONSTRUCTION COSTS .............................................................................................. 19 TABLE 4. COLUMBIA GARDENS STORMWATER FLOOD RISK REDUCTION CONSTRUCTION COSTS ................................ 20 TABLE 5. COLUMBIA GARDENS GREEN INFRASTRUCTURE CONSTRUCTION COSTS .................................................... 23 TABLE 6. SAN LEANDRO CREEK CONSTRUCTION COSTS ......................................................................................... 24 TABLE 7. LAGOON STORMWATER CONSTRUCTION COSTS ....................................................................................... 25 TABLE 8. SAN LEANDRO BAY WETLAND AREA AND THIN SEDIMENT PLACEMENT COST ESTIMATE .............................. 29
Figures
FIGURE 1. SAN FRANCISCO BAY AND SAN LEANDRO BAY .......................................................................................... 2 FIGURE 2 PROJECT AREA AND FEMA COMMUNITY DISASTER RESILIENCE ZONE ........................................................ 3 FIGURE 3. PROJECT AREAS IN FEMA EFFECTIVE FLOOD INSURANCE RATE MAP ........................................................ 7 FIGURE 4. SHORELINE OVERTOPPING LOCATIONS .................................................................................................... 7 FIGURE 5. EAST OAKLAND’S COLUMBIA GARDENS IN FEMA’S FLOOD INSURANCE RATE MAP ...................................... 8 FIGURE 6. COLUMBIA GARDENS OVERTOPPING LOCATIONS ...................................................................................... 9 FIGURE 7. PROJECT BENEFITING AREA .................................................................................................................. 12 FIGURE 8 FLOOD RISK MITIGATION ACTIONS .......................................................................................................... 13 FIGURE 9. SHEET PILE FLOODWALL (OUTBOARD OF DOOLITTLE DRIVE) EXAMPLE CROSS SECTION ........................... 16 FIGURE 10. VETERANS COURT SHORELINE REALIGNMENT AND FLOOD RISK MITIGATION ACTIONS ............................. 18 FIGURE 11. COLUMBIA GARDENS FLOOD RISK MITIGATION ..................................................................................... 20 FIGURE 12. COLUMBIA GARDENS GREEN INFRASTRUCTURE PLAN ........................................................................... 22 FIGURE 13. COLUMBIA GARDEN BIORETENTION PLANTERS EXAMPLE....................................................................... 23 FIGURE 14. WETLAND ENHANCEMENT AND FLOOD RISK REDUCTION LOCATIONS ...................................................... 28
Photos
PHOTO 1. LOW-LYING DOOLITTLE DRIVE (STATE HIGHWAY 61) ADJACENT TO SAN LEANDRO BAY ................................ 4 PHOTO 2. BAY FARM LAGOON TIDE GATE ................................................................................................................ 9 PHOTO 3. BAY FARM ISLAND TRAIL ....................................................................................................................... 10 PHOTO 4. BAY FARM TRAIL EROSION .................................................................................................................... 11 PHOTO 5. FOSTER CITY BAY TRAIL BEFORE PROJECT ............................................................................................ 14
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PHOTO 6. FOSTER CITY BAY TRAIL AFTER PROJECT .............................................................................................. 15 PHOTO 7. HAMILTON AIRFIELD WETLAND RESTORATION, NOVATO, CALIFORNIA ....................................................... 26
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Acronyms / Abbreviations
Acronym Signification
Airport Oakland International Airport
BRIC Building Resilient Infrastructure and Communities
Caltrans California Department of Transportation
CDRZ Community Disaster Resilience Zone
EBRPD East Bay Regional Park District
FEMA Federal Emergency Management Agency
FIRM Flood Insurance Rate Map
MHHW mean higher high water
OAAC Oakland Alameda Adaptation Committee
Port Port of Oakland
SFHA Special Flood Hazard Area
SLR sea level rise
SWL stillwater level
TWL total water level
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1 Introduction
The Oakland Alameda Multi -Hazard Adaptation and Community Benefits Project will reduce existing and future flood risk within the Oakland International Airport (the Airport) Community Disaster Resilience Zone (CDRZ) and will address existing and future flood risks along San Leandro Creek within east Oakland underserved communities. The project includes flood mitigation elements that will remove the Airport, and communities within the Cities of O akland and Alameda from the Federal Emergency Management Agency (FEMA) Special Flood Hazard Area (SFHA) while also protecting important transportation corridors, enhancing access to the San Leandro Bay shoreline, and providing adaptive capacity and resilience for future sea level rise.
This project requires collaboration across multiple jurisdictions due to the connected nature of coastal flooding that occurs when coastal waters overtop multiple locations along the shoreline. Projects implemented within a single jurisdiction would be insufficient to remove the project area from the FEMA SFHA. A multi -hazard, multi -jurisdictional adaptation project is required to address the complex, compounding, and co -mingled existing and future flood hazards across the Ci ties of Alameda and Oakland and the Airport and within the CDRZ.
2 Project Area
San Leandro Bay is located on the western shoreline of San Francisco Bay in the County of Alameda (Figure 1), nestled between the Cities of Alameda and Oakland and the Airport where San Leandro Creek enters the bay (Figure 2). San Leandro Bay is a sheltered estuary with high-quality marsh habitat for the endangered California Ridgway rail ( Rallus obsoletus obsoletus ) and the salt marsh harvest mouse (Reithrodontomys raviventris). San Leandro Bay is surrounded by a mix of marsh habitat, the Airport, industrial areas, transportation corridors, and residential areas.
A portion of the City of Oakland, including the Airport, are is located within a CDRZ, a geographic area that FEMA i dentified as most at -risk and in-need from natural disasters and climate change (FEMA 2023a). The CDRZ is identified listed as disadvantaged by the White House Council on Environmental Quality Climate and Economic Justice Screening Tool. The Airport, and much of the surrounding area, is also over the 99th percentile for FEMA’s National Risk Index (NRI), highlighting its very high risk to natural hazards (FEMA 2023b).
The Airport opened in 1927 with the world's longest runway and it continues to serve as one of the three international airports serving the larger San Francisco Bay Area. The Airport has 14 airlines operating out of its two terminals and nine rental car agencies as well as supporting businesses in the Airport CDRZ. The Airport saw 13.3 million passengers pass through its terminals in 2019 and is expected to grow beyond 20 million over the next decade (Port of Oakland 2021). Airport employees mainly live in the adjacent cities of Oakland (435,000 population) and Alameda (76,000 population) , with east Oakland (95,000 population) having the highest concentration of Airport workers, along with other areas in the far East Bay, which often have a high Nati onal Risk Index, also benefitting from Airport employment.
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Figure 1. San Francisco Bay and San Leandro Bay
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Figure 2 Project Area and FEMA Community Disaster Resilience Zone
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State Highway 61 (Doolittle D rive) is located between the Airport and San Leandro Bay and is the primary throroughfare for accessing the Airport service industries. Doolittle Drive is a critical evacuation route for residents on Bay Farm Island in the event of an earthquake, tsunami, severe flood, or other dsaster. Owned and operated by the California Department of Transportaiton, Doolittle Drive is a busy and low-lying roadway that experiences coastal overtopping during extreme high tides and coastal storm surge events (Photo 1).
Underserved and marginalized east Oakland communities are located east of Doolittle Drive and along San Leandro Creek with the CDRZ. Migrations from the American south starting in 1914 and from the adjacent I-580 freeway construction in 1947 caused east Oakland to become a predominately Black and now Latinx community due to the federal policy of redlining, which began in 1934, adjacent industrial jobs , and restrictive covenants in other neighborhoods . Currently, east Oakland residents experience a lower life expectancy at 72 years, higher rates of obesity at 32 percent and 48 percent for children and lack of access to healthy food and affordable housing. Due to the adjacent I-880 freeway, which was built in 1958, higher rates of asthma and soot impact these communities. Consequently, East Oakland is recognized as a Justice40 community and currently has a median household income of about $40,000 with a disproportionately Black (37%) and Other/Latino (32%) population.
Bay Farm Island is located within the City of Alameda, directly adjacent to the Airport. Bay Farm Island includes the Chuck Corica Gulf Complex, office and retain complexes, and approximately 14,600 residents. A portion of the San Francisco Bay Trail wraps around the bay-edge of Bay Farm Island, and along Doolittle Drive, providing public access to the bay and recreation. The San Francisco Bay Trail within Alameda County is managed by the East Bay Regional Park District (EBRPD).
Photo Credit: Sergio Ruiz, Flickr 2019
Photo 1. Low-lying Doolittle Drive (State Highway 61) adjacent to San Leandro Bay Commented [LL1]: Lindsay to rework this sentence
Commented [LL2]: Lindsay to rework this sentence
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3 Flood Hazards
San Francisco Bay is the largest estuary in the western U.S., with a contributing watershed that includes nearly 40% of California, and substantial freshwater flows entering through the Sacramento River. The 300-foot-deep Golden Gate inlet connects the Bay with the Pacific Ocean, and the tides, ocean-driven swells, and extreme ocean water levels all enter the Bay through this single inlet. The large expanse of the Bay and the complex topography surrounding the Bay can transform storm -driven winds in a multitude of directions depending on the primary driver of the onshore or offshore winds or the track of the large storm system descending on the Bay Area. The water levels and wave heights of the Bay exhibit a high degree of variability driven by many factors, including the bathymetry, astronomical and oceanic cycles, windspeeds and direction, and atmospheric events (May et al. 2016b). In the Bay, no single storm event produces the highest water level and highest wave hazard along the entire shoreline (May et al. 2016a).
Although large wave hazards (e.g., up to 5 feet) can occur on the San Francisco Bay side of the Airport, San Leandro Bay is protected from large waves due to its sheltered location and much smaller size.
FEMA analyzed coastal water levels and wave hazards for the entire San Francisco Bay shoreline, resulting in updated Flood Insurance Rate Maps (FIRMs) for the nine Bay Area counties, including the County of Alameda (DHI 2011; FEMA 2018). Figure 3 shows FEMA SFHA within the project area. The Airport’s levee along San Francisco Bay is accredited, allowing a portion of the Airport to be removed from the SFHA as an area with reduced risk protected by a levee (see the hatched area on Figure 3).
This project seeks to mitigate the flood ri sks within the CDRZ, which includes flood risk mitigationng flood risks for the Airport and Bay Farm Island , and mitigating flooding flood risks , as w ell for East Oakland’s Columbia Gardens neighbood. Additional mitigation on Bay Farm Island will enhance the effectiveness and long-term resilience of the project.
3.1 The Airport and Bay Farm Island
The Airport’s North Field and supporting industries remain within the FEMA SFHA. Removing this area from the FEMA SFHA will require addressing multiple areas where coastal floodwaters can overtop the shoreline (Figure 4):
• Doolittle Drive (State Highway 61) : Doolittle Road Drive is low -lying along its entire length adjacent to the Airport’s North Field and supporting industries. Overtopping can occur at multiple locations along Doolittle Drive. Fringing marsh is located on the bayside of Doolittle Drive for much of its length within the project area, although a portion is armored w ith rock revetment.
The Martin Luther King Jr. Shoreline Park, with parking, a kayak/boat launch, and open space, is located along Doolittle Drive between Langley and Grumman Streets. Improvements along Doolittle Drive to address flooding will require coor dination between the Airport, Caltrans, and EBRPD.
• Lagoon Shoreline: At the northern end of the Lagoon on Bay Farm Island within the City of Alameda’s jurisditionjurisdiction, where the shoreline and tide gate structure are low spots along the existing shoreline.
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• Veterans Court: Floodwaters can overtop the shoreline near the touchdown of the Bay Farm Bridge (State Highway 61), between the closed Alameda landfill and Veterans Court, within the City of Alameda’s JurisidtionJurisdiction. The shoreline includes an aging seawall, rock riprap, and fringing marsh habitat.
Coastal overtopping along Doolittle Drive, and at the Lagoon Shoreline and Veterans Court must all be addressed to mitigate flood risks along Doolittle Drive and the Airport. The Port of Oakland (which owns the Airport) completed a two- dimensional hydrodynamic modeling study to better assess stormwater and coastal flood risks and mitigation strategies . The Port determined that, in additional to mitigation elements along Doolittle Drive, the Airport would either have to construct a floodwall along much of Harbor Bay Parkway, from Doolittle Drive to Ron Cowan Parkway to address the flood hazards coming from the City of Alameda into the Airport property, or collaborate with the City of Alameda to mitigate the coastal overtopping occurring at the Lagoon Shoreline and Veterans Court (Port of Oakland 2023).
An earlier study completed by the San Francisco Bay Conservation and Development Commission as part of the Adapting to Rising Tides program agrees with this finding (AECOM 2014).
The converse of this equation is also true. The City of Alameda can mitigate the flood risks at the Lagoon and Veterans Court low points, but they cannot remove the Bay Farm Island residents that live along the Bay Farm Lagoon from the FEMA SFHA until the flooding along Doolittle Drive, outside of their jurisdiction, is also mitigated (AECOM 2014). The most cost -effective solution to mitigate flood risks within these areas requires coordination between both entities (Port of Oakland 2023) . This coordination is occurring through the Oakland-Alameda Adaptation Committee.
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Source: (FEMA 2023c)
Figure 3. Project Areas in FEMA Effective Flood Insurance Rate Map
Source: (FEMA 2023c)
Figure 4. Shoreline Overtopping Locations
3.2 East Oakland (Columbia Gardens)
In addition to the Airport and Bay Farm Island, the Columbia Gardens neighborhood is mapped within FEMA’s SFHA (Figure 5). This area experiences regular flooding during heavy rainfall events, due to overtopping along a drainage channel adjacent to the neighborhood, and flooding during extreme bay (coastal) water levels due to overtopping along San Leandro Creek ( Figure 6). This neighborhood is low-income and recognized as a Justice 40 community with a median annual household income of about $40,000 and is disproportionately Black (37%) and Other/Latino. Removing this community from FEMA’s SFHA requires addressing both sources of flooding (City of Oakland 2022).
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Source: (FEMA 2023c)
Figure 5. East Oakland’s Columbia Gardens in FEMA’s Flood Insurance Rate Map
Source: Google Earth Aerial Imagery
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Figure 6. Columbia Gardens Overtopping Locations
3.3 Additional Bay Farm Island Flood Risks
3.3.1 Lagoon Stormwater Flood Risk Mitigation
A system of lagoons is used to manage stormwater and reduce rainfall-driven flood risks on Bay Farm Island. Bay waters are pumped into the Bay Farm lagoon on the San Francisco Bay edge, and water flows via gravity through the lagoon and out a tide gate at the Lagoon overtopping point shown on Figure 4. The lagoons provide public access and recreation benefits, with a network of trails and playgrounds along the lagoon shoreline. Prior to significant rainfall events, the lagoons are drawn down (i.e.., the water level of the lagoon is lowered) by gravity flows by opening the tide gate when Bay water levels are low (Photo 2). Drawing down the lagoon provides stormwater flood storage capacity, and Bay Farm Island’s stormwater network largely drain to the lagoon system. Raising the shoreline elevation of the Lagoon overtopping low point will require enhancements to the lagoon operations to maintain the stormwater flood risk reduction capacity of the system.
Photo Credit: Kris May
Photo 2. Bay Farm Lagoon Tide Gate
3.3.2 Northern Bay Farm Island Shoreline Improvements
The San Francisco Bay trail wraps around Bay Farm Island, providing recreation and public access to the bay (Photo 3). However, portions of the shoreline are experiencing wave- and storm-driven erosion,
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threatening the trail, and reducing the flood risk reduction capacity of the shoreline. In some areas, the shoreline has eroded by up to 30 feet, placing former public benches and irrigation lines in areas of open bay water (Photo 4). Addressing this ongoing hazard will improve the overall resilience of the flood risk mitigation actions on Bay Farm Island.
Photo Credit: Kris May
Photo 3. Bay Farm Island Trail
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Photo Credit: Kris May
Photo 4. Bay Farm Trail Erosion
4 Project Benefiting Area
The project benefiting area includes the CDRZ , and the area around the Bay Farm Lagoon that wou ld be removed from the FEMA SFHA. The Chuck Corica Golf Complex is not included within the project benefitting area. The Golf Complex has raised grades to mitigate potential flood hazards. These activities occurred after 2018 FIRMs became effective. The residential homes in the vicinity of Maitland Drive are not included within the project benefiting area. This area is low lying, with ground elevations that are 5 to 10 feet below the surrounding areas (at about mean sea level or below). This area would still experience stormwater driven flood risks after implementation of this project.
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Figure 7. Project Benefiting Area
5 Mitigation Actions
Addressing existing and future flood risks requires a coordinated, multi-jurisdictional effort between the Cities of Oakland and Alameda, the Port of Oakland, Caltrans, EBRPD, community-based organizations (CBOs) including Tribal partners, and other local and state agencies. Together, these entities are collaborating to reduce existing and future flood risks with hybrid nature- based solutions and habitat enhancements along both estuarine and riverine shorelines. Led by the City of Alameda, the group is called the Oakland Alameda Adaptation Committee (OAAC). OAAC is paying CBOs as Community Partners to bring much -needed benefits to, and build capability and capacity in, underserved and marginalized communities within the project area.
This project includes mitigation actions that were developed through separate planning processes by the Cities of Alameda and Oakland, the Port of Oakland, and the EBRPD. The OAAC has brought these mitigation actions together as one cohesive solution to mitigate existing flood risks within the CDRZ, as well as two feet of future sea level rise to provide future clim ate change resilience. Combining these projects together reduces project costs, provides opportunities to enhance project benefits, and maximizes the likelihood of achieving a comprehensive flood risk reduction solution.
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The following sections describe the mitigation actions included within the overall project:
1. Doolittle Drive
2. Lagoon and Northern Bay Farm Shoreline
3. Veterans Court
4. Columbian Garden
5. Lagoon
6. Wetland Enhancements to Maintain and Reduce Flood Risks as Sea Levels Rise
Source: Google Earth Aerial Imagery
Figure 8 Flood Risk Mitigation Actions
5.1 The Airport and Bay Farm Island
5.1.1 Doolittle Drive (State Highway 61)
The Port of Oakland analyzed for project alignments to mitigate coastal overtopping along Doolittle Drive (Item 1 , Figure 8), as well as three potential flood risk reduction measures (i.e., sheet pile floodwall, earthen levee, and a concrete floodwall). The concrete floodwall was about twice the total costs of the sheet pile floodwall and earthen levee measures, respectively. The sheet pile floodwall and earthen have comparable total costs; however, the earthen levee required a much larger project
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footprint. Constructing an earthen levee along Doolittle Drive would either impact State Highway 61, requiring roadway re-alignments to maintain traffic flow, or the earthen levee would require bay fill within San Leandro Bay, including filling the fringing marsh habitat which serves two endangered species, the California Ridgeway rail and salt marsh harvest mouse.
The sheet pile flood wall is a cost -effective solution and requires a minimal project footprint (i.e., horizontal cross section). The sheet pile floodwall would be constructed between Doolittle Drive and San Leandro Bay, adjacent to the San Francisco Bay trail , providing an opportunity to increase safety for pedestrians and bicyclists. The flood walls’ aesthetics would be enhanced with the use of a concrete cap. This solution is similar to that used by Foster City, California on the eastern shore of San Francisco Bay to mitigat e flood risks ( Photo 5 and Photo 6). The Foster City project also provides a recent comparable for construction costs (Foster City 2016, 2020a, b).
Photo Credit: San Mateo Daily Journal
Photo 5. Foster City Bay Trail Before Project
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Photo Credit: Riex, Flickr User
Photo 6. Foster City Bay Trail After Project
Source: (Port of Oakland 2023)
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Figure 9. Sheet Pile Floodwall (Outboard of Doolittle Drive) Example Cross Section Table 1. Doolittle Drive (State Highway 61) Construction Costs Item Length (feet) Cost Unit Construction Cost
Sheet Pile Floodwall 5,000 $1,095 LF $5,475,000
Concrete Cap 5,000 $300 LF $1,500,000
Flood Break Structure (1) 60 $12,000 LF $720,000
Subtotal $7,695,000
40% Soft Costs $3,078,000
Total Construction Costs $10,773,000
Maintenance (15%, 35
years)
$1,615,950
Source: (Foster City 2020a; Port of Oakland 2023)
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5.1.2 Lagoon and Northern Shoreline
The northern Bay Farm shoreline, from Veterans Court to the northwest corner, would be improved by raising the shoreline elevation and the associated Bay Train with an 18- foot-wide earthen levee (Item 2, Figure 8). In areas where erosion is occurring, existing r ock riprap will be re-used on site, and ecological armoring will be used to augment the existing rock slop protection. The Port of San Diego used bio- enhanced concrete to construct ecological enhancements of riprap areas protecting the shoreline adjacent to the San Diego International Airport (Krasna and Rella 2023). In addition to erosion and slope protection, the project provided a solution that mimicked natural rock pools and provided habitat that increased shoreline biodiversity (Krasna and Rella 2023) . The Port of San Francisco is currently conducting a living seawall pilot study, with a goal of enhancing biodiversity along coastal and marine infrastructure (USACE 2024). The use of engineering with nature to mimic natural processes and increase the resilience of flood protection infrastructure is a growing practice within FEMA and USACE (Bridges et al. 2021; Holmes et al. 2022; FEMA 2023d).
Table 2. Lagoon and Northern Shoreline Construction Costs Item Length (feet) Cost Unit Construction Cost
Earthen Levee 4,500 $990 LF $4,455,000
Ecological Armoring 2,000 $400 LF $800,000
Subtotal $5,255,000
40% Soft Costs $2,102,000
Total Construction Costs $7,357,000
Maintenance (15%, 35
years)
$1,103,550
Source: Moffatt & Nichol 2023
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5.1.3 Veterans Court
In Veterans Court (Item 3, Figure 8), the existing cul-de-sac will be moved about 250 feet to the south, providing space to expand the wetland area in the relatively sheltered cove surrounding the Bay Farm Bridge (SR 61) touchdown on Bay Farm Island (Figure 10). And earthen levee with 18- foot-wide Bay Train would be constructed along the existing Bay Train alignment, between the Harbor Bay Club tennis course and San Leandro Bay.
This alternative will require reconstructing the pedestrian and bike path that passes under the Bay Farm Bridge, connecting the Bay Train from the closed landfall to the east to the Veterans Court area. This cost is not included within the FEMA BRIC grant application.
Figure 10. Veterans Court Shoreline Realignment and Flood Risk Mitigation Actions
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Table 3. Veterans Court Construction Costs
Item Length (feet) Cost Unit Construction Cost
Earthen Levee 800 $1,100 LF $880,00
Ecological Armoring 400 $400 LF $396,000
Wetland Expansion 0.5 (acre) $1,000,000 acre $500,000
Subtotal $1,776,000
40% Soft Costs $710,400
Total Construction Costs $2,486,400
Maintenance (15%, 35
years)
$372,960
5.2 East Oakland (Columbian Gardens)
The mitigation actions described below in Section 5.2.1 and Section 0 are recommended for stormwater flood risk reduction and air quality benefits. The mitigation action described in Section 5.2.3 would address overtopping along San Leandro Creek that could impact the Columbia Gardens neighborhood; however, the private landowner who owns the property may be amenable to working with the City of Oakland on the shoreline improvements.
5.2.1 Stormwater Flooding
The City of Oakland evaluated a range of alternatives to mitigate the stormwater flooding in the Columbia Gardens nei ghborhood (City of Oakland 2022) . This area was found to have maintenance deficiencies related to debris collection, sediment deposition, and vegetation overgrowth. However, even with improved maintenance, the conveyance capacity of the stormwater pipes and drainage channel was determined to be insufficient and a major source of flood risk. The City of Oakland performed detailed hydrologic and hydraulic modeling to develop and evaluate alternatives (City of Oakland 2022).
The preferred alternative includes constructing a bypass dual 18” storm drainpipe system along Cairo Road that will work with the existing storm drain system and driver flows into the channel. The drainage channel would be deepened to increase its capacity, and sheet pile walls would be constructed on either side of the channel to maintain the channel banks and reduce the likelihood of channel overtopping during extreme rainfall events (City of O akland 2022). The channel would be deepened enough to allow unmaintained channel bottom overgrowth and vegetation, while still maintaining the
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required capacity for flood risk reduction. Allowing vegetation to remain within the channel is preferred over maintaining a clear , earthen channel bottom. Although this preferred option has a higher initial capital cost, the longer-term maintenance for vegetation overgrowth would be reduced; and there would be a higher likelihood that the channel would provide sufficient flood risk reduction during heavy rainfall events for the adjacent underserved community.
Figure 11. Columbian Gardens Flood Risk Mitigation
Table 4. Columbian Gardens Stormwater Flood Risk Reduction Construction Costs Item Length (feet) Cost Unit Construction Cost
Dual 18" RCPs 475 $1,460 LF $693,500
Channel Deepening 700 $1,000 LF $700,000
Sheet Pile Flood Walls 1,400 $1,995 LF $2,793,000
Subtotal $4,186,500
40% Soft Costs $1,674,600
Total Construction Costs $5,861,100
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Maintenance (15%, 35
years)
$879,165
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5.2.2 Green Instructure
Columbian Gardens would also benefit from flow -thru bioretention areas (about 6 feet by 35 feet) to provide water quality treatment and stormwater retention (Figure 12 and Figure 13). The bioretention areas can include tree plantings to improve air quality and reduce the heat island effect during high heat days. The neighborhood is directly adjacent to Interstate 880 and is within a corridor of known poor air quality (EDF 2020, 2023). Truck traffic is banned on Interstate 580, which runs parallel to Interstate 880 but more inland near the Oakland hills. Interstate 880 carries the greatest volume of truck traffic in the Bay Area region and among any highway in California. The stretch of Interstate 880 near Columbia Gardens sees on average 200,000 vehicle trips per day.
Figure 12. Columbian Gardens Green Infrastructure Plan
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Table 5. Columbian Gardens Green Infrastructure Construction Costs Item Number Cost Unit Construction Cost
Bioretention Areas 60 $17,900 -- $1,074,000
Tree Plantings 104 $1,000 each $380000
Subtotal $581,600
40% Soft Costs $1,674,600
Total Construction Costs $2,035,600
Maintenance (15%, 35
years)
$305,340
Figure 13. Columbian Garden Bioretention Planters Example
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5.2.3 San Leandro Creek Tidal Flooding
Columbian Gardens could also benefit from flood risk reduction structures along San Leandro Creek where floodwaters can overtop the shoreline, as shown on the FEMA SFHA ( Figure 5). This structure would be located along the shoreline on privately owned industrial properties. However, the landowner may not cooperate with the City of Oakland; therefore, these costs are not included in the BRIC grant application.
The preferred solution would be to acquire the properties adjacent to the shoreline and use the properties to expand the San Leandro Creek floodplain and provide amenities and open space for the Columbia Gardens and surrounding communities. However, the cost of this acquisition may be cost prohibitive.
Table 6. San Leandro Creek Construction Costs
Item Length
(feet)
Cost Unit Construction Cost
Sheet Pile Floodwall 1,000 $1,500 LF $1,500,000
Subtotal $1,500,000
40% Soft Costs $600,000
Total Construction Costs $3,600,000
Maintenance (15%, 35
years)
$540,000
5.3 Additional Bay Farm Island Flood Risk Reduction
5.3.1 Lagoon Stormwater Flood Risk Mitigation
Raising the low point along the shoreline at the lagoon tide gate and outfall will prevent coastal floodwater from overtopping the shoreline and causing inland coastal flooding (Section 3.1and 5.1).
However, additional improvements of the lagoon operations are required to remove the inland properties along the lagoon shoreline from the FEMA SFHA. Improvements include installing a pump station at the lagoon outfall to facilitate drawing down the lagoon at all stages of the tidal cycle, improving the tide gate structure, and installing emergency back -up power and controls for automatic operation during extreme events.
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Table 7. Lagoon Stormwater Construction Costs
Item Length
(feet)
Cost Unit Construction Cost
Pump Station -- $2,520,000 unit $2,520,000
Tide Gate and Trash Rack -- $364,000 unit $364,000
Retaining Wall 50 $3,400 LF $170,000
Emergency Power and
Controls
-- $240,000 unit $240,000
Subtotal $3,294,000
40% Soft Costs $1,317,600
Total Construction Costs $4,611,600
Maintenance (15%, 35
years)
$691,740
5.3.2 Northern Bay Farm Island Shoreline Improvements
The shoreline improvements along the eroding areas of the northern Bay Farm Island shoreline are included within the construction costs for the Lagoon shoreline improvements (Section 5.1.2).
Economies of scale can be achieved by completing this stretch of shoreline improvements at the same time, and addressing the shoreline erosion will increase the overall resilience of the Bay Farm Island mitigation actions.
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5.4 Wetland Enhancement for Flood Risk Reduction
In addition to the 0.5 acres of wetland enhancement and expansion at Veterans Court (Section 5.1.3 and Figure 10), additional wetland enhancement to maintain flood risk reduction. The Port of Oakland conducts routing dredging to maintain the channel and turning basin adjacent to the Port of Oakland outside of the project area but within the Oakland Alameda sub -region. This sediment has been beneficially reused to support wetland restoration along the San Francisco Bay shoreline, most notably to support the conversion of the Hamilton Air Field in Marin County to the Hamilton wetlands was used about 7 million cubic yards of beneficially reused dredge material (Photo 7). Thin-layer sediment placement is a recognized strategy to enhance tidal marsh resilience to sea level rise (Raposa et al. 2020; Mohan et al. 2021).
USACE is completing an Integrated Feasibility Study and Environmental Assessment for widening the turning basins, which will produce additional dredged sediment for potential beneficial reuse (USACE 2023). San Francisco Bay Area has lost 85% of its tidal marsh to development and filling of former marshes and Baylands over the past 150 years, and protecting and enhancing these vital ecosystems is vitally important for long-term resilience in the Bay Area (CSCCC and OPC 2010; Goals Project 2015; SFEI & SPUR 2019; SFEI 2021). Save the Bay, a non-profit foundation, has a goal of restoring 100,000 acres of tidal marsh in the Bay.
Photo Credit: USACE
Photo 7. Hamilton Airfield Wetland Restoration, Novato, California
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Martin Luther King, Jr. Regional Shoreline Park and San Leandro Bay provide vital tidal marsh and open water habitat to thousands of birds. Until 1938, San Leandro Bay and its 1,800 acres of tidal marsh were a wildlife paradise, protected as a state wildlife reserve. However, the construction of the Oakland Coliseum Complex, Interstate 880, and the Airport left only 76 acres of tidal marsh remaining by 1986.
The Port of Oakland deeded the remaining wetlands, as well as additional 72 acres of restored wetlands, to EBRPD to complete the Martin Luther King, Jr. Regional S horeline Park. The park offers magnificent views of the wetlands as well as hiking and biking trials. The park is visited by about 300,000 people per year, including the nearby underserved communities.
Arrowhead Marsh dissipates wave energy when the wind fetch is aligned with the San Leandro Airport Channel, and the entire marsh complex also improves water quality in this highly industrialized area.
Fringing wetlands can enhance the lifespan of shoreline flood protection infrastructure while providing a host of other beneficial amenities (Bridges et al. 2021). Augmenting the marsh elevations with the beneficial reuse of sediment would protect shorelines, inland infrastructure, and communities from future sea level rise driven flooding. Increasing the marsh elevations would also preserve tidal mars h habitat under threat from sea level rise, supporting critical habitat for the endangered Ridgway rail and salt marsh harvest mouse.
EBRPD, with local partners, recently repurposed the right-of-way along a portion of Doolittle Drive and created a 2,300-foot multi-model paved and protected trail. To offset the impacts of this project, EBRPD restored one acre of new salt marsh habitat at New Marsh. The construction associated with the flood risk reduction projects proposed by this Oakland Alameda Multi -Hazard Adaptation and Community Benefits Project will require more significant offsets. However, San Leandro Bay offers ample opportunities to offset the impacts within the project area, while also enhancing the flood risk benefits of the projects.
Figure 14 identified wetland areas where thin sediment placement can provide habitat as well as flood reduction benefits. Table 8 provides approximate cost estimates for placing a thin layer (3 to 5 inches) of sediment on top of the existing marsh surface. The estimates include all costs associated with sediment placement, but not include the cost of dredging or tr ansport of the material from the dredge location. Transport of the material to the project area could result in a significant cost savings due to the proximity of the Port of Oakland navigation channel. USACE currently dredges the Port of Oakland navigation channel to maintain water depths for container ships. This sediment has been beneficially for wetland restoration, upland placement, deposited in inland landfills, deposited in San Francisco Bay, or deposited outside of San Francisco Bay at a deep ocean disposal site. The Long-Term Management Strategy for the placement of dredged material in the San Francisco Bay has a goal of at least 40% of dredged sediment being beneficially reused (DMMO 2022).
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Figure 14. Wetland Enhancement and Flood Risk Reduction Locations
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Table 8. San Leandro Bay Wetland Area and Thin Sediment Placement Cost Estimate Wetland Area Acreage1 CY
Sediment
Cost/CY Sediment Place Cost
Arrowhead Marsh 45 18,000 – 30,050 $20 $363,000 – $605,000 New Marsh 35 14,000 – 23,500 $20 $282,000 – $470,000
North Fringing Marsh 5 2,000 – 3,500 $20 $40,000 – $67,000 South Fringing Marsh 4 16,00 – 2,700 $20 $32,000 – $54,000 Model Marsh2 16
Subtotal $718,000 – $1,200,000
40% Soft Costs $287,000 – $478,000
Total Cost $1,000,000 – $1,700,000
1 Wetland acreage was estimated using ArcGIS and may not reflect EBRPD reported acreage. 2 Model Marsh includes the creation of a new marsh in an enclosed area of open water. The cost of creating this marsh is not comparable with thin layer sediment and may be more comparable with the cost of restoring New Marsh.
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6 Literature Cited
AECOM (2014) Bay Farm Island Focus Area. Prepared by AECOM for the San Francisco Bay Conservation and Development Commission and the Alameda County Flood Control and Water Conservation District
Bridges TS, King J, Simm J, et al (2021) International Guidelines on Natural and Nature-Based Features for Flood Risk Management. Engineer Research and Development Center (U.S.) City of Oakland (2022) City of Oakland Drainage Study: Empire Road and Berhardt Drive Drainage Areas. Prepared by Wood Rogers for the City of Oakland
CSCCC, OPC (2010) San Francisco Bay subtidal habitat goals report: conservation planning for the submerged areas of the bay. California State Coastal Conservancy and Ocean Protection Council 147–161
DHI (2011) Regional Coastal Hazard Modeling Study for North and Central San Francisco Bay.
Prepared for the Federal Emergency Management Agency Region IX in support of the San Francisco Bay Area Coastal Study
DMMO (2022) 2021 Dredged Material Management Office Annual Report: Dredging and Placement of Dredged Material in San Francisco Bay: January - December 2021 Report. Prepared by the Dredged Material Management Office
EDF (2020) A Tale of Two Freeways. Prepared by the Environmental Defense Fund EDF (2023) Air pollution and health in East Oakland. Prepared by the Environmental Defense Fund FEMA (2023a) Community Disaster Resilience Zones
FEMA (2023b) National Risk Index: Technical Documentation. Federal Emergency Management Agency
FEMA (2018) Alameda County Flood Insurance Study. Federal Emergency Management Agency FEMA (2023c) National Flood Hazard Layer Viewer
FEMA (2023d) Engineering with Nature: Alternative Techniques to Riprap Bank Stabilization. In:
Federal Emergency Management Agency.
https://www.fema.gov/pdf/about/regions/regionx/Engineering_With_Nature_Web.pdf Foster City (2016) Foster City Levee Protection Planning and Improvements Project: Draft Environmental Impact Report. Capital Improvement Project No. 301 -657, State Clearinghouse No. 2016012012
Foster City (2020a) Foster City Levee Improvements Project Bid Tabulation Spreadsheet Foster City (2020b) Foster City Levee Improvements Project Final Plans
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Goals Project (2015) The Baylands and Climate Change: What Can We Do. Baylands Ecosystem Habitat Goals Science Update 2015. prepared by the San Francisco Bay Area Wetlands Ecosystem Goals Project. California State Coastal Conservancy, Oakland, CA Holmes R, Burkholder S, Holzman J, et al (2022) Integrating Engineering With Nature® strategies and landscape architecture techniques into the Sabine‐ to‐ G a lveston Coa sta l Storm R isk Management Project. Integr Envir Assess & Manag 18:63– 73. https://doi.org/10.1002/ieam.4434
Krasna R, Rella A (2023) Nature-inclusive shoreline protection installed in San Diego. ASCE From the Field
May CL, Mak M, Harris E, et al (2016a) Extreme Storms in San Francisco Bay – Past to Present.
Federal Emergency Management Agency
May CL, Mak, M, Harris, E, et al (2016b) San Francisco Bay Tidal Datums and Extreme Tides Study.
Prepared by AECOM for the Federal Emergency Management Agency Region IX and the San Francisco Bay Conservation and Development Commission
Mohan R, Piercy C, Welp T (2021) Thin layer placement for marsh enhancement: Planning, design, construction, and monitoring considerations. Shore & Beach 4– 12. https://doi.org/10.34237/1008941
Port of Oakland (2021) The Economic Impact of the Port of Oakland. Prepared by Martin Associates for the Port of Oakland
Port of Oakland (2023) Stormwater Management and Tidal Flooding Vulnerability Assessment at North Field Oakland International Airport: Tidal Flooding Vulnerability Assessment. Prepared by Wood Rogers for the Port of Oakland
Raposa K, Wasson K, Nelson J, et al (2020) Guidance for thin-layer sediment placement is a recognized strategy to enhance tidal marsh resilience to sea level rise. Publishd in collaboration with the National Estuarine Research reserve System Science Collaboratives SFEI (2021) Ecotone Levees and Wildlife Connectivity: A Technical Update to the Adaptation Atlas.
Publication #1037
SFEI & SPUR (2019) San Francisco Bay Shoreline Adaptation Atlas: Working with Nature to Plan for Sea Level Rise - Using Operational Landscape Units
USACE (2024) Appendix J. Engineering with Nature
USACE (2 023) Oakland Habor Turbing Basins Widening: Draft Integrated Feasibility Report and Environmental Assessment. Prepared by the US Army Corps of Engineers