San Francisco: Green Benefit District (GBD)

Coastal Flooding

Many of San Francisco’s waterfront communities, such as Dogpatch, are vulnerable to the impacts of sea level rise. Dogpatch already experiences flooding and sewage back-up due to the compounding effects of heavy storms and king tides as seasonal sea level rise. The GBD will encounter more severe and sustained flooding and sewage backup as permanent sea level rise fully takes hold. This is a sought-after location due to 1) the district’s combination of traditional Victorians and industrial buildings; 2) zoning changes that allow for the addition of as many as 5,000 more housing units by 2025; 3) more direct access to Silicon Valley and other business cores south of the City; and 4) increasing density and development in other parts of the City which have pushed development to Dogpatch. Living with water becomes an imperative as more population moves towards waterfront locations most vulnerable to the impacts of climate change and sea level rise.

According to the Coastal Processes Study, the FEMA flood prediction for the 100-year storm event today and in the future suggest that all major capital improvements should be located or raised above 20’ (NAVD 88) while soft-edge strategies should be employed for shoreline protection and wave energy dissipation. At the eastern edge of the booming Dogpatch neighborhood is the 28-acre Pier 70 development at five to 10 feet above sea level. Based on data from the SFPUC, a large portion of the development will be within the 100-year floodplain by the end of the 21st century when the storm surges could reach 6.4 feet. The developer, Forest City, plans to retreat 100 feet from the current shoreline, to raise waterfront edges to the 2100 sea-level-rise projection to protect the development from rising tides. The most recent environmental impact assessment report for Pier 70 suggests that this will be in the form of an engineering berm about four feet in height.

Climate adaptation measures implemented along the shoreline of waterfront developments and open spaces to the north, east, and south may alleviate or worsen climate-induced flooding in Dogpatch. Conversely, upstream climate adaptation strategies in Potrero Hill will influence Dogpatch’s climate adaptation capacity, which in turn will affect the extent of bathtub effects resulted from various shoreline climate adaptation scenarios to influence the flood vulnerability of both Dogpatch and all adjacent waterfront properties.

River and Inland Flooding

Dogpatch is nestled within a Peninsula bordered to the north and south by the Mission Creek Outfall and the Islais Creek Outfall. As a consequence, the neighborhood is vulnerable to extreme flooding from these tributaries, particularly when their peak discharges coincide with high tides.  The Peninsula was created from the Mission Bay with landfill, which is subject to liquefaction during earthquakes. Parts of Dogpatch between the 20th and the 22nd Streets sit on impermeable serpentine soils, making the neighborhood prone to drainage issues. Dogpatch is located just outside of the Channel Basin, Waste Water Collection System (Figure 1). A pump station is located at the intersection of Tennessee and Tubbs. The existing combined sewage system is not sufficient for the increasingly more intense climate-induced storms because they are designed to handle 3 hours of 5-year storm. Tennessee and Minnesota are prone to flooding due to blockage in the sewage system. Flooding has been observed in various upland locations, including the corner of 17th and Hampshire and the intersections of 16th and Potrero. A possible cause could be a localized high spot on Division between Harrison and Bryant. The high spot requires the storm drains to go around as it continues north of Division and loops around to 11th and back to Division. The acquisition of Byer warehouse building at Division and Treat have been thought to be a possible solution to allow storm drains to go through. The manhole covers have been seen lift off from the street and carried away an inch or two at the intersection of 18th and Potrero possibly due to a blocked drain. Underground streams have been suspected to result in a similar situation on 18th between Utah and Potrero. Flooding has been found around the street drain at the corner of Vermont and 17th. The bottom floor of a house at 575 San Bruno Ave. was flooded and had to be replaced. To mitigate the potential increase in runoff from the Pier 70 development, a pump was proposed because gravity flow is not possible in certain areas lower than sewage system. The pump takes sewage to the SE treatment plan through a 60” forced main going north south in Dogpatch. The city is planning to implement large gravity-based tunnel for flood resiliency because of the sewage blockage north of Dogpatch. A 20”-30” diameter tunnel is also proposed under the Potrero Hill and will be built in about five years.

Sustained Droughts and Costly Water Supply

San Francisco has experienced year-round droughts for the fourth year. As a consequence, San Francisco residents are experiencing steep price hikes for water. Since 1934, the city has gotten most of its potable water from the Hetch Hetchy reservoir, 160 miles away in the Sierra Nevada Mountains. Historically, there have been many underground creeks and springs as possible decentralized potable water sources. In the 1800s, Russian immigrants had wells with ample springs that allowed them to take steam baths at home. The Albion Castle was built over the fresh springs in Hunters Point just south of Dogpatch by the Albion Ale and Porter Brewery. Tunnels were cut into the hillside to collect water seepage to make beer, and the brewery was built to look like a Norman castle. The San Francisco Mountain Springs Water Company bought the property for the springs. Before the drought, 10,000 gallons of water passed through here each day. Similarly, the ground of the Civic Center BART station holds water like a sponge. Similar tunnels were dug to collect about 40,000 gallons of water each day with pumps running constantly to keep the water at bay. However, these underground water sources have not been fully harnessed to address the portable water crises. Instead, they have unnecessarily burdened water treatment plants and contributed to daily sewage discharges. The San Francisco Public Works is aware of and monitoring the seepage of the underground springs and creeks into the sewage system because of the increasing salinity level detected in treatment plants. Capturing these underground water sources could help reduce the operational cost of water treatment plants and flood risks during climate-related mega storms in areas near sewage discharge points.

Multiple Lines of Defense for Coastal, Riverine, and Inland Flooding

We will study how different climate adaptation scenarios in adjacent waterfront properties affect Dogpatch’s climate adaptation needs and vice versa to optimize the conception of multiple lines of defense for tackling the compounding effects of coastal flooding, riverine flooding, and inland flooding. Specifically, we will use a phasing approach to investigate possible ways to address Dogpatch’s existing and future vulnerability to inland flooding through water-sensitive designs in Tunnel Top Park, Esprit Park, and the various green spaces along alley edges and Highway 280 to the West, including the Loop, which is being designed by Bionics. Part of Minnesota is just east of the Esprit Park. For example, the immediate phase could potentially prioritize the integration of controlled flooding within Esprit Park and the right-of-way of Minnesota Street to attenuate the street’s existing flood vulnerability.

A future phase may be composed of inland flooding interventions as place-making opportunities for mitigating the bathtub effect of various future in-water and shoreline climate adaptation scenarios for various waterfront projects, including the Pier 70 development, waterfront redesign for the Warrior’s Arena, the sustainable development by Build Inc. at the India Basin, and Crane Cove Park redesign. For example, the 100 feet shoreline buffer zone proposed by the Pier 70 developments provides opportunities for creating habitats and amenities that serve as in-water interventions to mitigate the impacts of storm surges and sea level rise. These in-water interventions can be hydrologically connected with the Bay and groundwater as a tidal wetland park or hydrologically insulated as a polder park, which is the basis upon which the Netherlands is able to keep three quarters of its land dry with below-sea-level elevations. These two systems will be evaluated in terms of their aesthetic, infrastructural, social, and environmental performances in addition to their bathtub effects on nearby waterfront properties and particularly Dogpatch. In sum, we will explore inland, shoreline, and in-water interventions and an interconnected system of ESPs as multiple lines of defense to help Dogpatch become more resilient to the impacts of climate change and sea level rise.

Interconnecting Climate-Adaptive Ecosystem-Service Providers (ESPs) into a System of Blue Parkways

The ESPs will be embedded within an aesthetically pleasing system of blue parkways composed of streetscapes, the blue greenways proposed by the city, and open spaces, including Warm Water Cove Park, Crane Cove Park, Esprit Park, and the Loop. In addition to a rising sea level, climate change has led to more sustained droughts and more intensive storms, necessitating green infrastructure to be up-scaled to accommodate more water retention to mitigate both riverine and inland flooding. Specifically, water retention helps facilitate water reuse during droughts and more effective mitigation of climate-induced flooding and combined sewer overflow into the San Francisco Bay and Pacific Ocean during heavy rains. Water retention is also the basis for transitioning the GBD into a climate-adaptive ecodistrict through promoting its self-sufficiency in water, food, and energy. To introduce more water retention with public acceptance in both Dogpatch and Petrero Hill, we will explore ways to synergize previous public realm planning efforts for with climate adaptation thinking as place-making opportunities in the public realm for the GBD. Specifically, we will attempt to integrate up-scaled green infrastructure and public realm amenities to promote place identity, environmental education, diverse community activities, stewardship, and financial sustainability. At the same time, we will investigate how these components may also facilitate multi-modal integration of transit, train, pedestrian, bike, sedan, and other vehicles to for daily safety and emergency evaluation needs in the event of flooding. Mega floods in a drought-prone area like San Francisco could potentially be an opportunity to maximize water capture for use when there is little rainfall. We will investigate ways to maximize water retention through controlled flooding in the public realm and structural solutions for rainwater harvesting because dogpatch’s ground water table is vulnerable to brackish water invasion from the Bay.

Enabling Climate-Adaptive Ecodistrict-Making with a Community-Owned Utility Model

Recent changes in Water Department policy allows for a few percent of San Francisco’s tap water to be from the Westside Basin aquifer, mixed into the rest of the supply. Golden Gate Park and the Presidio (including its tap water) are mostly from groundwater sources now. There are abundant underground creeks and springs just northwest and southwest of Dogpatch as a possible water source to be harnessed for decentralized potable water supply. Local water reuse and water retention are essential for transforming Dogpatch from a GBD into a climate-adaptive ecodistrict that derives its self-sufficiency in water, food, and energy from decentralized water sources. Major upgrades within the right-of-ways present opportunities for realizing this community-owned utility model and creating public amenities. These planned upgrades can be found in the GBD Green Vision Plan. Through harnessing the water-food-energy nexus, we will investigate the potential of a community-owned utility model in helping leverage the GBD’s development pressure for environmental, social, and economic benefits. Specifically, we will investigate design strategies to maximize the model’s revenues to help finance its implementation and future climate adaptation measures in addition to encouraging place attachment and stewardship.

Ecodistrict-Making through Participatory Design

The Alaska Airlines’ Imagine Tomorrow Travel Awards for the Itron Food, Energy, and Water Nexus, the Biofuels Challenge, and the McKinstry Built Environment Challenge will provide mileage for our field trip to San Francisco from January 26 to 29. The Washington State University’s Center for Transformative Learning and Leadership will sponsor design research activities to help us better design the public realm with ecosystem services to induce place attachment and stewardship. We will conduct fieldwork on January 26 and 27 and host community workshops from January 27 to 29 to understand site contexts and stakeholders’ needs. In each workshop, we will first have participants take a survey for 20 minutes. Half of the participants will take the survey with images of climate-adaptive water urbanism prototypes while the other half will take it without the images. Then, we will make a 20 minute presentation to share site and SWOT (Strength-Weakness-Opportunity-Threat) analyses and best practices that informed each climate-adaptive water urbanism prototype as a game card in addition to possible siting strategies for each prototype. Through conducting design games, we will work with stakeholders to collectively generate alternatives for locating and designing these prototypes as an interconnected system of ecosystem-service providers that double as public realm amenities to help meet the following objectives:

1) Enhance quality of life, place identity, and stewardship through climate-adaptive public realm design.

2) Support energy efficiency, renewable power, and decentralized wastewater treatment and reuse;

3) Harness the potential for district-scale wastewater treatment and reuse;

4) Investigate opportunities for strengthening stormwater management, flood resiliency, and emergency preparedness;

5) Mainstream ecosystem service providers for public acceptance through cultural ecosystem services;

6) Redesign public realm to better meet user needs and to promote healthier urban living;

7)  Improve wayfinding and the GBD’s identity and image as a coherent urban district;

8) Maximize the environmental, social, and economic performance of a community-owned utility model.

From Alternatives to Final Scheme

After the field trip, we will interview experts on the pros and cons of each alternative. The alternatives and the expert evaluations will be used to inform an internal design game among ourselves and students from allied disciplines to generate final schemes for siting urban design and site-specific design interventions.