The unincorporated coastal community of Marin City is located just north of Sausalito in Marin County. It sits in a bowl, surrounded by forested hills, with Highway 101 running along its coastal edge. Much of its developed land is just 5-10 feet above sea level. Marin City was founded during WWII as workers moved to the area to build wartime ships. After the war, the community became largely African American, as redlining and housing discrimination prevented residents of color from relocating to other areas of Marin. Marin City now boasts a health clinic, middle school, and strong community bonds but has continued to fight issues of environmental and social justice. The city was once a Superfund-era dumping site. There are community concerns of displacement due to a regional housing shortage and the city is a food desert, without a single grocery store. And, the community is vulnerable to flooding as a result of climate change and failing infrastructure.
The goal of this studio was to propose a pair of landform interventions (such as berms, trenches, plateaus, or terracing) to tackle the issues of sea level rise, groundwater immersion, and stormwater runoff from the hills of Marin City. Because the majority of the city lies at a low elevation, it would see early groundwater immersion from rising sea levels long before experiencing flooding from sea level rise. The first area affected would be the Highway 101 off-ramp into Marin City as well as the shopping center and drainage pond just inland of the highway. Existing evidence of subsidence and flooding suggested physical design interventions were needed to preserve Marin City’s quality of life.
My team and I decided to embrace the idea of “living with the water” – enabling natural systems to function properly and harness those systems to protect community life. Shorter- and intermediate-term strategies included opening up the drainage pond area to more permanently connect to the shore and ocean, enabling marsh restoration under Highway 101. We planned for more cut of sediment at the shopping center site, transitioning this space to marshland that could function as a buffer. A third area of cut, to occur at a later phase, was proposed on the east side of the town (adjacent to Highway 101), which would see early flooding. This cut could accommodate excess storm and sea water as a detention pond. Additional detention ponds and forebays were planned in the foothills of Marin City to slow and capture excess rainwater in major storm events.
Teams were also asked to propose long-term strategies for 6′ of sea level rise, estimated to occur 70 years from present day. At this stage, much of Marin City’s “bowl” would see flooding. These long-term strategies could guide future planning and development of Marin City, as existing infrastructure and buildings reached their end of life. The core concept of our plan proposed a series of canals (trenches) to collect and discharge rain from the hills and excess stormwater. Tide gates on the canals would protect the town from storm surges. Cut from the canals would be used to slowly raise the ground elevation of much of Marin City over generations.
Phase 1 (1′ SLR)
Raising the ground level of Marin City would require careful planning and phasing to preserve existing housing and add infill housing while preventing displacement of residents. Central community services, including the middle school, senior center, and health center, are at a high enough elevation to not flood. Thus, this valued core would be preserved as a critical resiliency asset for the community. Our team’s scheme anticipated growth of Bay Area housing pressures, and depicted a building layout designed to accommodate an additional 3,600 housing units. Replacement development included residential mixed-use, non-profit and manufacturing space, senior housing, and retail and commercial for groceries and shops.
Illustration of a bike/ped path in Marin City
A linear shoreline park was proposed along the edge of the restored wetland, with viewing areas and a bike path. A central boulevard connected through the spine of the town out to Sausalito and would accommodate a new public transit route. Swales would be integrated along the town’s streets to wick away stormwater into the canals.
My team further studied the flow of water by developing a series of section diagrams through various locations of the town to understand how our interventions would work. Each member prepared several sections; mine covered the upland forebays connecting across Drake Boulevard to the start of the canals, shown below.
Section through foothills showing potential forebays
Section through Drake showing stormwater connection and terracing
Additionally, I looked at ways of reusing rainwater (greywater) within new and existing development (shown below). I proposed siting constructed wetlands between building development to filter rainwater for irrigation or other process water uses. These constructed wetlands could also accommodate cisterns to collect rainwater to be used in toilets and dishwashers. These measures would enable Marin City to become incredibly water resilient.
Constructed wetlands and greywater proposal
