This “hold the line” concept sketch shows an armored sea wall along the existing shore reach from the Richmond-San Rafael Bridge to city land on the edge of an elevated rocky promontory north of the Canal at Bay Way. The sea wall is a traditional engineered levee of sufficient height to reduce flood risk and address sea level rise within a design time horizon.
- A movable storm “gate” and pump facility are located at the mouth of the Canal. This would provide protection from storms and rising seas for properties behind the sea wall and gate including those along the Canal estuary.
- The sea wall would be located on the existing berm, except where it crosses the Canal. The sea wall would be exposed to full wave action and storm surge.
- The canal would be open to tidal action except at unusual tidal and storm events; a tidal gate would provide protection for upland areas when required.
- Pump stations remove storm runoff from protected areas.
- An armored sea wall is considered a traditional “grey” infrastructure solution. It holds little promise for creation of shore habitat and must be of sufficient height and robust construction to resist full exposure to storm surge and wind-driven waves (fetch).
- Wetland mitigation could occur on or off site.
As with the previous “hold the line” concept, a berm would be constructed along the existing shore reach from the Richmond San Rafael Bridge to the city-owned land at Bay Way. Unlike a traditional armored sea wall, the concept relies on a horizontal levee ecotone habitat to buffer the energy of storm surge and fetch, augmented with pump stations removing storm runoff from protected areas and using the tide gate to protect the canal during unusual tidal and storm events.
- The ecotone could replace much of the marshland filled when the San Rafael valley was developed from the 1800s to the 1980s. This would require placement of fill material on shallow bay waters and mud flat fringes adjacent to the existing shore. It could provide a more continuous, natural habitat between Point San Pedro and the Corte Madera marsh.
- A movable storm gate would be placed at the mouth of the Canal to protect upland areas. Fill material from maritime dredging could be used to create the ecotone, however, it would need to be added to over time to compensate for rising seas. Armoring with cobble, beaches, breakwaters, or groins would likely be required where the ecotone meets the open bay water. The design of the ecotone and bay edge would require scientific study and beta testing of different prototypes.
- Fill of shallow bay waters is typically not permitted. Resource agencies including the Bay Conservation Development Commission and the Region Water Quality Control Board are exploring modifications to their fill regulations to allow horizontal levees in response to sea level rise.
The Figure 3 concept section sketches relate to the previous exhibits Figure 1 and Figure 2.
- Section A shows armored sea wall along the existing shore, which must be robustly built to resist the erosive force of deep storm surge and fetch.Stone armor has limited habitat value. The armored sea wall could be raised incrementally with investments made based on risk reduction and observed changes in the sea level.
- Section B shows a berm/ecotone. The berm is shown along the existing shore. The ecotone is placed bayward of the berm. It would be established on maritime dredge material deposited in shallow subtidal waters. The erosive force of storm surge and fetch would be dampened by raising the bay elevation sufficiently to support salt marsh and other habitat.
The friction caused by marsh vegetation, combined with reduced water depth, dissipates wave energy in storms. The berm/ecotone would not need to be as high as an armored sea wall, but would still need to be raised over time to compensate for rising seas. Design of a manageable interface would be required to separate recreational uses from protected natural habitat. The edge facing the open bay would also need to be designed to resist erosion.
This diagram focuses on rail and ferries, while proposing a main line multiple use path system (including a bicycle highway) for the North-South Greenway/Great Redwood Trail to the North Bay, Wine Country, and the Redwood Empire. The diagram also proposes the following:
- A recognition of the San Quentin complex as an essential public resource that merits improvement. San Quentin Prison, the flagship prison of the California Department of Corrections, has more volunteer support than the rest of the California prison system (combined), including pro bono legal services.
- A new ferry terminal at San Quentin on a larger site, allowing for increased capacity (more berths, larger turning basin, more train storage) and access to multiple destinations.
- A seamless connection between SMART rail and the proposed San Quentin ferry terminal, reducing transfer time (by an average of 20 minutes/roundtrip).
- Developing and prioritizing parallel capacity in transportation networks; reconfiguring transportation networks to provide greater resiliency, expanded user options, and significantly reduced cross-bay water transit times (by an average of 15 minutes/roundtrip).
This concept sketch considers the roles of San Rafael and San Quentin as transportation gateways to points north. It addresses local and regional needs vis-à-vis roadway and transit deficiencies resulting in mobility, economic, and social justice impediments. The sketch proposes the following:
- Relocate SMART and Ferry terminals from Larkspur to Point San Quentin, enabling direct cross-platform transfer, reduced water transit time, more space for ferry berths and future expansion, and a transportation hub and village for prison staff, visitors, and services.
- Construct a new East San Rafael Interchange connecting from Andersen to Kerner, providing improved access and egress for the disadvantaged Canal neighborhood, Southeast San Rafael and San Quentin; provide access to a new San Quentin ferry terminal; relocate problematic ramp movements away from the Bellam interchange.
- Complete the US 101/I-580 Interchange including dedicated ramps from Westbound I-580 to Southbound US 101 and from Northbound US 101 to Eastbound I-580. These ramps would reduce rush-hour queueing and take regional trips off local streets.
- Construct I-580 corridor improvements between the Richmond-San Rafael Bridge and US 101 by eliminating an unsafe hook ramp and adding auxiliary lanes.
- Construct a new Bellam SMART Station to serve Canal neighborhood and Southeast San Rafael employers and provide bus transit linkage connecting central and southern Marin.
The existing ramps at US 101, I-580 and Bellam function poorly due to the proximity of the Bellam Interchange to the US 101/ I-580 interchange and East Francisco Boulevard. There are too many movements (including difficult turns) in a very confined and conflicted series of intersections and interchanges, resulting in inadequate stacking and a short weave. Although the new ramps are aimed at decreasing congestion, the wrong outcome could severely limit access to Southeast San Rafael for generations.
We have identified alternative concepts for consideration in the design and environmental review process including:
- Relocate Bellam ramps to a new East San Rafael interchange. Moving access ramps to a different location (approximately half-way between the US 101/I-580 interchange and the Main Street San Quentin Village interchange) would improve mobility, eliminate back up onto the freeways, and reduce conflicts and increasing pedestrian and bicycle safety.
- Upgrade Bellam to a Complete Street. Bellam Boulevard has emerged as the main street for East San Rafael and the Canal Neighborhood with significant vehicular, pedestrian and bicycle traffic, essential business services, and social infrastructure. Simplifying vehicular movement around the I-580 interchange would support evolution of Bellam into a complete street, including protected bicycle lanes, sidewalks and pedestrian refuges.
- Close the hook ramp from East Francisco to I-580 because the existing hook ramp is an unsafe and extremely tight radius ramp that conflicts with the Sir Francis Drake off-ramp. This results in an extremely short weave between vehicles accelerating onto the freeway and those decelerating to exit at Sir Francis Drake Boulevard.
- Optimize non-limited access facilities for pedestrians and bikes. Roadway, bridge and intersection design should include protected bike lanes, sidewalks separated from the traveled way by parkway panels with street trees and pedestrian refuges in medians. All new streets and intersections (excluding limited access ways such as freeways) should be designed to safely and graciously increase mobility options and reduce emissions.