San Anselmo Flood Risk Reduction Project

by Sandy Guldman
The San Anselmo Flood Risk Reduction (SAFRR) Project comprises three components: (1) Sunnyside Nursery Flood Diversion and Storage Basin at 3000 Sir Francis Drake Blvd; (2) the removal of the building at 634 San Anselmo Avenue and creek bank stabilization at the site; and (3) flood mitigation measures on downstream private properties that may see impacts from the project.
1. Sunnyside Nursery Flood Diversion and Storage Basin (FDS)
A design team has conducted additional studies needed to support final design of the diversion structure, overflow weir, and refined grading plans for the basin and the embankment. The team has also drafted sediment management, woody debris management and operations plans, and conducted a structural evaluation of the existing access bridge to the FDS. The 60% design plans are currently in the review process and are expected to be completed by the time this newsletter is published.
2. 630–636 San Anselmo Avenue
L’Appart restaurant has vacated the property. The other businesses are still in operation, but they are expected to complete relocation activities by the end of January 2020. The Flood Control District is currently assessing the existing buildings for demolition techniques and expects to remove the buildings in early 2020. The concrete slab foundation that spans the creek will remain in place until final permit approval and the main construction contract is awarded which is expected in 2021. The design team has continued the geotechnical investigation of the site to refine project design. The District is working closely with the

High water in San Anselmo’s Creek Park in 2005. Concrete decking on the right— including l’Apart restaurant—will be removed in 2020–2021. Photo by Charles Kennard

Town of San Anselmo to incorporate certain elements of the Reimagine Creek Park vision into the SAFRR Project. The updated design includes leaving the right bank retaining wall in place to maximize room for a new pedestrian plaza along San Anselmo Avenue as part of the Reimagine Park concept design. The approved Project EIR includes a new pedestrian plaza, replacing the existing performance stage, and new pedestrian bridge abutments. The 60% design plans are expected in early 2020. Collaboration on the Reimagine Creek Park elements resulted in about a four-month delay to the Project design. This delay will move construction of the Project until 2021.
3. Private Property Structure Flood Risk Mitigation
The design team has developed a hydraulic design of the upstream elements of the project and assessed the impacts to structures adjacent to San Anselmo Creek downstream of 630–636 San Anselmo Avenue. Where there may be impacts to homes that would require mitigation, the District is planning to work with these individual homeowners to determine suitable measures.