500 Series - Flood Damage Reduction
Section 500- The Repetitive Loss List(0 pts)
Despite the severity of San Anselmo's flooding problem, the Town has only one repetitive loss property and no severe repetitive loss properties. This property is in the vicinity of Sleepy Hollow Creek and Fire Station #20, presumably affected by flow constriction at the culvert under Arroyo Avenue. San Anselmo has begun annual outreach to the property owners.
Activity 510 – Floodplain Management Planning(622 pts)
• 512 (a) (382 pts)
San Anselmo has a FEMA-approved Local Hazard Mitigation Plan and is currently in the process of doing an update. The existing plan is a multi-jurisdictional multi-hazard plan created by the Association of Bay Area Governments (ABAG) in 2010 and annexed by the Town in 2012.
Attachments: FMP Checklist
LHMP with callouts referring to FMP Checklist
Resolution adopting 2010 plan
The Town is currently in the process of updating its Hazard Mitigation Plan and anticipates submitting it to FEMA for approval before the end of 2015. This update will not be an annex, thus we are following the FEMA & CRS guidance in order to recieve maximum credit.
Link: LHMP update webpage
• 512 (c) Natural Floodplain Functions Plan
San Anselmo’s floodplain is so completely developed that there are limited opportunities for restoring the floodplain’s natural functions in a wild way. The Town General Plan has a Land Use Element with the stated goals of reducing flood damage and protecting the natural state and function of creeks. It states that creeks should be kept in their natural state or restored, and bolsters the municipal code sections that require a 15-foot setback from creeks.
Link: San Anselmo General Plan
Activity 520 – Acquisition and Relocation(2250 pts)
522 (a) In 2013 a 6,500 square foot commercial building in the Town’s regulatory floodway was removed and turned into a park. The Rossi Pharmacy building, at 535 San Anselmo Avenue, directly next to Town Hall, is now Imagination Park. It was donated to a non-profit the San Anselmo Community Foundation by a philanthropic resident and contains grass, benches, a fountain, and bronze statues of Yoda and Indiana Jones. During the Planning Commission Meeting on the subject, on January 7, 2013, the Public Works Director affirmed that it was in the regulatory floodway and its removal would have a beneficial effect towards reducing floodwater elevations.
535 San Anselmo Avenue Documentation:
• Map of Imagination Park
• Elevation Certificate
• Interoffice Memo
• Planning Commission Staff Report and Minutes 1/7/13
• CA Park and Recreation record
Building Bridge 2 grant application materials to FEMA Hazard Mitigation Assistance program (is any credit available for the $100k spent on Building Bridge 2 Acquisition and Relocation grant application material?)
Activity 530 – Flood Protection
532 (a) San Anselmo implements a combination of Flood Protection technique.
These are primarily in place through the Building Department.
TUE. Residential buildings are more commonly elevated above the BFE. In San Anselmo, 18 buildings have been raised.
Attachment: list of preFIRM residential buildings that have been raised
TUD. The Town Building Department requires, and provides assistance with, installation of removable flood gates at the doorway to each commercial building in the floodplain. The Building Department provides guidance (see section 352c) designed by the Building Official, a registered engineer, however the individual gates are installed by contractors and are unique to each building.
There are well over 100 of these flood gates installed, protecting 60+ buildings and about 95 individual stores.
Link:Town guidance for flood gate installation
Three Town-owned buildings are engineered and certified floodproof with removable gates. Two of these buildings, Fire Station 19 and the Town Offices, are critical facilities.
Attachment: Town Hall Floodproofing Construction and Engineering certifications
‘Wet Floodproofed’ buildings (TUW)- No credit requested
Sewer backup prevention (TUS)- Sanitary sewers are managed by the Ross Valley Sanitary District. All new and substantially improved buildings in San Anselmo are required to test their sanitary sewer lateral and install backflow prevention of some sort, however comprehensive records of these are not available. RVSD staff estimates 35% of existing houses have sanitary sewer backflow prevention.
562 SFHA houses x .35 x .2 = 39 points
5568 non-SFHA houses x .35 x.1 = 195 points
Barriers levees floodwalls- No credit requested
532 (b) Flood Protection improvements such as barriers around individual buildings
532 (c) Protected Buildings (looks like multipliers for TU_ credits from 532a?)
Activity 540 – Drainage System Maintenance(570 pts)
San Anselmo Public Works Department has an active program for inspecting and maintaining the channel free from obstructions. This program is conducted in coordination with Marin County Flood Control District’s guidelines and regulatory permits, called the Routine Maintenance Agreement, or RMA.
Every year, during the dry season, someone from SADPW walks the entire mainstem of San Anselmo and Sleepy Hollow Creek within the incorporated Town limits. Along the way this person takes pictures and notes obstructions or potential maintenance needs. According to the RMA, this person has training in identification of such hazards and Best Management Practices for finding an appropriate balance between flood control removals and a healthy stream ecology.
The area covered by the program, as stated, includes the entire length of San Anselmo and Sleepy Hollow Creeks. Sorich Creek and smaller tributaries are also included in the Town’s maintenance programs, but are too small to walk the entire creek every year.
Inspection procedures for this annual maintenance include taking pictures of identified obstructions or problems and compiling a list or map known as a “Work Plan”. At a meeting with the Marin County Flood Control District and other Towns, each Town discusses its Work Plan and maintenance needs for the year, after which the available pot of funding is divided accordingly.
Maintenance procedures are then implemented by the Town DPW using a combination of abatements (on private property), Town staff, or another contractor such as the North Bay Conservation Corps. Pictures of the work are taken again afterwards for reporting to the permit agencies.
Known problem sites do exist and are monitored more closely during the winter months and after storms. These sites are primarily bridges which catch debris: Lansdale, Saunders, Nokomis, Madrone, and the Building Bridges downtown.
Additionally, the Town staff responds to emergency and non-emergency calls to help remove obstructions all year long.
Another form of drainage system maintenance that the Town DPW performs is annual inspection and cleaning of its underground stromdrains such as catch basins and pipes. In certain places these structures fill will gravel and cobbles, which necessitates annual removal with a vactor truck. This is being documented for compliance with section E.11 of the California State Water Quality Control Board Phase II Permit
542 (a) Channel Debris Removal (200 pts)
San Anselmo removes debris from the channel, and assists residents and other municipalities in doing so. We are proactive about removing larger concrete obstructions (see attachment example from Sleepy Hollow Creek at Drake High School). We also remove garbage, when illegal dumping has occurred.
We write letters of abatement requiring people to remove debris, when the person responsible is known.
The most problematic debris, from a flood control perspective, is vegetation. We have an active vegetation maintenance program, but logs get stuck at bridge crossings pretty frequently, particularly at the fish ladders. Thus these are our known problem sites.
Attachment: Maps of known problem sites & stream reach names
Creek Routine Maintenance Program & Appendices
Work Maps from 2014
Another major debris problem is concrete debris. In the past, broken concrete was often used to reinforce banks. San Anselmo recently removed several cubic yards of concrete debris from the bed Sleepy Hollow Creek.
Attachment: Permits for debris removal from CA Department of Fish and Wildlife and the Regional Water Quality Control Board
542 (b) Problem Site Maintenance (50 pts)
Annual creek maintenance is based upon summer inspections, and work, which is focused at known problem sites, happens in the fall. In 2013 the Town hired the Conservation Corps to clear vegetation upstream of Saunders Bridge. In 2014 we focused vegetation clearing on the downtown reach of San Anselmo Creek. Any of our bridges or buildings which are not free-spanning the creek are considered potential problem sites.
In addition to annual maintenance, these sites are watched by residents and DPW staff during high-flow events. The 1950’s style metal fish ladder under Saunders Avenue collects logs almost every storm.
See attachment under 542a for map of problem sites.
542 (c) Capital Improvement Program (CIP) (70 pts)
San Anselmo is part of a Flood Control District operated by Marin County Department of Public Works. The Flood Control District has a CIP, which identifies flood mitigation projects throughout the watershed which, if completed, will cumulatively keep the 100-year flood inside the creek channel. Residents of San Anselmo pay ~$180 per year into the program, and the remaining costs are grant funded.
The CIP, and its 10-year work plan can be found on the Flood Control District webpage
Link to Flood Control District Webpage
San Anselmo has a 7-year Capital Improvement Plan for itself which includes streets, buildings, parks as well as drainage and flood control. This CIP is available on the Town website.
Link Town Council Agenda approving 7-year CIP (see item 7)
Listed in these two CIP reports are plans for removal and replacement of several bridges in Town. San Anselmo received funding from Caltrans to replace three of these bridge, all of which are known constrictions. Where should this go to recieve CRS credit?
542 (d) Stream Dumping Regulations (30 pts)
San Anselmo has regulations against dumping of any debris into our watercourses, which are actively promoted and enforced.
Link: Muni Code Title 7, Chapter 12