CANCELED – Zone 4 Advisory Board Meeting: July 23, 2024
6:30 pm
FLOOD ZONE 4 ADVISORY BOARD
STATEMENT OF PROPOSED ACTION
JULY 3, 2024
This Statement of Proposed Action has been prepared in lieu of meeting. According to the California Water Code, Section 68-6.2 Marin County Flood Control and Water Conservation District (District) staff submits this Statement of Proposed Action to provide any Zone 4 Advisory Board (AB) member an opportunity to respond or provide written comment on the recommended action items outlined below within the next 30 days on or before August 3, 2024. The next meeting is October 22, 2024.
Any individual AB member may contact the Flood District at floodinquiry@marincounty.org to discuss any items related to the zone. To comply with Brown Act requirements, all meetings of a quorum of AB members to discuss Zone business must be publicly noticed.
Item 1. Review Meeting Minutes: April 16, 2024
Draft minutes can be found here:
https://flooddistrict.marincounty.gov/meetings/zone-4-advisory-board-meeting-april-16-2024/#/tab-minutes
Item 2. Restoration of East and West Creeks
Background: At the October 2022 meeting, civil engineer and geomorphologist Matt Smeltzer of Geomorph Design Group provided the advisory board a presentation on the hydraulics and geomorphology of Zone 4 watersheds. The advisory board then requested preparation of cost estimates for potential conceptual measures identified for East and West Creeks. These were presented to the advisory board on July 25, 2023, and based on feedback from the advisory board at that meeting, Geomorph Design Group has prepared an Executive Summary for Flood Risk Reduction Alternatives at East and West Creek which is posted on the website: https://flooddistrict.marincounty.gov/documents/executivesummary-for-flood-risk-reduction-alternatives-at-east-and-west-creeks/
The advisory board recommended proceeding with design for the East Creek “Medium Plan” and the West Creek “Medium Plan 3-2” as described in the Executive Summary. These Plans represent small-scale creek restoration projects totaling about $2M in implementation cost. District staff indicated they would refine the scope of work for a proposed design contract for these restoration projects and returned to the advisory board for a recommendation to proceed with the project at the January 23, 2024 meeting.
The proposed scope of work is to design and complete environmental review for restoration projects on East and West Creeks. In East Creek this involves preparing plans and specifications for removing accumulated debris and sediment from 50/80 Harriet Way up to Karen Way (approximately 1,320 feet long). This will include design of appropriate biotechnical bank erosion protection through this creek reach. The design engineer may, pending additional feedback from the advisory board at future meetings, also design add-on options (which would increase implementation cost above the estimate) for:
1) installation of a top of bank barrier along 100-130 Leland Way (about 350 feet long),
2) installation of a sediment basin near Karen Way to reduce sedimentation
downstream where it is more difficult to access,
3) plugging or valving of the Town of Tiburon’s 6” storm drain outfall at the Cecilia way crossing, and
4) gating or valving of the East Creek outfalls to the Bay.
In West Creek the scope of work includes design and environmental for the following proposed project elements:
1) Remove rubble (foreign rock and broken concrete) from the creek between SR 131 and 80 Rancho Dr, and Cecilia Way and 180 Rancho Drive.
2) Remove concrete channel stormwater outfall around 143 Blackfield Drive and replace it with a rock lined channel and appropriate biotechnical bank erosion protection,
3) Remove three non-native poplars and one non-native eucalyptus from in-stream, and
4) Stabilize banks (e.g. rock rip-rap) to enlarge channel at location of removed in-channel trees
At the January 23, 2024 meeting the advisory board recommended proceeding with the above describe scope of work with a budget of $400,000.
Update: A staff Civil Engineer is needed to ensure quality of the design. The initiation of this project is on hold until a new Civil Engineer can be recruited to fill a vacancy. The process of recruiting a Civil Engineer is underway, but in these times, it can take many months. We are doing everything we can to expedite this process. Please refer any potential candidates to this website over the coming months: https://www.governmentjobs.com/careers/marincounty
Item 3. Annual and Preventive Maintenance Work Program
Listed below is a summary of annual and preventive maintenance completed this year. In addition to these pre-winter activities, District maintenance crews check the trash racks and pump stations before, during, and after storms. A map of the Flood Zone can be found here for reference: https://flooddistrict.marincounty.gov/documents/map-of-flood-control-zone-4-bel-aire/
For questions, email floodinquiry@marincounty.org.
- Pump Stations
Zone 4 has three stormwater pump stations. Cove Pump Station was installed in 1978 and was significantly upgraded in 2019-2020, Pamela Court was installed in 1990, and Strawberry Circle Pump Station (Zone 4A) was installed in 2003. These pump stations allow the drainage of stormwater from residential and commercial areas to flow into creeks and wetlands where barriers on the banks and shorelines were built to reduce tidal flooding. Each pump station has 2-3 pumps and two forms of power including a back-up generator or back-up propane powered pump.
The County’s Facility Maintenance division conducts preventive maintenance at all pump stations takes every year, including the inspection, testing, and as needed replacement of electrical and mechanical components. Additionally, the County’s Vehicle Maintenance division completes annual servicing of the generators at Cove Pump Station and Strawberry Circle Pump Station, as well as the engine for the Pamela Court Pump Station back-up pump.
Every three years the generators are also load tested. They were last load tested in 2021 so are due for load testing again this summer.
Additionally, individual pumps and motors are typically removed and serviced by a contractor for major maintenance on a six-year interval at each of the Zone’s three stations. The Pamela Ct back-up (propane) pump was removed in summer 2023 for inspection and refurbishment. The pump itself was in good shape but the gearhead needed significant extra work.
Strawberry Circle #1 pump and the Cove #1 pump were removed this summer for major maintenance. Despite being relatively new, both pumps had parts that were severely worn (submersible pump impeller, vertical pump shaft, etc.) that will need to be replaced before putting the pumps back in later this summer before the start of the rainy season. For Strawberry Circle, we are working with our maintenance contractor to determine how lead times and costs compare for these repairs vs. putting in a brand-new pump. Either way, the costs are likely to exceed the $15,000 Zone 4A budget approved this year. The condition reports and extra-work cost description are attached for reference. The #2 pumps in both stations are scheduled for this same maintenance in 2025 and may be in a similar condition.
Recommended Action: Recommend the District Board of Supervisors increase the Zone 4A services and supplies budget from baseline by $8,000.
2. Vegetation and Sediment Removal
In Spring and late-Summer the East Creek access road and Strawberry Circle Pump Station are mowed and vegetation at the Pamela Court Pump Station is trimmed. Likely in August the Conservation Corps North Bay will clear potential flood hazards and remove invasive species of plants while maintaining East and West Creeks. In October cattails will be trimmed. They will also clear vegetation at the debris rack at the end of Karen Way where East Creek flows into the pipes under the road before fall.
Sediment was removed from East Creek in 2022, and typically is needed approximately every 5 years. Staff met with a resident about a suspected bank failure. This turned out not to be a bank failure but rather a minor buildup of sediment on root mass with some light vegetation growing on it. This is typical in creek channels and is likely to scour away with a heavy flow. If not, this sediment will be removed as part of the next sediment removal cycle for East Creek, potentially next year if needed. Meanwhile the situation will be monitored by our storm patrol crew and assessed again in the Spring by an engineer.
Analysis completed as described in Item 2 above suggests that sediment removal on East Creek reduces flood risk, however the District’s programmatic sediment removal on West Creek at Cecilia Way is considerably less beneficial. Based on that, we don’t anticipate continuing the practice of spot-sediment removal in West Creek at Cecilia Way.
3. Programmatic Maintenance Permit Status
After over a decade of coordination, the District received approval from environmental regulatory agencies for a 5-Year Programmatic Stream Maintenance Permit. This work was done primarily by staff, saving a significant amount of money. Listed below is a summary of the key steps and milestones in the process.
In 2011 District staff began working with State environmental regulatory agencies now requiring overarching recurring maintenance permits for local agencies working in waterways. Creek/ditch maintenance activities requiring programmatic permitting include vegetation management, sediment and debris removal, erosion control, maintenance and repair of flood control structures, and levee maintenance. The process began by developing a Stream Maintenance Program (SMP) Manual (see the latest version of it here: https://flooddistrict.marincounty.gov/documents/marin-county-stream-maintenance-manual-2023/) and then applying for permits from relevant agencies, which for most sites includes the CA Department of Fish and Wildlife and the San Francisco Bay Regional Water Quality Control Board.
CA Department of Fish & Wildlife issued a Routine Maintenance Agreement for the District’s creek maintenance that can be viewed here: https://flooddistrict.marincounty.gov/documents/ca-department-of-fish-and-wildlife-creek-maintenance-activities-permit-2021/
The San Francisco Bay Regional Water Quality Control Board (RWQCB) adopted a new Order on July 12 that can be found here:
https://www.waterboards.ca.gov/sanfranciscobay/board_decisions/adopted_orders/2023/R2-2023-0011.pdf
These permits now require that impacts from vegetation and sediment removal be mitigated through activities such as these which must be monitored and reported on to the regulatory agencies for 5 years:
- removing invasive plant species,
- seeding or planting native plants and watering and replacing them if they don’t survive.
These activities increase the cost of doing creek maintenance.
Item 4. County Sea Level Rise Planning Update
The office of the County Executive will send a representative to future advisory board meetings to provide updates on the sea level rise governance structure study underway. Background information on this study can be found in the April 16, 2024 staff report. Related Marin Civil Grant Jury Reports are published at this website:
https://www.marincounty.gov/departments/grand-jury/civil-grand-jury-reports
District staff have no other information on the Grand Jury reports at this time.
Item 5. Greenwood Bay Condominiums
At the April 16, 2024 meeting the Greenwood Bay Condominium HOA President requested a contribution from Flood Zone 4 to a retaining wall restoration project on their property along Saltworks Canal. The staff report from that meeting explained that Counsel advised against a funding contribution because the planned retaining wall does not provide a direct flood benefit. The advisory board requested a written opinion from Counsel; however, County Counsel maintains this position and has nothing to add beyond what was included in the staff report for the prior meeting. (Please find the prior meeting staff report at this web address: https://flooddistrict.marincounty.gov/meetings/zone-4-advisory-board-meeting-april-16-2024/#/tab-agenda-packet)
Item 6. Next Meeting
The next meeting is scheduled for October 22, 2024, at 6:30pm at the Westminster Presbyterian Church.