Broader Stormwater Management Efforts

Overview of the Broader Stormwater Management Efforts in San Bruno

Understanding Local Flooding and Infrastructure Dynamics

The localized flooding along 7th Avenue is a significant concern, and while the City’s 2014 Storm Drain Master Plan does propose increasing storm drain capacity along Angus Avenue, this strategy alone may not resolve the flooding issues on 7th Avenue. This is due to the hydraulics and capacity, where increasing the pipeline's ability to carry water without enhancing the discharge capabilities can lead to exacerbated flooding downstream, particularly when the discharge is affected by tidal or channel restrictions, flow back-charging, and the challenges posed by rising sea levels.

Collecting street runoff and quickly diverting it downstream to larger bodies of water is the older, traditional approach for managing stormwater. This is how much of development occurred during the postwar housing boom. What this has led to is less absorption of rainwater into the ground and larger volumes of surface water being reliant on increasingly larger pipelines to be captured and diverted downstream. A new paradigm shift is occurring to increase the capture and infiltration of rainwater before it enters the pipeline or creating diversions within the system. This has the effect of not only reducing the volume of stormwater in the pipelines, but also the added benefit of replenishing the groundwater supply.

This is a link to a recent article prepared by CalMatters: Can CA capture more stormwater? It's an untapped resource - CalMatters. 

Grant funding is increasingly being tied to “green infrastructure” projects. The City has received grant funding from multiple governmental organizations for the Regional Stormwater Capture Project at I-280/I-380. Grant funding for “gray infrastructure” projects, like those to increase capacity, are increasingly rare.

These are generational issues that were created by longstanding practices and policies. These generational issues cannot be undone quickly or easily.

Detailed Concerns Addressed

o Cupid Row Drainage Channel Overflow: The Cupid Row area has seen flooding due to flow back-charging from the drainage canal which has affected the Belle Air school, 4H Club, and 7th Avenue area. This overflow illustrates the challenges of managing stormwater in periods of heavy rain combined with high tidal levels, highlighting the need for comprehensive drainage capacity management.

o Flooding Near Caltrain Tracks: The maintenance of pump stations by Caltrain along Huntington Ave. and 1st Ave. is vital for preventing underpass flooding. Previous incidents have largely been due to pump station operational issues rather than infrastructure capacity or flow back-charging.

o Culvert Flow Capacities: The Storm Drain Master Plan identifies upsizing or adding culverts but without addressing the discharge capacity, increasing flow capacity may not solve the flooding issue. The system's maintenance is continually assessed to ensure optimal performance and manage back-charging effectively where possible.

o Public Works Storm Response Protocol: Our Public Works Operations team employs a rigorous storm response protocol, encompassing pre-storm preparations and responsive actions during and after events. This includes cleaning and maintaining storm drains, managing sandbags, and addressing any storm-induced emergencies, as demonstrated during the recent President’s Day weekend storm.

o Update on Infrastructure Work in the Avenues: The Avenues 2-1 and 2-2 Sewer and Water Replacement Project is near design completion and is scheduled to begin construction in Summer/Fall 2024. Work includes replacing the sewer main on 7th Avenue between Belle Air Elementary School and 6th Avenue.

Partnership with OneShoreline and Innovative Solutions

The City of San Bruno is responsible for stormwater collection and maintenance within its boundaries. After leaving San Bruno, stormwater enters the jurisdiction of San Mateo County, Caltrans, and San Francisco County. Flooding issues often occur near the City's eastern exit points—such as Cupid Row, East Angus Ave., Pine Ave., San Bruno Ave., and Walnut Ave. near 7th Ave.—due to system back-charging and insufficient drainage channel capacity. High tidal heights or water levels in the drainage channel exacerbate these issues, preventing proper drainage and leading to flooding, as seen with Cupid Row overflowing into Belle Air school and nearby areas. This problem typically arises during extended rain periods or when a large amount of rain falls in a short timeframe, combined with high tidal heights or drainage channel water levels. Unfortunately, the challenges of flooding at this location will require a regional commitments and partnerships to achieve our community’s desired solution: to address the flooding issue in the area.

Therefore, a crucial aspect of our approach involves our partnership with OneShoreline, the Flood and Sea Level Rise Resiliency District formed in 2020. They are updating the hydraulic models and assessing their pump stations, particularly those affecting the Belle Air neighborhood, to better understand and address the complex dynamics of flooding in our community. OneShoreline's efforts, detailed in the information linked below, represents a collaborative and forward-thinking strategy to manage stormwater effectively.

Funding Challenges and Local Efforts

The City has attempted to procure grant funding (e.g., National Oceanic and Atmospheric Administration Climate Resilience Regional Challenge Grant, State of California’s Coastal Conservancy Grant, San Francisco Bay Restoration Authority Grant, and the U.S. Environmental Protection Agency’s San Francisco Bay Water Quality Improvement Fund) to perform some of the improvements identified in the Storm Drain Master Plan but was advised that the grant administrator was unlikely to award gray infrastructure projects.

The City also attempted to secure local funding for storm drain infrastructure and flood protection, which was not successful in 2021. This outcome reflects the challenges in aligning community support and resources towards comprehensive infrastructure improvements. Despite this setback, the City remains committed to identifying alternative funding sources and strategies to address our stormwater management needs, leveraging state and federal grants and exploring innovative solutions that align with our environmental and community goals.

The partnership with OneShoreline underscores a shift towards innovative stormwater management practices, aiming to develop solutions for issues that cross multiple jurisdictional boundaries and be competitive for funding.

Next Steps

The challenges of stormwater management in San Bruno, from infrastructure limitations to the nuances of local and regional flooding, demand a multifaceted and proactive approach from various partners and stakeholders. Our commitment to addressing these issues, in partnership with organizations like OneShoreline and through the adoption of innovative management strategies, is unwavering. We value your engagement and encourage ongoing dialogue to ensure our community is informed, prepared, and resilient in the face of these challenges. While we continue to work on the various efforts above, one main missing component is adequate funding for the stormwater at the local level to help further drive the current initiatives. Our current stormwater enterprise fund is in the negative balance every year as our stormwater fee has not increased in three decades. Even with the current partnerships and initiatives, the City lacks the funding to address this generational issue.

Based on known needs, fixing the City’s stormwater system is estimated to cost $85,000,000. However, further efforts must be made to identify all of the needs and costs that will fully address the issues.

We thank you for your continued interest and concern for our community’s well-being. The City would love nothing more than to help "fix" the problem. However, a generational problem will require a generational solution, and we are committed to helping the community achieve the resolution it deserves and desires.

Attachments

OneShorelines's Efforts