Challenges of Locating Water Capture Projects at School Sites
The Town of Atherton, in cooperation with the with the Las Lomitas Elementary School District is developing a water capture project on the campus of the Las Lomitas Elementary School. The project is being funded through a Cooperative Implementation Agreement (CIA) with Caltrans and implements a concept envisioned by the San Mateo Countywide Water Pollution Prevention Program (SMCWPPP). It is a clear example of building bridges among agencies to solve multiple local problems while treating stormwater as a resource.
The Town of Atherton is a member of the SMCWPPP, a program of the City/County Association of Governments of San Mateo County (C/CAG). SMCWPPP supports C/CAG’s member agencies in complying with requirements contained in the second five-year term of the Municipal Regional Permit (MRP) issued by the San Francisco Bay Regional Water Board. The MRP requires San Mateo County permittees to reduce PCBs by 370 grams per year by June 30, 2020, with an interim reduction of 60 grams per year required by June 30, 2018, with a minimum of 15 grams per year of the total to be achieved via green infrastructure. Permittees also must demonstrate they have reduced mercury by six grams per year via green infrastructure by June 30, 2020. These reductions will be accomplished partially through stormwater capture and use and/or infiltration to groundwater. This project will help implement the countywide Storm Water Resource Plan (SWRP) that focuses primarily on storm water capture with a multi-benefit approach to overall water resources planning, including water quality.
The project will include a diversion structure to re-direct all dry-weather urban runoff and the first flush of wet-weather runoff from the Atherton Channel through two pre-treatment devices to remove trash, debris, and sediment before conveying the water into two (2) buried multi-chambered storage/infiltration facilities with a targeted storage capacity of seven (7) acre-feet. Depending on the results of a geotechnical analysis, engineered dry well(s) on the bottom of the storage chambers are proposed to be constructed to facilitate infiltration.
The Las Lomitas Elementary School project will initially involve an evaluation of how to best achieve the multiple objectives of 1) capturing dry weather runoff in order to eliminate the transport of mercury, PCBs, trash and other pollutants to San Francisco Bay during dry weather; 2) capturing at least the first flush of wet-weather runoff to reduce the load of pollutants transported downstream to the Bay during wet weather, and 3) diverting potential flood flows from the Atherton Channel that flows beneath Alameda de las Pulgas and the campus.
The project will capture discharges from a tributary area of approximately 1,177 acres, split between four jurisdictions. (The approximate drainage areas are: 319 acres from Atherton, 306 acres from Menlo Park, 389 acres from Woodside, and 163 acres from Stanford University property.) This water capture facility will greatly assist Caltrans and the municipalities to come into compliance with the Mercury and PCBs TMDLs by reducing the transport of these pollutants downstream to San Francisco Bay.
Pursuant to a memorandum between the Town and the School District, day-to-day management of the design and construction of the project will be handled by the School District in coordination with the Town because the project is on the school site and will go the State Architect as a change to an existing school construction project.
The audience will be provided with information about how projects may be implemented on school campuses by developing a mutual understanding of agency needs and working together to develop projects of mutual benefit. The presentation should engage audiences because of the unique management of the project and the fact that there have been very few municipal projects in California developed on school sites.
Richard Watson, an urban and regional planner based in Mission Viejo, has been active in CASQA since its inception. He is a former CASQA Board Member, current EPC member, and Co-Chair of the Watershed Management & Impaired Waters Subcommittee. He is the principal consultant for the Los Cerritos Channel Watershed Management Program, and a sub-consultant on two other WMPs. Rich is heavily involved in stormwater funding, and co-authored the LA County Funding Options Report. He was instrumental in securing funding for four water capture projects in the Los Cerritos Channel Watershed, as well as projects in two other watersheds.