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The Contra Costa County GI Plan is a section of the Municipal Regional Permit (MRP) that requires the County to develop and implement a long-term plan to incorporate low impact development measures to treat stormwater on both public and private lands. It targets streets and roads, parking lots, and other hardscapes. The focus of the County’s GI Plan is the integration of stormwater treatment into County-owned buildings, parking lots, and road rights-of-way. Its purpose is to provide a blueprint for how the County intends to gradually transform its urban landscape and storm drainage systems to treat polluted stormwater by allowing it to flow through stormwater treatment facilities (i.e., bioswales and bioretention basins) that remove many urban pollutants before they enter the storm drain system.
GI refers to constructing and retrofitting storm drainage systems to mimic natural processes by enabling stormwater to infiltrate the soil rather than to runoff into storm drains and pipes. This relatively new approach is being used to reduce runoff volumes, disperse runoff to vegetated areas, harvest and use runoff where feasible, promote infiltration and evapotranspiration, and use bioretention and other natural systems to detain and treat runoff before it reaches tributary creeks and, ultimately, the San Francisco Bay. GI facilities include, but are not limited to, pervious pavement, infiltration basins, bioretention facilities, green roofs, and rainwater harvesting systems. GI can be incorporated into construction of new and redeveloped parcels, roads, and other infrastructure within the public right-of-way.
The GI Plan provides a long-term blueprint for implementing GI throughout the County over a 20-year period (2020 to 2040). This plan is largely based on the Contra Costa County Stormwater Resources Plan (SWRP), which was finalized in September 2018. The SWRP developed a comprehensive set of watershed and water quality goals/objectives, a preliminary evaluation framework for the GI Plan and GI project priorities, and a preliminary list of potential stormwater management projects. The SWRP is intended to facilitate development and implementation of stormwater management projects for the County that will provide multiple benefits to improve water quality, reduce localized flooding, increase water supplies for beneficial uses, and enhance the environment and the community. The projects identified in the SWRP have been refined and prioritized through the GI Plan for projects that best fulfill one or more of these four categories:
1. Treatment of both public and private land in unincorporated County contaminated with PCBs, Mercury, and other identified pollutants that are regulated by a Federal Total Maximum Daily Loads program;
2. Treatment of County-owned properties in both unincorporated County and cities that had industrial land uses prior to 1980 (referred to as “Old Industrial” in the MRP);
3. Treatment of County-owned properties in unincorporated County and also in cities, along with County roads that had urban land uses prior to 1980 (Old Urban) in the MRP; and
4. Multiple benefit GI, i.e., projects that help fulfill urban greening, water quality, water supply, flood control, and habitat restoration goals, connections to trails, safe-routes-to-schools, recreation, and traffic-calming through “green streets.”
These categories served as the primary criteria to evaluate the approximately 200 potential GI project locations that were identified in the SWRP. These were winnowed over the course of the GI planning process to the 30 GI project locations/priorities that will appear in the final GI plan (as shown in Attachment 1). The GI Planning process began in the fall of 2018 and is concluding this summer (Attachment 3).
The County Watershed Program convened a GI Plan Technical Advisory Group (TAG) to review, comment, and edit both text and potential GI project locations provided in early drafts of the GI plan. The TAG met four times over the course of the planning process and was composed of 12 representatives from all Public Works Department’s divisions, as well as from those of the Department of Conservation and Development. The TAG helped to refine the potential GI project opportunities from 100 to the 30 that will be shown in the Final GI plan.
The administrative final Contra Costa County GI plan is provided in Attachment 4. The final GI plan will be released on July 19 and will be available to the Board of Supervisors for its review and approval on August 6. The final GI Plan will be submitted to the Regional Water Quality Control Board as part of its MRP annual report in September 2019. |