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The City of San Jose is responsible for ensuring compliance with Federal and State laws that regulate how stormwater runoff is managed prior to its entry to the storm drain system, streams, rivers or the San Francisco Bay. Specifically, the City operates under the Regional Water Quality Control Board’s Municipal Regional Stormwater NPDES Permit (MRP) that was adopted on October 14, 2009, and became effective on December 1, 2009. The MRP provision (C.3.c. Low Impact Development) goes into effect on December 1, 2011that require that each Regulated Project treat 100% of the design storm runoff with low impact development (LID).
In line with the Municipal Regional Stormwater Permit (MRP), San Jose’s City Council Policy 6-29 :Post-Construction
Urban Runoff Management emphasizes the use of Low Impact Development (LID) measures. LID includes preserving and creating new pervious areas (Site Design), preventing stormwater contact with pollutants (Source Control) and treating runoff with either infiltration, stormwater collection and reuse (Harvesting and Reuse), and/or with landscaped-based treatment measures (Biotreatment). Site design and Source control measures should be used to reduce treatment-requiring runoff as
much as possible to limit the need for expensive treatment measures that require space, piping, and long-term maintenance. For more information, review the document entitled, Using Site Design Techniques to Meet Development
Standards for Stormwater Quality
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For remaining runoff from areas that are not Self-Treating or Self Retaining, the MRP allows the use of Biotreatment stormwater treatment measures if harvesting/reuse and infiltration are infeasible (for reasons including soil infiltration rate, project density, onsite water demand, land use, recycled water use.) The feasibility of particular LID practices shall be determined in accordance with the criteria and procedures set forth in the BASMAA LID Feasibility/Infeasibility Criteria Report.
The following Forms and Worksheets will be used to evaluate the feasibility of LID Stormwater treatment requirements.
San Jose Provision C.3 Data Form (All Regulated Projects)
Infiltration/Harvesting and Use Feasibility Screening Worksheet (All Regulated Projects)
Infiltration Feasibility Worksheet
Rainwater Harvesting and Use Feasibility Worksheet
LID Feasibility Worksheet Attachment 1: Glossary
LID Feasibility Worksheet Attachment 2: Toilet-Flushing Demand Required for Rainwater Harvesting Feasibility
LID Feasibility Worksheet Attachment 3: Santa Clara County Map with Rain Gauge Areas And Soil (Ksat)
The Municipal Regional Permit allows certain types of Smart Growth development to use methods other than the LID practices of infiltration, harvest and use and biotreatment to manage stormwater runoff. Qualifying projects, known as Special Projects, are awarded “LID reduction credits” based on location and density that allow non-LID treatment of a portion of the project’s runoff. The LID reduction credits are intended to allow Smart Growth projects greater flexibility in meeting stormwater treatment requirements, based on the inherent environmental benefits of Smart Growth and potential technical challenges of implementing LID treatment exclusively on high-density sites.
Please confer with your Project Manger to determine if your project meets the Special Projects criteria.
On February 23, 2010, City Council adopted a revised Policy 8-14 and Hydromodification Management (HM) Applicability Map to bring the City’s existing Policy into compliance with the San Francisco Bay Regional Water Quality Control Board’s (RWQCB’s) new Permit. On October 14, 2009, the San Francisco Bay RWQCB adopted a new Municipal Regional Stormwater National Pollutant Discharge Elimination System (NPDES) Permit for the San Francisco Bay Region, including the City of San Jose. Within the RWQCB's newly adopted Permit are new Hydromodification Management requirements for new development and redevelopment projects
The newly adopted City Council Policy 8-14 requires projects that create and/or replace one acre or more of impervious surface that are located within certain subwatersheds and catchment areas to design, build, and maintain hydromodification management control measures that hold and slow down the volume of stormwater runoff coming from a site to pre-project conditions.
City Council Policy 8-14 includes a Hydromodification Management (HM) Applicability Map that shows subwatershed and catchment areas for all of Santa Clara County. |
