Zero-Discharge BMPs: State Parks’ Steps Toward Natural Water Quality Protection in 5 ASBS
Prior to adoption of the 2013 Phase II Permit, California Department of Parks and Recreation (State Parks) did not have permit coverage for regulation of its stormwater discharges to Areas of Special Biological Significance (ASBS). The State Water Resources Control Board’s Exceptions to the California Ocean Plan for Selected Discharges into ASBS, including Special Protections for Beneficial Uses, did not include State Parks as an authorized discharger to ASBS. State Parks is now mandated, under the provisions of the Phase II MS4 General Permit (Phase II Permit), to ensure its discharges do not adversely impact natural water quality. A key step State Parks is currently undertaking is adopting and implementing a number of storm-water-related program management practices and best management practices (BMPs) to protect receiving water quality and comply with the ASBS Special Conditions of the Phase II Permit.
State Parks has 10 park units with 24 parking areas that potentially discharge to ASBS. This presentation will review the results of a BMP feasibility study for these park units and the aggressive retrofit program that is targeting 15 high priority parking lots in 7 of the park units that discharge to 5 ASBS. The 7 parks span from as far south as Crystal Cove State Park, up to Northern California at Del Norte Coast Redwoods State Park. Topics include: hydrological, cultural, and biological site constraints; permitting requirements; Low Impact Development (LID) retrofit conceptual designs; zero-discharge BMPs; maximizing multiple benefits of designs; and operation and maintenance recommendations.
The presentation will cover use of the Phase II LID Sizing tool, developed by the Office of Water Programs, for conceptual-design level sizing of BMPs. This is a web-based tool that allows the user to select and size LID BMPs to comply with the Phase II Permit. The tool allows users to input pertinent parameters such as location, soil type, and impervious areas and provides sizing based on three Phase II-compliant sizing methods. The design goal for each BMP was full infiltration of the 85th percentile design storm, to the maximum extent practicable. Site-specific factors such as native soil type, infiltration rates, offsite flow contribution, depth to groundwater and bedrock, environmental characteristics, and ease of maintenance were considered in advancing designs to the 60% level.
This presentation relates to the conference theme, Stormwater Evolution: Source to Resource, in regards to the design goals of the retrofits: zero-discharge of stormwater runoff via infiltrative, groundwater recharging retrofits and maximizing multiple benefits due to their placement within tourist and recreation areas. The presentation further relates to the Stormwater and Technology track through a discussion of zero-discharge BMPs, which were prioritized for implementation, and how these types of BMPs are designed to target priority pollutants and ultimate Phase II permit compliance. The presentation also directly relates to the ASBS track as the BMPs were selected and designed to protect receiving water quality in 5 ASBS. The presentation will provide for critical discussion with potential collaborators for larger-scale BMP implementation programs. The audience will be stepped through the design thought process for one of the parks, which will provide for an interactive, engaging session.