Case Study: Low Impact Development Retrofit at Pillar Point Air Force Station

Low Impact Development (LID) is a modern sustainable design approach that is currently being embraced as an efficient stormwater management practice by a wide range of regulatory agencies. By retaining and infiltrating (or filtering) runoff at the source, this approach promises a reduction of peak runoff rates, volumes, and pollutant loads. Although LID is becoming widely accepted, additional research is required to further develop the understanding of its effectiveness as a stormwater management approach. An effective method for enhanced understanding is through the development, observation, and monitoring of case studies where LID is employed as a stormwater management strategy. Such is the case at a remote auxiliary military installation, Pillar Point Air Force Station (PPAFS), located in Half Moon Bay, California. This paper documents an effort by the United States Air Force (Air Force) to implement LID concepts to minimize impacts of a storm water discharge from PPAFS to the Pacific Ocean. The effort was initiated in response to a waste discharge prohibition of the California Ocean Plan (COP) and the fact that the discharge is into a sensitive habitat, designated in California as a Area of Special Biological Significance (ASBS). The project has required an extensive understanding of the regulatory requirements of governmental agencies, environmental concerns of non-governmental organizations, and various interests of local stakeholders. Several engineering alternatives were considered as corrective actions and a thorough selection process was undertaken to engage interested stakeholders and determine a preferred alternative. Although this process is ongoing, the LID concept has been vetted as the primary focus of the preferred alternative. This project will provide a unique opportunity to develop, observe, monitor, and evaluate the effectiveness of a specific LID design. Additionally the COP waste prohibition affects hundreds of discharges along the one third of California Coastline designated as ASBSs; this effort will set a precedent for other dischargers as an efficient and relatively cost effective way to address COP compliance.