Case Studies Implementing the CASQA IGP Non-Industrial Demonstration Manual (and Expanding Beyond Atmospheric Deposition)
The CASQA industrial General Permit (IGP) subcommittee hired Geosyntec Consultants to develop the IGP Non-Industrial Demonstration Manual to provide a clear, consistent, and defensible methodology for IGP dischargers to use to evaluate whether their numeric action level (NAL) exceedances are likely attributed to atmospheric deposition sources. The Manual also outlines steps for developing a sampling plan as part of the Level 2 Exceedance Response Action (ERA) Action Plan to demonstrate whether non-industrial sources are the sole cause of NAL exceedances. This presentation will briefly summarize the Manual’s methodology along with a brief overview of sampling guidance. The presentation will then focus on case study projects where this methodology has been implemented for non-industrial sources beyond atmospheric deposition. The presentation review other non-industrial and background sources such as parking lots, roadways, buildings, and soils, as well as tips for applying the concepts from the Manual to develop multiple lines of evidence to demonstrate whether these sources may be causing NAL exceedances.
One case study will include Boeing’s Santa Susana Field Laboratory (SSFL) located in eastern Ventura County. Stormwater discharges are regulated through an individual industrial NPDES permit that includes Water Quality Based Effluent Limits (WQBELs) for multiple pollutants. Despite the implementation of multiple stormwater treatment controls, monitoring results at some outfalls have occasionally exceeded WQBELs. In response, a study was developed to evaluate the contribution of non-industrial pollutant sources to stormwater runoff including solids deposited on paved parking lots and roads, soils near treated wood utility poles, aerial deposition, wildfire ash, and natural background soils. The hypothesis-driven sampling design will be described, including an explanation of how multiple lines of evidence were used to identify non-industrial sources, including use of forensic tools such as dioxin congener fingerprinting and lead isotope analysis. The results of this study, which are applicable to other urban and industrial areas, will be presented. Other datasets will be summarized including background (or reference watershed) stormwater concentrations for iron and magnesium from multiple Southern California datasets.
Given the large number of IGP dischargers that are experiencing NAL exceedances for pollutants that have reasonable potential for background demonstration (e.g., iron and magnesium), we expect the industrial CASQA audience to be very interested in this topic, and to wish to incorporate the presented material into their own ongoing background and non-industrial source demonstrations as part of the IGP ERA process.
This abstract is in line with the conference’s theme since identifying industrial stormwater pollutant sources is a critical first step necessary to develop an effective control strategy to protect our downstream receiving waters.