Case Studies Implementing the CASQA IGP Non-Industrial Demonstration Manual (and Expanding Beyond Atmospheric Deposition)
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The CASQA industrial General Permit (IGP) subcommittee, in partnership with Geosyntec Consultants, developed a draft IGP Non-Industrial Demonstration Manual outlining steps for IGP dischargers 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 that these sources are the sole cause of NAL exceedances. This presentation will briefly summarize the flow chart in this manual outlining the evaluation steps along with a brief overview of sampling guidance.  The majority of this presentation will then discuss a real-world case study where the steps in the manual, or similar steps, have been implemented.  In addition, this presentation will provide an overview of other non-industrial and background sources such as parking lots, roadways, buildings, soil, etc., and tips for applying the concepts from the manual to demonstrate whether these sources may be causing NAL exceedances.

The 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, sediments near treated wood utility poles, aerial deposition, and natural background soils.  The hypothesis-driven study will be outlined, including an explanation of how multiple lines of evidence were used to identify non-industrial sources such as dioxin congener fingerprinting and lead isotope analysis.  In addition, off-site sampling of stormwater, pavement solids, and soils near utility poles was also conducted to understand typical dioxins and lead concentrations in stormwater from these sources. The results of this case study, which are applicable to other urban and industrial areas, will be presented and include pavement solids and utility pole soils as potential sources of dioxins exceedances along with atmospheric deposition and pavement solids in high traffic areas as the potential sources of lead exceedances.

We believe that the industrial and municipal CASQA audience will be very interested in this presentation as many permittees are considering background and non-industrial source demonstrations as part of the IGP ERA process.  Not only will this presentation provide guidance on how to develop a robust sampling plan, but it will also present preliminary results for dioxins and lead indicating some potential non-industrial sources, which may be useful if permittees are dealing with high levels of these parameters at their facilities. In addition, this abstract is in line with the conference's theme since identifying what sources of pollutants of concern need to be addressed as water travels from "summit to sea" is an important component of protecting our downstream receiving waters.

Publication Summary

  • Geosyntec Authors: Adam Questad, Maia Colyar, Jared Ervin, Brandon Steets
  • Title: California Stormwater Quality Association (CASQA)
  • Event or Publication: Event
  • Practice Areas: Stormwater and Integrated Water Resource Management
  • Citation: Riverside Convention Center
  • Date: 9:10 - 9:40 a.m. on Wednesday, October 17th
  • Location: Riverside, California