A New Statistical Methodology: Using subcatchment monitoring data to prioritize placement of stormwater treatment controls
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This article presents a transparent, reproducible, robust, and defensible statistical methodology for siting source controls and structural treatment controls (or best management practices [BMPs]) throughout a watershed based on water-quality monitoring data.

The methodology was developed and tested on two watersheds at the Santa Susana Field Laboratory in Ventura County, CA, with stringent National Pollutant Discharge Elimination System (NPDES) numeric effluent limits (NELs) for stormwater runoff that apply at the watershed outlet compliance monitoring locations (or outfalls). Constituents of concern (COCs) include total suspended solids (TSS); 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); tetrachlorodibenzo-p-dioxin toxic equivalence (TCDD TEQ); and total and dissolved lead (Pb), copper (Cu), cadmium (Cd), and mercury (Hg). For environmental, permitting, and constructability reasons, "end-of-pipe" treatment options at the study area outfalls are not feasible; therefore distributed solutions throughout the watershed are necessary. However, monitoring data must be processed to prioritize such controls. The statistically rigorous approach presented here was applied on an annual basis to evaluate stormwater subarea monitoring data to determine where treatment controls will be most effective. Local background stormwater pollutant concentrations are also computed and considered in the analysis to focus control placement on areas that are above background. The intended outcome of the resulting implementation activities is to reduce COC concentrations and NEL exceedance frequencies using targeted upland source control and distributed BMP placement.

Publication Summary

  • Geosyntec Authors: Megan Otto, Paul Hobson, Rita Kampalath, Brandon Steets
  • All Authors: Megan Otto, Paul Hobson, Rita Kampalath, Brandon Steets, Robert Pitt, Jon Jones, Michael Stenstrom, Robert Gearheart, Michael Josselyn, Debbie Taege
  • Title: A New Statistical Methodology: Using subcatchment monitoring data to prioritize placement of stormwater treatment controls
  • Event or Publication: Stormwater Magazine
  • Practice Areas: Watershed and Stormwater Management, Water and Natural Resources Assessment, Management, and Restoration
  • Date: 2013
  • Type: Publication (Printed)