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| Title | Spokane River PCB TMDL Stormwater Loading Analysis: Final Technical Report | |||
| Month-Year Published | December 2007 | |||
| Online Availability |
4644 kilobytes, requires version 4.0 or later of Adobe Acrobat Reader Software get Acrobat Reader
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| Short Description |
EPA Region 10 and the Department of Ecology hired Parsons and Terragraphics Inc. to sample the City of Spokane′s stormwater and to refine PCB loading estimates from Ecology′s draft Spokane PCB TMDL (see Related Publications below). Parsons sampled 14 locations within the city during three runoff events. Total PCB concentrations in the stormwater samples varied from 0.062 to 280 ng/L. PCB loads for the entire city were estimated to be as low as 195 mg/day and as high as 687 mg/day, depending on the scenario used to calculate discharge volumes for CSO basins. (Also see abstract below) | |||
| Publication Number | 07-03-055 | |||
| Author(s) | Parsons and Terragraphics Inc. | |||
| Contact | Lubliner, B., (360) 407-7140 | |||
| Print Availability | ||||
| Number of pages | 42 + app (52 total) | |||
| Keywords | basin, loading, river, sampling, Spokane River, stormwater, technical, TMDL, Total Maximum Daily Load, urban | |||
| Subject Waterbodies |
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| Related Publications | Title | Relationship | ||
| Spokane River PCBs Total Maximum Daily Load Study (DRAFT report) | similar topic | |||
| Abstract | Long Description |
The Washington State Department of Ecology conducted a Total Maximum Daily Load (TMDL) assessment for PCBs in the Spokane River from 2003 to 2004 (Serdar et al., 2006). Sampling conducted as part of the TMDL indicated that PCB loads from stormwater runoff in urbanized areas of the City of Spokane delivered significant PCB loads to the river. Given that stormwater is considered the major ongoing contributor of PCBs to the river, it was considered critical to get representative data for loading calculations. The primary goal of this study was to refine PCB loading estimates to the Spokane River from the City of Spokane′s stormwater drainage system. A secondary goal of this study was to begin PCB source identification for future mitigation efforts. To meet these goals, 14 monitoring locations within the City of Spokane′s storm drainage system were sampled during three runoff events. Total PCB concentrations in the stormwater samples varied from 0.062 to 280 ng/L, with an average value of 22.5 ng/L. Combined sewer overflow (CSO) 34 and Union Street stormwater basins showed the highest average concentrations for the three runoff events sampled. PCB loads for the entire city were estimated to be as low as 195 mg/day and as high as 687 mg/day, depending on the scenario used to calculate discharge volumes for CSO basins. It is expected that the true load is somewhere between the low and high estimates. Results from this study indicate that the largest stormwater PCB loads to the Spokane River originate from the Cochran, CSO 34, Union Street, and I05 Upper basins under both scenarios. These basins should, therefore, be prioritized for cleanup activities. |
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