Publication Summary

In 2007-2008, the Department of Ecology monitored polychlorinated biphenyls (PCBs) and dieldrin at three wastewater treatment plants (WWTPs) and two abandoned landfills in the South Fork Palouse River watershed.

This study was to (1) establish whether the WWTP discharges exceed EPA human health criteria, and (2) assess landfills as sources of PCBs and dieldrin.

The findings indicate PCB reductions at all three WWTPs, and dieldrin reductions at the Pullman WWTP, are necessary. The soils/sediment and surface water samples from the two landfills contained the contaminants at relatively low levels.

Continued monitoring and limited pollution source tracking measures are recommended.

During 2007-2008, the Washington State Department of Ecology monitored polychlorinated biphenyls (PCBs) and dieldrin at three wastewater treatment plants (WWTPs) and two abandoned landfills in the South Fork Palouse River watershed. This work was done as a result of wasteload allocations recently established through a Total Maximum Daily Load (TMDL) study for the Palouse River.

The goals of this study were to (1) establish whether the Pullman, Albion, and Colfax WWTP discharges exceed U.S. Environmental Protection Agency (EPA) National Toxics Rule (NTR) human health criteria for PCBs and dieldrin, (2) assess if the contamination is internal or external to each facility, and (3) assess two abandoned City of Pullman landfills as sources of PCBs and dieldrin.

All WWTPs were found to reduce influent concentrations of PCBs and dieldrin compared to levels measured in effluents. However, effluent concentrations of PCBs exceeded NTR criteria at the Pullman, Albion, and Colfax WWTPs. Load reductions of 88% (Pullman), 85% (Albion), and 47% (Colfax), are needed to meet the interim wasteload allocations set forth in the TMDL. The Pullman WWTP effluent was the only discharge exceeding the NTR human health criterion for dieldrin. A 48% load reduction is necessary to meet the interim wasteload allocations set forth in the TMDL.

Sediment and soil samples from the abandoned landfills were higher in PCBs than the background river sediment. Dieldrin was detected at low levels in the sediment and soil samples but not in the surface water sample from the upland landfill.

This project assists the three cities in making the first step to quantify PCB and dieldrin concentrations being delivered to and discharged from the WWTPs. A series of recommendations are made to continue (1) pollution-source tracking and (2) reducing sources of PCBs and dieldrin to the South Fork Palouse River.

Link to EIM data for User Study ID BRWA0003