Publication Summary

The Department of Ecology monitored polychlorinated biphenyls (PCBs) from the Walla Walla and College Place Wastewater Treatment Plants (WWTPs) during 2006-2007. The goal was to better characterize PCB loading as discussed in the 2005 Total Maximum Daily Load (Water Cleanup Plan) for the Walla Walla River watershed.

The study findings indicate effluent concentrations are on track in meeting the EPA human health criterion. Both WWTPs are reducing PCB concentrations in influent to effluent samples by two orders of magnitude.

Four influent pipelines to the Walla Walla WWTP were assessed for PCB concentrations, and the relative importance of each is discussed.

This 2006-07 Department of Ecology study presents monitoring results for polychlorinated biphenyls (PCBs) in the influent, effluent, and sewer service networks of the Walla Walla and College Place Wastewater Treatment Plants (WWTPs).

The purpose of the study was to (1) establish whether effluent discharges currently exceed U.S. Environmental Protection Agency (EPA) human health water quality criteria, and (2) assess the extent to which the contamination is internal or external to each facility.

The study was done as a result of PCB wasteload allocations established through a 2005 Total Maximum Daily Load (water cleanup plan) for the Walla Walla River watershed.

The findings of this 2006-07 study indicate that the effluent concentrations are almost meeting the EPA human health criterion for PCBs.

The study assists the Cities of Walla Walla and College Place in identifying PCB sources within their service areas. The cities should continue to identify and clean up likely nonpoint (diffuse) sources of PCBs. This will reduce the influent concentrations of PCBS to the WWTPs as recommended in the Total Maximum Daily Load implementation schedule.

Link to EIM data for User Study ID Brwa0002