Publication Summary

Monitoring of several point sources believed to be contributing PCBs to the Spokane River was conducted in November and December 1995. The monitoring was a follow up to an investigation conducted during the summer of 1994. The three sources monitored were Liberty Lake Wastewater Treatment Plant, Kaiser Aluminum (Trentwood), and the Spokane Industrial Park.

Monitoring of several point sources believed to be contributing PCBs to the Spokane River was conducted in November and December 1995. The monitoring was a follow up to an investigation conducted during the summer of 1994. The three sources monitored were Liberty Lake Wastewater Treatment Plant, Kaiser Aluminum (Trentwood), and the Spokane Industrial Park.

Data from the Liberty Lake Wastewater Treatment Plant sludge indicate low levels of PCB-1248 in two of three samples with concentrations less than one tenth of the concentration from the single 1994 grab sample. Data from the Kaiser 001 discharge show PCB-1248 concentrations ranging from 0.025 mg/L to 0.034 mg/L, or 19% to 62% higher than in 1994. No PCBs were detected in Kaiser 002 effluent, compared with 1994 sampling which found PCB-1260. Two samples of Spokane Industrial Park wastewater showed PCB-1248 concentrations of 0.055 and 0.043 mg/L. No PCBs had been found in the Spokane Industrial Park wastewater in 1994. With the relatively high flow of the Kaiser outfall 001, the calculated PCB loadings from 1994 and 1995 sampling ranged from 1.7 g/day - 2.3 g/day over both years, more than 30 times the loadings from Kaiser outfall 002 in 1994 and SIP in 1995.

Remediation to remove PCBs from effluent and wastewater at Kaiser and the Spokane Industrial Park is recommended.