Publication Summary

Priority pollutant metals were analyzed in sediment samples collected in January 1998 from Gibbons Creek remnant channel in the vicinity of Camas-Washougal Industrial Park and the Pendleton Woolen Mill (PWM) land application site. The objectives were to determine the extent and significance of the contamination reported by previous investigators and to determine if the PWM sprayfield was a contributing source. Three industrial park facilities upstream of PWM had been identified as sources of chromium, arsenic, and copper.

The appendices for this report are linked below.

Priority pollutant metals were analyzed in sediment samples collected in January 1998 from Gibbons Creek remnant channel in the vicinity of Camas-Washougal Industrial Park and the Pendleton Woolen Mill (PWM) land application site. The objectives were to determine the extent and significance of the contamination reported by previous investigators and to determine if the PWM sprayfield was a contributing source. Three industrial park facilities upstream of PWM had been identified as sources of chromium, arsenic, and copper.

Results showed that arsenic concentrations increased by an order of magnitude in channel sediments below 32nd Street (upstream limit of contamination) and that zinc, chromium, copper, lead, and cadmium increased by factors of 2–3. The highest arsenic concentration occurred below the 32nd Street storm sewer, which serves Allweather Wood Treaters and Burlington Environmental, previously identified sources of arsenic and other metals. The highest concentrations of chromium, copper, and other metals were found further downstream below the third known source, Exterior Wood, but is probably due to a combination of discharges to the channel. No appreciable elevations were observed in the other metals analyzed: nickel, mercury, silver, beryllium, and selenium. These findings are consistent with results from an earlier survey in 1990. Due to analytical difficulties, no useful data were obtained on antimony or thallium.

Sediments from three of the 12 sites analyzed in the remnant channel had arsenic concentrations ranging from 49–62 mg/Kg, a level expected to have an adverse effect on sediment-dwelling organisms. Sediments at nine sites exceeded the MTCA soil cleanup level for arsenic of 20 mg/Kg. With the exception of one area near the PWM sprayfield that exceeded adverse effects levels for zinc and chromium, and the MTCA soil cleanup level for chromium, other metals were not found in concentrations considered to be a significant concern.

PWM biosolids and sprayfield surface soils had an order of magnitude higher concentrations of zinc and chromium than sediments in the remnant channel and several times higher concentrations of copper. There was equivocal evidence of biosolids being present in the sediments at one location only, Site E at the extreme downstream end of the channel. Sediments at this location had higher zinc, chromium, and copper concentrations than elsewhere in the creek and had zinc:chromium ratios that approached those in sprayfield soils and biosolids. There were no indications that the sprayfield was a source of metals contamination to any other part of the channel.

Samples were examined microscopically to determine if wool fibers could be used as a tracer of the biosolids. Only a few badly deteriorated fibers were identified at Site E, and none could be conclusively identified at other locations adjacent to the sprayfield. The analyst concluded that the fibers were poor tracers of the biosolids because of their low mobility once applied to soil and finite life in the environment.

Selected sediment samples were analyzed for petroleum and the pesticide dieldrin, a chemical of concern at PWM. A high concentration of total petroleum hydrocarbons (TPH), estimated at 40,000 mg/Kg, was identified in the sediments at Site E. This appeared to be lube oil. The MTCA cleanup level for TPH in soil and industrial soil is 200 mg/Kg. It was not possible to determine if oil may have contributed to the elevated metal concentrations seen at this site. No dieldrin was detected in the sediments at detection limits of 1.2-3.2 ug/Kg, a finding in keeping with historical data.