Publication Summary

Sediment from Dillenbaugh Creek, near Chehalis, Washington, was analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs). PCDD/PCDF contamination was found in a half-mile segment of the creek downstream of a former wood-treating facility stormwater lagoon. Although Washington State does not have a numerical freshwater sediment quality limit for PCDD/PCDF, some concentrations were over 100 times the dioxin soil cleanup level.

Upstream of the stormwater lagoon, PCDD/PCDF concentrations were less elevated, suggesting that the contamination may have entered the creek from the lagoon. At some upstream locations, PCDD/PCDF concentrations were still above the dioxin soil cleanup level.

Sediment samples from Dillenbaugh Creek, located in Chehalis, Washington, were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) in April 2004 by the Washington State Department of Ecology. The study was conducted after a 1998 screening-level investigation found that residual PCDD/PCDFs exist in the vicinity of the American Crossarm and Conduit Company (ACC) Superfund site, cleaned up in the late 1980s.

PCDD/PCDF contamination was found in sediment samples in a half-mile segment of Dillenbaugh Creek downstream of the former ACC stormwater lagoon. Concentrations were comparable to those found in the 1998 screening-level investigation. Although Washington State does not have a numerical freshwater sediment quality limit for PCDD/PCDF concentrations, some concentrations from this segment of Dillenbaugh Creek were over 100 times the dioxin level for the cleanup of soils to protect human health.

Upstream from where the ACC stormwater lagoon empties into Dillenbaugh Creek, PCDD/ PCDF concentrations are less elevated, suggesting that the contamination may have entered the creek from the lagoon. At some locations in the upstream segment, PCDD/PCDF concentrations were still above the soil cleanup level for dioxin.

Link to EIM data for User Study ID RJAC006