Peel-Caribou Staging Area, Yukon Territory: assessment and remediation of DDT and other contaminants along a riverbank

Abstract

The Peel-Caribou Staging Area, located along the Peel River, northern Yukon Territory, was used for exploratory drilling activities during the mid-1960s. Following abandonment of the project in 1975, waste materials were buried in a pit on site. An encroachment of the river on the waste pit in 1994 exposed the debris along with soils contamiated by DDT (1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane), metals, hydrocarbons, and dichloromethane. The results of subsurface drilling in April 2000 and contaminants analyses, along with data from a geophysical investigation, indicated contaminated soils and debris were located in a 2-metre thick layer below the high-water mark of the riverbank, with an overburden of soil varying in depths from 3 to 4 m. The validation of various field test kits — including immunoassay test kits, PetroFLAGTM analyzer, and photoionization detector — as possible analytical tools for on-site testing was conducted during the site investigations. Site remediation was conducted in January–March 2002 while the river was frozen to facilitate excavations along the frozen and exposed riverbank as well as site access. The debris along the riverbank is usually submerged in the summer and autumn due to fluctuating water levels. Following the construction of a winter overland route to the site, the contaminated soils and associated waste were excavated and transported off-site for disposal. Based on the validation exercise, immunoassay test kits were used for on-site delineation and confirmatory testing during site remediation.