Numerous studies have been performed at the Site since 2000 as part of the Upper Columbia River site assessment process and RI/FS. Sampling efforts relevant to the current residential soil removal action are discussed below.

2014 Residential Soil Sampling

In 2014, EPA sampled soil at multiple residential properties and tribal allotments in the Columbia River valley between Northport and the U.S./Canada border that may have elevated metals as a result of regional smelter operations. Property owners volunteered to have their property sampled, and the sampling was conducted between August and October 2014.

The results of this investigation indicated that 14 properties and three tribal allotments contained at least one area (i.e., a decision unit) with concentrations of lead over or near the TCRA action level of 700 mg/kg. The average lead concentration from the IC sampling approach for these properties was 985 mg/kg, which is approximately 4 times higher than the cleanup level of 250 mg/kg.  The maximum IC sample lead concentration was 1,936 mg/kg, which is approximately 8 times higher than the cleanup level. The average and maximum IC sample concentrations for arsenic were 52.4 and 103 mg/kg, respectively, which are 2.5 and 5 times the cleanup level for arsenic of 20 mg/kg. Each IC sample was collected from shallow surface soil (usually 0-1” deep), except gardens samples from which were collected from tilling depth (usually 0-12” deep).

2015 Removal Sampling

During EPA's site visit in May 2015, EPA reviewed the DUs from the 2014 sampling event. At certain properties, EPA either extended the boundaries of the DUs, or added new DUs, to ensure that high-risk property areas (i.e., yards or gardens with an elevated risk of potential human contact) were included. From these DUs, EPA collected and analyzed additional samples to further characterize the vertical and horizontal extent of contamination. At each DU sampled in 2014, EPA assumed that the soil at depths from 0 to 6 inches below ground surface (bgs) was contaminated, and new grab samples were collected at depths from 6 to 12 inches bgs. At new DUs, EPA collected grab samples at intervals of 0 to 6 inches and 6 to 12 inches bgs. The samples were analyzed in the field using field-portable X-ray fluorescence (XRF) instruments, with a subset of the samples analyzed at an off-site laboratory.

During the May 2015 sampling event, a total of approximately 480 grab samples were collected and analyzed in the field by XRF, and 100 of these samples were submitted to an off-site laboratory for metals analysis. The results indicated that 80 of the samples exceeded the site cleanup level for either lead or arsenic based on the laboratory data or XRF field screening data if laboratory data was not available. For the laboratory data, lead was detected as high as 1,590 mg/kg, which is 6 times the cleanup level of 250 mg/kg, and arsenic was detected as high as 89 mg/kg, which is 4.5 times the cleanup level of 20 mg/kg.  

• Office trailers have been set up on leased land;
• An equipment and contaminated soil stockpile lay down areas have been established;
• A water extraction permit (from the Columbia River) has been obtained;
• Waste profile samples have been collected and submitted to a laboratory;
• Electric service has been secured to the Command Post;
• Sanitary services have been contracted;
• A security fence has been established around the Command Post and contaminated soil stockpile;
• A site orientation and safety training was provided to all staff.

On July 21, 2015, EPA and the Colville Tribe Business Council (“Council”) held a formal consultation meeting in Nespelem, Washington. Prominent topics discussed in the consultation include the Council’s desire to be informed of and participate in any ongoing and future negotiations between EPA and Teck and the Council’s desire for a long-term cleanup plan for the overall Upper Columbia River Site in general and the tribal allotments in particular beyond the removal in 2015.