Remedial Action & Investigation, Caton Island, Alaska

Brice performed a remedial action of lead-contaminated soil and a remedial investigation at a former FAA radio range facility located on Caton Island, Alaska. Prior to excavation, we located historical sample locations for each area of concern (AOC) with concentrations greater than the 2019 preliminary ACLs with a GPS. We used historical sample locations, along with field observations and field screening data to help define excavation boundaries. Lead-contaminated soil was removed using an excavator, was placed in 1-cy supersacks, and weighed to meet the helicopter’s carrying capacity of one ton. The bags were transported by helicopter from the AOC to the barge staging area and transported by barge to a permitted facility for disposal.

During the removal action, Brice performed cultural resources monitoring, detailed archaeological monitoring, and data-recovery to satisfy Section 106 obligations in accordance with a memoranda between the FAA, the State Historic Preservation Officer, USFWS, and the Pauloff Harbor Tribe; the DOI ARPA archaeological investigation permit; and the mitigation and treatment plan. Prior to fieldwork, our senior archaeologist delivered a field and project management team archaeological awareness briefing to ensure compliance and clarity on the sensitive archaeological aspects of field execution. To mitigate impact to archaeologically sensitive areas, we used tundra mats to minimize ground disturbance or damage.

While in the field, our archaeologists worked alongside the field crew to mitigate adverse impacts, and to prevent unanticipated and unaccounted impacts to cultural resources. We used an excavator with a “butter bar”—a flat, toothless blade welded across the teeth of the excavator bucket that allowed for scraping a broad area down 5 to 15 centimeters. We performed mechanical excavation methodically to allow proper identification of artifacts and archaeological features within the excavation area.

Brice also performed a remedial investigation at several areas of concern to investigate XRF screening results that exceeded the ACL for lead that had not been confirmed to be below the ACL with an analytical sample. We performed soil sampling, an XRF lead investigation, installed two monitoring wells, and performed groundwater sampling.

Caton Island is a remote and austere location requiring a temporary life support camp. The field crew mobilized/demobilized to Caton Island by helicopter from Cold Bay, Alaska.