PRLF571_20230905_ Borrow Source Soil Evaluation_DEQ Toxicologist Letter

September 5, 2023
TO: Sean Gallagher Pre-Regulatory Landfill Unit NC Superfund Section RE: Soil Evaluation
NONCD0000571 Albemarle Dump 32311 Nanny Drive Albemarle, NC
Soil from an off-site borrow source was on sampled on July 6, 2023, to determine usability as beneficial fill at the Albemarle Dump. The maximum concentration of each detected chemical was entered into the DEQ Risk Calculator and risks for residential use was evaluated. The cumulative residential (unrestricted) risk exceeded the acceptable risk level for noncarcinogenic chemicals. Therefore, a refinement of this initial, conservative evaluation was conducted.
A statistical program from the United States Environmental Protection Agency (Pro UCL, Version 5.1) was used to estimate the 95 % upper confidence limit (95% UCL) of the mean for sample results of the three chemicals with the greatest risk to future residents. These means were then entered into the DEQ Risk Calculator and risks for residential use was re-evaluated. For the residential exposure
scenario, the calculated hazard index (HI) exceeded the acceptable HI of 1.0 for cobalt (1.9) and iron (1.5). Therefore, the soil from the July 6 sampling event would not be considered acceptable for residential (unrestricted) use.
RECOMMENDATION: The soil does not meet the statutory definition of unrestricted use and
should not be used as beneficial fill. No determination was made concerning compliance with the Pre-Regulatory Landfill Unit sampling logistics, frequency, and comparison to background guidelines.
David Lilley, Environmental Toxicologist Division of Waste Management, NCDEQ