DSHW-2025-000421

January 22, 2025
Gary Brown, Environmental & Petroleum Compliance Manager
Teton Petroleum Transport
P.O. Box 50602
Idaho Falls, Idaho 83405
RE:Technical Summary Report Teton Petroleum Transport Spill
Utah State Highway 24 Milepost 24
Loa, Utah 84747Spill No. 16688
Dear Mr. Brown:
The Division of Waste Management and Radiation Control (Division) has reviewed the Technical Summary Report Teton Petroleum Transport Spill (Report) outlining the tanker truck fuel release,
investigation,corrective measures, and restoration activities on Utah State Highway 24 Mile Post 45 located inLoa, Utah for the spill that occurred on September 27, 2023 (DSHW-2024-008999).
The incident was reported to the Utah Department of Environmental Quality Divisionof Environmental Response and Remediation on September 27, 2023(SpillNo. 16688).
Section 5.4 of the Report indicates risk to humans from contaminated soil is an incomplete pathway. However, a highway maintenance or construction worker may be subject to exposure to
residual levels of contamination in soil if repairs are made to the adjacent roadway. Therefore, soil is a potentially complete exposure pathway and per Utah Administrative Code R315-101-5(d)(4),
should be evaluated.
Constituents of potential concern (COPCs) left in soil after corrective measures were completed were compared to the U.S. Environmental Protection Agency (USEPA) Regional Screening Levels
(RSLs) for a construction worker. The exposure pathways evaluated included inhalation of fugitive soil particulate, dermal contact, and incidental ingestion. The maximum detected concentrations
in soil, regardless of location at the site, was conservatively used as the exposure point concentration. The results of the screening levels risk assessment were a carcinogenic risk
of 3E-09 and a hazard index (HI) equal to 6E-03. Both the carcinogenic risk and HI are below the Division’s unrestricted land use thresholds of 1E-06 and less than or equal to 1, respectively.

Prior to determining closure, a soil-to-groundwater migration pathway evaluation should be performed using the USEPA RSL soil screening levels (SSLs) and a dilution attenuation factor
(DAF) of 20. Residual levels of COPCs in soil are below the SSLs, indicating residual levels of contamination in soil are protective of groundwater.
An Ecological Risk Assessment Waiver was requested and is approved in accordance with Utah Administrative Code R315-101-5(j)(3)(ii) based on the lines of evidence provided in the Report.
The spill location being adjacent to a highway is not a viable habitat for potential ecological receptors
Based on the cumulative risk for the spill area is below the threshold of 1E-06 for carcinogenic risk and less than or equal to a HI for noncarcinogens for current and future receptors
based on actual land use, there are no current or potential future impacts to groundwater, and an ecological risk assessment waiver was granted, the site meets the criteria for corrective
action complete without controls.
The Report is hereby approved and Spill No. 16688 closed.
If you have any questions, please contactGabrielle Marinickby email at [e-mail] or by phone at 385-499-0172.
Sincerely,
Douglas J. Hansen, Director
Division of Waste Management and Radiation Control
DJH/GEM/wa
c:Nathan Selin,Health Officer, Central Utah Public Health Department
Eric Larsen, Environmental Health Director, Central Utah Public Health Department
John Chartier, P.E., District Engineer, UDEQ
Gary Brown, Environmental & Petroleum Compliance Manager, Teton Petroleum Transport
(Email and Hard Copy)[e-mail] Tabor, Project Manager, EN-TECH (Email) [e-mail] Burrows, Region 4 Stormwater Program Coordinator, UDOT
(Email)
[e-mail] Walton, Division of Waste Management and Radiation Control, UDEQEthan Upton, Division of Waste Management and Radiation Control, UDEQ