DSHW-2024-004081

January 16, 2024
Brandon Cochran, Environmental Project Manager
123 N. College Avenue, Suite 370
Fort Collins, CO 80524
RE:Incident #16594 Release Response Summary and Work Plan
Dear Mr. Cochran.:
The Division received your email with the attachment “Release Response Summary and Work Plan” on November 30, 2023. In order toapprove this workplan designed to address the release near
Lynndyl, Utah, the Division requests that you address the comments below:
Global Comment. The soil samples were screened against the Department of Environmental Response and Remediation (DERR) Leaking Petroleum Storage Tanks (LPST) Tier 1 Screening Criteria.
As outlined in Section 5.2.7 of the Division’s Technical Guide to Risk Assessment (TGRA) (August 2, 2005 (utah.gov)) traditionally, hydrocarbon-impacted soils at sites contaminated
by releases of petroleum fuels have been managed based on their total petroleum hydrocarbon (TPH) content. TPH refers to the total mass of hydrocarbons present without identifying individual
compounds. In practice, TPH is defined by the analytical method that is used to measure the hydrocarbon content in contaminated media. Since the hydrocarbon extraction efficiency is
not identical for each method, the same sample analyzed by different TPH methods will produce different TPH concentrations.
The hazard and health risk assessments that are typically conducted to support risk management decisions at contaminated sites generally require some level of understanding of
thehydrocarbon chemical composition present in the contaminated media.
Traditional TPHmeasurement techniques, however, provide no specific information about thedetected hydrocarbons. Because TPH is not a consistent entity, the assessment of health effects
and development of toxicity values for mixtures of hydrocarbons are problematic.
On that basis, DWMRC assesses risk from TPH by analyzing and assessing the individual chemical constituents rather than relying on TPH fraction data. Use of the DERR Initial Screening
Levels (ISLs) and/or Tier 1 Screening Levels are not appropriate for determining closure under UAC R315-101.
The soil screening criteria listed in the page 4 table should be revised to reflect appropriate United States Environmental Protection Agency (USEPA) Regional Screening Levels (RSLs).
Page 2. The second to last bullet on this page indicates the lateral extent of contamination has been defined in all directions. However, naphthalene in SB-8 is above the residential
RSL, indicating the lateral extent of impacts extends slightly farther to the west, than shown on the figure. SB-13 is for nondetect for naphthalene. While SB-4 was below the residential
RSLs, there may be a data gap in the southwest corner of the site. SB-04 and SB-09 represent the southern part of the spill area, but do not reflect conditions farther west. An additional
boring in the southwest area of the spill may be warranted.
Page 2. The last bullet on this page states that the vertical extent of affected soils was delineated at borings SB-01 and SB-10 and the samples were clean at 4-5 feet below ground
surface (bgs). It is noted that at the 4-5 sample depth for both borings, there were detects for all contaminants of concern, indicating the samples are not clean. Further, naphthalene
was detected equal to the residential RSL in SB-01. Revise the text accordingly.
Page 3, Second Bullet. As noted in Comment No. 1, the Division does not use the DERR LPST screening levels. Please revise the discussion of site data to include a comparison to RSLs.
Page 3, Potential Exposure Pathways. The first bullet lists leaching to groundwater as likely closed. The rational is mostly depth of groundwater. Defining the vertical extent of
contamination is proposed. Please note that under R315-101, the soil-to-groundwater pathway, using soil-to-groundwater screening levels (SSLs) and a dilution attenuation factor (DAF)
of 20. As part of the post remedial report, ensure an SSL evaluation is included. It may be helpful to refer to Section 8.0 of the TGRA on how to conduct this assessment.
Page 3, Human Exposure Pathways and Vapor Intrusion. Please note that risk assessments conducted for the Division must follow Utah Administrative Code (UAC) R315-101. Additional guidance
is available from the TGRA.
Page 4, Second Bullet. While leaching to groundwater may be incomplete, the post removal confirmation data must be compared to SSLs, to confirm the pathway is incomplete.
Page 5, First Bullet. While confirmation samples may include analysis for TPH, the Division will assess closure based on a risk assessment conducted using indictor compounds. Clarify
the analytical methods proposed will be sufficient to assess residual levels of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) are appropriate.
Page 5, Phase 2. Clarify the criteria that will be used to assess if Phase 2 is needed. If confirmation data indicate levels above residential risk-based closure?
Deb – in my section, they would not need a permit to conduct in-situ treatment – this is considered part of corrective action ….
The Work Plan does not address ecological risk. Under UAC R315-101, either an ecological risk assessment must be conducted or a request for an ecological risk assessment waiver must
be provided. Please refer to Section 9.0 of the TGRA.
If you have any questions, please call Erika Greenwell at 385-499-0346.
Sincerely,
Douglas J. Hansen,Director
Division of Waste Management and Radiation Control
DJH/EEG/xx
c:Brandon Cochran, Environmental Project Manager, TRC (Email and Hard Copy) ([e-mail])
Bryan Gilbert, TRC (Email) ([e-mail])
Deborah Ng, Program Manager, DMWRC (Email)
Paige Walton, Program Manager, DWMRC (Email)