HomeMy WebLinkAboutDSHW-2025-000429Gordo CAP Implementation Report Comments – January 22, 2025
The Division of Waste Management and Radiation Control (Division) has completed its review of the
Corrective Action Plan Implementation Report (Report), dated January 3, 2025, for the Gordo
Property located at Kearns Boulevard and Richardson Flat Road in Park City, Summit County, Utah.
This report was prepared to document a soil removal action.
Based on the review, the Division is providing the following comments:
1. Section 3.1 describes a delineation boundary between boring B-6 and B-7 and between
boring B-7 and B-10 due to the soil in the vicinity of boring B-7 being identified as exceeding
the Toxic Characteristic Leaching Procedure (TCLP) limit for lead. Exhibit 3 in Appendix A
illustrates the locations of the described borings but does not illustrate the delineation
boundary lines between these borings. For clarity, please include a graphic representation
of the delineated boundaries on Exhibit 3 depicting the area containing soils requiring
disposal at the Three Mile Canyon facility.
2. Section 3.2 bulleted item number five states that intermittent perimeter air monitoring for
fugitive dust in the work area was conducted when the impacted soil stockpiles were
excavated to ensure impacted dust was not leaving the site. However, the results of
perimeter air monitoring were not discussed in the report. Please include a brief discussion
of perimeter air monitoring results and associated data collected from the monitoring
activities.
3. Section 5.1 indicates that the carcinogenic risk for an indoor worker and a construction
worker do not exceed 1E-06. However, the carcinogenic risk is reported as 4.56E-06 and
1.66E-06, for the indoor worker and construction worker respectively. Both values are above
the target risk level of 1E-06. Please update the Report to indicate that the cumulative
carcinogenic risks are above the target risk level of 1E-06 for unrestricted closure.
4. Section 6.0 indicates that the 2023 Report did not identify any potential harm from
migration from constituents of potential concern (COPCs) in soil-to-groundwater at the Site.
After reviewing the 2023 Report, several COPCs exceeded the soil screening levels
indicating that the soil at the Site might further impact groundwater. However, the 2023
Report concluded that subsurface native soils in Zone 1 and Zone 2 had not been impacted
by leaching from overlying non-native contaminated soils (Section 5.2) and that remediation
of soils in Zones 1 and 2 will eliminate the potential for future impacts to groundwater. In
order to demonstrate that soil excavation activities did resolve the potential for COPCs to
impact groundwater, confirmation data should be compared to appropriate soil-to-
groundwater screening levels. Refer to Section 8 of the Division’s Technical Guide for Risk
Assessments (TGRA) for guidance. Please revise the Report accordingly.
5. The Report indicates that the confirmation samples were collected from the top two inches
of surficial soil after the excavation. The confirmation samples were then used to determine
the exposure point concentrations (EPCs). When performing a Risk Assessment, specific
soil exposure intervals are used for various receptors as outlined in Section 3.2 of the
Division’s TGRA. The Report does not evaluate the specific intervals for a resident or
construction worker. However, the maximum detected concentration was used in surficial
soils to determine the EPC and is likely the most conservative scenario considering the
known depositional area of mine tailings and soil investigation across the Site. The
confirmation samples, sampling depths, and EPCs are adequate for evaluation of risk at the
Site.
6. The Report does not describe the condition of the site post-remediation. Please revise the
Report to address the final site conditions.
Please submit a written response to comments and a revised report within 60 days of the date of
this letter.