DSHW-2024-006652

June14, 2024
Blake Downey
Wasatch Environmental, Inc.
2410 West California Ave.
Salt Lake City, Utah 84104
RE:Comments to theWork Plan for Additional Subsurface Investigation, PTI Property2970 South Richards StreetSouth Salt Lake, Utah84115UTCA-0067
Dear Mr. Downey:
The Division of Waste Management and Radiation Control (Division) has completed its review of the Work Plan for Additional Subsurface Investigation, PTI Property (Work Plan) submitted
on June 4, 2024, by Wasatch Environmental, Inc. on behalf of PTI Properties, LLCfor the Site located at 2970 South Richards Street in South Salt Lake City, Utah (Site).
The Division understands that the objective of the Work Plan is to evaluate the extent of Contaminants of Potential Concern (COPCs) including volatile organic compounds (VOCs), per-
and polyfluoroalkyl substances (PFAS), nitrates, total lead, and total copper in shallowgroundwater at the Site. The following are general comments regarding the investigation of the
COPCs nature and extent at the Site:
The Work Plan indicates that a portion of the concrete floor where a potential source was located will be removed and investigated in the future. The investigation of the concrete floor
and potential source should be a primary concern to mitigate any further contamination of the Site. The Division considers the investigation and removal of any sourceas the highest priority.
Pleaseindicate when the potential source and source material will be assessed and mitigated.
While the Work Plan objective is to define the horizontal extent of COPCs at the Site, the Work Plan also indicates that, “Wasatch recommended that the lateral and vertical impacts of
the chlorinated solvent impacts be defined.” However, the Work Plan does not include assessment of the vertical extent in groundwater. VOCs are naturally more dense than water and are
likely to migrate vertically. Site investigation efforts should includeevaluation of the vertical extent of COPCs at the Site. Please indicate how and when the vertical groundwater
extent of COPCs will be assessed at the Site.
After review, the Division identified the following specific issues in the Work Plan.
Task 2 in the Work Plan outlines the proposed monitoring well construction at the Site. Five shallow monitoring wells are proposed to be screened from 5 to 15 feet below land surface
(ft bls). Historic investigations provided by Wasatch suggest groundwater depth ranges from approximately 7 to 9 ft bls. Forsites with potential chlorinated solvent impacts, the Division
suggests installing monitoring wells approximately two feet below the water table as COPCs are likely to be denser than water. Please provide justification for installing the monitoring
wells from 5 to 15 ft bls or propose new, approximate monitoring well depths based on historic groundwater elevations at the Site.
Task 2 in the Work Plan indicates that Wasatch will survey the new monitoring wells. All monitoring wells at the Site should be surveyed including the existing wells relative to a common
datum so that both existing and newly installed monitoring wells can be used to evaluate groundwater elevations and flow. Please update the Work Plan outlining the survey methodology
and procedures for all existing and proposed monitoring wells at the Site.
While Task 2 of the Work Plan indicates that groundwater samples will be collected using low-flow sampling techniques. However, the Work Plan does not specifically outline the groundwater
sampling procedure. Please include the sampling process including the pump that will be used for low-flow sampling, whether groundwater elevation data will be collected, the management
of groundwater drawdown, purge volume requirements, which geochemical parameters (temperature, pH, dissolved oxygen, specific conductivity, oxidation reduction potential, turbidity)
will be collected and the requirements for reaching stability, and whether the tubing used to sample the monitoring well will be placed in the preferred, middle of the well screen for
sampling VOCs, PFAS, nitrates, total lead, and total copper.
Task 4 of the Work Plan indicates that the off-Site borings to the south are contingent borings based on whether Wasatch determines COPCs are migrating off-Site. Concentrations oftrichloroethylene
(TCE) and Nitrate at GP-9 and tetrachloroethylene (PCE) and Nitrate identified at GP-10 along the southern Site boundary indicate that COPCs have migrated to the southern Site boundary.The
Division suggests these borings be included as part of the investigation and not be contingent. Please update the Work Plan to indicate that the off-Site borings will be included to
assess the extent of COPCs south of the Site.
Task 4 of the Work Plan indicates the southern, off-Site borings will be analyzed for COPCs that exceed their U.S. Environmental Protection Agency (EPA) Maximum Contaminant Level (MCL)
in samples collected from the newly installed MW-5 and MW-6 monitoring wells. The Division suggests sampling the southern, off-Site borings for the same suite of analytes as the monitoring
wells on-Site. Update the Work plan to include what laboratory analysis will be performed to evaluate COPC extent in the off-Site, southern borings.
The Work Plan indicates the objective of the Work Plan is to investigate the extent ofshallow groundwater across the Site. Groundwater samples at GP-10 indicate PCE and Nitrate were
present. Based on the presence of COPCs in the vicinity of GP-10, the Division suggests a Direct Push Technology (DPT) groundwater sample be collected east of GP-10 and south of SM-PT-7
to evaluate COPC shallow groundwaterextent in the southeastern portion of the Site.
Task 5 of the Work Plan outlines the preparation of an Additional Investigation Completion Report and its contents which includes a narrative text, tables, figures, and the analytical
reports. To evaluate the field effort and better understand Site conditions, the Division suggests also including field forms including boring logs, monitoring well construction forms,
and groundwater sampling forms in the Additional Investigation Completion Report.
Please provide a response to these comments by July 15, 2024. If you have any questions, please call Ethan Upton at [phone].
Sincerely,
Paige Walton, Program Manager
Division of Waste Management and Radiation Control
PW/EAU
c:Dorothy Adams, Interim Health Officer, Salt Lake County Health Dept.
Ron Lund, Environmental Health Director, Salt Lake County Health Dept.
Eric Peterson, Environmental Health Deputy Director, Salt Lake County Health Dept.
Blake Downey, Wasatch Environmental, Inc. [e-mail]