DSHW-2025-001207

March3, 2025
Christopher Kaiser
Environmental Supervisor
Tesoro Refining & Marketing Company, LLC
474 West 900 North
Salt Lake City, Utah 84103-1494
RE:Comments on the 2024 Annual Groundwater Monitoring Report;
Marathon Refinery, Remote Tank Farm, and Truck Loading Rack
Salt Lake City, UtahEPA #UTD000826362
Dear Mr. Kaiser:
The Division of Waste Management and Radiation Control (Division) has completed its review of the 2024 Annual Groundwater Monitoring Report (Report), for the Marathon Refinery (Refinery),
Remote Tank Farm (RTF), and Truck Loading Rack (TLR) collectively referred to and located in Salt Lake City, Utah (Site). The Report was prepared by the Antea Group (Antea) and submitted
on February 25, 2025, for the Tesoro Refining and Marketing Company, LLC (Tesoro), a subsidiary of the Marathon Petroleum Company, LP (Marathon).
The Report summarizes the 2024 groundwater, compliance, monitoring activities performed in accordance with the Division approved Corrective Action Plan (CAP) in August 2021 and subsequent
CAP modifications in March and July 2022. Additionally, the Report summarizes the request to partially restart the groundwater recovery system to drawdown groundwater so that an inspection
and subsequent repairs may be performed on a sewer line in in June 2024 (DSHW-2024-006647). Once the sewer line repairs were completed, the Division approved the Partial Groundwater
Recovery Shutdown and Monitoring Plan (DSHW-2024-009688) that approves the system shutdown and outlines a plan to verify that the light non-aqueous phase liquid (LNAPL) observed on-Site
is not from a new source, evaluate whether LNAPL is migrating, and evaluate the potential impact to the dissolved plume on-Site.
After review of the Report, the Division has the following comments that should be addressed in a revised Report:
Table 1 inaccurately indicates that several monitoring wells were “not measured” with the use of abbreviation “NM.” However, many of the monitoring wells were measured but did not have
product in them and should have been labeled “NP.” Please re-evaluate and revise Table 1 to accurately indicate which monitoring wells should be labeled NM or NP.
Tables 2a and 2b summarize the compliance monitoring well’s constituent of potential concern (COPC) concentrations from the May and September 2024 sampling events. After comparing the
concentrations listed in Table 2a and 2b, there are several discrepancies between the Tables and the laboratory results. For example, monitoring well 02A indicates the benzene concentration
is 0.101 milligrams per liter (mg/L). However, the laboratory results indicate a concentration of 0.00148 mg/L. Similarly, benzene concentration discrepancies are observed for MW92-27S
and MW92-29S. Please review all of Tables 2a and 2b and verify that the COPC concentrations coincide with the laboratory results. Additionally, please reviseSection 4 of the text and
all figures accordingly.
If you have any questions, please contact Ethan Upton by email at [e-mail] phone at 385-414-1323.
Sincerely,
Paige Walton, Hazardous Waste Cleanup Section Manager
Division of Waste Management and Radiation Control
PW/EAU/[???]
Enclosures:
c:Dorothy Adams, Health Officer, Salt Lake County Health Dept.
Eric Peterson, Deputy Health Officer, Salt Lake County Health Dept.
Ron Lund, Environmental Health Director, Salt Lake County Health Dept.
James Beardall, Marathon Petroleum Company, ([e-mail])
Chris Kaiser, Marathon Petroleum Company, ([e-mail])
Scarlett Ball, Antea Group, ([e-mail])