DRC-2025-000260

299 South Main Street, Suite 1700 ▪ Salt Lake City, Utah 84111
[phone] ▪ Fax: [phone] ▪ www.energysolutions.com

January 22, 2025 CD-2025-013

Mr. Doug Hansen, Director
Division of Waste Management and Radiation Control
P.O. Box 144880
Salt Lake City, UT 84114-4880

Re: Groundwater Quality Discharge Permit Number UGW450005 (GWQDP):
Monitoring Well GW-58 – Exceedance and Compliance Status

Dear Mr. Hansen:

In accordance with Part I.G.2 of the GWQDP, EnergySolutions is providing notice of an
exceedance for the uranium-234 (U-234) concentration in groundwater at compliance
monitoring well GW-58.

Table 1 lists the GW-58 U-234 Groundwater Protection Level (GWPL), U-234
concentration, and the sample collection date for both the original sample and the
duplicate taken at the same time. Well GW-58 is currently in POOC status for total
uranium, and the U-234 concentration exceedance was observed in the 4th quarter 2024
POOC sample. The radiological analytical data report for well GW-58 was received by
EnergySolutions on January 14, 2025.

Table 1 – U-234 in Monitoring Well GW-58
U-234 GWPL
(pCi/L)
U-234 Concentration
(pCi/L)
Sample Collection
Date
31.2 31.7 10/10/2024
DUP: 31.2 28.1 10/10/2024
GWPL = Groundwater Protection Level
pCi/L = Picocuries per liter

Uranium is a naturally occurring radionuclide in Clive Facility groundwater.
Background-based uranium-234 GWPL exceptions have been approved for four
monitoring wells at the Clive Facility, including well GW-58. The ratio of U-234 to
uranium-238 (U-238) of the sample is 2.2, which is consistent with historical results from
well GW-58 and is also consistent with the ratio observed for uranium background in
groundwater at other Clive Facility wells.

Mr. Doug Hansen
January 22, 2025
CD-2025-013
Page 2 of 2
EnergySolutions believes the observed GWPL exceedance in well GW-58 is due to
analytical variability and the condition where the background uranium concentration and
the GWPL for the well are numerically similar. This is further supported by the uranium
isotopic ratio discussed above and data from the duplicate sample, collected at the same
time, reporting below GWPL.
Per Part 1.G.2.b, EnergySolutions will continue quarterly sampling and analysis for
isotopic uranium at well GW-58. The next quarterly sample will be collected during the
first quarter 2025.
Should you have any questions regarding this submission please feel free to contact me at
801-649-2060.
Sincerely,
Mathew R Schon
Manager, Groundwater and Environmental Program
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of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information
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