DRC-2025-002020

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

June 24, 2025 CD-2025-132

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

Subject: Groundwater Quality Discharge Permit Number UGW450005 (GWQDP):
Monitoring Well GW-23 – Request for Compliance Status Change Approval

Dear Mr. Hansen:

This letter requests a return to baseline monitoring status for compliance monitoring well
GW-23, presently in probable out-of-compliance (POOC) status for Total Uranium.
EnergySolutions requests the Division of Waste Management and Radiation Control
(DWMRC) provide prompt approval for this well, which has been sampled quarterly (see
Table 1) for Total Uranium since May of 2023 (CD-2024-159), to in-compliance status and a
return to annual sampling. This includes eight consecutive quarters of Total Uranium
concentrations falling below Groundwater Protection Levels (GWPL).

Table 1 lists the GW-23 total uranium Groundwater Protection Level (GWPL), Total
Uranium concentration of each sample, and the corresponding sample date.

Uranium is a naturally occurring radionuclide in Clive Facility groundwater.
Background-based total uranium GWPL exceptions greater than or equal to 0.037 mg/L
have been approved for eight other monitoring wells at the Clive Facility (GWQDP,
2014). The ratio of uranium-234 (U-234) to uranium-238 (U-238) of the 2023 sample is
1.9, which is consistent with historical results from well GW-23 and is also consistent
with the ratio observed for uranium background in groundwater at other Clive Facility
wells. In natural groundwater, the ratio of U-234 to U-238 exceeds 1 (expected by
secular equilibrium) due to an alpha particle recoil effect, in which U-234 is
preferentially mobilized to groundwater from adjacent rock or soil. As a result of the
recoil effect, the ratio of U-234 to U-238 will be higher in natural groundwater than in
contaminated groundwater (Rhodes et al., 2006). EnergySolutions requests a response by
September 1, 2025 to prevent unnecessary continued quarterly sampling.

Should you have any questions regarding this submission please feel free to contact me at
[phone].

Mr. Doug Hansen
June 24, 2025
CD-2025-132
Page 2 of 2
Sincerely,
Mathew R Schon
Manager, Groundwater and Environmental Program
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance
with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry
of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information
submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fine and imprisonment for knowing violations.
Table 1 – Total Uranium in Monitoring Well GW-23
Compliance Status Change to Probable Out-of-Compliance
Sample Collection Date
Total Uranium
Concentration a
(mg/L)
Total Uranium
GWPL
(mg/L)
5/9/23 0.037 0.03
8/17/23 0.0151 0.03
11/28/23 0.0158 0.03
3/25/24 0.0149 0.03
4/8/24 0.0158 0.03
4/8/24 Dup. 0.0149 0.03
9/16/24 0.0165 0.03
9/16/24 Dup. 0.0164 0.03
10/10/24 0.0164 0.03
2/6/25 0.0153 0.03
5/15/25 0.0147 0.03
a Calculated from isotopic uranium data
Bold text = Above GWPL
GWPL = Groundwater Protection Level
mg/L = Milligram per liter