DRC-2025-002392

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

July 28, 2025 CD-2025-152

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) –
Notification of BAT Failure, Northwest Corner Evaporation Pond Average
Leakage Rate

Dear Mr. Hansen,

On Friday, July 18, 2025 the Northwest Corner (NWC) Evaporation Pond leak detection
system transducer was replaced on the same day after it was found to be malfunctioning
by the BAT inspector. On Monday, July 21, 2025 it was found that the NWC Pond
system pumped 3,926 gallons over the weekend. EnergySolutions provided verbal
notification of this concern to the Division of Waste Management and Radiation Control
(DWMRC) via e-mail on July 21, 2025 when it was clear the weekly average leakage rate
would exceed the action levels. This letter provides the required 7-day written
notification.

The average daily leakage rate for the week of July 21-27, 2025 was calculated as 567
gallons per day (gpd) for the NWC Pond. As shown in Table 1, these leakage rates
exceed the initial action and allowable average daily leakage rates listed in Parts 4.1.4
and 4.1.5, respectively, of the BAT Contingency Plan (GWQDP Appendix K).

Table 1
Average Daily Leakage Rates – Week of July 21-27, 2025
Evaporation Pond
Calculated
Average Daily
Leakage Rate
(gpd)
Initial Action
Rate
(gpd)
Allowable
Rate
(gpd)
Northwest Corner 567 300 326
gpd – gallons per day

In accordance with GWQDP Appendix K Part 4.1.4, EnergySolutions performed a pump
down test at the pond on July 22, 2025. During the pump down test it was found that the
pump had failed. Maintenance replaced the pump on the same day and the test was
performed again. It was then determined that the leak detection system flow meter was
accurate.

Mr. Doug Hansen
July 28, 2025
CD-2025-152
Page 2 of 2
Due to dry conditions, the water level of the NWC Evaporation Pond is currently very
low. Operational experience has shown that expansion and contraction of the liner caused
by temperature fluctuations can allow water present between the inner and outer liners to
be pushed and to flow into the leak detection system sump, where it is subsequently
pumped by the system. EnergySolutions does not believe the leakage rate exceedance is
related to the upper liner leaking. This is further supported by the relative lack of volume
pumped in previous weeks. Relative to the surface area footprint of the pond, the water
pumped is approximately 0.077 inches.
In the interim, EnergySolutions will continue daily BAT inspections of the NWC
Evaporation Pond to determine if the system continues to pump water.
Please contact me at [phone] with any questions regarding this notification.
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.