ML24291A080
| ML24291A080 | |
| Person / Time | |
|---|---|
| Issue date: | 11/07/2024 |
| From: | Hayes K NRC/NMSS/DDUWP/URMDB |
| To: | Matt Young US Dept of Energy, Office of Legacy Management |
| References | |
| Download: ML24291A080 (1) | |
Text
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Mary Young, LM Site Manager U.S. Department of Energy Office of Legacy Management 2597 Legacy Way Grand Junction, CO 81503
SUBJECT:
UNITED STATES NUCLEAR REGULATORY COMMISSION STAFF REVIEW OF THE JUNE 2024, 2022, AND 2023 VERIFICATION MONITORING REPORT FOR THE OLD AND NEW RIFLE, COLORADO, PROCESSING SITES
Dear Ms. Young:
The U.S. Nuclear Regulatory Commission (NRC) staff is writing in response to the U.S.
Department of Energy, Office of Legacy Management (DOE-LM) document entitled, 2022 and 2023 Verification Monitoring Report for the Old and New Rifle, Colorado, Processing Sites, dated June 2024 (Received August 5, 2024; Agencywide Documents Access and Management System [ADAMS] Package Accession No. ML24218A161).
The following comments on the Old Rifle Processing Site portion of the report are presented below:
The presence of several Contaminants of Concern (COCs), including uranium, selenium, and vanadium, at elevated concentrations in site groundwater is documented in the above-referenced report. The reported concentrations exceed the Alternate Concentration Limits (ACLs) for each COC proposed in DOE-LMs September 2017 Draft Groundwater Compliance Action Plan (GCAP; ML17268A155) submitted to NRC. The October 2019 Technical Information Request (TIR; ML19284D696) summarized NRCs review of the Draft GCAP and identified potential data gaps and concerns with the September 2017 submittal. The current elevated levels of COCs at the site and the fact that most of the highest COC concentrations were exhibited by monitoring wells not typically included in the routinely monitored wells at the site verifies that a re-evaluation of the site conceptual model and proposed Draft GCAP is needed. NRC concurs with DOE-LMs recommendation to include the non-routine wells in future sampling events for the site to better establish the magnitude and horizontal extent of the dissolved plume.
NRC recommends an evaluation of depth to water/water level elevations and COC concentrations for the site monitoring wells be conducted in conjunction with the on-going GCAP investigation activities for the Old Rifle site. The evaluation may provide additional evidence of the depth, extent, and source strength of potential secondary source zones in the site subsurface.
November 7, 2024
M. Young The following comments on the New Rifle Processing Site portion of the report are presented below:
The groundwater elevation data collected in June and November of 2023 indicate an upward vertical gradient between the deeper well screen of the 0857 monitoring well (screened approximately 19 to 23 feet below ground surface [BGS]) and the shallower well screens of the 0855 (6 to 11 feet BGS) and 0658 (0.5 to 5 feet BGS) wells in the on-site former ponds area (+0.57 feet in June 2023 and +0.32 feet in November 2023).
Groundwater contamination is present in the deeper zoned 0857 well, but at lower concentrations as compared to the shallower wells. The previous Verification Monitoring Reports for 2019, 2020, and 2021 (ML20092G992, ML21133A481, and ML22210A139, respectively) did not include groundwater elevation data for the Old or New Rifle sites. Please include an evaluation of the historical water level elevations for the 0658/0855/0857 well cluster in the seasonal and localized assessment of groundwater flow mentioned as a future evaluation in Section 3.3 of the submittal. The magnitude and extent of vertical hydraulic gradients within the alluvial aquifer during the monitoring period may provide important information related to groundwater flow and transport at the site.
The potential connection of the alluvial aquifer to groundwater discharge from the underlying Wasatch Formation on the northern boundary of the aquifer, also mentioned in Section 3.3, may be of interest to the site evaluation, as well as any connections of the deeper alluvial aquifer zone flow/groundwater discharge into the Roaring Fork Ponds west of the site. Any variations in horizontal groundwater flow direction between the shallow and deeper zones of the alluvial aquifer may also be helpful in characterizing the dissolved plume(s) at the site. Currently, only one on-site well (0857) has a well screen isolated within the deeper portion of the alluvial aquifer.
If you have any questions concerning the NRC review of the report, please contact me at 301-415-0549 or by email at Kevin.Hayes@nrc.gov.
Sincerely, Kevin R. Hayes, P.G., CPG, Hydrogeologist Uranium Recovery and Materials Decommissioning Branch Division of Decommissioning, Uranium Recovery, and Waste Programs Office of Nuclear Material Safety and Safeguards Docket Numbers:
WM-00062 cc: Rifle, CO ListServ List Signed by Hayes, Kevin on 11/07/24
ML24291A080; Ltr ML24291A080 OFFICE NMSS/DUWP/URMDB NMSS/DUWP/URMDB NAME RVonTill KHayes DATE Nov 6, 2024 Nov 7, 2024