ML24355A199
| ML24355A199 | |
| Person / Time | |
|---|---|
| Site: | WM-00070 |
| Issue date: | 12/23/2024 |
| From: | Robert Evans NRC/RGN-IV/DRSS/DIOR |
| To: | |
| References | |
| Download: ML24355A199 (1) | |
Text
December 23, 2024 MEMORANDUM TO: Docket File WM-00070 THROUGH:
Jeffrey E. Josey, Chief Decommissioning, ISFSI, and Operating Reactor Branch Division of Radiological Safety and Security FROM:
Robert J. Evans, PhD, Senior Health Physicist Decommissioning, ISFSI, and Operating Reactor Branch Division of Radiological Safety and Security
SUBJECT:
NRC OBSERVATIONAL SITE VISIT AT THE MONUMENT VALLEY PROCESSING SITE, ARIZONA On December 10-11, 2024, a U.S. Nuclear Regulatory Commission (NRC) inspector conducted an observational site visit at the U.S. Department of Energys (DOE) Monument Valley Processing Site in Apache County, Arizona. This observational site visit was conducted in accordance with the guidance provided in NRC Inspection Procedure 89060, Department of Energy Observational Site Visits. The purpose of the site visit was to observe DOEs routine, annual groundwater sampling efforts at the Monument Valley site. Enclosed to this memorandum is the NRCs trip report for this observational site visit.
In summary, DOE representatives conducted the annual groundwater sampling in accordance with the instructions provided in DOEs Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites, dated September 2024. No significant regulatory issues or safety concerns were identified during the site visit.
Docket No.:
WM-00070 License No.:
General license pursuant to 10 CFR 40.27 cc w/
Enclosure:
J. Tallbull, DOE Site Manager B. Goretzki, Bureau Chief, AZ Department of Services
Enclosure:
NRC Trip Report CONTACT: Robert J. Evans, DRSS/DIOR 817-200-1234 Signed by Josey, Jeffrey on 12/23/24
ML24355A199 SUNSI Review By: RJE ADAMS:
Yes No Sensitive Non-Sensitive Non-Publicly Available Publicly Available Keyword NRC-002 OFFICE SHP:DRSS:DIOR BC:DRSS:DIOR NAME REvans JJosey SIGNATURE
/RA/
/RA/
DATE 12/20/24 12/23/24
Enclosure U.S. NUCLEAR REGULATORY COMMISSION REGION IV Docket No.
WM-00070 License No.
General license pursuant to 10 CFR 40.27 Report No.
WM-00070/2024-001 Licensee:
U.S. Department of Energy Facility:
Monument Valley Processing Site Location:
Apache County, Arizona Dates:
December 10-11, 2024 Inspector:
Robert J. Evans, PE, CHP, PhD, Senior Health Physicist Decommissioning, ISFSI, and Operating Reactor Branch Division of Radiological Safety and Security Approved By:
Jeffrey E. Josey, Chief Decommissioning, ISFSI, and Operating Reactor Branch Division of Radiological Safety and Security
Attachment:
Photographs taken at the Monument Valley Processing Site
2 NRC Trip Report
1 Background
The Monument Valley Processing Site (Figures 1 and 2) is located in Apache County, Arizona, approximately 15 miles south of Mexican Hat, Utah. The site is situated on the western side of Cane Valley on property controlled by the Navajo Nation. A uranium ore upgrader operated near the site from 1955-1964. A uranium mill was constructed and operated at the site from 1964-1968. During milling operations, the site included the mill and associated equipment, ore storage area, two tailings piles, heap leach pads, batch leaching area, and evaporation pond.
The mill and related equipment were removed after the facility was shut down in 1968.
The U.S. Department of Energy (DOE) subsequently conducted surface reclamation from 1992-1994. Approximately 1.3 million tons of tailings and associated wastes were removed from the Monument Valley site for disposal at the Mexican Hat Disposal Site.
The ground water underneath the site was contaminated during milling operations. The soils located underneath the former tailings piles may continue to be a source of groundwater contamination. The contaminants of concern include uranium, nitrate, and sulfate. Site-related contamination has been identified in the groundwater over a mile downgradient from the mill site.
2 Site Status The three main aquifers, in descending order, are the alluvial, Shinarump, and De Chelly aquifers. The three aquifers are unconfined in some locations, resulting in leakage between adjacent aquifers. In certain areas, the nitrate and uranium levels in the groundwater exceed the maximum concentration levels established by the U.S.
Environmental Protection Agency (EPA) in Title 40, Code of Federal Regulations (40 CFR), Part 192. Because a maximum contaminant level has not been established by EPA for sulfate, DOE established a cleanup goal for sulfate at the request of the Navajo Nation.
In response to the contaminated groundwater, DOE developed and issued a draft groundwater compliance action plan (GCAP) in August 1999 (Agencywide Documents Access and Management System [ADAMS] Accession Nos. ML20210T367 and ML20210T397). The draft GCAP proposed selected remediation methods and monitoring requirements.
The original monitoring program included sampling 25 wells in the alluvial aquifer and four wells in the De Chelly aquifer. No monitoring wells were recommended for the Shinarump aquifer since this aquifer apparently was not contaminated from site-related activities. The corrective action program, as described in the 1999 GCAP, included groundwater monitoring, natural attenuation, phytoremediation (use of plants to remediate contaminated groundwater), active remediation (pump-and-treat), and institutional controls. The DOE also planned to conduct a series of tests to determine the best combination of treatment methods for cleaning portions of the aquifers. Although DOE issued the draft GCAP and implemented some portions of the proposed corrective action program, DOE did not finalize the document.
3 Since the last observational site visit of the Monument Valley site in December 2016 (ML16347A311), DOE issued a pilot study in July 2018 (ML18218A347), a GCAP work plan in January 2019 (ML19008A178, not publicly available), a collaboration report in June 2022 (ML22174A329, not publicly available), and a GCAP work plan addendum in June 2022 (ML22174A374, not publicly available). The work plan and associated addendum provided instructions to obtain more information to support development of a revised GCAP. Due to the COVID-19 pandemic, DOE skipped the annual sampling event in 2020 (ML20309A962).
At the time of the NRC observational site visit, the groundwater remediation strategies in effect included groundwater sampling, natural attenuation (natural flushing), and institutional controls. The number of wells sampled has changed over time for various reasons. The results of annual sampling are managed by the DOEs Geospatial Environmental Mapping System (GEMS) which can be found at https://gems.lm.doe.gov/.
3 Site Observations and Findings (IP 89060) 3.1 Observation of Site Activities (Risk Module RM-01)
The DOEs contractors conducted the annual sampling event at the Monument Valley Processing Site during the week of December 9, 2024. The DOE planned to sample 62 monitoring wells and two surface water locations. The work was being implemented by three teams with two individuals on each team. The inspector observed portions of the sampling event and discussed the sampling protocols with the samplers. (Figures 3 and 4). The inspector compared the sampling methodology used by the samplers to the instructions provided in DOEs Sampling and Analysis Plan, revision 16.7 (https://www.energy.gov/sites/default/files/2024-09/S04351-16.7_SAP_0.pdf).
Prior to the onsite sampling event, the samplers established a matrix which included wells to be sampled and analytical test requirements for each sample. The samplers measured the water levels in the wells and conducted field measurements as required by the Sampling and Analysis Plan. These field measurements included alkalinity, dissolved oxygen, oxidation-reduction potential, temperature, specific conductance, pH, and turbidity.
The inspector noted that the samplers used calibrated equipment and flushed the sampling equipment as necessary after each use. The samplers collected the required number of duplicate samples as required by the Sampling and Analysis Plan, and water filtration was used as stipulated in the Plan. The samplers appeared knowledgeable about the tasks being performed and the requirements specified in the Sampling and Analysis Plan. Problems, when encountered, were entered into the samplers electronic logbook.
The inspector observed the sampling of a continuous multichannel tubing well (Figure 5).
The instructions for these wells were provided in a program directive that was an attachment to the Sampling and Analysis Plan. These wells have various ports (Figure 6) that allowed for collection of groundwater samples at different elevations. The data can be used to monitor the groundwater quality at different depths across the aquifer.
4 During the site tour, the inspector observed the physical condition of the processing site.
Access to the site was controlled with fences, locked gates, and signs. No significant areas of erosion were identified. The former processing site was fenced, in part, to keep livestock out of the area.
3.2 Public Doses, Effluent Release, and Environmental Monitoring (Risk Module RM-02)
The information provided in GEMS indicate that nitrate and uranium continue to exceed the EPAs groundwater standards at certain wells. For example, the uranium concentration in monitor well 662, located within the fenced area, was approximately 0.7 milligrams per liter, with an EPA maximum concentration level of 0.044 milligrams per liter. For comparison, the uranium concentrations at the upgradient, background well 602 was recently measured at 0.00344 milligrams per liter. Several residences are located immediately to the east and south of the processing site. As part of DOEs interim corrective action program, a domestic water supply system was installed in the early 2000s to provide potable water to local residences.
4 Conclusions The DOEs contractors conducted sampling activities in accordance with the guidance provided in the Sampling and Analysis Plan. The inspector confirmed that the DOEs contractors implemented the procedure requirements for sample collection, calibration checks, filtration, and quality assurance. The samplers appeared knowledgeable about the tasks being performed.
5 Meeting Summary The inspector participated in a safety meeting with the DOEs lead sampler and site manager prior to the site visit. During this meeting, the participants discussed topics such as site status, potential site hazards, hydration, and cold weather risks.
A final exit briefing was held with DOEs representatives and the NRC project manager on December 16, 2024. The inspector provided DOE representatives with several potential program enhancements for its consideration. The participants also discussed which documents were considered proprietary information.
6 Persons Contacted E. Au, Intern, RSI EnTech, LLC G. Baer, Environmental Scientist, RSI EnTech, LLC C. Carter, Environmental Scientist, RSI EnTech, LLC B. Deans, Hydrogeologist, Navajo AML D. Fatt, Office Specialist, Navajo AML C. Grammer, Environmental Scientist, RSI EnTech, LLC D. Lee, Senior Environmental Scientist, Navajo AML N. Solawetz, Field Operatoins Lead, RSI EnTech, LLC J. Tallbull, Site Manager, DOE Office of Legacy Management A. Tiga, Environmental Scientist, RSI EnTech, LLC
Attachment Figure 1: Monument Valley Processing Site entrance gate sign Figure 2: Monument Valley Processing Site, looking south
2 Figure 3: Monitor well sampling in progress Figure 4: Bottles of groundwater collected for analysis of different analytes
3 Figure 5: Collecting water sample from Continuous Multichannel Tubing Well 903 Figure 6: Sampling ports in Continuous Multichannel Tubing Well for different elevations