ML19259B588
| ML19259B588 | |
| Person / Time | |
|---|---|
| Site: | WM-00069 |
| Issue date: | 09/22/2019 |
| From: | Robert Evans NRC Region 4 |
| To: | |
| R. Evans | |
| References | |
| IR 2019001 | |
| Download: ML19259B588 (9) | |
Text
September 22, 2019 MEMORANDUM TO: Docket File WM-00069 THROUGH: Heather J. Gepford, PhD, CHP, Chief /RA/
Materials Licensing and Decommissioning Branch Division of Nuclear Materials Safety Region IV FROM: Robert J. Evans, PhD, CHP, PE, Senior Health Physicist /RA/
Materials Licensing and Decommissioning Branch Division of Nuclear Materials Safety Region IV
SUBJECT:
Observational Site Visit at Maybell Disposal Site On September 4, 2019, the U.S. Nuclear Regulatory Commission (NRC) conducted an observational site visit at the U.S. Department of Energys (DOE) Maybell disposal site in Moffat County, Colorado. This observational site visit was conducted in accordance with NRC guidance dated September 7, 2012. The purposes of the observational site visit were to observe the DOEs routine, annual inspection of the facility, and to observe the physical condition of the site. Enclosed to this memorandum is the NRCs observational site visit report.
In summary, the DOE representatives conducted the annual inspection in accordance with the guidance provided in the Long-Term Surveillance Plan dated April 2008 (Agencywide Documents Access and Management System [ADAMS] Accession No. ML081080326). The disposal cell appeared to be excellent condition. No significant regulatory issues or safety concerns were identified during the site visit.
Docket No.: WM-00069
Enclosure:
NRC Observational Site Visit Report cc: J. Nguyen, DOE Site Manager G. Grice, CDPHE, State of Colorado CONTACT: Robert J. Evans, MLDB/DNMS 817-200-1234
U.S. NUCLEAR REGULATORY COMMISSION REGION IV Docket No.: WM-00069 License No.: General License Pursuant to 10 CFR 40.27 Report No.: WM-00069/2019-001 Licensee: U.S. Department of Energy Facility: Maybell Disposal Site Location: Moffat County, Colorado Date: September 4, 2019 Inspector: Robert J. Evans, PhD, CHP, PE, Senior Health Physicist Materials Licensing and Decommissioning Branch Division of Nuclear Materials Safety Region IV Approved by: Heather J. Gepford, PhD, CHP, Chief Materials Licensing and Decommissioning Branch Division of Nuclear Materials Safety Region IV
Attachment:
Photographs Taken at the Maybell Disposal Site Enclosure
NRC Observational Site Visit Report
1 Background
The Union Carbide Corporation, later known as Umetco, operated a uranium mill at the Maybell site from 1957-1964. The mill processed approximately 2.6 million tons of ore during operations. The ore came from several local open-pit mines.
The milling process produced a radioactive waste material known as tailings material.
The mill tailings were placed in an onsite tailings pile. The Maybell disposal cell was constructed for permanent disposal of the tailings, and other waste material. The U.S.
Department of Energy (DOE) began constructing the disposal cell in 1995. The existing tailings material was reshaped but left in place. During reclamation, the DOE added mill debris, contaminated soil, and vicinity property material on top of the tailings material.
The DOE completed the construction of the disposal cell in 1998.
The Maybell disposal cell is located approximately 5 miles northeast of the town of Maybell, Colorado. The Maybell West heap leach disposal cell is located approximately 0.75 miles west of the Maybell disposal site. There are several open pit mines near the Maybell disposal site. The Rob Pit is located west of the site, and the Johnson Pit is located south of the site.
The disposal cell contains approximately 3.5 million cubic yards of waste material containing an estimated 455 curies of radium-226. The cell covers approximately 66 acres of the 251-acre site. The pentagon-shaped cell measures approximately 1,600 feet by 2,400 feet. The crest is approximately 30 feet above the surrounding terrain.
The disposal cell cover is approximately 7 feet thick, and consists of a radon barrier, frost-protection layer, bedding material (to promote drainage of rainwater), and riprap cover. A rock apron is located at the base of the cell to promote drainage away from the cell. Diversion channels and swales were constructed around the cell for erosion protection, and to channel rainwater away from the cell. Four gullies in the southeastern area were rock armored to help prevent erosion of the gullies. The gullies promote drainage away from the disposal cell into a nearby tributary. Disturbed areas of soil around the cell were regraded, and seeded with native grasses.
The DOE submitted the Long-Term Surveillance Plan (LTSP) for the Maybell disposal site to the NRC in July 1999, and the NRC approved the LTSP by letter dated August 26, 1999 (ADAMS Accession No. ML13254A169). Since 1999, the DOE continued to maintain institutional control of the site under Title I of the Uranium Mill Tailings Radiation Control Act, and 10 CFR 40.27. In accordance with this regulation, the LTSP is required to provide instructions for institutional control of the site. These controls include deed restrictions, site markers, survey monuments, boundary markers, gates, fences, and signs. The physical features of the site are inspected once per year by the DOE staff.
The DOE submitted a revised LTSP to the NRC in April 2008 (ADAMS Accession No. ML081080326). This revision of the LTSP corrected errors in the property boundary. The NRC approved the revised LTSP by letter dated July 11, 2016 (ADAMS Accession No. ML16140A110). The DOE has not revised the LTSP since April 2008.
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During the NRCs 2013 observational site visit of the Maybell disposal site (ADAMS Accession No. ML13239A112), the NRC inspector noted that the physical boundaries did not agree with the legal description of the property due to an inaccurate land survey.
A 2008 real property assessment noted that the 2002 land survey did not match the legal description. As of August 2013, the DOE had not resurveyed the property or updated the site boundary monuments but planned to conduct the survey in the near future.
In the DOEs 2016 Annual Site Inspection and Monitoring Report for Title I sites dated March 7, 2017 (ADAMS Accession Nos. ML17068A191 and ML17068A193), the DOE inspectors discussed the resolution of these property boundary discrepancies. As noted in Section 11 of the 2016 annual report, the Bureau of Land Management confirmed that the perimeter fence along the north, and northwest sides of the site corresponded to the actual site boundary, and that nine boundary monuments, in areas managed by the Bureau of Land Management, had been placed outside of the property boundary. The Bureau recommended to the DOE in 2014 that it should leave the monuments undisturbed to avoid the cost of removing them. The drawing used during the annual inspections was updated at that time to reflect the correct boundary monuments and boundary corners. The NRC staff accepted the resolution of the property boundary discrepancies without comment by letter dated April 12, 2017 (ADAMS Accession No. ML17097A221).
2 Site Status The revised LTSP lists two site-specific concerns involving erosion and seeps. The first concern involves the identification of erosion in the southeastern portion of the property, where several gullies are located. The DOE conducted repairs of the erosion in 2000-2002 which included the addition of rock armor in the gullies. The LTSP specifically requires the DOE inspectors to inspect for erosion, changes in head-cutting or sedimentation deposition in, and around the four rock-armored gullies during each inspection.
The second concern involves the potential for seepage from the disposal cell in the eastern, and southeastern slopes of the cell. Wet tailings material was encountered in this area during construction, and DOE is aware that moisture may seep out of the cell in the future. The LTSP specifically requires the DOE inspectors to look for evidence of seepage in the eastern, and southeastern slopes of the cell during the annual inspection.
The LTSP also requires the DOE inspectors to conduct vegetation monitoring on an annual basis, in part, to ensure that deep-rooted plants do not proliferate the disposal cell cover or surrounding areas.
In May 2018, five quality control monuments were installed on site property in preparation for a baseline aerial survey of the disposal cell. The baseline photogrammetry aerial survey was conducted in September 2018. Multispectral imagery was also conducted to assess vegetation coverage. The DOE plans to conduct additional aerial surveys in the future, for comparison to the 2018 baseline results.
The DOE conducted the previous annual inspection of the Maybell disposal site in August 2018 (ADAMS Accession Nos. ML19066A145 and ML19066A211). The DOE inspection concluded that the disposal cell, diversion channels, drainage structures were 3
in good condition, and functioning as designed. Minor erosion was identified in several locations, but the erosion did not threaten the integrity of the disposal cell. No seepage was identified. Vegetation was treated with an herbicide as needed. One perimeter sign was missing, and was replaced, and the fence was loose or damaged in several locations. No significant maintenance or contingency items were identified during the 2018 inspection.
The groundwater under the Maybell disposal site is designated as limited use, meaning that it is not a current or future potential source of drinking water. The local groundwater is contaminated with naturally occurring radioactive material and other chemicals that exceed the maximum concentration limits established by the U.S. Environmental Protection Agency. The LTSP does not require groundwater monitoring or remediation.
3 Site Observations and Findings To conduct the 2019 site inspection, the DOE inspectors created an inspection checklist.
The checklist included specific instructions for observation of the disposal cell cover, site perimeter, outlying areas, vegetation, and various site-specific features. The inspection staff included the DOE site manager, and two contractors. The contractors had experience in project management, ecology, and geology. The DOE inspectors were accompanied by a representative from the State of Colorado.
At the time of the observational site visit, the property was enclosed by a barbed-wire stock fence and locked gates. Other institutional controls in place at the site included boundary monuments, survey monuments, site markers (Figure 1), and perimeter warning signs. These institutional controls were found to be in good condition, with minor exceptions.
The DOE inspectors checked the disposal cell for evidence of erosion, settlement, slumping, displacement, and any other feature that would require maintenance or repair.
The rock surfaces on the top, and side slopes were found to be in excellent condition (Figures 2-4). Some vegetation was observed on the disposal cell, but this vegetation did not appear to impact the cell cover. No deep-rooted plants were observed on or around the disposal cell. Two slight depressions were noted on top of the cell during 2008, but these depressions have not been identified during subsequent site inspections. These depressions were attributed to inconsistencies in cell construction, and not settlement. No depressions were observed during the 2019 inspection.
Standing water has been identified at the base of the disposal cell during past annual inspections, especially near the base of Gully No. 1. At the time of this inspection, no standing water was observed at the base of the cell (Figure 3).
The DOE inspectors specifically observed the status of erosion and seepage as required by the LTSP. Some minor rills and other signs of erosion were observed, but the DOE inspectors concluded that the erosion appeared consistent with 2018 observations. No seepage was identified in the eastern or southeastern portions of the disposal cell.
The NRC inspector confirmed that the checklist included the inspection requirements as specified in the LTSP, including the seepage and erosion monitoring requirements.
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4 Conclusions The NRC inspector confirmed that the DOE conducted the annual inspection in accordance with the instructions provided in the LTSP, and the associated site checklist.
The tailings cell covers and side slopes appeared to be in excellent condition. Minor erosion was identified around the disposal cell, but this erosion did not appear to be a threat to the disposal cell itself. No significant safety issues were identified during the site visit.
5 Meeting Summary The NRC inspector participated in a pre-planning meeting with the DOE site manager, and the DOE representatives prior to the site inspection. During this meeting, the NRC inspector and the DOE representatives discussed topics such as site status, inspection plan, and potential hazards. The inspector discussed the final site observations with the DOE staff at the end of the onsite visit.
6 Persons Contacted J. Cario, Site Lead, Navarro Research and Engineering, Inc.
J. Doebele, Environmental Protection Specialist, Colorado Department of Public Health and Environment S. Hall, Site Lead, Navarro Research and Engineering, Inc.
J. Nguyen, Site Manager, DOE Office of Legacy Management 5
Figure 1: Maybell disposal site marker at top of disposal cell Figure 2: Top of disposal cell looking east to west Attachment
Figure 3: Gully No. 1, as seen from top of disposal cell, looking southeast Figure 4: Changes in rock between top and side slope of disposal cell, looking north 2
ML19259B588 SUNSI Review ADAMS: Non-Publicly Available Non-Sensitive Keyword:
By: RJE Yes No Publicly Available Sensitive NRC-002 OFFICE RIV:DNMS/MLDB C:MLDB NAME RJEvans HJGepford SIGNATURE /RA/ /RA/
DATE 9/19/2019 9/22/2019