ML19092A434
| ML19092A434 | |
| Person / Time | |
|---|---|
| Site: | WM-00067 |
| Issue date: | 04/22/2019 |
| From: | Robert Evans Division of Nuclear Materials Safety IV |
| To: | Heather Gepford Division of Nuclear Materials Safety IV |
| R. Evans | |
| References | |
| Download: ML19092A434 (9) | |
Text
April 22, 2019 MEMORANDUM TO:
Docket File WM-00067 THROUGH:
Heather J. Gepford, PhD, CHP, Chief/RA JFKatanic Acting for/
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 AMBROSIA LAKE DISPOSAL SITE On March 20, 2019, the U.S. Nuclear Regulatory Commission (NRC) conducted an observational site visit at the U.S. Department of Energys (DOE) Ambrosia Lake Disposal Site in McKinley County, New Mexico. 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 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, DOE representatives conducted the annual inspection in accordance with the Long-Term Surveillance Plan (LTSP) dated July 1996. The LTSP can be found on DOEs web site at https://www.lm.doe.gov/Ambrosia/Sites.aspx. No significant regulatory issues or safety concerns were identified during the site visit.
Docket No.: WM-00067 License No.: General License Pursuant to 10 CFR 40.27
Enclosure:
NRC Observational Site Visit Report cc: B. Tsosie, DOE Site Manager S. Rodriguez, NMED Bureau Chief CONTACT: Robert J. Evans, MLDB/DNMS 817-200-1234
Enclosure U.S. NUCLEAR REGULATORY COMMISSION REGION IV Docket No.:
WM-00067 License:
General License Pursuant to 10 CFR 40.27 Report No.:
WM-00067/2019-001 Licensee:
U.S. Department of Energy Facility:
Ambrosia Lake Disposal Site Location:
McKinley County, New Mexico Site Visit Date:
March 20, 2019 Inspectors:
Robert J. Evans, PhD, CHP, PE, Senior Health Physicist Materials Licensing and Decommissioning Branch Division of Nuclear Materials Safety Region IV Stephanie G. Anderson, Health Physicist Reactor Inspection 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 Ambrosia Lake Disposal Site
2 NRC Observational Site Visit Report 1
Background
Phillips Petroleum Company constructed the Ambrosia Lake site mill in 1957 and operated the mill from 1958-1963. The mill processed about 3 million tons of ore. The mill was sold to United Nuclear Corporation in March 1963. United Nuclear Corporation operated the mill for about a month and then discontinued milling operations. United Nuclear Corporation continued to conduct resin ion exchange operations until 1982 when it ceased all site operations.
This site was one of 24 Title I sites identified for remediation in the Uranium Mill Tailings Radiation Control Act of 1978. The U.S. Department of Energy (DOE) started site remediation in 1987 and completed the remediation in 1995. The remediation included consolidation of the tailings material, collection of windblown material, and reclamation of vicinity properties. The tailings and other contaminated materials were encapsulated in a disposal cell. The disposal cell contains 6.9 million tons of contaminated material, consisting of approximately 1,850 curies of radium-226. The disposal cell occupies 91 acres within the approximately 290-acre property.
The cell is roughly rectangular and is about 2,500 feet long, 1,600 feet wide, and 50 feet high. A 30-inch thick radon and radon infiltration barrier made of clayey soil was placed over the contaminated materials. The erosion protection layer consists of a bedding layer and a rock rip-rap layer. The bedding layer is 6 inches thick and the rock rip-rap layer is 6 inches thick on the top slope and 12 inches thick on the side slopes. The top of the cell was built with a 2.5 to 4-percent grade to promote drainage.
A rock apron is located at the toe of the disposal cell. The rock apron varies in thickness between 34 inches to 66 inches. The rock cover extends up to 40 feet from the toe of the disposal cell.
A landfill was constructed in the northeastern corner of the property. According to DOEs records, the landfill contains both non-radiological and radiologically contaminated demolition debris. The landfill is distinguishable only by a slight mound.
The landfill area was reseeded, in part, for erosion protection. A former uranium mine shaft and two vent shafts are located northeast of the main disposal cell. The shafts have been secured to prevent unauthorized access.
The DOE submitted the Long-Term Surveillance Plan (LTSP) for the Ambrosia Lake site to the U.S. Nuclear Regulatory Commission (NRC) in September 1996. The LTSP can be found on DOEs web site at https://www.lm.doe.gov/Ambrosia/Sites.aspx. The DOE also submitted property transfer information to the NRC in September 1998. The NRC approved the LTSP in September 1998 (Agencywide Documents Access and Management System [ADAMS] Accession No. ML14223A558). These actions established the Ambrosia Lake Disposal Site as a Title I site under the general license provisions of 10 CFR 40.27.
Because the groundwater in the uppermost aquifer is not a present or potential future source of drinking water, there are no groundwater monitoring requirements at the site.
In July 1998, the NRC agreed with DOEs determination that the groundwater was not a source of drinking water (https://www.lm.doe.gov/Ambrosia/UAMB00000075.pdf).
3 In 2005, DOE notified the NRC about a small depression on the cover of the disposal cell near settlement plate 4 (ADAMS Accession No. ML051110614). The depression was noted during the first annual site inspection in 1997, and the depression had increased in depth and area since then. There was no evidence that water has ponded in the depression or that damage has occurred to the radon barrier. However, additional settlement could result in ponding and potential damage to the radon barrier. Therefore, DOE proposed to repair the depression during the summer of 2005. The NRC agreed with DOEs proposed construction plan in April 2005 (ADAMS Accession No. ML051120103). The DOE annual inspection report for 2006 (ADAMS Accession No. ML063490237) noted that repairs were completed in August 2005, and the repaired area was in good condition. However, visual observations during the 2008 DOE inspection (ADAMS Accession No. ML090160007) indicated that slight settlement may be recurring. Subsequent inspections by DOE document that additional settlement had not occurred, but DOE staff continues to observe the area during each inspection in case settlement is identified.
At the request of the New Mexico Environment Department, DOE agreed to collect groundwater samples from two onsite wells. Well 0678 is located northeast of the disposal cell. Well 0675 is located south of the disposal cell. At the request of the State of New Mexico, DOE installed a third monitoring well (0409) in May 2011 as part of a regional groundwater investigation. Well 0409 is located adjacent to the disposal cell in the southwestern corner. This well is dry and cannot be sampled.
The DOE agreed to sample these two locations once every three years for up to 30 years. The initial post-closure sampling event was conducted in 2001. At the request of the State of New Mexico, DOE sampled the two wells annually between 2010-2016.
After the 2016 sampling event, DOE returned to a 3-year sampling interval. The next sampling event is scheduled to occur in November 2019.
2 Site Status Groundwater samples were most recently collected by DOE in November 2016, and the results were presented in the Data Validation Package dated April 2017 (https://www.lm.doe.gov/Ambrosia/Documents.aspx). The DOE collected samples from Wells 0675 and 0678. As noted above, Well 0409 was not sampled because it was dry. The sample results indicate that the molybdenum and uranium concentrations in Well 0675 were significantly lower than the two previous sampling events, because the two previous samples were collected at the wrong elevation within the well. The 2016 samples were collected at the correct elevation, the middle of screened area within the well. The uranium (0.85 milligrams per liter) and molybdenum (0.26 milligrams per liter) concentrations in Well 0675 were consistent with historical sample results before the last two sampling events.
The site currently consists of a disposal cell located within an unfenced boundary. There are no structures on the property. The DOE controls site access with an entrance sign and warning signs around the perimeter of the property.
The last annual DOE inspection was conducted on September 10, 2018 (ADAMS Accession Nos. ML19066A145 and ML19066A210). During that inspection, several minor maintenance issues were identified, but no problems were identified that required follow up or contingency inspections.
4 3
Site Observations and Findings The DOE conducted the annual inspection on March 20, 2019, to confirm the integrity of the visible features of the site, to identify any changes in previously identified conditions, and to determine the need for maintenance or additional inspection or monitoring. The DOE staff prepared a checklist to support the inspection. The checklist included requirements to observe the top of the disposal cell, side slopes and apron, outlying areas, and site features such as entrance sign, perimeter signs, site markers, survey and boundary monuments, and monitoring wells (Figure 1).
Overall, the cover of the disposal cell appeared to be in excellent condition. No evidence of cracking, settlement, or slumping was observed. In accordance with the checklist, the DOE staff inspected the area around settlement plate 4, the location where repairs were made in 2005 (Figure 2). Consistent with previous DOE inspections, very minor settlement could be observed, but not enough for definition of the area or measurement of the depth of settlement.
The DOE inspectors were tasked to identify deep-rooted vegetation for treatment with herbicides as well as evidence of animal or human intrusion. No deep-rooted plants or new human intrusions were observed. Evidence of livestock grazing was identified adjacent to the unfenced disposal cell. The inspectors also observed site features including markers, signs, monuments, monitoring wells, and mine shaft/vents.
The DOE inspectors reviewed the area where standing water has been observed in the past along the southern edge of the disposal cell apron. Standing water was identified at this location during the NRCs 2014 observational site visit (ADAMS Accession No. ML14269A181). At the time of the 2019 DOE inspection, no standing water was identified (Figure 3). The DOE has previously determined that the area is a topographic low point and standing water does not impact the integrity of the disposal cell.
In the outlying areas, erosion has been identified in the areas to the north and east of the disposal cell, but the erosion currently has no impact on the integrity of the disposal cell (Figure 4). The DOE inspectors plan to continue to monitor the erosion, for possible repair in the future.
Details about DOEs Ambrosia Lake disposal site inspection, and the anticipated November 2019 sampling event, will be presented to the NRC in the next annual Title I site inspection and monitoring report. This report is expected to be submitted to the NRC in early 2020.
During the site tour, the NRC inspectors conducted independent radiological surveys using a Ludlum Model 19 microRoentgen survey meter (NRC No. 015518, calibration due date of 11/09/19, calibrated to radium-226). With a background of about 10 microRoentgen per hour (R/hr), measurements on and around the disposal cell ranged from 8-14 R/hr. The survey results indicate that the ambient radiation levels at the surface of the tailings cell were at or below background levels. The highest survey measurement (100 R/hr) was measured near a sealed mine shaft (Ann Lee Mine) in the northeastern corner of the property. This elevated survey measurement was attributed to residual mine overburden material and not formerly licensed material.
5 4
Conclusions The NRC inspectors concluded that the DOE inspectors conducted the site inspection in accordance with LTSP and 10 CFR 40.27 requirements. The disposal cell appeared to be structurally intact, and the cover was observed to be in excellent condition. No maintenance needs were identified during the observational site visit.
5 Meeting Summary The NRC inspectors participated in a pre-planning meeting with the DOE site manager and DOE representatives prior to the site inspection. During this meeting, the NRC and DOE representatives discussed topics such as site status, inspection plan, and potential hazards. The inspectors discussed the final site observations with DOE staff at the conclusion of the onsite visit.
6 Persons Contacted E. Holland, Program Manager, DOE Office of Legacy Management R. Johnson, Contractor, Navarro Research and Engineering, Inc.
A. Kuhlman, Site Lead, Navarro Research and Engineering, Inc.
A. Rheubottom, Geologist/Site Lead, New Mexico Environment Department D. Traub, Inspector, Navarro Research and Engineering, Inc.
B. Tsosie, Site Manager, DOE Office of Legacy Management
Attachment Figure 1: Ambrosia Lake disposal site marker at base of disposal cell Figure 2: Top of disposal cell around settlement plate 4, area where depression was repaired in 2005.
2 Figure 3: Southern edge of disposal cell; area where water ponding has been observed in the past; area was dry during the 2019 inspection (looking north)
Figure 4: Erosion located northeast of disposal cell (disposal cell in background, looking south)
ML19092A434 SUNSI Review ADAMS:
Non-Publicly Available Non-Sensitive Keyword:
By: RJE Yes No Publicly Available Sensitive NRC-002 OFFICE RIV:DNMS RIV:RIB C:MLDB NAME RJEvans SGAnderson HJGepford SIGNATURE
/RA/
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/RA JFKatanic Acting for/
DATE 4/4/19 4/5/19 4/22/19