U.S. ENVIRONMENTAL PROTECTION AGENCY
POLLUTION/SITUATION REPORT
Section 32 Abandoned Uranium Mine (AUM) - Removal Polrep
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Region IX
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Subject:
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POLREP #7
Progress
Section 32 Abandoned Uranium Mine (AUM)
Thoreau, NM
Latitude: 35.4905248 Longitude: -108.0170846
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To:
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From:
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Randy Nattis, On Scene Coordinator
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Date:
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2/25/2013
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Reporting Period:
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2/11/2013 - 2/25/2013
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1. Introduction
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1.1 Background
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Site Number: |
09XN |
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Contract Number: |
EP-S9-12-01 |
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D.O. Number: |
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Action Memo Date: |
10/5/2012 |
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Response Authority: |
CERCLA |
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Response Type: |
Time-Critical |
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Response Lead: |
EPA |
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Incident Category: |
Removal Action |
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NPL Status: |
Non NPL |
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Operable Unit: |
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Mobilization Date: |
10/8/2012 |
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Start Date: |
10/8/2012 |
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Demob Date: |
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Completion Date: |
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CERCLIS ID: |
NNN000908747 |
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RCRIS ID: |
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ERNS No.: |
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State Notification: |
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FPN#: |
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Reimbursable Account #: |
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1.1.1 Incident Category
Removal Action
1.1.2 Site Description
The Site consists of approximately 20 acres, including the mine area and what appears to be a Former Transfer Area approximately 2000 feet to the southwest. The Site is located approximately 1 mile east of County Road 19, Prewitt, McKinley County, New Mexico, roughly 10 miles north of I-40. There is a residence located on the main mine area and both areas of the Site are currently accessible to grazing animals.
AUM 32 is located approximately 1 mile east of County Road 19, Prewitt, McKinley County, New Mexico. AUM 32 is located in an Indian Allotment land which is part of the Casamero Lake Chapter of the Navajo Nation (Latitude: 35°29'26.7576"N, Longitude: -108°1'2.7798"W) and. The Chapter House is approximately 1.4 miles northwest of AUM 32. AUM 32 is in a vacant land surrounded by open space. AUM 32 has approximately 308,632 square feet (sf) of surface Uranium contamination of at least twice investigation level and contains an unsecured deep shaft located in the southeastern portion, and an undetermined extent of underground workings. The mine area is relatively flat with sparse vegetation. Available geographical information show an ephemeral stream or river located north and south of the site which converges approximately 0.25 mile west of the site. A 10-foot deep ditch was observed to run from east to west and bounded the mine area to the north. The ditch connects to a pond located northwest of the mine area.
AUM 32 Transfer Area is located approximately 0.3 miles south southwest of AUM 32. AUM 32 Transfer Area is located in an Indian Allotment land which is part of the Casemero Lake Chapter of the Navajo Nation (Latitude: 35°29'11.94"N, Longitude: 108°1'9.98"W). AUM 32 Transfer Area has approximately 322,592 sf of surface Uranium contamination of at least twice investigation level. The area also contains a concrete pad and a sealed air vent that support mining operations. The AUM 32 Transfer Area is located on a slight elevation with sparse vegetation. Evidence of past water flows toward a northwest direction was observed.
1.1.2.1 Location
Lat: 35.4907656429N, Long: -108.017439362W
1 mile east of CO-19 approximately 10 miles north of I-40 off of Exit 63
Prewitt, New Mexico, 87045
McKinley County
Section - S32
Township - T15N
Range - R11W
Quarter section(s)
NWNE, SWNE, NENE, SENE
1.1.2.2 Description of Threat
Current Site conditions pose ongoing releases and the threat of future releases
of hazardous substances, namely: uranium and its progeny (i.e., radium-226 and radon)
and ionizing gamma and alpha radiation associated with those progeny. The likelihood of direct human exposure, via ingestion and/or inhalation of hazardous substances, and the threat of future releases and migration of those substances, pose an imminent and substantial endangerment to the public health or welfare or the environment based on the factors set forth in the NCP, 40 CFR § 300.415(b)(2).
1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results
In November 2009, U.S. EPA conducted radiation assessments at the Site in coordination with NNEPA. A site screening for AUMs was conducted at the site which included collection of site information and gamma radiation activity (gamma activity) survey data. Gamma activity was measured from surface soil along the initial boundary of the mine areas and along two diagonal intersecting transects from the mine areas’ four corners. Gamma activity measurements ranged from 10,689 to 180,367 counts per minute (cpm) at AUM 32, and 14,322 to 140,917 cpm at AUM 33. A rock from a waste pile at AUM 33 emitted over 800,000 cpm. Gamma activity was also measured from a background location. The gamma activity exceeded two times background which ranged from 16,630 to 17,128 cpm. The building materials in the nearest residence had gamma activity measurements of approximately 12,000 cpm. Based on these results, in 2011 the NNEPA requested assistance from the U.S. EPA in performing a removal assessment of AUM 32 and AUM 33 to determine the nature and extent of the contamination for the purpose of mitigating any potential impacts to human health and/or the environment.
A background area was established 0.45 miles east southeast of AUM 32 and AUM 33 in an area with no suspected impacts from mining. The area is up wind and up slope from all suspected activities and within line of sight to the nearest resident and mining areas. Surface soil samples were collected from random locations within the background area. The sample results and co-located 1-minute gamma activity measurements are presented in Table 4-1. The background Ra-226 concentrations ranged from 0.592 to 0.900 picocuries per gram (pCi/g). The highest Ra-226 background concentration of 0.900 pCi/g was used to calculate the action level for the AUMs. The action level for Ra-226 was based on the sum of the highest background concentration of Ra-226 and the USEPA Preliminary Remediation Goal (PRG) of 1.21 pCi/g.
1.21 pCi/g (PRG) + 0.900 pCi/g (background) = 2.11 pCi/g
The site specific action level for Ra-226 in soil at the AUMs is 2.11 pCi/g.
Based on the 2009 radiation assessment and preliminary gamma activity measurements at AUM 32, AUM 32 Transfer Area, and AUM 33, sampling grids were established. The grid size and number of samples to be collected within each grid were determined using the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM). A total of 68 samples were collected: AUM 32 – 01 through 25, AUM 32– 26 through– 49 (Transfer Area), and AUM 33 – 01 through 16 and AUM 33 WP - 01 through 03.
AUM 32: The sample results (samples AUM 32 - 01 through -25) and co-located 1-minute gamma radiation activity measurements from the AUM 32 mine area are presented in Table 4-2. Ra-226 concentrations in surface soil at the mine area ranged from 1.19 pCi/g to 37.3 pCi/g. Ra-226 concentrations detected down to 4 feet bgs in subsurface soil ranged from 0.787 pCi/g to 112 pCi/g. The soil depths of Ra-226 concentrations exceeding the action level are shown in Figure 4-1. Soil around the open shaft in the mine area contained Ra-226 concentrations above the action level down to depths of 2 to 3 feet bgs. The remainder of the mine area showed Ra-226 concentrations above the action level in surface soil and down to depths of 1 to 2 feet bgs except for AUM-32-04 which slightly exceeded the action level at 3 feet bgs.
AUM 32 Transfer Area: The sample results (samples AUM 32 - 26 through -49) and co-located 1-minute gamma radiation activity measurements from the AUM 32 Transfer Area are presented in Table 4-2. Ra-226 concentrations in surface soil ranged from 0.923 pCi/g to 300 pCi/g. Ra-226 concentrations detected down to 3 feet bgs in subsurface soil ranged from 0.740 pCi/g to 94.8 pCi/g. The soil depths of Ra-226 concentrations exceeding the action level are shown in Figure 4-2. Soil in the area with gamma radiation activity of above 1 million cpm during the survey contained Ra-226 concentrations of 237 pCi/g to 300 pCi/g in surface soil as detected in sampling locations AUM32 -27, -28, and -29. Ra-226 concentrations in sampling locations AUM32 -27 and -28, were above the action level down to 1 foot bgs. AUM32 -29 had elevated levels of Ra-226 up to 3 feet bgs. AUM32 -49 located between the mine and transfer area contained 108 pCi/g of Ra-226 in surface soil and concentrations exceeding the action level down to 2 feet bgs where refusal was met using a hand auger. Except for these four sampling locations, elevated levels of Ra-226 were limited to surface soil (0 to 2 inches bgs). The southern portion of the AUM 32 Transfer Area was bounded by Ra-226 concentrations below the action level.
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2. Current Activities
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2.1 Operations Section
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2.1.1 Narrative
The EPA Emergency Response Section is conducting a CERCLA removal action of uranium mine waste from AUM Section 32 located in the Casamero Lake Chapter of the Navajo nation. EPA is removing the waste from AUM 32 former transfer area and moving it to consolidated stockpile located within AUM 32. The waste at AUM 32 will be excavated and consolidated into one stockpile. This stockpile will then be stabilized with soil tacifier and fenced.
2.1.2 Response Actions to Date - 02.11.2013 - 02.25.2013
During this operational period – EPAand ERRS completed:
Installation of fence around the consolidated pile
2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)
N/A
2.1.4 Progress Metric
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2.2 Planning Section
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2.2.1 Anticipated Activities
- Revisit the site within the next 2 years to monitor the pile for erosion
- Work with NNEPA to ensure a longer term / final solution for the waste pile
2.2.2 Issues
Heavy summer rains
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2.3 Logistics Section
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Site has been demobilized
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2.4 Finance Section
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No information available at this time.
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2.5 Other Command Staff
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2.5.1 Safety Officer
Site has been demobilized
2.5.2 Liaison Officer
OSC Nattis
OSC Nattis will continue to coordinate with locals, the Casemero Lake Chapter, Residents, NNEPA and USEPA
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3. Participating Entities
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NNEPA
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4. Personnel On Site
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Site has been demobilized
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5. Definition of Terms
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CERCLA: Comprehensive Environmental Response Compensation and Liability Act of 1980
DO: Delivery Order
EPA: United States Environmental Protection Agency
ERRS: Emergency and Rapid Removal Services contractor (EQM, Inc.)
μg/hr: Micrograms per hour
μR/hr: Microroentgen per hour
NNEPA: Navajo Nation Environmental Protection Agency
OSC: On-Scene Coordinator
START: Superfund Technical Assessment and Response Team contractor (Ecology and Environment, Inc.)
TDD: Technical Direction Document
AUM: Abandon Uranium Mine
AUM 32: Abandon Uranium Mine Section 32
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6. Additional sources of information
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No information available at this time.
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7. Situational Reference Materials
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No information available at this time.
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