U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Navajo Abandoned Uranium Mine Site Screen Report This form is for use at the site of abandoned uranium mines (AUM) located on Navajo Nation lands. Applicable sites include all mine and mine features that have or have not undergone reclamation by the Navajo Abandoned Mine Lands Reclamation Program, including features, adits, pits and waste piles. Applicable sites also include all AUM sites listed in the USEPA CERCLIS database, all sites listed in the 2008 AUM GIS Report issued by USACOE and USEPA, all AUM sites on allotment lands associated with the Navajo Nation, and any and all AUM sites not listed in any database located on Navajo lands. Reconnaissance of any sites located on lands adjacent to Navajo lands that may be impacting Navajo lands will need to be coordinated with the authorities appropriate to those lands. The purpose of the form is to ascertain the status and location of the identified A UM site, and record all immediate site information associated with the mine site. Decisions and recommendations on what additional steps are needed will be provided on a separate document. Silentman 1 AUM Site Navajo AUM Northern Region Prepared by: Weston Solutions, Inc. Contract: W91238-06-F-0083 12767.063.496.1111 August 2010 Silentman 1, Mine ID # 62 1 August 2010 ------- U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Part I Site Identification, Location and Status Site Names and ID numbers as applicable Mine ID: 62 Map ID: N16 CERCLIS: NNN000908966 Navajo Abandoned Mine Land Reclamation Program: NA-0927 Local name / Aliases: None Chapter and local area: Teec Nos Pos Chapter County: Apache State: Arizona Lat/Long: 36.908156323 N/-109.3020386 W Nearby road and highway: Highway 160 Local Post Office: Teec Nos Pos Surface Land Status: check one or more and provide ownership and contact information below Tribal Trust Land ^ Public lands Q Private Q Tribal Fee Land Q Bureau of Land Mgmt Q Allotment Q State O Fee land Q Subsurface Mineral Rights: No information on subsurface mineral rights ownership was found in the EPA/AUM Database. Claim and operator information: The mine site surface land status is classified as Tribal Trust Land. Historical documents showed the operator of the mine as Harold Broshears in 1958. No other historical ownership / lease information was identified in the EPA/AUM database. Number of residential structures within 200 feet of mine: None Estimated volume of mine waste onsite: None Silentman 1, Mine ID # 62 2 August 2010 ------- ¦G.S. Environmental Protection Agency Region IX, San Francisco Navajo AtlM Project Part II Summary of radiological readings Highest gamma radiation measurement: 61,501 counts per minute (cpm) Describe any other radiological measurements: A total of 1,804 gamma radiation measurements were collected from the mine site, ranging from 5,095 cpm to 61,501 cpm. Measurements collected in the vicinity of the reclamation caps were found at levels ranging from approximately 20,000 cpm to 60,000 cpm. The measurements are represented in Figures 1 and 2. Background Locations Average background = 11,042 cpm #1 11,042 cpm Distribution Chart and Statistics: The following chart and statistics were generated by ESR1 ArcGIS 9.3.1, and show the general distribution of the site gamma radiation measurements. The horizontal X axis represents the gamma radiation reading levels in cpm (lowest levels to the left). The vertical Y axis represents the frequency of each gamma radiation level. 8 o o o o o o 100-- 50-- u —r 1 1— 1 5095.00000 19196.50000 33298.00000 47399.50000 61501.00001 Count: Minimum: Maximum: Sum: Mean: Median: Standard Deviation: 22588860.00000 5095.00000 61501.00000 12521.54102 11362.00000 6400.43160 1804 Silentman 1, Mine ID # 62 3 August 2010 ------- U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Part III Status of Reclamation and Mine Waste The following information was obtained from the Navajo Abandoned Mine Land Reclamation Program (NAMLRP) Point Features Database: NAMLRP Status of the mine site: Reclaimed : Yes Waste Pile onsite : No NAMLRP Project Number: NA-0927 NAMLRP Mine features: 2 Rim Strip / Pits The following information was obtained from field observations collected during the 2010 site screening: Provide description and status of all mine sites and features at site. Include all waste piles, adits, pits and other features, and indicate whether they are open, closed, covered, capped, buried or unreclaimed. Indicate approximate size, shape and extent, including description of any reclamation caps. Note condition of all caps. Observed reclamation work and status: Adits None Waste Piles None Pits None Shafts None Other Debris and Mine Features 2 reclamation caps: 50' x 20' x 2'; 15' x 10' x 0.5' Silentman 1, Mine ID # 62 4 August 2010 ------- U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Part IV Site observations and Environs Observed Structures: list number of and describe human habitation status of structures at the following distances from mine: 0 to 200 feet: None 200 feet to 0.25 mile: Observed Public or commercial structure: list and describe all schools, clinics, Chapter Houses, places of business and any other structure used by members of the community at the following distances: 0 to 200 feet: None 200 feet to 0.25 mile: None Levels measured around the perimeter(s) of the identified structure(s): Consistent with background levels Observed water sources: list the number and type of wells and surface water sources that are potentially used for human consumption at the following distances from the mine: 0 to 0.25 miles: None 0.25 miles to 4 miles: None Sensitive environments: note and describe all sensitive environments located within visible range of the mine site, including: wetlands, endangered species, habitats and approximate locations of sites that may be under protection of the government of the Navajo Nation. None Known Site History: include information from interviews with Chapter officials and residents. Note information on mine ownership, type of mining operation, period of operation, known amount of production, and any other information as provided. Silentman 1 mine consists of an area of 14,963.28m . The mine was identified as being operational in 1958. Historical documents showed the operator of the mine as Harold Broshears in 1958. While operational, the mine had a total reported production volume of 12 tons. No other historical information or any additional ownership / lease information was identified in the EPA/AUM database. Silentman 1, Mine ID # 62 5 August 2010 ------- U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Part V Response Action Summary SiteName(s): Silentman 1 Chapter: TeecNosPos Decision Criteria Is there an unreclaimed waste pile at the site? No At what distance from the waste pile is the nearest residential structure located? None At what distances from the waste pile are there potential drinking water sources? None Is there a reclamation cap or sealed adit in place at the site? Yes Is the cap/seal functionally intact? Yes Is the cap/seal sufficiently degraded to create a concern about releases? No At what distance from the cap/seal is the nearest domestic structure located? At what distance from the cap/seal is the nearest domestic drinking water source? None Summary of emergency response factors None Summary hazard ranking system factors None Summary of reclamation factors Reclamation caps Silentman 1, Mine ID # 62 6 August 2010 ------- ¦G.S. Environmental Protection Agency Region IX, San Francisco Part VI Photos Navajo AtlM Project Photo 2. Silentman 1 site, reclamation cap Silentman 1, Mine ID # 62 7 August 2010 ------- ¦G.S. Environmental Protection Agency Region IX, San Francisco Navajo AtlM Project Photo 3. Silentman 1 site, reclamation cap Silentman 1, Mine ID # 62 8 August 2010 ------- U.S. Environmental Protection Agency Region IX, San Francisco Navajo AUM Project Part VII Contacts Reports and Information Name: Stanley Edison (928) 871-6861 Eugene Esplain (928) 871-7331 Title or official role (if any) Navajo EPA Superfund Program Address PO Box 2946. Window Rock. AZ 86515 Information provided Lead Regulatory Agency Name: Title or official role (if any) Name Title or official role (if any) Telephone number Information provided Name Title or official role (if any) Telephone number Information provided Silentman 1, Mine ID # 62 9 August 2010 ------- Figure 1 - Gamma Radiation Measurements, Above Two Times Background Silentman 1 (62) Teec Nos Pos Chapter, Navajo Nation Legend Gamma Radiation Measurements • < 2X Backgound > 2X Background Gamma survey conducted 06/2010 Measured as counts per minute (cpm) Average background = 11,042 cpm —~ General Direction Down-Slope ~ Mine Claim Boundaries Observed Reclamation Cap Feet 250 ffBmnBQZEi. ------- Figure 2 - Gamma Radiation Measurements Silentman 1 (62) Teec Nos Pos Chapter, Navajo Nation Silentman 1 (62) Legend —~ General Direction Down-Slope Gamma Radiation Measurements Mine Claim Boundaries 0-10,000 10,000- 15,000 15,000-20,000 20,000-50,000 50,000- 100,000 > 100,000 Observed Reclamation Cap Gamma survey conducted 06/2010 Measured as counts per minute (cpm) Average background 11,042 cpm Feet ------- |