ACM Smelter and Refinery EPA ID No.: MTD093291599
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HRS DOCUMENTATION RECORD--REVIEW COVER SHEET Name of Site: ACM Smelter and Refinery EPA ID No.: MTD093291599 Contact Persons Site Investigation: URS Operating Services for EPA (303) 296-3523 1099 18th Street Suite 710 Denver, Colorado 80202 Documentation Record: Gwen Christiansen (303) 312-6463 NPL Coordinator U.S. Environmental Protection Agency, Region 8 1595 Wynkoop Street, Mail Code: 8EPR-B Denver, Colorado 80202 Pathways, Components, or Threats Not Scored Ground Water Migration Pathway Based on lack of analytical data supporting a release to the aquifers and on the fact that the ground water is not used as a drinking water source, the ground water pathway will not be scored as part of this Hazard Ranking System (HRS) package. Air Migration Pathway Documentation of investigations from over 100 years ago conducted by the Boston and Montana Consolidated Copper and Silver Mining Company (Boston & Montana) and later by Anaconda Copper Mining Company (ACM) indicates that the operators of the smelter and refinery were aware that a significant amount of contamination was being emitted by the stack. Topsoil samples were collected and analyzed by the Boston & Montana laboratory in 1904 and 1905. Company chemists concluded that over 40 pounds of arsenic trioxide (As203) had been deposited per acre up to a distance of 6.24 miles to the northeast of the stack (Ref.32, p. 2). Samples collected from different locations in 1905 confirmed the aerial deposition of contaminates from the stack (Ref. 47, p. 2). Internal ACM company correspondence from November 1951 indicated that the amount of arsenic leaving the stack per twenty-four hours in the early 1950s was approximately 15.04 pounds (Ref. 33). The EPA chooses not to score the Air Migration Pathway at this time; however the EPA is interested in this potential pathway and may choose to pursue it further at a later date. HRS Documentation Record ACM Smelter and Refinery March 2010 MTD093291599 HRS DOCUMENTATION RECORD Name of Site: ACM Smelter and Refinery Date Prepared: March 2010 EPA Region: Region 8 Street Address of Site: River Road North, 1 mile East of 15th Street City, County, State: Black Eagle, Cascade County, Montana 59414 *General Location in the State: The ACM Smelter and Refinery and the community of Black Eagle are located on the north bank of the Missouri River, north of Great Falls, Montana (Ref. 3; Ref. 4). Topographic Map: Northwest Great Falls, Montana 1994 and Northeast Great Falls, Montana Latitude: 47°31’ 42.97” North Longitude: 111° 14’ 47.28” West (Ref. 3; Ref. 4) The location of the reference point at the East Ditch Dump near the south boundary of the former smelter facility close to the Missouri River. Scores Ground Water Pathway 0.00 Surface Water Pathway 100.00 Soil Exposure Pathway 78.30 Air Pathway 0.00 HRS SITE SCORE 63.50 *The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area the site is located. They represent one or more locations EPA considers to be part of the site based on the screening information EPA used to evaluate the site for NPL listing. EPA lists national priorities among the known “releases or threatened releases” of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has been “deposited, stored, placed or otherwise come to be located.” Generally, HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to be addressed under CERCLA. Accordingly, EPA contemplates that the preliminary description of facility boundaries at the time of scoring will be refined as more information is developed as to where the contamination has come to be located. HRS Documentation Record ACM Smelter and Refinery March 2010 - 1 - MTD093291599 WORKSHEET FOR COMPUTING HRS SITE SCORE S S2 1. Ground water Migration Pathway Score (Sgw) NS NS (from Table 3-1, line 13) 2a. Surface Water Overland/Flood Migration Component 100 (from Table 4-1, line 30) 2b. Ground water to Surface Water Migration Component NS (from Table 4-25, line 28) 2c. Surface Water Migration Pathway Score (Ssw) 100 10,000.00 Enter the larger of lines 2a and 2b as the pathway score. 3. Soil Exposure Pathway Score (Ss) 78.30 6,130.89 (from Table 5-1, line 22) 4. Air Migration Pathway Score (Sa) (from Table 6-1, line 12) NS NS 2 2 2 2 5. Total of Sgw + Ssw + Ss + Sa 16,130.89 6. HRS Site Score Divide the value on line 5 by 4 and take the square root 63.50 NS = Not Scored HRS Documentation Record ACM Smelter and Refinery March 2010 - 2 - MTD093291599 SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SCORE SHEET Maximum Value Factor Categories and Factors Value Assigned Drinking Water Threat Likelihood of Release: 1. Observed Release 550 550 2. Potential to Release by Overland Flow: 2a. Containment 10 NS 2b. Runoff 25 NS 2c. Distance to Surface Water 25 NS 2d. Potential to Release by Overland Flow (lines 2a[2b+2c]) 500 NS 3. Potential to Release by Flood: 3a. Containment (Flood) 10 NS 3b. Flood Frequency 50 NS 3c. Potential to Release by Flood (lines 3a×b) 500 NS 4. Potential to Release (lines 2d+3c, subject to a maximum of 500) 500 NS 5. Likelihood of Release (higher of lines 1 and 4) 550 550 Waste Characteristics: 6. Toxicity/Persistence (a) NS 7. Hazardous Waste Quantity (a) NS 8. Waste Characteristics 100 NS Targets: 9. Nearest Intake 50 NS 10. Population 10a. Level I Concentrations (b) NS 10b. Level II Concentrations (b) NS 10c. Potential Contamination (b) NS 10d. Population (lines 10a+10b+10c) (b) NS 11. Resources 5 NS 12. Targets (lines 9+10d+11) (b) NS Drinking Water Threat Score: 13. Drinking Water Threat Score ([lines 5×8×12]/82,500, subject to a maximum of 100) 100 NS Human Food Chain Threat Likelihood of Release: 14. Likelihood of Release (same value as line 5) 550 550 Waste Characteristics: 15. Toxicity/Persistence/Bioaccumulation (a) 500,000,000 16. Hazardous Waste Quantity (a) 100 17. Waste Characteristics 1,000 320 HRS Documentation Record ACM Smelter and Refinery March 2010 - 3 - MTD093291599 SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SCORE SHEET Maximum Value Factor Categories and Factors Value Assigned Targets: 18. Food Chain Individual 50 45 19. Population 0 19a. Level I Concentrations (b) 19b. Level II Concentrations (b) 0.03 19c. Potential Human Food Chain Contamination (b) 0.000003 19d. Population (lines 19a+19b+19c) (b) 0.030003 20. Targets (lines 18+19d) (b) 45.030003 Human Food Chain Threat Score: 21. Human Food Chain Threat Score ([lines 14×17×20]/82,500, subject to a maximum of 100) 100 96.06 Environmental Threat Likelihood of Release: 22. Likelihood of Release (same value as line 5) 550 550 Waste Characteristics: 23. Ecosystem Toxicity/Persistence/Bioaccumulation (a) 500,000,000 24. Hazardous Waste Quantity (a) 100 25. Waste Characteristics 1,000 320 Targets: 26. Sensitive Environments 26a. Level I Concentrations (b) 0 26b. Level II Concentrations (b) 25 26c. Potential Contamination (b) 0 26d. Sensitive Environments (lines 26a+26b+26c) (b) 25 27. Targets (value from line 26d) (b) 25 Environmental Threat Score: 28. Environmental Threat Score ( [lines 22×25×27]/82,500, subject to a maximum of 60) 60 53.33 Surface Water Overland/Flood Migration Component Score for a Watershed 29. Watershed Score (lines 13+21+28, subject to a maximum of 100) 100 100 Surface Water Overland/Flood Migration Component Score c 30. Component Score (Sof) (highest score from line 29 for all watersheds evaluated, subject to a maximum of 100) 100 100 NS = Not Scored. (a) = Maximum value applies to waste characteristics category (b) = Maximum value not applicable (c) = Do not round to the nearest integer HRS Documentation Record ACM Smelter and Refinery March 2010 - 4 - MTD093291599 TABLE 5-1 SOIL EXPOSURE PATHWAY SCORE SHEET Factor Categories and Factors Maximum Value Value Assigned RESIDENT POPULATION THREAT Likelihood of Exposure 1. Likelihood of Exposure 550 550 Waste Characteristics 2. Toxicity (a) 10,000 3. Hazardous Waste Quantity (a) 10 4. Waste Characteristics 100 18 Targets 5. Resident Individual 50 50 6. Resident Population 6a. Level I Concentrations (b) 192.8 6b. Level II Concentrations (b) 409.7 6c. Resident Population (b) (lines 6a + 6b) 602.5 7. Workers 15 0 8. Resources 5 0 9. Terrestrial Sensitive Environments (c) 0 10. Targets (b) 652.5 (lines 5 + 6c + 7 + 8 + 9) Resident Population Threat Score 11. Resident Population Threat (lines 1 x 4 x 10) (b) 6,459,750 HRS Documentation Record ACM Smelter and Refinery March 2010 - 5 - MTD093291599 TABLE 5-1 SOIL EXPOSURE PATHWAY SCORE SHEET Factor Categories and Factors Maximum Value Value Assigned NEARBY POPULATION THREAT Likelihood of Exposure 12. Attractiveness/Accessibility 100 NS 13. Area of Contamination 100 NS 14. Likelihood of Exposure 500 NS Waste Characteristics 15. Toxicity (a) NS 16. Hazardous Waste Quantity (a) NS 17. Waste Characteristics 100 NS Targets 18. Nearby Individual 1 NS 19. Population Within 1 Mile (b) NS 20. Targets (lines 18 + 19) Nearby Population Threat Score 21. Nearby Population Threat (lines 14 x 17 x 20) (b) NS SOIL EXPOSURE PATHWAY SCORE Soil Exposure Pathway Scored 22. (Ss), (lines [11 + 21] ÷ 82,500 78.3 subject to a maximum of 100) HRS Documentation Record ACM Smelter and Refinery March 2010 - 6 - MTD093291599 REFERENCES Ref. No. Description of the Reference 1 U.S. Environmental Protection Agency (EPA), Hazard Ranking System; Final Rule, December 14, 1990, 55 FR 51532, Hazard Ranking System (HRS).