HRS DOCUMENTATION RECORD--REVIEW COVER SHEET
 

Name of Site: 

EPA ID No.: 

ACM Smelter and Refinery 

MTD093291599 

Contact Persons 

Site Investigation: URS Operating Services for EPA 

1099 18th Street 

Suite 710 

 Denver, Colorado 80202 

 (303) 296-3523 

Documentation Record: Gwen Christiansen

NPL Coordinator 

 (303) 312-6463 

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 ACM Smelter and Refinery 

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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.
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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 

5. Total of Sgw

2

 + Ssw2 + Ss

2

 + Sa

2

 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 
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SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SCORE SHEET 

Factor Categories and Factors Maximum 

Value 

Value 

Assigned 

Drinking Water Threat 

Likelihood of Release: 

1. Observed Release 

2. Potential to Release by Overland Flow: 

2a. Containment 

2b. Runoff 

2c. Distance to Surface Water 

2d. Potential to Release by Overland Flow (lines 2a[2b+2c]) 

3. Potential to Release by Flood: 

3a. Containment (Flood) 

3b. Flood Frequency 

3c. Potential to Release by Flood (lines 3a×b) 

4. Potential to Release (lines 2d+3c, subject to a maximum of 500) 

5. Likelihood of Release (higher of lines 1 and 4) 

550 

10 

25 

25 

500 

10 

50 

500 

500 

550 

550 

NS 

NS 

NS 

NS 

NS 

NS 

NS 

NS 

550 

Waste Characteristics: 

6. Toxicity/Persistence 

7. Hazardous Waste Quantity 

8. Waste Characteristics 

(a) 

(a) 

100 

NS 

NS 

NS 

Targets:

9. Nearest Intake 

10. Population 

10a. Level I Concentrations 

10b. Level II Concentrations 

10c. Potential Contamination 

10d. Population (lines 10a+10b+10c) 

11. Resources 

12. Targets (lines 9+10d+11) 

50 

(b) 

(b) 

(b) 

(b) 

5 

(b) 

NS 

NS 

NS 

NS 

NS 

NS 

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 

16. Hazardous Waste Quantity 

17. Waste Characteristics 

(a) 

(a) 

1,000 

500,000,000 

100 

320 
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SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SCORE SHEET 

Factor Categories and Factors Maximum 

Value 

Value 

Assigned 

Targets:

18. Food Chain Individual 

19. Population 

19a. Level I Concentrations 

19b. Level II Concentrations 

19c. Potential Human Food Chain Contamination 

19d. Population (lines 19a+19b+19c) 

20. Targets (lines 18+19d) 

50 

(b) 

(b) 

(b) 

(b) 

(b) 

45 

0 

0.03 

0.000003 

0.030003 

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 

24. Hazardous Waste Quantity 

25. Waste Characteristics 

(a) 

(a) 

1,000 

500,000,000 

100 

320 

Targets:

26. Sensitive Environments 

26a. Level I Concentrations 

26b. Level II Concentrations 

26c. Potential Contamination 

26d. Sensitive Environments (lines 26a+26b+26c) 

27. Targets (value from line 26d) 

(b) 

(b) 

(b) 

(b) 

(b) 

0 

25 

0 

25 

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 

30. Component Score (Sof)

c

 (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 

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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 

(lines 6a + 6b) 

(b) 

 602.5 

7. Workers 15 0 

8. Resources 5 0 

9. Terrestrial Sensitive Environments (c) 0 

10. Targets 

(lines 5 + 6c + 7 + 8 + 9) 

(b) 652.5 

Resident Population Threat Score

11. Resident Population Threat 

(lines 1 x 4 x 10) (b) 6,459,750 
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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 

subject to a maximum of 100) 

78.3 
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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). 137 pages. 

2 U.S. Environmental Protection Agency (EPA). Superfund Chemical Data Matrix, Hazardous 

Substance Reference Table. January 2004. Excerpt, 52 pages. 

http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm. 

3 URS Operating Services. 2010. Memorandum to file, from Jeremiah Ervin, URS Operating Services, 

Inc. Subject: Latitude and Longitude of the Former Anaconda Mining Company Refinery East Ditch 

Dump Adjacent to Missouri River in the Community of Black Eagle, Montana and Attached Map. 

January 28, 2010. 2 pages. 

4 U.S. Geological Survey (USGS). 1975. 7.5' Series Topographic Maps. Map 1-Northwest Great 

Falls, Montana (1994) and Map 2-Northeast Great Falls, Montana (1975), 2 Maps. 

5 URS Operating Service, Inc. 2008a. Analytical Results Report for CERCLA Expanded Site 

Investigation. Anaconda Minerals Co, Great Falls Refinery, Great Falls, Montana. December 31, 

2008. 96 pages. Excerpts Appendix A, 53 pages. Excerpts Appendix B, 21 pages. Excerpts 

Appendix C, 173 pages. Excerpts Appendix D, 59 pages. Excerpts Appendix E, 13 pages. 

6 Montana, The Magazine of Western History. 2001. “The Goldfish Died”. By Gorden Morris 

Bakken and J. Elwood Bakken. Winter 2001. Volume 51, Number 4. Pages: table of contents, 38-46 

and 49-51. 

7 Great Falls Tribune. 2002. “A Brief History of the Smelter Hill.” Research done by Cascade 

County Attorney’s Office. February 22, 2002. page 5A. 

8 Great Falls Tribune. 2002. “The Rise and Fall of the World’s Tallest Smokestack”. By Také Uda 

and Paula Wilmot. September 18, 2002. pages 6A-7A. 

9 Great Falls Tribune. 1982. “The Big Stack”. Monument of Strength by Tom Kerin. 56 pages. 

Excerpt pages: cover page, table of contents, 15 and 20. 

10 Montana Bureau of Mines and Geology. 2002. Geologic Map of the Great Falls North 30’ x 60” 

Quadrangle, Central Montana. Compiled by Susan M. Vuke, Roger B. Golton, and David S. 

Fullerton. Open File Report No. 459. 1 map. 

11 Reference Reserved. 

12 Reference Reserved. 

13 U.S. Geological Survey, National Water Information System: Web Interface. Water Data Report for 

2008. USGS 06090300 Missouri River near Great Falls, Montana. Website accessed on July 6, 

2009. http://wdr.water.usgs.gov/wy2008/pdfs/06090300.2008.pdf. 3 pages. 

14 Letter to E. P. Mathewson from Manager of Boston and Montana Smelter. April 20, 1907. 1 page. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 8 - MTD093291599 

15 Letter to C. W. Goodale from Boston and Montana Legal Department. February 6, 1909. Three 

pages. 

16. Montana Department of Environmental Quality, Remediation Division. 2002. Site Inspection 

Report. May 28, 2002. 31 pages. 

17 Letter to J.H. Klepinger from Milo W. Krejer. 1914. Subject Slime Samples Takes Above Rainbow 

Falls Dam. September 5, 1914. 1 page. 

18 Tetra Tech EM Inc. 2004. Final Analytical Results Report for Expanded Site Inspection, Anaconda 

Minerals Company, Great Falls Refinery, Black Eagle, Cascade County, Montana. June 2004. 208 

pages. 

19 Final Report: Chemical Concentrations in Sediment, Surface Water, and Fish Tissue from the Great 

Falls Historical Metals Smelter/Refinery Site – Winter 2004. 2005. Parametrix. 53 pages 

20 U.S. Environmental Protection Agency. 2005. Memorandum from Dale J. Hoff, Ph.D., Regional 

Ecotoxicologist to Jim Harris, Site Assessment Manager, Great Falls Smelter Site, Great Falls, Mt. 

Subject: Review of Draft Report: Chemical Concentrations in Sediment, Surface Water, and Fish 

Tissue from the Great Falls Historical Metals Smelter/Refinery Site-Winter 2004. Parametrix, May 

2005. June 8, 2005. 2 pages. 

21 URS Operating Services, Inc. 2007. Analytical Results Report for CERCLA Site Assessment. 

Anaconda Minerals Co, Great Falls Refinery, Great Falls, Montana. Pages: cover page and i-iv, 1-33. 

 Appendix C-Project Photolog, 59 pages, Appendix D-Property Sketch Forms, 64 pages. 

22 URS Operating Services. 2010. Memorandum and Figure. Subject: Combined Area of Arsenic and 

 Cadmium Contamination Determined by Analytical Data and Geographical Information System (GIS) 

 Spatial Data. Figure B. January 25, 2010. 2 pages. 

23 URS Operating Service, Inc. 2009c. Analytical Results Report for CERCLA Site Assessment 

Expanded Site Investigation of the Missouri River Sediments. Anaconda Minerals Co, Great Falls 

Refinery, Great Falls, Cascade County, Montana. August 31, 2009. 205 pages. 

24 URS Operating Services, Inc. 2009d. Memorandum to File from Jeremiah Ervin. September 01, 

2009. Subject: Determination of Areas of contamination by analytical data and Geographical 

Information System (GIS) Spatial Data with attached GPS sample location coordinates. 12 pages. 

25 URS Operating Services, Inc. 2009e. Memorandum to File from Barry Hayhurst. January 26, 2010. 

 Subject: Calculation of square footage of combined arsenic and cadmium contaminated soil covered 

by paved streets in the unincorporated community of Black Eagle, Montana using sample data 

collected in August 2007 and July 2008. 1 page. 

26 URS Operating Services, Inc. 2009f. Memorandum to File from Barry Hayhurst. August 04, 2009. 

Subject: Calculation of structure and pavement coverage of lots sampled in Black Eagle, Montana in 

July 2008. 3 pages. 

27 Tech Law, Inc. 2008. Data Validation Reports for Anaconda Minerals Co. Great Falls Refinery. 

Reports nos. MH21S2, MH26P1, and MH26N3. December 03, 2008. 110 pages. 

28 U.S. Census Bureau. 2009. Cascade County, Montana – QuickFacts from the U.S. Census Bureau. 

http://quickfacts.census.gov/qfd/states/30/30013.html. Accessed August 12, 2009. 1 Page. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 9 - MTD093291599 

29 Great Falls Tribune. 2002. “Mountains of Slag Dumped into Missouri” by Sonja Lee Sunday, 

September 22, 2002. Page 8A. 

30 National Oceanic and Atmospheric Administration (NOAA). 2007. Email from Edward Kurdy of 

NOAA to Barry Hayhurst of URS Operating Services with attachments of monthly wind roses from 

great falls international airport. 13 pages. 

31 Amelia H. Kleinschmidt. 1919. Letter to Amalgamated Copper Company. February 4, 1919. 1 

page. 

32 Goodale, C. W. 1904. Letter to A. K. Wheeler, Superintendent Great Falls, Montana from C. W. 

Goodale, Assistant Manager. Re: Samples of Grass and Topsoil collected April 11, 1904. May 7, 

1904. 2 pages. 

33 Anaconda Copper Mining Company, Great Falls Reduction Department. 1951. Memorandum to file 

from Assistant Superintendent, Zinc. Roasters. November 16, 1951. 1 page. 

34 Montana Department of Fish, Wildlife, and Parks. 2009. Fax from Bill Gardner of Montana 

Department of Fish, Wildlife & Parks to Barry Hayhurst, URS Operating Services, Inc., regarding 

Black Eagle Fisheries on the Missouri River. 2 pages. 

35 U.S. Fish and Wildlife Service (USFWS). 1999. National Wetlands Inventory Maps of the 7.5 

Minute Topographic Map Quadrangles, Northwest Great Falls, Montana and Northeast Great Falls, 

Montana. 2 sheets. Annotated Excerpt of Northwest Great Falls Montana Sheet. 1 page. 

36 URS Operating Services. 2008b. Three field Logbooks for the Anaconda Minerals Co, Great Falls 

Refinery ESI. Logbook No. 1, 8 pages; Logbook No. 2, 19 pages; Logbook No. 3, 25 pages. 

37 Plat Map for Black Eagle, Montana. 2004. http://nris.mt.gov/nsdi/orthophotos. 

38 Reference Reserved. 

39 Reference Reserved. 

40 Montana Fish, Wildlife, and Parks. 2009. Giant Springs State Park. Website 

http://fwp.mt.gov/lands/site_282690.aspx. Accessed August 16, 2009. 4 pages. 

41 River’s Edge Trail Map. 2009. Rivers Edge Trail Recreational Trails Map. 1 sheet. Website 

http://www.thetrail.org/TrailMaps/RET-09URBAN-HiRes.pdf. Accessed Sept 14, 2009. 

42 URS Operating Services, Inc. 2010. Figure E, AMC Smelter and Refinery Area map. 1 page. 

43 EPA. 1996. Using Qualified Data to Document an Observed Release and Observed Contamination. 

 18 pages. 

44 URS Operating Services, Inc. 2009g. Memorandum to File from Barry Hayhurst. Subject: Fishing 

on the Missouri River between Black Eagle and Rainbow Dams. September 25, 2009. 1 page. 

45 URS Operating Services, Inc. 2009h. Memorandum to File from Barry Hayhurst. Subject: Fishing 

on the Missouri River Between Black Eagle and Rainbow Dams and the consumption of the fish 

caught in this section of the Missouri River. October 01, 2009. 1 page. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 10 - MTD093291599 

46 URS Operating Services, Inc. 2009i. Memorandum to File from Barry Hayhurst. Subject: 

Consumption of fish caught from the Missouri River. October 14, 2009. 1 page. 

47 Boston Montana Consolidated Copper and Silver Mining Company, Great Falls, Montana. 1905. 

Letter from K. E. Wheeler, Superintendent to C. W. Goodall, Manager with attached assay certificate 

for soil samples collected March 29, 1905. 2 pages. 

48 U.S. Environmental Protection Agency. 1995. Establishing Background Levels. Directive 9286.7-

19FS. September 1995. 7 pages. 

49 URS Operating Services, Inc. 2010. Figure A: 2007 /2008 Background Sample Locations Map. 

January 2010. 1 sheet. 

50 URS Operating Services, Inc. 2009k. Figure C: Site Details and Sample Location Map with 15-

Mile Downstream TDL. 1 sheet. 

51 TLI Solutions. 2007. Data Validation Reports for 2007 soil data: SDG MH1H13, MH1H19, 

MH1H34, AND MH1H43. December 07, 2007. 160 pages. 

52 URS Operating Services. 2007. Field Logbook of Barry Hayhurst, July 15-August 13, 2007. 38 

pages. 

53 URS Operating Services, Inc. 2009l. Memorandum to File. Bryan Williams, URS Op. Services. 

Source 2 Information. December 01, 2009. 1 page. 

54 URS Operating Services, Inc. 2009m. Memorandum to File. Bryan Williams, URS Op. Services. 

Sample comparability. December 01, 2009. 1 page. 

55 Cascade County Public Works Department. 2009. Email from Jim Young, P.E.-Senior Civil 

Engineer with attachment showing outfalls from Black Eagle to the Missouri River. December 18, 

2009. 19 pages. 

56 History of Great Falls, Montana. 2009. http://100megsfree3.com/mickme/1800.html. December 28, 

2009. 4 pages. 

57 Office of Surface Mining Reclamation and Enforcement. Annual Evaluation Summary Report for the 

Mine Waste Cleanup Bureau’s Abandoned Mine Lands Program for the State of Montana. 

Evaluation Year 2004 (July 1, 2003-June 30, 2004). 17 pages. 

58 ARCO Environmental Remediation, L.L.C. and Cascade Count and the City of Great Falls, Montana. 

 2000. Montana Voluntary Cleanup and Redevelopment Act (VCRA) Application, Former Great 

Falls Refinery Site, Great Falls Montana. June 26, 2000. 350 pages plus 1 map, Appendix I. 

59 Cascade County Public Works Department. 2010. Email from Jim Young, P.E.-Senior Civil 

Engineer to Barry Hayhurst, URS Corp. with attachment showing boundaries of outfalls from Black 

Eagle to the Missouri River. January 4, 2010. 2 pages. 

60 A4 Scientific, Inc. 2007a. CLP data package for Sample Delivery Group (SDG) SDG MH1H19. 622 

pages. 

61 A4 Scientific, Inc. 2007b. CLP data packages for Sample Delivery Group (SDG) MH1H34. 590 

pages. 
 

62 A4 Scientific, Inc. 2007c. CLP data packages for Sample Delivery Group (SDG) MH1H43. 591 

pages. 

63 Chemtech Consulting Group. 2008a. CLP Data Package for Sample Delivery Group (SDG) 

MH26N3. 296 pages. 

64	 Chemtech Consulting Group. 2008b. CLP Data Package for Sample Delivery Group (SDG) 

MH26P1. 190 pages. 

65 Montana Refining Company. January 28, 2010. Website: http://montanarefining.com. 1 page. 

66 U.S. Energy Information Administration. January 28, 2010. Ranking of U.S. Refineries. Website: 

http://www.eia.doe.gov/neic/rankings/refineries.htm. 5 pages. 

67 Compuchem Laboratories. 2010. Email from Cathy Dover, Supervisor of Project Management, 

Compuchem to Kim Ohlson, URS Corp. Subject: Metals WO#0907118 Revised Form 10. February 

3, 2010. 3 pages. 

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HRS Documentation Record ACM Smelter and Refinery 

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SITE HISTORY and DESCRIPTION 

The ACM Smelter and Refinery site is located in Black Eagle, Montana, near the city of Great Falls (Ref. 3; 

Ref. 4). As will be described below and in the following pages, the site consists of sources and releases 

related from the Anaconda Copper Mining Company (ACM) smelter and refining operations (also known as 

the Anaconda Minerals Co. (AMC), Great Falls Refinery facility). Releases from these operations affect the 

residential community of Black Eagle and the fisheries and sensitive environments associated with the 

Missouri River as will be described in this HRS documentation record. 

Great Falls, Montana was founded by Minneapolis entrepreneur, Paris Gibson, in 1883 with the vision of a 

metropolis based upon the waterpower of the Missouri River (Ref. 6, p. 40). In 1889 the Boston and Montana 

Consolidated Copper and Silver Mining Company (Boston & Montana), headquartered in nearby Butte, 

Montana, decided to build a new smelter on the north bank of the Missouri River at Great Falls, Montana. 

The new smelter would use nearby coal deposits for smelting and the hydro power of the Missouri River to 

mechanically treat ore, to sluice away byproducts, and to generate electricity for electrolytic refining. The 

new Boston & Montana Refinery opened in 1893 and soon employed 1,200 men (Ref. 6, p. 41). Most of the 

ore processed at the new smelter came from the mines in Butte, Montana (Ref. 7, p. 5A; Ref. 6 p. 41). 

The consolidation of the five major Montana copper operations under the Anaconda Copper Mining Company 

in 1910 resulted in the Great Falls operation specializing in the refining process and as a result in 1916 new 

electrolytic copper and zinc operations were built at the Anaconda Minerals Co, Great Falls Refinery facility 

(Ref. 9, p. 20). A new mill was constructed on the site in 1918 to produce copper wire, rod, and cable (Ref. 7, 

p. 5A). By mid-century the ACM facility had taken on the appearance that is depicted in the annotated 

photograph published in the Great Falls Tribune’s story “The Rise and Fall of the world’s tallest smokestack” 

(Ref. 8, p. 6A). 

The smoke stack at the original 1893 plant was 186 feet tall (Ref. 8, p. 6A). The Big Stack was constructed in 

1908 to a length of 506 feet and a total height of 751 feet above the smelter’s blast furnace (Ref. 8 p. 7A). 

The Big Stack went into service on June 12, 1909 and continued belching smoke until August 06, 1972 (Ref. 

9, p. 15). The Big Stack was designed to eject a volume of 1,575,000 cubic feet of air per minute at a velocity 

of 450 feet per minute, a sufficient volume and rate to entrain and remove from the smelter all the gases and 

dust generated during the smelting process (Ref. 9, p. 20). 

The wind in the Great Falls Montana area primarily blows from the southwest to the east-northeast, 

particularly in the months of October through March. Wind data collected at the Great Falls International 

Airport, approximately 5 miles southwest of the community of Black Eagle show that during March, April, 

and May the winds can blow from the northwest or northeast more than twenty percent of the time and that in 

the summer months of June, July, and August wind direction over Black Eagle is from the northeast or east 

more than 20 percent of the time (Ref. 30, pp. 2-13). A historic south facing aerial photo published by the 

Great Falls Tribune in 2002 shows smoke from the 506 foot tall stack wafting westward across the 

community of Black Eagle with the city of Great Falls shown in the background beyond the Missouri River 

(Ref. 29, p. 8A). Area ranchers began complaining about contamination from the smelter and refinery stack 

falling on their property and adversely affecting their livelihood in the early 1900s (Ref. 31). Chemical 

assays of flue dust and top soil near the stack performed by Boston & Montana chemists in 1904 and 1905 

concluded that over 40 pounds of arsenic trioxide (As203) had been deposited per acre by March of 1904 at a 

distance 6.24 miles from the stack (Ref. 32, p. 2). Additional sampling at new locations performed in 1905 

concluded that almost 14 pounds of arsenic trioxide (As203) had been deposited at 2.5 miles from the stack 

(Ref. 47, p. 2). An internal Anaconda Copper Mining Company Memorandum from 1951 stated that 

approximately 15.04 pounds of arsenic passed out of the stack every 24 hours (Ref. 33, p. 1). For these 

reasons, aerial deposition of contaminants emanating from the smelter smoke stacks between 1893 and 1972 

is the most likely mechanism of contaminant transport to the residential soils in the community of Black 

Eagle. 
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The Boston and Montana smelter routinely dumped large quantities of granulated slag and tailings into the 

Missouri River (Ref. 6, p. 42; Ref. 15, p. 1). In 1907, the Boston and Montana Consolidated Copper and 

Silver Mining Company estimated that the facility could receive up to 4800 tons a day of ore and changing 

the disposal of slag to railcar would significantly increase rail traffic (Ref. 14, p. 1). The Montana Department 

of Environmental Quality (Montana DEQ) estimates that between 27,500,000 and 31,000,000 cubic yards of 

waste were dumped into the Missouri River between 1893 and 1915 until onsite containment was instituted in 

1915. Montana DEQ also reports that it is possible that dumping of waste into the Missouri River continued 

at a reduced rate after 1915 until the facility closed in the 1970s (Ref. 16, p. 1). So much smelter waste was 

dumped into the Missouri River between 1893 and 1915 that the management and legal department of the 

Boston and Montana Company were concerned that the Federal Government would intervene and enjoin the 

deposition of tailings into the Missouri River by virtue of the constitutional provisions requiring the federal 

government to maintain navigable streams (Ref. 15, pp. 1 and 2). In 1884 Judge Lorenzo Sawyer of the 

United States Circuit Court in San Francisco had granted a perpetual injunction against hydraulic mining in 

California’s American River on these very grounds (Ref. 6, p. 38). 

Numerous complaints were filed by property owners and communities along the Missouri River downstream 

of the ACM Smelter and Refinery of water quality issues and slag and smelter waste clogging the Missouri 

River (Ref. 6, p. 42; Ref. 29, p. 8A). These complaints increased after the 1908 flood of the Missouri River 

inundated the community of Fort Benton, 40 miles downstream of the Boston and Montana Smelter with 

smelter waste (Ref. 6, p. 38; Ref. 29, p. 8A). A company analysis of slime (very fine grained slag and 

tailings, which tended to float in the Missouri River) taken above Rainbow Falls Dam in 1914 indicated that 

the slime contained between .55 and 1.1 percent copper (Ref. 17, p. 1). The Boston and Montana Company 

sought to buy off disgruntled property owners and placate communities by providing alternate domestic water 

sources (Ref. 6, pp. 49-51). 

The Montana DEQ collected the first samples of Missouri River sediment for environmental analysis in May 

of 2002. These samples were collected from the Fort Benton area, approximately 30 miles downstream from 

the ACM Smelter and Refinery. The Montana DEQ concluded that the five samples that had been collected 

contained anomalously high levels of antimony, arsenic, copper, lead, zinc, and other metals and 

recommended that additional samples be taken from the smelter site in Black Eagle down to Judith Landing 

(State Highway 287) (Ref. 16, p. 2). 

The EPA conducted an Expanded Site Inspection of the ACM Smelter and Refinery facility in April 2003 that 

included source samples and nine sediment samples from the Missouri River (Ref. 18, p. 8). Elevated 

concentrations of arsenic, cadmium, copper, lead, manganese, mercury, silver and zinc were detected in most 

of the samples as compared to background (Ref. 18, pp. 23-24). 

The current owner, Atlantic Richfield Company, conducted a limited study of sediment, surface water and 

fish tissue from the Missouri River near the facility in November, 2004 (Ref. 19, p.7). Their conclusions of 

the investigation were that concentrations of metals adjacent to and downstream of the ACM Smelter and 

Refinery facility were comparable to or even less than background concentrations of the metals (Ref. 19, p. 

8). A review of the report by the EPA’s Regional Ecological toxicologist noted that at three sample locations 

ecotoxicological benchmarks were exceeded in soil samples, and it is likely that higher concentrations of 

metals in all samples could have been obtained by taking samples on the north side of the Missouri River, 

which is the same side as the facility rather than across the River on the south bank of the Missouri River 

(Ref. 20, pp.1, 2). 

The EPA conducted a Site Assessment of the residential soil in Great Falls, Montana south of the site of the 

former refinery and smelter and in the community of Black Eagle, Montana in 2007. Between the dates of 

August 8 and 15, 2007, samples were collected from sixty-three residential properties. The 2007 

investigation identified a large area of elevated concentrations of arsenic, cadmium, and lead in the 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 14 - MTD093291599 

community Black Eagle and one property in Great Falls contained an elevated concentration (Ref. 21, p.18; 

Ref. 22, pp. 1-2). 

The EPA conducted an Expanded Site Inspection of the residential soils in the community of Black Eagle, 

Montana in 2008 utilizing the same sample collection and analytical procedures as the 2007 investigation 

(Ref. 21, pp. 11-12; Ref. 5, p. 11). Between the dates of July 8 and 16, 2008 samples were collected from 

fifty-nine residential properties (Ref. 5, p. 1). The 2008 investigation also identified a large area of elevated 

arsenic and lead concentrations in residential soil as compared to background in an area centered on the 

central and southwestern area of the community of Black Eagle (Ref. 5, p. 13; Ref. 22 pp. 1-2). 

The EPA conducted an Expanded Site Inspection of the sediments in the Missouri River adjacent to and 

downstream of the ACM Smelter and Refinery property in July 2009. On July 14, eight sediment samples 

were collected from along the north side of the Missouri River channel between the 11th Street Bridge and 

Rainbow Dam (Ref. 23, pp. 15 and 21). This investigation identified a stream segment of 2.39 miles with 

concentrations of copper, lead, and silver (Ref. 23, p. 21). This segment of the Missouri River includes 

widely used fishing areas (Ref. 34, p. 2). Fishing was observed by the sampling team during the 2009 

Expanded Site Inspection (Ref. 23, p. 14, 23, 28, and 33). The Montana Department of Fish, Wildlife and 

Parks estimates that a population of 1,292 rainbow trout and 302 brown trout are found in the 1.5 mile stretch 

between Black Eagle Dam and Giant Springs State hatchery based on an electroshock survey done before 

stocking in the summer of 2000 (Ref. 34, p. 1). The fish that are caught along this stretch of the river are 

eaten by the anglers and their families (Ref. 44; Ref. 45; and Ref. 46). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 15 - MTD093291599 

2.2.1 SOURCE IDENTIFICATION 

Name of the Source: Black Eagle Residential Soil

Number of Source: 1

Source Type: contaminated soil

Description and Location of the source: 

Residential soil contamination in the unincorporated residential community of Black Eagle located on the 

north bank of the Missouri River across from Great Falls, Montana, was first documented by the EPA’s 2003 

Expanded Site Inspection when elevated concentrations of antimony, arsenic, cadmium, chromium, cobalt, 

copper, iron, lead, manganese, mercury, nickel, silver, sodium, and zinc were found in one or more samples 

(Ref. 4, map 1; Ref. 18, pp. 28-30). 

The 2007 EPA CERCLA Site Assessment sampled residences on both the north and south sides of the 

Missouri River adjacent to the Anaconda Minerals Co, Great Falls Refinery (Ref. 21, p. 11). Of the eleven 

residences sampled in Great Falls on the south side of the Missouri River in August of 2007 only one 

residence had an elevated concentration of arsenic (Ref. 21, p. 13). The results of the 2007 investigation of 

the residential soil in the community of Black Eagle identified an area of arsenic, cadmium, and lead 

concentrations greater than three times background centered on eastern and central Black Eagle (Ref. 21, p. 

13-14, 18). 

The 2008 EPA CERCLA Expanded Site Investigation was focused in the unincorporated community of Black 

Eagle, Montana. The residential soil at fifty nine residential properties in Black Eagle was sampled in July 

2008 to a depth of one foot (Ref. 5, p. 1). Concentrations of arsenic, cadmium, and lead elevated three times 

background were detected in the residential soil in Black Eagle centered on the central and southwestern area 

of Black Eagle (Ref. 5, p. 13; Ref. 22, pp. 1-2). 

The regional setting of the community of Black Eagle, the Missouri River, Great Falls, and the ACM Smelter 

and Refinery are shown in Figure E (Ref. 42, 1 page). For this document the combined area of arsenic and 

cadmium contamination (not corrected for covered soil) greater than three times background and above a 

health based benchmark was used to define the source. Samples from the 0-2 inch horizon were compared to 

background samples from the 0-2 inch horizon, and samples from the 6-12 inch horizon were compared to the 

background samples from the 6-12 inch horizon. There are eight sample locations with arsenic or cadmium 

concentrations greater than times background and are above a health based benchmark. There are an 

additional forty-five locations where cadmium and/or lead concentrations are simply greater than three times 

background (see Section 2.2.1.2 of this HRS documentation record). Lead contamination was not used to 

calculate the area of contaminated soil, but elevated lead concentrations are presented to show that a pattern of 

contamination is pervasive throughout the area delineated by the arsenic and cadmium results. The area of 

soil delineated by the 2007 and 2008 investigation results for residential soil contaminated by arsenic and 

cadmium is 1,926,569 square feet (Ref. 22, pp.1- 2). Areas were calculated using Global Positioning System 

(GPS) coordinates of the sample locations and processed with geographic information system (GIS) software 

(Ref. 24, p. 1). 

The background samples used to calculate the values to determine the residential soil source area are 

presented in the table below. Two locations were sampled in 2007 from the 0-2 inch and 6-12 inch horizon 

and two locations were sampled from the 0-2 inch horizon in 2008 (Ref. 5, p. 10; Ref. 21, p. 11; Ref. 36, book 

2, p. 3 & book 3, pp. 17-18; Ref. 52, pp. 15-16, 28; Ref. 49, 1 page). The highest background sample result 

for each of the horizons was selected as the background sample for that horizon. All background values 

selected were obtained from 2007 background samples with four of the six background values derived from 

the background samples collected from North Middle School (R08ST2601F102 and R08ST2601F112), which 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 16 - MTD093291599 

was also the location of the 2004 soil background sample (Ref. 18, p. 27). All samples were collected as grab 

samples following the guidelines of the UOS TSOPs using stainless steel spoons, bowls, and hand augers to 

collect the soil into 12X12 inch seal top poly bags. The 0-2 inch horizon was collected directly into the 

plastic zip lock bag using a stainless steel spoon, and the 6-12 inch horizon was collected using a hand auger 

into a stainless steel bowl where the soil was lightly homogenized by stirring before a sample was collected 

into 12X12 inch seal top poly bags (Ref. 5, p. 11; Ref. 21, pp. 11-12). All of the background samples were 

collected from the area north of the Missouri River, west of the site, in soils developed on the Kootenai 

Formation which also underlies the community of Black Eagle (Ref. 5, p. 5; Ref. 10. 1 sheet; Ref. 21, p. 4). 

The soil was moist, fine-grained well sorted silty sand at the locations (Ref. 52, pp. 15-16 & 28). All soil 

samples collected were analyzed in the field using an x-ray fluorescence (XRF) unit (Ref. 5, p. 12; Ref. 21, p. 

12). All samples for fixed laboratory analyses were analyzed through the EPA’s Contract Laboratory 

Program (CLP), Routine Analytical Services (RAS). The samples collected in 2007 were analyzed by A4 

Scientific, Inc. of The Woodlands, Texas by EPA CLP method ILM05.4 (Ref. 60, p. 1; Ref. 61, p. 1; Ref. 62, 

p. 1). The samples collected in 2008 were analyzed by Chemtech Consulting Group, Mountainside, New 

Jersey by EPA CLP method ILM05.4 (Ref. 63. p. 1; Ref. 64, p. 1). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 17 - MTD093291599 

*ACM Smelter and Refinery – Background Samples 0-2 inch horizon collected in 2007 and 2008 (mg/kg)

Analyte CRDL/ 

MDL(2007/2008) 

SCDM 

Benchmark 

CRSC/ 

RDSC 

Jaycee Park 

R04ST2400F102 

CLP - MHIH26 

Sampled 

8/10/2007 

North Middle 

School 

R08ST2601F102 

CLP - MH1H34 

Sampled 

8/8/2007 

724 25th Ave. 

R25AV0724FY02 

CLP - MH26P6 

Sampled 

7/11/2008 

737 25th Ave. 

R25AV0737SY02 

CLP - MH26P7 

Sampled 

7/11/2008 

Arsenic 1/(0.49/0.37) 0.43 13.3 (10.4 J) 18.1 6.3 16.1 

Cadmium 0.5/(0.20/0.040) 39 1.2 J+ 0.82 J+ 0.53 (0.34 J) 0.48 

Lead 1/(0.49/0.25) - 30.1 (17.5 J) 25.2 25.3 20.6 

Reference Ref. 64, p. 51; 

Ref. 60, p. 64; 

Ref. 61, p. 64; 

Ref. 2, pp. 

BII-13, 

BII-14, 

BII-20 

Ref. 21, p. 29; 

Ref. 51, pp. 

117, 120, 124, 

138; 

Ref. 52. p. 28; 

Ref. 60, pp. 1, 

3, 6, 8, 18, 78, 

363-365, 594, 

599, 604; 

Ref. 21, p. 29; 

Ref. 51, pp. 2, 

5, 9, 16; Ref. 

52, pp. 15-16; 

Ref. 61, pp. 1, 

3, 8, 9, 13, 

219-221, 560, 

566, 570, 

Ref. 5, pp. 28-

31, Appendix C, 

p. 56. Ref. 24, p. 

3, 

Ref. 27, pp. 2, 

3B, 3C, 3F, 3G, 

3H, 9; Ref. 36, 

book 2, p. 3 & 

book 3, pp. 17-

18; Ref. 64. pp. 

1, 4, 7, 9, 15, 79. 

Ref. 5, p. 28, & 

Appendix C, p. 

56. Ref. 24, p. 

3. Ref. 27, pp. 

2, 3B, 3C, 3G, 

3H, 10; Ref. 

36, Book 2, p. 

3; Ref 64, pp. 

1, 4, 7, 9, 16, 80. 

* Sample IDs ending in 02 represent samples collected from 0-2 inches (Ref. 5, p. 10; Ref. 21, p. 11). 

Bold Indicates background value selected for this document / mg/kg 

CRSC Cancer Risk Screening Concentration 

RDSC Reference Dose Screening Concentration 

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram 

**ACM Smelter and Refinery – Background Samples 6-12 inch horizon collected in 2007 (mg/kg)

Analyte CRDL/MDL SCDM 

Benchmark 

CRSC/RDSC 

Jaycee Park 

R04ST2400F112 

CLP - MHIH27 

Sampled 

8/10/2007 

North Middle 

School 

R08ST2601F112 

CLP - MH1H35 

Sampled 8/8/2007 

724 25th Ave. 

6-12 inch sample 

not collected in 

2008 

737 25th Ave. 

6-12 inch sample 

not collected in 

2008 

Arsenic 1/0.49 0.43 17.2 (13.3 J) 23.1 - - 

Cadmium 0.5/0.20 39 0.43 J+ 0.67 J+ - - 

Lead 1/0.49 - 10.6 (12.9 J)18.6 - - 

Reference Ref. 60, p. 64; 

Ref. 61, p. 64; 

Ref. 2, pp. 

BII-13, 

BII-14, 

BII-20 

Ref. 21, pp. 

29-32; Ref. 51, 

pp. 117, 120, 

124, 139; Ref. 

52. p. 28; 

Ref. 60, pp. 1, 

3, 5, 6, 8, 19, 

117, 120, 124, 

139, 366-368. 

Ref. 21, pp.29-

32; Ref. 51, pp. 

2, 5, 9, 17; Ref. 

52, pp. 15-16; 

Ref. 61, pp. 1, 

3, 5, 8, 9, 14, 

222-224 

- - 

** Sample IDs ending in 12 represent samples collected from 6-12 inches (Ref. 5, p. 10; Ref. 21, p. 11). 

Bold Indicates background value selected for this document / mg/kg 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 18 - MTD093291599 

CRSC Cancer Risk Screening Concentration 

RDSC Reference Dose Screening Concentration 

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram
HRS Documentation Record 

March 2010 - 19 - 2.2.1.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCEThe following table lists all detections of arsenic, cadmium, and lead from the 2007 and 2008 EPA investigations of the residenti

which meet the HRS definition of greater than three times background (Ref. 1, Table 2-3, p. 51589). 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

R11ST0111FY02 MH26N3 

111 11th Street 07/11/2008 73.2 3 261 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p. 1; Rp. 5; RefRef. 63, 

R12ST0106FY12 MH26N4 

106 12th Street 07/11/2008 30.6 2.7 98.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p.5; R27, 31, 3Ref. 63, 

R12ST0121FY112 MH26N5 

121 12th Street 07/11/2008 215 13 706 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 23, p. 17; 62, 283. 

R13ST0112BY02 MH26N6 

112 13th Street 07/10/2008 47.3 44.9 562 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 23, p. 12; 62, 283. 

R13ST0117FY02 MH26N7 

117 13th Street 07/11/2008 21.4 69.1 439 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.10; 27, 31, 3
HRS Documentation Record 

March 2010 - 20 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

7; Ref. 143, 283

R13ST0121F112 MH1H38 

121 13th Street 08/11/2007 (66.8 J) 

38.4

(2.5 J+) 

1.8 

(754 J) 

523.6 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi9, 10, 129, 17, 64

R13ST0123FY02 MH26N9 

123 13th Street 07/12/2008 16.5 9.2 432 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.14; 31, 32, 463, pp. 1

R13ST0127FY12 MH26P0 

127 13th Street 07/12/2008 36.3 7.8 340 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.15; 31, 32, 463, pp. 1

R14ST0122F102 MH1H39 

122 14th Street 08/11/2007 (24.2 J) 

13.9 

111 (607 J) 

421.5 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi10, 12, 21, 3, 5, 8

R16ST0121BY12 MH26P1 

121 16th Street 07/14/2008 67.8 14.5 333 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.17; 3B, 3G, Ref. 61, 182, 184

R15ST0215B102 MH1H40 

215 15th Street 08/08/2007 (18 J) 

10.3 

11.6 (553 J) 

384.0 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi
HRS Documentation Record 

March 2010 - 21 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

10, 12, 219, 64, 2

R15ST0307F112 MH1H41 

307 15th Street 08/08/2007 (39.8 J) 

22.9 

(2.2 J +) 

1.6 

(789 J) 

547.9 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi9, 10, 129, 20, 64

R16ST0128F112 MH1H43 

128 16th Street 08/11/2007 (34.5 J) 

19.8 

(2.3 J+) 

1.6 

163 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi52, 53, 513, 64, 1

R17ST0122F112 MH1H44 

122 17th Street 08/11/2007 (60.1 J) 

34.5

(27 J) 

19.2 

967 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi54, 56, 664, 115-

R17ST0125F112 MH1H45 

125 17th Street 08/12/2007 (43.5 J) 

25 

(6.9 J) 

4.9 

162 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi54, 56, 664, 118-

R20ST0118BY12 MH26P3 

118 20th Street 07/10/2008 22.8 9.4 319 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.22; 3B, 3F, 314; Ref. 180, 182 

R21ST0328FY12 MH26P4 

328 21st Street 07/15/2008 72.4 2.5 86.2 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.25; 
HRS Documentation Record 

March 2010 - 22 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

3C, 3F, 318; Ref. 180, 182

R21ST0520FY12 MH26P5 

520 21st Street 07/15/2008 47.5 2.6 90.1 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.30; 3B, 3C, 2, p. 19; 78, 92. 

R21ST0625F112 MH1H47 

625 21st Street 08/10/2007 43.6 2.7 124 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 125Ref. 60, 458. 

R21ST0641S112 MH1H48 

641 21st Street 08/10/2007 38.4 2.8 199 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 1256, 10, 28

R22ST0114B112 MH1H50 

114 22nd Street 08/09/2007 84.4 27.3 397 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 12510, 30, 6

R22ST0118F102 MH1H52 

118 22nd Street 08/09/2007 (22.4 J) 

12.9 

25.8 (519 J) 

399.2 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1210, 23, 6

R22ST0613B112 613 22nd Street 08/10/2007 (39.8 J) 7.8 (272 J) As = 1/0.49/0.43 Ref. 2, 
HRS Documentation Record 

March 2010 - 23 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

MH1H54 22.9 209.2 Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 21, Appendi8, 10, 12pp. 1, 3420-422 

R22ST0633B112 MH1H55 

633 22nd Street 08/10/2007 (53.1 J) 

33.2

2.9 (290 J) 

223.1 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1211, 26, 6

R22ST0641B112 MH2174 

641 22nd Street 08/09/2007 (88.8 J) 

55.5 

3.6 (223 J) 

171.5 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1211, 27, 6

RCHAV1820BY12 MH26Q0 

1820 Chicago Ave. 

07/13/2008 50.9 2.7 89.4 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, p23-24, App. 2, 3B64, pp. 185, 189

RCOAV1508S112 MH2176 

1508 Colorado Avenue 

08/10/2007 (53.1 J) 

33.2

(3 J+) 

2.1 

179 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 53, 8, 10, 

RCOAV1702BY12 MH26Q2 

1702 Colorado Avenue 

07/12/2008 29.3 1.6 76.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.37; 3B, 3C, book 3, p
HRS Documentation Record 

March 2010 - 24 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

51, 87. 

RCOAV1711B102 MH2177 

1711 Colorado Avenue 

08/10/2007 (23.9 J) 

13.7 

(3.9 J) 

2.8 

94.6 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 58, 10, 17

RCOAV1903B112 MH2179 

1903 Colorado Avenue 

08/10/2007 (63.8 J) 

39.9

(13.2 J) 

9.4 

866 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 58, 10, 18

RCOAV1904B112 MH2180 

1904 Colorado Avenue 

08/09/2007 (32.9 J) 

18.9 

(5.5 J) 

3.9 

224 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 58, 10, 19

RCOAV1906B112 MH2181 

1906 Colorado Avenue 

08/09/2007 (35.7 J) 

20.5 

(6.9 J) 

4.9 

216 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 54, Ref. 62, 464 

RCOAV1909BY02 MH26Q3 

1909 Colorado Avenue 

07/13/2008 29.3 13.1 394 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.39; 3B, 3F, 3p. 7; Ref

RCOAV1917VG02 MH2182 

1917 Colorado Avenue 

08/09/2007 (6.8 J) 

3.9 

(3.8 J+) 

2.7 

119 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 21, Appendi49, 52, 53, 8, 11, 
HRS Documentation Record 

March 2010 - 25 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

RCOAV1922B112 MH2183 

1922 Colorado Avenue 

08/09/2007 (27.6 J) 

15.9 

(1.8 J+) 

1.3 

68.7 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 53, 61, 3, 8, 1568, 573

RCOAV1923F112 MH2184 

1923 Colorado Avenue 

08/11/2007 35.3 3.8 152 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 179, 560

RCOAV1925F112 MH2185 

1925 Colorado Avenue 

08/12/2007 (29.3 J) 

16.8 

(2.6 J+) 

1.8 

141 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 53, 8, 11, 

RMTAV1518FY02 MH26Q5 

1518 Montana Avenue 

07/15/2008 16.3 24.6 334 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.41; 3B, 3F, 37, 8, 24, 

RMTAV1708VG12 MH26Q7 

1708 Montana Avenue 

07/14/2008 67.3 1.2 75.8 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 20; Ref. 1, 4, 7, 8

RMTAV1716BY12 MH26Q8 

1716 Montana Avenue 

07/09/2008 9 11 536 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.46; 
HRS Documentation Record 

March 2010 - 26 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

3B, 3F, 3p. 8; Ref

RMTAV1722FY02 MH26R0 

1722 Montana Avenue 

07/10/2008 30.3 3.8 147 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.48; 3B, 3C, 7, 8, 29, 

RMTAV1901FY12 MH26R1 

1901 Montana Avenue 

07/10/2008 43.4 2.9 148 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, A3; Ref. 263, pp. 1290, 295

RMTAV1908F112 MH2186 

1908 Montana Avenue 

08/09/2007 (50.4 J) 

29 

(2.8 J+) 

2 

119 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 185. 

RMTAV1912F102 MH2187 

1912 Montana Avenue 

08/09/2007 (14.4 J) 

8.3 

(4.8 J) 

3.4 

331 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 188. 

RMTAV1915BY12 MH26R3 

1915 Montana Avenue 

07/13/2008 75 0.5 26.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p. 5224, 27, 311; Ref. 128. 

RMTAV1924B112 1924 Montana 08/10/2007 (55.5 J) (3.6 J+) 112 As = 1/0.49/0.43 Ref. 2, 
HRS Documentation Record 

March 2010 - 27 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

MH2189 Avenue 34.7 2.6 Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 21, Appendi49, 52, 525-26; R192-194

RRBDR2720F102 MH2190 

2720 Rainbow Dam Road 

08/11/2007 (71.9 J) 

44.9

(4.2 J) 

3 

141 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi52, 54, 529, 64, 1

RRVAV2118B112 MH2191 

2118 River Avenue 

08/10/2007 (85.2 J) 

53.3 

(4.7 J) 

3.3 

1,650 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, Ref. 62, 200, 465

RSMAV1605B112 MH2192 

1605 Smelter Avenue 

08/11/2007 (45.1 J) 

25.9 

(3.2 J+) 

2.3 

137 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, 78; Ref. 201-203

RSMAV1624B112 MH2193 

1624 Smelter Avenue 

08/11/2007 (72.6 J) 

45.4

(2.7 J+) 

1.9 

280 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, 79.Ref. 213-215

RSMAV1917FY12 MH26R5 

1917 Smelter Avenue 

07/14/2008 42.7 3.8 167 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p.56; 27, 31, 3Ref. 63, 

RSMAV2021SY12 2021 Smelter 07/14/2008 53.1 13.5 351 As = 1/0.37/0.43 Ref. 2, 
HRS Docum

M

entation Record 

arch 2010 - 28 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

MH26R6 Avenue Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 5. AD, p.57; 27, 31, 37B, 26, 5

RSMAV2233F102 MH2194 

2233 Smelter Avenue 

08/12/2007 (15 J) 

8.6 

6.7 (131 J) 

100.8 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1212, 30, 6

J The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in the sample. 

J+ The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in the sample, 

( ) Value prior to correction as per EPA guidance 9285-7-14FS “Using Qualified Data to Document an Observed Release and Observed 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 29 - MTD093291599

Source Sample Information

The source samples listed above were collected during the 2007 and 2008 sampling efforts conducted by 

START for EPA. All samples were collected as grab samples following the guidelines of the UOS TSOPs 

using stainless steel spoons, bowls, and hand augers to collect the soil into 12X12 inch seal top poly bags. 

The 0-2 inch horizon was collected directly into the plastic zip lock bag using a stainless steel spoon and the 

6-12 inch horizon was collected using a hand auger into a stainless steel bowl where the soil was 

homogenized by stirring before a sample was collected into 12X12 inch seal top poly bags (Ref. 5, p. 11; Ref. 

21, pp. 11-12). All soil samples collected were analyzed in the field using a portable XRF unit (Ref. 5, p. 12; 

Ref. 21., p. 12). All samples that were analyzed in a fixed laboratory were analyzed through the EPA CLP, 

RAS for TAL total metals. Soil Samples for the 2007 investigation were delivered to A4 Scientific Inc. of 

The Woodlands, Texas on August 13, 2007 (Ref. 60, p. 3; 61, p. 3; Ref. 62, p. 3). The samples collected in 

2007 were analyzed by EPA CLP method ILM05.4 (Ref. 60, p. 1; Ref. 61, p. 1; Ref. 62, p. 1). The analytical 

data was validated by TLI Solutions on December 7, 2007 (Ref. 51, p. 1). Soil samples for the 2008 

investigation were delivered to Chemtech Consulting Group of Mountainside, New Jersey on July 18, 2008 

(Ref. 63, p. 2, Ref. 64, p. 2). The analytical data was validated by TechLaw, Inc, of Golden Colorado on 

December 03, 2008 (Ref. 27, p. 1). All samples collected in 2008 were analyzed by EPA CLP method 

ILM05.4 (Ref. 5, p. 12; Ref. 21, p. 12; Ref. 63, p. 1; Ref. 64, p. 1). Analytical results from the soil samples 

indicate the presence of arsenic, cadmium, and lead at concentrations greater than three times background. 

2.2.1.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Containment Description Containment Value References 

Gas release to air: NS - 

Particulate release to air: NS - 

Release to groundwater: NS - 

Release via overland migration and/or flood: 

There is no documentation of a maintained engineered 

cover or and functioning and maintained run-on control 

system and runoff management system. Building pads, 

streets, sidewalks, etc. cover less than half of the area, 

but are not engineered containment features. Surface 

water runoff flows directly into the Missouri River 

through a series of culverts. 

10 Ref. 1, p. 51588, 

Table 2-2, p. 

51609, Table 4-2; 

Ref. 5, 

Appendices C and 

D; Ref. 21, 

Appendix C; Ref. 

55. 

Notes: NS = Not Scored 

2.4.2 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

Description

There are no Hazardous Constituent Quantity data available for the residential soil in Black Eagle, Montana to 

calculate a Hazardous Constituent Quantity value.

 Sum (pounds): Not available (NA) 

 Hazardous Constituent Quantity Assigned Value: NA 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 30 - MTD093291599

2.4.2.1.2 Hazardous Wastestream Quantity

Description

Data are not available; it is not possible to calculate the Hazardous Wastestream Quantity. 

 Sum (pounds): NA 

 Sum of Wastestream Quantity/5000 (Ref. 1, Table 2-5): NA 

 Hazardous Wastestream Quantity Assigned Value: NA 

2.4.2.1.3 Volume

Description: 

The volume of contaminated soil has not been fully characterized; it is not possible to adequately determine 

the volume of this source. 

 

Dimension of source (yd3

): NA 

Volume Assigned Value: 0 

2.4.2.1.4 Area

Description

Arsenic and cadmium results delineate an area of approximately 1,926,569 square feet (ft2

) (Ref. 22, p. 2). 

Area Assigned Value: 1,926,569 ft2

 

2.4.2.1.5 Source Hazardous Waste Quantity Value 

1,926,569 ft2

 /34,000 = 56.66 

Highest assigned value calculated from Ref. 1, p. 51591, Table 2-5: 56.66 

 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 31 - MTD093291599

2.2.1 SOURCE IDENTIFICATION 

Name of the Source: East Ditch Dump

Number of Source: 2

Source Type: Landfill

Description and Location of the source: 

East ditch dump is on a ridge above the Missouri River approximately 400 feet north of the River and 

approximately 3,500 feet east of the former stack (Ref. 18, Figure 2; Ref. 58, Appendix I). No continuous cap 

or soil cover is documented to be in place over the east ditch dump. Building/construction debris, stained 

soils, blister copper, and slag were observed on the surface and mixed in the soil throughout the landfill area 

during the 2003 EPA site inspection (Ref. 18, pp. 17, 22, and 32; Ref. 53, 1 page). 

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

 

Hazardous Evidence (total metals) 

Substance Sample No. / 

CLP No. 

Concentration 

(mg/kg) 

Background 

References 

Arsenic AM-SO-03 / 

MX0XH0 

377 23.1 

Cadmium AM-SO-03 / 

MX0XH0 

89.8 1.2 J+ 

Lead AM-SO-03 / 

MX0XH0 

4270 30.1 

Manganese AM-SO-03 / 

MX0XH0 

899 - 

Zinc AM-SO-03 / 

MX0XH0 

4060 - 

Ref. 18, p. 94; Ref. 21, 

p. 29-32; Ref. 51, pp. 

2, 5, 9, 16, 17, 117, 

120, 124, 138; Ref. 52. 

pp. 15-16, 28; Ref. 60, 

pp. 1, 3, 6, 8, 18, 78, 

363-365, 594, 599, 

604; Ref. 61, pp. 1, 3, 

5, 8, 9, 13-14, 219-224

Source Sample Information

The source sample listed above was collected in April 2003 during the Expanded Site Inspection conducted 

by Tetra Tech EM Inc. for EPA. All samples were analyzed through the EPA CLP, RAS for total metals. 

Soil samples for inorganic analysis were delivered to Sentinal Inc, of Huntsville, Alabama (Ref. 18, p. 3). The 

analytical data was validated by Tetra Tech, EM, Inc, of Chicago, IL on July 30, 2003 (Ref. 18, p. 56). 

Analytical results from the sample indicate the presence of arsenic, cadmium, copper, lead, manganese, silver, 

and zinc in the East Ditch Dump (Ref. 18, p. 94). 

Background Sample Information

The sample collected from the East Ditch Dump is compared to soil samples collected during the 2007 EPA 

Site Inspection. The East Ditch Dump sample was collected from the 0 to 24 inch horizon using a macrocore 

(Ref. 57, 1 page). The 0-2 inch horizon background soil sample was collected directly into a plastic seal top 

bag using a stainless steel spoon and the 6-12 inch horizon was collected with a hand auger into a stainless 

steel bowl where the soil was lightly homogenized by stirring before a sample was collected into 12X12 inch 

seal top poly bags (Ref. 5, p. 11; Ref. 21, pp. 11-12). The background samples were collected from the area 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 32 - MTD093291599

north of the Missouri River, west of the site, in soils developed on the Kootenai Formation (Ref. 10. 1 sheet). 

The soil was moist, fine-grained well sorted silty sand at the locations (Ref. 52, pp. 15-16 & 28). 

The highest background sample values available for the surface soil are 23.1 mg/kg arsenic, 1.2 J+ mg/kg for 

cadmium, and 30.1 mg/kg for lead. 
 

 

 *ACM Smelter and Refinery – Background Samples 0-2 inch horizon collected in 2007 and 2008 (mg/kg) 

Analyte CRDL/ 

MDL(2007/2008) 

Jaycee Park 

R04ST2400F102 

CLP - MHIH26 

Sampled 

8/10/2007 

North Middle 

School 

R08ST2601F102 

CLP - MH1H34 

Sampled 8/8/2007 

724 25th Ave. 

R25AV0724FY02 

CLP - MH26P6 

Sampled 7/11/2008 

737 25th Ave. 

R25AV0737SY02 

CLP - MH26P7 

Sampled 7/11/2008 

Arsenic 1/(0.49/0.37) 13.3 (10.4 J) 18.1 6.3 16.1 

Cadmium 0.5/(0.20/0.040) 1.2 J+ 0.82 J+ 0.53 (0.34 J) 0.48 

Lead 1/(0.49/0.25) 30.1 (17.5 J) 25.2 25.3 20.6 

Reference Ref. 64, p. 51; 

Ref. 60, p. 64; 

Ref. 61, p. 64. 

Ref. 21, p. 29; 

Ref. 51, pp. 

117, 120, 124, 

138; 

Ref. 52. p. 28; 

Ref. 60, pp. 1, 

3, 6, 8, 18, 78, 

363-365, 594, 

599, 604; 

Ref. 21, p. 29; 

Ref. 51, pp. 2, 5, 

9, 16; Ref. 52, 

pp. 15-16; Ref. 

61, pp. 1, 3, 8, 

9, 13, 219-221, 

560, 566, 570, 

Ref. 5, pp. 28-31, 

Appendix C, p. 56. 

Ref. 24, p. 3, 

Ref. 27, pp. 2, 3B, 

3C, 3F, 3G, 3H, 9; 

Ref. 36, book 2, p. 

3 & book 3, pp. 

17-18; Ref. 64. pp. 

1, 4, 7, 9, 15, 79. 

Ref. 5, p. 28, & Appendix 

C, p. 55. Ref. 24, p. 2. Ref. 

27, pp. 2, 3B, 3C, 3G, 3H, 

10; Ref. 36, Book 2, p. 3; 

Ref 64, pp. 1, 4, 7, 9, 16, 

80. 

Bold Indicates background value selected for the contaminated landfill soil / mg/kg 

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram 

**ACM Smelter and Refinery – Background Samples 6-12 inch horizon collected in 2007 (mg/kg) 

Analyte CRDL/MDL Jaycee Park 

R04ST2400F112 

CLP - MHIH27 

Sampled 8/10/2007 

North Middle 

School 

R08ST2601F112 

CLP - MH1H35 

Sampled 8/8/2007 

724 25th 

Ave. 

6-12 inch 

sample not 

collected in 

2008 

737 25th 

Ave. 

6-12 inch 

sample not 

collected in 

2008 

Arsenic 1/0.49 17.2 (13.3 J) 23.1 - -

Cadmium 0.5/0.20 0.43 J+ 0.67 J+ - -

Lead 1/0.49 10.6 (12.9 J)18.6 - -

Reference Ref. 60, p. 64; 

Ref. 61, p. 64. 

Ref. 21, pp. 29-32; Ref. 51, 

pp. 117, 120, 124, 139; Ref. 

52. p. 28; Ref. 60, pp. 1, 3, 

5, 6, 8, 19, 117, 120, 124, 

139, 366-368. 

Ref. 21, pp.29-32; 

Ref. 51, pp. 2, 5, 9, 

17; Ref. 52, pp. 15-

16; 

Ref. 61, pp. 1, 3, 5, 

8, 9, 14, 222-224 

- -

Bold Indicates background value selected for the contaminated landfill soil / mg/kg 

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram 

HRS Documentation Record ACM Smelter and Refinery
 

March 2010 - 33 - MTD093291599
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 34 - MTD093291599

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Containment Description Containment Value References 

Gas release to air: NS - 

Particulate release to air: NS - 

Release to groundwater: NS - 

Release via overland migration and/or flood: 

No continuous maintained engineered cover, cap or soil 

cover is documented to be in place over the east ditch 

dump and waste was observed in the upper two feet of 

soil at the site in 2003. There is no documentation of a 

run-on control system and run-off is allowed to flow 

unchecked to concrete channels which direct run-off 

southward to the Missouri River. 

10 Ref. 1, p. 51588, 

Table 2-2; p 

51609, Table 4-2; 

Ref 53, 1 page. 

Notes: NS = Not Scored 

2.4.2 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

Description

There are no Hazardous Constituent Quantity data available for the East Ditch Dump to calculate a Hazardous 

Constituent Quantity value.

 Sum (pounds): Not available (NA) 

 Hazardous Constituent Quantity Assigned Value: NA 

2.4.2.1.2 Hazardous Wastestream Quantity

Description

There are no data available for the East Ditch Dump to calculate the Hazardous Wastestream Quantity. 

 Sum (pounds): NA 

 Sum of Wastestream Quantity/5000 (Ref. 1, Table 2-5): NA 

 Hazardous Wastestream Quantity Assigned Value: NA 

2.4.2.1.3 Volume

Description: 

The volume of contaminated soil at the East Ditch Dump has not been fully characterized; it is not possible to 

adequately determine the volume of this source. 

 

Dimension of source (yd3

): NA 

Volume Assigned Value: 0 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 35 - MTD093291599

2.2.2.4.4 Area

Description

The area covered by the East Ditch Dump is currently not quantifiable; however as contamination has been 

documented at the source can be said to be unknown but greater than zero (see Source 2, section 2.2.2 of this 

HRS documentation record; Ref. 58, Appendix I). 

Area Assigned Value: Unknown but >0 

2.4.2.1.4 Source Hazardous Waste Quantity Value 

>0/3,400 = >0 

The Source Hazardous Waste Quantity Value for the East Ditch is unknown but > 0 (Ref. 1, Section 2.4.2.1.5, 

Table 2-5, p. 51591). 

 Source Hazardous Waste Quantity Value: > 0 

SUMMARY OF SOURCE DESCRIPTIONS

Available to Pathway (X) 

Surface Water (SW) Air 

Source 

No. 

Source 

Hazardous 

Waste 

Quantity 

Value 

Source Hazardous 

Constituent 

Quantity Complete? 

(Y/N) 

Groundwater 

(GW) Overland/ 

flood 

GW to 

SW 

Gas Particulate

1 56.66 N NS X NS NS NS 

2 > 0 N NS X NS NS NS 

Total 56.66 

Description of Other Possible Sources: 

Fourteen additional source areas on the ACM Smelter and Refinery property were identified and sampled 

in April of 2003 by Tetra Tech EM, Inc. for an EPA Expanded Site Inspection (Ref. 18, pp. 8, 18-22, 

38). Soil cover of these sources ranged from non-existent to 10 inches deep (Ref. 1, p. 51646, Section 

5.01; Ref. 18, p. 22). The contaminates associated with one or more of these sources included antimony, 

arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, 

and zinc (Ref. 18, pages 19-20). Culverts have been identified that drain surface water from the ACM 

Smelter and Refinery property directly into the Missouri River (Ref. 23, p. 31). The following table 

describes these possible sources: 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 36 - MTD093291599

 Samples of Other Possible Sources 

 (Ref. 18, pp 18-20, 22, 32, 92, 93, 95-104, 117, 118) 

Sample Location 

Description 

Sample 

Number Contaminant Levels (ppm – mg/kg) 

Soil 

Cover 

(inches)

Waste pile in zinc 

plant dump 

AM-SO-01 Cd – 70.8, Cu – 1,440, Pb – 5,190, Ag – 14.7, Zn – 

20,700 

8 

Former lagoon area AM-SO-02 Cd – 14.0, Cu – 346, Pb – 90, Ag – 2.8J, Zn – 1,350 6 

Landfill AM-SO-04 Cd – 1.7, Cu – 71.5, Pb – 17.3, Ag – .67J, Zn – 114 0 

West ditch dump AM-SO-05 Cd – 13.1, Cu – 239, Pb – 111, Ag – .8J, Zn – 2,150 4 

Slag dump AM-SO-06 Cd – 189, Cu – 1,250, Pb – 3,120, Ag – 15J, Zn – 

21,500 

0 

Electric copper 

Refinery 

AM-SO-07 Cd – 443, Cu – 2,370, Pb – 2,630, Ag – 30.2 J, Zn – 

22,900 

0 

Arsenic Plant AM-SO-08 Cd – 4.9, Cu – 669, Pb – 45.5, Ag – 1.9J, Zn – 322 10 

North of the electric 

copper Refinery 

AM-SO-09 Cd – 28.4, Cu – 13,400, Pb – 1,230, Ag – 91.9 J, Zn – 

2,430 

8 

Zinc plant AM-SO-10 Cd – 479, Cu – 2,530, Pb – 7,070, Ag – 48 J, Zn – 

38,700 

0 

Aluminum rolling 

mill 

AM-SO-11 Cd – 17.6, Cu – 8,090, Pb – 371, Ag – 3 J, Zn – 3,200 0 

Copper rod mill AM-SO-12 Cd – 3.9, Cu – 2,470, Pb – 107, Ag – .38 UJ, Zn – 672 0 

West of the general 

laboratory 

AM-SO-13 Cd – 1.1U, Cu – 30, Pb – 10.2, Ag – 2.1 UJ, Zn – 119 9 

West of the general 

laboratory 

AM-SO-14 Cd – 303, Cu – 4,360, Pb – 1,350, Ag – 9.4J, Zn – 5,810 8 

Near smelter 

buildings 

AM-SO-15 Cd – 180, Cu – 721, Pb – 40, Ag – 3.7J, Zn – 1,970 5 

J The analyte was positively identified; the associated numerical value is the approximate concentration in the sample 

U the analyte was analyzed for, but was not detected above the reported sample quantitation limit. 

ppm parts per million 

mg/kg milligrams per kilogram 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 37 - MTD093291599

4.0 SURFACE WATER MIGRATION PATHWAY

4.1 OVERLAND/FLOOD MIGRATION COMPONENT

4.1.1.1 Definition of Hazardous Substance Migration Path for Overland/Flood Component 

Two sources have been evaluated at the ACM Smelter and Refinery site. The first source, Source 1, the 

contaminated soil in the community of Black Eagle (Ref. 22, p. 2) would enter the surface water pathway of 

the Missouri River via a series of culverts draining surface water runoff from the community into the Missouri 

River. All outfall culvert locations are on the north bank of the Missouri River and are identified from 

information provided by the Cascade County Public Works Department (Ref. 55, 12 pages; Ref. 59, pp. 1-2). 

The five of the outfall locations are listed in the following table. A map showing the locations is also 

provided (Ref. 50, 1 page). 

Outfalls draining from Contaminated Residential Soil to the Missouri River 

(Ref. 50, p. 2; Ref. 55, 11 pages; Ref. 59, pp. 1-2) 

Outlet Name Outfall Location Outfall Description Drainage Area Responsible 

Party 

PPE#1, North 

River Road 9th to 

15th Street-No. 2 

630 feet east of 

10th Street Bridge 

24-inch diameter 

corrugated steel pipe 

37 acres 

Western Black 

Eagle 

Cascade County 

PPE#2, North 

River Road 9th to 

15th Street-No. 3 

1,400 feet east of 

10th Street Bridge 

24-inch diameter 

corrugated steel pipe 

8 acres 

Western Black 

Eagle along 

Missouri River 

Cascade County 

PPE#3, 15th Street 

Bridge North 

60 feet west of 15th

Street Bridge 

30-inch diameter 

corrugated 

132 acres 

Central Black 

Eagle 

MDT and 

Cascade County 

PPE#4, Black 

Eagle South East 

East of 15th Street 

Bridge under 

North River Rd. 

20-inch diameter 

corrugated steel pipe 

22 acres 

South central 

Black Eagle 

Cascade County 

PPE#5, Anaconda 

Hills West 

(Coulee) 

380 feet west of 

Black Eagle Dam 

Twin 36-inch 

diameter corrugated 

steel pipes 

188 acres 

Eastern Black 

Eagle, Moose 

Lodge, and golf 

course 

Cascade County 

The most upstream outfall for surface water runoff from the contaminated soil identified in the unincorporated 

community of Black Eagle would be outfall North River Road 9th to 15th Street No. 2 (PPE # 1) with a 

drainage area of approximately 37 acres ( Ref 50, 1 page; Ref. 55, p. 7; Ref. 59, pp. 1-2). This outlet captures 

runoff from western edge of the community of Black Eagle and delivers the runoff through the outfall to the 

Missouri River (Ref. 50; Ref. 59, pp. 1-2). PPE # 2 delivers runoff from approximately 8 acres in western 

Black Eagle along the Missouri River to the river at the outfall named North River Road 9th to 15th Street. 

PPE # 3 drains approximately 132 acres in central Black Eagle to the Missouri River at the outfall named 15th 

Street Bridge North. PPE # 4 drains approximately 22 acres in south central Black Eagle at the outfall named 

Black Eagle South East. The eastern area of Black Eagle, approximately 188 acres including the Moose 

Lodge and the northeast quadrant of the golf course, drains through PPE # 5 into the Missouri River (Ref. 55, 

pp. 1-11; Ref. 50, 1 page; Ref. 59, pp.1-2). The surface water pathway for source 1-residential soil, would 

continue through Black Eagle Dam, past the sample collection locations of the 2003 and 2009 EPA 

investigations, through Rainbow Dam and Morony Dam to the 15-mile target distance limit (TDL) (Ref. 50, 1 

page). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 38 - MTD093291599

The probable point of entry (PPE #6) for wastes associated with source 2-the East Ditch Dump on the ACM 

Smelter and Refinery property is shown on the surface water pathway map (Ref. 18, p. 38; Ref. 50; Ref. 58, 

Appendix I). The overland flow route from the East Ditch Dump to the Missouri River is south off the ridge 

to the river through a gully for approximately 400 feet to the Missouri River (Ref. 4, map 1; Ref. 50; Ref. 58, 

Appendix I). However, other sources at the facility likely also have potential to release by overland flow due 

to lack of cover, the natural slope of the land toward the Missouri River, and culverts that drain surface water 

directly into the Missouri River (Ref. 18, p. 19, 20, 22, 32, & 38; Ref. 23, p. 31). The surface water pathway 

from PPE#6 would continue past the sample collection locations of the 2003 and 2009 EPA investigations, 

through Rainbow Dam and Morony Dam to the 15-mile target distance limit (TDL) (Ref. 50, 1 page). 

No information was found regarding existing surface water intakes on the 15-mile downstream segment. 

The stretch of the Missouri River between Black Eagle Dam and Rainbow Dam is an active fishery. Fishing 

was observed by the sampling team during the 2009 Expanded Site Inspection (Ref. 23, pp. 28 & 33). The 

Montana Department of Fish, Wildlife and Parks estimates that a population of 1,292 rainbow trout and 302 

brown trout are found in the 1.5 mile stretch between Black Eagle Dam and Giant Springs State Park (Ref. 34, 

p. 1). The fish that are caught along this stretch of the river are eaten by the anglers and their families (Ref. 

44, 1 page; Ref. 45, 1 page; and Ref. 46, 1 page). 

Approximately 0.1 mile of HRS eligible wetland frontage has been identified in the Missouri River within the 

zone of actual contamination by the US Fish and Wildlife Service as part of the National Wetlands Inventory 

(Ref. 35, pp. 1-3). 

Recreational use of the Missouri River downstream of Black Eagle Dam include Giant Springs State Park and 

its associated fish hatchery and a recreational walking and cycling path, the River’s Edge Trail (Ref. 40, pp. 

1-4; Ref. 41, p. 1). 

4.1.2.1 Likelihood of Release

4.1.2.1.1 Observed Release

Direct Observation

The Boston and Montana smelter routinely dumped large quantities of granulated slag and tailings into the 

Missouri River (Ref. 6, p. 42; Ref. 15, p. 1). In 1907, the Boston and Montana Consolidated Copper and 

Silver Mining Company estimated that the facility could receive up to 4800 tons a day of ore and changing 

the disposal of slag to railcar would significantly increase rail traffic (Ref. 14, p. 1). The Montana Department 

of Environmental Quality (Montana DEQ) estimates that between 27,500,000 and 31,000,000 cubic yards of 

waste were dumped into the Missouri River between 1893 and 1915 until onsite containment was instituted in 

1915. Montana DEQ also reports that it is possible that dumping of waste into the Missouri River continued 

at a reduced rate after 1915 until the facility closed in the 1970s (Ref. 16, p. 1). So much smelter waste was 

dumped into the Missouri River between 1893 and 1915 that the management and legal department of the 

Boston and Montana Company were concerned that the Federal Government would intervene and enjoin the 

deposition of tailings into the Missouri River by virtue of the constitutional provisions requiring the federal 

government to maintain navigable streams (Ref. 15, pp. 1 and 2). In 1884 Judge Lorenzo Sawyer of the 

United States Circuit Court in San Francisco had granted a perpetual injunction against hydraulic mining in 

California’s American River on these very grounds (Ref. 6, p. 38). 

Numerous complaints were filed by property owners and communities along the Missouri River downstream 

of the ACM Smelter and Refinery of water quality issues and slag and smelter waste clogging the Missouri 

River (Ref. 6, p. 42; Ref. 29, p. 8A). These complaints increased after the 1908 flood of the Missouri River 

inundated the community of Fort Benton, 40 miles downstream of the Boston and Montana Smelter with 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 39 - MTD093291599

smelter waste (Ref. 6, p. 38; Ref. 29, p. 8A). A company analysis of slime (very fine grained slag and 

tailings, which tended to float in the Missouri River) taken above Rainbow Falls Dam in 1914 indicated that 

the slime contained between .55 and 1.1 percent copper (Ref. 17, p. 1). The Boston and Montana Company 

sought to buy off disgruntled property owners and placate communities by providing alternate domestic water 

sources (Ref. 6, pp. 49-51). 

Cindery slag material was also currently observed to be in the sediments of the Missouri River adjacent to 

the ACM Smelter and Refinery facility (Ref. 23, p. 57 and 202, Ref, 53 p. 1; Ref. 54, p. 1). 

Chemical Analysis

Eight sediment samples from the Missouri River were collected by Tetra Tech EM, Inc for the EPA’s 

Expanded Site Inspection in April 2003. These samples were collected from the north bank of the Missouri 

River and consisted of medium to medium fine grained tan particles (Ref. 54, 1 page). All samples were 

analyzed through the EPA CLP, RAS for TAL total metals. Soil samples for inorganic analysis were 

delivered to Sentinal Inc, of Huntsville, Alabama (Ref. 18, p. 3). The analytical data was validated by Tetra 

Tech, EM, Inc, of Chicago, IL on July 30, 2003 (Ref. 18, p. 56). The following table provides analytical data 

to document the observed release by chemical analysis with the background sample and the most downstream 

samples with results greater than three times background (Ref. 18, Table 5, pp. 49-50). 

Analyses of sediment samples collected during the April 2003 sampling event indicate that concentrations of 

arsenic, cadmium, copper, lead, manganese, and zinc are significantly above background concentrations in the 

Missouri River for a distance of 2.39 miles downstream of the probable point of entry (PPE) at the Black 

Eagle Dam (Ref. 18, p. 39, Figure 3). According to the HRS, if an observed release can be established, a 

value of 550 is assigned for Likelihood of Release (Ref. 1, Section 4.1.2.1.1, p. 51609). 

Seven release sediment samples were collected by START for the EPA Region 8 on July 14, 2009. All 

release samples were collected by boat from the north side of the Missouri River from beneath the water. A 

background sample (AGFSED1) was collected from the north bank of the Missouri River, downstream of the 

Montana Refining Company facility and upstream of the outfall North River Road 9th to 15th Street No. 3 

(PPE#1) and the community of Black Eagle (Ref. 50, 1 page). The samples were analyzed by Compuchem 

Laboratory in Cary, North Carolina, for total Target Analyte List (TAL) metals analysis with a supporting 

Level 4 data package (Ref. 23, pp 6, 15, & 21). The data package was validated by a START chemist who 

determined that the background cadmium result was biased high as well as two downstream results (Ref. 23, 

pp. 77-198). The analytical data was revised in accordance with the EPA guidelines for using qualified data, 

which resulted in the high bias for the background sample being retained while the two downstream, 

analytical results were revised downward (Ref. 43, pp. 1-9, 18). The following table provides analytical data 

to document the observed release by chemical analysis. 

Analyses of sediment samples collected during the July 2009 sampling event indicate that concentrations of 

lead are above background concentrations in the Missouri River for a distance of 2.39 miles downstream of 

the probable point of entry (PPE) at the Black Eagle Dam (Ref. 24, p. 28, Table 3; Ref. 50). According to the 

HRS, if an observed release can be established, a value of 550 is assigned for Likelihood of Release (Ref. 1, 

Section 4.1.2.1.1, p. 51609). 
Sediment Samples Collected from the Missouri River adjacent and downstream of the ACM Smelter and Refinery, July 

Sample ID Sample Location Sample 

Date 

Cadmium (Cd) mg/kg 

Lead (Pb) mg/kg 

CRQL/ Refere

AGFSED1 0907118-01 

Background Sample at 11th Street 07/14/09 0.36 J+ 12.3 Cd :0.06 

Pb: 0.21- 

Ref. 2, 23, pp. 70, 85182, 18

AGFSED2 0907118-02 

1.89 miles downstream of PPE No. 1 07/14/09 (11.7 J+) 

8.3 

168 Cd: 0.06 

Pb: 0.21- 

Ref. 2, 23, pp. 70, 85, 182, 18

AGFSED3 0907118-03 

1.95 miles downstream of PPE No. 1 07/14/09 11.8 78.4 Cd: 0.06 

Pb: 0.21 

Ref. 2, 23, pp. 70, 85192, 20

AGFSED4 0907118-04 

2.06 miles downstream of PPE No. 1 07/14/09 3.9 18.9 Cd: 0.06 

Pb: 0.21 

Ref. 2, 23, pp. 70, 85193, 20

AGFSED5 0907118-05 

2.39 miles downstream of PPE No. 1 07/14/09 (4.2 J+) 

2.9 

49.9 Cd: 0.06 

Pb: 0.21 

Ref. 2, 23, pp. 70, 85182, 18

Notes: J+ The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in the sample, ( ) Value prior to correction (Ref. 43, p. 13) mg/kg milligrams per kilogram CRQL Contract Required Quantitation Limit SCDM Superfund Chemical Data Matrix HRS Documentation Record March 2010 - 40 - 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 41 - MTD093291599

Attribution:

Residential soil contamination in the unincorporated residential community of Black Eagle located on the 

north bank of the Missouri River across from Great Falls, Montana, was first documented by the EPA’s 2003 

Expanded Site Inspection when elevated concentrations of antimony, arsenic, cadmium, chromium, cobalt, 

copper, iron, lead, manganese, mercury, nickel, silver, sodium, and zinc were found in one or more samples 

(Ref. 4, map 1; Ref. 18, pp. 28-30). 

The 2007 EPA CERCLA Site Assessment sampled residences on both the north and south sides of the 

Missouri River adjacent to the Anaconda Minerals Co, Great Falls Refinery (Ref. 21, p. 11). Of the eleven 

residences sampled in Great Falls on the south side of the Missouri River in August of 2007 only one 

residence had an elevated concentration of arsenic (Ref. 21, p. 13). The results of the 2007 investigation of 

the residential soil in the community of Black Eagle identified an area of arsenic, cadmium, and lead 

concentrations greater than three times background centered on eastern and central Black Eagle (Ref. 21, p. 

13-14, 18). 

The 2008 EPA CERCLA Expanded Site Investigation was focused in the unincorporated community of Black 

Eagle, Montana. The residential soil at fifty nine residential properties in Black Eagle was sampled in July 

2008 to a depth of one foot (Ref. 5, p. 1). Concentrations of arsenic, cadmium, and lead elevated three times 

background were detected in the residential soil in Black Eagle centered on the central and southwestern area 

of Black Eagle (Ref. 5, p. 13; Ref. 22, pp. 1-2). 

The East Ditch Dump and fourteen additional source areas on the ACM Smelter and Refinery property were 

identified and sampled in April of 2003 by Tetra Tech EM, Inc. for an EPA Expanded Site Inspection (Ref. 

18, pp. 8, 18-22, 38). There is no record of maintained engineered run on and run off structures and the 

observations of the soil cover of the sources during the 2003 sampling event ranged from non-existent to 10 

inches deep which makes the contaminants from these sources available for migration (Ref. 1, p. 51646, 

Section 5.01; Ref. 18, p. 22). The contaminates associated with one or more of these sources included 

antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, 

silver, and zinc (Ref. 18, pp. 19-20). Culverts have been identified that drain surface water from the ACM 

Smelter and Refinery property directly into the Missouri River (Ref. 18, pp. 28, 31, ). 

Sediment samples from the north bank of the Missouri River were collected by boat on July 14, 2009 (Ref. 

23, p. 16). The samples were shipped to CompuChem in Cary, North Carolina on July 15, 2009 (Ref. 23, p. 

41). The analytical results were validated by URS Operating Services on July 24, 2009 (Ref. 23, p. 177). The 

sediment sample material was a grey to brown fine to medium grain size river sand with small to medium 

sized grains of black and rust colored cindery material mixed with the sand (Ref. 23, p. 202). The grab 

samples of sediment were analyzed for metals by EPA CLP method SW846 (Ref. 23, p. 40). Cadmium and 

lead elevated three times background was detected for a total distance of 2.39 miles downstream of PPE #1 

(Ref. 23, p. 23; Ref. 50). 

The Boston and Montana smelter routinely dumped large quantities of granulated slag and tailings into the 

Missouri River (Ref. 6, p. 42; Ref. 15, p. 1). In 1907, the Boston and Montana Consolidated Copper and 

Silver Mining Company estimated that the facility could receive up to 4800 tons a day of ore and changing 

the disposal of slag to railcar would significantly increase rail traffic (Ref. 14, p. 1). The Montana 

Department of Environmental Quality (Montana DEQ) estimates that between 27,500,000 and 31,000,000 

cubic yards of waste were dumped into the Missouri River between 1893 and 1915 until onsite containment 

was instituted in 1915. Montana DEQ also reports that it is possible that dumping of waste into the Missouri 

River continued at a reduced rate after 1915 until the facility closed in the 1970s (Ref. 16, p. 1). So much 

smelter waste was dumped into the Missouri River between 1893 and 1915 that the management and legal 

department of the Boston and Montana Company were concerned that the Federal Government would 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 42 - MTD093291599

intervene and enjoin the deposition of tailings into the Missouri River by virtue of the constitutional 

provisions requiring the federal government to maintain navigable streams (Ref. 15, pp. 1 and 2). In 1884 

Judge Lorenzo Sawyer of the United States Circuit Court in San Francisco had granted a perpetual injunction 

against hydraulic mining in California’s American River on these very grounds (Ref. 6, p. 38). 

Numerous complaints were filed by property owners and communities along the Missouri River downstream 

of the ACM Smelter and Refinery of water quality issues and slag and smelter waste clogging the Missouri 

River (Ref. 6, p. 42; Ref. 29, p. 8A). These complaints increased after the 1908 flood of the Missouri River 

inundated the community of Fort Benton, 40 miles downstream of the Boston and Montana Smelter with 

smelter waste (Ref. 6, p. 38; Ref. 29, p. 8A). A company analysis of slime (very fine grained slag and 

tailings, which tended to float in the Missouri River) taken above Rainbow Falls Dam in 1914 indicated that 

the slime contained between .55 and 1.1 percent copper (Ref. 17, p. 1). The Boston and Montana Company 

sought to buy off disgruntled property owners and placate communities by providing alternate domestic water 

sources (Ref. 6, pp. 49-51). 

Cindery slag material was also currently observed to be in the sediments of the Missouri River adjacent to 

the ACM Smelter and Refinery facility (Ref. 23, p. 57 and 202, Ref, 53 p. 1; Ref. 54, p. 1). 

The former Montana Silver Smelter site is located on the south bank of the Missouri River in Giant Springs 

State Park, approximately 2.85 miles east-northeast of the 15th Street Bridge (Ref. 4, 2 pages; Ref. 50, p. 1). 

The Montana Silver Smelter was constructed in 1888 by Great Falls city father, Paris Gibson (Ref. 56, p. 2). 

The smelter had two small stacks. Many of the structures at Giant Springs State Park and Giant Springs State 

Fish Hatchery were built on mineral processing wastes that contained extremely high levels of arsenic and 

lead. This property was cleaned up by the Montana Mine Waste Cleanup Bureau’s Abandoned Mine Lands 

Program in 2004 (Ref. 57, pp. 9-11). The Montana Refining Company facility is located upstream of the 

unincorporated community of Black Eagle on the north bank of the Missouri River (Ref. 50, 1 map). The 

Montana Refining Company produces various grades of gasoline, diesel, jet fuel, distillates, and high grade 

asphalt products (Ref. 65, 1 page.). The facility has an operable capacity of 9,500 barrels per calendar day 

ranking the facility as number 132 of the 143 U.S. Refineries (Ref. 66, p. 4). 

Both of the operations could potentially have contributed to the contamination documented in the Missouri 

River; however, the contamination found in the Missouri River sediments is at least partially attributable to 

the sources found on the ACM Smelter and Refinery property because of the evidence presented above. 

4.1.2.1.2 Potential to Release

Potential to Release by overland flow was not evaluated because an observed release was established (Ref. 1 

Section 4.1.2.1.2, p. 51609). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 43 - MTD093291599

4.1.3.2 Human Food Chain Threat Waste Characteristics 

4.1.3.2.1 Toxicity/Persistence/Bioaccumulation 

Hazardous 

Substance 

Source 

No. 

Toxicity 

Factor 

Value 

Persistence 

Factor 

Value* 

Bioaccumulation 

Value** 

Toxicity/ 

Persistence/ 

Bioaccumulation 

Factor Value 

(Table 4-16) 

References 

Arsenic 1 & 2 10,000 1.0 5.0 5 X 104 Ref. 2, p. BI-1 

Cadmium 1 & 2 10,000 1.0 5,000 5 X 107 Ref. 2, p. BI-2 

Lead 1 & 2 10,000 1.0 5.0 5 X 104 Ref. 2, p. BI-8 

Manganese 2 10,000 1.0 50,000 5 x 108 Ref. 2, p. BI-8 

Zinc 2 10 1.0 5.0 50 Ref. 2, p. BI-12 

Notes: * Persistence value for Rivers 

** Bioaccumulation factor value for Freshwater 

The Toxicity/Persistence/Bioaccumulation Factor Value for manganese is 5 x 108

(Ref. 1, Section 4.1.3.2.1.4, 

Table 4-16; Ref. 2, p.BI-8). 

Toxicity/Persistence/Bioaccumulation Factor Value: 5 x 108

4.1.3.2.2 Hazardous Waste Quantity

Source No. Source Type Source Hazardous Waste Quantity 

1 Contaminated Soil 56.66 

2 Landfill > 0 

Total 1 

The source hazardous waste quantity value is assigned as the Hazardous Waste Quantity Factor Value (Ref. 1, 

Section 2.4.2.2). Although a Hazardous Waste Quantity Factor Value of 1 is assigned to a site whose sum of 

Source Hazardous Waste Quantity Values is greater than 1 but less than or equal to 100 (Ref. 1, Table 2-6, p. 

51591), the presence of targets subject to Level II contamination and the fact that Tier A was not adequately 

determined means that the calculated value, or 100, whichever is greater, may be assigned (Ref. 1, Sec. 

2.4.2.2, p. 51592). 

 Hazardous Waste Quantity Factor Value (100 >1) 

Hazardous Waste Quantity Factor Value: 100 

(Ref. 1, p. 51591, Table 2-6) 

4.1.3.2.3 Waste Characteristics Factor Category Value

Toxicity/Persistence/Bioaccumulation Factor Value: 5 x 108

Hazardous Waste Quantity Factor Value: 100 

Toxicity/Persistence x Hazardous Waste Quantity: 1 x 106

 

Toxicity/Persistence/Hazardous Waste Quantity x Bioaccumulation: 5 x 1010 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 44 - MTD093291599

 Waste Characteristics Factor Category Value: 320

(Ref. 1, Sec. 2.4.2.2, p. 51592, Table 2-7) 

4.1.3.3 Human Food Chain Threat Targets

Actual Human Food Chain Contamination

Sample ID Sample 

Medium 

Distance 

from PPE 

Hazardous 

Substance 

Bio-accumulation 

Factor Value 

References 

AGFSED5 

(0907118-5) 

Missouri 

River 

Sediment 

2.39 miles Cadmium 5,000 Ref. 2, p. BI-8 

Ref. 23, p. 23; 

Ref. 50 

- Closed Fisheries: 

The state of Montana has not declared any portion of the surface water pathway a closed fishery. 

- Fish Tissue: 

Fish tissue samples were collected by ARCO’s contractor Paramatrix in 2004. Paramatrix concluded that the 

concentrations in tissue were largely comparable between upstream (background) and downstream (site) 

areas. A statistical analysis of the analytical data was not performed (Ref. 19, p. 3). A review of the report by 

the EPA’s Regional Ecological toxicologist noted that at three sample locations ecotoxicological benchmarks 

were exceeded in soil samples, and it is likely that higher concentrations of metals in all samples could have 

been obtained by taking samples on the north side of the Missouri River, which is the same side as the facility 

rather than across from the facility on the south bank of the Missouri River (Ref. 20, p. 1, 2). 

Level I Fisheries

The Missouri River is not documented as having fisheries subject to Level I actual contamination (Ref. 1, p. 

51620). 

Most Distant Level II Sample

The most distant Level II observed release sediment sample, 2.39 miles downstream of PPE #1 (Ref .23, p. 

28, Ref. 50, 1 page). 

Level II Fisheries

Identity of Fishery Extent of Level II Fishery

(Relative to PPE) 

Refs. 

Missouri River 2.39 miles Ref. 23, p. 28; Ref. 34, p. 2; Ref. 50, 1 page; 

Ref. 44, Ref. 45; Ref. 46. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 45 - MTD093291599

4.1.3.3.1 Food Chain Individual

Actual contamination of the Missouri River fishery was documented by Level II concentrations in sediment 

sample AGFSED5 (0907118-05). The stretch of the Missouri River between Black Eagle Dam and Rainbow 

Dam is an active fishery. Fishing was observed and photo documented by the sampling team during the 2009 

Expanded Site Inspection at the Rainbow Boat Ramp. Photo documentation of fishing and a statement 

attesting to the consumption of fish caught in that reach of the Missouri River at the Rainbow Boat Ramp is 

documented (Ref. 23, pp. 27, 28, 33; Ref. 44, 1 page; Ref. 45; Ref. 46, 1 page). The Montana Department of 

Fish, Wildlife and Parks estimates that a population of 1,292 rainbow trout and 302 brown trout are found in 

the 1.5 mile stretch between Black Eagle Dam and Giant Springs State Park (Ref. 34, p. 1). The fish that are 

caught along this stretch of the river are eaten by the anglers and their families (Ref. 44, 1 page; Ref. 46, 1 

page). This fishery is subject to Level II concentrations, due to a release of a contaminant with a BCF of 

greater than or equal to 500; a value of 45 is assigned to the Human Food Chain Individual Factor Value (Ref. 

1, Sec. 4.1.3.3.1 and Sec. 4.1.3.3). 

Food Chain Individual Factor Value: 45 

4.1.3.3.2 Population

4.1.3.3.2.1 Level I Concentrations

Not applicable 

Level I Concentrations Factor Value: 0 

4.1.3.3.2.2 Level II Concentrations

The extent of the Level II contamination of the Missouri River fishery is 2.39 miles (distance from the most 

upstream PPE (PPE #1) in Missouri River at 11th Street in Black Eagle, Montana to Sample AGFSED05 (Ref. 

23, p. 28; Ref. 50). Exact productivity values for the Missouri River fishery are not available. Therefore, to 

be conservative, a value of >0 but, unknown will be used for production values in the Missouri River. For an 

annual production of greater than 0 to 100 pounds per year, a Human Food Chain Population Value of 0.03 is 

assigned as the Level II concentrations factor value (Ref. 1, Section 4.1.3.3.2.2, p. 51621, Table 4-18). 

Identity of Fishery Annual Production 

(pounds) 

References Human Food Chain 

Population Value 

(Table 4-18) 

Missouri River >0.0 lb./acre Ref. 1, Sec 

4.1.3.3.2.2, 

p. 51621 

0.03 

Sum of Level II Human Food Chain Population Values: 0.03 

Level II Concentrations Factor Value: 0.03 

4.1.3.3.2.3 Potential Human Food Chain Contamination 

The Missouri River downstream of sample location AGFSED05 to the 15-mile TDL may be considered a 

fishery subject to potential contamination. Sediment samples have not been collected below Rainbow Dam to 

the 15-mile TDL. Values for the amount of human food chain organisms produced annually from these 

fisheries have not been estimated, but are evaluated a greater than 0 pounds per acre. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 46 - MTD093291599

Identity of 

Fishery 

Annual 

Production 

(pounds) 

Type of Surface 

Water Body 

Average 

Annual 

Flow (cfs) 

Ref. Population 

Value (Pi) 

(Table 4-18) 

Dilution 

Weight (Di) 

(Table 4-13) 

Pi x Di

Missouri 

River 

>0 large stream to river 6733 cfs Ref. 1, 

p. 

51613, 

51621 

Ref. 13, 

p. 3 

0.03 0.001 0.00003

Sum of Pi x Di: 0.00003 

(Sum of Pi x Di)/10: 0.000003 

 Potential Human Food Chain Contamination Factor Value: 0.000003 

 Potential Human Food Chain contamination value: 0.000003 

4.1.3.3.2.4 Calculation of Population Factor Value

The population factor value is calculated by summing the value of Level I concentration (0), Level II 

concentration (0.03) and potential human food chain contamination factors (0.000003). The resulting value is 

assigned the population factor value for the watershed (Ref. 1, p. 51621, Section 4.1.3.3.2.4). 

Calculations: (0) + (0.03) + (0.000003) = 0.030003 

4.1.3.3.3 Calculation of a Human Food Chain Threat - Target Factor Category Value

The Human Food Chain Threat-Target Factor Category Value is calculated by summing the Food Chain 

Individual (45) and Population Factor Value of the watershed (0.030003). The resulting value, 45.030003, is 

assigned as the Human Food Chain Threat-Target Score (Ref. 1, p. 51620, Sec. 4.1.3.3.2). 

Food Chain Target Factor Category Value: 45.030003 

4.1.3.4 Calculation of a Human Food Chain Threat Score for a Watershed

The Human Food Chain Threat is calculated by multiplying the Human Food Chain Threat Factor Category 

Value for likelihood of release (550), Waste Characteristics (320) and Targets for a Watershed (45.030003). 

The product is rounded to the nearest integer and divided by 82,500. The resulting value, subject to a 

maximum of 100, is assigned as the Human Food Chain Threat Score for the watershed (Ref. 1, p. 51621, 

Sec. 4.1.3.4). 

Calculations: (Likelihood of Release 550)(Waste Characteristics Value 320)(Targets 45.030003) = 

7,925,280.5 

 7,925,280.5/82,500 = 96.06 

 Human Food Chain Threat Score: 96.06 
HRS Documentation Record ACM Smelter and Refinery 

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4.1.4.2 Environmental Threat Waste Characteristics

4.1.4.2.1 Ecosystem Toxicity/Persistence/Bioaccumulation

The Ecosystem Toxicity/Persistence/Bioaccumulation Values are based on the contaminants detected in the 

Source and the observed release. 

Hazardous 

Substance 

Source 

No. 

Ecotoxicity** 

Factor Value 

Persistence 

Factor 

Value*** 

(River) 

Bioaccumulation 

Factor Value 

(Env./Fresh) 

Ecotoxicity/ 

Persistence/ 

Bioaccumulation 

Factor Value Ref. 

Arsenic 1 & 2 10 1.0 5,000 5 X 104 Ref. 2, p. 

BI-1 

Cadmium 1 & 2 10,000 1.0 50,000 5 X 108 Ref. 2, p. 

BI-2 

Lead 1 &2 1,000 1.0 50,000 5 x 107

Manganese 2 0 1.0 50,000 0 

Ref. 2, 

p. BI-8

Zinc 2 10 1.0 50,000 5 X 105 Ref. 2, p. 

BI-12 

** Ecotoxicity values assigned are based on the predominant surface water category of fresh water. 

*** Persistence values assigned are based on the predominant surface water body category “River.” 

Cadmium has the highest Ecosystem Toxicity/Persistence/Bioaccumulation Factor Value for this Watershed, 

5 x 108 (Ref. 1, Table 4-21; Ref. 2, p.BI-2). Cadmium was selected to assign the value to this factor as 

directed by HRS Section 4.1.4.2.1.4 (Ref. 1, Section 4.1.4.2.1.4). 

Ecosystem Toxicity/Persistence/Bioaccumulation Factor Value: 5 x 108 

4.1.4.2.2 Hazardous Waste Quantity

The factor value derived for the drinking water threat or the human food chain threat hazardous waste 

quantity (100) is assigned to the environmental threat hazardous waste quantity factor value as directed by 

HRS Section 4.1.4.2.2 (Ref. 1, Section 4.1.4.2.2). 

Hazardous Waste Quantity Value: 100 

4.1.4.2.3. Waste Characteristics Factor Category Value

The waste characteristics factor category value is derived by first multiplying the ecotoxicity/persistence 

factor value and the hazardous waste quantity factor value for the watershed (subject to a maximum of 1 x 

108

). This product is then multiplied with the ecosystem bioaccumulation potential factor value for this 

hazardous substance as presented in Section 4.1.4.2.1 of this HRS documentation record (subject to a 

maximum value of 1 x 1012) (Ref. 1, Section 4.1.4.2.3). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 48 - MTD093291599

Ecosystem Toxicity / Persistence Factor Value = 10,000

Hazardous Waste Quantity Factor Value = 100 

10,000 x 100 = 1 x 106

Ecosystem toxicity/persistence factor value 

x hazardous waste quantity factor value: 1 x 106

Ecosystem Bioaccumulation Potential Factor Value = 50,000 

(Ecosystem toxicity/persistence x hazardous waste quantity factor value) 

 x bioaccumulation potential factor value: 

(100 x 10,000) x (50,000) = 5 x 1010

(Subject to a maximum of 1x1012) 

The value calculated is 5 x 1010. As directed by the HRS, this value is applied to HRS Table 2-7 to 

determine the Waste Characteristics Factor Category Value (Ref. 1, Sections 2.4.3.2 and 4.1.4.2.3, Table 2-7). 

Hazardous Waste Quantity Factor Value: 100 

Waste Characteristics Factor Category Value: 320 

4.1.4.3 Environmental Threat - Targets

Wetlands along the banks of the Missouri River and on Black Eagle Island and Steamboat Island in the 

Missouri River are identified by the U.S. Fish and Wildlife Service as part of the National Wetlands Inventory 

(Ref. 35, pp 1-3). Most of the wetlands immediately below Black Eagle Dam are classified as Riverine 

Perennial wetlands, and Palustrine Emergent wetlands are identified further downstream of the Black Eagle 

Dam within the zone of documented contamination (Ref. 35, pp 1-3). Most of the wetlands identified on the 

U.S. Fish and Wildlife Service National Wetlands Inventory Map for Northeast and Northwest Great Falls 

Montana within the zone of actual contamination qualify as eligible wetlands defined in 40 CFR Sec 230.2 

because most of these wetland types are likely to contain a prevalence of wetland plant species based on their 

classification such as the palustrine emergent wetlands mentioned above. 

4.1.4.3.1 Sensitive Environments

4.1.4.3.1.1 Level I Concentrations

Level I concentrations have not been established in association with the site for sample location AGFSED5 

(Ref. 23, p. 28). 

4.1.4.3.1.2 Level II Concentrations 

At least 0.1 mile of wetland frontage occurs within the zone of actual contamination and is subject to Level II 

contamination using sediment samples alone (Ref. 1, Table 4-24). 

Level II Concentrations Factor Value: 25 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 49 - MTD093291599

4.1.4.3.1.3. Potential Contamination

Sensitive Environments

No sensitive environment targets were evaluated for their potential target values. 

Potential Contamination Factor Value: NS 

4.1.4.3.1.4 Environmental Threat-Targets Factor Category Value

The environmental threat target factor category value for the watershed is the sum of the values for the 

Level I (0), Level II (25) and potential contamination factors (0) (Ref. 1, Section 4.1.4.3.1.4). 

Environmental Threat-Target Factor Category Value = 25 

4.1.4.4 Environmental Threat Score for Watershed

The environmental threat score is calculated by multiplying the environmental threat factor category 

value for likelihood of release (550), the waste characteristics (320) and targets for a watershed (25). The 

product is rounded to the nearest integer and divided by 82,500. The resulting value, subject to a 

maximum of 60, is assigned as the Environmental Threat Score for the Watershed (Ref. 1, Section 

4.1.4.4). 

Calculation: 

 550 X 320 X 25 = 4,400,000 

 4,400,000/82,500 = (subject to a maximum of 60) = 53.33 

Environmental Threat Score: 53.33
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 50 - MTD093291599

5.0 SOIL EXPOSURE PATHWAY

5.0.1 GENERAL CONSIDERATIONS

Letter by which this area is to be identified: A 

Name of area: Contaminated residential soil in Black Eagle, Montana

Residential soil contamination in the community of Black Eagle was documented by the EPA’s 2003, 2007, 

and 2008 investigations when elevated concentrations of arsenic, cadmium, chromium, copper, iron, lead, 

manganese, mercury, nickel, silver, sodium, and zinc were found in one or more samples (Ref. 5, pp. 13-14; 

Ref. 18, pp. 28-30; Ref 21 pp. 10, 13-14). 

The 2007 EPA CERCLA Site Assessment sampled residences on both the north and south sides of the 

Missouri River adjacent to the Anaconda Minerals Co, Great Falls Refinery (Ref. 21, p. 11). Of the eleven 

residences sampled in Great Falls on the south side of the Missouri River in August of 2007 only one 

residence had a elevated concentration of arsenic (Ref. 21, p. 13). Thirty-three residences were sampled for 

CLP analysis north of the Missouri River in Black Eagle in August of 2007, and arsenic and lead 

concentrations greater than three times background were identified in central and eastern Black Eagle from 

the results of the 2007 investigation (Ref. 21, pp. 13-14, 18). All soil samples collected were analyzed in the 

field using a portable XRF device (Ref. 5, p. 12; Ref. 21., p. 12). All samples for fixed laboratory analyses 

were analyzed through the EPA’s CLP, RAS. The samples collected in 2007 were analyzed by A4 Scientific, 

Inc. of The Woodlands, Texas by EPA CLP method ILM05.4 (Ref. 60, p. 1; Ref. 61., p. 1; Ref. 62, p. 1). 

The 2008 EPA CERCLA Expanded Site Investigation was focused in the community of Black Eagle, 

Montana. The residential soil at fifty-nine residential properties in Black Eagle was sampled in July 2008 to a 

depth of one foot (Ref. 5, p. 1). Concentrations of arsenic, cadmium, lead and zinc elevated three times 

background were detected in the residential soil in Black Eagle (Ref. 5, pp. 13-14; Ref. 18, pp. 28-30; Ref. 

21, pp. 13-14). Elevated arsenic and cadmium results delineated an area of contamination centered on 

southwestern and central Black Eagle (Ref. 5, pp. 13-14, 23-24). 

All 2008 soil samples collected were analyzed in the field using a portable XRF device (Ref. 5, p. 12; Ref. 

21., p. 12). All samples for fixed laboratory analyses were analyzed through the EPA’s Contract Laboratory 

Program (CLP), Routine Analytical Services. The samples collected in 2008 were analyzed by Chemtech 

Consulting Group, Mountainside, New Jersey by EPA CLP method ILM05.4 (Ref. 63. p. 1; Ref. 64, p. 1). 

Areas of contamination in which all residences are subject to actual contamination, were calculated using 

Global Positioning System (GPS) coordinates of sample locations with 2007 and 2008 arsenic and cadmium 

analytical results that were greater than three times background and above a health based benchmark (i.e., 

samples with Level I concentrations). The area was processed with GIS software (Ref. 22, p. 1; Ref. 24, p. 1). 

Background Concentrations: 

A total of four background soil samples were collected in 2007 and 2008. Two background soil samples were 

collected in 2007 and two more background soil samples were collected in 2008. All four background 

samples were collected in populated areas west of the community of Black Eagle and on the north side of the 

Missouri River from sandy-silty soils formed on the Kootenai Formation (Ref. 5, p. 5, 10; Ref. 21, p. 4, 11; 

Ref. 10, 1 sheet; Ref. 36, book 2, p. 3 & book 3, pp. 17-18; Ref. 52, pp. 15-16, 28; Ref. 49, 1 page). The 

background samples for both 2007 and 2008 were collected in the same manner as all the soil samples. 

Stainless steel hand augers, bowls, and spoons were used for soil collection. Grab soil samples were collected 

from two horizons; zero to 2 inches and 6 to 12 inches bgs. The non-disposable sampling equipment was 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 51 - MTD093291599

decontaminated between sample locations. The samples were collected into a stainless steel bowl before 

being transferred into a 12X12 inch seal top poly bag or directly into 12X12-inch seal top poly bags labeled 

with the sample identifier. Sample descriptions were logged on the field form with standard geologic 

descriptions along with a sketch map with dimensions of the property, description of the zone sampled, and 

any calculations supporting the decision. A photograph for report documentation was taken of each sample 

location showing the residence in the background of the photograph (Ref. 5, p. 11; Ref. 21, p. 11-12). 

The highest value between the four background samples is used as the background value for this document 

(Ref. 48). Background sample R04ST2400F112 was collected on August 10, 2007 from Jaycee Park 

approximately 5,900 feet west of U.S. Highway 87 (Ref. 49, p. 1). The arsenic background of 17.2 mg/kg and 

the manganese background of 374 mg/kg were taken from this background sample location. Background 

sample R08ST2601F112 was collected on August 8, 2007 from the property of North Middle School 

approximately 3,000 feet west of U.S. Highway 87 (Ref. 21, p. 26; Ref. 49, p. 1). The cadmium background 

of 0.67 mg/kg was taken from this background sample location. Background sample R25AV0724FY02 was 

collected on July 11, 2008 from the front yard of the residence at 724 25th Street, approximately 3,400 feet 

west of U.S. Highway 87 (Ref. 36, logbook # 2, p. 3; Ref. 5, p. 10; Ref. 49, p. 1). The lead background value 

of 25.3 mg/kg and the background value for zinc of 108 mg/kg were taken from this background sample 

location. The fourth background sample location was collected on July 11, 2008 from the side yard of the 

residence at 737 25th Avenue, approximately 3,500 feet west of U.S. Highway 87 (Ref. 36, logbook # 2, p. 3; 

Ref. 5, p. 10; Ref. 49, p. 1). 

The background values for arsenic, cadmium, and lead used to calculate elevated concentrations are included 

in the following table in bold: 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 52 - MTD093291599

*ACM Smelter and Refinery – Background Samples 0-2 inch horizon collected in 2007 and 2008 (mg/kg)

Analyte CRDL/ 

MDL(2007/2008) 

SCDM 

Benchmark 

RDSC 

Jaycee Park 

R04ST2400F102 

CLP - MHIH26 

Sampled 

8/10/2007 

North Middle 

School 

R08ST2601F102 

CLP - MH1H34 

Sampled 8/8/2007 

724 25th Ave. 

R25AV0724FY02 

CLP - MH26P6 

Sampled 

7/11/2008 

737 25th Ave. 

R25AV0737SY02 

CLP - MH26P7 

Sampled 

7/11/2008 

Arsenic 1/(0.49/0.37) 0.43 13.3 (10.4 J) 18.1 6.3 16.1 

Cadmium 0.5/(0.20/0.040) 39 1.2 J+ 0.82 J+ 0.53 (0.34 J) 0.48 

Lead 1/(0.49/0.25) - 30.1 (17.5 J) 25.2 25.3 20.6 

Reference Ref. 64, p. 51; 

Ref. 60, p. 64; 

Ref. 61, p. 64. 

Ref. 2, pp. 

BII-13, 

BII-14, 

BII-20 

Ref. 21, p. 29; 

Ref. 51, pp. 

117, 120, 124, 

138; 

Ref. 52. p. 28; 

 Ref. 60, pp. 

1, 3, 6, 8, 18, 

78, 363-365, 

594, 599, 604; 

Ref. 21, p. 29; 

Ref. 51, pp. 2, 

5, 9, 16; Ref. 

52, pp. 15-16; 

Ref. 61, pp. 1, 

3, 8, 9, 13, 219-

221, 560, 566, 

570, 

Ref. 5, pp. 28-31, 

Appendix C, p. 

55. Ref. 24, p. 2, 

Ref. 27, pp. 2, 

3B, 3C, 3F, 3G, 

3H, 9; Ref. 36, 

book 2, p. 3 & 

book 3, pp. 17-

18; Ref. 64. pp. 

1, 4, 7, 9, 15, 79. 

Ref. 5, p. 28, & 

Appendix C, p. 

55. Ref. 24, p. 

2. Ref. 27, pp. 

2, 3B, 3C, 3G, 

3H, 10; Ref. 

36, Book 2, p. 

3, Book 3, pp. 

17-18; Ref 64, 

pp. 1, 4, 7, 9, 16, 

80. 

* Sample IDs ending in 02 represent samples collected from 0-2 inches (Ref. 5, p. 10; Ref. 21, p. 11). 

Bold Indicates background value selected for this document / mg/kg 

CRSC Cancer Risk Screening Concentration 

RDSC Reference Dose Screening Concentration 

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram 

**ACM Smelter and Refinery – Background Samples 6-12 inch horizon collected in 2007 (mg/kg)

Analyte CRDL/ 

MDL(2007) 

SCDM 

Benchmark 

RDSC 

Jaycee Park 

R04ST2400F112 

CLP - MHIH27 

Sampled 8/10/2007 

North Middle 

School 

R08ST2601F112 

CLP - MH1H35 

Sampled 8/8/2007 

724 25th Ave. 

6-12 inch sample 

not collected in 

2008 

737 25th Ave. 

6-12 inch sample 

not collected in 

2008 

Arsenic 1/0.49 0.43 17.2 (13.3 J) 23.1 - - 

Cadmium 0.5/0.20 39 0.43 J+ 0.67 J+ - - 

Lead 1/0.49 - 10.6 (12.9 J)18.6 - - 

Reference Ref. 60, p. 64; 

Ref. 61, p. 64 

Ref. 2, pp. 

BII-13, 

BII-14, 

BII-20 

Ref. 21, pp. 29-

32; Ref. 51, pp. 

117, 120, 124, 

139; Ref. 52. p. 

28; Ref. 60, pp. 

1, 3, 5, 6, 8, 19, 

117, 120, 124, 

139, 366-368. 

Ref. 21, pp.29-

32; Ref. 51, pp. 

2, 5, 9, 17; Ref. 

52, pp. 15-16; 

Ref. 61, pp. 1, 

3, 5, 8, 9, 14, 

222-224 

- - 

** Sample IDs ending in 12 represent samples collected from 6-12 inches (Ref. 5, p. 10; Ref. 21, p. 11). 

Bold Indicates background value selected for this document / mg/kg 

CRSC Cancer Risk Screening Concentration 

RDSC Reference Dose Screening Concentration 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 53 - MTD093291599

J The associated numerical value is an estimated quantity and is the approximate concentration of the analyte in the sample. 

J+ The associated numerical value is an estimated quantity, but the result may be biased high. 

( ) Validated value prior to adjustment as per EPA Fact Sheet “Using Qualified Data to Document an Observed Release and 

Observed Contamination” (Ref. 43, 18 pages). 

mg/kg milligrams per kilogram

Area of Observed Contamination 

Surface Soil, <2 ft. bgs, all samples listed below show at least one concentration of arsenic, cadmium, or lead 

greater than 3 times background (Ref. 1, Table 2-3, p. 51589). All of the residential soil samples listed in the 

table were collected as grab samples from either the 0 to 2 “or the 6 to 12” horizon below ground surface 

using stainless steel hand augers, bowls, and spoons to collect the sample. All non-disposable sampling 

equipment was decontaminated between sample locations. The samples were collected into a stainless steel 

bowl before being transferred into a 12X12 inch seal top poly bag or directly into 12X12-inch seal top poly 

bags labeled with the sample identifier. All samples were collected within 200 feet of the residence on the 

property (Ref. 5, p. 11; Ref. 21, p. 11-12). Qualified analytical data has been corrected as per the EPA 

Guidance “Using Qualified Data to Document an Observed Release and Observed Contamination” (Ref. 43, 

pp. 4 and 13). 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

R11ST0111FY02 MH26N3 

111 11th Street 07/11/2008 73.2 3 261 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p. 1; Rp. 5; RefRef. 63, 

R12ST0106FY12 MH26N4 

106 12th Street 07/11/2008 30.6 2.7 98.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p.5; R27, 31, 3Ref. 63, 

R12ST0121FY112 MH26N5 

121 12th Street 07/11/2008 215 13 706 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 23, p. 17; 62, 283. 

R13ST0112BY02 MH26N6 

112 13th Street 07/10/2008 47.3 44.9 562 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 23, p. 12; 62, 283. 

R13ST0117FY02 MH26N7 

117 13th Street 07/11/2008 21.4 69.1 439 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.10; 27, 31, 37; Ref. 143, 283

R13ST0121F112 MH1H38 

121 13th Street 08/11/2007 (66.8 J) 

38.4

(2.5 J+) 

1.8 

(754 J) 

523.6 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi

HRS Documentation Record March 2010 - 54 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

9, 10, 129, 17, 64

R13ST0123FY02 MH26N9 

123 13th Street 07/12/2008 16.5 9.2 432 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.14; 31, 32, 463, pp. 1

R13ST0127FY12 MH26P0 

127 13th Street 07/12/2008 36.3 7.8 340 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.15; 31, 32, 463, pp. 1

R14ST0122F102 MH1H39 

122 14th Street 08/11/2007 (24.2 J) 

13.9 

111 (607 J) 

421.5 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi10, 12, 21, 3, 5, 8

R16ST0121BY12 MH26P1 

121 16th Street 07/14/2008 67.8 14.5 333 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.17; 3B, 3G, Ref. 61, 182, 184

R15ST0215B102 MH1H40 

215 15th Street 08/08/2007 (18 J) 

10.3 

11.6 (553 J) 

384.0 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi10, 12, 219, 64, 2

R15ST0307F112 MH1H41 

307 15th Street 08/08/2007 (39.8 J) 

22.9 

(2.2 J +) 

1.6 

(789 J) 

547.9 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi

HRS Documentation Record March 2010 - 55 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

9, 10, 129, 20, 64

R16ST0128F112 MH1H43 

128 16th Street 08/11/2007 (34.5 J) 

19.8 

(2.3 J+) 

1.6 

163 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi52, 53, 513, 64, 1

R17ST0122F112 MH1H44 

122 17th Street 08/11/2007 (60.1 J) 

34.5

(27 J) 

19.2 

967 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi54, 56, 664, 115-

R17ST0125F112 MH1H45 

125 17th Street 08/12/2007 (43.5 J) 

25 

(6.9 J) 

4.9 

162 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi54, 56, 664, 118-

R20ST0118BY12 MH26P3 

118 20th Street 07/10/2008 22.8 9.4 319 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.22; 3B, 3F, 314; Ref. 180, 182 

R21ST0328FY12 MH26P4 

328 21st Street 07/15/2008 72.4 2.5 86.2 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.25; 3C, 3F, 318; Ref. 180, 182

R21ST0520FY12 MH26P5 

520 21st Street 07/15/2008 47.5 2.6 90.1 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Ref. 2, Ref. 5, A

HRS Documentation Record March 2010 - 56 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

Pb = 1/0.25/NA D, p.30; 

3B, 3C, 2, p. 19; 78, 92. 

R21ST0625F112 MH1H47 

625 21st Street 08/10/2007 43.6 2.7 124 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 125Ref. 60, 458. 

R21ST0641S112 MH1H48 

641 21st Street 08/10/2007 38.4 2.8 199 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 1256, 10, 28

R22ST0114B112 MH1H50 

114 22nd Street 08/09/2007 84.4 27.3 397 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi120, 12510, 30, 6

R22ST0118F102 MH1H52 

118 22nd Street 08/09/2007 (22.4 J) 

12.9 

25.8 (519 J) 

399.2 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1210, 23, 6

R22ST0613B112 MH1H54 

613 22nd Street 08/10/2007 (39.8 J) 

22.9 

7.8 (272 J) 

209.2 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 12pp. 1, 3420-422 

HRS Documentation Record March 2010 - 57 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

R22ST0633B112 MH1H55 

633 22nd Street 08/10/2007 (53.1 J) 

33.2

2.9 (290 J) 

223.1 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1211, 26, 6

R22ST0641B112 MH2174 

641 22nd Street 08/09/2007 (88.8 J) 

55.5 

3.6 (223 J) 

171.5 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1211, 27, 6

RCHAV1820BY12 MH26Q0 

1820 Chicago Ave. 

07/13/2008 50.9 2.7 89.4 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, p23-24, App. 2, 3B64, pp. 185, 189

RCOAV1508S112 MH2176 

1508 Colorado Avenue 

08/10/2007 (53.1 J) 

33.2

(3 J+) 

2.1 

179 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 53, 8, 10, 

RCOAV1702BY12 MH26Q2 

1702 Colorado Avenue 

07/12/2008 29.3 1.6 76.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.37; 3B, 3C, book 2, p51, 87. 

RCOAV1711B102 MH2177 

1711 Colorado Avenue 

08/10/2007 (23.9 J) 

13.7 

(3.9 J) 

2.8 

94.6 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5

HRS Documentation Record March 2010 - 58 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

8, 10, 17

RCOAV1903B112 MH2179 

1903 Colorado Avenue 

08/10/2007 (63.8 J) 

39.9

(13.2 J) 

9.4 

866 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 58, 10, 18

RCOAV1904B112 MH2180 

1904 Colorado Avenue 

08/09/2007 (32.9 J) 

18.9 

(5.5 J) 

3.9 

224 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 58, 10, 19

RCOAV1906B112 MH2181 

1906 Colorado Avenue 

08/09/2007 (35.7 J) 

20.5 

(6.9 J) 

4.9 

216 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 54, Ref. 62, 464 

RCOAV1909BY02 MH26Q3 

1909 Colorado Avenue 

07/13/2008 29.3 13.1 394 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.39; 3B, 3F, 3p. 7; Ref

RCOAV1917VG02 MH2182 

1917 Colorado Avenue 

08/09/2007 (6.8 J) 

3.9 

(3.8 J+) 

2.7 

119 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 21, Appendi49, 52, 53, 8, 11, 

RCOAV1922B112 MH2183 

1922 Colorado Avenue 

08/09/2007 (27.6 J) 

15.9 

(1.8 J+) 

1.3 

68.7 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 53, 61, 3, 8, 1

HRS Documentation Record March 2010 - 59 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

568, 573

RCOAV1923F112 MH2184 

1923 Colorado Avenue 

08/11/2007 35.3 3.8 152 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 179, 560

RCOAV1925F112 MH2185 

1925 Colorado Avenue 

08/12/2007 (29.3 J) 

16.8 

(2.6 J+) 

1.8 

141 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 53, 8, 11, 

RMTAV1518FY02 MH26Q5 

1518 Montana Avenue 

07/15/2008 16.3 24.6 334 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.41; 3B, 3F, 37, 8, 24, 

RMTAV1708VG12 MH26Q7 

1708 Montana Avenue 

07/14/2008 67.3 1.2 75.8 As = 1/0.37/0.43 

Cd = 0.50.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, Appendi27, pp. 20; Ref. 1, 4, 7, 8

RMTAV1716BY12 MH26Q8 

1716 Montana Avenue 

07/09/2008 9 11 536 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.46; 3B, 3F, 3p. 8; Ref

RMTAV1722FY02 MH26R0 

1722 Montana Avenue 

07/10/2008 30.3 3.8 147 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p.48; 

HRS Documentation Record March 2010 - 60 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

3B, 3C, 7, 8, 29, 

RMTAV1901FY12 MH26R1 

1901 Montana Avenue 

07/10/2008 43.4 2.9 148 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, A3; Ref. 263, pp. 1290, 295

RMTAV1908F112 MH2186 

1908 Montana Avenue 

08/09/2007 (50.4 J) 

29 

(2.8 J+) 

2 

119 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 185. 

RMTAV1912F102 MH2187 

1912 Montana Avenue 

08/09/2007 (14.4 J) 

8.3 

(4.8 J) 

3.4 

331 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 5Ref. 62, 188. 

RMTAV1915BY12 MH26R3 

1915 Montana Avenue 

07/13/2008 75 0.5 26.7 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5, AD, p. 5224, 27, 311; Ref. 128. 

RMTAV1924B112 MH2189 

1924 Montana Avenue 

08/10/2007 (55.5 J) 

34.7

(3.6 J+) 

2.6 

112 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi49, 52, 525-26; R192-194

HRS Documentation Record March 2010 - 61 - 
Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

RRBDR2720F102 MH2190 

2720 Rainbow Dam Road 

08/11/2007 (71.9 J) 

44.9

(4.2 J) 

3 

141 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi52, 54, 529, 64, 1

RRVAV2118B112 MH2191 

2118 River Avenue 

08/10/2007 (85.2 J) 

53.3 

(4.7 J) 

3.3 

1,650 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, Ref. 62, 200, 465

RSMAV1605B112 MH2192 

1605 Smelter Avenue 

08/11/2007 (45.1 J) 

25.9 

(3.2 J+) 

2.3 

137 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, 78; Ref. 201-203

RSMAV1624B112 MH2193 

1624 Smelter Avenue 

08/11/2007 (72.6 J) 

45.4

(2.7 J+) 

1.9 

280 As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Ref. 51, 79.Ref. 213-215

RSMAV1917FY12 MH26R5 

1917 Smelter Avenue 

07/14/2008 42.7 3.8 167 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. Appendi27, pp. 2book 2, p25, 62, 1

RSMAV2021SY12 MH26R6 

2021 Smelter Avenue 

07/14/2008 53.1 13.5 351 As = 1/0.37/0.43 

Cd = 0.5/0.040/39 

Pb = 1/0.25/NA 

Ref. 2, Ref. 5. AD, p.57; 27, 31, 37B, 26, 5

HRS Documentation Record March 2010 - 62 - 
HRS Documentation Record 

March 2010 - 63 - 

Sample ID Address Sample Date 

Arsenic 

(As) 

(mg/kg) 

Cadmium(Cd) 

(mg/kg) 

Lead 

(Pb) 

(mg/kg) 

CRDL/MDL/SCDM

 (mg/kg) 

RSMAV2233F102 MH2194 

2233 Smelter Avenue 

08/12/2007 (15 J) 

8.6 

6.7 (131 J) 

100.8 

As = 1/0.49/0.43 

Cd = 0.5/0.20/39 

Pb = 1/0.49/NA 

Ref. 2, Ref. 21, Appendi8, 10, 1212, 30, 6

J The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in J+ The analyte was positively identified; the associated numerical value is the approximate concentration of the analyte in ( ) Value prior to correction as per EPA guidance 9285-7-14FS “Using Qualified Data to Document an Observed Release and 

43, pp. 2 and 13). 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 64 - MTD093291599 

Attribution

In August of 2007 residential soil samples from the 0-2 inches below ground surface and the 6-12 inch below 

ground surface horizons were collected by START from 33 residential properties in Black Eagle, Montana 

(Ref. 21, pp. 13-14, 18). 

In July 2008, residential soil samples from the 0-2 inches below ground surface and the 6-12 inch below 

ground surface horizons were collected by START from 59 residential properties in Black Eagle, Montana. A 

minimum of four soil samples were collected from each residential property. An additional 20 soil samples 

were collected from the public playground and baseball fields located on the south side of Black Eagle, 

Montana (Ref. 5, p. 1, 10). All soil samples were analyzed in the field using an X-Ray Fluorescence 

Spectrometer (XRF) (Ref 5, p. 1). Thirty-nine soil samples were selected after reviewing the field XRF data 

and were submitted to a Contract Laboratory Program (CLP) laboratory for collaborative analysis. A total of 

60 soil samples, from both Great Falls and Black Eagle, in 2007 and thirty-nine soil samples from Black 

Eagle in 2008 were sent for collaborative analysis by analytical method EPA CLP ILM05.4 (Ref. 5, p. 1; Ref. 

21, p.1; Ref. 60, p. 1; Ref. 61, p. 1, Ref., 62, p. 1, Ref. 63, p. 1, Ref. 64, p. 1). 

Aerial deposition of contaminants emanating from the smelter smoke stacks between 1893 and 1972 is the 

most likely mechanism of contaminant transport to the community of Black Eagle’s residential soils (Ref. 8, 

p. 6A; Ref. 9, p. 15). The 506 foot tall Big Stack was designed to eject a volume of 1,575,000 cubic feet of 

air per minute at a velocity of 450 feet per minute, a sufficient volume and rate to entrain and remove from the 

smelter all the gases and dust generated during the smelting process (Ref. 9, p. 20). ). An internal Anaconda 

Copper Company Memorandum from 1951 stated that approximately 15.04 pounds of arsenic passed out of 

the stack every 24 hours (Ref. 33, p. 1). 

The wind direction in the Great Falls, Montana area is usually from the southwest, particularly in the months 

of October through March. Wind data collected at the Great Falls International Airport, approximately 5 

miles southwest of the community of Black Eagle shows that during March, April, and May the winds can 

blow from the northwest or northeast more than twenty percent of the time and that in the summer months of 

June, July, and August wind direction over Black Eagle is from the northeast or east more than 20 percent of 

the time 

(Ref. 30, pp. 2-13). A south facing aerial photo published by the Great Falls Tribune in 2002 shows smoke 

from the 506 foot tall stack wafting westward across the community of Black Eagle (Ref. 29, p. 8A). 

The former Montana Silver Smelter site is located on the south bank of the Missouri River in Giant Springs 

State Park, approximately 2.85 miles east-northeast of the 15th Street Bridge (Ref. 4, 2 pages). The Montana 

Silver Smelter was constructed in 1888 by Great Falls city father, Paris Gibson (Ref. 56, p. 2). The smelter 

had two small stacks. Many of the structures at Giant Springs State Park and Giant Springs State Fish 

Hatchery were built on mineral processing wastes that contained extremely high levels of arsenic and lead. 

This property was cleaned up by the Montana Mine Waste Cleanup Bureau’s Abandoned Mine Lands 

Program in 2004 (Ref. 57, pp. 9-11). 

The Montana Refining Company is located immediately west of the unincorporated community of Black 

Eagle on the north bank of the Missouri River at 1900 10th Street, NE, Great Falls, Montana (Ref. 50). The 

Montana Refining Company produces various grades of gasoline, diesel, jet fuel, distillates, and high grade 

asphalt products (Ref. 65, 1 page.). The facility has an operable capacity of 9,500 barrels per calendar day 

ranking the facility as number 132 of the 143 U.S. Refineries (Ref. 66, p. 4). 

The former Montana Silver Smelter and the Montana Refining Company may have contributed contamination 

to the community. However, as documented above, the ACM Smelter and Refinery facility also contributed 

contamination; therefore, the contamination in Black Eagle is at least partially attributable to ACM Smelter 

and Refinery. 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 65 - MTD093291599 

Area of Contamination Hazardous Waste Quantity

- Hazardous Constituent Quantity: 

Are the data complete for Hazardous constituent quantity for this area? NO 

Hazardous Constituent Quantity Assigned Value: NA 

- Hazardous Wastestream Quantity: 

Are the data complete for Hazardous Wastestream quantity for this area? NO 

Sum (pounds): NA 

Wastestream Quantity/5,000 (Ref. 1, Table 5-2): NA 

 

Hazardous Wastestream Quantity Assigned Value: NA 

 

- Volume: 

Are the data complete for Hazardous volume for this area? NO 

Sum (yd3

/gal): NA 

Equation for Assigning Value (Ref. 1, Table 5-2): NA 

Volume Assigned Value: 0 

- Area: A 

Description

Arsenic and cadmium results from soil samples collected in the summers of 2007 and 2008 that are 

documented to be at Level I concentrations delineate an area of approximately 1,926,569 square feet (ft2

) 

(Ref. 1, Sections 2.5.1, 2.5.2, 5.1.3.1; Ref. 22, p. 2). The area covered by streets within the area was 

calculated to be 322,000 square feet (Ref. 25, p. 1). It was calculated that an average of 31 percent of each lot 

in Black Eagle, Montana is covered by a structure or pavement or 69 percent of the average property is open 

soil (Ref. 26, p. 3). 

Calculation

(1,926,569 ft2 of contaminated soil) – (322,000 ft2 of pavement) = 1,604,569 ft. (1,604,569 ft2

)(0.69 open soil) 

= 1,107,152.61ft2

Source Type Units (ft2) References 

Contaminated Surface Soils 1,107,152.61 Ref. 22, p. 2; Ref. 25, p. 1; Ref. 

26, p. 3 

By following the stated procedure outlined in Sections 2.4.2 and 5.1.2.2 and Table 5-2 of the HRS (Ref. 1, p. 

51647, Table 5.2), the area value is assigned as follows: 1,107,152.61(ft2

)/34,000= 32.5633 

Area Assigned Value: 32.5633 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 66 - MTD093291599 

 5.1 RESIDENT POPULATION THREAT

Observed contamination samples were selected from the Analytical Results Reports for the 2007 

CERCLA Site Assessment and from the 2008 Expanded Site Investigation to establish laboratory verified 

concentrations of arsenic lead, and cadmium, as well as sample ID, street address, property owner, and the 

date each sample was collected (Ref. 21, pp. 29-32; Ref. 5, pp. 28-31). All samples listed in Section 5.0.1 

of this HRS documentation record were collected within 200 feet of the residence (Ref. 21, p. 1; Ref. 5, 

pp. 4 and 5). Analysis of sample R12ST0121FY12 (MH26N5) collected on July 11, 2008, with an 

arsenic concentration of 215 mg/kg, a cadmium concentration of 13 mg/kg, and a lead concentration of 

706 mg/kg in surface soils from a collection depth < 2 feet bgs documents the resident population threat 

(Ref. 5, Appendix C, p. 49. Appendix D, p.8; Ref. 24, p. 1; Ref. 36, book 3, p. 17; Ref. 63 p. 15) 

5.1.1 LIKELIHOOD OF EXPOSURE

The presence of arsenic, cadmium, and lead contamination in concentrations meeting observed contamination 

requirements on residential property within 200 feet of the primary dwelling establishes a resident population 

threat for the site (Ref.1, Section 5.1, p. 51646). The location of each sample was noted on the property 

sketch of the Residential Soil Sampling Log, which documents that all samples were collected on the property 

and within 200 feet of the residence (Ref. 5, Appendix D; Ref. 21, Appendix D). In addition a digital 

download of a property plat was obtained from the Cascade County uniquely identifying each parcel of 

property (Ref. 37, p. 1). 

Resident Population Threat Likelihood of 

Exposure Factor Category Value: 550 

5.1.2 WASTE CHARACTERISTICS

5.1.2.1 Toxicity

Hazardous Substance Toxicity Factor Value Reference 

Arsenic, Cadmium, and Lead 10,000 Ref. 2, pp. BI-1, BI-2, BI-8 

Toxicity Factor Value: 10,000 

5.1.2.2 Hazardous Waste Quantity 

Because Level I contamination has been documented, but the hazardous constituent quantity is not adequately 

determined for the area of observed contamination the final assigned waste quantity factor value is 10 (see 

Section 5.0.1 of this HRS documentation record; Ref. 1, Section 2.4.2.2.p. 51592, Section 2.4.2.2). 

Area Assigned Value: 1 

Area Letter Source Type AOC Hazardous Waste Quantity 

A Contaminated Soil 32.5633 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 67 - MTD093291599 

Equation for Assigning Value (Ref. 1, p. 51647, Table 5-2; p. 51591, Section 2.4.2.2) 

Since 1 < 32.5633 < 100 the hazardous waste quantity factor value assigned from Table 2-6 is 1. However, as 

the hazardous constituent quantity is not adequately determined, a value of 10 is assigned for this AOC as per 

HRS, Section 2.4.2.2 (Ref. 1, Section 2.4.2.2). 

Hazardous Waste Quantity Factor Value: 10 

(Ref. 1, Section 2.4.2.2) 

5.1.2.3 Calculation of Waste Characteristics Factor Category Value

Toxicity Factor Value: 10,000 

Hazardous Waste Quantity Factor Value: 10 

Toxicity Factor Value x Hazardous Waste Quantity Factor Value: 100,000 

Waste Characteristics Factor Category Value: 18 

(Ref. 1, p. 51592, Table 2-7) 

5.1.3 TARGETS

5.1.3.1 Resident Individual

Level of Contamination (Level I/Level II): Level I 

There are 8 residential soil samples that exhibit Level I arsenic or cadmium contamination within the 

unincorporated community of Black Eagle, Montana (see Section 5.0.1 of this HRS documentation record). 

These samples delineate an area of observed soil contamination and document the presence of Level I soil 

contamination at each of the eight residences. All residences within the area of observed soil contamination 

are subject to actual contamination. These samples were all collected on the resident individual’s property 

and within 200 linear feet of the residence; therefore a resident individual factor of 50 is assigned (Ref. 5, pp. 

4 & 5). (Ref.1, Section 5.1.3.1, p. 51647; 8; Ref. 5, p.10, Appendix D, p. 8) 

Resident Individual Factor Value: 50 

5.1.3.2 Resident Population

5.1.3.2.1 Level I Concentrations

Area Letter Sample ID Number of 

Residences 

County 

Multiplier 

No. of 

Residents 

A See Section 5.0.1 of this 

HRS documentation record 

8 2.41 19.28 

Sum of individuals subject to Level I concentrations: 19.28 

Sum of individuals subject to Level I concentrations x 10: 192.8 

Analysis from residential surface soil samples collected from the community of Black Eagle indicate the 

presence of arsenic and/or cadmium at levels three times the background concentration or greater, and 

exceeding the applicable health based benchmark at 8 residences (Ref. 2, pp. BII-I and BII-2). U.S. 

Department of Commerce, Bureau of Census data (Ref. 28, p. 1) indicates that there is an average of 2.41 

individuals per residence in Cascade County, Montana. Eight residences, with an average of 2.41 residents 
HRS Documentation Record ACM Smelter and Refinery 

March 2010 - 68 - MTD093291599 

per household, result in a total of 19.28 individuals subject to Level I arsenic or cadmium concentrations. 

Since these individuals are subject to Level I contamination, the appropriate factor value is determined by 

summing the individuals subject to Level I contamination and multiplying by 10 (Ref. 1, Section 5.1.3.2.1, p. 

51647) yielding a total factor value of 192.8 

Level I Concentrations Factor Value: 192.8 

5.1.3.2.2 Level II Concentrations

Properties that are wholly or partially included within the zone defined by arsenic and cadmium 

contamination at Level I concentrations include approximately 178 residences that are within 200 feet of the 

zone of contamination (Ref. 22, p. 2; Ref. 37, p. 1). Eight of these residences have documented Level I 

contamination within 200 feet of the residence leaving approximately 170 residences exposed to Level II 

contamination (Ref. 22. page 2; Ref. 37, p. 1). 170 residences with a county average of 2.41 individuals per 

residence results in 409.7 people being exposed to Level II Concentrations (Ref. 28, p. 1) 

Sum of individuals subject to Level II contaminations: 409.7 

Level II Concentrations Factor Value: 409.7 

5.1.3.3 Workers

Total workers were not scored (NS) 

Workers Factor Value: NS 

5.1.3.4 Resources

Resource Description: There is no commercial agriculture, silviculture, or commercial livestock production 

or grazing within the area of observed contamination. 

Resources Factor Value: 0 

5.1.3.5 Terrestrial Sensitive Environments

Sensitive Environment Description: There are no terrestrial sensitive environments identified within the area 

of observed contamination. 

Terrestrial Sensitive Environments Factor Value: 0 

5.2 NEARBY POPULATION THREAT 

Nearby population threat was not scored 

 Nearby Population Threat Factor Value: NS