Hazard Ranking System (Hrs) Documentation Record Cover Sheet

HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD COVER SHEET

Name of Site: Ore Knob Mine

EPA ID No.: NCN000409895

Contact Persons

Documentation Record: Jennifer Wendel, National Priorities List Coordinator U.S. Environmental Protection Agency, Region 4 61 Forsyth Street, S.W., 11th Floor Atlanta, Georgia 30303 (404) 562-8799

Pathways, Components, or Threats Not Scored

The ground water migration, soil exposure, and air migration pathways were not scored in this Hazard Ranking System (HRS) documentation record because they are not expected to significantly contribute to the overall score.

Ground Water Migration Pathway: Actual contamination at Level I concentrations is present in two private drinking water wells that serve about 5 people and actual contamination at Level II concentrations is present in three private drinking water wells that serve about 9 people (Refs. 2, p. BII-8; 5, Appendix A, Table A.5-2; 54). Additional private wells may be located within the 4-mile radius of Ore Knob Mine. Some residents within a 4-mile radius of Ore Knob Mine obtain drinking water from a surface water intake maintained by the City of Jefferson (Ref. 21).

Soil Exposure Pathway: About 128 people reside within 1 mile of Ore Knob Mine (Ref. 53, p. 1). The surrounding area is very rural, largely undeveloped, and sparsely populated. About 6 residences are located in the vicinity of areas formerly mined for copper (Ref. 5, Figure 3-5). Soil samples were collected on three residential properties (Ref. 5, Table 3-5, Appendix A, Table A.5-1). Metals (cadmium, chromium, zinc, etc.) were detected at levels both above and below the levels detected in background samples for the site.

Air Migration Pathway: The 2007 integrated assessment focused on the collection of surface water, sediment, and soil in formerly mined areas and residential properties; waste samples from on-site sources; seeps emanating from the main tailings pile; and ground water samples (Ref. 5, p. 1, Tables 3-1 through 3-6). The residential population within 4 radial miles of the Ore Knob property is about 1,328 people (Ref. 53, p. 1). Minimal wetlands are located within 4 radial miles of Ore Knob Mine (Ref. 44). HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD

Name of Site: Ore Knob Mine

EPA Region: 4

Date Prepared: April 2009

Street Address of Site*: Near the intersection of Ore Knob Mine Road and Little Peak Creek Road, about 0.5 mine north of North Carolina Highway 88 (Refs. 3; 4, p. 2).

City, County, State, Zip Code: Jefferson, Ashe County, North Carolina, 28640

General Location in the State: 12 miles south of the Virginia state line; 22 miles east of the Tennessee border; about 10.6 miles east of the town of Jefferson, North Carolina; and about 4.5 miles west of the town of Laurel Springs, North Carolina (Ref. 4)

Topographic Map: Laurel Springs, North Carolina, 1971

Latitude: 36.41° (36° 24' 36.04") north Longitude: -81.3246° (81° 19’ 28.58”) west

The coordinates above for Ore Knob Mine (Ore Knob) were measured from the centerline of the main tailings pile (Source 1) dam (Refs. 4, pp. 1, 2, 3, 4; 5, Figure 3-4)

* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general site location. The information represents one or more locations the U.S. Environmental Protection Agency (EPA) considers to be part of the site based on the screening information EPA used to evaluate the site for the National Priorities List. EPA determines national priorities sites from 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 an area 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 represent the initial determination that a certain area may need to be addressed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Accordingly, EPA contemplates that the preliminary description of site boundaries at the time of scoring will be refined as more information is developed concerning the location of contamination.

Migration Pathway Pathway Score Ground Water Migration Pathway NS Surface Water Pathway 100.00 Soil Exposure Pathway NS Air Migration Pathway NS HRS SITE SCORE 50.00

Note:

NS Not scored

WORKSHEET FOR COMPUTING HRS SITE SCORE

S pathway S2 pathway

Ground Water Migration Pathway Score (Sgw) NS NS

Surface Water Migration Pathway Score (Ssw) 100 10,000

Soil Exposure Pathway Score (Ss) NS NS

Air Migration Pathway Score (Sa) NS NS 2 2 2 2 Sgw + Ssw + Ss + Sa 10,000 2 2 2 2 (Sgw + Ssw + Ss + Sa )/4 2,500 2 2 2 2 / (Sgw + Ssw + Ss + Sa )/4 50.00

Note:

NS = Not scored

Table 4-1 –Surface Water Overland/Flood Migration Component Scoresheet

Factor Categories and Factors Maximum Value Value Assigned Drinking Water Threat Likelihood of Release: 1. Observed Release 550 550 2. Potential to Release by Overland Flow: 2a. Containment 10 2b. Runoff 25 2c. Distance to Surface Water 25 2d. Potential to Release by Overland Flow [lines 500 2a(2b + 2c)] 3.Potential to Release by Flood: 3a. Containment (Flood) 10 3b. Flood Frequency 50 3c. Potential to Release by Flood (lines 3a x 3b) 500 4. Potential to Release (lines 2d + 3c, subject to a 500 maximum of 500) 5. Likelihood of Release (higher of lines 1 and 4) 550 550 Waste Characteristics: 6. Toxicity/Persistence (a) 10,000 7. Hazardous Waste Quantity (a) 10,000 8. Waste Characteristics 100 100 Targets: 9. Nearest Intake 50 10. Population: 10a. Level I Concentrations (b) 10b. Level II Concentrations (b) 10c. Potential Contamination (b) 10d. Population (lines 10a + 10b + 10c) (b) 11. Resources 5 5 12. Targets (lines 9 + 10d + 11) (b) 5 Drinking Water Threat Score: 13. Drinking Water Threat Score [(lines 100 3.33 5x8x12)/82,500, subject to a maximum of 100] Human Food Chain Threat Likelihood of Release: 14. Likelihood of Release (same value as line 5) 550 550 Waste Characteristics: 15. Toxicity/Persistence/Bioaccumulation (a) 500,000,000 16. Hazardous Waste Quantity (a) 10,000 17. Waste Characteristics 1,000 1,000 Targets: 18. Food Chain Individual 50 20

Table 4-1 –Surface Water Migration Pathway Scoresheet (Continued)

Factor Categories and Factors Maximum Value Value Assigned 19. Population 19a. Level I Concentrations (b) 19b. Level II Concentrations (b) 19c. Potential Human Food Chain (b) Contamination 19d. Population (lines 19a + 19b + 19c) (b) 20. Targets (lines 18 + 19d) (b) 20 Human Food Chain Threat Score: 21. Human Food Chain Threat Score [(lines 100 100 14x17x20)/82,500, subject to maximum of 100] Environmental Threat Likelihood of Release: 22. Likelihood of Release (same value as line 5) 550 550 Waste Characteristics: 23. Ecosystem Toxicity/Persistence/Bioaccumulation (a) 500,000,000 24. Hazardous Waste Quantity (a) 10,000 25. Waste Characteristics 1,000 1,000 Targets: 26. Sensitive Environments 26a. Level I Concentrations (b) 26b. Level II Concentrations (b) 50 26c. Potential Contamination (b) 26d. Sensitive Environments (lines 26a + 26b + (b) 50 26c) 27. Targets (value from line 26d) (b) 50 Environmental Threat Score: 28. Environmental Threat Score [(lines 60 60 22x25x27)/82,500 subject to a maximum of 60] Surface Water Overland/Flood Migration Component Score for a Watershed 29. Watershed Scorec (lines 13+21+28, subject to a 100 100 maximum of 100) Surface Water Overland/Flood Migration Component Score c 30. Component Score (Ssw) (highest score from line 29 for all watersheds 100 100 evaluated)

Notes: a Maximum value applies to waste characteristics category b Maximum value not applicable c Do not round to nearest integer

Former Freshwater Pond Pond Freshwater Former 1950's Mine Mine 1950's and Mill Mill and Operations Area Roaster / Smelter Wastes Smelter / Roaster Historic Mine Historic 19th Century Century 19th Main Tailings Main Pile Pile NORTH CAROLINA TOPOGRAPHIC QUADRANGLE, 1971 QUADRANGLE, TOPOGRAPHIC ASHE COUNTY, ASHE COUNTY, United States Environmental Protection Agency

OPERATIONAL AREAS OPERATIONAL USGS, LAUREL SPRINGS, NC SPRINGS, USGS, LAUREL TDD No.TTEMI-05-003-0033

NORTH CAROLINA NORTH CAROLINA ORE KNOB MINE MINE KNOB ORE LAUREL SPRINGS,

MAP SOURCE: MAP SOURCE: ASHE COUNTY, COUNTY, ASHE FIGURE 1 FIGURE I

1:24,000 1,000 2 , 0 0 Feet Feet 0

2008-10-14 \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Site Location Maps\ORE KNOB SITE LOC MAP 10-13-08.mxd TTEMI-KY dale.vonbusch

2009-1-30 \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source No 1 Maps\ORE KNOB SOURCE 1 8x11 1-30-09.mxd TTEMI-KY dale.vonbusch dale.vonbusch TTEMI-KY 1-30-09.mxd 8x11 1 SOURCE KNOB Maps\ORE 1 No \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source 2009-1-30 I Feet Feet 0 0 3

FIGURE 2 150 ASHE COUNTY, ORE KNOB MINE SOURCE NO.SOURCE 1: 1:3,600 1:3,600 LAUREL SPRINGS,LAUREL CAROLINANORTH Probable Point of Entry Seep Location Waste Material Pipe Drainage Basin Settling Pile Under Pipe of Path Inferred Source No. 1: Main Tailings Pile Tailings Dam Face Settling Basin Perennial Pond Road

MAIN TAILINGS PILE !

No.TTEMI-05-003-0033 TDD

h United States Environmental Protection Agency Agency Protection Environmental States United # V X W !

Note: Knob - Ore OK Source: North Carolina, County, Ashe Photograph: Aerial 2004. Report, Inspection Site Expanded Map: Final Base 2008 September Veatch, & Black 3-4, 2-4, Figure 0 Sampling StationsSampling Drainage Pipes Features Mine Water Surface FeaturesOther LEGEND !

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! !

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!E Adits !E Historic Features

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XW OK553 Surface Water

%2 > & Perennial OK500 Other Features Road

Note:

OK513 OK - Ore Knob Source: OK520 Aerial Photograph: Ashe County, North Carolina, 2004.

%2 T" Base Map: Final Expanded Site Inspection Report, > & > & OK502 Figure 3-2, Black & Veatch, September 2008. > &

T" OK514 USACE Huntington District. US Bureau of Mines, 1948.

T" 0150 300

"T Feet 1:3,600 I

T" Historic Mine United States Environmental Protection Agency

> & ORE KNOB MINE

OK511 > & LAUREL SPRINGS, OK512 ASHE COUNTY, NORTH CAROLINA

%2 TDD No.TTEMI-05-003-0033 OK501 FIGURE 3 "T SOURCE NO. 2: MULTIPLE AREAS OF CONTAMINATED SOIL IN THE 19TH CENTURY OPERATIONS AREA

2009-2-18 2009-2-18 No 2 Maps\ORE KNOB 2-18-09.mxd 2 8x11 TTEMI-KYSOURCE \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source dale.vonbusch LEGEND

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XW Sampling Stations # Waste V

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XW PPE 3 Other Features

%2 Estimated Extent of Source No. 3 Road OK500 Note: OK - Ore Knob Source: Aerial Photograph: Ashe County, North Carolina, 2004.

Base Map: Final Expanded Site Inspection Report, Figure 3-2, Black & Veatch, September 2008.

"T U.S. Army Corps of Engineers, Ore Knob OK502 Restoration Project, March 2003. T" U.S. Bureau of Mines, Investigation of the Ore Knob Copper Mine, 1948.

T" 0150 300

"T Feet 1:3,600 I

"T United States Environmental Protection Agency

T" ORE KNOB MINE Historic Mine LAUREL SPRINGS, Area ASHE COUNTY, NORTH CAROLINA

%2 TDD No.TTEMI-05-003-0033 OK501 FIGURE 4

"T SOURCE NO. 3: SLAG DUMP WASTE PILE LOCATED IN THE 19TH CENTURY OPERATIONS AREA

2009-1-30 2009-1-30 No 3 Maps\ORE KNOB 1-30-09.mxd 3 8x11 SOURCE TTEMI-KY \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source dale.vonbusch

k k LEGEND

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k k

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e P

V Waste

e e

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%2 Background L Mine Features

XW Former 1950's Mine and Mill Area

"T Former Mine Shafts Vein Outcrop Source No. 4 Former Freshwater Tailings Pile in the Former OK454 1950s Mine and Mill Area Pond # Surface Water

V Estimated Extent Intermittent of Source No. 4 Perennial OK453 Other Features OK452 #

V # Road

V Note: OK - Ore Knob Source:

"T Aerial Photograph: Ashe County, North Carolina, 2004. Base Map: Final Expanded Site Inspection Report, Figure 3-3, Black & Veatch, September 2008. “U.S. Bureau of Mines, Investigation of the Ore Knob Copper Mine, 1948.

0150 300

%2 Feet OK400 1:3,600 I

United States Environmental Protection Agency

"T Former 1950s %2 ORE KNOB MINE Mine and Mill Area OK401 LAUREL SPRINGS, ASHE COUNTY,

%2 NORTH CAROLINA OK402 TDD No.TTEMI-05-003-0033

FIGURE 5 SOURCE No. 4: TAILINGS PILE IN THE FORMER 1950s MINE AND MILL AREA

2009-1-30 2009-1-30 No 4 Maps\ORE KNOB 1-30-09.mxd 4 8x11 SOURCE TTEMI-KY \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source dale.vonbusch

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k k Sampling Stations

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> Soil &

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%2 Background

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> & Other Features Road Note: OK424 OK - Ore Knob Source: > & Aerial Photograph: Ashe County, North Carolina,

"T 2004.

Base Map: Final Expanded Site Inspection Report, Figure 3-3, Black & Veatch, September 2008. OK417 U.S. Army Corps of Engineers, Ore Knob Restoration Project, March 2003.

U.S. Bureau of Mines, Investigation of the >

OK414 &

> Ore Knob Copper Mine, 1948. &

OK413 0150 300

%2 OK400 Feet > & OK415 OK416 1:3,600 I >

& > &

"T OK412

United States Environmental Protection Agency > & >

"T & OK411

%2 Former 1950s ORE KNOB MINE Mine and Mill Area LAUREL SPRINGS, OK401 ASHE COUNTY,

%2 NORTH CAROLINA TDD No.TTEMI-05-003-0033 OK402

FIGURE 6 SOURCE No. 5: MULTIPLE AREAS OF CONTAMINATED SOIL IN THE FORMER 1950s MINE AND MILL AREA

2009-1-30 2009-1-30 No 5 Maps\ORE KNOB 1-30-09.mxd 5 8x11 SOURCE TTEMI-KY \GIS_Workspace\TTEMI-05-003-0033_Ore_Knob_Mine\Figures\GIS\MXDs\Source dale.vonbusch REFERENCES

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62. Tetra Tech. Project Note to File Regarding Current Activities at Ore Knob Mine. Brian Malone, Environmental Scientist. February 19, 2009. 1 Page.

SITE DESCRIPTION

The Ore Knob Mine (Ore Knob) is located at the intersection of Ore Knob Road and Little Peak Creek Road, north of North Carolina Highway 88 (Refs. 3; 4, pp. 2). The location of Ore Knob is about 10.6 miles east of Jefferson, North Carolina and about 4.5 miles west of Laurel Springs, North Carolina (Ref. 4, pp. 5, 6). Specifically, the geographic coordinates for Ore Knob, as measured from centerline of the main tailings pile dam, are latitude 36.41° (36° 24' 36.04") north and longitude -81.3246° (-81° 19’ 28.58”) west (Refs. 4, pp. 2, 3, 4; 5, Figure 3-4). The U.S. Environmental Protection Agency (EPA) identification number (No.) as recorded in the Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS) database is NCN000409895 (Ref. 43, p. 1). The area surrounding Ore Knob Mine is primarily rural, largely undeveloped, and sparsely populated (Ref. 3). Several residences are located along the perimeter of areas formerly used for mining activities (Ref. 5, p. 77, Figures 2-2 and 3-2). During the 2007 expanded site inspection (ESI) sampling event, industrial activities (an operating sawmill) were observed on portions of the Ore Knob property where contaminated soil and mine wastes are present (Refs. 59, pp. 2, 4, 6, 8, 10; 62). Some of these activities included the use of heavy equipment and grading machines which can potentially excavate these contaminants. Recreational use of portions of the Ore Knob property is also known to occur (Ref. 5, p. 77). During the ESI sampling event, the main tailings pile was observed to be used as a recreational camping site and for off-road vehicle use (Refs. 49, p. 8; 62). In addition, much of the 19th Century mine and mill (Operations) area is leased for use by a hunting club (Ref. 5, p. 77).

The sources of contamination at Ore Knob include a massive 20-acre tailings pile (Source No. 1), a 2-acre tailings pile (Source No. 4), areas of contaminated soil (Source Nos. 2 and 5), and a slag dump waste pile (Source No. 3) resulting from mining activities (Ref. 25) (See Section 2.2.1 of the HRS documentation record).

Ore Knob Mine consists of two distinct areas where mining activities occurred: the 19th Century Operations Area and the Former 1950s Mine and Mill area (Ref. 5, Figures 2-1 through 2-3). Intermittent mining of copper ore at the Ore Knob Mine occurred in those areas from the 1850s through 1962, with most mining occurring during two main periods of activity: 1873 to 1883 and 1957 to 1962 (Refs. 5, p. 9; 40, p. 44). Interconnected mine shafts are located under the two mining areas (Ref. 5, Figure 2-2; 31, Figure 2). Mining and mineral-related activities at the mine included, concentration, roasting, smelting, and waste management. Wastes generated during mining operations are known to have contaminated surface water and sediment with acid mine drainage (AMD) and heavy metals (Ref. 6). The 20-acre main tailings pile (Source No. 1), areas of contaminated soil (Source No. 2), and slag dump waste pile (Source No. 3) located in the 19th Century Operations Area; and the 2-acre tailings pile (Source No. 4) and the areas of contaminated soil located in the Former 1950s Mine and Mill area (Source 5) all eventually drain to Peak Creek and the South Fork New River, and have overlapping target populations (Refs. 3; 5, Appendix E, p. E-1, E-129, E-165; 25). Also tailings from the Former 1950s Mine and Mill were pumped via a pipeline and disposed of in Source No. 1 located in the 19th Century Operations Area (Refs. 25; 45, pp. 1, 3, 6; 52, p. 4). Sources at Ore Knob are depicted on Figures 2 through 6 of this HRS documentation record and Reference 25.

A description of the operations areas that comprise Ore Knob and the 20-acre main tailings pile is provided below. The operational areas at Ore Knob are presented on Figure 1 of this HRS documentation record.

19th Century Operations Area

The 19th Century Operations Area includes the 20-acre main tailings pile, a series of barren and nearly barren areas (about 5 acres) that comprise waste rock dumps from at least 11 mine shafts, and areas where ore was roasted to drive off sulfur and smelted to recover copper (about 5 acres) (Ref. 5, p. 3, Figure 2-2). The 20-acre main tailings pile (Source No. 1) is located in the northern portion of the 19th Century Operations Area. The tailings pile primarily contains tailings from the 1957 to 1962 operational period, although the upper end may contain residual fines from 19th century roasting and smelting (Refs. 5, Figure

16 Site Description

2-2; 42, p. 6; 52, p. 4). As shown on References 25 and 60, the 20-acre tailings pile is massive and dominates the landscape. An area of contaminated soil (Source No. 2) and slag dump waste pile (Source No. 3) have been identified in this operations area, as documented in Section 2.2.1 of this HRS documentation record. The contaminated soil is associated with waste rock dumps and areas where ore was roasted to drive off sulfur and smelted to recover copper (Ref. 5, p. 3, Figure 2-2 and Figure 2-3; Section 2.2.1 of this HRS documentation record).

Also included in this operational area is a wooded area located between the top of Ore Knob hill and the main tailings pile. The wooded area reportedly shelters five sealed/blocked adits (a type of entrance to an underground mine). Only two adits have been identified. AMD from the adits discharges into a perennial stream, Ore Knob Branch. Ore Knob Branch also receives surface water runoff from the 20-acre tailings pile (Source No. 1), the area of contaminated soil (Source No. 2), and slag pile (Source No. 3) (Ref. 5, p. 3, Figures 2-2 and 3-2). Surface water runoff from Source Nos. 2 and 3 flows to the headwaters Ore Knob Branch. The tributary enters an inlet pipe at the southwestern corner of the 20-acre tailings pile, flows under the main tailings pile, and discharges into a settling basin at the northern end of the main tailings pile. The settling basin discharges into Ore Knob Branch (Refs. 3; 5, Figures 2-4 and 3-4; 25).

A photograph of one of the adits shows that the AMD is bright orange and has stained the soil in the surrounding area (Ref. 5, Appendix E, p. E-2). Also, the roaster areas and the slag dumps in the 19th Century Operations Area are orange (Ref. 5, Appendix E, pp. E-36, E-37, E-38, E-47).

Former 1950s Mine and Mill Area

The Former 1950s Mine and Mill area covers about 15 acres and lies about 0.3 mile west-southwest of the 19th Century Operations Area (Ref. 5, Figures 2-1 and 2-2). The Former 1950s Mine and Mill area operated from about 1957 to 1962 (Refs. 5, p. 3; 40, p. 44). A plan of the Former 1950s Mine and Mill indicates that the features of the mine during operations included an adit, water tanks, two shafts, and several buildings. These buildings were constructed on fill material, which is likely to be mine development (waste) rock derived from sinking the mine shaft for this operation (Ref. 5, p. 3, Appendix E, pp. E-53 through E-71). The vein outcrop and a tailing line are also identified on a map that depicts the plan and sections of the Former 1950s Mine and Mill area (Ref. 52, p. 4). At the time of the 2007 ESI sampling event, the following features were observed: derelict ore bins, concrete mill foundations, a transformer building, and other ruins, as well as an operating sawmill (Ref. 5, p. 3, Figure 2-3). A 2-acre tailings pile (Source No. 4) is located in the northern portion of the Former 1950s Mine and Mill area. This pile contains about 10,000 cubic yards (±20 percent) of tailings from the mill and waste rock, and is now mostly covered with tree-stumps. Areas of contaminated soil (Source No. 5) also are located in the former 1950 Mine and Mill area (see Section 2.2.1 of this HRS documentation record).

A 2-acre former fresh water pond is located northeast of the 2-acre tailings pile (Refs. 5, p. 3, Figure 2-1; 25; 59, pp. 2, 4, 6, 8, 10). The headwaters of Little Peak Creek are immediately upstream of the former freshwater pond wetland (Refs. 5, p. 3, Figure 2-2; 25; 59, pp. 2, 4, 6, 8, 10). Little Peak Creek becomes a perennial stream downstream of this pond. From this location, Little Peak Creek continues downstream for about 2 miles before discharging into Peak Creek. Peak Creek continues in a northern direction to merge with South Fork New River (Refs. 3; 5, p. 3, 4, Figure 2-1). Photographs of seeps from the Former 1950s Mine and Mill area leading to surface water are brilliant orange (Ref. 5, Appendix E, p. E-63).

Main Tailings Pile

The main tailings pile (Source No. 1) is located in the northeast portion of the 19th Century Operations Area and primarily contains tailings from mining operations that occurred from 1957 to 1962, although the upper end may contain residual fines from 19th century roasting and smelting (Refs. 5, Figure 2-2; 42, p. 6). The main tailings pile covers about 20 acres in area (Refs. 3; 5, Figure 2-4; 25). See Figure 2 of this HRS documentation record for a layout of the main tailings pile.

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The main tailings pile (Source No. 1) is also known as the tailings impoundment (Ref. 5, p. 3). Water- saturated tailings from the two operational areas were pumped to the tailings impoundment. The water from the impoundment flowed to an outlet (discharge) pipe located in a dam constructed at the northern end of the impoundment. The pipe discharged to Ore Knob Branch. The tailings impoundment is now known as the main tailings pile. The tailings water has since evaporated, leaving the tailings pile with the dam on the northern end. The main tailings pile dam consists of what appears to be a waste rock “starter dam” that serves as a buttress for the upper dam. The upper dam appears to have been constructed of successive lifts of tailings using the upstream method of construction (Refs. 5, pp. 3, 4, 12; 45, pp. 2, 3; 47, p. 1, Logbook 1, p. 4; 58). The dam is about 70 feet high and 700 feet wide. A photograph of the main tailings pile is shown on Reference 58.

The headwaters of Ore Knob Branch enters the southwestern corner of the main tailings pile and is piped underneath the main tailings pile through a 24-inch pipe that exits at the bottom of the dam face (Refs. 5, pp. 3, 4, Figures 2-4 and 3-4, Appendix E, pp. E-78, E-115; 25; 58). The pipe discharges into a sediment pond that is now full and is no longer able to prevent sediment and other precipitates from continuing down to Ore Knob Branch (Refs. 3; 5, p. 4, Figures 2-4 and 3-4; 25; 58).

The dam has been subjected to severe erosion and water emanates from the dam in several places. The face of the dam is deeply incised and erodes directly into Ore Knob Branch (Refs. 5, Appendix E, pp. E- 84 through E-89; 58). Tailings have slumped over the dam face and appear to have at least partially blocked the outlet pipe, causing water to back up into the tailings pile and seep through the dam face. In addition, the upper end of the pipe where the tributary enters is known to become blocked (Refs. 5, Appendix E, p. E-115 and E-116; 58).

Seeps emanating from the face of the tailings dam have extremely high concentrations of several metals, acidity, sulfate, and total dissolved solids. All of the seeps on the dam face exceeded surface water quality criteria applicable to Ore Knob Branch by factors of five or more for aluminum, copper, iron, manganese, silver, zinc, and sulfate when sampled during the ESI (Refs. 5, pp. 40, 41; 58). Sampling has also shown impacts from the tailings pile to other downstream receiving waters. Surface water samples collected from ponds atop the tailings impoundment exceed water quality criteria for several metals and pH. Soil samples collected adjacent to the tailings impoundment also contain elevated concentrations of various metals (Refs. 5, p. 40; 58).

OPERATIONAL HISTORY

Ore Knob Mine was reportedly worked for iron when operations first began (Ref. 30, p. 5); the dates of this activity are not known (Ref. 30, p. 5). The ore contained too much copper and sulfur; therefore, it was not suitable to make wrought iron (Ref. 30, p. 5). Copper mining at Ore Knob reportedly began about 4 years before the Civil War (Ref. 30, p. 5).

The first known shaft at Ore Knob was sunk in 1855, and mining of “black ore” reportedly occurred between 1855 and 1856 (Refs. 36, p. 1; 40, p. 44). In 1859, four shafts were sunk on the lode, with a tunnel driven across the vein at the water level. The shafts were 90, 40, 30, and 40 feet deep, respectively (Refs. 32, p. 19; 40, p. 44). Ore was transported about 60 miles to Wytheville, Virginia, in oxen-drawn wagons (Refs. 30, p. 5; 31, p. 3).

The mine was expanded and operated from 1873 to 1883 (Ref. 30, p. 5). This operation sank seven new shafts and deepened the four existing shafts: two shafts were over 400 feet in depth and the others ranged from 60 to 250 feet (Ref. 40, p. 44). Nine of these shafts are shown on Figure 2-2 of Reference 5. At least one, former shaft 2-S, remains partly open and is protected by a chain-link fence. The engine shaft was filled with stumps in the years since 2001 (Ref. 5, pp. 9, 10).

Initially, the Ore Knob mine used the “Hunt and Douglas” process (Ref. 34, p. 27); it was the second mine in the United States to use this process (Ref. 33, p. 1). The Hunt and Douglas process is a wet process in which copper is removed from ores in a dissolved state using a watery neutral protochlorid

18 Site Description

solution of iron and common salt as a solvent (Ref. 28, p. 5). The Hunt and Douglas process also included the treatment of copper which involved grinding and calcining the ore, dissolving and precipitating the copper, and melting and refining the copper (Ref. 28, p. 7). The Hunt and Douglas process was subsequently discontinued when the ore was no longer usable (Rec. 34, p. 27). Subsequently, a smelting process was used at Ore Knob (Ref. 34, p. 27). The smelting process involved two reducing furnaces and a refining furnace that used charcoal as fuel (Ref. 31, p. 3). This smelter was reportedly located a few hundred feet from the mine (Ref. 34, p. 27). Prior to roasting, the ore was stored in piles on the ground surface (Ref. 34, p. 27). Ore was piled on burning wood heaps and roasted for 5 to 7 weeks, by which time most of the sulfur would have been driven off. The roasted ore was then smelted with charcoal in shaft furnaces and refined to 99 percent pure copper (Ref. 30. p. 5). During the 10-year period from 1873 to 1883, about 25,000,000 pounds of copper were produced from over 200,000 tons of ore (Ref. 31, p. 3).

In 1896, the No. 2 shaft was sunk an additional 25 to 30 feet (Ref. 31, p. 3). In either 1896 or 1897, several carloads of hand-sorted slag were shipped from the most northerly slag dump (Ref. 31, p. 3). In 1913, a carload containing 72,739 pounds of slag and copper bottoms was shipped to New Jersey. The shipment contained 12.9 ounces of gold, 112 ounces of silver, and 14,672 pounds of copper. In 1917 or 1918, the mine was dewatered and a tunnel was driven under the No. 4 shaft. Several cars of ore were mined and shipped. In 1927, the tunnel under the No. 4 shaft was reopened and some drifts were driven to the southwest. There is no information on ore that was mined at that time (Ref. 31, pp. 3, 4).

In 1942, the Bureau of Mines conducted an exploration program that involved drilling 20 holes totaling 4,945 feet along the strike of the vein, 75 feet of drifts and cross cuts, excavating for an underground drilling station, and rehabilitating part of the mine drifts for sampling (Refs. 31, pp. 2, 5; 40, pp. 44, 45). Samples were collected from the drill holes to identify locations of copper ore (Ref. 31, p. 5). During these exploratory activities, adits were cleared (Ref. 31, p. 5). Based on the Bureau of Mines diagrams, the shafts are located from west to east in the areas currently referred to as the Former 1950s Mine and Mill site and the 19th Century Operations Area (Refs. 5, Figure 2-2; 31, Figure 2).

Nipissing Mines Co., Ltd. began a new exploration program at Ore Knob in 1953 (Refs. 27, p. 12; 40, p. 45). This included an electromagnetic survey and 38 drill holes totaling 27,752 feet. Ore was intercepted in 15 holes, with the deepest ore located at 1,150 feet below land surface (bls). The program delineated reserves of 1,330,300 tons of 3.0 percent copper and 14 percent sulfur (Ref. 40, p. 45). This exploration program led to the reopening of the mine in 1957 (Ref. 33, p. 3).

In 1956, the main shaft (the “working shaft” on Figure 2-2 of Reference 5) was sunk to a depth of 1,037 feet (Ref. 40, p. 45). The collar was reinforced with concrete down to 55 feet, and six levels were opened for work starting at 280 feet (Ref. 40, p. 45). The mine was dewatered from the 980-foot level with one or more 300-gallon-per-minute (gpm) pumps (Ref. 40, p. 46). The head frame was 105 feet high, and skips dumped ore and waste directly into a partitioned steel bin with a capacity of 700 tons of ore and 150 tons of waste (Refs. 27, p. 12; 40, p. 47). This ore bin is believed to be the former coarse ore/waste bin depicted on Figure 2-3 of Reference 5. Ore was initially crushed in a jaw-type primary crusher and then a secondary cone crusher and then ground in a ball mill. There were two 350-tons-per-day (tpd) concentration circuits, with ground ore distributed equally to the two circuits. After thickening and filtering, the concentrates were fed to two ore bins (Ref. 40, p. 47). Both ore bins are still present (one standing and one collapsed) at the Former 1950s Mine and Mill site (Ref. 5, Figure 2-3, Appendix E, p. E-55). Concentration was conducted using a flotation process, followed by thickening and filtering of concentrate, which eventually achieved a total copper recovery of about 94 percent (Ref. 40, p. 47). The combined 700 tpd circuits were able to handle 940 tpd (Ref. 33, p. 5). Initial plans were for an iron circuit to recover iron sulfide concentrate. This circuit took tailings from the copper circuit and floated the iron sulfide. This unit acted as a copper scavenger if the iron circuit was not included (Ref. 40, p. 47). It is not known if the iron circuit was ever installed. The foundation of the building where flotation took place still remains at the Former 1950s Mine and Mill site (Ref. 5, Figure 2-3, Appendix E, pp. E-56, E- 57). Concentrate was thickened and filtered before being loaded into 300-ton and 400-ton bins in a concrete building (still standing), from which it was gravity-dumped into trucks underneath the bins.

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Concentrate was trucked 13 miles to Smethport, near West Jefferson, and shipped by rail to custom smelters (Ref. 40, p. 47). An electrical substation was constructed at the Former 1950s Mine and Mill site to supply electricity (Ref. 33, p. 3). The concrete building and substation still remain at the Former 1950s Mine and Mill site (Ref. 5, Figure 2-3, Appendix E, pp. E-53, E-54).

Water for operational activities was pumped from a company-built dam through 6,200 feet of 8-inch pipe. About 600 gpm were pumped into two wood-stave storage tanks (Refs. 27, p. 12; 40, p. 47). The approximate location of the water tanks is depicted on a plan of the 1950s Mine and Mill (Ref. 52, p. 4). The mine operators reportedly purchased an acre of land, installed a dam on Peak Creek, and put in a 0.75-mile pipe that pumped the water to two storage tanks and the plant (Refs. 27, p. 12; 33, p. 5; 40, p. 47.

Tailings from mining operations were conveyed via pipeline to the tailings impoundment (main tailings pile, Source No. 1) located about 0.6 mile northwest of the Former 1950s Mine and Mill site (Refs. 3; 5, Figure 2-1; 42, pp. 6, 8; 52, p. 4). Based on observations made during the preliminary evaluation of the dam, it appears that the dam was constructed of tailings and natural stream bottom soils (Refs. 48, p. 2). To provide for drainage of the impoundment, a decant structure consisting of a 24-inch reinforced concrete pipe, drop-inlet and stand-pipe (sluice) was constructed (Ref. 42, p. 8). This concrete pipe was laid under the tailings (Ref. 48, p. 2). In recent years, tailings from the eroding dam face have sloughed downward and now cover the outlet end of the pipe. This has apparently led to an increase in the water level within the tailings impoundment (main tailings pile) and resulted in seepage emerging from more locations higher on the dam face.

Through the end of 1961, the Ore Knob deposit had produced over 35,000 tons of copper, 9,400 ounces of gold, and 145,000 ounces of silver (Ref. 35, p. 2). Mining operations at Ore Knob ceased in 1962 when the ore body was mined out (Ref. 33. p. 7).

WASTE GENERATION AND MANAGEMENT

The 19th century operation most likely generated various types of slag and roasting wastes as well as waste rock and poor ore (Ref. 24, p. 27). These waste materials most likely were disposed of in areas near the mine shafts. Poor ore that remained on the property might have been processed at a later date in an attempt to recover the remaining copper (Ref. 34, p. 27). During the 10-year period from 1873 to 1883, about 25,000,000 pounds or 12,500 tons were produced from 200,000 tons of ore; therefore, the majority of the ore that was mined resulted in waste material (Ref. 31, p. 3). A partially barren area shown on Figure 2-2 of Reference 5 contains waste materials up to several feet deep, with at least some of the material appearing to have been smelted or roasted (Ref. 5, p. 12, Figure 2-2, Appendix E, p. E-30, E- 31, E-32, E-36). The upper end of the main tailings pile (Source No. 1) contains at least several dozen cubic yards of material that appears to be slightly coarser than the modern tailings material. This material could be waste fines from the roasting operation (Ref. 5, p. 12, Appendix E, p. E-80 through E-84).

The 1957 to 1962 operations on the former mill site would have generated a large quantity of tailings (over 97 percent of the mined ore would have remained as tailings) and minor amounts of waste rock (minor compared to the tailings, but likely in the thousands of tons). About 20,000 cubic yards (±20 percent) of tailings were disposed in what is now a dry pile just north of the mill site (Ref. 5, Figures 2-2 and 2-3). Most of the tailings generated during the operation of the Former 1950s Mine and Mill (about 720,000 cubic yards), were disposed of in the 20-acre main tailings pile (Source No. 1) located northeast of the mill (Refs. 5, p. 3; 42, p. 6). AMD continues to discharge from the mine adits; although anoxic limestone drains (ALDs) were constructed at the mouth of the adits (Ref. 42, pp. 12, 13). While these ALDs have improved the pH of the discharge to about 5 standard units, low acidity waste measured at 60 milligrams per liter as calcium carbonate continues to discharge from the adits, impacting downstream surface water bodies including Ore Knob Branch, Little Peak Creek, and Peak Creek (Refs. 5, pp. 63 through 65, Figure 5-16; 29, p. 1; 45, 2; 42, pp. 13, 14).

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PREVIOUS INVESTIGATIONS

A limited number of investigations have been conducted at Ore Knob. From 1992 to 1994, the North Carolina Division of Water Quality, Section 319 Grant Program, conducted reclamation activities at Ore Knob (Refs. 39, pp. 1, 5). The grant was funded by EPA (Ref. 29, p. 1). The purpose of the study was to address acid drainage from Ore Knob, by intercepting and treating ground water seeps that discharge from the mine (Ref. 29, p. 1; 39, p. 5). The reclamation activities were conducted in two phases (Ref. 39, p. 5). Phase I involved constructing a treatment system, revegetating the tailings pile and tailings pile dam, and establishing an artificial wetland as a retention area (Refs. 29, p. 1; 39, p. 5). During Phase I, the ground water seeps exhibited low dissolved oxygen as they exited the tailings pile and were routed to the ALDs to raise the pH, and then discharged to the retention area for oxidized and precipitated metals (Refs. 39, p. 5; 42, p. 18). In addition, the tailings area was repaired and the face of the dam was reshaped because it was subject to erosion. Municipal sludge and lime were used to revegetate the tailings area. However, revegetation of the dam was unsuccessful (Ref. 39, p. 5). At the end of Phase I, the pH of the entire mine did not improve, but the pH of the drainage seeps that were routed through the ALDs improved from 3 to 5. Phase I of the reclamation project was completed in 1992 (Ref. 39, p. 5).

Phase II of the 319 grant program involved installing additional ALDs at seeps that were not previously identified, attempting to vegetate the face of the dam, installing erosion control devices in the tailings area, and planting more wetland seeds upstream of the tailings area (Ref. 39, p. 5). In addition, the North Carolina Department of Transportation assisted with establishing test plots on the tailings area to determine germination and survivability of different seed mixtures and vegetation (Refs. 39, pp. 5, 6; 41, pp. 1 through 3). At the end of the Phase II reclamation activities, the tailings area had an established vegetative layer, erosion had been significantly reduced, wetlands had been established above and below the tailings area, and the pH of the newly identified seeps had increased from 3 to 5. Attempts to revegetate the face of the dam were still not successful (Ref. 39, p. 6).

To evaluate the effectiveness of the remediation (reclamation) activities, toxicity tests, benthic macroinvertebrate studies, fish community surveys, and chemical analyses were performed by the North Carolina Division of Water Quality before the remediation (reclamation) activities began in 1991 (Ref. 39, p. 6). The results of the studies conducted before reclamation activities commenced are summarized below. North Carolina water quality standards for pH, copper, zinc, and iron were violated at Ore Knob Branch above its confluence with Peak Creek (Ref. 39, p. 6, Appendix B, pp. B4, B6). Taxa (organism groups) in Peak Creek were rich above its confluence with Ore Knob Branch, but were poor above its confluence with the South Fork New River (Ref. 39, p. 6, Appendix B, pp. B3 through B6). Peak Creek above Ore Knob Branch supported a fish community; however, the waters in Peak Creek below Ore Knob Branch were deemed unsuitable to support fisheries (Ref. 39, p. 6, Appendix B, pp. B3 through B6).

Follow-up studies conducted in 1994 after the completion of reclamation activities revealed improvements in the wetland (rushes and soft stem bulrush) growth above and below the tailings dam (Ref. 39, p. 6, Appendix B, p. B17). The results showed that pH levels ranged from 2.9 to 3.5 and chemical analyses revealed that iron, copper, and zinc were still above the North Carolina water quality standards in Ore Knob Branch above Peak Creek (Ref. 39, pp. 6, 7, Appendix B, pp. 6, 7, Appendix B, pp. B17 through B19).

Follow-up studies conducted in 1996 indicated that Ore Knob Branch above Peak Creek, Peak Creek below Ore Knob Branch, and Little Peak Creek were devoid of fish (Ref. 39, p. 7, Appendix B, pp. B20, B22, B24). Ore Knob Branch continued to be acidic and had high dissolved metals and a pH of 3.2 (Ref. 39, Appendix B, p. B21). The pH of Peak Creek below Ore Knob Branch ranged from 4.0 to 4.6, but recovered to about 5.5 near its confluence with the South Fork New River (Ref. 39, Appendix B, p. B20). The follow-up studies indicated that there had been no improvement associated with the mine reclamation activities, and concluded that efforts to lessen the impact from Ore Knob resulted in no demonstrable improvements in water quality in Peak Creek and Little Peak Creek. Also, drainage from Ore Knob continued to eliminate most of the stream fauna along 3 miles of Peak Creek and 2 miles of Little Peak Creek (Ref. 39, Appendix B, p. B21).

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In the late 1990s, the Huntington District of the U.S. Army Corps of Engineers (USACE) and the North Carolina Department of Environment and Natural Resources (NCDENR) prepared a Detailed Project Report and Environmental Assessment for Ore Knob under Section 206 of the Water Resources Development Act of 1996 (PL 104-303) (Ref. 42, p.1) The purpose of the report was to examine alternative strategies for reducing the amount and severity of AMD to receiving waters and to improve their aquatic habitats. The report outlined alternative approaches to improving conditions at the tailings area and assessed their environmental impacts. The alternatives identified in the report included reclamation of the tailings area to involve re-grading and establishment of vegetation on the tailings pile, repairing the existing drainage system, constructing an open limestone channel and aerobic wetlands to treat AMD, establishing erosion control, and repairing the wetland embankment to provide additional retention time before discharges (Ref. 42, pp. 2, 3). Due to funding issues, this project was put on hold indefinitely (Ref. 46, p. 7).

In July 2007, EPA and Black & Veatch, on behalf of EPA, conducted an integrated site assessment at Ore Knob. The goals of the investigation were to determine the condition of the pipe that conveys water from above the main tailings pile (tailings impoundment), underneath the tailings, to the outlet at the dam, and to document what hazardous substances have been, or potentially can be, released from the mine sources (Ref. 5, p. 14). The results of the sampling event were documented in an ESI report dated September 2008 (Ref. 5). Analytical results for samples collected from various locations throughout the 19th Century Operations Area, the Former 1950s Mine and Mill area, the main tailings pile, and surface water bodies that receive runoff from the Ore Knob property, indicate that the following hazardous substances are present in sources on the property and in downstream receiving waters: arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel, selenium, silver, and zinc (Ref. 6).

In October 2008, the EPA Region 4 Emergency Response and Removal Branch began a time-critical removal action at Ore Knob (Ref. 59, p. 2). Activities planned for the removal action include widening and grading the access road to provide accessibility for heavy equipment, excavation of the sediment settling pond, and collecting samples from the tailings dam in order to determine the stability of the dam (Ref. 59, pp. 1, 2). As of December 5, 2008, about 5,900 cubic yards of sediment were excavated from the settling pond and placed on the tailings dam (Ref. 59, pp. 4, 6, 8, 10). In order to prevent sludge from entering the tailings dam inlet pipe, a barrier of sawdust and topsoil was constructed around the sludge pile. Also sawdust was added to the excavated sludge to stabilize the material (Ref. 59, p. 11). Planned removal activities include a final design of a diversion channel and slope re-facing, and excavation of the diversion channel once the final design is approved (Ref. 59, p. 11).

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2.2 SOURCE CHARACTERIZATION

2.2.1 SOURCE IDENTIFICATION

Number of source: 1

Name of source: Main Tailings Pile

Source Type: Pile

Description and Location of Source (with reference to a map of the site):

Source No. 1 is the 20-acre main tailings pile located in the northern portion of the 19th Century Operations Area, and primarily contains tailings from the 1957 to 1962 operational period, although the upper end may contain residual fines from 19th century roasting and smelting (Refs. 5, p. 3, Figure 2-2; 42, p. 6; 45, pp. 1, 6; 52, p. 4; 61). Source No. 1 was constructed in the 1950s for disposal of waste material after minerals were extracted from the ore by grinding and milling or by other means (Refs. 42, p. 8; 45, pp. 1, 6). Photographs of the tailings pile are shown in References 5, Appendix E, p. E-112; 47, pp. 4 to 7; 58.

Source No. 1 is also known as the tailings impoundment (Refs. 5, p. 3; 45, p. 1). A slurry of mill tailings and ground water from the 1950s Former Mine and Mill was pumped to the main tailings impoundment (Ref. 45, p. 2). The water from the impoundment flowed to an outlet (discharge) pipe located in a dam constructed at the northern end of the impoundment. The pipe discharged to Ore Knob Branch. The tailings water has since evaporated, leaving the main tailings pile with the dam on the northern end. The main tailings pile dam consists of what appears to be a waste rock “starter dam” that serves as a buttress for the upper dam. The upper dam appears to have been constructed of successive lifts of tailings using the upstream method of construction (Refs. 5, pp. 3, 4, 12; 25; 45, pp. 1, 3; 47, p. 1, Logbook 1, p. 4; 58). The dam is about 70 feet high and 700 feet wide. Photographs of the main tailings pile dam is shown on Reference 5, Appendix E, p. E-112 and Reference 58.

To provide for drainage of the pile, a decant structure consisting of a 24-inch reinforced concrete pipe, drop-inlet and stand-pipe (sluice) was constructed (Ref. 42, p. 8). The stand-pipe was about 24 by 24 inches and sloped with the natural topography. By placing boards on the stand-pipe the water level of the impoundment could be regulated, however the boards subsequently were removed and the area currently impounds water only in a few low depressions at the head of the drainage and along the perimeter of the tailings pile (Ref. 42, p. 8). The drop-inlet and stand-pipe are located about 1,600 feet from the face of the tailings (Refs. 5, Figure 2-4; 42, p. 8; 48, p. 7). Photographs of the tailings pile are shown in Reference 5, Appendix E, pp. E-105, E-107, E-109, E-110 through E-113. The sediment pond located at the base of the tailings dam is shown in Reference 5, Appendix E, p. E-114. A tributary entering the southwest corner of the tailings pond is shown in Reference 5, Appendix E, p. E-115. The tributary appears to be affected by AMD. The inlet pipe that the tributary enters is shown in Reference 5, Appendix E, page E-116.

During the 2007 ESI sampling event, waste samples were collected from several locations on the tailings pile (Ref. 5, Figure 3-4, Table 3-5). Table 1 provides the descriptions of the locations of the waste samples collected from Source No. 1 and the list of detected contaminants associated with each sampling location (Refs. 5, Table 3-5, Appendix E, pp. E-93 through E-113; 7, Book 4). The soil sampling locations are shown in Figure 2 of this HRS documentation record.

23 Source Characterization

Source No. 1

TABLE 1: Summary of Waste Samples from Source No. 1 – Main Tailings Pile

Sample Hazardous Station Sample Sample Depth Substances ID Description of Location Description Date (bgs) Detected References 5, Figures 2-4 and 3-4, Table 3-5 and Southwest lobe of main tailings pile, center 0 – 12 Appendix E, pp. E-93, E-94; 7, Book 4, p. OK351 of clearing, about 50 feet west of gully at Tailings 7/17/2007 Copper inches 8; see Table 2 of this HRS documentation inlet to pile record 5, Figures 2-4 and 3-4, Table 3-5 and Southwest lobe of main tailings pile, about 2.5 – 2.8 Cadmium, Appendix E, pp. E-95, E-96; 7, Book 4, p. OK352 2.5 feet below top of gully, and 0.5 feet Tailings 7/17/2007 feet copper, zinc 9; see Table 2 of this HRS documentation above water record 5, Figures 2-4 and 3-4, Table 3-5 and Near the southern end of the main tailings 0 – 18 Appendix E, pp. E-97, E-98; 7, Book 4, p. OK353 pile, about 80 feet north of pond in Tailings 7/17/2007 Copper, mercury inches 7; see Table 2 of this HRS documentation southwestern portion of main tailings pile record Center of main tailings pile, about 2/3 of 5, Figures 2-4 and 3-4, Table 3-5 and the way from the southwest distal end 0 -12 Appendix E, pp. E-99, E-100; 7, Book 4, p. OK354 (where tributary enters) to the crest of the Tailings 7/17/2007 Mercury inches 6; see Table 2 of this HRS documentation dam, and about 500 feet south of the dam record crest About 230 feet south of the crest of the Cadmium, 5, Figures 2-4 and 3-4, Table 3-5 and tailings dam, and about 1/3 of the way from 0 – 18 chromium, Appendix E, pp. E-101, E-102; 7, Book 4, OK355 Tailings 7/17/2007 the dam crest to the southwest distal end of inches copper, mercury, p. 4; see Table 2 of this HRS documentation the main tailings pile zinc record 5, Figures 2-4 and 3-4, Table 3-5 and Near the centerline of the tailings dam, 0 – 12 Appendix E, pp. E-103, E-104;; 7, Book 4, OK356 Tailings 7/17/2007 Copper, mercury about 2 feet below the dam crest inches p. 3; see Table 2 of this HRS documentation record 5, Figures 2-4 and 3-4, Table 3-5 and Near the centerline of the tailings dam Appendix E, pp. E-105, E-106; 7, Book 4, about halfway up the dam face, and about 3 0 – 12 OK357 Tailings 7/17/2007 Copper, mercury p. 2; see Table 2 of this HRS documentation feet below the transition from yellowish tan inches record to reddish brown tailings

24 Source Characterization

Source No. 1

TABLE 1: Summary of Waste Samples from Source No. 1 – Main Tailings Pile

Sample Hazardous Station Sample Sample Depth Substances ID Description of Location Description Date (bgs) Detected References 5, Figures 2-4 and 3-4, Table 3-5 and Near the centerline of the tailings dam 0 – 12 Appendix E, pp. E-107, E-108; 7, Book 4, OK358 about 5 feet above tailings starter dam Tailings 7/17/2007 Copper, mercury inches p. 1; see Table 2 of this HRS documentation contact , near the base of the upper slope record Notes: bgs Below ground surface ID Identification No. Number OK Ore Knob Mine Site

25 Source Characterization

Source No. 1

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

The waste samples listed in Table 2 were collected from the Main Tailings Pile (Source No. 1) by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). The concentrations of metals detected in the waste samples were compared to concentrations of metals in native soil samples to demonstrate the relative increase of metal concentrations and availability in Source No. 1 over naturally occurring levels in native soils. Table 2 summarizes only the metals and concentrations detected significantly above naturally occurring levels, with the consideration of data qualifiers. Table 3 summarizes the concentrations of metals detected in native (background) soil samples. Only the greatest concentration of each analyte from the soil samples is listed in Table 3. Background soil samples were collected in areas with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area. Background soil samples consist primarily of moderate brown to moderate yellowish brown silty sand with fragments of schist and quartzite. Samples were collected either from 0 to 6 inches or 0 to 12 inches in depth. All soil samples were collected using hand augers (Ref. 5, p. 27). The locations of the soil samples are depicted on Figure 3 of this HRS documentation record.

All waste samples listed in Table 2 are grab samples that were collected from various locations throughout the Main Tailings Pile (Refs. 5, p. 16, Figure 3-4, Table 3-5; 7, Book 4). The waste and background soil samples were collected in accordance with the EPA Region 4, Science and Ecosystem Support Division (SESD) operating procedures SESDPROC-302-R0, and the final sampling plan (Refs. 5, pp. 14, 20, 21; 16, p. 13; 51). The chain of custody records and traffic reports are contained in Reference 19 and sample delivery groups are contained in Reference 8. The samples were analyzed under the EPA Contract Laboratory Program (CLP), for total metals and cyanide analysis using the CLP Statement of Work (SOW) ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Refs. 5, p. 22; 6, pp. 2 through 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contain internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific CLP Contract Required Quantitation Limits (CRQLs) that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). Field sample data sheets are contained in Reference 7, Book 4. The locations of the waste samples listed in Table 2 are provided in Reference 5, Figure 3-4 and in Figure 2 of this HRS documentation record. .

26 Source Characterization

Source No. 1

TABLE 2: Analytical Results for Source No. 1

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References Waste Samples 2,600J (2,600) 6, p. 46; 7, Book 4, p. 8; 19, p. 6; OK351-WA-001 Copper 2.8 mg/kg mg/kg 22, p. 22 OK352-WA-001 Cadmium 3.1 mg/kg 0.70 mg/kg 6, p. 47; 7, Book 4, p. 9; 19, p. 6 540J (540) 6, p. 47; 7, Book 4, p. 9; 19, p. 6; OK352-WA-001 Copper 3.5 mg/kg mg/kg 22, p. 22 1,400J (1,400) 6, p. 47; 7, Book 4, p. 9; 19, p. 6; OK352-WA-001 Zinc 8.4 mg/kg mg/kg 22, p. 22 680J (680) 6, p. 24; 7, Book 4, p. 7; 19, p. 4; OK353-WA-001 Copper 2.9 mg/kg mg/kg 22, p. 23 OK353-WA-001 Mercury 0.22 mg/kg 0.10 mg/kg 6, p. 24; 7, Book 4, p. 7; 19, p. 4 OK354-WA-001 Mercury 0.64 mg/kg 0.10 mg/kg 6, p. 26; 7, Book 4, p. 6; 19, p. 4 6, p. 27; 7, Book 4, p. 4; 19, p. 4; OK355-WA-001 Cadmium 20J (20) mg/kg 0.55 mg/kg 22, p. 23 4,800J (4,800) 6, p. 27; 7, Book 4, p. 4; 19, p. 4; ; OK355-WA-001 Copper 2.8 mg/kg mg/kg 22, p. 23 OK355-WA-001 Mercury 0.20 mg/kg 0.11 mg/kg 6, p. 27; 7, Book 4, p. 4; 19, p. 4 1,400J (933.33) 6, p. 27; 7, Book 4, p. 4; 19, p. 4; OK355-WA-001 Zinc 6.6 mg/kg mg/kg 22, p. 23 6, p. 28; 7, Book 4, p. 5; 19, p. 4; OK355-WA-001D Cadmium 5.9J (5.9) mg/kg 0.57 mg/kg 22, p. 24 100J (77.52) 6, p. 28; 7, Book 4, p. 5; 19, p. 4; OK355-WA-001D Chromium 1.1 mg/kg mg/kg 22, p. 24 7,300J (7,300) 6, p. 28; 7, Book 4, p. 5; 19, p. 4; OK355-WA-001D Copper 5.7 mg/kg mg/kg 22, p. 24 OK355-WA-001D Mercury 0.26 mg/kg 0.11 mg/kg 6, p. 28; 7, Book 4, p. 5; 19, p. 4 1,600J 6, p. 28; 7, Book 4, p. 5; 19, p. 4; OK355-WA-001D Zinc 6.8 mg/kg (1,066.67) mg/kg 22, p. 24 1,400J (1,400) 6, p. 20; 7, Book 4, p. 3; 19, p. 3; OK356-WA-001 Copper 2.9 mg/kg mg/kg 22, p. 25 OK356-WA-001 Mercury 0.71 mg/kg 0.11 mg/kg 6, p. 20; 7, Book 4, p. 3; 19, p. 3 2,200J (2,200) 6, p. 22; 7, Book 4, p. 2; 19, p. 4; OK357-WA-001 Copper 2.9 mg/kg mg/kg 22, p. 25 OK357-WA-001 Mercury 0.68 mg/kg 0.12 mg/kg 6, p. 22; 7, Book 4, p. 2; 19, p. 4

27 Source Characterization

Source No. 1

TABLE 2: Analytical Results for Source No. 1

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 1,400J (1,400) 6, p. 18; 7, Book 4, p. 1; 19, p. 3; OK358-WA-001 Copper 2.8 mg/kg mg/kg 22, p. 25 OK358-WA-001 Mercury 0.50 mg/kg 0.11 mg/kg 6, p. 18; 7, Book 4, p. 1; 19, p. 3

Notes:

28 Source Characterization

Source No. 1

TABLE 3: Background Soil Sample Analytical Results for Comparison to Source No. 1 Waste Sample Results Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 17J (21.93) 6, p. 126; 7, Book 5, p. 9; 19, p. 12; 22, OK500-SL-001 Chromium 1.2 mg/kg mg/kg p. 2 OK501-SL-001 Cadmium 0.64UJ mg/kg 0.64 mg/kg 6, p. 98; 7, Book 5, pp. 1, 2; 19, p. 10 79J (96.38) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Copper 3.1 mg/kg mg/kg 12; 22, p. 4 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Mercury 0.11U mg/kg 0.11 mg/kg 12 120J (180) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Zinc 7.5 mg/kg mg/kg 12; 22, p. 5

Notes:

( ) Concentration was adjusted in accordance with References 8, 10, 12, and 22 as a conservative measure to illustrate the relative increase of hazardous substances over those in native soil levels ID Identification number J Estimated concentration. While quantitation may be estimated, the presence of the substance is not in doubt. mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob Mine Site SL Soil sample U The analyte was not detected at or above the reporting limit. UJ Analyte was not detected at or above the reporting limit. The value (quantitation) is an estimate, but the presence of the analyte is not in doubt.

29 Source Characterization

Source No. 1

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Waste samples collected from Source No. 1 contain cadmium, chromium, copper, mercury, and zinc (Ref. 6, pp. 18, 20, 22, 24, 26, 27, 28, 46, and 47) (also see Table 2 of this HRS documentation record). Source No. 1 is a 20-acre tailings pile that primarily contains tailings from the 1957 to 1962 operational period, although the upper end may contain residual fines from the 19th Century Operational period (Ref. 5, p. 3). Seeps are located in the dam on the north end of Source No. 1. These seeps discharge into Ore Knob Branch located downstream of Source No. 1 (Refs. 3; 5, Figures 2-4 and 3-4; 47, pp. 1, 4 through 6). Analytical results for sediment samples collected from Ore Knob Branch and Peak Creek, which receive runoff from Source No. 1, indicate that Source No. 1 has released hazardous substances to the surface water migration pathway as documented in Section 4.0 of this HRS documentation record. During the July 2007 ESI conducted by Black & Veatch, seeps were observed emanating from Source No. 1 and discharging into Ore Knob Branch (Ref. 5, Figures 2-4 and 3-4). Also, the same hazardous substances that were detected in Source No. 1 were also detected in Ore Knob Branch at the location where discharge from Source No. 1 enters Ore Knob Branch (Refs. 5, Figure 3-4; 6, pp. 18 through 47, 107). Surface water runoff from all areas in the 19th Century Operations Area, including Source No. 1, flow to Ore Knob Branch (Refs. 5, Appendix E, p. E-1; 39, p. 5). Therefore, a containment factor value of 10 as noted in Table 4 was assigned for the surface water migration pathway (Ref. 1, Section 4.1.2.1.2.1.1).

TABLE 4: Containment Factors for Source No. 1 Containment Containment Description Factor Value References Gas release to air NS NA Particulate release to air NS NA Release to ground water NS NA Release via overland migration and/or flood: Neither of the following is present: (1) maintained 1, Section 4.1.2.1.2.1.1; 5, Figure engineered cover, or (2) functioning and maintained 10 3-4; 5, Appendix E, p. E-1; 39, p. 5. run-on control system and runoff management See paragraph above. system.

Notes:

NA Not applicable NS Not scored

30 Source Characterization

Source No. 1

2.4.2.1 SOURCE HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, hazardous constituent quantity, as required by Reference 1, Section 2.4.2.1.1.

Hazardous Constituent Quantity Assigned Value: Not scored (NS)

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B, hazardous wastestream quantity, as required by Reference 1, Section 2.4.2.1.2.

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The information available is not sufficient to evaluate Tier C, hazardous volume quantity, as required by Reference 1, Section 2.4.2.1.3.

Volume Assigned Value: 0

2.4.2.1.4 Area

Source No. 1 covers about 871,315 square feet (ft2) in area (Refs. 3; 5, Figure 2-4; 25; 61). The area was determined based on the aerial photography of the source using a geographical information system (GIS) program (Refs. 25; 61).

Sum (ft2): 871,315 ft2 (Ref. 25; 61) Equation for Assigning Value (Ref. 1, Table 2-5): Area (A)/13 Therefore, 871,315 ft2 ÷ 13 = 67,024.23.

Area Assigned Value: 67,024.23

2.4.2.1.5 Calculation of Source Hazardous Waste Quantity Value

A source hazardous waste quantity (HWQ) value of 67,024.23 is assigned for Source No. 1 (Ref. 1, Section 2.4.2.1.5).

Highest value assigned from Reference 1, Table 2-5: 67,024.23

31 Source Characterization

Source No. 2

2.2.1 SOURCE IDENTIFICATION

Number of source: 2

Name of source: Multiple Areas of Contaminated Soil in the 19th Century Operations Area

Source Type: Contaminated Soil

Description and Location of Source (with reference to a map of the site):

Source No. 2 is comprised of multiple areas of contaminated soil in the 19th Century Operations Area of Ore Knob (Ref. 5, Figure 3-2). These areas are defined by Station Nos. OK511, OK512, OK513, OK514, OK519, OK520, OK551, OK553, and OK554 (Ref. 5, Table 3-5, Figure 3-2). Mining activities at the 19th Century Operations Area began prior to 1860 (Refs. 31, p. 2; 34, p. 25; 40, p. 44) and continued until about the mid 1950s when the mill area was opened west of the 19th Century Operations Area (Refs. 5, pp. 3, 9, 10; 40, p. 44). Mining activities included roasting sorted ores and dressed fines, fusion in a shaft furnace for mattes, roasting the mattes in piles, fusion in a shaft furnace for black or pig copper concentrated or double matte, treatment of the salamanders, and fining and refining (Ref. 31, p. 3). During the early years of operation, the mine was one of the largest copper ore mines in the country (Ref. 31, p. 3). After the 1950s mill was opened, shaft mining was employed to remove the ore from the mine (Ref. 42, p. 6). As a result of these extraction practices, mine portals (adits) can be found on the site where the miners entered the ore body horizontally from the surface. Vertical shafts were developed where the miners followed the deposit downward and removed the ore. Rock materials associated with the ore deposit were sometimes brought to the surface and simply dumped near the openings, and can be found surrounding the existing vertical shaft (Ref. 42, p. 6).

During the 2007 ESI, soil samples were collected from areas surrounding the piles of slag, waste rock dumps, roaster waste, and crushed and oxidized wastes located in the 19th Century Operations Area. Table 5 provides the descriptions of the locations of the soil samples collected from Source No. 2, a description of the samples, and the list of contaminants associated with each sampling location (Refs. 5, Figure 3-2; 7, Books 4 and 5). The soil sampling locations are shown in Figure 3. Because the samples were collected from various areas throughout the 19th Century Operations Area, and because the sample locations drain into the same surface water bodies and contained the same hazardous substances, the areas of contaminated soil were combined into one source.

32 Source Characterization

Source No. 2

TABLE 5: Summary of Soil Samples from Source 2 – Contaminated Soil in the 19th Century Operations Area

Sample Hazardous Station Sample Sample Depth Substances ID Description of Location Description Date (inches bgs) Detected References 5, Figures 2-2 and 3-2, Table 3-5 and Waste rock Chromium, In the southern portion of the mining area Appendix E, pp. E-10, E-11, E-12; 7, OK511 and red clay 7/19/2007 0 – 12 copper, mercury, about 200 feet south of former engine shaft. Book 4, p. 20; see Table 8 of this silt nickel Documentation Record 5, Figures 2-2 and 3-2, Table 3-5 and In the southern portion of the mining area Cadmium, Silt with Appendix E, pp. E-13, E-14; 7, Book OK512 about 300 feet southeast of former engine 7/19/2007 0 – 12 copper, mercury, sulfide ore 4, p. 19; see Table 8 of this shaft. silver Documentation Record In the northern portion of the mining area 5, Figures 2-2 and 3-2, Table 3-5 and Silt, sand, Cadmium, about 300 feet north-northeast of former Appendix E, pp. E-15, E-16, E-17; 7, OK513 rock, sulfide 7/19/2007 0 – 12 copper, mercury, engine shaft and about 30 feet below top of Book 4, p. 21; see Table 8 of this ore silver hill, midway down rock dump face. Documentation Record 5, Figures 2-2 and 3-2, Table 3-5 and In the northern portion of the mining area in Silt, rock, Cadmium, Appendix E, pp. E-18, E-19; 7, Book OK514 a waste rock dump about 240 feet north of 7/19/ 2007 0 – 12 oxidized ore copper, mercury 4, p. 23; see Table 8 of this former engine shaft. documentation record 5, Figure 2-2 and 2-3, Table 3-5 and 19th Century Operations Area. Sample Silt with Appendix E, pp. E-24, E-25; 7, Book OK519 collected about 240 feet northeast of the organic 7/19/2007 0 – 12 Mercury 5, p. 4; see Table 8 of this mapped adits (and station OK003). debris documentation record Northwestern portion of the mining area Roasted 5, Figures 2-2 and 3-2, Table 3-5 and about 340 feet northwest of the former material, Appendix E, pp. E-26, E-27; 7, Book OK520 7/19/2007 0 – 6 Mercury, silver engine shaft and about 80 southeast of the sand silt with 4, p. 24; see Table 8 of this road to the tailings impoundment. oxides documentation record On the southwest margin of the former 5, Figures 2-2 and 3-2, Table 3-5 and roaster area, down slope of where erosion Silt soil with Appendix E, pp. E-30, E-31; 7, Book OK551 7/18/2007 0 – 6 Copper would carry material from the former roaster gravel 4, p. 14; see Table 8 of this area. documentation record

33 Source Characterization

Source No. 2

TABLE 5: Summary of Soil Samples from Source 2 – Contaminated Soil in the 19th Century Operations Area

Sample Hazardous Station Sample Sample Depth Substances ID Description of Location Description Date (inches bgs) Detected References Southeast of the former roaster area, near the 5, Figures 2-2 and 3-2, Table 3-5 and center of the suspected foundation of former Silt with Appendix E, pp. E-34, E-35; 7, Book OK553 7/18/2007 0 – 12 Copper, mercury smelter and about 110 feet east of the road to sand 4, p. 16; see Table 8 of this the tailings impoundment. documentation record On the northern margin of the former roaster 5, Figures 2-2 and 3-2, Table 3-5 and area about 10 feet down slope from graded Appendix E, pp. E-36, E-37; 7, Book OK554 Sandy silt 7/18/2007 0 – 6 Copper soil in the base of a small gully and uphill 4, p. 15; see Table 8 of this from grassed, graded land. documentation record

Notes: bgs Below ground surface ID Identification No. Number OK Ore Knob Mine Site

34 Source Characterization

Source No. 2

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

Background Samples

The background soil samples listed in Table 6 were collected for comparison to soil samples collected from multiple areas of contaminated soil located in the 19th Century Operations Area (Source No. 2) (see Figure 3 of this HRS documentation record). The background soil samples were collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). Background soil samples were collected in areas with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area. Background soil samples consist primarily of moderate brown to moderate yellowish-brown silty sand with fragments of schist and quartzite. Samples were collected either from 0 to 6 inches or 0 to 12 inches in depth. All soil samples were collected using hand augers (Ref. 5, p. 27).

The background and source soil samples were collected using the same collection methods in accordance with the SESD operating procedures SESDPROC-300-R0 and the final sampling plan (Refs. 5, pp. 14, 20, 21; 17, p. 16; 51). All soil samples listed in Tables 5 and 6 are grab samples (Ref. 5, p. 15, Figure 3- 2, Table 3-5; 7, Book 5). The chain of custody records and sample delivery groups are contained in References 19 and 8, respectively. The background and source soil samples were analyzed using the same methods under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed both the background and source soil analytical data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific adjusted CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11).

As documented in Tables 5 and 6, the background and source soil samples were collected within the same time frame. The description of the soil samples collected from Source No. 2 in Table 5 indicates that the Source No. 2 soil samples were collected from areas disturbed and impacted by mining activities. The samples contain oxidized ore, waste rock, and stained material. The samples were collected from locations near mining activities such as shafts and roaster areas (see Table 5 of this HRS documentation record). Photographs of the source samples indicate that the locations have been impacted by mining activities, and visible staining is evident (Ref. 5, Appendix E, pp. E-10 through E-35). In contrast, the background soil samples were collected from locations with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area (Ref. 5, p. 27). The background soil sample metal concentrations represent native soil metal concentrations because the background sampling locations were not impacted by mining activities. Both the background and the source soil samples were collected from the Watauga-Fannin-Chandler soil series. This series is described as sloping to very steep, well drained and somewhat excessively drained soils that have a loam subsoil (Ref. 57, General Soil Map, Soil Legend) (also see Figure 3 of this HRS documentation record).

The concentrations of metals detected the background soil samples are summarized in Table 7. The background soil sample analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). These adjusted detection limits are cited in Table 7. Field sample data sheets for the background soil samples are contained in Reference 7, Book 5. Only the greatest concentration of each analyte from the three background samples is listed in Table 7. The chain of custody records and traffic reports are

35 Source Characterization

Source No. 2 contained in Reference 19 and sample delivery groups are contained in Reference 8. The background soil sampling locations are shown on Figure 3 of this HRS documentation record.

36 Source Characterization

Source No. 2

TABLE 6 – Background Soil Sample Locations and Descriptions Sample Depth Sample Sample ID Description of Location Sample Description (inches bgs) Date References 19th Century Operations Area. Sample collected about Very fine silt with 5, p. 27, Figure 3-3, Table 3- 600 feet southwest of the former roaster area, in mature OK500-SL-001 abundant root 0 – 12 7/19/2007 5, Appendix E, pp. E-4, E-5; trees north of residential property and south of Christmas material 7, Book 5, p. 9; 19, p. 12 tree farm. Background sample. 19th Century Operations Area. Sample collected 5, p. 27, Figure 3-2, Table 3- Sandy silt with OK501-SL-001 about170 feet south-southwest of former shaft 2-S, 0 – 6 7/19/2007 5, Appendix E, pp. E-6, E-7; organic debris southwest of the mining area. Background sample. 7, Book 5, pp. 1, 2; 19, p. 10 5, p. 27, Figure 3-2, Table 3- 19th Century Operations Area. Sample collected about Silt with fragments 5, Appendix E, pp. E-8, E-9; OK502-SL-001 220 feet east of former shaft 4-N, northeast of the mining 0 – 12 7/19/2007 of schist and quartz 7, Book 5, pp. 10, 11; 19, p. area. Background sample. 12

Notes: bgs Below ground surface ID Identification number OK Ore Knob Mine Site SL Soil sample

37 Source Characterization

Source No. 2

TABLE 7: Analytical Results for Background Soil Samples for Comparison to Source No. 2 Soil Sample Results Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 17J (21.93) 6, p. 126; 7, Book 5, p. 9; 19, p. 12; 22, OK500-SL-001 Chromium 1.2 mg/kg mg/kg p. 2 OK501-SL-001 Cadmium 0.64UJ mg/kg 0.64 mg/kg 6, p. 98; 7, Book 5, pp. 1, 2; 19, p. 10 7.0J (9.45) 6, p. 98; 7, Book 5, pp. 1, 2; 19, p. 10; OK501-SL-001 Nickel 5.1 mg/kg mg/kg 22, p. 3 79J (96.38) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Copper 3.1 mg/kg mg/kg 12; 22, p. 4 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Mercury 0.11U mg/kg 0.11 mg/kg 12 0.79J (1.37) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Silver 1.3 mg/kg mg/kg 12; 22, p. 5

Notes:

( ) Concentration was adjusted in accordance with References 8, 10, 12, and 22 ID Identification number J Estimated concentration. While quantitation may be estimated, the presence of the substance is not in doubt. mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob Mine Site SL Soil sample U The analyte was not detected at or above the reporting limit. UJ Analyte was not detected at or above the reporting limit. The value (quantitation) is an estimate, but the presence of the analyte is not in doubt.

38 Source Characterization

Source No. 2

Contaminated Samples

The soil samples listed in Table 8 were collected from multiple areas of contaminated soil located in the 19th Century Operations Area (Source No. 2). The soil samples were collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). The chains of custody record and traffic reports are contained in Reference 19 and sample delivery groups are contained in Reference 8. The samples were analyzed under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contain internal EPA Region 4 guidelines) for data review, validation, and verification (Refs. 5, p. 22; 15). The analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample- specific and analyte-specific CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). Field sample data sheets are contained in Reference 7, Books 4 and 5. Because Source No. 2 is comprised of multiple areas of contaminated soil, the concentrations of hazardous substances detected in Source No. 2 were compared to background. The background samples are presented in Tables 6 and 7 of this HRS documentation record. The concentrations of metals detected in Source No. 2 soil samples that are greater than three times the concentrations in the background samples or above the minimum reporting limits if not detected in the background samples are considered to be elevated (Ref. 1, Table 2-3; 11). Table 8 summarizes only the metals and concentrations detected significantly above background, with the consideration of data qualifiers. Estimated concentrations of hazardous substances in Source No. 2 were adjusted in accordance with References 10 and 12. The calculations and bias directions for the estimated concentrations are presented in Reference 22. The soil sampling locations are shown on Figure 3.

TABLE 8: Analytical Results for Source No. 2

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK511-SL-001 Chromium 77 mg/kg 3.6 mg/kg 6, p. 100; 7, Book 4, p. 20; 19, p. 10 490J (490) 6, p. 100; 7, Book 4, p. 20; 19, p. 10; OK511-SL-001 Copper 9.0 mg/kg mg/kg 22, p. 5 OK511-SL-001 Mercury 0.50 mg/kg 0.31 mg/kg 6, p. 100; 7, Book 4, p. 20; 19, p. 10 6, p. 100; 7, Book 4, p. 20; 19, p. 10; OK511-SL-001 Nickel 30J (30) mg/kg 14 mg/kg 22, p. 5 OK512-SL-001 Cadmium 4.2 mg/kg 0.57 mg/kg 6, p. 94; 7, Book 4, p. 19; 19, p. 10 1,400J (1,400) 6, p. 94; 7, Book 4, p. 19; 19, p. 10; OK512-SL-001 Copper 2.8 mg/kg mg/kg 22, p. 6 OK512-SL-001 Mercury 0.44 mg/kg 0.10 mg/kg 6, p. 94; 7, Book 4, p. 19; 19, p. 10 OK512-SL-001 Silver 7.5 mg/kg 1.1 mg/kg 6, p. 94; 7, Book 4, p. 19; 19, p. 10 OK513-SL-001 Cadmium 2.7 mg/kg 0.56 mg/kg 6, p. 95; 7, Book 4, p. 21; 19, p. 10 650J (650) 6, p. 95; 7, Book 4, p. 21; 19, p. 10; OK513-SL-001 Copper 2.8 mg/kg mg/kg 22, p. 6

39 Source Characterization

Source No. 2

TABLE 8: Analytical Results for Source No. 2

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK513-SL-001 Mercury 0.30 mg/kg 0.11 mg/kg 6, p. 95; 7, Book 4, p. 21; 19, p. 10 OK513-SL-001 Silver 4.7 mg/kg 1.1 mg/kg 6, p. 95; 7, Book 4, p. 21; 19, p. 10 OK513-SL-001D Cadmium 7.0 mg/kg 0.58 mg/kg 6, p. 96; 7, Book 4, p. 22; 19, p. 10 2,600J (2,600) 6, p. 96; 7, Book 4, p. 22; 19, p. 10; OK513-SL-001D Copper 2.9 mg/kg mg/kg 22, p. 6 OK513-SL-001D Mercury 0.60 mg/kg 0.11 mg/kg 6, p. 96; 7, Book 4, p. 22; 19, p. 10 OK513-SL-001D Silver 9.4 mg/kg 1.2 mg/kg 6, p. 96; 7, Book 4, p. 22; 19, p. 10 OK514-SL-001 Cadmium 3.3 mg/kg 0.61 mg/kg 6, p. 97; 7, Book 4, p. 23; 19, p. 10 2,600J (2,600) 6, p. 97; 7, Book 4, p. 23; 19, p. 10; OK514-SL-001 Copper 3.0 mg/kg mg/kg 22, p. 6 OK514-SL-001 Mercury 0.21 mg/kg 0.12 mg/kg 6, p. 97; 7, Book 4, p. 23; 19, p. 10 OK519-SL-001 Mercury 0.15 mg/kg 0.12 mg/kg 6, p. 124; 7, Book 5, p. 4; 19, p. 10 OK520-SL-001 Mercury 0.18 mg/kg 0.12 mg/kg 6, p. 93; 7, Book 4, p. 24; 19, p. 10 9.6J (5.52) 6, p. 93; 7, Book 4, p. 24; 19, p. 10; OK520-SL-001 Silver 1.3 mg/kg mg/kg 22, p. 7 300J (300) 6, p. 71; 7, Book 4, p. 14; 19, p. 7; OK551-SL-001 Copper 2.8 mg/kg mg/kg 22, p. 7 680J (680) 6, p. 74; 7, Book 4, p. 16; 19, p. 7; OK553-SL-001 Copper 3.1 mg/kg mg/kg 22, p. 7 OK553-SL-001 Mercury 0.76 mg/kg 0.12 mg/kg 6, p. 74; 7, Book 4, p. 16; 19, p. 7 290J (290) 6, p. 75; 7, Book 4, p. 15; 19, p. 8; OK554-SL-001 Copper 2.6 mg/kg mg/kg 22, p. 8

Notes:

40 Source Characterization

Source No. 2

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Soil samples collected from Source No. 2 contain cadmium, chromium, copper, mercury, nickel, and silver (Ref. 6, pp. 71, 74, 75, 93 through 97, 100, 124) (also see Table 8 of this HRS documentation record). Source No. 2 consists of contaminated soil in the mining area primarily around the former engine shaft (Ref. 5, Figures 2-2, 3-2). Analytical results of sediment samples collected from drainage routes that receive runoff from Source No. 2 indicate that hazardous substances have migrated from Source No. 2 (Refs. 5, Figure 3-2; 6, pp. 105 and 132). During the 2007 sampling event, soil samples collected from drainage areas in the 19th Century Operations Area contained the same hazardous substances as detected in Source No. 2 (Refs. 6, pp, 122, 128, 127; 7, Book 5, pp. 5, 6, 8). Surface water runoff from all areas in the 19th Century Operations Area, including Source No. 2, flow to Ore Knob Branch (Refs. 5, Appendix E, p. E-1; 39, p. 5). A containment factor value of 10 as noted in Table 9 was assigned for the surface water migration pathway (Ref. 1, Section 4.1.2.1.2.1.1).

TABLE 9: Containment Factors for Source No. 2 Containment Containment Description Factor Value References Gas release to air NS NA Particulate release to air NS NA Release to ground water NS NA Release via overland migration and/or flood: 1, Section 4.1.2.1.2.1.1; 5, Figure Neither of the following is present: (1) maintained 2-2, 3-2, Table 3-5; 7, Book 4, p. engineered cover, or (2) functioning and maintained 10 14; 5, Appendix E, p. E-1. See run-on control system and runoff management paragraph above. system.

Notes:

NA Not applicable NS Not scored

41 Source Characterization

Source No. 2

2.4.2.1 SOURCE HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, hazardous constituent quantity, as required by Reference 1, Section 2.4.2.1.1.

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B, hazardous wastestream quantity, as required by Reference 1, Section 2.4.2.1.2.

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The information available is not sufficient to evaluate Tier C, hazardous volume quantify, as required by Reference 1, Section 2.4.1.3.

Volume Assigned Value: 0

2.4.2.1.4 Area

Although soil samples collected from Source No. 2 were contaminated, it is not known if soil contamination exists between all contaminated soil sampling locations. Therefore, the area of Source No. 2 is undetermined, but greater than zero (Ref. 5, Figure 3-2).

Area Assigned Value: >0

2.4.2.1.5 Calculation of Source Hazardous Waste Quantity Value

A source hazardous waste quantity value of >0 is assigned for Source No. 2 (Ref. 1, Section 2.4.2.1.5).

Highest value assigned from Reference 1, Table 2-5: >0

42 Source Characterization

Source No. 3

2.2.1 SOURCE IDENTIFICATION

Number of source: 3

Name of source: Slag Dump Waste Pile Located in the 19th Century Operations Area

Source Type: Pile

Description and Location of Source (with reference to a map of the site):

Source No. 3 is comprised of a slag dump (waste pile) located in the 19th Century Operations Area of the Ore Knob Mine (Ref. 5, Figure 3-2) and shown on Figure 4 of this HRS documentation record. Mining activities at the 19th Century Operations Area began prior to 1860 (Refs. 31, p. 2; 34, p. 25; 40, p. 44) and continued until about the mid-1950s when the mill area was opened west of the 19th Century Operations Area (Refs. 5, pp. 3, 9, 10; 40, p. 44). Mining activities included roasting sorted ores and dressed fines, fusion in a shaft furnace for mattes, roasting the mattes in piles, fusion in a shaft furnace for black or pig copper concentrated or double matte, treatment of the salamanders, and fining and refining (Ref. 31, p. 3). During the early years of operation, the mine was one of the largest copper ore mines in the area (Ref. 31, p. 3). After the 1950s mill was opened, shaft mining was employed to remove the ore from the mine (Ref. 42, p. 6). As a result of these extraction practices, mine portals (adits) can be found on the site where miners entered the ore body horizontally from the surface. Vertical shafts were developed where the miners followed the deposit downward and removed the ore. Rock materials associated with the ore deposit were sometimes brought to the surface and simply dumped near the openings, and can be found surrounding the existing vertical shaft (Ref. 42, p. 6).

During the 2007 ESI, several piles including slag, waste rock dumps, roaster waste, and crushed and oxidized wastes were observed in the 19th Century Operations Area. These piles primarily were located in areas near mine shafts and adits, the former roaster area, and in the vicinity of the former engine shaft (Ref. 7, Book 4, pp. 12, 13, 18, 25, 26, Book 5, p. 5). A waste sample was collected from a slag dump waste pile. Table 10 provides the description of the sampling location where the Source No. 3 waste sample was collected and the list of contaminants detected in the sample (Ref. 5, Table 3-5; Appendix E, pp. E-45 and E-46). The soil sampling locations are shown on Figure 4 of this HRS documentation record.

43 Source Characterization

Source No. 3

TABLE 10: Summary of Waste Samples from Source No. 3 Slag Dump Waste Pile Located in the 19th Century Operations Area Sample Depth Hazardous Station Sample Sample (inches Substances ID Description of Location Description Date bgs) Detected References Slag dump located east of the former roaster 5, Figures 2-2 and 3-2, Table 3-5 and Copper, area about 190 feet east of road to the main Sand with slag Appendix E, pp. E-45, E-46; 7, Book 4, OK558 7/18/2007 0 – 12 manganese, tailings pile and about 260 feet north- fragments p. 18; see Table 11 of this silver, zinc northeast the former smelter. documentation record

Notes: bgs Below ground surface ID Identification No. Number OK Ore Knob Mine

44 Source Characterization

Source No. 3

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

The waste sample listed in Table 11 was collected from a slag dump (pile) that comprises Source No. 3 in the 19th Century Operations Area. The waste sample was collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5) The concentrations of metals detected in the waste sample were compared to concentrations of metals in background soil samples to demonstrate an increase of metals in Source No. 3. The concentrations of metals detected in Source No. 3 waste sample greater than three times the background or above the detection limit if not detected in the background sample are considered to be above naturally occurring concentrations of metals or significantly above background. Table 11 summarizes only the metals and concentrations detected significantly above background, with the consideration of data qualifiers. Table 12 summarizes the concentrations of metals detected in the background soil samples. Only the greatest concentration of each analyte from the background samples is listed in Table 12. Background soil samples were collected in areas with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area. Background soil samples consist primarily of moderate brown to moderate yellowish brown silty sand with fragments of schist and quartzite. Samples were collected either from 0 to 6 inches or 0 to 12 inches in depth. All soil samples were collected using hand augers (Ref. 5, p. 27).

The waste sample listed in Table 11 is a grab sample that was collected from a slag dump located in the 19th Century Operations Area (Refs. 5, p. 15, Figure 3-2, Table 3-5; 7, Books 4 and 5). The waste and background soil samples were collected in accordance with the EPA Region 4, SESD operating procedures SESDPROC-302-R0 and the final sampling plan (Refs. 5, pp. 14, 20, 21; 16, p. 13; 51). The chain of custody records and traffic reports are contained in Reference 19 and sample delivery groups are contained in Reference 8. The samples were analyzed under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific adjusted CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). Field sample data sheets are contained in Reference 7, Books 4 and 5. The waste and background soil sampling locations are shown on Figure 4 of this HRS documentation record.

45 Source Characterization

Source No. 3

TABLE 11: Analytical Results for Source No. 3

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 14,000J (14,000) 6, p. 72; 7, Book 4, p. 18; 19, p. 7; 22, p. OK558-WA-001 Copper 13 mg/kg mg/kg 9 OK558-WA-001 Manganese 7,100 mg/kg 8.0 mg/kg 6, p. 72; 7, Book 4, p. 18; 19, p. 7 OK558-WA-001 Silver 4.2 mg/kg 1.1 mg/kg 6, p. 72; 7, Book 4, p. 18; 19, p. 7 3,900J (3,900) 6, p. 72; 7, Book 4, p. 18; 19, p. 7; 22, p. OK558-WA-001 Zinc 32 mg/kg mg/kg 9

Notes: ( ) Concentration was adjusted in accordance with References 8, 10, 12, and 22 as a conservative measure to illustrate the relative increase of hazardous substances over those in native soil levels ID Identification number J Estimated concentration. While quantitation may be estimated, the presence of the substance is not in doubt. mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob Mine Site WA Waste sample

46 Source Characterization

Source No. 3

TABLE 12: Background Soil Sample Analytical Results for Comparison to Source No. 3 Waste Sample Results Hazardous Hazardous Substance Sample ID Substance Concentration MRL References

79J (96.38) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Copper 3.1 mg/kg mg/kg 12; 22, p. 4 OK501-SL-001 Manganese 420 mg/kg 1.9 mg/kg 6, p. 98; 7, Book 5, pp. 1, 2; 19, p. 10 0.79J (1.37) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Silver 1.3 mg/kg mg/kg 12; 22, p. 5 120J (180) 6, p. 131; 7, Book 5, pp. 10, 11; 19, p. OK502-SL-001 Zinc 7.5 mg/kg mg/kg 12; 22, p. 5

Notes:

47 Source Characterization

Source No. 3

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

The waste sample collected from Source No. 3 contains copper, manganese, silver, and zinc (Ref. 6, pp. 65, 72, 73, 99, 125) (also see Table 11 of this HRS documentation record). Source No. 3 is a slag dump waste pile located in the 19th Century Operations Area (Ref. 5, Figures 2-2, 3-2). Analytical results of sediment samples collected from drainage routes that receive runoff from Source No. 3 indicate that hazardous substances have migrated from Source No. 3 (Refs. 5, Figure 3-2; 6, pp. 105 and 132). During the 2007 sampling event, soil samples collected from drainage areas in the 19th Century Operations Area contained the same hazardous substances as detected in Source No. 3 (Refs. 6, pp, 122, 127, 128; 7, Book 5, pp. 5, 6, 8). Surface water runoff from all areas in the 19th Century Operations Area, including Source No. 3, flow to Ore Knob Branch (Refs. 5, Appendix E, p. E-1; 39, p. 5). A containment factor value of 10 as noted in Table 13 was assigned for the surface water migration pathway (Ref. 1, Section 4.1.2.1.2.1.1).

TABLE 13: Containment Factors for Source No. 3 Containment Containment Description Factor Value Reference Gas release to air NS NA Particulate release to air NS NA Release to ground water NS NA Release via overland migration and/or flood: Neither of the following is present: (1) maintained 1, Section 4.1.2.1.2.1.1; 5, Figures engineered cover, or (2) functioning and maintained 10 2-2, 3-2; 5, Appendix E, p. E-1. run-on control system and runoff management See paragraph above. system.

Notes:

NA Not applicable NS Not scored

48 Source Characterization

Source No. 3

2.4.2.1 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Source Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, hazardous constituent quantity, as required by Reference 1, Section 2.4.2.1.1.

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B, hazardous wastestream quantity, as required by Reference 1, Section 2.4.2.1.2.

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The information available is not sufficient to evaluate Tier C, volume, as required by Reference 1, Section 2.4.2.1.3.

Volume Assigned Value: 0

2.4.2.1.4 Area

Although contamination is present at the source sample location, it is unclear if the slag wastes are continuous within the estimated pile area, thus the area of Source 3 is undetermined, but greater than zero.

Area Assigned Value: >0

2.4.2.1.5 Calculation of Source Hazardous Waste Quantity Value

A source hazardous waste quantity value of >0 is assigned for Source No. 3 (Ref. 1, Section 2.4.2.1.5).

Highest value assigned from Reference 1, Table 2-5: >0

49 Source Characterization

Source No. 4

2.2.1 SOURCE IDENTIFICATION

Number of source: 4

Name of source: Tailings Pile in the Former 1950s Mill Area

Source Type: Tailings Pile

Description and Location of Source (with reference to a map of the site):

Source No. 4 is a tailings pile located in the northern portion of the Former 1950s Mine and Mill area and covers about 2 acres (Refs. 5, p. 3, Figure 2-3; 25; 59, pp. 2, 6, 8, 10). The tailings pile was originally a tailings impoundment that was used during construction of the Former 1950s Mine and Mill in order to test the viability of the mining and milling process and to provide for interim tailings disposal (Ref. 45, p. 1). Ore beneficiation activities at the former 1950s mill area occurred around 1957 to 1962 (Ref. 5, p. 3). During operations, the ore was grinded to recover copper, gold, and silver (Ref. 42, p. 6). Further processing of the ore included froth flotation and cyanide leaching. Waste from the cyanide leaching process was discharged into a sediment pond located below the processing area (Ref. 42, p. 6). Some of the tailings generated during processing activities were disposed of in a small hollow adjacent to the processing facility (Ref. 42, p. 6). This disposal area is the location of Source No. 4, the tailings pile at the former 1950s mill (Ref. 5, Figure 2-3 Appendix E, p. E-72). The estimated area of Source No. 4, based on aerial photographs of the area and the sampling locations, is about 2 acres (Ref. 5, Figure 3-3, Appendix E, pp. E-72 through E-77). The area of Source No. 4 measured using a GIS program is about 74,092 ft2 (Ref. 25) (Also see Figure 5 of this HRS documentation record). Soil borings advanced in the tailings area indicate that at least 4 feet of tailings are located in some areas of the tailings pile at the former 1950s mill area (Refs. 5, Appendix E, pp. E-73, E-75, E-77; 7, Book 6, pp. 20, 22, 24, through 27). The waste samples collected at the various sampling stations from Source No. 4 varied in color from yellowish-orange, to grayish-white, to medium brown (Refs. 5, Appendix E, pp. E-73, E-75, E-77; 7, Book 6, pp. 20, 25). Table 14 provides the descriptions of the locations of the waste samples collected from Source No. 4 and the list of contaminants detected at each sampling location (Ref. 5, Table 3-5, Appendix E, pp. E-72 through E-77). The waste sampling locations are shown on Figure 5 of this HRS documentation record.

50 Source Characterization

Source No. 4

TABLE 14: Summary of Waste Samples from Source No. 4 Tailings Pile in the Former 1950s Former Mine and Mill Area Sample Sample Hazardous Sample Station Description of Location Description Depth Substances References Date ID (inches bgs) Detected Southwestern portion of the tailings 5, p. 33, Figures 2-3 and 3-3, Table 3-5 and Cadmium, area located north of the mill site, Appendix E, pp. E-72, E-73; 7, Book 6, p. OK452 Tailings 7/18/2007 4 – 30 copper, mercury, about 310 feet north of the former truck 26; see Table 15 of this documentation silver, zinc loading bins. record Southeastern portion of the tailings 5, p. 33, Figures 2-3 and 3-3, Table 3-5 and area north of the mill site, about 320 Appendix E, pp. E-74, E-75; 7, Book 6, p. OK453 Tailings 7/18/2007 4 – 48 Copper, mercury feet north of the former truck loading 24; see Table 15 of this documentation bins. record 5, p. 33, Figures 2-3 and 3-3, Table 3-5 and Northern portion of the tailings area Appendix E, pp. E-76, E-77; 7, Book 6, pp. OK454 north of the mill site, about 490 feet Tailings 7/18/2007 4 – 48 Copper 20, 22; see Table 15 of this documentation north of the former truck loading bins. record

Note: bgs Below ground surface ID Identification No. Number OK Ore Knob Mine

51 Source Characterization

Source No. 4

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

The waste samples listed in Table 15 were collected from the tailings waste pile, Source No. 4, in the former 1950s mill area. The waste samples were collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). The concentrations of metals detected in the waste samples were compared to concentrations of metals in native soil samples to demonstrate the relative increase of metal concentrations and availability in Source No. 4 over naturally occurring levels in native soils. Table 15 summarizes only the metals and concentrations detected significantly above background, with the consideration of data qualifiers. Table 16 summarizes the concentrations of metals detected in the native (background) soil samples. Only the greatest concentration of each analyte from the background samples is listed in Table 16. Background soil samples were collected in areas with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area. Background soil samples consist primarily of moderate brown to moderate yellowish brown silty sand with fragments of schist and quartzite. Background samples were collected from 0 to 6 inches in depth (Ref. 7, Book 6, pp. 4, 5). All soil samples were collected using hand augers (Ref. 5, p. 27).

All waste samples listed in Table 15 are grab samples that were collected from various locations throughout the former 1950s mill area (Refs. 5, p. 15, Figure 3-3, Table 3-5; 7, Book 6). The waste and background soil samples were collected in accordance with the EPA Region 4, SESD operating procedures SESDPROC-302-R0 and the final sampling plan (Refs. 5, pp. 14, 20, 21; 16, p. 13; 51). The chain of custody records and traffic reports are contained in Reference 19 and sample delivery groups are contained in Reference 8. The samples were analyzed under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific adjusted CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). Field sample data sheets are contained in Reference 7, Book 6. The waste sampling locations are shown on Figure 5 of this HRS documentation record.

52 Source Characterization

Source No. 4

TABLE 15: Analytical Results for Source No. 4

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK452-WA-001 Cadmium 11 mg/kg 0.63 mg/kg 6, p. 78; 7, Book 6, pp. 26, 27; 19, p. 8 3,800J (3,800) 6, p. 78; 7, Book 6, pp. 26, 27; 19, p. 8; OK452-WA-001 Copper 3.2 mg/kg mg/kg 22, p. 19 OK452-WA-001 Mercury 0.20 mg/kg 0.12 mg/kg 6, p. 78; 7, Book 6, pp. 26, 27; 19, p. 8 OK452-WA-001 Silver 1.7 mg/kg 1.3 mg/kg 6, p. 78; 7, Book 6, pp. 26, 27; 19, p. 8 2,500J (1,666.67) 6, p. 78; 7, Book 6, pp. 26, 27; 19, p. 8; OK452-WA-001 Zinc 7.6 mg/kg mg/kg 22, p. 20 1,200J (1,200) 6, p. 80; 7, Book 6, p. 24; 19, p. 8; 22, p. OK453-WA-001 Copper 2.8 mg/kg mg/kg 20 OK453-WA-001 Mercury 0.22 mg/kg 0.097 mg/kg 6, p. 80; 7, Book 6, p. 24; 19, p. 8 1,700J (1,700) 6, p. 82; 7, Book 6, pp. 20, 22; 19, p. 8; OK454-WA-001 Copper 2.8 mg/kg mg/kg 22, p. 20

Notes:

53 Source Characterization

Source No. 4

TABLE 16: Background Soil Sample Analytical Results for Comparison to Source No. 4 Waste Sample Results Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK402-SL-001 Cadmium 0.62UJ mg/kg 0.62 mg/kg 6, p. 12; 7, Book 6, p. 5; 19, p. 2 43J (52.46) 6, p. 12; 7, Book 6, p. 5; 19, p. 2; OK402-SL-001 Copper 3.1 mg/kg mg/kg 22, p. 12 OK400-SL-001 Mercury 0.13U mg/kg 0.13 mg/kg 6, p. 10; 7, Book 6, p. 4; 19, p. 2 OK400-SL-001 Silver 1.2U mg/kg 1.2 mg/kg 6, p. 10; 7, Book 6, p. 4; 19, p. 2

6, p. 12; 7, Book 6, p. 5; 19, p. 2; OK402-SL-001 Zinc 34J (51) mg/kg 7.4 mg/kg 22, p. 13

ID Identification number J Estimated concentration. While quantitation may be estimated, the presence of the substance is not in doubt. mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob Mine Site SL Soil sample U The analyte was not detected at or above the reporting limit. UJ Analyte was not detected at or above the reporting limit. The value (quantitation) is an estimate, but the presence of the analyte is not in doubt.

54 Source Characterization

Source No. 4

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Waste samples collected from Source No. 4 contain, cadmium, copper, mercury, selenium, silver, and zinc (Ref. 6, pp. 64, 77, 78, 80, 82) (also see Table 15 of this HRS documentation record). Source No. 4 is comprised of a tailings pile located in the northern portion of the former 1950s mill area (Ref. 5, Figure 3-3). Surface water runoff from Source No. 4 drains towards Little Peak Creek (Refs. 3; 5, Figure 3-3). Analytical results for sediment samples collected from Little Peak Creek indicate that Source No. 4 has released hazardous substances to the surface water migration pathway as documented in Section 4.0 of this HRS documentation record (Ref. 6, pp. 66, 67, 70). Runoff from Source No. 4 drains towards the northern end of the former fresh water pond located in the 1950s Mine and Mill area (Ref. 5, Figure 3-3, Table 3-5; 7, Book 6, pp. 26, 29, 31). During the 2007 ESI conducted by Black & Veatch, the dam on the north side of the former fresh water pond that discharges to Little Peak Creek was observed to be breached (Ref. 5, p. 74). Tailings were also observed in the vicinity of the dam at sampling station OK024 (Ref. 7, Book 6, p. 31). Therefore, a containment factor value of 10 as noted in Table 17 was assigned for the surface water migration pathway (Ref. 1, Section 4.1.2.1.2.1.1).

TABLE 17: Containment Factors for Source No. 4 Containment Containment Description Factor Value Reference Gas release to air NS NA Particulate release to air NS NA Release to ground water NS NA Release via overland migration and/or flood: 1, Section 4.1.2.1.2.1.1; 5, p. 74, Neither of the following is present: (1) maintained Figure 3-3; 3; 5, Figure 3-3; 7, engineered cover, or (2) functioning and maintained 10 Book 6, p. 31. See paragraph run-on control system and runoff management above. system.

Notes:

NA Not applicable NS Not scored

55 Source Characterization

Source No. 4

2.4.2.1 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Source Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, hazardous constituent quantity, as required by Reference 1, Section 2.4.2.1.1.

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B, hazardous wastestream quantity, as required by Reference 1, Section 2.4.2.1.2.

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The information available is not sufficient to evaluate Tier C, volume, as required by Reference 1, Section 2.4.2.1.3.

Volume Assigned Value: 0

2.4.2.1.4 Area

Source No. 4 is a tailings pile located at the former 1950s mill area and covers about 74,092 ft2 in area (Refs. 5, Appendix E, pp. E-72 through E-77; 25; 61) (also see Figure 5 of this HRS documentation record). The estimated area of Source No. 4 was delineated based on the locations of the waste samples collected from the pile (Refs. 5, Figure 3-3; 61).

Sum (ft2): 74,092 (Ref. 5, Figure 3-3, Appendix E, pp. E-72 through E-77; 25; 61). Equation for Assigning Value (Ref. 1, Table 2-5): ft2/13 Therefore, 74,092 ft2 ÷ 13 = 5,699.384 Area Assigned Value: 5,699.384

2.4.2.1.5 Calculation of Source Hazardous Waste Quantity Value

The source HWQ value for Source No. 4 is 5,699.384 (Ref. 1, Section 2.4.2.1.5).

Highest value assigned from Reference 1, Table 2-5: 5,699.384

56 Source Characterization

Source No. 5

2.2.1 SOURCE IDENTIFICATION

Number of source: 5

Name of source: Multiple Areas of Contaminated Soil in the Former 1950s Mill Area

Source Type: Contaminated Soil

Description and Location of Source (with reference to a map of the site):

Source No. 5 is an area of contaminated soil located in the Former 1950s Mine and Mill area at Ore Knob (Ref. 25). The general vicinity of the Former 1950s Mill area is about 15 acres in area (Refs. 5, p. 3, Figure 2-3; 25, 59, pp. 2, 6, 8, 10). Ore beneficiation activities at the former 1950s mill area occurred around 1957 to 1962 (Ref. 5, p. 3). At the time of the 2007 ESI sampling event, features of the former 1950s mill included derelict ore bins, concrete mill foundations, a transformer building, other ruins, and a tailings area (Ref. 5, p. 3, Figure 2-3). A small sawmill was operating in this area at the time of the ESI sampling event. The buildings in the former 1950s mill area appeared to be constructed on fill material that is believed to be from mining operations (Ref. 5, p. 3, Appendix E, pp. E-53 through E-71). During the 2007 ESI sampling event, soil samples were collected under building foundations and ore bins, and from various locations around buildings located throughout the former 1950s mill area (Ref. 5, Appendix E, pp. E-53 through E-71). Table 18 provides the descriptions of the locations of the soil samples collected from Source No. 5 and the list of contaminants detected at each sampling location. Because the samples were collected from various areas throughout the Former 1950s Mill area, and because the sample locations drain into the same surface water bodies, and contained the same hazardous substances, the areas of contaminated soil were combined into one source. Observations of the soil sampling locations and samples indicate that the soils were impacted by mining activities. The samples are stained (Ref. 5, Appendix E, pp. E-53 through E-59). The soil sampling locations are shown on Figure 6 of this HRS documentation record.

57 Source Characterization

Source No. 5

record 5, Figures 2-3 and 3-3, Table Adjacent to the northeast corner of the 3-5 and Appendix E, pp. E- OK412 transformer building. Silty sand 7/17/2007 0 – 6 Copper, mercury 54; 7, Book 6, p. 2; see Table 21 of this documentation record 5, Figures 2-3 and 3-3, Table Beside a foundation pier of the ball mill 3-5 and Appendix E, pp. E- OK413 structure, about 40 feet north of the eastern Clay and silt 7/18/2007 0 – 4 Mercury 55; 7, Book 6, p. 18; see former fine ore bin. Table 21 of this documentation record Northwestern corner of the former flotation 5, p, 36, Figures 2-3 and 3-3, plant foundation, about 12 feet off the Arsenic, chromium, Table 3-5 and Appendix E, Clay, sand, OK414 southwestern corner of the former truck 7/18/2007 0 – 18 copper, mercury, nickel, pp. E-56, E-57; 7, Book 6, p. silt loading bins where material has collapsed or selenium, silver, zinc 14; see Table 21 of this has been pushed into a sump. documentation record 5, p. 36, Figures 2-3 and 3-3, Under the conveyor system foundation, about Table 3-5 and Appendix E, Fine grain Copper, mercury, OK415 12 feet west of the former crusher house 7/17/2007 0 – 18 pp. E-58; 7, Book 6, p. 6; see ore selenium, silver, zinc foundation. Table 21 of this documentation record 5, Figures 2-3 and 3-3, Table Low-lying drainage point beside the 3-5 and Appendix E, pp. E- Sand with Copper, mercury, silver, OK417 northeastern corner of the former truck 7/17/2007 0 – 6 60; 7, Book 6, p. 9; see Table some gravel zinc loading bins. 21 of this documentation record

58 Source Characterization

Source No. 5

TABLE 18: Summary of Soil Samples from Source No. 5 Multiple Areas of Contaminated Soil in the Former 1950s Mine and Mill Area Station Sample Sample Sample Depth Hazardous Substances ID Description of Location Description Date (inches bgs) Detected References About 120 feet east of the tailings area north 5, Figures 2-3 and 3-3, Table of the former mill site; about 130 feet west of Tailings 3-5 and Appendix E, pp. E- the southern end of the former freshwater OK422 (clay and 7/19/2007 0 – 6 Mercury, selenium 64; 7, Book 6, p. 30; see pond in a well-defined drainage path trending silt) Table 21 of this northeast from the southern one-third of the documentation record tailings area. 5, Figures 2-3 and 3-3, Table In a drainage path about 100 feet west of the Tailings 3-5 and Appendix E, pp. E- former fresh water pond; downhill and east of OK423 (sand with 7/18/2007 0 – 12 Mercury, selenium, zinc 65; 7, Book 6, p. 23; see the northern end of the tailings area located in clay) Table 21 of this the northern portion of the mill site. documentation record 5, Figures 2-3 and 3-3, Table 3-5 and Appendix E, pp. E- About 180 feet south of the southern end of OK424 Tailings 7/19/2007 0 – 18 Copper, mercury 66; 7, Book 6, p. 31; see the former freshwater pond. Table 21 of this documentation record 5, Figures 2-3 and 3-3, Table Within the former freshwater pond, near the Tailings 3-5 and Appendix E, pp. E- center (north-south), about 50 feet east of the (sand and 7/19/2007 0 – 6 Cadmium, copper 67; 7, Book 6, p. 29; see OK425 western margin. silt) Table 21 of this documentation record Notes: bgs Below ground surface ID Identification No. Number OK Ore Knob Mine

59 Source Characterization

Source No. 5

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

Background Samples

The background soil samples listed in Table 19 were collected to enable comparison of naturally occurring metals levels in native soils to soil samples collected from multiple areas of contaminated soil located in the Former 1950s Mill area (Source No. 5) (Refs. 5, pp. 15, 16, Figure 3-3, Table 3-5; 7, Book 6, pp. 3, 4, 5). The background soil samples were collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). Background soil samples were collected in areas with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area. Background soil samples consist primarily of moderate brown to moderate yellowish brown silty sand with fragments of schist and quartzite. Samples were collected either from 0 to 6 inches or 0 to 12 inches in depth. All soil samples were collected using hand augers (Ref. 5, p. 27).

The background and source soil samples were collected using the same collection methods in accordance with the SESD operating procedures SESDPROC-300-R0 and the final sampling plan (Refs. 5, pp. 14 to 16, 20, 21; 17, p. 16; 51). All soil samples listed in Tables 18 and 19 are grab samples (Ref. 5, p. 15, Figure 3-3, Table 3-5; 7, Book 6). The chain of custody records and sample delivery groups are contained in References 19 and 8, respectively. The background and source soil samples were analyzed using the same methods under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed both the background and source soil analytical data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15).

As documented in Tables 18 and 19, the background and source soil samples were collected within the same time frame. The description of the soil samples collected from Source No. 5 in Table 18 indicates that the Source No. 5 soil samples were collected from areas disturbed and impacted by mining activities. The samples contain mine tailings. The samples were collected from locations near mining activities such as transformer buildings, ore bins, loading binds, conveyer system, electric shop, and tailings areas (see Table 18 of this HRS documentation record). The soils are stained (Ref. 5, Appendix E, pp. E-53 to E- 67). The background soil samples were collected from locations with little evidence of recent or historic disturbance to determine baseline soil composition in the Ore Knob area (Ref. 5, p. 27). The background soil sample metal concentrations represent native soil metal concentrations because the background sampling locations were not impacted by mining activities. Both the background and the source soil samples were collected from the Watauga-Fannin-Chandler soil series. This series is described as sloping to very steep, well drained and somewhat excessively drained soils that have a loamy subsoil (Ref. 57, General Soil Map, Soil Legend).

The concentrations of metals detected in the background soil samples are summarized in Table 19. The background soil sample analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific adjusted CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). These adjusted detection limits are cited in Table 19. Field sample data sheets for the background soil samples are contained in Reference 7, Book 6. Only the greatest concentration of each analyte from the three background samples is listed in Table 20. The chain of custody records and traffic reports are contained in Reference 19 and sample delivery groups are contained in Reference 8. The soil sampling locations are shown on Figure 6 of this HRS documentation record.

60 Source Characterization

Source No. 5

TABLE 19- Background Soil Sample Locations and Descriptions Sample Depth Sample Date Sample ID Description of Location Sample Description (inches bgs) References Former Mill Site area. Sample collected about 70 feet north of road that leads to the transformer 5, p. 9, Appendix E, p. E-48; OK400-SL-001 Fine sand and silt 0 – 6 7/17/2007 building, about 200 feet west of the ball mill 7, Book 6, p. 4 foundation. Background sample. Former Mill Site area. Sample collected about 70 5, p. 9, Appendix E, p. E-49; OK401-SL-001 feet southwest of the transformer building. Sand and silt 0 – 6 7/17/2007 7, Book 6, p. 3 Background sample. Former Mill Site area. Sample collected about 50 feet southwest of the road leading to the transformer building, about 150 feet south of the hoist and OK402-SL-001 compressor building foundation. If heading Silty sand 0 – 6 7/17/2007 5, p. 9; 7, Book 6, p. 5 northwest along this road, the location is beyond the power-line easement, uphill in the woods. Background sample.

Notes:

ID Identification number OK Ore Knob Mine Site SL Soil sample

61 Source Characterization

Source No. 5

TABLE 20: Analytical Results for Background Soil Samples for Comparison to Source No. 5 Soil Sample Results Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 16J (20.64) 6, p. 10; 7, Book 6, p. 4; 19, p. 2; OK400-SL-001 Chromium 1.2 mg/kg mg/kg 22, p. 9 OK400-SL-001 Mercury 0.13U mg/kg 0.13 mg/kg 6, p. 10; 7, Book 6, p. 4; 19, p. 2 6.2J (8.37) 6, p. 10; 7, Book 6, p. 4; 19, p. 2; OK400-SL-001 Nickel 4.8 mg/kg mg/kg 22, p. 10 OK400-SL-001 Silver 1.2U mg/kg 1.2 mg/kg 6, p. 10; 7, Book 6, p. 4; 19, p. 2 1.8J (3.13) 6, p. 11; 7, Book 6, p. 3; 19, p. 2; OK401-SL-001 Arsenic 1.2 mg/kg mg/kg 22, p. 11 OK402-SL-001 Cadmium 0.62UJ mg/kg 0.62 mg/kg 6, p. 12; 7, Book 6, p. 5; 19, p. 2 43J (52.46) 6, p. 12; 7, Book 6, p. 5; 19, p. 2; OK402-SL-001 Copper 3.1 mg/kg mg/kg 22, p. 12 OK402-SL-001 Selenium 4.3UJ mg/kg 4.3 mg/kg 6, p. 12; 7, Book 6, p. 5; 19, p. 2 6, p. 12; 7, Book 6, p. 5; 19, p. 2; OK402-SL-001 Zinc 34J (51) mg/kg 7.4 mg/kg 22, p. 13

Notes:

62 Source Characterization

Source No. 5

Contaminated Samples

The soil samples listed in Table 21 were collected from multiple areas of contaminated soil located in the Former 1950s Mill area (Source No. 5). The soil samples were collected by Black & Veatch during the July 2007 ESI sampling event (Ref. 5, p. 1, Table 3-5). All soil samples listed in Table 21 are grab samples that were collected from various locations throughout Source No. 5 (Refs. 5, pp. 15 and 16, Figure 3-3, Table 3-5; 7, Book 6). The chain of custody records and traffic reports are contained in Reference 19 and the sample delivery groups are contained in Reference 8. The samples were analyzed under the EPA CLP, for total metals and cyanide analysis using the CLP SOW ILM05.3/ILM05.4 (Refs. 5, p. 22; 6, p. 1; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, pp. 2, 3, 4). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The analytical data sheets are contained in Reference 6. The minimum reporting limits on the analytical data sheets are the sample-specific and analyte-specific adjusted CLP CRQLs that correspond to the lowest quantitative point on the calibration curve and are adjusted for the amount of sample prepared, and any dilutions performed, as well as the percent moisture of soil samples (Ref. 11). Field sample data sheets are contained in Reference 7, Book 6. Because Source No. 5 is comprised of multiple areas of contaminated soil, the concentrations of hazardous substances detected in Source No. 5 were compared to background. The concentrations of metals detected in Source No. 5 soil samples that are greater than three times the concentrations in the background samples or above the minimum reporting limits if not detected in the background samples are considered to be elevated (Ref. 1, Table 2-3; 11). The background samples are presented in Tables 19 and 20 of this HRS documentation record. Estimated concentrations of hazardous substances in Source No. 5 were adjusted in accordance with References 10 and 12. The calculations and bias directions for the estimated concentrations are presented in Reference 22. The soil sampling locations are shown on Figure 6 of this HRS documentation record.

TABLE 21: Analytical Results for Source No. 5

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK411-SL-001 Mercury 0.14 mg/kg 0.11 mg/kg 6, p. 13; 7, Book 6, p. 1; 19, p. 3 280J (280) 6, p. 14; 7, Book 6, p. 2; 19, p. 3; 22, OK412-SL-001 Copper 2.7 mg/kg mg/kg p. 14 OK412-SL-001 Mercury 0.18 mg/kg 0.10 mg/kg 6, p. 14; 7, Book 6, p. 2; 19, p. 3 OK413-SL-001 Mercury 0.28 mg/kg 0.12 mg/kg 6, p. 58; 7, Book 6, p. 18; 19, p. 6 6, p. 50; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001 Arsenic 14J (14) mg/kg 1.7 mg/kg 22, p. 14 1,300J (1,300) 6, p. 50; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001 Copper 4.2 mg/kg mg/kg 22, p. 14 OK414-SL-001 Mercury 0.16 mg/kg 0.16 mg/kg 6, p. 50; 7, Book 6, p. 14; 19, p. 6 6, p. 50; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001 Selenium 77J (77) mg/kg 5.9 mg/kg 22, p. 14

63 Source Characterization

Source No. 5

TABLE 21: Analytical Results for Source No. 5

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References 350J (350) 6, p. 50; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001 Zinc 10 mg/kg mg/kg 22, p. 14 6, p. 52; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001D Arsenic 28J (28) mg/kg 1.6 mg/kg 22, p. 15 OK414-SL-001D Cadmium 19 mg/kg 0.80 mg/kg 6, p. 52; 7, Book 6, p. 14; 19, p. 6 OK414-SL-001D Chromium 64 mg/kg 1.6 mg/kg 6, p. 52; 7, Book 6, p. 14; 19, p. 6 OK414-SL-001D Copper 7,700 mg/kg 4.0 mg/kg 6, p. 52; 7, Book 6, p. 14; 19, p. 6 6, p. 52; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001D Nickel 68J (68) mg/kg 6.4 mg/kg 22, p. 15 6, p. 52; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001D Selenium 65J (65) mg/kg 5.6 mg/kg 22, p. 15 OK414-SL-001D Silver 4.1 mg/kg 1.6 mg/kg 6, p. 52; 7, Book 6, p. 14; 19, p. 6 1,600J (1,600) 6, p. 52; 7, Book 6, p. 14; 19, p. 6; OK414-SL-001D Zinc 9.6 mg/kg mg/kg 22, p. 15 510J (510) 6, p. 33; 7, Book 6, p. 6; 19, p. 4; 22, OK415-SL-001 Copper 2.9 mg/kg mg/kg p. 15 OK415-SL-001 Mercury 0.23 mg/kg 0.12 mg/kg 6, p. 33; 7, Book 6, p. 6; 19, p. 4 13J (5.46) 6, p. 33; 7, Book 6, p. 6; 19, p. 4; 22, OK415-SL-001 Selenium 4.1 mg/kg mg/kg p. 15 OK415-SL-001 Silver 1.4 mg/kg 1.2 mg/kg 6, p. 33; 7, Book 6, p. 6; 19, p. 4 230J (153.33) 6, p. 33; 7, Book 6, p. 6; 19, p. 4; 22, OK415-SL-001 Zinc 7.0 mg/kg mg/kg p. 16 OK416-SL-001 Mercury 0.16 mg/kg 0.12 mg/kg 6, p. 56; 7, Book 6, p. 21; 19, p. 6 9,600J (9,600) 6, p. 32; 7, Book 6, p. 9; 19, p. 4; 22, OK417-SL-001 Copper 7.1 mg/kg mg/kg p. 16 OK417-SL-001 Mercury 0.23 mg/kg 0.15 mg/kg 6, p. 32; 7, Book 6, p. 9; 19, p. 4 OK417-SL-001 Silver 2.2 mg/kg 1.4 mg/kg 6, p. 32; 7, Book 6, p. 9; 19, p. 4 490J (326.67) 6, p. 32; 7, Book 6, p. 9; 19, p. 4; 22, OK417-SL-001 Zinc 8.6 mg/kg mg/kg p. 17 OK422-SL-001 Mercury 0.31 mg/kg 0.13 mg/kg 6, p. 103; 7, Book 6, p. 30; 19, p. 11 14J (5.88) 6, p. 103; 7, Book 6, p. 30; 19, p. 11; OK422-SL-001 Selenium 4.6 mg/kg mg/kg 22, p. 17 OK423-SL-001 Mercury 0.13 mg/kg 0.12 mg/kg 6, p. 76; 7, Book 6, p. 23; 19, p. 8

64 Source Characterization

Source No. 5

TABLE 21: Analytical Results for Source No. 5

Hazardous Hazardous Substance Sample ID Substance Concentration MRL References OK423-SL-001 Selenium 28 mg/kg 4.1 mg/kg 6, p. 76; 7, Book 6, p. 23; 19, p. 8 200J (200) 6, p. 76; 7, Book 6, p. 23; 19, p. 8; OK423-SL-001 Zinc 7.0 mg/kg mg/kg 22, p. 17 1,300J (1,300) 6, p. 101; 7, Book 6, p. 31; 19, p. 10; OK424-SL-001 Copper 3.1 mg/kg mg/kg 22, p. 18 OK424-SL-001 Mercury 0.13 mg/kg 0.11 mg/kg 6, p. 101; 7, Book 6, p. 31; 19, p. 10 OK425-SL-001 Cadmium 3.9 mg/kg 1.5 mg/kg 6, p. 91; 7, Book 6, p. 29; 19, p. 10 480J (480) 6, p. 91; 7, Book 6, p. 29; 19, p. 10; OK425-SL-001 Copper 7.7 mg/kg mg/kg 22, p. 18

Notes:

65 Source Characterization

Source No. 5

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Soil samples collected from Source No. 5 contain arsenic, cadmium, chromium, copper, mercury, nickel, selenium, silver, and zinc (Ref. 6) (also see Table 21 of this HRS documentation record). Source No. 5 is comprised of multiple areas of contaminated soil located throughout the Former 1950s Mill area (Ref. 5, pp. 3, 15, 16, Figures 2-3, 3-3). Surface water runoff from Source No. 5 drains towards Little Peak Creek. A former freshwater pond is located in the area of Source No. 5. Drainage from this former freshwater pond also enters Little Peak Creek. A dam on the northern side of the former pond was breached during the 2007 ESI sampling event (Ref. 5, p. 3, Figures 2-3, 3-3). Analytical results for sediment samples collected from Little Peak Creek downstream of the breached dam indicate that Source No. 5 has released hazardous substances to the surface water migration pathway as documented in Section 4.0 of this HRS documentation record (Ref. 6, pp. 66, 67, 70) (also see Table 28 of this HRS documentation record). Therefore, a containment factor value of 10 as noted in Table 22 was assigned for the surface water migration pathway (Ref. 1, Section 4.1.2.1.2.1.1).

TABLE 22: Containment Factors for Source No. 5 Containment Containment Description Factor Value Reference Gas release to air NS NA Particulate release to air NS NA Release to ground water NS NA Release via overland migration and/or flood: Neither of the following is present: (1) maintained 1, Section 4.1.2.1.2.1.1; 5, p. 3, engineered cover, or (2) functioning and maintained 10 Figures 2-3 and 3-3. See paragraph run-on control system and runoff management above. system.

Notes:

NA Not applicable NS Not scored

66 Source Characterization

Source No. 5

2.4.2.1 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Source Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, hazardous constituent quantity, as required by Reference 1, Section 2.4.2.1.1.

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B, hazardous wastestream quantity, as required by Reference 1, Section 2.4.2.1.2.

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The information available is not sufficient to evaluate Tier C, volume, as required by Reference 1, Section 2.4.2.1.3.

Volume Assigned Value: 0

2.4.2.1.4 Area

Although soil samples collected from Source No. 5 were contaminated, it is not known if soil contamination exists between all contaminated soil sampling locations. Therefore, the area of Source No. 5 is undetermined, but greater than zero (Ref. 5, Figure 3-2).

Area Assigned Value: >0

2.4.2.1.5 Calculation of Source Hazardous Waste Quantity Value

A source hazardous waste quantity value of >0 is assigned for Source No. 5 (Ref. 1, Section 2.4.2.1.5).

Highest value assigned from Reference 1, Table 2-5: >0

67 Source Characterization

SUMMARY OF SOURCE DESCRIPTIONS

TABLE 23: Summary of Source Descriptions

Containment Factor Value by Pathway Source Surface Source Hazardous Water Air Hazardous Constituent Ground Overland/ Waste Quantity Water Flood Gas Particulate Source Quantity Complete? (Ref. 1, (Ref. 1, (Ref. 1, (Ref. 1, No. Value (Yes/No) Table 3-2) Table 4-2) Table 6-3) Table 6-9)

1 67,024.23 No NS 10 NS NS

2 >0 No NS 10 NS NS

3 >0 No NS 10 NS NS

4 5,699.384 No NS 10 NS NS

5 >0 No NS 10 NS NS

Total 72,723.614

Notes:

NS Not scored

The hazardous waste quantity factor value for Source Nos. 1 through 5 is 10,000.

Reference 1, Table 2-6: 10,000

68 Source Characterization

Description of Other Possible On-Site Sources

Other possible on-site sources identified during previous investigations at Ore Knob are discussed below:

• After the 1950s Mine and Mill was opened, shaft mining was employed to remove the ore from the mine (Ref. 42, p. 6). As a result of these extraction practices, mine portals (adits) can be found on the site where the miners entered the ore body horizontally from the surface. Historical mapping indicates that five horizontal adits are located in a small outcrop area above the tailings impoundment (Ref. 42, p. 13). During a U.S. Army Corps of Engineers investigation, four of the five adits were located (Ref. 42, p. 13). These adits discharge low pH ground water seepage to nearby surface water bodies (Refs. 3; 5, Figures 2-2, 3-2; 39, p. 5). During reclamation activities conducted during the early 1990s, the ALDs were constructed at the mouths of the adits to treat the water that discharges from the mine adits (Ref. 42, p. 13). The pH of the discharges increased; however, low pH water continues to discharge from the adits (Ref. 39, pp. 5, 6). The outlets of two ALDs can still be seen and the discharges from these drains appear to have improved water quality with a pH of 5 (Refs. 42, p. 13). Iron and aluminum flocculates appear immediately downstream from the ALDs, and the adit discharges after several hundred yards has low acidity (field measured at 60 milligrams per liter (mg/l) as CaCO3). Discharges from the ALDs later mix with impacted water from a third adit as well as un-impacted water from a small tributary farther downstream and then flow onto the tailings pile (Ref. 42, pp. 13, 14).

• Multiple waste piles including waste rock dumps, slag piles and dumps, roaster waste, and crushed and oxidized wastes are located throughout the 19th Century Operations Area at Ore Knob (Ref. 5, Figure 3-2). Mining activities Ore Knob began prior to 1860 at the 19th Century Operations Area (Refs. 31, p. 2; 34, p. 25; 40, p. 44) and continued intermittently until about the mid-1950s when the Former 1950s Mine and Mill area was opened west of the 19th Century Operations Area (Refs. 5, pp. 3, 9, 10; 40, p. 44). Mining activities included roasting sorted ores and dressed fines, fusion in a shaft furnace for mattes, roasting the mattes in piles, fusion in a shaft furnace for black or pig copper concentrated or double matte, treatment of the salamanders, and fining and refining (Ref. 31, p. 3). During the early years of operation, the mine was one of the largest copper ore mines in the country (Ref. 31, p. 3). After the 1950s Mine and Mill was opened, shaft mining was employed to remove the ore from the mine (Ref. 42, p. 6). As a result of these extraction practices, mine portals (adits) can be found on the site where the miners entered the ore body horizontally from the surface. Vertical shafts were developed where the miners followed the deposit downward and removed the ore. Rock materials associated with the ore deposit were sometimes brought to the surface and simply dumped near the openings, and can be found surrounding the existing vertical shaft (Ref. 42, p. 6).

During the 2007 ESI, several of the piles mentioned above were observed and sampled. These piles primarily were located in areas near mine shafts and adits, the former roaster area, and in the vicinity of the former engine shaft (Ref. 7, Book 4, pp. 12, 13, 25, 26, Book 5, p. 3). Analytical results of samples collected from various piles of waste rock, slag pile, and roaster wastes indicated the presence of hazardous substances including copper, mercury, lead, selenium, silver, and zinc (Ref. 6, pp. 65, 73, 99, 127 and 133). These hazardous substances were also detected in the sources evaluated for this HRS documentation record as presented in Tables 2, 8, 11, 15, and 21.

69 Source Characterization

4.0 SURFACE WATER MIGRATION PATHWAY

4.1 OVERLAND/FLOOD MIGRATION COMPONENT - Ore Knob Branch, Peak Creek, Little Peak Creek, South Fork New River

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

Overland flow from the 19th Century Operations Area and the main tailings pile, located in the eastern portion of the Ore Knob property, is directed towards Ore Knob Branch. The headwaters of Ore Knob Branch originates as seepage from several mine adits, which have been covered and fitted with ALDs to treat acid mine drainage (Refs. 5, Appendix E, p. E-1; 39, p. 5). During the 2007 ESI, two seepage channels were observed. The first seepage channel is formed of limestone cobbles coated with milky white precipitates and the second seepage channel did not have a limestone substrate, but was coated with orange mineral deposits (Ref. 5, Appendix E, pp. E-1, E-2). The two seepage channels merge to form the upper perennial reach of Ore Knob Branch (headwaters of Ore Knob Branch) (Ref. 5, Figures 3-2 and 3- 4). The creek then flows through a wooded area about 0.2 mile in a bermed ditch reaching the main tailings pile (Ref. 5, Appendix E, p. E-119). A pipe located near station OK006 conveys water underneath the main tailings pile (Ref. 5, Figure 3-4, Appendix E, p. E-116). The pipe discharges below the main tailings pile dam at the settling pond and into Ore Knob Branch (Ref. 5, Figure 3-4, Appendix E, p. E-114). The distance from the beginning of the headwaters of Ore Knob Branch to Ore Knob Branch below the settling pond is about 0.61 mile (Refs. 3; 25).

Ore Knob Branch, below the main tailings pile, flows about 0.86 mile and joins Peak Creek (Refs. 3; 5, p. 74). During the 2007 ESI, orange stained sediment was observed at the confluence of Ore Knob Branch and Peak Creek as well as on the banks of Peak Creek directly upstream and downstream of the confluence (Ref. 5, Appendix E, pp. E-129, E-165). Peak Creek (from the location where Ore Knob Branch ends) flows in a northwesterly direction for about 2.77 miles and enters the South Fork New River (Ref. 3). The South Fork New River flows in a north-northwesterly direction for about 11.37 miles, completing the 15-mile target distance limit (TDL) from this portion of the Ore Knob property (Ref. 3). The flow rate of Ore Knob Branch upstream of the confluence with Peak Creek is about 0.4 cubic feet per second (cfs) (Ref. 5, Table 3-4). The flow rate of Peak Creek measured downstream of the confluence with Ore Knob Branch and upstream of the confluence with Little Peak Creek is about 7.8 cfs. The flow rate of Peak Creek downstream of the confluence with Little Peak Creek is about 12 cfs (Ref. 5, Table 3- 4). The flow rate of the South Fork New River directly downstream of the confluence with Peak Creek is about 171 cfs (Ref. 5, Table 3-4). The average flow rate for the South Fork New River near Jefferson, North Carolina from water years 1925 to 2007 is 427.3 cfs (Ref. 26, pp. 1 through 3). Long term flow rate data from the USGS is not available for Ore Knob Branch and Peak Creek.

Overland flow from the Former 1950s Mine and Mill area, located in the western portion of the Ore Knob property, is directed towards Little Peak Creek. North of the Former Mill Area, Little Peak Creek was dammed to form a small impoundment (referred to as the freshwater pond) (Ref. 5, Figure 3-3, Appendix E, pp. E-139, E-140, E-148). The dam of the freshwater pond is breached and no longer impounds significant amounts of water (Ref. 5, p. 74, Appendix E, pp. E-139, E-140, E-148). Little Peak Creek flows about 2.17 miles before joining Peak Creek. Peak Creek (from the location where Little Peak Creek enters) flows about 0.33 mile before merging with the South Fork New River (Ref. 3). The South Fork New River flows in a north-northwesterly direction for about 12.5 miles, completing the 15-mile TDL for this portion of the Ore Knob property (Ref. 3). The flow rate of Little Peak Creek upstream of the confluence with Low Gap Branch is about 0.11 cfs. The flow rate of Little Peak Creek upstream of the confluence with Peak Creek is about 2.3 cfs (Ref. 5, Table 3-4). Long term flow rate data from the USGS is not available for Little Peak Creek. Therefore, short term flow rate data collected during the ESI is provided.

70 SW-Observed Release

Although the sources at the 19th Century Operational area and the Former 1950 Mine and Mill are physically non-contiguous, drainage from and the waste disposal practices at the sources at Ore Knob overlap and commingle within the TDL of the surface water migration pathway (Refs. 3; 45, pp. 1, 3 through 7; 25; 52). Table 24 presents the five sources evaluated for this HRS documentation record, their respective overland flow path, PPEs affected, and their respective description of flow along the TDL (Refs. 3; 25). Runoff from Source No. 1 enters PPE 1, runoff from Source Nos. 2 and 3 enter PPE 3, and runoff from Source Nos. 4 and 5 enter PPE 2. PPE 3 is the most upstream PPE (Refs. 3; 25). Runoff from Source No. 1 commingles with runoff from Source Nos. 2 and 3 at PPE 1 (Refs. 3; 25) (also see Table 24 of this HRS documentation record). Because of the distance between the PPEs, three TDLs were identified for Ore Knob (Refs. 3; 25). A description of the TDLs is provided in Table 24. TDL 3 is the most distant TDL evaluated (Refs. 3; 25). Overlapping sections of the in-water segment of the surface water migration pathway include: the entire section from PPE 1 in Ore Knob Branch (0.86 mile), along Peak Creek (2.77 miles), to the South Fork New River at TDL 2 (11.37 miles) (Refs. 3; 25). The distance from PPE 3 to TDL 3 is about 16.74 miles, which includes 0.61 mile of the headwaters of Ore Knob Branch, 0.86 mile of Ore Knob Branch, 2.77 miles of Peak Creek, and about 12.5 miles of the South Fork New River (Refs. 3; 25). In accordance with the HRS, this entire 16.74-mile length will be considered the TDL for the combined sources that drain into the watershed for this HRS documentation record (Refs. 1, Section 4.1.1.2; 60, pp. 211, 212).

71 SW-Observed Release

TABLE 24: Description of Overland and In-Water Segment of the 15-Mile Target Distance Limit Estimated PPE Source Overland Flow Description Distance to Description of In Water Segment References No. PPE Surface water runoff and seeps PPE 1 is located in Ore Knob Branch below the settling pond located from Source No. 1 flow down the north of Source No. 1. Ore Knob Branch flows for 0.86 mile into Peak 1 face of the tailings pile dam into 312 feet 1 Creek. Peak Creek flows for about 2.77 miles then joins the South Fork 3; 25 to a settling basin and then New River. The South Fork New River flows for about 11.37 miles to discharge into Ore Knob Branch. the end of the 15-mile TDL 1. Surface water runoff from Source PPE 3 is located on the eastern side of Source No. 3 at the beginning of No. 2 follows the contours of the the perennial tributary referred to as the headwaters of Ore Knob land towards a unnamed Branch. This tributary flows in a northeasterly direction for about 0.41 perennial tributary originating at mile to the southwestern end of Source No. 1. Water then enters a pipe Source No. 3. Surface water that directs drainage under Source No. 1 for about 0.2 mile then 2 runoff from the Source No. 2 soil 125 feet 3 discharges into Ore Knob Branch at PPE 1. The length of this segment 3; 25 sampling locations north of the (from PPE 3 to PPE 1) is about 0.61 mile. Ore Knob Branch flows for tributary flow south, and those 0.86 mile into Peak Creek. Peak Creek flows for about 2.77 miles then south of the tributary flow north. joins the South Fork New River. The South Fork New River flows for The tributary forms headwaters about 10.76 miles to the end of the 15-mile TDL 2. of Ore Knob Branch. PPE 3 is located on the eastern side of Source No. 3 at the beginning of the perennial tributary referred to as the headwaters of Ore Knob Branch. This tributary flows in a northeasterly direction for about 0.41 Surface water runoff from Source mile to the southwestern end of Source No. 1. Water then enters a pipe No. 3 enters the unnamed that directs drainage under Source No. 1 for about 0.2 mile then perennial tributary that forms the 3 0 feet 3 discharges into Ore Knob Branch at PPE 1. The length of this segment 3; 25 headwaters of Ore Knob Branch. (from PPE 3 to PPE 1) is about 0.61 mile. Ore Knob Branch flows for This tributary begins at the 0.86 mile into Peak Creek. Peak Creek flows for about 2.77 miles then eastern edge of Source No. 3. joins the South Fork New River. The South Fork New River flows for about 10.76 miles to the end of the 15-mile TDL 2.

72 SW-Observed Release

TABLE 24: Description of Overland and In-Water Segment of the 15-Mile Target Distance Limit Estimated PPE Source Overland Flow Description Distance to Description of In Water Segment References No. PPE Surface water runoff from Source No. 4 flows northeast overland PPE 2 is located at the headwaters of Little Peak Creek. Little Peak about 300 feet into the former Creek begins at PPE 2 and flows about 2.17 miles into Peak Creek. 4 fresh water pond. Flow 400 feet 2 3; 25 Peak Creek flows about 0.33 mile into the South Fork New River, continues for another 100 feet where the 15-mile TDL ends about 12.5 miles downstream at TDL 3. through the former pond then enters Little Peak Creek. Surface water runoff from the PPE 2 is located at the headwaters of Little Peak Creek. Little Peak northern edge of Source No. 5 Creek begins at PPE 2 and flows about 2.17 miles into Peak Creek. 5 150 feet 2 3; 25 flows about 150 feet into Little Peak Creek flows about 0.33 mile into the South Fork New River, Peak Creek. where the 15-mile TDL ends about 12.5 miles downstream at TDL 3.

Notes: No. Number PPE Probable point of entry TDL Target distance limit

73 SW-Observed Release

4.1.2.1 LIKELIHOOD OF RELEASE

4.1.2.1.1 OBSERVED RELEASE – Direct Observation

Several seeps are located in the dam on the northern end of Source No. 1. The seeps discharge into Ore Knob Branch located downstream of Source No. 1 (Refs. 3; 5, Figures 2-4 and 3-4, Appendix E, pp. E-84 through E-89); 47, pp. 1, 4 through 6). These seeps along with surface water runoff from the tailings dam, discharge to Ore Knob Branch (Refs. 5, Appendix E, pp. E-105, E-107, E-109, and E-110; 39, Appendix B, p. 20; 50, p. 6).

In addition, five horizontal adits are located in a small outcrop area above the tailings impoundment (Ref. 42, p. 13) (see Other Possible On-Site Sources section of this HRS documentation record). During reclamation activities conducted during the early 1990s, ALDs were constructed at the mouths of the adits to treat the water that discharges from the mine adits (Ref. 42, p. 13). The outlets of two ALDs can still be seen (Refs. 5, Figure 2-2, 3-2; 42, p. 13). These adits discharge low pH ground water seepage to nearby surface water bodies (Refs. 3; 5, Figures 2-2, 3-2; 39, p. 5). The pH of the discharges increased after the installation of the ALDs; however, low pH water continues to discharge from the adits (Ref. 39, pp. 5, 6). Discharges from the ALDs later mix with impacted water from a third adit as well as un- impacted water from a small tributary farther downstream and then flow onto the tailings pile (Ref. 42, pp. 13, 14).

The North Carolina Division of Water began biological assessment and monitoring activities at Ore Knob in 1991 (Ref. 39, Appendix B, pp. B2, B3). These activities were conducted to evaluate the effectiveness of planned remediation (reclamation) activities and included toxicity tests, benthic macroinvertebrate studies, fish community surveys, and chemical anaylses (Ref. 39, p. 6). North Carolina water quality standards for pH, copper, zinc, and iron had been violated at Ore Knob Branch above its confluence with Peak Creek (Ref. 39, p. 6, Appendix B, pp. B4, B6). Taxa (organism groups) in Peak Creek were rich above its confluence with Ore Knob Branch, but were poor above its confluence with the South Fork New River (Ref. 39, p. 6, Appendix B, pp. B3 through B6). Peak Creek above Ore Knob Branch had a fish community; however, the waters in Peak Creek below Ore Knob Branch were deemed unsuitable to support fisheries (Ref. 39, p. 6, Appendix B, pp. B3 through B6). Also, follow-up studies conducted in 1996 indicated that Ore Knob Branch above Peak Creek, Peak Creek below Ore Knob Branch, and Little Peak Creek were devoid of fish (Ref. 39, p. 7, Appendix B, pp. B20, B22, B24). Ore Knob Branch continued to be acidic and had high dissolved metals and a pH of 3.2 (Ref. 39, Appendix B, p. B21). The pH of Peak Creek below Ore Knob Branch ranged from 4.0 to 4.6, but recovered to about 5.5 near its confluence with the South Fork New River (Ref. 39, Appendix B, p. B20). The follow-up studies also indicated that there had been no improvement associated with the mine reclamation activities, and concluded that efforts to lessen the impact from Ore Knob had no demonstrable improvements in water quality in Peak Creek and Little Peak Creek. Also, drainage from Ore Knob continued to eliminate most of the stream fauna along 3 miles of Peak Creek and 2 miles of Little Peak Creek (Ref. 39, Appendix B, p. B21). Further, the stream bottoms of Ore Knob Branch, Little Peak Creek, and Peak Creek below Ore Knob Branch are coated with reddish-orange iron precipitate (Ref. 39, Appendix B, p. B20). This same precipitate was observed during the 2007 ESI in the tributary that forms the headwaters of Ore Knob Branch, in seeps emanating from the dam of Source No. 1 (main tailings pile), and at the confluence of Ore Knob Branch with Peak Creek (Ref. 5, Appendix E, pp, E-109, E-120, E-121, E-129).

A basinwide water quality planning report prepared by the NCDENR Division of Water Quality indicates that Ore Knob Branch (0.9 mile), Little Peak Creek (2.8 miles), and Peak Creek (2.9 miles) have habitat degradation and toxic impacts stressors that are associated with acid mine drainage (Ref. 38, pp. xv, 3, 4).

74 SW-Observed Release

4.1.2.1.1 OBSERVED RELEASE – Chemical Analysis

Background Samples

July 2007 Black & Veatch ESI Sampling Event

Sediment samples listed in Table 25 were collected by Black & Veatch during the July 2007 ESI on behalf of EPA (Refs. 5, p. 1, Figure 3-1; 7, Book 1, pp. 6, 12, Book 2, p. 24; 19, pp. 5, 7, 8). The sediment samples were collected in accordance with the SESD operating procedures SESDPROC-200-R0 and the final sampling plan (Refs. 5, pp. 14, 20; 18, pp. 14, 15, 16; 51). Background sediment samples were collected (1) upgradient of Ore Knob Branch along Peak Creek (OK015-SD-001), (2) upgradient of Little Peak Creek along Low Gap Branch (OK022-SD-001), and (3) along South Fork New River, upstream of Peak Creek and north of the Ore Knob property (OK020-SD-001) (Refs. 3; 5, Table 3-2, Figure 3-1). Sediment sample OK015-SD-001 was compared to samples collected along Ore Knob Branch and Peak Creek. Sediment sample OK022-SD-001 was compared to samples collected along Little Peak Creek. Sediment sample OK020-SD-001 was compared to samples collected along South Fork New River. Sediment samples were collected at depths ranging from 0 to 3 inches below the stream bed (bsb) (Ref. 7, Book 1, pp. 6, 12, Book 2, p. 24).

Background sediment samples were collected in accordance with the EPA Region 4, SESD operating procedure SESDPROC-200-R0 and the final sampling plan (Refs. 5, pp. 14, 20; 51). The locations of the background sediment samples listed in Table 25 are provided in Figure 3-1 of Reference 5. The traffic reports are provided in Reference 19 and sample delivery groups are contained in Reference 8.

The background sediment samples and the downstream sediment samples were collected during the same sampling event and in accordance with the same sampling procedures (Refs. 5, p. 20; 6, pp. 5, 6, 7; 7, Book 1, pp. 6, 12, 14, 27, Book 2, pp. 2, 12, 13, 16, 21, 24, 26, 28; 19, pp. 5, 7, 8, 9, 11) (also see Tables 25 and 27 of this documentation record). Also, the background sediment and downstream sediment samples were collected from similar surface water bodies with similar flow rates (Refs. 3; 5, Table 3-4; 26, pp. 1, 2, 3). The background and release sediment samples collected from the South Fork New River were primarily light and medium brown medium coarse-grained sand with small pebbles (Ref. 7, Book 1, p. 6, Book 2, pp. 2, 28). The background and release sediment samples collected from the Peak Creek and Ore Knob Branch were primarily fine brown sand, orange medium and fine sands, fine reddish brown sand, with flocculates material and some pebbles (Ref. 7, Book 1, pp. 14, , Book 2, pp. 13, 16, 24, 21, 26). Background and release sediment samples collected from Little Peak Creek and Low Gap Branch were primarily fine brown sand with pebbles, light brown medium coarse sand, minor fine sand, and red orange and brown medium sand with pebbles (Ref. 7, Book 1, p. 12, 14, Book 2, p. 13). Also, based on the soil survey of Ashe County, North Carolina, the soils in the area of Ore Knob are in the Watauga-Fannin- Chandler and Clifton-Evard-Fannin series, which are gently sloping to very steep well drained soils that have a clayey or loamy subsoil (Ref. 57, General Soil Map).

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TABLE 25: Background Sediment Sample Descriptions – July 2007 Date Sample Location Depth (bsb) References Sample ID Sampled Peak Creek Peak Creek, north and 3; 5, Figure 3-1, Table 3- OK015-SD-001 upstream of Ore Knob 2 inches 7/18/2007 2; 6, p. 6; 7, Book 2, p. property 24; 19, p. 8 Low Gap Branch Low Gap Branch, north 3; 5, Figure 3-1, Table 3- OK022-SD-001 and upstream of Ore Knob 0 to 3 inches 7/18/2007 2; 6, p. 6; 7, Book 1, p. property 12; 19, p. 7 South Fork New River South Fork New River, 3; 5, Figure 3-1, Table 3- upstream of the confluence OK020-SD-001 1.5 inches 7/17/2007 2; 6, p. 5; 7, Book 1, p. with Little Peak Creek and 6; 19, p. 5 Peak Creek

Notes: bsb Below stream bed ID Identification number OK Ore Knob SD Sediment

76 SW-Observed Release

Background Concentrations

The sediment samples listed in Table 26 were collected during the July 2007 ESI (Refs. 6, pp. 5, 6; 7, Book 1, pp. 6, 12, Book 2, p. 24; 19, pp. 5, 7, 8). The samples were analyzed under the EPA CLP for total metals and cyanide analysis by ILM05.3/ILM05.4 (Ref. 6; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, p. 2). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The minimum reporting limits are contained on the analytical data sheets in Reference 6. The minimum reporting limits on the analytical data sheets are the sample specific and analyte specific adjusted CLP CRQLs, which correspond to the lowest quantitative point on the calibration curve (Ref. 11).

TABLE 26: Analytical Results for Background Samples - July 2007

Hazardous Sample ID Concentration MRL References Substance Background for Ore Knob Branch and Peak Creek 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Arsenic 3.3J (5.74) mg/kg 1.9 mg/kg 9, p. 2; 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Cadmium 0.94U mg/kg 0.94U mg/kg 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Chromium 47 mg/kg 1.9 mg/kg 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Copper 500J (610) mg/kg 4.7 mg/kg 9, p. 2; 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Mercury 0.20U mg/kg 0.20 mg/kg 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Nickel 13J (17.55) mg/kg 7.5 mg/kg 9, p. 2; 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Selenium 1.3UJ mg/kg 6.6 mg/kg 19, p. 8 6, p. 84; 7, Book 2, p. 24; OK015-SD-001 Zinc 170J (255) mg/kg 11 mg/kg 9, p. 2; 19, p. 8 Background for Little Peak Creek 6, p. 69; 7, Book 1, p. 24; OK022-SD-001 Copper 5.7J (6.95) mg/kg 2.8 mg/kg 9, p. 4; 19, p. 7 Background for South Fork New River 6, p. 43; 7, Book 1, p. 6; OK-020-SD-001 Copper 9.8J (11.95) mg/kg 2.9 mg/kg 9, p. 3; 19, p. 5

77 SW-Observed Release

Notes:

( ) Concentration was adjusted in accordance with References 8, 9, 10, and 12 ID Identification number J The identification of the analyte is acceptable; the reported value is an estimate mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob Q-2 Result is greater than MDL but less than MRL. The MDL is the lowest concentration of a hazardous substance that a method can detect reliably in either a sample or blank. SD Sediment U Analyte was not detected at or above the reporting limit UJ Analyte was not detected at or above the reporting limit. The value (quantitation) is an estimate, but the presence of the analyte is not in doubt.

78 SW-Observed Release

Contaminated Samples

Sediment samples listed in Table 27 were collected along Ore Knob Branch, Little Peak Creek, Peak Creek, and South Fork New River during the July 2007 ESI conducted by Black & Veatch (Refs. 5, Table 3-2; 7, Book 1, pp. 14, 27, Book 2, pp. 2, 12, 13, 16, 21, 26, 28; 19, pp. 5, 7, 8, 9, 11). The sediment samples were collected in accordance with the SESD operating procedures SESDPROC-200-R0 and the final sampling plan (Refs. 5, pp. 14, 20; 18, pp. 15, 16; 51). Background sediment sample results are presented in Table 26 of this documentation record. Background sediment sample OK015-SD-001 was compared to samples collected along Ore Knob Branch and Peak Creek. Background sediment sample OK022-SD-001 was compared to samples collected along Little Peak Creek. Background sediment sample OK020-SD-001 was compared to samples collected along South Fork New River. The background and release sediment samples were collected at depths ranging from 0 to 3 inches below the stream bed (bsb) (Ref. 7, Book 1, pp. 14, 27, Book 2, pp. 2, 12, 13, 16, 21, 26, 28). The background sediment samples were collected in accordance with the EPA Region 4, SESD operation procedure SESDPROC-200-R0 (Refs. 5, pp. 14, 20; 51). The locations of the sediment samples are provided in Figure 3-1 of Reference 5. The traffic reports are provided in Reference 19 and the sample delivery groups are contained in Reference 8.

TABLE 27: Sediment Samples – July 2007 Estimated Depth Distance Date Sample ID Sample Location (bsb) References from PPE Sampled Ore Knob Branch and Peak Creek 0.03 mile Ore Knob Branch, from PPE 1 0 to 3 3; 5, Table 3-2, OK013-SD-001 downstream of tailings 7/19/2007 Figure 3-1; 7, Book 0.64 mile inches impoundment 1, p. 27; 19, p. 11 from PPE 3 0.03 mile Ore Knob Branch, from PPE 1 0 to 3 3; 5, Table 3-2, OK013-SD-001D downstream of tailings 7/19/2007 Figure 3-1; 7, Book 0.64 mile inches impoundment 1, p. 27; 19, p. 11 from PPE 3 Ore Knob Branch, 0.77 mile 3; 5, Table 3-2, upstream of the from PPE 1 OK014-SD-001 1 inch 7/18/2007 Figure 3-1; 7, Book confluence with Peak 1.37 miles 2, p. 26; 19, p. 9 Creek from PPE 3 Peak Creek, directly 0.79 mile 3; 5, Table 3-2, downstream of the from PPE 1 OK016-SD-002 3 inches 7/18/2007 Figure 3-1; 7, Book confluence with Ore 1.39 miles 2, p. 21; 19, p. 8 Knob Branch from PPE 3 3.06 miles Peak Creek, upstream of from PPE 1 3; 5, Table 3-2, OK017-SD-001 the confluence with Little 3 inches 7/18/2007 Figure 3-1; 7, Book 3.67 miles Peak Creek 2, p. 16; 19, p. 8 from PPE 3 Little Peak Creek

Little Peak Creek, 0 mile, at 3; 5, Table 3-2, 3 inches OK024-SD-001 directly downstream of PPE 2 7/18/2007 Figure 3-1; 7, Book the Former Mill 2, p. 13; 19, p. 7

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TABLE 27: Sediment Samples – July 2007 Estimated Depth Distance Date Sample ID Sample Location (bsb) References from PPE Sampled Little Peak Creek, 3; 5, Table 3-2, upstream of the 0.61 mile 0 to 3 OK023-SD-001 7/18/2007 Figure 3-1; 7, Book confluence with Low Gap from PPE 2 inches 1, p. 14; 19, p. 7 Branch Little Peak Creek, 3; 5, Table 3-2, upstream of the 2.14 mile OK021-SD-001 3 inches 7/18/2007 Figure 3-1; 7, Book confluence with Peak from PPE 2 2, p. 12; 19, p. 7 Creek South Fork New River 3.66 miles South Fork New River, from PPE 1 3; 5, Table 3-2, downstream of the 2.74 miles OK019-SD-002 2 inches 7/17/2007 Figure 3-1; 7, Book confluence with Peak from PPE 2 2, p. 2; 19, p. 5 Creek 4.27 miles from PPE 3 3.92 miles South Fork New River, from PPE 1 3; 5, Table 3-2, downstream of the 2.99 miles OK027-SD-001 2 inches 7/19/2007 Figure 3-1; 7, Book confluence with Peak from PPE 2 2, p. 28; 19, p. 11 Creek 4.53 miles from PPE 3

Notes: bsb Below stream bed ID Identification number OK Ore Knob PPE Probable point of entry SD Sediment

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Contaminated Concentrations

Samples listed in Table 28 were collected from Ore Knob Branch, Peak Creek, Little Peak Creek, and South Fork New River during the 2007 ESI conducted by Black & Veatch (Refs. 5, Table 3-2; 19, pp. 5, 7, 8, 9, 11). The samples were analyzed under the EPA CLP for total metals and cyanide analysis by SOW ILM05.3/ILM05.4 (Refs. 6, p. 2; 13; 14). EPA Region 4, SESD reviewed all data according to the contract SOW and EPA guidelines (Ref. 6, p. 2). SESD used the current Analytical Support Branch, Laboratory Operations and Quality Assurance Manual (that contains internal EPA Region 4 guidelines) for data review, validation, and verification (Ref. 15). The minimum reporting limits are contained on the analytical data sheets in Reference 6. The minimum reporting limits on the analytical data sheets are the sample specific and analyte specific adjusted CLP CRQLs, which correspond to the lowest quantitative point on the calibration curve (Ref. 11).

TABLE 28: Analytical Results for Sediment Samples – July 2007

Hazardous Sample ID Concentration MRL References Substance Ore Knob Branch and Peak Creek 6, p. 107; 7, Book 1, p. OK013-SD-001 Cadmium 1.7 mg/kg 0.83 mg/kg 27; 19, p. 11 6, p. 107; 7, Book 1, p. OK013-SD-001 Mercury 0.40 mg/kg 0.18 mg/kg 27; 19, p. 11 6, p. 107; 7, Book 1, p. OK013-SD-001 Selenium 21J (8.82) mg/kg 5.8 mg/kg 27; 9, p. 9; 19, p. 11 6, p. 108; 7, Book 1, p. OK013-SD-001D Cadmium 2.2 mg/kg 0.86 mg/kg 27; 19, p. 11 6, p. 108; 7, Book 1, p. OK013-SD-001D Mercury 0.58 mg/kg 0.14 mg/kg 27; 19, p. 11 6, p. 108; 7, Book 1, p. OK013-SD-001D Selenium 17J (7.14) mg/kg 6.0 mg/kg 27; 9, p. 9; 19, p. 11 6, p. 89; 7, Book 2, p. 26; OK014-SD-001 Cadmium 1.9 mg/kg 1.2 mg/kg 19, p. 9 6, p. 89; 7, Book 2, p. 26; OK014-SD-001 Mercury 0.30 mg/kg 0.20 mg/kg 19, p. 9 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Arsenic 67J (38.51) mg/kg 5.1 mg/kg 9, p. 6; 19, p. 8 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Chromium 390 mg/kg 5.1 mg/kg 19, p. 8 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Copper 99,000J (99,000) mg/kg 64 mg/kg 9, p. 6; 19, p. 8 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Nickel 350J (350) mg/kg 20 mg/kg 9, p. 6; 19, p. 8 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Selenium 260 mg/kg 18 mg/kg 19, p. 8

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TABLE 28: Analytical Results for Sediment Samples – July 2007

Hazardous Sample ID Concentration MRL References Substance 6, p. 86; 7, Book 2, p. 21; OK016-SD-002 Zinc 3,200J (3,200) mg/kg 31 mg/kg 9, p. 7; 19, p. 8 6, p. 88; 7, Book 2, p. 16; OK017-SD-001 Mercury 1.2 mg/kg 0.15 mg/kg 19, p. 8 Little Peak Creek 6, p. 67; 7, Book 2, p. 13; OK024-SD-001 Copper 400J (400) mg/kg 3.9 mg/kg 9, p. 7; 19, p. 7 6, p. 70; 7, Book 1, p. 14; OK023-SD-001 Copper 100J (100) mg/kg 3.0 mg/kg 9, p. 7; 19, p. 7 6, p. 66; 7, Book 2, p. 12; OK021-SD-001 Copper 340J (340) mg/kg 3.6 mg/kg 9, p. 8; 19, p. 7 South Fork New River 6, p. 109; 7, Book 2, p. OK027-SD-001 Copper 570J (467.21) mg/kg 2.9 mg/kg 28; 9, p. 5; 19, p. 11

Notes: ( ) Concentration was adjusted in accordance with References 8, 9, 10, and 12 D Duplicate sample J The identification of the analyte is acceptable; the reported value is an estimate mg/kg Milligrams per kilogram MRL Minimum reporting limit OK Ore Knob SD Sediment

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Attribution

Mining activities at Ore Knob occurred in two areas that include a 19th Century Operations Area and the Former 1950s Mine and Mill area (Ref. 5, Figures 2-2 and 2-3). Mining activities began as early as the 1850s and continued intermittently until about 1962 (Refs. 33, pp. 1, 4, 7; 40, p. 44). During the 1870s and 1880s Ore Knob was one of the largest copper producers in the eastern states, producing about 25 million pounds of copper between 1873 and 1883 (Refs. 31, p. 3; 33, p. 1; 40, p. 44). Mining and mineral-related activities at the property included mining, concentration, roasting, smelting, and waste management (Ref. 31, p. 3). During operations, mining activities were conducted from 11 shafts (Refs. 30, p. 5; 32, p. 19; 40, p. 44). Based on Bureau of Mines diagrams, the shafts are located from west to east in the areas currently referred to as the Former 1950s Mine and Mill area and the 19th Century Operations Area (Refs. 5, Figure 2-2; 25; 31, Figure 2). The 19th century operation most likely generated various types of slag and roasting wastes as well as waste rock and poor ore (Ref. 34, p. 27). These waste materials most likely were disposed of in areas near the mine shafts (Ref. 34, p. 27). A partially barren area shown on Figure 2-2 of Reference 5 contains waste materials up to several feet deep, with at least some of the material appearing to have been smelted or roasted (Ref. 5, p. 12, Figure 2-2, Appendix E, p. E-30, E-31, E-32, E-36). Some of the tailings generated during the 1957 to 1962 operations at the Former Mine and Mill area were deposited in a 2-acre tailings area located in the northern portion of the property. However, most of the tailings generated during operation of the Former 1950s Mine and Mill were piped to the 20-acre tailings impoundment (currently a waste pile, Source No. 1) located northeast of the mill (Refs. 5, p. 3; 42, p. 6; 45, pp. 1, 2, 3). The location of the tailings pipeline, described by a former Ore Knob Mine employee, is depicted on References 25 and 45, p. 3. Mining activities at Ore Knob ceased around 1962 (Ref. 33, p. 7). Anoxic limestone drains were constructed at the mouths of the adits to intercept groundwater seeps (Ref. 42, p. 13). While these ALDs have improved the pH of discharge from the former mine to about 5 standard units, acid mine drainage from the adits and seeps from the tailings pile continues to impact downstream surface water bodies including Ore Knob Branch, Little Peak Creek, and Peak Creek (Refs. 5, pp. 62 through 65, Figure 5-16; 29, p. 1; 42, p. 15).

As documented in the paragraphs below, metals contained in the sources at the 19th Century Operations Area and the Former 1950s Mine and Mill at Ore Knob have been released to Ore Knob Branch, Peak Creek, Little Peak Creek, and the South Fork New River (Refs. 3; 5, Tables A.1-1 through A-1-4 and A.4-1 through A.4-4). The concentrations of metals detected meet the criteria for documenting an observed release to surface water. The same hazardous substances that are present at elevated concentrations in sources that do not have surface water runoff containment were detected in surface water bodies receiving drainage from the sources at levels significantly greater than upstream background samples. Photographs of the receiving surface water bodies show bright orange stained surface water and sediments, foaming, and visual evidence of the long term releases and extreme impact on surface water bodies receiving drainage from the sources on Ore Knob (Ref. 5, Appendix E, pp. E-116, E-120, E-122, E-123, E-125, E-127, E-129, E-139, E-140, E-142, E-148, and E-165). Impacts of releases from sources at Ore Knob have resulted in Ore Knob Branch, Little Peak Creek, and Peak Creek below Ore Knob Branch being devoid of fish (Ref. 39, p. 7, Appendix B, p. B20). Also, an observed release of copper has been documented in the South Fork New River, a National Wild and Scenic River (Refs. 6, pp. 36, 109; 55, p. 1; 56, pp. 2, 3). The 15-mile TDL for sources in the two areas at Ore Knob overlap at Peak Creek and the South Fork New River (Ref. 3).

Analytical results of waste and soil samples collected from Source Nos. 1 (main tailings pile), 2 (contaminated soil), and 3 (slag dump waste pile) located in the 19 Century Operations Area contained arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel, selenium, silver, and/or zinc (see Tables 2, 8, and 11 of this HRS documentation record). The highest concentrations of copper, mercury, and zinc detected in waste samples from Source No. 1 (main tailings pile) include: 7,300J mg/kg, 0.71 mg/kg, and 1,600J mg/kg, respectively (see Table 2 of this HRS documentation record). Surface water samples collected from ponds located along the margin of Source No. 1 also contained similar hazardous substances (Ref. 5, Appendix A, Table A.3-5). During the 2007 sampling event, seeps were observed

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emanating from the face of the dam of the main tailings pile (Refs. 7, Book 1, pp. 15, 16, 29; 50, p. 6). Surface water samples collected from these seeps contained cadmium, chromium, copper, manganese, mercury, selenium, and zinc (Ref. 5, Appendix A, Table A.3-5).

Runoff from Source No. 1 discharges to PPE 1 into Ore Knob Branch, and runoff from Source Nos. 2 and 3 discharge at PPE 3 into the headwaters of Ore Knob Branch (Refs. 3; 25) (also see Figures 2, 3, and 4 of this HRS documentation record). These three sources release to the same receiving waters within the 15- mile TDL via PPEs 1 and 3 (Refs. 3; 25) (also see Figures 2, 3, and 4 of this HRS documentation record). Sediment samples collected from Ore Knob Branch, Peak Creek, and the South Fork New River downstream of Source Nos. 1, 2, and 3 contained elevated concentrations of cadmium, chromium, copper, mercury, nickel, selenium, silver, and zinc (see Tables 26 and 28 of this HRS documentation record). Documentation of these hazardous substances in Ore Knob Branch, Peak Creek, and the South Fork New River show continued releases from the sources at the 19th Century Operations Area (see sections 2.2 and 4.0 of this HRS documentation record).

Analytical results of waste and soil samples collected from Source Nos. 4 (tailings pile) and 5 (contaminated soil) located in the Former 1950s Mine and Mill area contained arsenic, cadmium, chromium, copper, mercury, nickel, selenium, silver, and zinc (see Tables 14, 15, 18, and 21 of this HRS documentation record). In the Former 1950s Mine and Mill, Source No. 4 contained the highest concentration of zinc, 2,500J mg/kg, and Source No. 5 contained the highest concentration of copper and mercury, 9,600J mg/kg and 0.31 mg/kg, respectively (see Tables 15 and 21 of this HRS documentation record). Soil samples collected from drainage routes (OK423 and OK425) in the Former 1950s Mine and Mill area contained elevated concentrations of hazardous substances including cadmium, copper, mercury, selenium, silver, and zinc (Refs. 5, Table 3-5; 6, pp. 76, 91) (also see Tables 18 and 21 of this HRS documentation record).

Runoff from Sources 4 and 5 discharge at PPE 2 into Little Peak Creek (Refs. 3; 25) (also see Figures 5 and 6 of this HRS documentation record). Therefore, these two sources release to the same receiving waters within the 15-mile TDL via PPE 2 (Refs. 3; 25) (also see Figures 5 and 6 of this HRS documentation record). Sediment samples collected from Little Peak Creek, Peak Creek, and the South Fork New River downstream of Source Nos. 4 and 5 contained elevated concentrations of copper (see Table 28 of this HRS documentation record). Documentation of this hazardous substance in Little Peak Creek, Peak Creek, and the South Fork New River shows continued releases from the sources at the Former 1950s Mine and Mill area (see sections 2.2 and 4.0 of this HRS documentation record).

Releases from the two clusters of sources, Source Nos. 1, 2, and 3 at PPEs 1 and 3, and Source Nos. 4 and 5 at PPE 2 , impact overlapping portions of the TDL at Peak Creek (downstream of Little Peak Creek) and the South Fork New River (Refs. 3; 25). Analytical results for sediment samples collected during the 2007 ESI from various locations throughout the 19th Century Operations Area, the Former 1950s Mine and Mill area, the main tailings pile, and surface water bodies that receive runoff from the Ore Knob property, indicate that the following hazardous substances are present in sources at the property and in downstream receiving waters: arsenic, cadmium, chromium, copper, mercury, nickel, selenium, and zinc (Ref. 6) (also see Sections 2.2.2 and 4.1.2.1.1 of this HRS documentation record). Also, toxic concentrations of copper and zinc, above the North Carolina freshwater action levels, were detected in surface water samples collected by the North Carolina Division of Water Quality before and after the mine reclamation project (Ref. 39, pp, 6, 7; Appendix B, pp. B-10, B-11, B20). During the North Carolina Divisions of Water Quality studies, pH was the most notable parameter affecting the water quality of the receiving waters of Ore Knob (Ref. 39, Appendix B, p. B11).

Ore Knob Branch and Little Peak Creek originate at Ore Knob Mine (Ref. 3). Hazardous substances detected at or immediately downstream of PPEs 1, 2, and 3 were also detected in the downstream samples (Refs. 3; 6; 25) (see Section 4.1.2.1.1 of this HRS documentation record). According to NCDENR personnel, there are no industrial sources or other sources of metals contamination that impact surface

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water bodies within the TDL. Also, Ore Knob Mine is the only copper mine in the area (Ref. 45, p. 2). Peak Creek above Ore Knob Branch receives agricultural runoff; however, a fairly good fish habitat is present in Peak Creek above Ore Knob Branch (Ref. 39, Appendix B, p. B20). Table 29 provides a summary of the sources, hazardous substances associated with each source, the PPE located immediately downstream of each source, and the hazardous substances detected at or downstream of each PPE.

TABLE 29: Hazardous Substances in the Release Hazardous Substances Meeting Source Hazardous Substances Observed Release Criteria at and No. Associated with the Source PPE Downstream of the PPE 1 Cadmium, chromium, copper, mercury, 1 Arsenic, cadmium, chromium, copper, zinc mercury, nickel, selenium, and zinc 2 Cadmium, chromium, copper, mercury, 3 Arsenic, cadmium, chromium, copper, nickel, silver mercury, nickel, selenium, and zinc 3 Copper, manganese, silver, zinc 3 Arsenic, cadmium, chromium, copper, mercury, nickel, selenium, and zinc 41 Cadmium, copper, mercury, selenium, 2 Copper silver, zinc 51 Arsenic, cadmium, chromium, copper, 2 Copper mercury, nickel, selenium, silver, zinc

Notes:

1 Sources where a sample was collected at the PPE No. Number PPE Probable point of entry

Hazardous Substances in the Release

Arsenic Cadmium Chromium Copper Mercury Nickel Selenium Zinc

Surface Water Observed Release Factor Value: 550.00

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4.1.2.2 Drinking Water Threat Waste Characteristics

4.1.2.2.1 Toxicity/Persistence

The toxicity and persistence factor values for the hazardous substances detected in the source samples with containment factor values of greater than 0 are summarized in Table 30. The hazardous substances listed below, with the exception of manganese and silver, were detected in sediment samples collected from the South Fork New River or one of its tributaries within the TDL. The combined toxicity and persistence factor values are assigned in accordance with Reference 1, Section 4.1.2.2.1. Also see Section 2.2.2 for Sources 1 through 5 and Section 4.1.2.1.1, Observed Release by Chemical Analysis, of this HRS documentation record.

TABLE 30: Surface Water Toxicity/Persistence

Does Hazardous Substance Meet Toxicity/

Toxicity Persistence Observed Persistence Factor Hazardous Factor Factor Release? Value Substance Source No. Value Value1 (Yes/No) (Ref. 1, Table 4-12) Reference Arsenic 5 10,000 1 Yes 10,000 2, p. BI-1 Cadmium 1, 2, 4, 5 10,000 1 Yes 10,000 2, p. BI-2 Chromium 1, 2, 5 10,000 1 Yes 10,000 2, p. BI-3 Copper 1, 2, 3, 4, 5 0 1 Yes 0 2, p. BI-3 Manganese 3 10,000 1 No 10,000 2, p. BI-8 Mercury 1, 2, 4, 5 10,000 1 Yes 10,000 2, p. BI-8 Nickel 2, 5 10,000 1 Yes 10,000 2, p. BI-9 Selenium 5 100 1 Yes 100 2, p. BI-10 Silver 2, 3, 4, 5 100 1 No 100 2, p. BI-10 Zinc 1, 3, 4, 5 10 1 Yes 10 2, p. BI-12

Notes:

1 Persistence factor value for rivers Ref. Reference

Toxicity/Persistence Factor Value: 10,000.00 (Reference 1, Section 4.1.2.2.1, Table 4-12)

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4.1.2.2.2 Hazardous Waste Quantity

TABLE 31: Hazardous Waste Quantity Source No. Source Type Source Hazardous Waste Quantity 1 Pile 67,024.23 2 Contaminated soil >0 3 Pile >0 4 Pile 5,699.384 5 Contaminated soil >0

The hazardous constituent quantity for Source No. 1 is not adequately determined. The estimated area of the main tailings pile is 871,315 ft2 (Refs. 5, Figure 3-4; 25; 61).

The hazardous constituent quantity for Source No. 2 is not adequately determined. The area of contaminated soil located in the 19th Century Operations Area is undetermined but >0 (Refs. 5, Figure 3- 2; 25).

The hazardous constituent quantity for Source No. 3 is not adequately determined. The area of the multiple piles located throughout the 19th Century Operations Area is undetermined but >0 (Refs. 5, Figure 3-2; 25).

The hazardous constituent quantity for Source No. 4 is not adequately determined. The area of the tailings pile located at the former 1950s mill is estimated to be 74,092 ft2 (Refs. 5, Figure 3-3; 25; 61).

The hazardous constituent quantity for Source No. 5 is not adequately determined. The area of the contaminated soil located throughout the former 1950s mill area is undetermined but >0 (Refs. 5, Figure 3-3; 25).

Hazardous Waste Quantity Factor Value: 10,000 (Reference 1, Table 2-6)

4.1.2.2.3 Calculation Of Drinking Water Threat Waste Characteristics Factor Category Value

The waste characteristics factor category was obtained by multiplying the toxicity/persistence and HWQ factor values, subject to a maximum product of 1 x 108. Based on this product, a value was assigned in accordance with Reference 1, Table 2-7.

Toxicity/Persistence Factor Value: 10,000.00 Hazardous Waste Quantity Factor Value: 10,000

Toxicity/Persistence Factor Value × Hazardous Waste Quantity Factor Value: 1 x 108

Waste Characteristics Factor Category Value: 100 (Reference 1, Table 2-7)

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4.1.2.3 Drinking Water Threat Targets

No surface water intakes are located within the 15-mile TDL downstream of the Ore Knob property (Refs. 20; 21; 23, pp. 2, 8, 20, 32, 45).

4.1.2.3.3 Resources

TABLE 32: Resources Surface Water Body Resource Use Reference Peak Creek Major/Designated Recreation Area 24, pp. 1, 2, 9; 55, p. 1; 56, pp. 2, 3, 8, 10 South Fork New River Major/Designated Recreation Area 24, pp. 1, 2, 9; 55 p. 1; 56, pp. 2, 3, 8, 10

Peak Creek and South Fork New River are used for recreational activities including fishing and swimming (Ref. 24, pp. 1, 2, 9). Also the New River State Park, a portion of which is located on the South Fork New River, is used for camping, canoeing, picnicking, and fishing (Refs. 55, p. 1; 56, pp. 2, 3, 8, 10).

Resources Factor Value: 5.00 (Ref. 1, Section 4.1.2.3.3)

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4.1.3.2 Human Food Chain Threat Waste Characteristics

4.1.3.2.1 Toxicity/Persistence/Bioaccumulation

The toxicity, persistence, and bioaccumulation factor values for the hazardous substances detected in the source samples with containment factor values of greater than 0 are summarized in Table 33. The hazardous substances listed below, with the exception of manganese and silver, were detected in sediment samples collected from the South Fork New River or one of its tributaries within the TDL. The combined toxicity, persistence, and bioaccumulation factor values are assigned in accordance with Reference 1, Section 4.1.3.2.1. Also see Section 2.2.2 for Sources 1 through 5 and Section 4.1.2.1.1, Observed Release by Chemical Analysis, of this HRS documentation record.

TABLE 33: Toxicity/Persistence/Bioaccumulation

Toxicity/ Persistence/ Toxicity Persistence Bioaccu- Bioaccumulation Hazardous Source Factor Factor mulation Factor Value Substance No. Value Value1 Value2 (Ref. 1, Table 4-16) Reference Arsenic 5 10,000 1 5 5E+4 2, p. BI-1 Cadmium 1, 2, 4, 5 10,000 1 5,000 5E+7 2, p. BI-2 Chromium 1, 2, 5 10,000 1 500 5E+6 2, p. BI-3 Copper 1, 2, 3, 4, 5 0 1 500 0 2, p. BI-3 Manganese 3 10,000 1 50,000 5E+8 2, p. BI-8 Mercury 1, 2, 4, 5 10,000 1 50,000 5E+8 2, p. BI-8 Nickel 2, 5 10,000 1 0.5 5E+3 2, p. BI-9 Selenium 5 100 1 50 5E+3 2, p. BI-10 Silver 2, 3, 4, 5 100 1 50 5E+3 2, p. BI-10 Zinc 1, 3, 4, 5 10 1 5 5E+1 2, p. BI-12

Notes:

1 Persistence factor value for rivers 2 Bioaccumulation factor value for freshwater Ref. Reference

Toxicity/Persistence/Bioaccumulation Factor Value: 500,000,000.00 (Ref. 1, Section 4.1.3.2.1.4, Table 4-16)

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4.1.3.2.2 Hazardous Waste Quantity

TABLE 34: Hazardous Waste Quantity Source No. Source Type Source Hazardous Waste Quantity 1 Pile 67,024.23 2 Contaminated soil >0 3 Pile >0 4 Pile 5,699.384 5 Contaminated soil >0

The hazardous constituent quantity for Source No. 1 is not adequately determined. The estimated area of the main tailings pile is 871,315 ft2 (Refs. 5, Figure 3-4; 25; 61).

Hazardous Waste Quantity Factor Value: 10,000 (Reference 1, Table 2-6)

4.1.3.2.3 Calculation Of Human Food Chain Threat Waste Characteristics Factor Category Value

The waste characteristics factor category value was obtained by multiplying the toxicity/persistence and HWQ factor values, subject to a maximum product of 1 x 108. Based on this product, a value was assigned in accordance with Reference 1, Table 2-7.

Toxicity/Persistence Factor Value: 10,000.00 Hazardous Waste Quantity Factor Value: 10,000

Toxicity/Persistence Factor Value × Hazardous Waste Quantity Factor Value: 1 x 108

Toxicity/Persistence Factor Value × Hazardous Waste Quantity Factor Value (1 x 108) × Bioaccumulation Factor Value (50,000): 5 x 1012

Waste Characteristics Factor Category Value: 1,000 (Reference 1, Table 2-7)

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4.1.3.3 Human Food Chain Threat Targets

4.1.3.3.1 Food Chain Individual

As noted in Reference 1, Section 4.1.2.1.1 an observed release of a hazardous substance having a bioaccumulation factor value of 500 or greater is documented in the perennial surface waters of Peak Creek, Little Peak Creek, and South Fork New River (see Tables 26 and 28 of this HRS documentation record). Fishing for human consumption occurs along Peak Creek and South Fork New River within the TDL (Ref. 24, pp. 1, 2, 9; 55, p. 1; 56, p. 10). South Fork New River is stocked with muskellunge south of the Route 221 bridge; this bridge is within the TDL (more than 4 miles upstream of the TDL) (Refs. 3; 56, p. 10).

Food Chain Individual Factor Value: 20 (Ref. 1, Section 4.1.3.3.1)

4.1.3.3.2 Population

4.1.3.3.2.1 Level I Concentrations

No Level I samples were collected.

4.1.3.3.2.2 Level II Concentrations

Level II was not scored.

4.1.3.3.2.3 Potential Human Food Chain Contamination

Fishing occurs along Peak Creek and South Fork New River, downstream of the confluence with Peak Creek (Ref. 24, pp. 1, 2, 9). According to a fishery biologist with the North Carolina Wildlife Resources Commission, recreational fishing is done on Peak Creek and South Fork New River (Ref. 24, pp. 1, 2, 9). The amount of fish caught on an annual basis is not known.

The flow rate for Peak Creek downstream of Ore Knob Branch is about 7.8 cfs (Ref. 5, Table 3-4). The average flow rate for South Fork New River near Jefferson, North Carolina from water years 1925 to 2007 is 427.3 cfs (Ref. 26, pp. 1 through 3). Information is not available on the annual production of fish caught in Peak Creek and South Fork New River. Therefore, because Peak Creek and South Fork New River are fisheries, the annual production for each water body, although not scored, is undetermined but greater than zero (Ref. 24, pp. 1, 2, 9).

Potential Human Food Chain Factor Value: Not Scored (Reference 1, Section 4.1.3.3.2.3)

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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, and bioaccumulation factor values for the hazardous substances detected in the source samples with containment factor values of greater than 0 are summarized in Table 35. The hazardous substances listed below, with the exception of manganese and silver, were detected in sediment samples collected from the South Fork New River or one of its tributaries within the TDL. The combined ecosystem toxicity, persistence, and bioaccumulation factor values are assigned in accordance with Reference 1, Section 4.1.4.2.1. Also see Section 2.2.2 for Sources 1 through 5 and Section 4.1.2.1.1, Observed Release by Chemical Analysis, of this HRS documentation record.

TABLE 35: Ecosystem Toxicity/Persistence/Bioaccumulation Ecosystem/ Ecosystem Toxicity/ Toxicity Persistence Bioaccu- Bioaccumulation Hazardous Source Factor Factor mulation Factor Value Substances No. Value1 Value2 Value3 (Ref. 1, Table 4-21 Reference Arsenic 5 10 1 5,000 5E+4 2, p. BI-1 Cadmium 1, 2, 4, 5 10,000 1 50,000 5E+8 2, p. BI-2 Chromium 1, 2, 5 10,000 1 500 5E+6 2, p. BI-3 Copper 1, 2, 3, 4, 5 1,000 1 5,000 5E+6 2, p. BI-3 Manganese 3 0 1 50,000 0 2, p. BI-8 Mercury 1, 2, 4, 5 10,000 1 50,000 5E+8 2, p. BI-8 Nickel 2, 5 100 1 500 5E+4 2, p. BI-9 Selenium 5 1,000 1 500 5E+5 2, p. BI-10 Silver 2, 3, 4, 5 10,000 1 50 5E+5 2, p. BI-10 Zinc 1, 3, 4, 5 10 1 50,000 5E+5 2, p. BI-12

Notes: 1 Ecotoxicity for freshwater 2 Persistence value for rivers 3 Bioaccumulation factor value for freshwater Ref. Reference

Ecosystem Toxicity/Persistence/Bioaccumulation Factor Value: 500,000,000 (Reference 1, Section 4.1.4.2.1, Table 4-21)

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4.1.4.2.2 Hazardous Waste Quantity

TABLE 36: Hazardous Waste Quantity Source No. Source Type Source Hazardous Waste Quantity 1 Pile 67,024.23 2 Contaminated soil >0 3 Pile >0 4 Pile 5,699.384 5 Contaminated soil >0

The hazardous constituent quantity for Source No. 1 is not adequately determined. The estimated area of the main tailings pile is 871,315 ft2 (Refs. 5, Figure 3-4; 25; 61).

Hazardous Waste Quantity Factor Value: 10,000 (Reference 1, Table 2-6)

4.1.4.2.3 Calculation Of Environmental Threat Waste Characteristics Factor Category Value

The waste characteristics factor category was obtained by multiplying the ecosystem toxicity/persistence and HWQ factor values, subject to a maximum product of 1 x 108. Then this product was multiplied by the bioaccumulation potential factor value, subject to a maximum product of 1 x 1012. Based on this product, a value was assigned in accordance with Reference 1, Table 2-7.

Ecosystem Toxicity/Persistence Factor Value: 10,000.00 Hazardous Waste Quantity Factor Value: 10,000

Ecosystem Toxicity/Persistence Factor Value × Hazardous Waste Quantity Factor Value: 1 x 108

Ecosystem Toxicity/Persistence Factor Value × Hazardous Waste Quantity Factor Value (1 x 108) × Bioaccumulation Factor Value (50,000): 5 x 1012

Waste Characteristics Factor Category Value: 1,000 (Reference 1, Table 2-7)

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4.1.4.3 Environmental Threat Targets

Level I Concentrations

No Level I concentrations have been documented.

Level II Concentrations

The South Fork New River, including the portion within the TDL, is a federally designated Wild and Scenic River (Refs. 55, p. 1; 56, p. 2).

Most Distant Level II Sample

Sample ID: OK027 Distance from the probable point of entry: 3.92 miles from PPE 1, 2.99 miles from PPE 2, and 4.53 miles from PPE 3 Reference: 3; 5, Figure 3-1; 7, Book 2, p. 28

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4.1.4.3.1 Sensitive Environments

4.1.4.3.1.1 Level I Concentrations

Sensitive Environments

Level I sensitive environments were not evaluated within the 15-mile downstream TDL (Refs. 3; 55, p. 1; 56, pp. 2, 3).

Wetlands

No wetlands have been identified within the 15-mile downstream target distance limit (Refs. 3; 44).

Level I Concentrations Value: Not Scored

4.1.4.3.1.2 Level II Concentrations

Sensitive Environments

The South Fork New River is a federally designated Wild and Scenic River (Refs. 55, p. 1; 56, pp. 2, 3, 4). The designated scenic segment of the river is 26.5 miles in length and includes 22 miles of the South Fork downstream to its confluence with the North Fork and 4.5 miles of the main stem of the river north to the Virginia line (Refs. 55, p. 1; 56, p. 4). About 12.5 miles of the designated Wild and Scenic River are located within the TDL, which includes the portion of the TDL from the confluence of Peak Creek and the South Fork New River to the TDL 3 located near Ashe County Road 1560 (Refs. 3; 56, p. 3). The North Carolina Division of Water Quality has designated the South Fork New River as an Outstanding Water Resource, which provided water quality protection (Ref. 37, pp. 44, 45).

Level II Sensitive Environment Targets

TABLE 37: Level II Sensitive Environment Targets

Sensitive Distance from PPE to Environment Nearest Sensitive Value (Ref. 1, Table Sensitive Environment Environment 4-23) References 3.92 miles from PPE 1, 1, Table 4-23; 3; South Fork New River 50 2.99 miles from PPE 2, 55, p. 1; 56, pp. 2, (federally designated Wild and 4.53 miles from PPE 3 and Scenic River) 3

Wetlands

No wetlands have been identified within the 15-mile downstream target distance limit (Refs. 3; 44).

Level II Concentrations Value: 50.0 Reference 1, Table 4-23

95 SW-Environmental Threat

4.1.4.3.1.3 Potential Contamination

Sensitive Environments:

Potential sensitive environments were not evaluated because Level II sensitive environments were evaluated (Refs. 3; 55, p. 1; 56, pp. 2, 3).

Wetlands:

No wetlands have been identified within the 15-mile downstream target distance limit (Refs. 3; 44).

Potential Contamination Factor Value: Not Scored

96 SW-Environmental Threat