### HRS DOCUMENTATION RECORD COVER SHEET

Name of Site: Washington County Lead District– Furnace Creek

EPA ID No. : MON000705842

Contact Persons

EPA Contact: Michelle Quick U.S. Environmental Protection Agency, Region 7 901 North 5th Street Kansas City, Kansas 66101 (913) 551-7335

Documentation Record: Kumud Pyakuryal, Tetra Tech EM Inc.

Pathways, Components, or Threats Not Scored

Although evidence of soil and ground water contamination exists, the Ground Water Migration, Soil Exposure, and Air Migration Pathways are not scored because the listing decision is not significantly affected by those pathways (Ref. 7, pp. 8-10, 20, 1079-1534). The air migration pathway was not scored, because its score will not affect the NPL listing decision.

### HRS DOCUMENTATION RECORD

Name of Site: Washington County Lead District – Furnace Creek

EPA Region: 7

Date Prepared: October 2010

Street Address of Site*: Approximately 2.0 mile s north of the intersection of the Big River and Highway 21 (see Figure 1 in Reference 12 and Figure 2 Reference 13) City, County, State, Zip Code: Caledonia, Washington County, Missouri 63631

General Location in the State: The site is located in the Southwest 1⁄4 of Jefferson County, Missouri (Ref. 3, p. 1; 12, p. 1).

Topographic Map: The location of site is shown on the, U.S. Geological Survey, 7.5-Minute Series Topographic Map for Belgrade, Missouri Quadrangle and Irondale, Missouri Quadrangle (Ref.3).

Latitude and Longitude*: 37° 50’ 25.91’’ North and 90° 47’ 58.40’’ West

The latitude and longitude coordinat es listed above specify the approximate center of Source 1(Furnace Creek Tailings Pile) presented in Figure 1 in Referen ce 12 and topographic maps included in Reference 3.

Scores Air Pathway Not Scored Ground Water Pathway Not Scored Soil Exposure Pathway Not Scored Surface Water Pathway 100.00 HRS SITE SCORE 50.00

* - The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area in which the site is located. They represent one or more locations EPA considers to be part of the site based on the screeni ng information EPA used to evaluate the site for NPL listing. EPA lists national priorities among the know n "releases or threatened releases" of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has been "deposited, st ored, placed, or otherwise come to be located." Generally, HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to be addressed under the Comprehensive Environmental Response, Compensation, and Liability Act. Accordingly, EP A contemplates that the preliminary description of facility boundaries at the time of scoring will be refine d as more information is developed as to where the contamination has come to be located.

1

### WORKSHEET FOR COMPUTING HRS SITE SCORE

S S 2


### 1. Ground Water Migration Pathway Score (S gw 

### ) (from Table 3-1, line 13) NS NS

2a. Surface Water Overland/Flood Migration Component (from Table 4-1, line 30) 100.00

2b. Ground Water to Surface Water Migration Component (from Table 4-25, line 28) 0.00

2c. Surface Water Migration Pathway Score (S sw 

### ) Enter the larger of lines 2a and 2b as the pathway score. 100.00 10,000

3. Soil Exposure Pathway Score (S s 

### ) (from Table 5-1, line 22) NS NS

4. Air Migration Pathway Score (S a 

### ) (from Table 6-1, line 12) NS NS

5. Total of S gw 2 

### + S sw 2 

### + S s 2 

### + S a 2 

### 10,000 6. HRS Site Score Divide the value on line 5 by 4 and take the square root 50.00

Note:

NS Not Scored

2

### TABLE 4

− 1

SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SPREADSHEET

Factor Categories and Factors Maximum Value Value Assigned Drinking Water Threat Likelihood of Release:

1. Observed Release ...........................................................................................................

.. 2. Potential to Release by Overland Flow: 2a. Containment ............................................................................................................ 2b. Runoff ....................................................................................................................

. 2c. Distance to Surface Water ....................................................................................... 2d. Potential to Release by Over land Flow (lines 2a[2b+2c])....................................... 3. Potential to Release by Flood: 3a. Containmen t (Flood) ............................................................................................... 3b. Flood Frequency...................................................................................................... 3c. Potential to Release (lines 3a × 3b) ........................................................................... 4. Potential to Release (lines 2d+ 3c, subject to a maximum of 500).................................... 5. Likelihood of Release (h igher of lines 1 and 4)................................................................ 550

10 25 25 500

10 50 500 500 550 550

—

—

—

—

—

—

—

— 550
Waste Characteristics:

6. Toxicity /Persist ence ......................................................................................................... 7. Hazardous Waste Quantity............................................................................................... 8. Waste Ch aracteris tics ......................................................................................................

. (a) (a) 100 —

—

— Targets:

9. Nearest Intake..............................................................................................................

... 10. Population 10a. Level I Concentrations........................................................................................... 10b. Level II Concentrations......................................................................................... 10c. Potential C ontamination ........................................................................................ 10d. Population (lines 10a+10b+10c) ........................................................................... 11. Resources .................................................................................................................

...... 12. Targets (lin es 9+10d+11) ............................................................................................... 50

(b) (b) (b) (b) 5 (b) —

—

—

—

—

—

— Drinking Water Threat Score:

13. Drinking Water Threat Score ([lines 5x8x12]/82,500, subject to a minimum of 100)... 100 NS Human Food Chain Threat Likelihood of Release:

14. Likelihood of Release (same value as line 5) ................................................................. 550 550 Waste Characteristics:

15. Toxicity/Persist ency/Bioaccumu lation........................................................................... 16. Hazardous Waste Qu antity ............................................................................................. 17. Waste Ch aracteris tics ..................................................................................................... (a) (a) 1,000 5 × 10 6
1 × 10 4
320 Targets:

18. Food Chain Individual.................................................................................................... 19. Population 19a. Level I Concentrations........................................................................................... 19b. Level II Concentrations......................................................................................... 19c. Potential Human Food Chain Contamination........................................................ 19d. Population (lines 19a+19b+19c) ........................................................................... 20. Targets (l ines 18+19d).................................................................................................... 50

(b) (b) (b) (b) (b) 45

0 0.03

0 0.03 45.03 Human Food Chain Threat Score:

21. Human Food Chain Threat Score ([lines 14 × 17 × 20]/82,500, subject to a maximum of 100)........................................................................................ 100 96.06



### 3

### TABLE 4

− 1 (Continued)

SURFACE WATER OVERLAND/FLOOD MIGRATION COMPONENT SPREADSHEET

4 Factor Categories and Factors Maximum Value Value Assigned Environmental Threat Likelihood of Release:

22. Likelihood of Release (same value as line 5) ................................................................. 550 550 Waste Characteristics:

23. Ecosystem Toxicity/Per sistence/Bioaccu mulation......................................................... 24. Hazardous Waste Qu antity ............................................................................................. 25. Waste Ch aracteris tics ..................................................................................................... (a) (a) 1,000 

### 5 × 10 7 10,000

560 Targets:

26. Sensitive Environments 26a. Level I Concentrations........................................................................................... 26b. Level II Concentrations......................................................................................... 26c. Potential C ontamination ........................................................................................ 26d. Sensitive Environments (lines 26a+26b+26c)....................................................... 27. Targets (value from line 26d) ......................................................................................... (b) (b) (b) (b) (b) NS 25 NS 25 25 Environmental Threat Score:

28. Environmental Threat Score ([lines 22 × 25 × 27]/82,500, subject to a maximum of 60)............................................................................................................. 60 60 Surface Water Overland/Flood Migratio n Component Score for a Watershed 29. Watershed Score (lines 13+21+28, subj ect to a maximum of 100)................................ 100 100.00 Surface Water Overland/Flood Migration Component Score 30. Component Score (S of ) c (highest score from line 29 for all watersheds evaluated, subject to a maximum of 100)........................................................................................ 100 100.00

Notes:

a Maximum value applies to waste characteristics category b Maximum value not applicable c Do not round to highest integer NS Not scored

### REFERENCES

Reference Number Description of the Reference

1 U. S. Environmental Protection Agency (EPA). 1990. Hazard Ranking System, Final Rule, 40 CFR Part 300, Volume 55, No. 241. December 14. Excerpt. 2 Pages. Note: A complete copy of the rule is available at http://www.epa.gov/superfund /sites/nplhrsres/index.htm or from the Region 7 Docket upon request.

2 EPA. 2004. Superfund Chemical Data Matrix. January. Excerpt. 13 Pages. A complete copy of SCDM is available at http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm

. 3 U. S. Geological Survey (USGS). 7.5 minute series Topographic Quadrangle Maps of Missouri: 1981, Belgrade (1958), Scale 1:24,000. 1 Sheet.

4 U.S. Environmental Protection Agency (EPA). 2010. Surf Your Watershed. Updated April 20. Accessed on line at http://cfpub.epa.gov/surf/ on April 20, 2010. 2 pages.

5 Tetra Tech. 2010. Field description and documentation of sources evaluated in support of the Site Inspection Report, under the EPA START 3 Contract (EP-S7-06-01). March 15. 3 pages.

6 Missouri Department of Natural Resources (MDNR). 2009. Seeger, Cheryl, MDNR, to Kumud Pyakuryal, Tetra Tech EM Inc. Memorandum: Southeastern Washington County Area Mining History and Geology. November 25. 14 pages.

7 Tetra Tech. 2009. Removal Site Evaluation Report for WCLD – FC Site. CERCLIS I.D. MON000705842. Under the Superfund Technical Assessment and Response (START) 3 Contract (EP-S7-06-01). March 9. 1,561 pages.

8 Tetra Tech. 2010. Record of Conversation between Dave Gray, Tetra Tech, and George Smith, a resident of Mineral Point, Missouri. Subject: Fishing Activities at th e Furnace Creek Tailings Pond. February 2, 2010. 1 page.

9 Environmental Toxicology and Chemistry. 2005. Toxicity of Sixty-Three Metals and Metalloids to Hyalella Azteca at Two Levels of Water Hardness. 7 pages.

10 Tetra Tech. 2010. Record of telephone Conver sation between Kumud Pyakuryal, Tetra Tech, and Six nearby Property Owners regarding Furnace Creek Tailings Pond (Source 1). February 9. 2
pages.

11 Tetra Tech. 2009. Quality Assurance Project Plan for Site Inspection Activities at Washington County Lead District – Furnace Cr eek (WCLD – FC) in Washington County, Missouri. Under the START 3 Contract (EP-S7-06-01). December 14. 19 pages.

12 Tetra Tech. 2010. Figure 1: Sampling Points and Surface Water Pathway Segments. Under the START 3 Contract (EP-S7-06-01). April 21. 1 page.

13 Tetra Tech. 2010. Figure 2: 15-Mile Target Di stance Limit (TDL). Under the START 3 Contract (EP-S7-06-01). April 21. 1 page.

14 EPA Region 7. 2010. Transmittal of Sample Analysis for ASR #4757 for the WCLD – FC SI sampling. March 2. 34 pages.

15 EPA Region 7. 2010. HRS Analysis Results Supplement for ASR #4757 for the WCLD – FC SI sampling. March 22. 17 pages.

16 EPA Region 7. 2010. Transmittal of Sample Analysis for ASR #4876 for the WCLD – FC SI sampling. April 15. 7 pages.

17 Tetra Tech. 2010. Photo Documentation Record of Field Sampling Activities in support of the Site Inspection. Under the START 3 Contract (EP-S7-06-01). January. 36 pages.

18 Wharton, H.M. Barite Ore Pote ntial of Four Tailings Ponds in the Washington County Barite District, Missouri. Missouri Geological Survey and Water Resources. 1972. Excerpt. 20 pages. 19 Tetra Tech. 2010. Field sheets for ASR #4757 for WCLD – FC Site. January. 102 pages. 20 EPA Region 7. 2010. Chain of Custody for ASR #4757 for WCLD - FC Site. January. 5 pages. 21 EPA Region 7. 2010. Chain of Custody for ASR #4876 for WCLD - FC Site. April. 1 page. 22 Tetra Tech. 2010. Field sheets for ASR #4876 for WCLD – FC Site. April. 5 pages.

23 U.S. Fish and Wildlife Service (USFWS). 2010. National Wetlands Inventory Data for Source 1, at: http://www.fws.gov/wetlands/data/Mapper.h tml. Accessed in April. 4 pages.

24 United States Department of Agriculture. 2003. Soil Survey of Washington County, Missouri. November. Excerpt. 4 pages.



### 5

### 6 Reference Number Description of the Reference

25 MDNR. 2010. Geographic Information System Metadata on Inventory of Mines, Occurrences, and Prospects (IMOP) in Missouri, accessed at: http://www.dnr.mo.gov/gis/NRDSDEP3.GEOLOGY.IMOP.XML#_spdoinfo . July 26. 5 pages.

26 Northern Dynasty Mine. 2010. Pebble Project: Backgrounder, Tailings, and Tailings Management, accessed at: http://www.northerndynastyminerals.com/i/pdf/NDM_Backgrounder_Sep05.pdf

. Accessed on July 27. 4 pages.

27 MDNR. 2001-2002. Biological Assessment and Fine Sediment Study, Upper Big River, Washington County. 60 pages.

28 Tetra Tech. 2010. Washington County Lead – Furnace Creek Sample Correlation and Cross Reference Table. July. 1 page.

29 EPA Region 7. 2010. Memo from Larry Marchin, Project Officer of Contract Laboratory Program (CLP) to Michelle Quick, EPA Region 7 NPL Coordinator regarding ASR # 4757 and # 4876 Analysis Protocols. June. 3 pages.

30 EPA Region 7. 2010. HRS Analysis Results Supplement for ASR #4876 for the WCLD – FC SI sampling. August 9. 1 page.

### SITE DESCRIPTION

The Washington County Lead District - Furnace Creek site investigated by the U.S. Environmental Protection Agency to date is located in the s outheastern portion of Washington County, Missouri. Previous US Environmental Protection Agency (EPA) removal assessment and evaluation reports divided the area into Study Areas 22 through 26 (Ref. 7, p. 17). The five study areas were centered on historical mining operations identified during a review of (1) the Inventory of Mine Occurrences and Prospects (IMOP) database maintained by the Missouri Department of Natural Resources (MDNR) and (2) historical plat maps of the area. All areas are primarily rural residential, with a number of commercial businesses present, generally along the state highways (Ref. 7, p. 4). Field activities associated with the 2010 EPA Site Inspection (SI) evaluated various su rface water body segments located within the greater Big River watershed (Big Watershed -- 07140104) in the general site vicinity (Ref. 4, pp. 1-2); however, the focus of the Hazard Ranking System (HRS) sco ring of the Washington County Lead District - Furnace Creek is centered on the 71-acr e Furnace Creek tailings pile (Source 1) (Ref. 6, p. 11; 12, p. 1; 13, p. 1).

The first written record of a lead mine in Missouri was made in 1700 by Father James Gravier, S.J., who noted a lead mining region in what is now Washi ngton County. The first period of continuous lead mining in Missouri began in 1721, when Phillipe Franco is Renault brought slave labor into the area north of Potosi in order to mine the surface and near-surfa ce lead ores. Numerous small mines rapidly opened throughout Washington County and produced as much as 1,500 pounds of ore per day. Activity tapered off after 20 years, with only intermittent production un til 1799. Ore was generally covered from shallow pits; the deepest known shaft in southeastern Washingt on County is 115 feet. Mi ning was often done by farmers who operated small mines during the winter to supplement their income. In 1818, H.R. Schoolcraft noted of Washington County that there we re a great number of "old diggings" in the area (Ref. 6, p. 1).

Early lead miners discarded the barite in waste piles, as it originally had few uses. It became valuable after the Civil War, when it was used as a long-l asting white pigment. In the early 1900s, several thousand people mined barite and lead in Washington County. Small pits and hand mining gave way in 1924 to mechanized mining. Barite mining boomed in 1926, when the mineral was discovered to be a useful weighting agent in oil drilling mud. Washingt on County was the world leader in barite production for a number of years; production started to declin e in 1985 due to competition from Nevada and overseas operations (Ref. 6, p. 1).

Source 1 is located in Study Area 22, which is located in the central portion of the five study areas and covers sections of South State Highway 21 and Furnace Creek and Younker Roads. Source 1 is a documented fishery where individuals consume their catches (Ref. 5, p. 1; 8, p. 1; 10, pp. 1-2). Although identified as an intermittent on the U.S. Geological Survey (USGS) topographic quadrangle, an unnamed stream was observed flowing south-southeasterly fo r about 1.5 miles from the southwestern portion of Source 1 toward Furnace Creek; Furnace Creek merges with the Big River approximately 1.25 miles downstream from the confluence of the unnamed creek a nd Furnace Creek (Ref. 3, p. 1; 5, p. 1). Based on actual field observations and documented in phot ographs, Source 1 and the extending unnamed creek from its southwestern portion, within the surface water target distance limit (TDL) are perennial (Ref. 13, p. 1; 17, pp. 1, 4, 5). The remainder of the TDL is located in the Big River (Ref. 13, p. 1).

Washington County is located in East Central Missouri. It is bordered on the north by Franklin County, on the east by Jefferson and St. Francois Counties, on the south by Iron County, and on the west by Crawford County. The climate in Washington County, Missouri, is characterized by cool winters and hot summers. The average daily maximum temperature is 88 degrees Fahrenheit (°F) in the summer and

7

### 31°F during the winter. The mean annual precip itation is about 39.33 inches, with 47 percent (18.7 inches) falling between April and September (Ref. 24, pp. 3-4).

Existing analytical data for the W ashington County Lead District – Furnace Creek site being evaluated in support of this HRS documentation record and its su rrounding mining related inves tigations include data obtained by EPA and MDNR at different dates. A comprehensive removal assessment (RA) report and the 2010 Site Inspection (SI) are ongoing. The continuing RA is outside of the 2010 Site Inspection (SI) (Ref.5; 14; 16; 29).

MDNR conducted a macroinvertebrate bioassessment a nd fine sediment study of the upper Big River in Washington County in 2001 and 2002. The study found a Furnace Creek area mine had contributed dissolved barium and copper to Big River (Ref. 27, p. 25-26).

EPA conducted a Site Inspection (SI) at the site in 2010. The general SI objective was to further evaluate the nature of contaminants associated with potential source areas at the Washington County Lead District – Furnace Creek site and its surroundings based on the IMOP database. Samp les were collected in January and April 2010 as part of the SI. Soil samples collected from the 72-acre Furnace Creek Tailings Pile (Source 1) – Soil 1, Soil 2, Soil 3, and Soil 4 – contained arsenic at concentrations ranging from 3.15 to 133 milligrams per kilogram (mg/kg); barium at c oncentrations ranging from 1,940 J to 5,180 J mg/kg (“J” denotes an estimated value); copper at concentr ations ranging from 6.21 to 17.3 mg/kg; lead at concentrations ranging from 88.3 J to 67,000 J mg/kg; and zinc at concentrations ranging from 49.7 to 115 mg/kg (Ref. 11, p. 8; 12, p. 1; 14, pp. 3, 6, 7 8; 15, p. 1; 19, pp. 1-4; 20, p. 4). Additional surface water samples water samples (4876-101, 4876-102, an d 4876-103) were collected from it during April 2010. In these samples, no arsenic or cadmium w as reported above the detection limit; barium was reported at concentrations ranging from 921 to 967 μ g/L; and lead was reported at concentrations ranging from 2.87 J to 5.73 J μ g/L (Ref. 11, p. 8; 16, pp. 3, 5, 6; 21, p. 1; 22, p. 3-5). Past mining activities have impacted Source 1, which is a documented fishery an d sensitive environment (wetland) subject to Level II contamination (Ref. 8, p.1; 10, pp. 1-2; 23, pp. 1-4).

8

### 2.2 SOURCE CHARACTERIZATION

2.2.1 SOURCE IDENTIFICATION

Name of Source : Furnace Creek Tailings Pile Number of Source : 1

Source Type: Pile

Description and Location of Source (with reference to a map of the site): Source 1 (Furnace Creek Tailings Pile) is depicted on Figures 1 and 2 (Ref. 12 , p. 1; 13, p. 1). The Furnace Creek Plant itself, however, is located at a different location in Wash ington County; based on the information provided by the MDNR it was operated by Holly Mining Company and was logged separately in the IMOP database (Ref 6, p. 10). The IMOP database is based upon the U.S. Bureau of Mines Mineral Industry Location System (MILS) database for Missouri. The majority of its information was updated in the late 1970s and early 1980s (Ref. 25, p. 1). Source 1 location is noted in the Public Land Survey System (PLSS) format in Table 1 (Ref. 6, pp. 1, 4, 5, 11). The geographi c coordinates for the approximate center of the tailings pond, Source 1, are 37° 50’ 25.91’’ North and 90° 47’ 58.40’’ West (Refs. 3; 12, p. 1; 13, p. 1). Evidence observed during the 2010 Site Inspection field activities indicated that no engineering controls or containment features were present at the tailings pond (Ref. 17, pp. 1-4).

Table 1 Name Description Commodity Acres Status

Furnace Creek Tailing Pond Furnace Creek Tailings Pond Southern 1⁄2 of Southeastern 1⁄4 of Section 24 Township 36 North and Range 10 East Barite 71 Tailings pond - water Processing area - idle

Source: Ref. 3, p. 1; 6, p. 11; 17, pp. 1-4



### Contaminants commonly associated with mining distri cts are heavy metals. Hazardous metals, arsenic, barium, copper, lead, and zinc were found at Source 1 during the SI investigation (Ref. 14, pp. 6, 8; 15, p. 1). Observations documented during sampling effort s indicated materials found in Source 1 were mine tailings including tiff materials (Ref. 5, p. 1; 22, p. 1- 2). In addition, Reference 12 depicts the footprint of Source 1, as documented by MDNR during its 208 Strategy Study from 1982. Features associated with the area were mapped by the Missouri Division of Ge ology and Land Survey (DGLS) and department of Environmental Quality (DEQ) in the early 1980s as part of a project referred to as the 208 project. The 208 project was completed in 1982, and it delineated areas of non-coal mined lands, tailings ponds and plant areas. These maps were developed from t opographic maps, orthophoto quadrangles and personal communications. The maps were digitized using a commercial GIS system, using the topographic base as a guide. While improving the coverage over that derived from the topographic maps, these maps also pre-dated cessation of barite mining in the area (Ref. 6, pp. 4-6).

The first written record of a lead mine in Missouri was made in 1700 by Father James Gravier, S.J., who noted a lead mining region in what is now Washi ngton County. The first period of continuous lead mining in Missouri began in 1721, when Phillipe Franco is Renault brought slave labor into the area north of Potosi in order to mine the surface and near-surfa ce lead ores. Numerous small mines rapidly opened throughout Washington County and produced as much as 1,500 pounds of ore per day. Activity tapered off after 20 years, with only intermittent production un til 1799. Ore was generally covered from shallow pits; the deepest known shaft in southeastern Washingt on County is 115 feet. Mi ning was often done by

9

### 10 farmers who operated small mines during the winter to supplement their income. In 1818, H.R. Schoolcraft noted of Washington County that there we re a great number of "old diggings" in the area (Ref. 6, p. 1).

Early lead miners discarded the barite in waste piles, as it originally had few uses. It became valuable after the Civil War, when it was used as a long-l asting white pigment. In the early 1900s, several thousand people mined barite and lead in Washington County. Small pits and hand mining gave way in 1924 to mechanized mining. Barite mining boomed in 1926, when the mineral was discovered to be a useful weighting agent in oil drilling mud. Washingt on County was the world leader in barite production for a number of years; production started to declin e in 1985 due to competition from Nevada and overseas operations (Ref. 6, p. 1).

This source is being evaluated as “pile” because it was designed and used as a disposal site for tailings processed by washer plants (Ref. 18, pp. 7-9). These disposal ponds allowed the tailings to dewater, but they were not constructed to treat water. Tailings ar e a mixture of water and finely ground rock that is left over once mineral concentrate is removed and perm anently stored in large area usually located in a natural hollow or valley. Often tailings embankment (b arrier) is built of rock and other materials at the low end of the valley to contain the tailings material . Once there the finely ground rock and water that together make up tailings separate, and when the tailings settle to the bottom, the balance water accumulate to from a tailings pond (Ref. 26, pp. 1-2). Whereas, the overburden made up of soil, gravel, and loose materials that cover the surface of a mine s ite are typically stored in large piles and used after mining to landscape the area (Ref. 26, p. 1). As show n in pictures included in Reference 17 (Ref. 17, pp. 1-3), piles and tailings are all in contact with the pon d and get inundated during we t weathers (Ref. 5, p. 1). This source is shown on the Belgrade, Missour i Quadrangles (Refs. 3; 12, Figure 1). Figure 1 (Reference 12) presents an extrapolat ed area associated with the tailings pile with overlays showing the locations of some surface water and sediment samp les collected in relative downgradient locations (Ref. 12, p. 1).

### 2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

All source samples were collected at Source 1 and co ntain “wastes” associated tailings piles, and adjacent areas that contain comingled resultant overburden. The sampling associated with Source 1 was conducted in January and April 2010. Associated results are presented in Table 2 (solids/soil) and Table 3 (surface water) below. The samples were collected from the pond (Ref. 12, p. 1) and followed the EPA approved Quality Assurance Project Plan (Ref. 11, pp. 2, 8). All data packages for the Washington County Lead District – Furnace Creek site (ASR# 4757 and ASR# 4876) were out sourced to a CLP laboratory for the metals analyses using the CLP Statement of Work (SOW) ILM05.4 (Ref. 29, p. 1).

Table 2

Source 1 Analytical Data Washington County Lead Di strict – Furnace Creek, Wa shington County, Missouri Date: January and March 2010 EPA Sample Number/Samp le Designation Sampling Depth (feet) Sample Quantitation Limit (mg/kg) Hazardous Substance* Concentration (mg/kg) Reference

ASR 4757 (January 2010; Ref. 14)

4757-1/SOIL 1 1.49 Arsenic 3.15 4757-1/SOIL 1 29.8 Barium 1,940 J
4757-1/SOIL 1 3.72 Copper 7.17
4757-1/SOIL 1 1.49 Lead 88.3 J 4757-1/SOIL 1 8.93 Zinc 49.7 Ref. 12, p. 1; 14, pp. 3, 6, 7 8; 15, p. 1; 19, p. 1; 20, p. 4; 28, p. 1; 29, p. 1

4757-2/SOIL 2 1.14 Arsenic 10.2 4757-2/SOIL 2 68.6 Barium 3,000 J 4757-2/SOIL 2 2.86 Copper 17.3 4757-2/SOIL 2 1.14 Lead 238 J 4757-2/SOIL 2 6.86 Zinc 115 Ref. 12, p. 1; 14, pp. 3, 6, 7 8; 15, p. 1; 19, p. 2; 20, p. 4; 28, p. 1; 29, p. 1

4757-3/SOIL 3 1.01 Arsenic 9.16 4757-3/SOIL 3 60.9 Barium 3,260 J 4757-3/SOIL 3 2.54 Copper 7.45 4757-3/SOIL 3 1.01 Lead 160 J 4757-3/SOIL 3 6.09 Zinc 106 Ref. 12, p. 1; 14, pp. 3, 6, 7 8; 15, p. 1; 19, p. 3; 20, p. 4; 28, p. 1; 29, p. 1

4757-4/SOIL 4 1.06 Arsenic 133 4757-4/SOIL 4 106 Barium 5,180 J 4757-4/SOIL 4 2.65 Copper 6.21 4757-4/SOIL 4 10.6 Lead 67,600 J 4757-4/SOIL 4 0-4

6.36 Zinc 92.9 Ref. 12, p. 1; 14, pp. 3, 6, 7 8; 15, p. 1; 19, p. 4; 20, p. 4; 28, p. 1; 29, p. 1

ASR 4876 (April 2010; Reference 16) 4876-1/Soil 1 1.63 Arsenic 6.67 4876-1/Soil 1 32.7 Barium 3,780 4876-1/Soil 1 1.63 Lead 299 Ref 16, pp. 3, 5; 21, p. 1; 22, p. 1; 28, p. 1; 29, p. 1; 30, p. 1 4876-2/Soil 2 1.45 Arsenic 10.6 4876-2/Soil 2 28.9 Barium 3,690

4876-2/Soil 2 0-4

1.45 Lead 227 Ref 16, pp. 3, 5; 21, p. 1; 22, p. 2; 28, p. 1; 29, p. 1; 30, p. 1

Notes: EPA United States Envir onmental Protection Agency



### 11J Estimated value: (i) Based on the EPA laboratory valida tion document, the actual J-coded Barium concentration in Table 2 were higher than the reported value (biased low) due to low recoveries of Barium in the laboratory control samples as well as concentration may be lower than the re ported value (biased high) due to the serial dilution percent differences being above the cont rol limits and (ii) the actual J-coded Lead concentration in Table 2 were lower than the reported value (biased high) due to the serial dilution percen t differences being above the control limits. However, in both cases analytes were positivel y identified (Ref. 14, pp. 6-7). mg/kg Milligrams per kilogram * Includes a pollutant or contaminant

Table 3

Source 1 Analytical Data Washington County Lead District– Furnace Creek, Washington County, Missouri Surface Water Samples in μ g/L ASR 4876 (March 20 10; Reference 16) EPA Sample Number/Sample

Designation Sampling Depth (feet) Sample Quantitation Limit ( μ g/L) Hazardous Substance Concentration ( μ g/L) Reference

4876-101/SW 101 10 Barium 921

4876-101/SW 101 1 Lead 5.73 J Ref 11, p. 8; 16, pp. 3, 5; 21, p. 1; 22, p. 3; 28, p. 1; 29, p. 1; 30, p. 1 4876-102/SW 102 10 Barium 965

4876-102/SW 102 1 Lead 3.96 J Ref 11, p. 8; 16, pp. 3, 5; 21, p. 1; 22, p. 4; 28, p. 1; 29, p. 1; 30, p. 1 4876-103/SW 103 10 Barium 967

4876-103/SW 103 Not Applicable

1 Lead 2.87 J Ref 11, p. 8; 16, pp. 3, 6; 21, p. 1; 22 p. 5; 28, p. 1; 29, p. 1; 30, p. 1

Notes:

EPA United States Envir onmental Protection Agency J Estimated value; the actual J-coded Lead concentration in Table 3 were higher than the reported value (biased low) due to the serial dilution percent difference bei ng above the control limits (Ref. 16, p. 4)
μ g/L Microgram per liter NA Not Available SW Surface Water



### The sampling was conducted in accordance with EPA Region 7 Standard Operating Procedure (SOP) 4230.17, SOP 4230.08, and SOP 4231.2012 for surface water, sediment, and soil, respectively. The Chain of Custody was maintained as directed by EPA Region 7 SOP 2420.04 and samples were accepted according to EPA Region 7 SOP 2420.01 (Ref. 11, p. 5) . The review and verification was performed by a qualified analyst as described in Region 7 EPA SOPs 2430.06 and 2430.12 (Ref. 11, p. 7). The sediment, soil, and water samples were analy zed in accordance to analytical met hods as stipulated by EPA Region 7 SOPs 3122.03, and 3122.4, respectively (Ref. 11, p. 8). The table included in Reference 28 includes sample identification numbers in Tables 2 and 3 of this documentation record as they correlate with Figure 1 (Reference 12) and Figure 2 (Reference 13); Reference 28 also includes correlating sample designations for field sheets and analytical data packages.

12

### 2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Table 4

Source 1 Containment
Containment Description Containment Factor Value Reference

Gas release to air: - NS -- Particulate release to air: - NS -- Release via ground water NS -- Release via overland migration and/or flood: Source 1 has no maintained engineered cover or run on and/or run off control system, functioning leachate collection and removal system. 10 Ref. 1, Table 4-2; 5, p. 1; 17, pp. 1-4; 22, pp. 1-5

Notes:

NS Not Scored



### 13

### 14 2.2.4 HAZARDOUS WASTE QUANTITY

2.4.2.1.1. Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A, as required in Section 2.4.2.1.1 of the HRS. As a result, the evaluation of Hazardous Waste Qu antity proceeds to evaluate Tier B, hazardous wastestream quantity (Ref. 1, p. 51590-51591).

Hazardous Constituent Quantity Value: NS

2.4.2.1.2. Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Ti er B, as required in Section 2.4.2.1.2 of the HRS. As a result, the evaluation of Hazardous Waste Quantity proceeds to evaluate Tier C, volume (Ref.1, p. 51591).

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3. Volume

The information available is not sufficient to evaluate Ti er C, as required in Section 2.4.2.1.3 of the HRS. As a result, volume is assigned a value of zero, an d the evaluation of Hazardou s Waste Quantity proceeds to evaluate Tier D, area (Ref. 1, p. 51591).

Volume Assigned Value: 0

2.4.2.1.4. Area

Description Based on the estimated value provided by MDNR, the area of Source 1 is 71 acres (Ref. 6, p. 11). Therefore, based on the HRS Table 2-5 on page 51591, the total acres (71) was multiplied by 43,560 square feet; the total square feet (3,092,760) was divi ded by 13 to arrive at the Hazardous Waste Quantity Value of 237,904.62.

Table 5 Source Type Area Units References Pile 3,092,760 Square feet 1, Table 2-5; 6, p. 11



### Sum (ft 2 

### ): 3,092,760 Equation for Assigning Value (Table 2-5): A/13

Area Assigned Value: 237,904.62 (Ref. 1, p. 51591)

2.4.2.1.5. Source Hazardous Waste Quantity Value

Highest assigned value assigned from HRS Table 2-5: 237,904.62 (Ref. 1, p. 51591)

NS = Not Scored

### SUMMARY OF SOURCE DESCRIPTIONS

Table 6

Summary of Source 1 Descriptions
Containment Factor Value by Pathway

Surface Water (SW) Air Source

No. Source Hazardous

Waste Quantity

Value Source Hazardous Constituent

Quantity Complete? (Y/N) Ground Water (GW) (Table 3-2) Overland/ flood (Table

4-2) GW to SW (Table

3-2) Gas (Table

6-3) Particulate (Table 6-9)

1 237,904.62 No Not Scored 10 Not Scored Not Scored Not Scored



### Description of Other Possible Sources/Sites

The focus of EPA Region 7 sampling activities in the Washington County Lead District – Furnace Creek area has been at residential homes (Ref. 7, pp. 8-10, 20, 1079-1534). Numerous barite tailings ponds are found throughout the area; however, only Source 1 has be en evaluated as a source in the HRS scoring of the Washington County Lead District – Furnace Creek site. Further remedial investigations may be warranted to establish inter-watersh ed contamination. It should be noted, however, tailings ponds were generally created near head of valleys, at a higher el evation than the general topography in the area; in turn, this placed the tails and process water at higher elev ations than the water table for the majority of the area. As they are visible in topography based ma ps, the tailings and process water were often located upgradient of major streams in the area, some of which may be losing streams (Ref. 3, pp. 1, 2; 12, p. 1; 13, p. 2; 6, pp. 1, 9-14).

In Washington County, a number of tailings piles have been identified but have not yet been sampled to characterize the hazardous constituents associated with them. A number of known large former mining operations are included in pages 9 through 14 of Refe rence 6. The EPA Superfund lead investigation sampling in Washington County indicates an area-wi de surface soil and ground water contamination as documented during past EPA Region 7 investigations and listed in Reference 7 (Ref. 7, pp. 8-10, 20, 1079-1534). For scoring purposes, only Source 1 or Furnace Creek Tailings Pond has been included in this HRS evaluation; however, it is important to note that other sources, such as the Irondale Mine Area, West Fork Mine Area, Hopewell Mine Area, and Fo rker Diggings, were sampled during the 2010 SI (Ref. 5, pp. 1-2). Sample 4757-11 collected at the Irondale Mine area contained lead up to 195,000 J mg/kg (Ref. 14, p. 10; 15, p. 2; 12, p. 1)

In addition to the large operations described above, at one time Washington County was host to hundreds and possibly thousands of small mines that we re worked by hand (Ref. 6, pp. 1-4).

15

### 4.0 SURFACE WATER MIGRATION PATHWAY

4.1 OVERLAND/FLOOD MIGRATION COMPONENT

4.1.1.1 Definition of Hazardous Substance Mi gration Path for Overland/Flood Component

The nearby towns and communities are located on the Big watersheds, as defi ned by USGS Hydrologic Unit 07140104. Numerous creeks and rivers drain associated watersheds in this area, primarily draining towards the Big River. The Big River is the primary surface water feature in the general vicinity of the site (Ref. 3, pp. 1; 4, p. 1-2; 12, p. 1; 13, p. 1).

For the HRS scoring purposes, documented observed rel eases to the surface water migration pathway are associated with Source 1, which is a pond with a docu mented fishery and wetland targets; Source 1 is a pond meeting the definition of lake for HRS scoring . As such, Source 1 is a documented human food chain fishery (Ref. 8, p. 1; 10 pp. 1-2). HRS qua lified wetland areas are contained within Source 1 (Ref. 23, p. 1-3; 12, p. 1). As the source is located within the surface water body being evaluated as a target, the probable point of entry (PPE) is identified at the most upstream location of the Source; the PPE is depicted on Figure 2 (Reference 13). A perennial unnamed creek exits the s ource from its southwestern portion (Ref. 3; 5, p. 1; 12, p. 1; 13, p. 1). It flows from the pond a distance of 1.5 miles where it joins Furnace Creek. Furnace Creek flows south for 1.25 mil es where it merges with the Big River. The Big River flows east and makes up the remainder of the in -water segment. The 15-mile target distance limit (TDL) is near the Washington and St. Francois county line (Ref. 12, p. 1; 13, p. 1).

16

### 4.1.2.1 LIKELIHOOD OF RELEASE

4.1.2.1.1 Observed Release

An observed release by direct observation can be documented to the surface water migration pathway.

Direct Observation

- Basis for Direct Observation By definition, the deposition of the tailings cont aining hazardous substances into a surface water body qualifies as an observed release by direct observation to surface water (Ref. 1, Section 4.1.2.1.1, p. 51609; Section 2.2.2 and Table 2 of this HRS documentation record). A fishery and wetland are located within the boundaries of Source 1 (Ref. 8, p. 1; 10 pp. 1-2; 23). This observed release by direct observation is also supported by photographs taken during in January 2010 and the MDNR Strategy 208 Study (Ref. 1, Section 4.1.2.1.1, p. 51609; 6, pp. 3-5, 11; 17, pp. 1-4).

- Hazardous Substances in the Release Hazardous substances associated with Source 1 were identified during the January 2010 and April 2010 sampling data included in References 14, 15, and 16. Analysis of the samples by EPA laboratory confirmed the presence of arsenic, barium, copper, lead , and zinc. The analytical data from these samples are summarized in Table 2 in Section 2.2.2.

In accordance with Section 4.1.2.1.1 (Ref. 1, p. 51609), an observed release factor value of 550 is assigned below and on line 1 of Table 4-1. Potential to release is not evaluated.

17

### Attribution

Source 1 is a tailings pile with an associated pond (Ref . 3, p. 1; 6, p. 11; 17, pp. 1-4). Tailings piles associated with mining waste are designed and used as disposal sites for tailings processed by washer plants (Ref. 18, pp. 7-9). Source 1 contains a documented fishery where individuals consume their catches. Source 1 also contains wetlands within its boundary (Ref. 5, p. 1; 8, p. 1; 10, pp. 1-2; 23). Hazardous substances associated with Source 1 are arsenic, barium, copper, lead, and zinc.

Lead and barium mining in the Furnace Creek area of Washington County has a long history dating back hundreds of years. The first written record of a lead mine in Missouri was made in 1700 by Father James Gravier, S.J., who noted a lead mining region in what is now the Washington County. The first period of continuous lead mining in Missouri began in 1721, when Philippe Fran cois Renault brought slave labor into the area north of Potosi, in order to mine th e surface and near-surface lead ores. Numerous small mines rapidly opened throughout Washington County. In the late 18 th 

### and early 19 th 

### century mining was often undertaken by farmers who operated small mines during the winter to supplement their income. Early miners discarded the barite in waste piles, as back then it had little economic value. It became valuable after the Civil War, when it was used as a long-lasting white pigment. In the early 1900s, several thousand people mined barite and lead in W ashington County. Barite mining boomed in 1926, when the mineral was discovered to be useful weigh ting agent in oil drilling mud (Ref. 6, pp. 1). As Reference 17 (Ref. 17; pp. 1-2) photographs show ther e are no liners or engineering controls to mitigate release from the source. Mechanized and subsistence hand mining in the site area continued clearly into the 20 th 

### century. Many of the later large mining compan ies reworked lands that had experienced hand mining for lead or barite, as considerable barite ore remained in the material left between the pits and shafts. In some cases, the older pits were used as an exploration guide (Ref. 6, p. 4). A physiochemical study conducted by MDNR in 2001/2002 indicated tota l recoverable barium concentrations near the confluence of Furnace Creek and the Big River increased by more than three-fold from the upstream stations (Ref. 27, p. 17). The study further conc luded that there are few known mines in the upper reaches of the Big River (upstream from the conflu ence of Furnace Creek and the Big River) that may influence the river’s community (Ref. 27, pp. 5).

Likelihood of Release Value: 550

18

### 4.1.3.2 Waste Characteristics

4.1.3.2.1 Toxicity/Persistence/Bioaccumulation

Table 7

Hazardous Substance Source Number/ OR Toxicity Factor Value Persistence Factor Value 1 Bioaccumulation Value 2 Toxicity/Persistence/ Bioaccumulation

Factor Value 2 (Table 4-16) 3 Reference

Arsenic 1/OR 10,000 1 5 50,000 2, pp. 2, 3 Barium 1/OR 10,000 1 500 5 × 10 6 2, pp. 4, 5 Copper 1/OR 0 1 500 0 2, pp. 8, 9

Lead 1/OR 10,000 1 5 50,000 2, pp. 10, 11 Zinc 1/OR 10 1 5.0 50 2, pp. 12, 13

Notes:

1 - Persistence factor value for lake was used.
2 - Freshwater bioaccumulation factor values were used.
3 - Table found in Reference 1, page 51619 OR Observed Release



### Barium was found at this site at concentrations know n to potentially cause adverse effects (Ref. 9, pp. 1, 4; 2, pp. 4-5; Tables 2 and 3 of the HRS documentation record; Ref. 13; Ref. 14, p. 23). The compound with the highest toxicity/persistence/bioaccumulation factor value is barium. Its assigned value of 5 × 10 6 

### is entered below and on line 15 of Table 4-1.

4.1.3.2.2 Hazardous Waste Quantity

Table 8

Source Number Source Hazardous Waste Quantity Value (Section 2.4.2.1.5) Is Source Hazardous Constituent Quantity Data Complete? (yes/no) 1. Furnace Creek Tailings Pond 237,904.62 no Sum of Values: 237,904.62



### A hazardous waste quantity value of 10,000 is selecte d from Table 2-6 of the HRS (Ref. 1, p. 51591) based on the Source Hazardous Waste Quantity Value of 237,904.62. This value is entered below and on line 16 of Table 4-1.

19

### 20 4.1.3.2.3 Waste Characteristics Factor Category Value

A waste characteristics product is computed by multiplying the toxi city/persistence factor value by the hazardous waste quantity factor value (the product of which is subject to a maximum of 1 × 10 8 

### ) and then multiplying that number by the bioaccumulation potential factor value. This product (subject to a maximum of 1 × 10 12 

### ) is then entered into Table 2-7 (Ref. 1, p. 51592) to obtain a waste characteristics factor category value. Barium yields the highest waste characteristics factor value.

Toxicity/persistence factor value × hazardous waste quantity factor value: 1 × 10 8 

### 10,000 × 10,000 = 1 × 10 8



### (Toxicity/persistence x hazardous waste quantity) × bioaccumulation potential factor value: 5 × 10 10


### 1 × 10 8 

### × 500 = 5 × 10 10



### Waste Characteristics Value: 320

Therefore, 320 was entered on line 17 of Table 4-1.

### 4.1.3.3 Human Food Chain Threat-Targets

Furnace Creek Tailings Pond or Source 1 is regularly fished. The total fishery production is unknown but is greater than zero because fish are known to be consum ed annually (Ref. 8, p. 1; 10, p. 1-2). Hazardous substances with a bioaccumulation value of 500 or gr eater have been documented in this fishery (See Section 4.1.3.2.1 of this HRS documentation record). Therefore, it is an HRS- qualified human food chain fishery (Ref. 1, Section 4.1.3.3, p. 51620).

4.1.3.3.1 Food Chain Individual

There is an observed release of hazardous substances having a bioaccumulation factor value (BCFV) of 500 or greater to the watershed. A known fishery is s ubject to Level II actual contamination. Therefore, a food chain individual factor value of 45 is assigned. This value is entered on line 18 of the Table 4-1.

Food Chain Individual Value: 45

4.1.3.3.2 Population

4.1.3.3.2.1 Level I Concentrations

No zone of Level I contamination has been identified for any fishery at this time, because no known fish tissue samples have been collected.

4.1.3.3.2.2 Level II Concentrations

An observed release by direct observation has been do cumented in Source 1 (see Section 4.1.2.1.1 of this HRS documentation record). Because the PPE to surface water is located in Source 1 and the fishery is located wholly within Source 1, the entire fishery is evaluated as actually contaminated at Level II concentrations (see HRS Section 4.1.1.2). The tota l fishery production is unknown but is greater than zero because fish are known to be consumed annually; a value of 0.03 is assigned for Level II Concentrations Factor Value (Ref. 1, HRS Table 4-18; 8, p. 1). This value is entered on line 9b of Table 4-1.

Level II Concentrations Factor Value: 0.03

4.1.3.3.2.3 Potential Human Food Chain Contamination

Not scored.

21

### 4.1.4.2 WASTE CHARACTERISTICS

4.1.4.2.1 Ecosystem Toxicity/Persistence/Bioaccumulation

Table 9

Hazardous Substance Source Number/OR Ecosystem Toxicity Factor Value 1 Persistence Factor Value 3 Ecosystem Toxicity/ Persistence Factor Value (Table 4-20) 2 Reference

Arsenic 1/OR 10 1 10 2, pp. 2, 3 Barium 1/OR 1 1 1 2, pp. 4, 5 Copper 1/OR 1,000 1 1,000 2, pp. 8, 9

Lead 1/OR 1,000 1 1,000 2, pp. 10, 11 Zinc 1/OR 10 1 10 2, pp. 12, 13

Notes:

1 Freshwater ecotoxicity values used from Reference 2. 2 Table found in Reference 1, page 51622. 3 Persistence factor value for lakes used. OR Observed Release

Table 10

Hazardous Substance Ecosystem Toxicity/ Persistence Factor Value EcoBioaccumulation Factor Value 1 (Section 4.1.4.2.1.3) 2 Ecosystem Toxicity/ Persistence/ Bioaccumulation Factor Value (Table 4-21) 3

Arsenic 10 5,000 50,000 Barium 1 500 500 Copper 1,000 5,000 5X10 6

Lead 1,000 50,000 5 × 10 7
Zinc 10 50,000 5X10 5

Notes:

1 Freshwater bioaccumulation factor values used from Reference 2. 2 Reference 1, page 51622. 3 Table found in Reference 1, page 51623.



### An ecosystem toxicity/persistence/bioaccu mulation factor value of 50,000,000 (5 × 10 7 

### ) is assigned from the table above based on lead. This value is entered below and on line 23 in Table 4-1.

22

### 4.1.4.2.2 Hazardous Waste Quantity

Table 11

Source Number Source Hazardous Waste Quantity Value (Section 2.4.2.1.5) Is Source Hazardous Constituent Quantity Data Complete? (yes/no) 1. Furnace Creek Tailings Pond 237,904.62 no Sum of Values: 237,904.62



### A hazardous waste quantity value of 10,000 is selected from Table 2-6 of the HRS rule (Ref. 1, p. 51591) based on the Source Hazardous Waste Quantity Value of 237,904.62. This value is entered below and on line 24 of Table 4-1 found on page 5 of this documentation record.

4.1.4.2.3 Waste Characteristics Factor Category Value

A waste characteristics factor value is computed by first multiplying the ecotoxicity/persistence factor value by the hazardous waste quantity factor value (t he product of which is subject to a maximum of 1 × 10 8 

### ) and then multiplying that number by the bioaccu mulation potential factor value. This product (subject to a maximum of 1 × 10 12 

### ) is then entered into Table 2-7 (Ref. 1, p. 51592) to obtain a waste characteristics factor category value. Of the haza rdous substances in Section 4.1.4.2.1 of the HRS documentation record, lead produces the highest value. This value is entered below and on line 25 in Table 4-1.

Ecosystem toxicity/persistence factor value × hazardous waste quantity factor value: 1 × 10 7 

### 1,000 × 10,000 = 1 × 10 7



### (Ecosystem toxicity/persistence × hazardous waste quantity) × bioaccumulation potential factor value: 5 × 10 11


### 1 × 10 7 

### × 50,000 = 5 × 10 11



### Waste Characteristics Factor Value: 560

23

### 4.1.4.3 ENVIRONMENTAL THREAT - TARGETS

4.1.4.3.1 Sensitive Environments

4.1.4.3.1.1 Level I Concentrations

No zones of Level I contamination have been identified.

4.1.4.3.1.2 Level II Concentrations

An observed release by direct observation has been do cumented in Source 1 (see Section 4.1.2.1.1 of this HRS documentation record). Because the PPE to surface water is located in Source 1 and the wetland is located wholly within Source 1, the wetland is ev aluated as actually contaminated at Level II concentrations (see HRS Section 4.1.1.2).

Wetlands

A USFWS defined wetland is located in Source 1 (R efs. 23, pp. 1-2). Wetlands on the eastern and western portion of the source have been classified by the USFWS as follows:

• Wetland on the eastern side of Source 1: PEMCh -- Palustrine, Emergent, Seasonally Flooded, Diked/Impounded, (Ref. 23, pp. 2-3).

• Wetland on the western side of Source 1: PEMFh -- Palustrine, Emergent, Semipermanently Flooded, Diked/Impounded, (Ref. 23, pp. 2-3).

Table 12 Wetland Wetland Frontage Reference Perimeter of the wetland (east) 983.23 feet (0.19 mile) 23, p. 1, 4 Perimeter of the wetland (west) 2,736.58 feet (0.52 mile) 23, p. 1, 4 Total Wetland Frontage: 3,719.81 (0.71 mile)



### A wetland value is assigned from Table 4-24 (Ref. 1, p. 51625).

Wetland Value: 25

Sum of Sensitive Environments Value + Wetland Value: 25

This value is entered below and on Table 4-1 line 26b.

Sensitive Environments Level II Value: 25

4.1.4.3.1.3 Potential Contamination

Potential targets in were not scored because they do not contribute significantly to the pathway score.

24