HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD COVER SHEET 

Name of Site: Walker Machine Products, Inc. 

EPA ID No.: TNN000410124 

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 

 John Nolen, Remedial Project Manager 

U.S. Environmental Protection Agency, Region 4 

61 Forsyth Street, S.W., 11th Floor 

Atlanta, Georgia 30303 

(404) 562-8750 

HRS Documentation Record: 

 Shanna Davis, Site Manager 

Tetra Tech, Inc. 

1955 Evergreen Boulevard, Ste. 300 

Duluth, Georgia 30096 

(678) 775-3109 

Pathways, Components, or Threats Not Scored

The surface water migration, soil exposure, and air migration pathways were not scored in this Hazard 

Ranking System (HRS) documentation record because the ground water migration pathway is sufficient 

to qualify the site for the National Priorities List (NPL). These pathways are of concern to the U.S. 

Environmental Protection Agency (EPA) and may be considered during future evaluation. 
1

HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD

Name of Site: Walker Machine Products, Inc. 

EPA Region: 4 

Date Prepared: December 2013 

Street Address of Site*: 459 Washington Street 

City, County, State, Zip: Collierville, Shelby County, Tennessee 38017 

General Location in the State: Southwestern portion of state 

Topographic Map: Collierville, Tennessee 1975 

Latitude: 35o 02' 29.72" North 

Longitude: 89o 39' 12.49" West 

The coordinates above for Walker Machine Products, Inc. (Walker Machine) were measured from Source 

No. 1 soil sampling location WM090411SB, located in the western portion of the property, about 15 feet 

east of the manufacturing building (Ref. 4). 

* The street address, coordinates, and contaminant locations presented in this HRS documentation 

record identify the general area the site is located. They represent one or more locations EPA considers to 

be part of the site based on the screening information EPA used to evaluate the site for NPL listing. EPA 

lists national priorities among the known “releases or threatened releases” of hazardous substances; thus, 

the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous 

substance has been “deposited, stored, disposed, or placed, or has 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 (CERCLA). Accordingly, EPA contemplates that the preliminary 

description of facility boundaries at the time of scoring will be refined as more information is developed 

as to where the contamination has come to be located. 

Pathway Pathway Score 

Ground Water Migration 100.00

Surface Water Migration NS

Soil Exposure NS

Air Migration NS

HRS SITE SCORE 50.00

Note: 

NS Not scored
2

WORKSHEET FOR COMPUTING HRS SITE SCORE 

S Pathway S

2

Pathway

Ground Water Migration Pathway Score (Sgw) 100.00 10,000

Surface Water Migration Pathway Score (Ssw) NS NS

Soil Exposure Pathway Score (Ss) NS NS

Air Migration Pathway Score (Sa) NS NS

S

2

gw + S2sw + S2s + S2a 10,000

(S

2

gw + S2sw + S2s + S2a) / 4 2,500

√ (S

2

gw + S2sw + S2s + S2a) / 4 50.00

Note: 

NS = Not scored
3

Table 3-1 --Ground Water Migration Pathway Scoresheet 

Aquifer Evaluated: Memphis Sand 

Factor Categories and Factors Maximum Value Value Assigned

Likelihood of Release to an Aquifer: 

1. Observed Release 550 550

2. Potential to Release:

2a. Containment 10 NS

2b. Net Precipitation 10 NS

2c. Depth to Aquifer 5 NS

2d. Travel Time 35 NS

2e. Potential to Release [lines 2a(2b + 2c + 2d)] 500 NS

3. Likelihood of Release (higher of lines 1 and 2e) 550 550

Waste Characteristics:

4. Toxicity/Mobility (a) 10,000

5. Hazardous Waste Quantity (a) 10

6. Waste Characteristics 100 18

Targets:

7. Nearest Well 50 9

8. Population:

8a. Level I Concentrations (b) 0

8b. Level II Concentrations (b) 0

8c. Potential Contamination (b) 870.2

8d. Population (lines 8a + 8b + 8c) (b) 870.2

9. Resources 5 NS

10. Wellhead Protection Area 20 5

11. Targets (lines 7 + 8d + 9 + 10) (b) 884.2

Ground Water Migration Score for an Aquifer: 

12. Aquifer Score [(lines 3 x 6 x 11)/82,500]c100 100.00

Ground Water Migration Pathway Score:

13. Pathway Score (Sgw), (highest value from line 12 for all 

aquifers evaluated)c

100 100.00

Notes: 

NS = Not scored 

a

 = Maximum value applies to waste characteristics category 

b

 = Maximum value not applicable 

c

 = Do not round to nearest integer
Washington Street

File: L:\TTEMI-05-003-0156_Walker_Mac

Walker Machine Products

459 Washington St. 

Collierville, TN

4
Location of Former AST

Oil/Water Separator

Witt International, Inc.

Approximate Location of TCE Drums

Storage building

Manufacturing Building

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WM22-0612-SBD

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Washington St.

Haley St.

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7
8

REFERENCES 

1. U.S. Environmental Protection Agency (EPA). Hazard Ranking System, Title 40 Code of Federal 

Regulations Part 300, 55 Federal Register 51532. December 14, 1990. 138 Pages. Available online 

at: http://www.epa.gov/superfund/sites/npl/hrsres/index.htm#HRS_Rule. 

2. EPA. Superfund Chemical Data Matrix (SCDM). March 31, 2012. Excerpt, 56 Pages. A complete 

copy of SCDM is available at: http://epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm.

3. Tetra Tech, Inc. (Tetra Tech). 4-Mile Radius. Base map taken from U.S. Geological Survey 

(USGS) 7.5 Minute Series Topographic Quadrangle Maps: Collierville, Tennessee, 1975; Rossville, 

Tennessee, 1981; Mt. Pleasant, Mississippi-Tennessee, 1971; Byhalia Northwest, MississippiTennessee, 1971. Scale 1:24,000. 1 Map. 

4. Tetra Tech. Project Note to File with Attachment. Subject: Coordinates for the Walker Machine 

Products, Inc., property. Attachment: Google Earth Map. November 6, 2012. 2 Pages. 

5. Walker Machine Products, Inc (Walker Machine). Letter with Attachment. From: Harold D. 

Walker, Jr., President. To: Tom Yates, Tennessee Department of Health and Environment. 

Attachment: Hazardous Waste Notification. September 29, 1987. 3 Pages. 

6. EPA. Facility Registry System. Facility Detail Report. Site Name: Walker Machine Products, Inc. 

 Accessed on November 6, 2012. 2 Pages. Accessed on-line at: 

http://iaspub.epa.gov/enviro/fii_query_dtl.disp_program_facility?p_registry_id=110004961676. 

7. Tennessee Division of Remediation (TDOR). Memorandum to File. Subject: Walker Machine 

Products, Collierville, Shelby County. February 10, 2010. 1 Page. 

8. Tennessee Department of Environment and Conservation (TDEC). Expanded Site Investigation 

Report, Walker Machine Products. Prepared for EPA. September 15, 2012. Excerpt. 21 Pages. 

9. Assessor of Property. Shelby County, Tennessee. Property Address: 459 Washington Street. 

 Accessed on November 6, 2012. 1 Page. Accessed on-line at: 

http://www.assessor.shelby.tn.us/PropertySearchDetail.aspx?id=C0245 

00188&ReturnUrl=http%3a%2f%2fwww.assessor.shelby.tn.us%2fPropertySearch.aspx%3fStreetNu

mber%3d459%26StreetName%3dWashington%26FirstName%3d%26LastName%3d%26ParcelID%

3d%26Business%3d. 

10. Register of Deeds. Shelby County, Tennessee. Property Address: 459 Washington Street. Accessed 

on November 6, 2012. 1 Page. Aerial modified by Tetra Tech to show the approximate location of 

Walker Machine. Modified March 5, 2013. Accessed on-line at: 

http://gis.register.shelby.tn.us/index.php?task=addressQuery&address=459

washington&gg=shelby&roads=on&par=on&orthos2010=on&f=layersfolder&b=info. 

11. TDEC. Pre-Comprehensive Environmental Response, Compensation, and Liability Information 

System (CERLIS) Screening Assessment Report, Walker Machinery. Revision 1. Prepared for 

EPA. June 25, 2008. 133 Pages. 

12. TDEC. Site Investigation Report, Walker Machine Products. Prepared for EPA. August 22, 2011. 

Excerpt. 178 Pages. 

13. TDOR. Project Note to File. Subject: Meeting with Mr. Harold Langley. September 10, 2012. 

1 Page. 
9

14. State of Tennessee. County of Shelby. Warranty Deed. Property Address: 459 Washington Street, 

Collierville, Tennessee. April 22, 2005. 1 Page. 

15. Langley Wire Cloth Products, Inc. About Us. Accessed on November 6, 2012. 1 Page. Accessed 

 on-line at: http://www.langleywirecloth.com/about%20us.htm. 

16. Walker Machine. Letter. From: Harold D. Walker, Jr., President. To: James E. Fleming, Tennessee 

Department of Health and Environment. September 29, 1987. 2 Pages. 

17. Tennessee Department of Health and Environment. Office Correspondence. Subject: Notice of 

Violation, September 8, 1987, Walker Machine Products, Inc., TND982115016. From: Paul 

Patterson. To: J. Tom Tiesler. February 29, 1988. 1 Page. 

18. Tennessee Department of Labor. Division of Occupational Safety and Health. Notice of Alleged 

Safety or Health Hazards. Employer Name: Walker Machine Products, Inc. September 18, 1987. 

1 Page. 

19. TDEC. Site Reassessment Report. Walker Machine Products. Prepared for EPA. June 16, 2010. 

168 Pages. 

20. Tetra Tech. Letter with Attachment. Subject: Final Product Deliverable for Membrane Interface 

Probe and Direct Push Technology Investigation, Walker Machine Products. To: John Nolen, 

Remedial Project Manager, EPA. From: John Snyder, START III Field Team Leader. November 

20, 2012. 143 Pages. 

21. EPA. Memorandum with Attachment. Subject: Final Analytical Report, Project 12-0528, Walker 

Machine Products, Inc. From: Jeffrey Hendel, Quality Assurance Section Chemist. To: John Nolen. 

Attachment: Final Analytical Data. August 3, 2012. 76 Pages. 

22. TDEC. Site Inspection Report. Witt International, Inc. Prepared for EPA. Not Dated. 131 Pages. 

23. Witt. Central Station, Air Handling Units, Brochure 1110. Not Dated. 8 Pages. 

24. Witt. About Witt. Accessed November 13, 2012. 1 Page. Accessed on-line at: 

http://witt.htpgusa.com/about-us/about-witt. 

25. Witt. Heat Transfer Products Group History. Accessed November 13, 2012. 1 Page. Accessed on- 

 line at: http://witt.htpgusa.com/about-us/htpg-history. 

26. EPA, Office of Research and Development. Technical Protocol for Evaluating Natural Attenuation 

of Chlorinated Solvents in Ground Water, EPA/600/R-98/128. September 1998. 248 Pages. 

27. Park and Illenberger, Inc. Profile of the Screw Machine Products and Turned Parts Industry. 

Prepared for the Cleveland Advanced Manufacturing Program under Contract to the Energy 

Environment and Manufacturing Project of the Technology Reinvestment Program. Not dated. 

84 Pages. 

28. U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic 

Substances and Disease Registry (ATSDR). Toxicological Profile for Tetrachloroethylene. 

September 1997. 316 Pages. 

29. ATSDR. ToxFAQs for 1,1-dichloroethene. U.S. Department of Health and Human Services, Public 

Health Service. September 1995. 2 Pages. 
10

30. ATSDR. ToxFAQs for Trichloroethylene. U.S. Department of Health and Human Services, Public 

Health Service. July 2003. 2 Pages. 

31. U.S. Department of Health and Human Services, Public Health Service, ATSDR. Toxicological 

Profile for 1,2-dichloroethene. August 1996. 195 Pages. 

32. ATSDR. ToxFAQs for 1,1,1-trichloroethane. U.S. Department of Health and Human Services, 

Public Health Service. July 2006. 2 Pages. 

33. U.S. Department of Health and Human Services, Public Health Service, ATSDR. Toxicological 

Profile for 1,1-dichloroethane. December 1990. 114 Pages. 

34. EPA, Region 4 Science and Ecosystem Support Division (SESD). Operating Procedure for Soil 

Sampling, Number SESDPROC-300-R1. Effective Date: November 1, 2007. 22 Pages. 

35. EPA, Region 4 SESD. Analytical Support Branch Laboratory Operations and Quality Assurance 

Manual. January 6, 2011. 205 Pages. 

36. Tetra Tech. Record of Telephone Conversation. Subject: Data Review, Validation, and Verification 

Conducted at the EPA SESD. Between Jessica Vickers, Quality Assurance Manager, Tetra Tech, 

and Nardina Turner, EPA Region 4 Superfund Sample Control and Quality Assurance Coordinator. 

July 25, 2013. 1 Page. 

37. Tetra Tech. Record of Telephone Conversation. Subject: Definitions of Minimum Reporting Limit, 

Contract Required Quantitation Limit, and Sample Quantitation Limit. Between Jessica Vickers, 

Quality Assurance Manager, Tetra Tech, and Nardina Turner, EPA Region 4 Superfund Sample 

Control and Quality Assurance Coordinator. July 25, 2013. 1 Page. 

38. EPA Office of Emergency and Remedial Response. Using Qualified Data to Document and 

Observed Release and Observed Contamination. Quick Reference Fact Sheet EPA-540-F-94-028. 

November 1996. 18 Pages. 

39. Tetra Tech. Project Note to File. Subject: Summary of J-Qualified Data. November 16, 2012. 

2 Pages. 

40. TDEC, Division of Remediation. Project Note to File with Attachment. Subject: 2007, 2011, and 

2012 Sampling Methods and Facilities in the Immediate Vicinity of Walker Machine. Attachment: 

Chain of Custody and Supplemental Information. August 19, 2013. 3 Pages. 

41. Tetra Tech. Project Note to File with Attachment. Subject: Chain of Custody Records from 2009, 

2011, and 2012. Attachment: Chain of Custody Records from 2009, 2011, and 2012. November 16, 

2012. 12 Pages. 

42. EPA. Contract Laboratory Program (CLP) Statement of Work (SOW) for Organics Analysis, MultiMedia, Multi-Concentration, SOM01.2. Updated April 2007. 747 Pages. Accessed on-line at: 

http://www.epa.gov/superfund/programs/clp/som1.htm#pdf.

43. Tetra Tech. Review of Field Quality Control Samples, Walker Machine Products. August 8, 2012. 

10 Pages. 

44. Tennessee Century Farms. Shelby County. Accessed November 21, 2012. 8 Pages. Page 2 was 

modified by Tetra Tech to show the approximate location of Walker Machine. Modified February 

19, 2013. Accessed on-line at: http://www.tncenturyfarms.org/shelby_county/. 
11

45. Criner, J. H., P-C. P. Sun, and D. J. Nyman. Hydrology of Aquifer Systems in the Memphis Area, 

Tennessee. Geological Survey Water Supply Paper 1779-O. 1964. 66 Pages. 

46. U.S. Geological Survey (USGS). Hydrogeology and Ground-Water Flow in the Memphis and Fort 

Pillow Aquifers in the Memphis Area, Tennessee. Water-Resources Investigations Report 89-4131. 

By: J.V. Brahana and R.E. Broshears. 2001. 61 Pages. Figures 1, 5, 10, and 11 were modified by 

Tetra Tech to show the approximate location of Walker Machine. Modified February 19, 2013. 

47. Moore, Gerald K. Geology and Hydrology of the Claiborne Group in Western Tennessee. 

Geological Survey Water-Supply Paper 1809-F. 1965. 59 Pages. Plates 3, 4, and 5 were modified 

by Tetra Tech to show the approximate location of Walker Machine. Modified February 19, 2013. 

48. USGS. Potential for Leakage Among Principal Aquifers in the Memphis Area, Tennessee. WaterResources Investigations Report 85-4295. By: D.D. Graham and W.S. Parks. 1986. 51 Pages. 

49. USGS. Geology and Ground-Water Resources of the Memphis Sand in Western Tennessee. WaterResources Investigations Report 88-4182. By: W.S. Parks and J.K. Carmichael. 1990. 33 Pages. 

Figures 2 and 3 were modified by Tetra Tech to show the approximate location of Walker Machine. 

Modified February 19, 2013. 

50. USGS. Hydrogeology and Preliminary Assessment of the Potential for Contamination of the 

Memphis Aquifer in the Memphis Area, Tennessee. Water-Resources Investigations Report 90-

4092. By: William S. Parks. 1990. 47 Pages. Plate 1 was modified by Tetra Tech to show the 

approximate location of Walker Machine. Modified February 19, 2013. 

51. Tetra Tech. Project Note to File. Subject: Missing Confining Unit at Walker Machine. November 

26, 2012. 1 Page. 

52. USGS. Effects of Urban Development on the Aquifers in the Memphis Area, Tennessee. WaterResources Investigations Report 82-4024. By: David D. Graham. 1982. 25 Pages. 

53. USGS. Altitude of Potentiometric Surface, Fall 1985, and Historic Water-Level Changes in the 

Memphis Aquifer in Western Tennessee. Water-Resources Investigations Report 88-4180. By: W. 

S. Parks and J. K. Carmichael. 1990. 12 Pages. Plate 1 was modified by Tetra Tech to show the 

approximate location of Walker Machine. Modified August 7, 2013. 

54. Tetra Tech. Letter with Attachment. Subject: Soil Boring/Well Logs, Well Survey, and Field 

Logbook Notes. From: Sandra Harrigan, START III Project Manager. To: John Nolen, Remedial 

Project Manager, EPA. May 12, 2009. 31 Pages. 

55. TDEC, Division of Water Supply. Tennessee Source Water Assessment Report. August 2003. 

85 Pages. 

56. EPA Region 4 SESD. Operating Procedure for Soil Sampling, Number SESDPROC-300-R2. 

Effective Date: December 20, 2011. 25 Pages. Accessed on-line at: 

http://www.epa.gov/region4/sesd/fbqstp/Soil-Sampling.pdf. 

57. EPA Region 4 SESD. Operating Procedure for Groundwater Sampling, Number SESDPROC-301-

R1. Effective Date: November 1, 2007. 30 Pages. 

58. EPA Region 4 SESD. Operating Procedure for Groundwater Sampling, Number SESDPROC-301-

R2. Effective Date: October 28, 2011. 32 Pages. 
12

59. EPA. Summary of State Biennial Reports of Wellhead Protection Program Progress, October 1995 

through September 1997. 111 Pages. Accessed on-line at: 

http://www.epa.gov/safewater/sourcewater/pubs/qrg_wellhead_doc2.pdf. 

60. Tetra Tech. Record of Telephone Conversation with Attachment. Subject: Town of Collierville 

Water Department. Between Shanna Davis, Environmental Scientist, Tetra Tech, and Tim Overly, 

Director of Public Utilities, Town of Collierville. Attachment: Critical Infrastructure Worksheet. 

January 9, 2013. 3 Pages. 

61. Town of Collierville. Water Quality Report, 2011. 3 Pages. Accessed on-line at: 

http://www.collierville.com/images/stories/public/waterqualityreport2011.pdf. 

62. Tetra Tech. Project Note to File with Attachments. Subject: 2011 Site Investigation at the Walker 

 Machine Property. Attachments: Photographs. February 6, 2013. 4 Pages. 

63. EPA Region 4 SESD. Field Branches Quality System and Technical Procedures, Operating 

Procedure for Waste Sampling, Number SESDPROC-302-R0. Effective Date: February 5, 2007. 

22 Pages. 

64. Tetra Tech. Project Note to File with Attachments. Subject: EPA Envirofacts Facility Detail 

Reports for Facilities Located Near Walker Machine. Attachments: EPA Envirofacts Facility Detail 

Reports, Superfund Information System Search Results, Toxic Release Inventory Search Results, 

NPL sites in Collierville, Shelby County Tennessee Search Results, Superfund Site Progress 

Profiles, and Google Earth Image. July 23, 2013. 30 Pages. 

65. TDEC. Electronic Mail Correspondence. Subject: Walker Request. From: Don Sprinkle, TDEC. 

To: Shanna Davis, Environmental Scientist, Tetra Tech. January 24, 2013. 1 Page. 

66. TDEC. Project Note to File. Subject: Conversation with Mike Bradley USGS, Re: Contamination 

Found to the South of Walker. September 7, 2012. 1 Page. 

67. Tetra Tech. Project Note to File with Attachments. Subject: Town of Collierville Source Water 

Assessment. Attachments: Individual Source Water Assessment for the Town of Collierville 

Wellfields. February 5, 2013. 11 Pages. 

68. Rock Tenn. Tennessee. Accessed March 26, 2013. 3 Pages. Accessed on-line at: 

http://bipac.net/rocktenn/Maps/Tennessee.pdf. 

69. EPA. Office of Research and Development. National Risk Management Research Laboratory. 

Mississippi Embayment Regional Ground Water Study. Report EPA 600/R-10/130. January 2011. 

188 Pages. 

70. Tetra Tech. Project Note to File with Attachments. Subject: Town of Collierville Municipal Well 

 Logs. Attachments: Municipal Well Logs for Wells 102 and 103. July 9, 2013. 5 Pages. 

71. Tetra Tech. Project Note to File. Subject: Ground Water Flow at Walker Machine. July 16, 2013. 

 1 Page. 

72. Tetra Tech. Project Note to File with Attachments. Subject: Resource Conservation and Recovery 

Act (RCRA) Site Detail Reports. Attachments: RCRA Site Detail Reports for Constar Inc. and 

Durand Raute Corp. August 13, 2013. 21 Pages. 
13

73. Tetra Tech. Electronic Mail Correspondence. Re: TDEC’s Definition of MDL and MQL. 

Attachments: TDEC Definition of MDL and MQL. From: Sandra Harrigan, Project Manager, Tetra 

Tech. To: Rhonda Mitchell, Environmental Chemistry Manager, Tennessee Department of Health, 

Jackson Regional Laboratory. September 20, 2013. 3 Pages. 
14

SITE DESCRIPTION

Walker Machine Products, Inc. (Walker Machine), is located at 459 Washington Street in Collierville, 

Shelby County, Tennessee (Ref. 5) (see Figure 1 of this HRS documentation record). More specifically, 

the geographic coordinates, as measured from sampling location WM090411SB, located about 15 feet 

east of the manufacturing building, are latitude 35o 02' 29.72" north and longitude 89o 39' 12.49" west 

(Ref. 4). The EPA identification number, as recorded in the Comprehensive Environmental Response, 

Compensation, and Liability Information System (CERCLIS) database, is TNN000410124 (Ref. 6). The 

property consists of one parcel of land covering an area of about 5 acres (Refs. 9; 10). Walker Machine is 

bounded by Washington Street to the north, a vacant, wooded lot to the east, railroad tracks to the south, 

and the former Witt International, Inc. (Witt International), facility to the west (Refs. 4; 7; 10) (see Figure 

2 of this HRS documentation record). 

The Walker Machine property includes a metal and concrete manufacturing building surrounded by 

concrete parking and storage pads to the north and south, a metal storage building to the east, grass to the 

west, and gravel cover in between the two buildings (Refs. 7; 8, p. 1) (see Figure 2 of this HRS 

documentation record). The property is fenced along the western boundary, but access is unrestricted to 

the north, east, and south (Ref. 8, p. 1). A circular-shaped concrete pad is located south of the 

manufacturing building. This pad once contained an aboveground storage tank (AST). Adjacent to the 

concrete pad is a drainage pit that was used to contain spills from the AST (Refs. 4; 8, p. 1; 11, p. 2). An 

oil-water separator (below ground tank) is located about 35 feet south of the manufacturing building 

(Refs. 8, p. 1; 11, p. 132; 12, p. 3). Dilapidated drums (one drum was labeled trichloroethylene [TCE])

along with other drum parts were located in the wooded area on the property, south of the manufacturing 

building (Refs. 12, pp. 52, 68; 62, pp. i, 1, 2, 3). The property is currently owned and operated by 

Langley Wire Cloth Products, Inc. (Langley) (Refs. 9; 13; 15). 

Two sources have been identified on the Walker Machine property. Source No. 1 consists of 

contaminated soil resulting from automated machine screw manufacturing operations (such as 

unpermitted discharges and spills). Specifically, grab samples used to characterize Source No. 1 were 

collected in the vicinity of (1) the manufacturing building, (2) the oil/water separator and former AST, 

and (3) the dilapidated TCE drum located south of the manufacturing building (Refs. 12, pp. 3, 52, 54, 68; 

20, p. 71; 62, pp. i, 1, 2, 3). Source No. 2 is an oil/water separator (below ground tank) located about 35 

feet south of the manufacturing building (Refs. 11, p. 132; 12, p. 3) (see Figures 2 and 3 of this HRS 

documentation record). Chlorinated solvents have been documented in Source Nos. 1 and 2 (see Section 

2.2.1, Source Nos. 1 and 2 and Figure 2 of this HRS documentation record). Ground water underlying 

and in the vicinity of these sources contains 1,1,1-trichloroethane (TCA); 1,1-dichloroethane (DCA); 

tetrachloroethylene (PCE) and TCE and their breakdown products (1,1-dichloroethylene [DCE] and cis1,2-DCE) at concentrations greater than background levels, indicating that a release of hazardous 

substances has occurred to the ground water migration pathway, as documented in Section 3.0 of this 

HRS documentation record. About 46,000 people are served by 10 municipal drinking water wells 

located within a 4-mile radius of Source Nos. 1 and 2; these wells are evaluated as potential 

contamination targets (see Section 3.3 of this HRS documentation record). 

OPERATIONAL AND REGULATORY HISTORY 

Walker Machine manufactured precision fabricated metal products (also referred to as automated machine 

screw products) from 1953 until about 2002 (Refs. 5, pp. 1, 3; 8, p. 4; 19, p. 1; 27, p. 2). Langley 

purchased the property from Walker Machine in 2005 and began operations in 2006 (Refs. 13; 14). 

Langley manufactures wire cloth and perforated metal products, with an emphasis on strainers and filters 

(Ref. 15). Langley used small amounts of TCE until 2012 and all solvents used were reclaimed and 

recycled (Refs. 13; 40). 

Three critical materials are needed for the manufacture of automated screw products: raw materials, 

cutting oils and coolants, and solvents (Ref. 27, pp. 35, 36, 37). Raw materials, including carbon steel, 

copper and brass, and alloy steel, are converted to component parts and metal chips. A broad range of 
15

machining operations are performed, configuring the raw material (bar stock) into a component part (Ref. 

27, pp. 37, 38). During machining operations, cutting oils and coolants are used to reduce friction, hold 

down temperature, protect the work piece from corrosion, and flush away chips (Ref. 27, p. 39). The 

chips generated from machining operations are recovered, treated to remove oils, and sold to scrap dealers 

(Ref. 27, p. 38). Once component parts are produced, solvents are used to clean the parts and to ensure 

that the parts are free of oil, film, and chips (Ref. 27, p. 45). Typical solvents used in the industry include 

mineral spirits, 1,1,1-TCA, PCE, and TCE (Ref. 27, pp. 46, 47). 

Walker Machine used mineral spirits to clean metal parts and 1,1,1- TCA to clean brass parts (Refs. 5; 

16). Once the solvent became too contaminated with cutting oil and metal shavings, the spent solvent 

was poured into a filter medium that removed the oil and metal shavings from the solvent (Refs. 5; 17). 

The recycled solvent was stored in a 500-gallon AST and reused for cleaning metal parts (Refs. 5; 17). 

Other solvents including PCE and TCE were typically used to clean and degrease automated machine 

screw products (Ref. 27, pp. 46, 47). 

In September 1987, the Tennessee Department of Labor, Division of Occupational Safety and Health 

(DOSH), conducted an inspection at the Walker Machine facility. DOSH personnel observed spent 

solvent that had been discharged to the ground and into a sewer drain located in the rear of the building 

(Ref. 18). Solvent tanks located inside the manufacturing building were not properly grounded (Ref. 18). 

Walker Machine also used an oil/water separator located near the former AST (Refs. 11, p. 2; 12, p. 3). 

The oil/water separator is currently located on the property, but is not used by Langley (Ref. 8, p. 4). In 

July 2007, a sample collected from material inside the oil/water separator contained cis-1,2-DCE and 

vinyl chloride (Refs. 11, pp. 6, 7, 113, 114; 40).

During the 2011 site investigation (SI), a drum labeled TCE along with an unlabeled drum and drum parts 

were observed in the wooded area on the property, about 115 feet south of the manufacturing building 

(Refs. 12, pp. 52, 68; 62, pp. i, 1, 2, 3). The drums were rusted and flattened (Ref. 62, p. i). 

PREVIOUS INVESTIGATIONS 

Between 2007 and 2012, numerous investigations were conducted at Walker Machine and the adjacent 

Witt International. In 2007, the Tennessee Department of Environment and Conservation (TDEC) 

conducted a pre-CERCLIS screening investigation at Walker Machine. The investigation included 

sampling surface and subsurface soil, ground water, and waste (Ref. 11, p. 6). The samples contained 

chlorinated solvents at concentrations exceeding background levels (Ref. 11, pp. 9, 10, 11). The ground 

water sample collected from the monitoring well located closest to the oil/water separator (WM-MW-03) 

contained PCE at 590 micrograms per liter (μg/L); TCE at 48 μg/L; trans-1,2-DCE at 1.1 μg/L; 1,1-DCE 

at 25 μg/L; 1,1,1-TCA at 12 μg/L; and 1,1-DCA at 9.9 μg/L (Refs. 11, pp. 10, 14; 12, p. 3). 

In March 2009, TDEC conducted a site inspection at Witt International in an effort to discover possible 

releases from Witt International and to determine if ground water contamination was migrating from 

Walker Machine (Ref. 22, p. 1). Subsurface soil samples collected from monitoring well locations on 

Witt International did not contain chlorinated solvents at concentrations exceeding their minimum 

reporting limits (MRL) (Ref. 22, pp. 7, 8, 9, 92, 93, 96, 97, 104 through 109). Ground water samples 

were collected from monitoring wells installed at Walker Machine, as well as from newly installed Witt 

International monitoring wells. Ground water samples collected from the Witt International monitoring 

wells contained chlorinated solvents, but at concentrations significantly lower than the ground water 

sample collected from Walker Machine monitoring well WM-MW-03 (Ref. 22, pp. 9, 10, 11). 

Monitoring well MW-MW-03 is located adjacent to the oil/water separator and former AST (Refs. 4; 11, 

p. 2; 22, pp. 8, 11). TDEC concluded that a ground water plume is present under the oil/water separator 

located on the Walker Machine property and that the plume is traveling generally downgradient toward 

and underneath the Witt International property (Ref. 22, p. 10). 
16

As a result of contamination delineation efforts, subsequent investigations at Walker Machine also 

include sampling monitoring wells installed at Witt International. Table 1 lists the previous sampling 

investigations, including the hazardous substances detected in the samples collected. 

TABLE 1: Summary of Previous Investigations

Agency Investigation Date

Samples 

Collected

Chemicals of 

Concern 

Detected in 

Source No. 1 References

TDEC Pre-CERCLIS 

Screening 2007

Surface soil

Subsurface soil

Ground water

Waste

PCE

TCE

cis-1,2-DCE

trans-1,2-DCE

vinyl chloride

1,1-DCE

1,1,1-TCA

1,1-DCA

11, pp. 6, 9, 

10, 11, 35

TDEC Site 

Reassessment 2010 Ground water

PCE

TCE

cis-1,2-DCE

1,1-DCE

1,1,1-TCA

1,1-DCA

19, pp. i, 5, 8, 

11

TDEC Site 

Investigation 2011 Subsurface soilGround water

PCE

TCE

cis-1,2-DCE

1,1-DCE

1,1,1-TCA

1,1-DCA

12, pp. i, 5, 8, 

11, 13

TDEC Expanded Site 

Investigation 2012 Subsurface soilGround water

PCE

TCE

cis-1,2-DCE

1,1-DCE

1,1,1-TCA

1,1-DCA

8, pp. i, 6, 9, 

11; 20, p. 71

Notes: 

CERCLIS Comprehensive Environmental Response Compensation and Liability Information System 

DCA Dichloroethane 

DCE Dichloroethene 

No. Number 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

TDEC Tennessee Department of Environment and Conservation 

In 2011, TDEC conducted an SI at Walker Machine (Ref. 12, pp. 1, 5). SI activities included collection 

of subsurface soil and ground water samples from permanent monitoring wells (Ref. 12, pp. 5). All 

samples were analyzed for volatile organic compounds (VOCs) (Ref. 12, pp. 80, 82, 118, 120). Soil 

sample depths ranged from 1 to 24 feet below ground surface (bgs) (Ref. 12, p. 54). Soil samples 

contained PCE (up to 430 micrograms per kilogram [μg/kg]); TCE (up to 57J μg/kg [“J” indicates the 

result is estimated]); cis-1,2-DCE (up to 31J μg/kg); 1,1-DCE (up to 3.6 μg/kg); 1,1,1-TCA (up to 2.8J

μg/kg); and 1,1-DCA (up to 16 μg/kg) (Ref. 12, pp. 13, 54). Ground water samples were collected from 

permanent monitoring wells installed at depths ranging from 66 to 79 feet bgs (Refs. 19, pp. 104 to 107; 

40; 54, pp. 3 to 6). The ground water samples contained PCE (up to 1,500 micrograms per liter [μg/L]); 
17

TCE (up to 120 μg/L); cis-1,2-DCE (up to 120 μg/L); 1,1-DCE (up to 210 μg/L); 1,1,1-TCA (up to 72 

μg/L); and 1,1-DCA (up to 87 μg/L) (Ref. 12, pp. 11, 64). The highest concentrations of PCE, TCE, and 

cis-1,2-DCE were detected in ground water samples WM030411GW (WM-MW-03) and 

WM0502411GW (WM-MW-05) located near the oil/water separator (Ref. 12, pp. 3, 9, 11, 64). 

In 2012, TDEC conducted an expanded site investigation (ESI) at Walker Machine (Ref. 8, p. 6). ESI 

activities included collection of subsurface soil and ground water samples from permanent and temporary 

monitoring wells (Refs. 8, pp. 9, 11; 20, pp. 1, 71). All samples were analyzed for VOCs (Ref. 21, pp. 1, 

4). Soil samples were collected between 12 and 65 feet bgs and contained PCE (up to 530 μg/kg) and 

1,1-DCE (up to 15J μg/kg) (Ref. 20, p. 71). Ground water samples were collected from permanent and 

temporary monitoring wells installed at depths ranging from 66 to 85 feet bgs (Refs. 19, pp. 104 to 107; 

20, pp. 83 to 88; 40; 54, pp. 3 to 6). The ground water samples contained PCE (up to 2,000 μg/L); TCE 

(up to 150 μg/L); cis-1,2-DCE (up to 160 μg/L); 1,1-DCE (up to 220 μg/L); 1,1,1-TCA (up to 72 μg/L); 

and 1,1-DCA (up to 97 μg/L) (Ref. 20, pp. 72, 77). The highest concentrations of these constituents were 

detected in samples WM03-0612-GW and WM05-0612-GW, located near the oil/water separator (Refs. 

8, p. 11; 19, p. 3; 20, pp. 72, 77). 
18 Source Characterization 

2.2 SOURCE CHARACTERIZATION

2.2.1 SOURCE IDENTIFICATION

Number of source: 1 

Name of source: Contaminated soil 

Source Type: Contaminated soil 

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

Source No. 1 is an area of contaminated soil resulting from automated machine screw operations 

(unpermitted discharges and spills). Specifically, grab samples used to characterize Source No. 1 were 

collected in the vicinity of (1) the manufacturing building, (2) the oil/water separator and former AST, 

and (3) a dilapidated TCE drum located about 115 feet south of the manufacturing building (Refs. 12, pp. 

3, 15, 52, 54, 68; 20, p. 71; 62, pp. i, 1, 2, 3) (see Figures 2 and 3 of this HRS documentation record). 

The soil samples contain overlapping hazardous substances (chlorinated solvents) related to facility 

processes; however, the extent and continuity of contamination between discrete areas in Source No. 1 is 

not known (Refs. 5, p. 1; 12, pp. 52, 68; 16; 20, p. 71; 27, pp. 46, 47) (see Figure 3 and Tables 2 and 3 of 

this HRS documentation record). 

The property was used for the manufacturing of precision fabricated metal parts (also referred to as 

automated machine screw products) from 1953 until about 2002 (Refs. 5, pp. 1, 3; 8, p. 4; 19, p. 1; 27, p. 

2). Mineral spirits were used to clean metal parts and 1,1,1-TCA was used to clean brass parts (Refs. 5, p. 

1; 16). Spent solvent was stored in a 500-gallon AST and reused for cleaning metal parts (Refs. 5, p. 1; 

17). Other solvents including PCE and TCE were typically used to clean and degrease automated 

machine screw products (Ref. 27, pp. 46, 47). 

In September 1987, DOSH conducted an inspection at the facility. DOSH personnel observed spent 

solvent that had discharged to the ground and into a sewer drain located in the rear of the building (Ref. 

18). Solvent tanks located inside the manufacturing building were not properly grounded (Ref. 18). 

In 2011, a rusted and flattened drum labeled TCE was observed in the southern wooded area of the 

Walker Machine property. Another drum and miscellaneous drum parts were also found in the same area 

(Refs. 12, pp. 52, 68; 62, pp. i, 1, 2, 3). PCE and TCE are commonly used to degrease metal parts and 

have been found in subsurface soil samples collected from Source No. 1 (Refs. 12, pp. 54, 88, 89, 90, 93, 

94, 103, 108, 114; 20, pp. 71, 75). Breakdown products of PCE and TCE include 1,1-DCE, and cis-1,2-

DCE (Ref. 26, p. 24). 1,1-DCA is a breakdown product of 1,1,1-TCA (Ref. 33, pp. 53, 58). 

In 2011 and 2012, TDEC collected subsurface soil samples from Source No. 1 at depths ranging from 1 to 

30 feet bgs. The samples contained PCE; TCE; cis-1,2-DCE; 1,1-DCE; 1,1,1-TCA; and 1,1-DCA (Refs. 

12, pp. 54, 88, 89, 90, 93, 94, 103, 108, 114; 20, pp. 71, 75) (see Tables 2 and 3 of this HRS 

documentation record). Background subsurface soil samples were not collected for Source No. 1 during 

the 2011 investigation (Refs. 12, pp. 13, 54). PCE; TCE; cis-1,2-DCE; 1,1-DCE; 1,1,1-TCA; and 1,1-

DCA do not occur naturally (Refs. 12, pp. 13, 54; 20, p. 71; 21, pp. 57 through 61; 28, p. 1; 29; 30; 31, 

pp. 7, 113; 32 ). Therefore, their presence in Source No. 1 indicates that a release has occurred or is 

occurring at the Walker Machine property. 
19 Source Characterization 

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

April 2011 SI – Soil Samples 

Subsurface soil samples listed in Table 2 were collected by TDEC during the April 2011 SI (Ref. 12, pp. 

1, 5, 13, 54). The subsurface soil samples were collected at depths ranging from 1 to 24 feet bgs (Ref. 12, 

p. 54). PCE; TCE; cis-1,2-DCE; 1,1-DCE; 1,1,1-TCA; and 1,1-DCA do not occur naturally (Refs. 12, pp. 

13, 54; 20, p. 71; 21, pp. 57 through 61; 28, p. 1; 29; 30; 31, pp. 7, 113; 32). Therefore, their presence in 

the subsurface soil (Source No. 1) indicates that a release has occurred or is occurring at the Walker 

Machine property. 

The Source No. 1 samples were collected in the vicinity of (1) the manufacturing building, (2) the 

oil/water separator and former AST, and (3) the TCE drum located about 115 feet south of the 

manufacturing building (Refs. 12, pp. 3, 15, 52, 54, 68; 20, p. 71; 62, pp. i, 1, 2, 3) (see Figures 2 and 3 of 

this HRS documentation record). Source No. 1 samples were collected using direct-push technology 

(DPT) or hand augers (Ref. 12, p. 13). The subsurface soil samples were collected in accordance with the 

EPA Region 4 Science and Ecosystem Support Division (SESD) Field Branches Quality System and 

Technical Procedures for Soil Sampling, SESDPROC-300-R1, November 2007 (Refs. 34; 40). The 

samples were analyzed for VOCs (EPA Method 8260C) by the EPA Region 4 Analytical Support Branch 

(ASB) in accordance with the ASB Laboratory Operations and Quality Assurance Manual (LOQAM) 

(Refs. 12, p. 80; 35). EPA Region 4 SESD reviewed all data in accordance with the ASB LOQAM and 

EPA methods and guidelines (Refs. 12, p. 80; 36). The MRLs are listed on the analytical data sheets in 

Reference 12, Appendix C. Each MRL is sample-specific and corresponds to the lowest quantitative 

point on the calibration curve; it is adjusted for the amount of sample prepared and any dilutions 

performed. The MRLs are equivalent to sample quantitation limits (SQL), as defined in HRS Section 1.1, 

Definitions (Refs. 1, Section 1.1; 37). The chain-of-custody forms are provided in Reference 41. The 

logbook notes are provided in Reference 12, Appendix B. The locations of the Source No. 1 samples 

listed in Table 2 are provided in Reference 12, page 54. 

TABLE 2: Analytical Results for Source No. 1 – April 2011

Sample ID Location

Hazardous

Substance

Hazardous

Substance 

Concentration MRL References

1 to 3 feet bgs

WM090411SB

About 10 feet east 

of the 

Manufacturing 

Building

PCE 5.7 μg/kg 0.48 μg/kg

12, pp. 54, 

57, 73, 75, 

76, 90; 41, p. 

9

WM090411SB

About 10 feet east 

of the 

Manufacturing 

Building

TCE 7.6 μg/kg 0.48 μg/kg

12, pp. 54, 

57, 73, 75, 

76, 90; 41, p. 

9

WM090411SB

About 10 feet east 

of the 

Manufacturing 

Building

cis-1-2-DCE 6.6 μg/kg 0.48 μg/kg

12, pp. 54, 

57, 73, 75, 

76, 89; 41, p. 

9

WM090411SB

About 10 feet east 

of the 

Manufacturing 

Building

1,1-DCE 3.6 μg/kg 0.48 μg/kg

12, pp. 54, 

57, 73, 75, 

76, 88; 41, p. 

9
20 Source Characterization 

TABLE 2: Analytical Results for Source No. 1 – April 2011

Sample ID Location

Hazardous

Substance

Hazardous

Substance 

Concentration MRL References

WM090411SB

About 10 feet east 

of the 

Manufacturing 

Building

1,1-DCA 16 μg/kg 0.48 μg/kg

12, pp. 54, 

57, 73, 75, 

76, 88; 41, p. 

9

6.5 to 7 feet bgs

WM080411SB

About 50 feet 

southwest of the 

TCE drum

PCE 370 μg/kg 31 μg/kg

12, pp. 54, 

56, 77, 103;

41, p. 7

WM080411SB

About 50 feet 

southwest of the 

TCE drum

TCE 15J (7.11) μg/kg 0.53 μg/kg

12, pp. 54, 

56, 77, 103; 

38, pp. 8, 12; 

39; 41, p. 7

WM080411SBD

About 50 feet 

southwest of the 

TCE drum

PCE 430 μg/kg 29 μg/kg

12, pp. 56, 

77, 108; 41, 

p. 7

WM080411SBD

About 50 feet 

southwest of the 

TCE drum

TCE 57J (27.01) μg/kg 0.50 μg/kg

12, pp. 54, 

56, 77, 108; 

38, pp. 8, 12; 

39; 41, p. 7

7.5 to 8.5 feet bgs

WM110411SB

About 20 feet 

south of the TCE 

drum

PCE 11 μg/kg 0.52 μg/kg

12, pp. 54, 

59, 76, 77, 

116; 41, p. 7

WM110411SB

About 20 feet 

southeast of the 

TCE drum

1,1-DCE 0.67 μg/kg 0.52 μg/kg

12, pp. 54, 

59, 76, 77, 

114; 41, p. 7

WM110411SB

About 20 feet 

southeast of the 

TCE drum

1,1,1-TCA 2.1 μg/kg 0.52 μg/kg

12, pp. 54, 

59, 76, 77, 

114; 41, p. 7

23 to 24 feet bgs

WM120411SB

About 10 feet 

south of the 

Manufacturing 

Building

PCE 5.6 μg/kg 0.47 μg/kg

12, pp. 54, 

60, 73, 75, 

94; 41, p. 9

WM120411SB

About 10 feet 

south of the 

Manufacturing 

Building

TCE 1.6 μg/kg 0.47 μg/kg

12, pp. 54, 

60, 73, 75, 

94; 41, p. 9

WM120411SB

About 10 feet 

south of the 

Manufacturing 

Building

cis-1,2-DCE 2.6 μg/kg 0.47 μg/kg

12, pp. 54, 

60, 73, 75, 

93; 41, p. 9
21 Source Characterization 

Notes: 

( ) Concentration was adjusted in accordance with References 38 and 39 

bgs Below ground surface 

D Duplicate 

DCA Dichloroethane 

DCE Dichloroethylene 

ID Identification 

J Estimated value, unknown bias (Ref. 39). Though not required by the HRS, the value presented 

parenthetically is the concentration obtained by applying EPA fact sheet Using Qualified Data to Document 

an Observed Release and Observed Contamination to show the relative contaminant levels present 

(November 1996) (Refs. 38, pp. 8, 12; 39). 

μg/kg Micrograms per kilogram 

MRL Minimum reporting limit 

No. Number 

PCE Tetrachloroethylene 

SB Subsurface soil 

TCA Trichloroethane 

TCE Trichloroethylene 

WM Walker Machine Products, Inc. 
22 Source Characterization 

June 2012 Expanded Site Investigation

Subsurface soil samples listed in Table 3 were collected by TDEC during the June 2012 ESI (Refs. 8, pp. 

1, 6; 20, p. 71). Background samples (WM21) were collected at depths ranging from 12 to 45 feet bgs 

and are compared with contaminated samples collected at similar depths (Ref. 20, pp. 71, 75). Although 

not required by the HRS, background levels are provided to show the relative increase of contaminant 

levels in the source over background. Subsurface soil sampling station WM21 was selected to represent 

background conditions. This location was chosen to represent background conditions because (1) the soil 

type (clay) at this location was the same as in samples collected from Source No. 1, and (2) the 

background sampling location appeared to have been minimally affected by past facility operations (Ref. 

20, pp. 71, 125, 126, 129, 132). The locations of the background and Source No. 1 samples are provided 

in Reference 20, page 71. 

The background and contaminated soil samples collected from Source No. 1 were collected during the 

same sampling event, in accordance with the same sampling procedures, and from the same soil type 

(predominantly clays) (Refs. 20, pp. 71, 125, 126, 129, 132; 21, p. 4; 34; 41, pp. 2, 4, 6).

The subsurface soil samples were collected in accordance with the EPA Region 4 SESD Field Branches

Quality System and Technical Procedures for Soil Sampling, SESDPROC-300-R2, December 2011 

(Refs. 20, p. 132; 40; 56). The samples were analyzed for VOCs (EPA Method 8260C) in accordance 

with the EPA Contract Laboratory Program (CLP) Statement of Work (SOW) for organic analysis, 

SOM01.2 (Refs. 21, pp. 1, 2; 42). EPA Region 4 reviewed, verified, and validated all data according to 

the CLP SOWs and EPA guidelines (Refs. 21, pp. 1, 2; 36). The MRLs are listed on the analytical data 

sheets in Reference 21. Each MRL is sample-specific and corresponds to the lowest quantitative point on 

the calibration curve; it is adjusted for the amount of sample prepared and any dilutions performed. The 

MRLs are equivalent to SQLs, as defined in HRS Section 1.1, Definitions (Refs. 1, Section 1.1; 37). The 

chain-of-custody forms are provided in Reference 41. The logbook notes are provided in Reference 20, 

Enclosure 6. The locations of the Source No. 1 samples listed in Table 3 are provided in Reference 20, 

page 71. 

TABLE 3: Analytical Results for Source No. 1 – June 2012

Sample ID

Hazardous

Substance

Hazardous

Substance 

Concentration MRL References

Background Subsurface Soil Samples

12 to 13 feet bgs

WM21-0612-SB-A PCE 4.4U μg/kg 4.4 μg/kg 20, p. 125; 21, p. 58; 41, p. 6

WM21-0612-SB-A 1,1-DCE 4.4U μg/kg 4.4 μg/kg 20, p. 125; 21, p. 57; 41, p. 6

44 to 45 feet bgs

WM21-0612-SB-B PCE 4.4U μg/kg 4.4 μg/kg 20, p. 125; 21, p. 61; 41, p. 6

WM21-0612-SB-B 1,1-DCE 4.4U μg/kg 4.4 μg/kg 20, p. 125; 21, p. 60; 41, p. 6

Contaminated Subsurface Soil Samples

19 to 20 feet bgs

WM22-0612-SBD 1,1-DCE 15J (5.53) μg/kg 4.2 μg/kg 20, p. 129; 21, p. 66; 38, pp. 8, 

11; 39; 41, p. 4; 43, pp. 1, 9

WM24-0612-SB PCE 530 μg/kg 260 μg/kg 20, p. 126; 21, p. 76; 41, p. 2

29 to 30 feet bgs
23 Source Characterization 

TABLE 3: Analytical Results for Source No. 1 – June 2012

Sample ID

Hazardous

Substance

Hazardous

Substance 

Concentration MRL References

WM23-0612-SB PCE 12 μg/kg 4.4 μg/kg 20, p. 125; 21, p. 70; 41, p. 6

WM23-0612-SB 1,1-DCE 6.3 μg/kg 4.4 μg/kg 20, p. 125; 21, p. 69; 41, p. 6

WM23-0612-SBD PCE 14 μg/kg 3.9 μg/kg 20, p. 125; 21, p. 73; 41, p. 6

WM23-0612-SBD 1,1-DCE 7.3 μg/kg 3.9 μg/kg 20, p. 125; 21, p. 72; 41, p. 6

Notes: 

( ) Concentration was adjusted in accordance with References 38, pp. 8, 11; 39; 43, pp. 1, 9. 

A Subsurface soil sample collected from 12 to 13 feet bgs 

B Subsurface soil sample collected from 44 to 45 feet bgs 

bgs Below ground surface 

D Duplicate 

DCE Dichloroethylene 

ID Identification 

J Estimated value, unknown bias (Ref. 39). Though not required, the value presented parenthetically is the 

concentration obtained by applying EPA fact sheet Using Qualified Data to Document an Observed Release 

and Observed Contamination (November 1996) to show the relative increase in contaminant levels over 

background (Refs. 38, pp. 8, 11; 39; 43, pp. 1, 9).

μg/kg Micrograms per kilogram 

MRL Minimum reporting limit 

No. Number 

PCE Tetrachloroethylene 

SB Subsurface soil 

U The analyte was not detected at or above the reporting limit (Ref. 21, p. 5). 

WM Walker Machine Products, Inc. 
24 Source Characterization 

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Samples collected from Source No. 1 contained PCE; TCE; cis-1,2-DCE; 1,1-DCE; 1,1,1-TCA; and 1,1-

DCA (see Tables 2 and 3 of this HRS documentation record). Source No. 1 consists of an area of 

contaminated soil in the vicinity of (1) the manufacturing building, (2) the oil/water separator and former 

AST, and (3) the TCE drum located about 115 feet south of the manufacturing building (Refs. 12, pp. 3, 

15, 52, 54, 68; 20, p. 71; 62, pp. i, 1, 2, 3). A liner was not observed during sampling activities for the 

2011 SI and the 2012 ESI (Refs. 12, pp. 56, 57, 59, 73, 75, 76, 77; 20, pp. 125, 126, 129). Therefore, a 

containment factor value of 10, as noted in Table 4, was assigned for the ground water migration pathway 

(Ref. 1, Section 3.1.2.1, Table 3-2). 

TABLE 4: Containment Factors for Source No. 1

Containment Description

Containment 

Factor Value References

Gas release to air NS NA

Particulate release to air NS NA

Release to ground water: No liner 10 1, Section 3.1.2.1, Table 3-2; 12, 

pp. 56, 57, 59, 73, 75, 76, 77; 20, 

pp. 125, 126, 129

Release via overland migration and/or flood NS NA

Notes: 

NA Not applicable 

No. Number 

NS Not scored
2.4.2.1 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

Information on the measure (in pounds) of individual hazardous substances in Source No. 1 is not 

available to evaluate Tier A, hazardous constituent quantity. The number of samples collected is not 

statistically representative of the range of concentrations throughout the source. Therefore, it is not 

possible to adequately determine a hazardous constituent quantity for Source No. 1 with reasonable 

confidence (Ref. 1, Section 2.4.2.1.1). Scoring proceeds to the evaluation of Tier B, hazardous 

wastestream quantity (Ref. 1, Section 2.4.2.1.2). 

 Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information on the total mass of all hazardous wastestreams and CERCLA pollutants and 

contaminants for Source No. 1 is not sufficient to evaluate Tier B, hazardous wastestream quantity. There 

is insufficient information that documents wastestream disposal; therefore, it is not possible to adequately 

determine a reasonably complete hazardous wastestream quantity for Source No. 1 (Ref. 1, Section 

2.4.2.1.2). Scoring proceeds to the evaluation of Tier C, volume (Ref. 1, Section 2.4.2.1.3). 

 

Hazardous Wastestream Quantity Assigned Value: NS

2.4.2.1.3 Volume

The depth of the contaminated soil source is not known and the extent of the source has not been 

determined. The information available is not sufficient to evaluate Tier C, volume, as required by 

Reference 1, Table 2-5. 

 Volume Assigned Value: 0 

2.4.2.1.4 Area

Source No. 1 contains multiple discrete areas of contaminated soil where illegal discharges and spills 

occurred; however, the extent and continuity of contamination between discrete areas in Source No. 1 is 

not known. Therefore, the area of Source No. 1 is undetermined, but greater than zero (see Figure 3 and 

Tables 2 and 3 of this HRS documentation record). 

 Sum (ft2

): >0 

Equation for Assigning Value (Table 2-5): Area (A)/34,000 

Area Assigned Value: >0 

2.4.2.1.5 Source Hazardous Waste Quantity Value

The source hazardous waste quantity (HWQ) value for Source No. 1 is assigned a source HWQ value of 

greater than zero, but undetermined (Ref. 1, Section 2.4.2.1.5). 

Source HWQ Value: >0

25 Source Characterization 
26 Source Characterization 

2.2.1 SOURCE IDENTIFICATION

Number of source: 2 

Name of source: Oil/Water Separator 

Source Type: Tank 

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

Source No. 2 is an oil/water separator (underground tank) located about 35 feet south of the 

manufacturing building (Refs. 11, p. 132; 12, p. 3) (see Figure 2 of this HRS documentation record). The 

oil/water separator was used by Walker Machine and received solvent waste (Refs. 12, p. 133; 19, p. 4; 

40). The oil/water separator is a concrete structure that contains a metal lid; however, it is not known if 

the bottom of the structure is concrete (Ref. 40). Specific information regarding the dimensions, capacity, 

how long Walker Machine used the oil/water separator, and the specific applications of the oil/water 

separator are not known (Ref. 40). According the current owner of the property, Langley has not used the 

oil/water separator (Refs. 8, p. 4; 12, p. 4; 40). 

In July 2007, TDEC collected a waste sample from the oil/water separator (Ref. 11, pp. 6, 7, 113, 114; 

40). The sample contained vinyl chloride (35 μg/L) and cis-1,2-DCE (14 μg/L) (Ref. 11, pp. 113, 114). 
27 Source Characterization 

2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

July 2007 

The liquid sample listed in Table 5 was collected by TDEC. Liquid source sample WM-WA-01 was 

collected from the oil/water separator located about 35 feet south of the manufacturing building (Refs. 11, 

pp. 6, 7, 113, 114, 132; 12, p. 3) (see Figure 2 of this HRS documentation record). The source sample 

was collected in accordance with the EPA Region 4 SESD Field Branches Quality System and Technical 

Procedures for Waste Sampling, SESDPROC-302-R0, February 2007 (Refs. 40; 63). The sample was

analyzed for VOCs (EPA Method 5035/5030B/8260B) by the State of Tennessee Environmental 

Laboratories, Jackson Regional Laboratory (Ref. 11, pp. 112, 113, 114). The method detection limits are 

listed on the analytical data sheets in Reference 11, Appendix C. The method detection limit is the 

minimum concentration of an analyte that can be identified, measured, and reported with a 99 percent 

confidence that the analyte concentration is greater than zero (Ref. 73, p. 1). The chain-of-custody form 

is provided in Reference 40. The location of the Source No. 2 sample listed in Table 5 is provided in 

Reference 12, p. 3. 

TABLE 5: Analytical Results for Source No. 2 – July 2007

Sample ID

Hazardous

Substance

Hazardous

Substance 

Concentration MDL References

WM-WA-01 cis-1,2-DCE 14 μg/L 5.0 μg/L 11, p. 113; 40

WM-WA-01 Vinyl chloride 35 μg/L 5.0 μg/L 11, p. 114; 40

Notes: 

DCE Dichloroethylene 

ID Identification 

μg/L Micrograms per liter 

MDL Method detection limit (Ref. 73, p. 1) 

No. Number 

WA Waste 

WM Walker Machine Products, Inc. 
28 Source Characterization 

2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

The sample collected from Source No. 2 contained cis-1,2-DCE and vinyl chloride (see Table 5 of this 

HRS documentation record). Source No. 2 is an oil/water separator located about 35 feet south of the 

manufacturing building (Refs. 11, p. 132; 12, p. 3). A liner was not observed in the vicinity of Source 

No. 2 during sampling activities for the 2011 SI and the 2012 ESI (Refs. 12, pp. 56, 57, 59, 73, 75, 76, 77; 

20, pp. 125, 126, 129). Therefore, a containment factor value of 10, as noted in Table 6, was assigned for 

the ground water migration pathway (Ref. 1, Section 3.1.2.1, Table 3-2). 

TABLE 6: Containment Factors for Source No. 2

Containment Description

Containment 

Factor Value References

Gas release to air NS NA

Particulate release to air NS NA

Release to ground water: No liner 10 1, Section 3.1.2.1, Table 3-2; 12, 

pp. 56, 57, 59, 73, 75, 76, 77; 20, 

pp. 125, 126, 129

Release via overland migration and/or flood NS NA

Notes: 

NA Not applicable 

No. Number 

NS Not scored
29 Source Characterization 

2.4.2.1 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

Information on the measure (in pounds) of individual hazardous substances in Source No. 2 is not 

available to evaluate Tier A, hazardous constituent quantity. The number of samples collected is not 

statistically representative of the range of concentrations throughout the source. Therefore, it is not 

possible to adequately determine a hazardous constituent quantity for Source No. 2 with reasonable 

confidence (Ref. 1, Section 2.4.2.1.1). Scoring proceeds to the evaluation of Tier B, hazardous 

wastestream quantity (Ref. 1, Section 2.4.2.1.2). 

 Hazardous Constituent Quantity Assigned Value: NS 

2.4.2.1.2 Hazardous Wastestream Quantity

The information on the total mass of all hazardous wastestreams and CERCLA pollutants and 

contaminants for Source No. 2 is not sufficient to evaluate Tier B, hazardous wastestream quantity. There 

is insufficient information that documents wastestream disposal; therefore, it is not possible to adequately 

determine a reasonably complete hazardous wastestream quantity for Source No. 2 (Ref. 1, Section 

2.4.2.1.2). Scoring proceeds to the evaluation of Tier C, volume (Ref. 1, Section 2.4.2.1.3). 

 Hazardous Wastestream Quantity Assigned Value: NS 

2.4.2.1.3 Volume

The oil/water separator is a concrete structure with a metal lid. It is not known if the bottom of the 

structure is concrete (Ref. 40). Specific information regarding the dimensions and capacity of the 

oil/water separator is not known (Ref. 40). Therefore, the volume of Source No. 2 is undetermined but 

greater than zero. 

Sum: >0 ft3 

 Equation for Assigning Value (Ref. 1, Table 2-5): Volume/2.5 

 Volume Assigned Value: >0 

2.4.2.1.4 Area

Area is not evaluated for source type tank (Ref. 1, Section 2.4.2.1.4, Table 2-5). 

Area Assigned Value: 0 

2.4.2.1.5 Source Hazardous Waste Quantity Value

The source HWQ value for Source No. 2 is assigned a source HWQ value of greater than zero, but 

undetermined (Ref. 1, Section 2.4.2.1.5). 

Source HWQ Value: >0 
30 Source Characterization 

SUMMARY OF SOURCE DESCRIPTIONS

TABLE 7: Summary of Source Descriptions

Source 

No.

Source

Hazardous

Waste

Quantity

Value

Source 

Hazardous

Constituent 

Quantity

Complete?

(Yes/No)

Containment Factor Value by Pathway

Ground 

Water

(Ref. 1, 

Table 3-2)

Surface 

Water

Overland/ 

Flood

(Ref. 1, 

Table 4-2)

Air

Gas

(Ref. 1, 

Table 6-3)

Particulate

(Ref. 1, 

Table 6-9)

1 >0 No 10 NS NS NS

2 >0 No 10 NS NS NS

Notes: 

 

 > Greater than 

No. Number 

NS Not scored 

Ref. Reference

Description of Other Possible On-Site Sources

No other possible current on-site sources have been identified. 

 
31 GW-Likelihood of Release 

3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 GENERAL CONSIDERATIONS

Ground Water Migration Pathway Description

Regional Geology: 

Walker Machine is located in the southeastern portion of Shelby County, Tennessee, within the East Gulf 

Coastal Plain, near the axis of the Mississippi embayment structural trough (Refs. 44, p. 2; 45, pp. O3, 

O8). Surface topography in the Memphis area (which includes Collierville, Tennessee) ranges from about 

200 feet above sea level on the flat alluvial plain of the Mississippi River to about 400 feet above sea 

level in the upland hills of eastern Shelby County (Ref. 46, pp. 3, 4). The Memphis area includes 

Collierville, Tennessee (Refs. 45, p. O3; 46, p. 3; 48, p. 3; 50, p. 3; 52, p. 4). 

The Walker Machine property is located at about 350 feet above mean sea level (msl) (Ref. 3) (see Figure 

1 of this HRS documentation record). The geology in the Collierville area may include, in descending 

stratigraphic order, some or all of the following units: alluvium, loess, terrace deposits, the Jackson 

Formation and the upper part of the Claiborne Group, the Claiborne Group (Memphis Sand), and the 

Wilcox Group (the Flour Island Formation, the Fort Pillow Sand, and the Old Breastworks Formation) 

(Refs. 45, pp. O9 through O13; 46, p. 8). The Memphis Sand is also referred to as the 500-foot sand 

(Refs. 45, p. O10; 46, p. 8; 49, p. 4). 

The alluvium of Holocene and Pleistocene age ranges from a few feet to about 175 feet in thickness and is 

composed of sand, clay, silt, and gravel (Ref. 46, p. 8). The loess of Pleistocene age consists of silt, silty 

clay, and minor amounts of sand. The thickness of the loess ranges from 0 to 65 feet (Ref. 46, p. 8). The 

terrace deposits of Pleistocene and Pliocene age range from a few feet to about 160 feet in thickness and 

are lithologically similar to the overlying alluvium. Terrace deposits are composed mostly of coarsegrained quartz sand and fine–grained, iron-stained quartz and chert gravel. Thin lenses of silty, ochercolored clay are common in the lower part of the terrace deposits (Ref. 45, pp. O10, O12, O13). The 

terrace deposits occur as an irregular belt parallel to the Mississippi River and occur along larger streams. 

The deposits thin gradually eastward and are absent in many places as a result of erosion or nondeposition 

(Ref. 45, p. O12).

Underlying the terrace deposits is the Jackson Formation and the upper part of the Claiborne Group 

(Cockfield and Cook Mountain Formations) (Refs. 46, p. 8; 50, pp. 6, 18). These Formations compose 

the Jackson-upper Claiborne confining unit (Ref. 50, pp. 7, 18). Because of their lithologic similarities, 

the Jackson Formation and the upper part of the Claiborne Group cannot be reliably subdivided in the 

subsurface of the Memphis area; however, some generalizations can be made concerning these units (Ref. 

50, p. 7). 

The Jackson Formation occurs only beneath the higher hills and ridges in the northern part of the 

Memphis area, consists of fine sand or sandy clay, and ranges from 0 to about 50 feet in thickness. The 

Jackson Formation overlies the Cockfield Formation, which consists of interfingering fine sand, silt, clay, 

and local lenses of lignite, and ranges from 0 to about 250 feet in thickness (Ref. 50, p. 7). The Cook 

Mountain Formation underlies the Cockfield Formation, consists primarily of clay and varying amounts 

of fine sand, and ranges from about 30 to 150 feet in thickness (Ref. 50, p. 9). The Jackson-upper 

Claiborne confining unit is absent in the Collierville area (Refs. 50, p. 9, Plates 1 and 4). 

Where present, the Jackson-upper Claiborne confining unit overlies the Memphis Sand and consists of a 

thick body of sand with subordinate lenses or beds of clay and silt at various horizons (Refs. 46, p. 8; 49, 

p. 5). The clay and silt are carbonaceous and lignitic (Ref. 49, p. 5). 

The Memphis Sand ranges from very fine to very coarse, but is locally fine, fine to medium, or medium to 

coarse (Ref. 49, p. 5). The Memphis Sand ranges from about 500 to 890 feet in thickness and is 
32 GW-Likelihood of Release 

encountered between 350 feet above msl and 325 feet below msl in Collierville, Tennessee (Refs. 46, p. 

8; 47, Plates 3 and 4). Collierville is located in the outcrop area of the Memphis Sand (Refs. 47, Plate 4; 

49, p. 6). 

The Wilcox Group underlies the Memphis Sand and is divided into the Flour Island Formation (confining 

unit), the Fort Pillow Sand (aquifer), and the Old Breastworks Formation (confining unit) (Ref. 46, p. 8). 

The Flour Island Formation consists of silty clays and sandy silts with lenses and interbeds of fine sand 

and lignite (Ref. 46, p. 8). The confining unit is about 280 feet thick in the Collierville area (Ref. 46, p. 

21). The base of the Memphis Sand is encountered at 325 feet below msl (Ref. 47, Plate 3). Therefore, 

the Flour Island Formation is encountered from about 325 feet below msl to 605 feet below msl (Refs. 46, 

p. 21; 47, Plate 3). 

The Fort Pillow Sand underlies the Flour Island Formation, is composed of sand with minor amounts of 

clay and lignite, and is about 100 feet thick in the Collierville area (Ref. 46, pp. 8, 20). The Old 

Breastworks Formation consists primarily of silty clays and clayey silts with lenses and interbeds of fine 

sand and lignite. The Old Breastworks Formation serves as the lower confining unit for the Fort Pillow 

Sand and ranges between 180 and 350 feet in thickness (Ref. 46, p. 8). 

Regional Aquifer Description:

Ground water in the Collierville area occurs, in descending order, in all or some of the following aquifers: 

(1) shallow water table, (2) the Memphis Sand (500-foot sand), and (3) the Fort Pillow Sand (1,400-foot 

sand) (Ref. 48, pp. 3, 5). The alluvium and terrace deposits make up the shallow water-table aquifer 

(surficial aquifer) (Ref. 46, p. 8). The shallow water-table aquifer is separated from the underlying 

Memphis Sand aquifer by the Jackson-upper Claiborne confining unit, where present (Ref. 46, p. 8). The 

Memphis Sand and Fort Pillow Sand aquifers are separated by the Flour Island Formation confining unit 

(Ref. 46, p. 8). The Memphis Sand is the principal source of water for public and industrial supplies in 

western Tennessee (Ref. 53, p. 2). The Memphis Sand aquifer is also referred to as the Memphis aquifer 

in regional geology references, but the term Memphis Sand aquifer is used throughout this HRS 

documentation record (Refs. 46, p. 8; 48, p. 5; 52, p. 5; 53, p. 2). 

The water table aquifer is unconfined and is composed of alluvium and terrace deposits of Holocene, 

Pleistocene, and Pliocene ages (Refs. 46, p. 8; 48, p. 6; 52, p. 5). Alluvium occurs at land surface in 

stream valleys and consists of gravel, sand, silt, and clay (Ref. 46, p. 6). Rivers dominate the hydrology 

of the water table aquifer (Ref. 48, p. 6). Local streams are in direct hydraulic connection with the water 

table aquifer and function as a drain during much of the year (Ref. 48, p. 6). Recharge to the water table 

aquifer is mainly from the infiltration of rainfall (Ref. 48, p. 8). 

The Jackson-upper Claiborne confining bed, where present, separates the water table and Memphis Sand 

aquifers. The confining bed is composed of clay, silt, fine sand, and lignite (Ref. 48, pp. 5, 6, 9). The 

confining bed is absent underlying and within 2 miles of Walker Machine (Refs. 46, pp. 8, 12; 50, Plate 1; 

51). 

The Memphis Sand aquifer is composed of a thick body of fine to very coarse sand with subordinate 

lenses of clay and silt at various stratigraphic horizons (Ref. 48, p. 8). The aquifer ranges from 500 to 890 

feet in thickness and is about 600 feet thick in the Collierville area (Ref. 46, pp. 8, 14). 

The Memphis Sand aquifer outcrops along a broad belt trending northeastward across western Tennessee 

and includes Collierville, Tennessee (Refs. 48, p. 8; 52, pp. 8, 9; 53, p. 2). In this outcrop area, the 

Jackson-upper Claiborne confining bed is not continuous or is not present (Refs. 46, pp. 8, 12; 50, Plate 1; 

51). Therefore, the Memphis Sand aquifer is unconfined and under water table conditions in the 

Collierville area. In the outcrop-recharge belt, the configuration of the Memphis Sand potentiometric 

surface is complex. Except at seeps and springs, the water table is lower than land surface, but generally 

conforms to the topography (Ref. 53, p. 2). In the Collierville area, ground water flows westward, down 
33 GW-Likelihood of Release 

the dip of the aquifer and also toward the major streams that drain the area (Refs. 48, p. 8; 53, pp. 2, Plate 

1). 

The Flour Island Formation separates the Memphis Sand and Fort Pillow Sand aquifers and is composed 

primarily of silty clay and sandy silt with lenses and interbeds of fine sand and lignite that are not areally 

extensive (Refs. 46, p. 8; 48, p. 9). The formation is about 280 feet thick in the Collierville area (Ref. 46, 

p. 21). 

The Fort Pillow Sand aquifer consists of fine- to medium-grained sand containing clay lenses and minor 

amounts of lignite. The aquifer is about 100 feet thick in the Collierville area (Ref. 46, pp. 15, 20). 

Shelby County is second in the nation in regard to sole dependence on ground water for municipal use 

(Ref. 69, p. 7). Ground water withdrawals in Shelby County account for nearly 80 percent of the water 

for the state of Tennessee. These ground water withdrawals have caused major cones of depression and 

reorientation of aquifer gradients within the county as well as within adjacent counties (Ref. 69, p. 8). 

The widespread and irregular distribution of pumping centers in the Memphis Sand aquifer in the 

Memphis area causes a complex flow pattern as ground water flows inward from all directions to several 

pumping centers (Ref. 46, pp. 15, 16). The predevelopment gradient of the Memphis Sand aquifer 

underlying Shelby County was to the west-northwest (Ref. 69, p. 8). In the Collierville area, ground 

water flow within the Memphis Sand aquifer is west-northwest towards the Memphis Light, Gas, and 

Water Division Sheahan wellfield (Refs. 46, p. 14; 69, p. 72). 

Water levels in the Memphis Sand aquifer fluctuate seasonally as a result of increases or decreases in 

pumping of the aquifer (Ref. 50, p. 24). Generally, pumping from the Memphis Sand aquifer is less in the 

winter and spring, and water levels rise (Ref. 50, pp. 24, 27). Beginning in early summer, the demand for 

water increases and pumping increases. Pumping continues to increase through the summer, and water 

levels in the aquifer continue to decline (Ref. 50, p. 27). 

Site Geology/Hydrogeology: 

Well logs for Town of Collierville’s municipal well Nos. 102 and 103 (located about 0.51 mile west of 

Walker Machine) indicate that the Collierville area is underlain by sand, sandy clay, and clay (Refs. 3; 70, 

pp. 2 through 5). The stratigraphy encountered during drilling activities from land surface to the depth of 

each municipal well (Well No. 102 – 635 feet bgs and Well No. 103 – approximately 273 feet bgs) is 

discussed below (Ref. 70, pp. 2 through 5). 

Municipal well No. 102 indicates that the area is underlain by clay (0 to 20 feet bgs), sandy clay (20 to 36 

feet bgs), sand rock and sand with white streaks of clay (36 to 102 feet bgs), fine to medium sand with 

clay streaks (102 to 297 feet bgs), clay and clay with sandy streaks (297 to 363 feet bgs), clay (363 to 368 

feet bgs), and fine and medium firm sand with clay streaks and sandy clay (368 to 647 feet bgs) (Ref. 70, 

p. 3). The well is installed in the unconfined Memphis Sand aquifer at a depth of 635 feet bgs and is 

screened between 529 and 635 feet bgs (Refs. 67, p. 1; 70, p. 2). 

Municipal well No. 103 is underlain by 20 feet of brown clay and red sand (0 to 20 feet bgs), 10 feet of 

white clay (20 to 30 feet bgs), 50 feet of white sand (30 to 80 feet bgs), 60 feet of brown medium sand (80 

to 140 feet bgs), 73 feet of white sand (140 to 213 feet bgs), 4 feet of white clay (213 to 217 feet bgs), 73 

feet of coarse white sand (217 to 290 feet bgs), 3.5 feet of rock (290 to 293.5 feet bgs), 6.5 feet of white 

clay (293.5 to 300 feet bgs), 29 feet of gray sand (300 to 329 feet bgs), 66 feet of white sand (329 to 395 

feet bgs), 5 feet of white sand with white clay streaks (395 to 400 feet bgs), 20 feet of white sand (400 to 

420 feet bgs), and 20 feet of white sand with white clay streaks (420 to 440 feet bgs) (Ref. 70, p. 5). The 

well is installed in the unconfined Memphis Sand aquifer and is screened between 192.75 feet bgs and 

273 feet bgs (Refs. 67, p. 1; 70, pp. 4, 5). However, the boring was advanced and logged down to 440 

feet bgs (Ref. 70, pp. 4, 5). 

 
34 GW-Likelihood of Release 

The deepest boring advanced at Walker Machine was to a depth of 83 feet bgs while installing monitoring 

well MW-5 during the 2010 reassessment (Ref. 19, pp. 1, 106, 107). Therefore, verified geology 

underlying Source Nos. 1 and 2 at Walker Machine is limited to this depth. 

The 83-foot boring at the location of well MW-5 indicated that Walker Machine is underlain by 15 feet of 

clay-like silt, followed by 13 feet of sandy clay with small lenses of sand. Sand dominates from 28 feet 

bgs (346.11 feet above msl) to the completion of the boring at 83 feet bgs (263.11 feet above msl) (Ref. 

19, pp. 106, 107). During installation of the monitoring well, water was encountered at 59 feet bgs, 

indicating the top of the Memphis Sand aquifer (about 286.84 feet above msl) (Refs. 19, pp. 106, 107; 

51). The top of the Memphis Sand aquifer identified at the Walker Machine property (about 286.84 feet 

above msl) correlates with regional geology references. In regional geology references, the top of the 

Memphis Sand aquifer is encountered at about 280 feet above msl (Refs. 47, Plate 5; 49, p. 8). 

The permanent monitoring wells installed at the Walker Machine and Witt International properties were 

gauged in March 2009, February 2010, April 2011, and June 2012 (Refs. 12, p. 62; 19, p. 111; 20, p. 73; 

22, pp. 28, 30, 32, 34, 39). Subsequent potentiometric mapping revealed that, locally, ground water was 

flowing northeast in March 2009; radially from monitoring well WI-MW-01 and north from monitoring 

well WM-MW-04 in February 2010 and April 2011; and radially from monitoring well WI-MW-01 in 

June 2012 (Refs. 12, p. 62; 19, p. 111; 20, p. 73; 71). 

Even though potentiometric mapping of the ground water underlying the Walker Machine property 

revealed varying directions of ground water flow during the March 2009, February 2010, April 2011, and 

June 2012 sampling events, the regional ground water flow direction in the Collierville area is towards the 

west (Refs. 12, p. 62; 19, p. 111; 20, p. 73; 69, p. 72; 71). 

The determination of ground water flow on the Walker Machine property is limited to the wells installed 

on the Walker Machine property and neighboring Witt International property and the dates on which the 

permanent monitoring wells were gauged. Therefore, the potentiometric maps generated from these 

gauging events only provide a snapshot of localized ground water flow within the site-specific monitoring 

well network on the dates gauged (March 2009, February 2010, April 2011, and June 2012) (Ref. 71). 

The variability in ground water flow direction observed on the Walker Machine property is based on 

limited site specific data and may be attributed to seasonal variations. Locations, such as the Walker 

Machine property, that exhibit low potentiometric gradients are more susceptible to variable ground water 

flow directions than areas with high potentiometric gradients (Ref. 71). The permanent monitoring wells 

located on the Walker Machine property and neighboring Witt International property were gauged during 

the months of March, February, April, and June. The Collierville area experiences greater rainfall during 

this time period. Gauging the permanent monitoring wells during the late summer and early fall months 

might reveal a different directional ground water flow (Ref. 71). 

Aquifer Interconnectivity and Discontinuity: 

Collierville, Tennessee is in the outcrop area of the Memphis Sand aquifer. In this outcrop area, the 

aquifer is unconfined and under water table conditions (Refs. 48, p. 8; 51; 52, pp. 8, 9; 53, p. 2; 67, p. 1). 

The Jackson-upper Claiborne confining bed is not present at or within 2 miles of Source Nos. 1 and 2 

(Refs. 3; 46, p. 12; 48, pp. 5, 6; 50, Plate 1; 51; 60, p. 1; 67, p. 9). 

The Memphis Sand aquifer is the principal source of water for public and industrial supplies in western 

Tennessee. The aquifer is continuous within a 4-mile radius of sources at Walker Machine (Ref. 53, pp. 

1, 3). 
35 GW-Likelihood of Release 

SUMMARY OF AQUIFERS BEING EVALUATED

TABLE 8: Summary of Aquifers Being Evaluated

Aquifer Name

Is Aquifer 

Interconnected with 

Upper Aquifer within 2 

Miles? (Yes/No/NA)

Is Aquifer 

Continuous within 

4-mile TDL? 

(Yes/No)

Is Aquifer 

Karst? 

(Yes/No) References

Memphis Sand NA Yes No

3; 46, p. 12; 48, pp. 

5, 6, 8; 50, Plate 1; 

51; 52, pp. 8, 9; 53, 

p. 2; 60, p. 1; 67, pp. 

1, 9

Notes: 

NA Not applicable 

TDL Target distance limit
36 GW-Likelihood of Release 

3.1 LIKELIHOOD OF RELEASE

3.1.1 OBSERVED RELEASE

Aquifer Being Evaluated: Memphis Sand Aquifer 

Chemical Analysis

April 2011

Background Samples 

The background samples listed in Table 9 were collected by TDEC during the April 2011 SI sampling 

event (Refs. 12, pp. 1, 8, 120; 41, p. 8). Potentiometric mapping of permanent monitoring wells installed 

at Walker Machine and Witt International indicated that ground water was flowing radially from 

monitoring well WI-MW-01 and north from monitoring well WM-MW-04 (Refs. 12, p. 62; 71). 

Permanent monitoring well WI-MW-01 is located southwest of Source Nos. 1 and 2 and permanent 

monitoring well WM-MW-04 is located south of Source Nos. 1 and 2. These locations are upgradient of 

ground water underlying and in the vicinity of Source Nos. 1 and 2 at the time of sampling (Refs. 12, p. 

62; 71) (see Figures 3 and 4 of this HRS documentation record). The background samples listed in Table 

9 were collected from the Memphis Sand aquifer and are used to represent background conditions for 

observed releases to the Memphis Sand aquifer underlying and in the vicinity of sources at Walker 

Machine (Refs. 12, pp. 8, 62; 51) (see Figures 3 and 4 of this HRS documentation record). 

Background and contaminated permanent monitoring wells are screened in the Memphis Sand aquifer at 

similar depths (Refs. 19, pp. 104 through 107; 40; 51; 54, pp. 3 through 6). Specifically the depths of the 

wells installed in the Memphis Sand aquifer listed in Tables 9 and 11 range from 66.7 to 80 feet bgs 

(Refs. 12, p. 8; 19, pp. 104 through 107; 40; 51; 54, pp. 3 through 6). The monitoring well construction 

diagrams for the background monitoring wells are provided in References 19 and 54. Based on the 

monitoring well construction diagrams for wells MW-MW-04 and WI-MW-01, the total well depth is 

equivalent to the bottom of the screen interval (Refs. 19, pp. 104, 105; 54, pp. 3, 4). 

Background and release ground water samples were collected during the same investigation, in 

accordance with the same sampling procedures, and from wells screened in the same aquifer (Refs. 12, p. 

8; 19, pp. 104 through 107; 40; 41, p. 8; 51; 54, pp. 3 through 6; 57). The background ground water 

samples were collected in accordance with the EPA Region 4 SESD Field Branches Quality System and 

Technical Procedures for Groundwater Sampling, SESDPROC-301-R1, November 2007 (Refs. 40; 57). 

The locations of the background ground water samples are depicted on page 9 in Reference 12. Logbook 

notes are contained in Reference 12, pages 66 through 78. Monitoring well logs are contained in 

References 19 and 54. The chain-of-custody records are contained in Reference 41. 

TABLE 9: Background Ground Water Samples – Memphis Sand Aquifer

Well Screened 

Monitoring Depth Interval Date 

Well ID Sample ID (feet bgs) (feet bgs) Sampled Location References

WM-MW-04 WM040411GW 66.7 46.7 to 66.7 4/26/2011

About 260 feet 

south of Source 

No. 2

12, pp. 3, 8, 9, 

71, 72, 73; 19, 

pp. 104, 105; 41, 

p. 8
37 GW-Likelihood of Release 

TABLE 9: Background Ground Water Samples – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Well 

Depth 

(feet bgs)

Screened 

Interval

(feet bgs)

Date 

Sampled Location References

WI-MW-01 WI010411GW 72 52 to 72 4/26/2011

About 220 feet 

southwest of 

Source No. 2, on 

the Witt 

International 

property

12, pp. 3, 8, 9, 

69, 70, 71; 41, p. 

8; 54, pp. 3, 4

Notes: 

bgs Below ground surface 

GW Ground water 

ID Identification number 

MW Monitoring well 

WI Witt International 

WM Walker Machine 
38 GW-Likelihood of Release 

Background Concentrations

The background ground water samples listed in Table 10 were collected from permanent monitoring wells 

installed in the Memphis Sand aquifer (Refs. 12, p. 8; 40; 51). The samples were analyzed for VOCs 

(EPA Method 8260C) by the EPA Region 4 ASB in accordance with the ASB LOQAM (Refs. 12, pp. 8, 

118, 120; 35). EPA Region 4 reviewed all data in accordance with the ASB LOQAM, EPA method and 

guidelines (Refs. 12, p. 118; 36). The MRLs are listed on the analytical data sheets in Reference 12, 

Appendix C. Each MRL is sample-specific and corresponds to the lowest quantitative point on the 

calibration curve; it is adjusted for the amount of sample prepared and any dilutions performed. The 

MRLs are equivalent to SQLs, as defined in HRS Section 1.1, Definitions (Refs. 1, Section 1.1; 37). 

Analytical data sheets are contained in Reference 12, Appendix C. 

TABLE 10: Analytical Results for April 2011 – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Hazardous 

Substance Concentration MRL References

WM-MW-04 WM040411GW PCE 330 μg/L 5.0 μg/L 12, pp. 8, 148

WM-MW-04 WM040411GW TCE 15 μg/L 5.0 μg/L 12, pp. 8, 148

WM-MW-04 WM040411GW 1,1-DCE 17 μg/L 5.0 μg/L 12, pp. 8, 146

WM-MW-04 WM040411GW cis-1,2-DCE 8.0 μg/L 5.0 μg/L 12, pp. 8, 147

WM-MW-04 WM040411GW 1,1,1-TCA 10 μg/L 5.0 μg/L 12, pp. 8, 146

WI-MW-01 WI010411GW PCE 400 μg/L 5.0 μg/L 12, pp. 8, 127

WI-MW-01 WI010411GW TCE 18 μg/L 5.0 μg/L 12, pp. 8, 127

WI-MW-01 WI010411GW 1,1-DCE 24 μg/L 5.0 μg/L 12, pp. 8, 125

WI-MW-01 WI010411GW cis-1,2-DCE 8.9 μg/L 5.0 μg/L 12, pp. 8, 126

WI-MW-01 WI010411GW 1,1,1-TCA 7.9 μg/L 5.0 μg/L 12, pp. 8, 125

Notes: 

DCE Dichloroethylene 

GW Ground water 

ID Identification number 

μg/L Micrograms per liter 

MRL Minimum reporting limit 

MW Monitoring well 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

WI Witt International 

WM Walker Machine
39 GW-Likelihood of Release 

Contaminated Samples 

Ground water samples listed in Table 11 were collected during the April 2011 TDEC SI from permanent 

monitoring wells completed in the Memphis Sand aquifer underlying and in the vicinity of Source Nos. 1 

and 2 (Refs. 12, pp. 1, 8, 9; 19, pp. 106, 107; 40; 41, p. 8; 51; 54, pp. 5, 6; 71) (see Figures 3 and 4 of this 

HRS documentation record). All ground water samples were collected in accordance with the EPA 

Region 4 SESD Field Branches Quality System and Technical Procedures for Groundwater Sampling, 

SESDPROC-301-R1, November 2007 (Refs. 40; 57). 

The contaminated ground water samples and their corresponding depths are provided in Table 11. 

Results for contaminated ground water samples underlying and in the vicinity of Source Nos. 1 and 2 

were compared with background ground water samples collected from monitoring wells WM-MW-04 and 

WI-MW-01, which are completed in the same aquifer at similar depths (Refs. 12, p. 8; 19, pp. 104 

through 107; 40; 51; 54, pp. 3 through 6) (see Tables 9 and 11 of this HRS documentation record).

The location of the contaminated ground water samples are depicted in Reference 12, page 9. Logbook 

notes are contained in Reference 12 pages 66 through 78. The monitoring well logs for WM-MW-05 and 

WI-MW-02 are contained in References 19 and 54. A monitoring well log is not available for well WMMW-03 (Ref. 40). Chain-of-custody records are contained in Reference 41. 

TABLE 11: Ground Water Samples – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Well 

Depth 

(feet 

bgs)

Screened 

Interval 

(feet bgs)

Date 

Sampled Location References

WM-MW-03 WM030411GW 80 60 to 80 4/26/2011 Adjacent to 

Source No. 2

12, pp. 3, 8, 9, 

70, 72, 73; 40; 

41, p. 8

WM-MW-03 WM00411GWD 80 60 to 80 4/26/2011 Adjacent to 

Source No. 2

12, pp. 3, 8, 9, 

70, 71, 73; 40; 

41, p. 8

WM-MW-05 WM050411GW 72 52 to 72 4/26/2011 Adjacent to 

Source No. 2

4; 8, p. 1; 11, p. 

2; 12, pp. 3, 8, 9, 

70, 73; 19, pp. 

106, 107; 41, p. 8

WI-MW-02 WI020411GW 79 59 to 79 4/26/2011

About 215 feet 

northwest of 

Source No. 2, on 

the Witt 

International 

property

12, pp. 3, 8, 9,

70, 71; 54, pp. 5, 

6; 41, p. 8

Notes: 

bgs Below ground surface 

D Duplicate sample 

GW Ground water 

ID Identification 

MW Monitoring well 

WI Witt International 

WM Walker Machine 
40 GW-Likelihood of Release 

Contaminated Concentrations 

Ground water samples listed in Table 12 were collected from permanent monitoring wells completed in 

the Memphis Sand aquifer (Refs. 12, p. 8; 40; 51). The samples were analyzed for VOCs (EPA Method 

8260C) by the EPA Region 4 SESD ASB in accordance with the ASB LOQAM (Refs. 12, pp. 8, 118, 

120; 35). EPA Region 4 SESD reviewed all data in accordance with the ASB LOQAM, EPA method and 

guidelines (Refs. 12, p. 118; 36). The MRLs are listed on the analytical data sheets in Reference 12, 

Appendix C. Each MRL is sample-specific and corresponds to the lowest quantitative point on the 

calibration curve; it is adjusted for the amount of sample prepared and any dilutions performed. The 

MRLs are equivalent to SQLs, as defined in HRS Section 1.1, Definitions (Refs. 1, Section 1.1; 37). 

Analytical data sheets are contained in Reference 12, Appendix C. 

TABLE 12: Analytical Results for April 2011 – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Hazardous 

Substance Concentration MRL References

WM-MW-03 WM030411GW PCE 1,400 μg/L 12 μg/L 12, pp. 8, 142

WM-MW-03 WM030411GW TCE 110 μg/L 12 μg/L 12, pp. 8, 142

WM-MW-03 WM030411GW 1,1-DCE 210 μg/L 12 μg/L 12, pp. 8, 140

WM-MW-03 WM030411GW cis-1,2-DCE 110 μg/L 12 μg/L 12, pp. 8, 141

WM-MW-03 WM030411GW 1,1,1-TCA 72 μg/L 12 μg/L 12, pp. 8, 140

WM-MW-03 WM030411GWD PCE 1,300 μg/L 12 μg/L 12, pp. 8, 145

WM-MW-03 WM030411GWD TCE 110 μg/L 12 μg/L 12, pp. 8, 145

WM-MW-03 WM030411GWD 1,1-DCE 190 μg/L 12 μg/L 12, pp. 8, 143

WM-MW-03 WM030411GWD cis-1,2-DCE 110 μg/L 12 μg/L 12, pp. 8, 144

WM-MW-03 WM030411GWD 1,1,1-TCA 67 μg/L 12 μg/L 12, pp. 8, 143

WM-MW-05 WM050411GW PCE 1,500 μg/L 12 μg/L 12, pp. 8, 151

WM-MW-05 WM050411GW TCE 120 μg/L 12 μg/L 12, pp. 8, 151

WM-MW-05 WM050411GW 1,1-DCE 180 μg/L 12 μg/L 12, pp. 8, 149

WM-MW-05 WM050411GW cis-1,2-DCE 120 μg/L 12 μg/L 12, pp. 8, 150

WM-MW-05 WM050411GW 1,1,1-TCA 66 μg/L 12 μg/L 12, pp. 8, 149

WI-MW-02 WI020411GW TCE 73 μg/L 10 μg/L 12, pp. 8, 130

WI-MW-02 WI020411GW 1,1-DCE 380 μg/L 10 μg/L 12, pp. 8, 128

WI-MW-02 WI020411GW cis-1,2-DCE 51 μg/L 10 μg/L 12, pp. 8, 129

WI-MW-02 WI020411GW 1,1,1-TCA 77 μg/L 10 μg/L 12, pp. 8, 128

Notes: 

D Duplicate sample 

DCE Dichloroethylene 

GW Ground water 

ID Identification number 

μg/L Micrograms per liter 

MRL Minimum reporting limit 

MW Monitoring well 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

WI Witt International 

WM Walker Machine
41 GW-Likelihood of Release 

June 2012

Background Samples 

The background samples listed in Table 13 were collected by TDEC during the June 2012 ESI sampling 

event (Refs. 8, pp. 1, 9; 21, p. 4; 41, pp. 4, 5). Potentiometric mapping of permanent monitoring wells 

installed at Walker Machine and Witt International indicated that ground water was flowing radially from 

permanent monitoring well WI-MW-01 at the time of sampling (Ref. 20, p. 73). In an effort to delineate 

releases from Source Nos. 1 and 2, several permanent monitoring wells surrounding the sources were 

selected to represent background conditions. Samples collected from permanent monitoring wells WMMW-01, WM-MW-02, WM-MW-04, and WI-MW-01 (installed in the Memphis Sand aquifer) are being 

used to represent background conditions for observed releases to the Memphis Sand aquifer underlying 

and in the vicinity of sources at Walker Machine (Refs. 8, p. 9; 20, p. 73; 40; 51) (see Figures 3 and 4 of 

this HRS documentation record). 

Both background and contaminated permanent monitoring wells are screened in the Memphis Sand 

aquifer at similar depths (Refs. 19, pp. 104 through 107; 40; 51; 54, pp. 3 through 6). Specifically, the 

depths of the wells installed in the Memphis Sand aquifer listed in Tables 13 and 15 range from 66.7 to 80 

feet bgs (Refs. 8, p. 9; 19, pp. 104 through 107; 40; 51; 54, pp. 3 through 6). The monitoring well 

construction diagrams for the background permanent monitoring wells are provided in References 19 and 

54. Based on the monitoring well construction diagrams for the background wells, the total well depth is 

equivalent to the bottom of the screen interval (Refs. 19, pp. 104, 105; 40; 54, pp. 3, 4). 

Background and release ground water samples were collected during the same investigation, in 

accordance with the same sampling procedures, and from wells screened in the same aquifer (Refs. 8, p. 

9; 19, pp. 104 through 107; 40; 41, pp. 4, 5; 51; 54, pp. 3 through 6; 58). The background ground water 

samples were collected in accordance with the EPA Region 4 SESD Field Branches Quality System and 

Technical Procedures for Groundwater Sampling, SESDPROC-301-R2, October 2011 (Refs. 40; 58). 

The locations of the background ground water samples are depicted on page 10 of Reference 8. Logbook 

notes and field sheets are contained in Reference 20, pages 112 through 143. Monitoring well logs for 

WM-MW-04 and WI-MW-01 are provided in References 19 and 54. Monitoring well logs for WM-MW01 and WM-MW-02 are not available (Ref. 40). The chain-of-custody records are contained in Reference 

41. 

TABLE 13: Background Ground Water Samples – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Well 

Depth 

(feet bgs)

Screened 

Interval

(feet bgs)

Date 

Sampled Location References

WM-MW-01 WM01-0612-GW 80 60 to 80 6/26/2012

About 330 feet 

east of Source 

No. 2

8, p. 9; 12, p. 3; 

20, pp. 73, 129, 

135; 40; 41, p. 

4; 

WM-MW-02 WM02-0612-GW 80 60 to 80 6/26/2012

About 200 feet 

northeast of 

Source No. 2

8, p. 9; 12, p. 3; 

20, pp. 73, 129, 

136; 40; 41, p. 4

WM-MW-04 WM04-0612-GW 66.7 46.7 to 

66.7 6/26/2012

About 260 feet 

south of Source 

No. 2

8, p. 9; 12, p. 3; 

19, pp. 104, 

105; 20, pp. 73, 

130, 138; 41, p. 

4
42 GW-Likelihood of Release 

TABLE 13: Background Ground Water Samples – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Well 

Depth 

(feet bgs)

Screened 

Interval

(feet bgs)

Date 

Sampled Location References

WI-MW-01 WI01-0612-GW 72 52 to 72 6/27/2012

220 feet 

southwest of 

Source No. 2, on 

the Witt 

International 

property

8, p. 9; 12, p. 3; 

20, pp. 73, 131, 

140; 54, pp. 3, 

4; 41, p. 5

Notes: 

bgs Below ground surface 

GW Ground water 

ID Identification number 

MW Monitoring well 

WI Witt International 

WM Walker Machine 
43 GW-Likelihood of Release 

Background Concentrations

The background ground water samples listed in Table 14 were collected from permanent monitoring wells 

installed in the Memphis Sand aquifer (Refs. 8, p. 9; 40; 51). The samples were analyzed for VOCs in 

accordance with the EPA CLP SOW SOM01.2 (Refs. 21, pp. 1, 2, 4; 42). EPA Region 4 reviewed all 

data according to the contract SOW and EPA guidelines (Refs. 21, p. 2; 36). The MRLs are listed on the 

analytical data sheets in Reference 21. Each MRL is sample-specific and corresponds to the lowest 

quantitative point on the calibration curve; it is adjusted for the amount of sample prepared and any 

dilutions performed. The MRLs are equivalent to SQLs, as defined in HRS Section 1.1, Definitions 

(Refs. 1, Section 1.1; 37). Analytical data sheets are contained in Reference 21. 

TABLE 14: Analytical Results for June 2012 – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Hazardous 

Substance Concentration MRL References

WM-MW-01 WM01-0612-GW PCE 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 33

WM-MW-01 WM01-0612-GW TCE 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 33

WM-MW-01 WM01-0612-GW 1,1-DCE 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 32

WM-MW-01 WM01-0612-GW cis-1,2-DCE 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 33

WM-MW-01 WM01-0612-GW 1,1-DCA 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 32

WM-MW-01 WM01-0612-GW 1,1,1-TCA 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 32

WM-MW-02 WM02-0612-GW PCE 4.2U μg/L 4.2 μg/L 8, p. 9; 21, pp. 3, 5, 

35

WM-MW-02 WM02-0612-GW 1,1-DCE 1.2 μg/L 0.50 μg/L 8, p. 9; 21, p. 34

WM-MW-02 WM02-0612-GW cis-1,2-DCE 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 35

WM-MW-02 WM02-0612-GW 1,1-DCA 0.50U μg/L 0.50 μg/L 8, p. 9; 21, p. 34

WM-MW-04 WM04-0612-GW PCE 220 μg/L 10 μg/L 8, p. 9; 21, p. 41

WM-MW-04 WM04-0612-GW TCE 11 μg/L 5.0 μg/L 8, p. 9; 21, p. 41

WM-MW-04 WM04-0612-GW 1,1-DCE 17 μg/L 5.0 μg/L 8, p. 9; 21, p. 40

WM-MW-04 WM04-0612-GW cis-1,2-DCE 6.8 μg/L 5.0 μg/L 8, p. 9; 21, p. 41

WM-MW-04 WM04-0612-GW 1,1,1-TCA 10 μg/L 5.0 μg/L 8, p. 9; 21, p. 40

WI-MW-01 WI01-0612-GW PCE 29U μg/L 29 μg/L 8, p. 9; 21, pp. 3, 5, 

25

WI-MW-01 WI01-0612-GW TCE 7.5 μg/L 5.0 μg/L 8, p. 9; 21, p. 25

WI-MW-01 WI01-0612-GW 1,1-DCE 18 μg/L 5.0 μg/L 8, p. 9; 21, p. 24

WI-MW-01 WI01-0612-GW cis-1,2-DCE 8.4 μg/L 5.0 μg/L 8, p. 9; 21, p. 25

WI-MW-01 WI01-0612-GW 1,1,1-TCA 5.6 μg/L 5.0 μg/L 8, p. 9; 21, p. 24

Notes: 

DCA Dichloroethane 

DCE Dichloroethylene 

GW Ground water 

ID Identification number 

μg/L Micrograms per liter 

MRL Minimum reporting limit 
44 GW-Likelihood of Release 

MW Monitoring well 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

U The analyte was not detected at or above the reporting limit (Ref. 21, p. 5). 

WI Witt International 

WM Walker Machine 
45 GW-Likelihood of Release 

Contaminated Samples 

Ground water samples listed in Table 15 were collected from permanent monitoring wells completed in 

the Memphis Sand aquifer underlying and in the vicinity of Source Nos. 1 and 2 during the June 2012 

TDEC ESI (Refs. 8, p. 1, 9; 19, pp. 106, 107; 40; 51; 54, pp. 5, 6) (see Figures 3 and 4 of this HRS 

documentation record). All ground water samples were collected in accordance with the EPA Region 4 

SESD Field Branches Quality System and Technical Procedures for Groundwater Sampling, 

SESDPROC-301-R2, October 2011 (Refs. 40; 58). 

The contaminated ground water samples and their corresponding depths are provided in Table 15. 

Results for contaminated ground water samples underlying and in the vicinity of Source Nos. 1 and 2 

were compared with background ground water samples completed in the same aquifer at similar depths 

(Refs. 8, p. 9; 19, pp. 104 through 107; 40; 51; 54, pp. 3 through 6) (see Tables 13 and 15 of this HRS 

documentation record). 

The locations of the contaminated ground water samples are depicted in Reference 20, page 73. Logbook 

notes and field sheets are contained in Reference 8, pages 112 through 143. Monitoring well logs for 

WM-MW-05 and WI-MW-02 are contained in References 19 and 54. A monitoring well log is not 

available for WM-MW-03 (Ref. 40). Chain-of-custody records are contained in Reference 41. 

TABLE 15: Ground Water Samples – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Well 

Depth 

(feet bgs)

Screened 

Interval 

(feet bgs)

Date 

Sampled Location References

WM-MW-03 WM03-0612-GW 80 60 to 80 6/27/2012 Adjacent to 

Source No. 2

8, p. 9; 12, p. 3; 

20, pp. 73, 131, 

137; 40; 41, p. 5

WM-MW-03 WM03-0612-GWD 80 60 to 80 6/27/2012 Adjacent to 

Source No. 2

8, p. 9; 12, p. 3; 

20, pp. 73, 131, 

137; 40; 41, p. 5

WM-MW-05 WM05-0612-GW 72 52 to 72 6/27/2012 Adjacent to 

Source No. 2

4; 8, p. 1, 9; 11, 

p. 2; 12, p. 3; 19, 

pp. 106, 107; 20, 

pp. 73, 131, 139; 

41, p. 5

WI-MW-02 WI02-0612-GW 79 59 to 79 6/27/2012

About 215 feet 

northwest of 

Source No. 2, 

on the Witt 

International 

property

8, p. 9; 12, p. 3; 

20, pp. 73, 131, 

141; 54, pp. 5, 6; 

41, p. 5

Notes: 

bgs Below ground surface 

D Duplicate sample 

GW Ground water 

ID Identification 

MW Monitoring well 

WI Witt International 

WM Walker Machine 
46 GW-Likelihood of Release 

Contaminated Concentrations 

Ground water samples listed in Table 16 were collected from permanent monitoring wells completed in 

the Memphis Sand aquifer (Ref. 8, p. 9; 40; 51). The samples were analyzed for VOCs in accordance 

with the EPA CLP SOW SOM01.2 (Refs. 21, pp. 1, 2, 4; 42). EPA Region 4 reviewed all data according 

to the contract SOW and EPA guidelines (Refs. 21, p. 2; 36). The MRLs are listed on the analytical data 

sheets in Reference 21. Each MRL is sample-specific and corresponds to the lowest quantitative point on 

the calibration curve; it is adjusted for the amount of sample prepared and any dilutions performed. The 

MRLs are equivalent to SQLs, as defined in HRS Section 1.1, Definitions (Refs. 1, Section 1.1; 37). 

Analytical data sheets are contained in Reference 21. 

TABLE 16: Analytical Results for June 2012 – Memphis Sand Aquifer

Monitoring 

Well ID Sample ID

Hazardous 

Substance Concentration MRL References

WM-MW-03 WM03-0612-GW PCE 1,700 μg/L 100 μg/L 8, p. 9; 21, p. 37

WM-MW-03 WM03-0612-GW TCE 130 μg/L 10 μg/L 8, p. 9; 21, p. 37

WM-MW-03 WM03-0612-GW 1,1-DCE 220 μg/L 10 μg/L 8, p. 9; 21, p. 36

WM-MW-03 WM03-0612-GW cis-1,2-DCE 130 μg/L 10 μg/L 8, p. 9; 21, p. 37

WM-MW-03 WM03-0612-GW 1,1-DCA 97 μg/L 10 μg/L 8, p. 9; 21, p. 36

WM-MW-03 WM03-0612-GW 1,1,1-TCA 72 μg/L 10 μg/L 8, p. 9; 21, p. 36

WM-MW-03 WM03-0612-GWD PCE 1,700 μg/L 100 μg/L 8, p. 9; 21, p. 39

WM-MW-03 WM03-0612-GWD TCE 130 μg/L 10 μg/L 8, p. 9; 21, p. 39

WM-MW-03 WM03-0612-GWD 1,1-DCE 210 μg/L 10 μg/L 8, p. 9; 21, p. 38

WM-MW-03 WM03-0612-GWD cis-1,2-DCE 130 μg/L 10 μg/L 8, p. 9; 21, p. 39

WM-MW-03 WM03-0612-GWD 1,1-DCA 96 μg/L 10 μg/L 8, p. 9; 21, p. 38

WM-MW-03 WM03-0612-GWD 1,1,1-TCA 69 μg/L 10 μg/L 8, p. 9; 21, p. 38

WM-MW-05 WM05-0612-GW PCE 2,000 μg/L 100 μg/L 8, p. 9; 21, p. 43

WM-MW-05 WM05-0612-GW TCE 150 μg/L 10 μg/L 8, p. 9; 21, p. 43

WM-MW-05 WM05-0612-GW 1,1-DCE 200 μg/L 10 μg/L 8, p. 9; 21, p. 42

WM-MW-05 WM05-0612-GW cis-1,2-DCE 160 μg/L 10 μg/L 8, p. 9; 21, p. 43

WM-MW-05 WM05-0612-GW 1,1-DCA 61 μg/L 10 μg/L 8, p. 9; 21, p. 42

WM-MW-05 WM05-0612-GW 1,1,1-TCA 67 μg/L 10 μg/L 8, p. 9; 21, p. 42

WI-MW-02 WI02-0612-GW TCE 50 μg/L 5.0 μg/L 8, p. 9; 21, p. 27

WI-MW-02 WI02-0612-GW 1,1-DCE 400 μg/L 20 μg/L 8, p. 9; 21, p. 26

WI-MW-02 WI02-0612-GW 1,1-DCA 73 μg/L 5.0 μg/L 8, p. 9; 21, p. 26

WI-MW-02 WI02-0612-GW 1,1,1-TCA 68 μg/L 5.0 μg/L 8, p. 9; 21, p. 26
47 GW-Likelihood of Release 

Notes: 

D Duplicate sample 

DCA Dichloroethane 

DCE Dichloroethylene 

GW Ground water 

ID Identification number 

μg/L Micrograms per liter 

MRL Minimum reporting limit 

MW Monitoring well 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

WI Witt International 

WM Walker Machine 
48 GW-Likelihood of Release 

Attribution

Walker Machine manufactured precision fabricated metal parts (also referred to as automated machine 

screw products) from 1953 until about 2002 (Refs. 5, pp. 1, 3; 8, p. 4; 19, p. 1; 27, p. 2). Langley 

purchased the property from Walker Machine in 2005 and began operations in 2006 (Refs. 13; 14). 

Langley manufactures wire cloth and perforated metal products with an emphasis on strainers and filters 

(Ref. 15). The facility used small amounts of TCE until 2012, and all solvents used on the property were 

reclaimed and recycled (Refs. 13; 40). 

Three critical materials are needed for the manufacture of automated machine screw parts: raw materials, 

cutting oils and coolants, and solvents (Ref. 27, pp. 35, 36). Typical solvents used to clean the 

component parts include mineral spirits, 1,1,1-TCA; PCE; and TCE (Ref. 27, pp. 45, 46, 47). Walker 

Machine used mineral spirits to clean metal parts and 1,1,1- TCA to clean brass parts (Refs. 5; 16). 

The breakdown products of TCE include 1,1-DCE; cis-1,2-DCE; and vinyl chloride. Similarly, the 

breakdown products of PCE include TCE; 1,1-DCE; cis-1,2-DCE; and vinyl chloride (Ref. 26, p. 24). 

These breakdown products are a result of natural biodegradation, referred to as reductive dechlorination 

(Ref. 26, p. 23). In addition, 1,1-DCA is a breakdown product of 1,1,1-TCA (Refs. 26, p. B4-61; 33, p. 

58). 

Walker Machine discharged spent solvent onto the ground and into a sewer drain located in the rear of the 

building (Ref. 18). Solvent tanks located inside the manufacturing building were not properly grounded 

(Ref. 18). Walker Machine also used an oil/water separator (Source No. 2) located near the former AST 

(Refs. 11, p. 2; 12, p. 3). The oil/water separator is currently located on the property. A sample collected 

from material inside the oil/water separator contained cis-1,2-DCE and vinyl chloride (Refs. 8, p. 4; 11, 

pp. 6, 7, 114, 115). A rusted and flattened drum labeled TCE along with other drum parts were observed 

in the wooded area on the property, south of the manufacturing building (Refs. 12, pp. 15, 52, 68; 62, p. 

i). 

Solvents typically used to degrease metal parts (1,1,1-TCA; PCE; and TCE) have been found in 

subsurface soil samples collected from Source No. 1. Source No. 1 is an area of contaminated soil 

resulting from automated machine screw operations (disposal practices). In addition, 1,1-DCA 

(breakdown product of 1,1,1-TCA); 1,1-DCE; and cis-1,2-DCE (breakdown product of PCE and TCE) 

have been found in subsurface soil samples collected from Source No. 1 (Refs. 8, p. 4; 12, pp. 54, 88, 89, 

90, 93, 94, 103, 108, 114; 16; 20, pp. 71, 75; 26, pp. 24, B4-61). A waste sample collected from Source 

No. 2 (an oil/water separator located about 35 feet south of the manufacturing building) contained cis-1,2-

DCE and vinyl chloride (Refs. 8, p. 4; 11, pp. 6, 7, 114, 115). Cis-1,2-DCE and vinyl chloride are 

breakdown products of PCE and TCE (Ref. 26, p. 24). As shown in Tables 2 and 3 of this HRS 

documentation record, Source 1 hazardous substances were detected as deep as 30 feet bgs; this shows 

that contamination has migrated downward through the soil towards the water table. And, ground water 

was noted to be present at approximately 60 feet bgs during the February 2010 construction of well WMMW-05, located within the area covered by Source 1 (Ref. 19, p. 107; Figures 3 and 4 of this HRS 

documentation record). 

Ground water underlying and in the vicinity of Source Nos. 1 and 2 contains concentrations of 1,1,1-

TCA; PCE; TCE; and their degradation products (Refs. 12, p. 11; 26, p. 24; 33, pp. 53, 58). During the 

March 2009 Witt International SI, ground water samples were collected from permanent monitoring wells 

installed on the Walker Machine and Witt International properties (Ref. 22, pp. 1, 9). The greatest 

concentrations of 1,1,1-TCA; 1,1-DCA; and PCE and its degradation products were detected in WMMW-03 located adjacent to the oil/water separator (Source No. 2) (Refs. 12, p. 3; 22, p. 10). During the 

February 2010 Walker Machine Reassessment, ground water samples collected from permanent 

monitoring wells installed on the Walker Machine and Witt International properties revealed the greatest 

concentrations of 1,1,1-TCA; 1,1-DCA; and PCE and its degradation products in WM-MW-03, located 

adjacent to the oil/water separator (Source No. 2) (Refs. 12, p. 3; 19, pp. 10, 11). 
49 GW-Likelihood of Release 

During the 2011 TDEC SI, the permanent monitoring wells installed at Witt International and Walker 

Machine properties were gauged and subsequent potentiometric mapping revealed that, locally, ground 

water was flowing radially from monitoring well WI-MW-01 and north from monitoring well WM-MW04 (Refs. 12, p. 62; 71). Monitoring wells WI-MW-01 (installed on the Witt property) and WM-MW-04 

(installed south of the Walker Machine property) are hydraulically upgradient or sidegradient of the 

release monitoring wells WM-MW-03, WM-MW-05, and WI-MW-02 as well as Source Nos. 1 and 2 and 

were selected to represent background conditions (Refs. 12, pp. 62, 64; 71). The greatest concentrations 

of PCE (1,500 μg/L), TCE (120 μg/L), and cis-1,2-DCE (120 μg/L) were detected in monitoring wells 

WM-MW-03 and WM-MW-05, both of which are located adjacent to the oil/water separator (Ref. 12, pp. 

3, 11, 64). The greatest concentration of 1,1,1-TCA (77 μg/L) was detected in monitoring well WI-MW02, located near the rear of the Walker Machine manufacturing building and about 75 feet west of Source 

No. 1 (Ref. 12, pp. 11, 64). The sample collected from WI-MW-02 also contained TCE, 1,1-DCE, and 

cis-1,2-DCE. These contaminants detected in the sample could be the result of past discharges of spent 

solvent onto the ground and into a sewer drain located in the rear of the building (Ref. 18). 

During the 2012 TDEC ESI, the permanent monitoring wells installed at the Witt International and 

Walker Machine properties were gauged and subsequent potentiometric mapping revealed that ground 

water was flowing radially from WI-MW-01 during the time of sampling (Ref. 20, p. 73). Permanent 

monitoring wells WM-MW-01, WM-MW-02, WM-MW-04, and WI-MW-01 surround Source Nos. 1 and 

2 and were selected to represent background conditions in an effort to delineate releases from the sources 

(Refs. 20, p. 72) (see Figures 3 and 4 of this HRS documentation record). The greatest concentrations of 

PCE (2,000 μg/L); TCE (150 μg/L); cis-1,2-DCE (160 μg/L); 1,1,1-TCA (72 μg/L); and 1,1,1-DCA were 

detected in monitoring wells WM-MW-03 and WM-MW-05, located adjacent to the oil/water separator 

(Refs. 8, p. 11; 12, p. 3; 20, p. 72). 

The permanent monitoring wells located on the Walker Machine and Witt International properties chosen 

to represent background conditions for the April 2011 and June 2012 sampling events were either 

upgradient/sidegradient (WI-MW-01 and WM-MW-04, April 2011) or surround (WM-MW-01, WMMW-02, WM-MW-04, WI-MW-01, June 2012) Source Nos. 1 and 2. The background wells contain 

concentrations of 1,1,1-TCA; 1,1-DCA; and PCE and its degradation products at significantly lower 

concentrations than detected in permanent monitoring wells underlying or adjacent to Source Nos. 1 and 2 

(WM-MW-03 and WM-MW-05, and WI-MW-02) (see Section 3.1.1, Observed Release of this HRS 

documentation record). The detections of 1,1,1-TCA; 1,1-DCA; and PCE and its degradation products in 

the wells chosen to represent background conditions might be a result of variability in ground water flow 

direction. 

Significant concentrations of 1,1,1-TCA, PCE and TCE and their degradation products in ground water 

samples collected from ground water underlying Source Nos. 1 and 2, as well as lower concentrations in 

ground water samples collected directly upgradient or surrounding Source Nos. 1 and 2, indicate that a 

release has occurred or is occurring on the Walker Machine property. Ground water samples collected on 

the adjacent Witt International property and from the permanent monitoring well installed on Halley 

Street also contain 1,1,1-TCA and PCE and TCE and their degradation products. However, samples 

collected from ground water underlying Source Nos. 1 and 2 contain significantly greater concentrations 

of these constituents (see Section 3.1.1, Observed Release of the HRS documentation record). 

No NPL sites are located within a 1-mile radius of the Walker Machine property (Ref. 64, pp. i, 18, 20, 

24, 28). Six EPA-regulated facilities are located in the immediate vicinity of the Walker Machine 

property and include Witt International, Constar Inc., Craig Lumber Corp., Durand Raute Corp., Floratine 

Products Group Inc., and Wilson Metal Products (Ref. 64, pp. i, 1 through 17). Of these facilities, Witt 

International, Constar Inc., and Durand Raute Corp., could be possible contributors to ground water 

contamination in the area. 

Witt International, EPA ID No. TNN000410339, is located adjacent to the Walker Machine property 

(Refs. 22, p. 3; 64, p. 1). The facility manufactured commercial heat transfer equipment and components 

from 1961 to 1999 (Refs. 23; 24; 25). The solvent used to degrease the metal parts is not known; 
50 GW-Likelihood of Release 

however, TCE reportedly was the primary solvent used to degrease and clean commercial heat transfer 

equipment and components (Ref. 22, p. 1). But, no soil source has been identified at Witt International; 

subsurface soil samples collected from the Witt International property in 2009 did not contain chlorinated 

solvents at concentration exceeding their MRLs (Refs. 22, pp. 7, 8, 9, 92, 93, 96, 97, 104 through 109; 26, 

p. 24). 

Constar Inc., EPA ID No. TND059841254, is a plastic bottle manufacturer located about 0.15 mile west 

and downgradient of sources on the Walker Machine property (Refs. 64, pp. 4, 29; 69, p. 72). The facility 

uses halogenated solvents as a degreaser/cleaner for machine parts of plastic molding equipment (Ref. 72, 

pp. 4, 7, 8, 9). Durand Raute Corp, EPA ID No. TND982087314, is inactive. The facility is located 

about 0.25 mile southeast and possibly upgradient of sources on the Walker Machine property (Refs. 40; 

64, pp. 8, 29; 69, p. 72). Industrial machinery was manufactured on the property and TCE was used as a 

cleaning agent (Ref. 64, p. 8; 72, p. 20). Waste TCE was generated from wiping down steel prior to 

painting or welding and from cleaning painting equipment (Ref. 72, p. 20). The waste was sent offsite to 

companies in Memphis, Tennessee (Ref. 72, pp. 20, 21). Operations began at the facility in 1979. A 

Hazardous Waste Stream Description form (listing TCE as waste) was submitted to the Tennessee 

Department of Health and Environment in 1989 (Ref. 72, pp. 19, 20). 

TDEC personnel researched the histories of various industries surrounding the Walker Machine property 

(Ref. 65). Industries to the south and east were researched in an effort to identify the reason for 

chlorinated solvent contamination in WM-MW-04 located along Halley Street to the south of sources at 

Walker Machine (Ref. 65). Possible sources identified included Gerdau Ameristeel and Rock Tenn. 

Gerdau Ameristeel is a storage facility for steel products (Ref. 65). Rock Tenn manufactures corrugated 

packaging products (Ref. 68, p. 2). 

During the 2012 TDEC ESI, a temporary monitoring well (screened between 63 and 73 feet bgs) was 

installed on the Rock Tenn property, about 350 feet southeast of sources on the Walker Machine property 

(Ref. 20, pp. 72, 87, 88) (see Figure 3 of this HRS documentation record). The temporary monitoring 

well is hydraulically downgradient of Durand Raute Corp and hydraulically upgradient of Walker 

Machine (Refs. 20, p. 72; 64, p. 8; 69, p. 72; 71) (see Figure 3 of this HRS documentation record). The 

ground water sample collected on the Rock Tenn property did not contain chlorinated solvents (Refs. 20, 

p. 79; 40; 65). 

TDEC personnel stated and USGS personnel verified that chlorinated solvents detected in WM-MW-04 

could be the result of a shallow sandstone layer located on the southern portion of the Walker Machine 

property that dips in the southern direction, causing the chlorinated solvents to follow the layer until 

ground water is reached. Once ground water is encountered, the chlorinated solvents follow the general 

direction of ground water flow (Refs. 65; 66). 

The hazardous substances listed below have been documented in Source Nos. 1 and 2 and in ground water 

underlying and in the vicinity of Source Nos. 1 and 2 on the Walker Machine property (see Tables 2, 3, 

and 5 in Section 2.2.2 for Source Nos. 1 and 2 and Tables 10, 12, 14, and 16 in Section 3.1.1, Observed 

Release, of this HRS documentation record). 

Hazardous Substances in the Release

Tetrachloroethylene 

Trichloroethylene 

1,1-Dichloroethylene 

cis-1,2-Dichloroethylene 

1,1,1-Trichloroethane 

1,1-Dichloroethane 

Ground Water Observed Release Factor Value: 550 
51 GW-Waste Characteristics 

3.1.2 POTENTIAL TO RELEASE

Potential to release was not evaluated for the Memphis Sand aquifer because an observed release has been 

documented (see Section 3.1.1 of this HRS documentation record). 

3.2 WASTE CHARACTERISTICS

3.2.1 TOXICITY/MOBILITY

The toxicity and mobility factor values for the hazardous substances detected in the source samples with 

containment factor values of greater than 0 are summarized in Table 17. The combined toxicity and 

mobility factor values are assigned in accordance with Reference 1, Section 3.2.1. 

TABLE 17: Ground Water Toxicity/Mobility

Hazardous

Substance

Source 

No.

Does 

Hazardous 

Substance 

Meet 

Observed 

Release? 

(Yes/No)

Toxicity 

Factor

Value

Mobility

Factor 

Value1

Toxicity/

Mobility

(Table 3-9) Reference

PCE 1 Yes 100 1 100 2, p. BI-11

TCE 1 Yes 1,000 1 1,000 2, p. BI-16

1,1-DCE 1 Yes 10 1 10 2, p. BI-5

cis-1,2-DCE 1, 2 Yes 1,000 1 1,000 2, p. BI-5

Vinyl chloride 2 No 10,000 1 10,000 2, p. BI-12

1,1-DCA 1 Yes 10 1 10 2, p. BI-4

1,1,1-TCA 1 Yes 1 1 1 2, p. BI-11

Notes: 

1

 Hazardous substance mobility factor values are based on a non-karst aquifer. In addition, hazardous substances 

meeting observed release criteria are assigned a mobility of 1 according to HRS Section 3.2.1.2. 

DCA Dichloroethane 

DCE Dichloroethylene 

No. Number 

PCE Tetrachloroethylene 

TCA Trichloroethane 

TCE Trichloroethylene 

 Toxicity/Mobility Factor Value: 10,000 

(Ref. 1, Table 3-9) 
52 GW-Waste Characteristics

3.2.2 HAZARDOUS WASTE QUANTITY

TABLE 18: Hazardous Waste Quantity

Source No. Source Type Source Hazardous Waste Quantity

1 Contaminated soil Undetermined, but greater than zero 

2 Tank Undetermined, but greater than zero 

The hazardous constituent quantity for Source No. 1 is not adequately determined. The source HWQ is 

undetermined, but greater than zero. 

The hazardous constituent quantity for Source No. 2 is not adequately determined. The oil/water 

separator appears to be a concrete structure with a metal lid. The dimensions and the amount of waste 

contained in the oil/water separator are not known (Ref. 40). The source HWQ is undetermined, but 

greater than zero. 

None of the targets evaluated for the ground water migration pathway are subject to Level I or Level II 

concentrations (see Section 3.3 of this HRS documentation record). As specified in Reference 1, Section 

2.4.2.2, an HWQ factor value of 10 was assigned. 

Hazardous Waste Quantity Factor Value: 10

(Ref. 1, Sec. 2.4.2.2)

3.2.3 WASTE CHARACTERISTICS FACTOR CATEGORY VALUE

The waste characteristics factor category was obtained by multiplying the toxicity, mobility, and HWQ 

factor values, subject to a maximum product of 1 × 108

. Based on this product, a value was assigned in 

accordance with Reference 1, Table 2-7. 

Toxicity/Mobility Factor Value: 10,000 

Hazardous Waste Quantity Factor Value: 10

Toxicity/Mobility Factor Value ×

Hazardous Waste Quantity Factor Value: 100,000 

Waste Characteristics Factor Category Value: 18

(Ref. 1, Table 2-7) 
53 GW-Targets 

3.3 TARGETS

Wells scored within a 4-mile radius of Source Nos. 1 and 2 at Walker Machine are drinking water wells 

from the Town of Collierville (Refs. 3; 60, pp. 1, 2, 3; 61, p. 1). The Town of Collierville operates four 

water treatment plants (WTP) supplied by 10 municipal wells within a 4-mile radius of Source No. 1 

(Refs. 3; 60, pp. 1, 2, 3). Specifically, the Mainstreet WTP operates three wells (Well Nos. 101, 102, and 

103) located within the 0.5- to 1-mile radius of Source Nos. 1 and 2; the Fleming Road WTP operates two 

wells (Well Nos. 501 and 502) located within the 1- to 2-mile radius of Source Nos. 1 and 2; the Frank 

Road WTP operates three wells (Well Nos. 301, 302, and 303) located within the 2- to 3-mile radius of 

Source Nos. 1 and 2; and the Distribution WTP operates two wells (Well Nos. 401 and 402) within the 3- 

to 4-mile radius of Source Nos. 1 and 2 (Refs. 3; 60, pp. 1, 2, 3). 

No single well in any WTP provides more than 40 percent of the total water supply, and the water from 

all WTPs can be mixed in the distribution lines. The Town of Collierville serves about 46,000 people or 

4,600 people per well (46,000 people ÷ 10 wells) (Ref. 60, p. 1). 

Municipal wells located within a 4-mile radius of Source Nos. 1 and 2 provide drinking water to about 

46,000 people. The population served by these wells per distance ring is distributed as follows: 0 to 0.25 

mile, 0 people; > 0.25 to 0.50 mile, 0 people; > 0.50 to 1 mile, 13,800 people; > 1 to 2 miles, 9,200 

people; > 2 to 3 miles, 13,800 people; > 3 to 4 miles, 9,200 people (Refs. 3; 60, pp. 1, 2, 3). 
54 GW -Targets 

TABLE 19: Municipal Drinking Water Wells within a 4-Mile Radius of Walker Machine

Memphis Sand Aquifer

Distance 

Ring

Miles Water System Name

Number 

of Wells Well No. 

Depth of 

Well 

(feet bgs)

Level I 

Cont. 

(Y/N)

Level II 

Cont. 

(Y/N)

Potential 

Cont. 

(Y/N)

Population 

Served References

0 to 0.25 NA 0 NA NA NA NA NA NA 3

> 0.25 to 0.5 NA 0 NA NA NA NA NA NA 3

> 0.5 to 1 Town of Collierville 3

Mainstreet 101 

Mainstreet 102

Mainstreet 103 

263

635

~ 273

NA NA Y 13,800 3; 60, pp. 1, 

3

> 1 to 2 Town of Collierville 2

Fleming Road 501 

Fleming Road 502 

384

284 NA NA Y 9,200 3; 60, pp. 1, 3

> 2 to 3 Town of Collierville 3

Frank Road 301

Frank Road 302 

Frank Road 303 

282

284

361

NA NA Y 13,800 3; 60, pp. 1, 

3

> 3 to 4 Town of Collierville 2

Distribution Parkway 401 

Distribution Parkway 402 

319

309 NA NA Y 9,200 3; 60, pp. 1, 3

 

Notes: 

 > Greater than 

 ~ Approximately 

 bgs Below ground surface 

Cont. Contamination 

ID Identification number 

 N No

NA Not applicable 

No. Number 

Y Yes
3.3.1 NEAREST WELL

Well ID: Town of Collierville municipal well 101 (Refs. 3; 60, pp. 1, 3). 

Level of Contamination (I, II, or potential): Potential 

If potential contamination, distance from source in miles: about 0.51 mile west of Source Nos. 1 and 2 at 

Walker Machine (Refs. 3; 60, pp. 1, 3). 

The Memphis Sand aquifer is continuous within the 4-mile radius of sources at Walker Machine (Ref. 53, 

pp. 1, 3). The Memphis Sand aquifer in Collierville, Tennessee, is unconfined (Refs. 48, p. 8; 51; 52, pp. 

8, 9; 53, p. 2; 67, p. 1). 

 Nearest Well Factor Value: 9 

(Ref. 1, Section 3.3.1) 

3.3.2 POPULATION

3.3.2.1 Level of Contamination

3.3.2.2 Level I Concentrations

No Level I concentrations have been identified. 

Level I Concentrations Factor Value: 0 

3.3.2.3 Level II Concentrations

No Level II concentrations have been identified. 

Level II Concentrations Factor Value: 0 

55 GW -Targets 
56 GW -Targets 

3.3.2.4 Potential Contamination

Distance-weighted population values for potential contamination ground water targets for the Memphis 

Sand aquifer are presented in Table 20. The Memphis Sand aquifer in Collierville, Tennessee, is 

unconfined (Refs. 48, p. 8; 51; 52, pp. 8, 9; 53, p. 2; 67, p. 1). The Jackson-upper Claiborne confining 

bed is not present in the vicinity of Source Nos. 1 and 2 at the Walker Machine property (Refs. 46, p. 12; 

48, pp. 5, 6; 50, Plate 1; 51; 67, p. 1). 

TABLE 20: Distance-Weighted Population Values 

Distance Category

(Miles) Population

Distance-Weighted 

Population Value

(Ref. 1, Table 3-

12) References

Greater than 0 to 1/4 0 0 3

Greater than 1/4 to 1/2 0 0 3

Greater than 1/2 to 1 13,800 5,224 3; 60, pp. 1, 3

Greater than 1 to 2 9,200 939 3 60, pp. 1, 3

Greater than 2 to 3 13,800 2,122 3; 60, pp. 1, 3

Greater than 3 to 4 9,200 417 3; 60, pp. 1, 3

Calculations: 

Sum of Distance - Weighted Population Values: 8,702 

Sum of Distance - Weighted Population Values ÷ 10: 870.2 

Potential Contamination Factor Value: 870.2 

3.3.3 RESOURCES

Resources were not scored because they do not significantly contribute to the overall site score. 

Resources Factor Value: NS

3.3.4 WELLHEAD PROTECTION AREA

The Federal Safe Drinking Water Act Amendments of 1986 established the initial step toward the 

prevention of contamination of public water supplies. Each state was required to develop a wellhead 

protection program to protect the water source of public water systems relying on ground water (Ref. 55, 

p. 5). Tennessee’s Wellhead Protection Program was approved by EPA on July 27, 1994 (Ref. 59, pp. 93, 

94). The Safe Drinking Water Act was amended in 1996 (Section 1453 of the 1996 Safe Drinking Water 

Act) and required that all states establish Source Water Assessment Programs detailing how each state 

would delineate source water protection areas, inventory significant contaminants in these areas, and 

determine the susceptibility of each public water supply to contamination (Ref. 55, p. 5). Tennessee’s 

Source Water Assessment Program was approved by EPA in November 1999 (Ref. 55, p. 5). The Town 

of Collierville municipal wells and their wellhead protection areas are located within the 4-mile radius of 

Source Nos. 1 and 2 at Walker Machine (Refs. 3; 60, pp. 1, 3; 67, pp. 1 through 10). 

Wellhead Protection Area Factor Value: 5.00