HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD COVER SHEET

Name of Site : Walker Machine Products, Inc.

EPA ID No. : TN N000410124

Contact Persons

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

John Nolen, Remedial Project Manager U.S. Environmental Protection Agency, Region 4 61 Forsyth Street, S.W., 11 th 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: Dec ember 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 WM 09 0411SB, located in the western portion of the property, about 15 feet

east of the manufa cturing 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,

th e 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 Migr ation NS

HRS SITE SCORE 50.00

Note:

NS Not scored2 WORKSHEET FOR COMPUTING HRS SITE SCORE

S Pathway S 2 Pathway

Ground Water Migration Pathway Score (S gw ) 100 .00 10,000

Surface Water Migration Pathway Score (S

sw ) NS NS

Soil Exposure Pathway Score (S

s ) NS NS

Air Migration Pathway Score (S

a ) NS NS

S 2

gw + S 2

sw + S 2

s + S 2

a 10,000

( S 2

gw + S 2

sw + S 2

s + S 2

a ) / 4 2,500 √ ( S 2

gw + S 2

sw + S 2

s + S 2

a ) / 4 50.00

Note:

NS = Not scored3 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 (h igher 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] c 100 100 .00 Ground Water Migration Pathway Score: 13. Pathway Score (S gw ), (highest value from line 12 for all aquifers e valuated) c 100 100 .00

Notes:

NS = Not scored

a = Ma ximum value applies to waste characteristics category

b = Maximum value not applicable

c = Do not round to nearest integerWashington StreetLegendProperty LocationMap Source:USGS 7.5 Minute Topographic Quadrangle Map:Collierville, TN 1975Refs. 5; 10; 12, p. 3File: L:\TTEMI-05-003-0156_Walker_Machine_Products_HRS\mxd\HRS Figures\Fig1_SiteLocation_012113.mxdKYALGAMSNCMOSCILVAARTENNESSEEFIGURE 1TTEMI-05-003-0156Walker Machine ProductsProperty LocationTDD No.:TDD Name:TennesseeShelbyColliervilleState:County:City:/0 500 1,000FeetShelbyCounty3/26/2013Date:ray.yeagerAnalyst:United StatesEnvironmental Protection AgencyRegion 4Walker Machine Products459 Washington St.Collierville, TN1:12,0004Location of Former ASTOil/Water SeparatorWitt International, Inc.Approximate Locationof TCE DrumsStorage buildingManufacturing BuildingNotes:AST - Aboveground Storage TankTCE - TrichloroethyleneMap Source:Bing Aerial ImageryRefs. 10; 12, pp. 1, 8, 40, 52, 78File: L:\TTEMI-05-003-0156_Walker_Machine_Products_HRS\mxd\HRS Figures\Fig2_SiteLayout_012113.mxdKYALGAMSNCMOSCILVAARTENNESSEEFIGURE 2TTEMI-05-003-0156Walker Machine ProductsProperty LayoutTDD No.:TDD Name:TennesseeShelbyColliervilleState:County:City:/ShelbyCounty3/26/2013Date:ray.yeagerAnalyst:United StatesEnvironmental Protection AgencyRegion 41:1,8000 80 160FeetLegendProperty Boundary!(Oil/Water Separator!(Approximate Locationof TCE Drums!(!(Washington St.Haley St. Southern Railroad5")Ò")Ò")Ò")Ò")©")©")©")©!<WM080411SBWM080411SBDWM090411SBWM120411SBWM24-0612-SBWM23-0612-SBWM23-0612-SBDWM21-0612-SB-AWM21-0612-SB-BWM22-0612-SBDWM-WA-01WM110411SBNotes:D – DuplicateESI - Expanded Site InvestigationSB – Subsurface SoilSI – Site InvestigationTDEC – Tennessee Department ofEnvironment and ConservationWA - WasteWM – Walker MachineMap Source:Bing Aerial ImageryRefs. 10; 11, pp. 6, 7, 8; 12, pp. 13, 54; 20, p. 71File: L:\TTEMI-05-003-0156_Walker_Machine_Products_HRS\mxd\HRS Figures\Fig3_SourceLocation_012313.mxdKYALGAMSNCMOSCILVAARTENNESSEEFIGURE 3TTEMI-05-003-0156Walker Machine ProductsSource LocationsTDD No.:TDD Name:TennesseeShelbyColliervilleState:County:City:ShelbyCounty3/26/2013Date:ray.yeagerAnalyst:United StatesEnvironmental Protection AgencyRegion 4/1:1,8000 80 160FeetLegendProperty Boundary")ÒSource No. 1 SubsurfaceSoil Sample!<Source No. 2")ÒSource No. 1 BackgroundSubsurface Soil SampleApril 2011 TDEC SIJune 2012 TDEC ESI")ÒSource No. 1 SubsurfaceSoil SampleSource No. 1Source LocationsWashington St.Haley St. Southern Railroad6"<)"<)"<)"<)@A@A@AWM-MW-02WM-MW-04WM-MW-01WI-MW-01WI-MW-02WM-MW-03WM-MW-05Notes:WI – Witt International, Inc.WM – Walker MachineMW – Monitoring WellMap Source:Bing Aerial ImageryRefs. 10; 12, p. 64; 20, p. 72File: L:\TTEMI-05-003-0156_Walker_Machine_Products_HRS\mxd\HRS Figures\Fig4_GroundWaterObservedRelease_012213.mxdKYALGAMSNCMOSCILVAARTENNESSEEFIGURE 4TTEMI-05-003-0156Walker Machine ProductsGround WaterObserved ReleaseTDD No.:TDD Name:TennesseeShelbyColliervilleState:County:City:/ShelbyCounty3/26/2013Date:ray.yeagerAnalyst:United StatesEnvironmental Protection AgencyRegion 41:1,8000 80 160FeetLegendProperty Boundary"<)Background Wells@AObserved Release WellsWashington St.Haley St. Southern Railroad78 REFERENCES

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.

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, Te nnessee, 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.

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. 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.

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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.

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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

Mac hine 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.

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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 a t: http://witt.htpgusa.com/about-us/htpg-history

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

of Chlor inated 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 f

or the Cleveland Advanced Manufacturing Program under Contract to the Energy Environment and Manufacturing Project of the Technology Reinvestment Program. Not dated.

84 Pa ges.

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, D ivision 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. T ennessee 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,

Tennesse e. 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

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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 DESCRIPTI ON

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 docum entation 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 (R ef s. 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 (R ef s. 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 of15

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 t hat 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 adjacen t 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 fro m 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 N o. 1 References

TDEC Pre

- CERCLIS

Screening 200 7 Surface s oil

Subsurface s oil

Ground w ater

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

- D CE 1,1

- DCE 1,1,1

- TCA 1,1

- DCA 19, pp. i, 5, 8,

11

TDEC Site

Investigation 2011 Subsurface soil

Ground 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 soil

Ground water PCE

TCE

c is

- 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- DC E (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); ci s-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

de te cted in sa mples WM03-0612-GW and WM05-0612- GW , located near the oil/water separator (Refs. 8, p. 11; 19, p. 3; 20, pp. 72, 77).Source Characterization 18 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). Sp ent 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, TD EC 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.Source Characterization 19 2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

April 2011 SI – Soil Samples

Subsur face 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 Branch es 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

W M090411SB 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; 4 1, p.

9Source Characterization 20 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

W M080411SBD 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,

11 6; 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; 4 1, 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. 9Source Characterization 21 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.Source Characterization 22 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 compar ed 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 backg round 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 Branch es 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

Samp le 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. 1 25; 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 bgsSource Characterization 23 TABLE 3: Analytical Results for Source No. 1

– June 2012

Samp le 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) . T hough 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.Source Characterization 24 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 Ref erences

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 scored2.4.2.1 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 (ft 2 ): >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

Source Characterization 25Source Characterization 26 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 separato r 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).Source Characterization 27 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 Branch es Quality System and Technical Procedures for Waste Sampling, SESDPROC-302-R0, February 2007 (Refs. 40; 63). The sample w as 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

MD L Method detection limit (Ref. 73, p. 1)

No. Number

WA Waste

WM Walker Machine Products, Inc.Source Characterization 28 2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

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

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

manufactu

ring building (Refs. 11, p. 132; 12, p. 3). A liner was not observed in the vicinity of Source No. 2 during sa mpling 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 scoredSource Characterization 29 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 ft 3
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: >0Source Characterization 30 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.GW -Likelihood of Release 31 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).

Th e 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

terrac e deposits of Pleistocene and Pliocene age range from a few feet to about 160 feet in thickness andare 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 compo se 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 l enses 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 su bordinate 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 isGW -Likelihood of Release 32 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 I sland 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 li gnite, and is about 100 feet thick in the Collierville area (Ref. 46, pp. 8, 20 ). The Old

B reastworks 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, downGW -Likelihood of Release 33 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

discusse d 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).GW -Likelihood of Release 34 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 aquif er (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 moni toring 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 No s. 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).GW -Likelihood of Release 35 SUMMARY OF AQUIFERS BEING EVALUATED

TABLE 8 : Summary of Aquifers Being Evaluated

Aqui fer 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 , p p

. 1 , 9

Notes:

NA Not applicable TDL Target distance limitGW -Likelihood of Release 36 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 cont ained 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 : Backgro und 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 A bout 2 60 feet

south of Source

No. 2 12, pp. 3, 8, 9

, 71, 72, 73 ; 19, pp. 104, 105; 41, p. 8GW -Likelihood of Release 37 TABLE 9 : Backgro und 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 041 1GW 72 52 to 7 2 4/26/2011 About 2 20 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 MachineGW -Likelihood of Release 38 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, p p. 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 MachineGW -Likelihood of Release 39 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 gr ound 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 WM

MW -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, p p

. 3, 8, 9

,

70, 72, 73 ; 40; 41, p. 8

WM

- MW

- 03 WM0 0411GWD 80 60 to 80 4/26/2011 Adjacent to

Source No. 2 12, pp. 3, 8, 9

,

70 , 7 1, 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 MachineGW -Likelihood of Release 40 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, p p

. 8, 142

WM

- MW

- 03 WM030411GW TCE 110 μg/L 12 μg/L 12, p p

. 8, 142

WM

- MW

- 03 WM030411GW 1,1

- DCE 210 μg/L 12 μg/L 12, p p

. 8, 140

WM

- MW

- 03 WM030411GW cis

- 1,2

- DCE 110 μg/L 12 μg/L 12, p p

. 8, 141

WM

- MW

- 03 WM030411GW 1,1,1

- TCA 72 μg/L 12 μg/L 12, p p

. 8, 140

WM

- MW

- 03 WM030411GWD PCE 1,300 μg/L 12 μg/L 12, p p

. 8, 145

WM

- MW

- 03 WM030411GWD TCE 110 μg/L 12 μg/L 12, p p

. 8, 145

WM

- MW

- 03 WM030411GWD 1,1

- DCE 190 μg/L 12 μg/L 12, p p

. 8, 143

WM

- MW

- 03 WM030411GWD cis

- 1,2

- DCE 110 μg/L 12 μg/L 12, p p

. 8, 14 4

WM

- MW

- 03 WM030411GWD 1,1,1

- TCA 67 μg/L 12 μg/L 12, p p

. 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 WM050411G W 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

- DC E 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 In ternational

WM Walker MachineGW -Likelihood of Release 41 June 2012

Background Samples

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

ev ent (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 r epresent 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 documenta tion 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

constructi on 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 fiel d 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- MW

01 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 Dept h (feet bgs ) Screened

Interval (feet bgs ) Date

Sampled Location References

WM

- MW

- 01 WM01

- 0612

- GW 80 60 to 80 6/26/2012 About 3 30 feet

east of Source

No. 2 8, p

. 9; 12, p. 3;

20, p p . 73 , 129,

135 ; 40; 41, p.

4 ;

WM

- MW

- 02 WM 02

- 0612

- GW 80 60 to 80 6/26/2012 About 200 feet

northeast of

Source No. 2 8, p

. 9; 12, p. 3;

20, p p . 73 , 129,

136 ; 40; 41, p. 4

WM

- MW

- 04 WM 04

- 0612

- GW 66.7 46.7 to

66.7 6/26/2012 About 2 60 feet

south of Source

No. 2 8, p

. 9; 12, p. 3;

19, pp. 104, 105; 20, p p . 73

, 130, 138 ; 41, p.

4GW -Likelihood of Release 42 TABLE 13 : Background Ground Water Samples

– Memphis Sand Aquifer

Monitoring

Well ID Sample ID Well Dept h (feet bgs ) Screened

Interval (feet bgs ) Date

Sampled Location References

WI

- MW

- 01 WI01

- 0612

- GW 72 52 to 72 6/2 7 /2012 2 20 feet

southwest of

Source No. 2 , on the Witt

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

20, p p . 73 , 131,

140 ; 5 4, 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 MachineGW -Likelihood of Release 43 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 1 4 : 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; 2 1, 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 μ g/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 limitGW -Likelihood of Release 44 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 MachineGW -Likelihood of Release 45 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 compar ed 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 Referenc e 20, page 73. Logbook

not es and f

ield 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 1 5 : 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

- 0 612

- GW 80 60 to 8 0 6/27/2012 Adjacent to

Source No. 2 8, p

. 9; 12, p. 3;

20, p p. 73 , 131,

137 ; 40 ; 41, p. 5

WM

- MW

- 03 WM03

- 0 612

- GWD 80 60 to 80 6/27/2012 Adjacent to

Source No. 2 8, p . 9; 12, p. 3;

20, p p. 73 , 131,

137 ; 40 ; 41, p. 5

WM

- MW

- 05 WM05

- 0 612

- 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,

p p . 73 , 131, 139 ; 41, p. 5

WI

- MW

- 02 WI02

- 0 612

- 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;

2 0, p p. 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 MachineGW -Likelihood of Release 46 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 1 6 : Analytical Results fo r June 2012

– Memphis Sand Aquifer

Monitoring

Well ID Sample ID Hazardous

Substance Concentration MRL References

WM

- MW

- 03 WM03

- 0 612

- 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 WM0 3

- 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

- 0 612

- GW 1,1,1

- TCA 68 μg/L 5.0 μg/L 8, p. 9 ; 21, p. 26GW -Likelihood of Release 47 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 Te trachloroethylene

TCA Trichloroethane TCE Trichloroethylene

WI Witt International

WM Walker MachineGW -Likelihood of Release 48 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; an d TCE) have been found in

subsur face 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 con tamination has migrated downward through the soil towards the water table. And, ground wate rwas 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 W itt 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).GW -Likelihood of Release 49 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- MW

04 (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- MW

02, 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;GW -Likelihood of Release 50 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 Depart ment 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. 6 5). 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

dir ection 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: 550GW -Waste Characteristics 51 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

Value 1 Toxicity/

Mobility (Table 3

- 9) Reference

PCE 1 Yes 100 1 100 2, p. BI

- 1 1

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 ,0 00 1 1 ,0 00 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

TC A Trichloroethane TCE Trichloroethylene

Toxi city/Mobility Factor Value: 10,000 (Ref. 1, Table 3-9)GW

- Waste Characteristics 52 3.2.2 HAZARDOUS WAS TE 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 a dequately 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 Lev el 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 × 10 8 . 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)GW -Targets 53 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-m ile 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).GW -Targets 54 TABLE 19: Municipal Drinking W ater 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

Fl eming 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 Yes3.3.1 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

GW -Targets 55GW -Targets 56 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 Me mphis Sand aquifer in Collierville, Tennessee, is

unconfine d (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