i COVER SHEET

Name of Site: West Troy Contaminated Aquifer
EPA ID No.: OH N 000508132
Contact Person United States Environmental Protection Agency (EPA), Region V: Patrick Hamblin 77 West Jackson Boulevard, Mail Code: SR

- 6J Chicago, Illinois 60604 ( 312 ) 886

- 63 12
Site Investigation: Jon R. Watterworth Ohio Environmental Protection Agency Division of Emergency and Remedial Response 401 East Fifth Street Dayton, Ohio 45402

- 2911 (937) 285

- 6062 (direct)
Pathways, Components or Threat Not Scored

The surface water migration , soil exposure , and air migration pathways are not scored as part of this Hazard Ranking System (HRS) evaluation. The surface water migration , soil exposure, and air migration pathways were not included because a release to these media does not significantly affect the listing decision, as based on the ground water pathway , the site scores well above 28.5 0

.1 HRS DOCUMENTATION RECORD

Name of Site: West Troy Contaminated Aquifer Date Prepared: March 201 2 EPA Region: V Street Address*: Adams Street and CR 25A City, County, State, Zip Code: Troy , Miami , Ohio, 45 37 3 (Figure 1) (Ref. 3, p. 1) General Location in State: W est

- c entral portion of Ohio in the C ity of Troy along the eastern and western bank s of the Great Miami River (Ref. 3, p. 1) Topographic Map: U.S. Geological Survey 7.5

- Minute Series Topographic Map of Troy , Ohio, Quadrangle , 196 1, P hotorevised 1982, P hotoinspected 1984 (Ref. 3, p. 1)

Latitude * : 40 ○ 2 ’ 4 7

. 07 ” North (Ref. 3, p. 1; Ref. 4, p. 1) Longitude * : 84 ○ 1 2 ’ 3 2

. 14 ” West (Ref. 3, p. 1; Ref. 4, p. 1) The latitude and longitude listed above mark the approximate location of the West Troy C ontaminated Aquifer, specifically approximate location of p ublic supply well PW

- 12 W (Ref. 4, pp. 1, 2)

.

* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area where the site is located. They represent one or more locations EPA considers to be part of the site based on the screening information EPA used to evaluate the site for NPL listing. EPA lists national priorities among the known “releases or threatened releases” of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has been “deposited, stored, placed, or otherwise come to be located.” Generally, HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to be addressed under 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 regarding where the contamination has come to be located.

Scores Ground Water Migration Pathway

- 100.00 Surface Water Migration Pathway

- N ot S cored Soil Exposure Pathway

- N ot S cored Air Migration Pathway

- N ot S core d HRS SITE SCORE 50.002 WORKSHEET FOR COMPUTING HRS SITE SCORE

S S 2 1. Ground Water Migration Pathway Score (S gw ) (from Table 3

- 1, line 13) 100 10,000

2a. Surface Water Overland/Flood Migration Component (from Table 4

- 1, line 30) NS

---
2b Ground Water to Surface Water Migration Component (from Table 4

- 25, line 28) NS

---
2c. Surface Water Migration Pathway Score (S sw ) (enter the larger of lines 2a and 2b as the pathway score) NS

---
3. Soil Exposure Path way Score (S s ) (from Table 5

- 1, line 22) NS

---
4. Air Migration Pathway Score (S a ) (from Table 6

- 1, line 12) NS

---
5. Total of S gw 2 + S sw 2 + S s 2 + S a 2 10,000

6. HRS Site Score 50.00 Divide the value on line 5 by 4 a nd take the square root.

Note: NS

– Not Scored3 HRS TABLE 3

- 1

– GROUND WATER MIGRATION PATHWAY SCORESHEET WEST TROY CONTAMINATED AQUIFER
Factor Categories and Factors Maximum Value Value Assigned

Likelihood of Release to an Aquifer: 1. Observed R elease 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 x (2b+ 2c+2d)) 500 NS 3. Likelihood o f Release (higher of lines 1 and 2e) 550 550 Waste Characteristics : 4. Toxicity/Mobility (a) 100 0 5. Hazardous Waste Quantity (a) 10 0 6. Waste Characteristics 100 1 8 Targets : 7. Nearest Well 50 50 8. Population: 8a

. Level I Concent rations (b) 35,540 8b

. Level II Concentrations (b) 0 8c

. Potential Contamination (b) NS 8d

. Population (lines 8a+8b+8c) (b) 35,540 9. Resources 5 5 10. Wellhead Protection Area 20 0 11. Targets (lines 7+8d+9+10) (b) 3 5 , 5 95 Gr ound Water Migration Score for an Aquifer 12. Aquifer Score [(lines 3X6X11)/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:
a. Maximum value app lies to waste characteristics category b. Maximum value not applicable
c. Do not round to nearest integer NS

- Not ScoredFigure 1

Site Location Map

750 E. Bunker Ct. Vernon Hills, Illinois 60061 WESTON SOLUTIONS, INC Prepared By:

TDD: S05-0008-1102-012 Prepared for:

DCN: 1381-2A-AMCN Contract No: Troy, Miami County, Ohio

West Troy Contaminated Aquifer EP-S5-06-04 U.S. EPA. REGION VJ:\CAD93\000\02707.dwg, 2/3/2012 11:14:58 AMFigure 2

ESI Sampling Locations

750 E. Bunker Ct. Vernon Hills, Illinois 60061 WESTON SOLUTIONS, INC Prepared By:

TDD: S05-0008-1102-012 Prepared for:

DCN: 1381-2A-AMCN Contract No: Troy, Miami County, Ohio

West Troy Contaminated Aquifer EP-S5-06-04 U.S. EPA. REGION VJ:\CAD93\000\02707.dwg, 2/3/2012 11:09:05 AMFigure 3

Monitoring Well Location Map

750 E. Bunker Ct. Vernon Hills, Illinois 60061 WESTON SOLUTIONS, INC Prepared By:

TDD: S05-0008-1102-012 Prepared for:

DCN: 1381-2A-AMCN Contract No: Troy, Miami County, Ohio

West Troy Contaminated Aquifer EP-S5-06-04 U.S. EPA. REGION VJ:\CAD93\000\02707.dwg, 2/3/2012 11:08:41 AM7 REFERENCES

1. U.S. Environmental Pr otection Agency (EPA). Hazard Ranking System , Final Rule , Title 40 Code of Federal Regulations (CFR), Part 300, 55 Federal Register (FR) 5153 2 . December 14, 1990. 13 8 p ages. http://www.epa.gov/superfund/sites/npl/hrsres/index.htm#HRS Rule

Note: A compl ete copy of the H azard R anking S ystem , Final Rule, can be obtained at the Regional docket upon request.

2. EPA. Superfund Chemical Data Matrix (SCDM), SCDM Data Versions: December 2, 20 11 , and October 23, 2006. Excerpt. 9 pages. A complete copy of SCDM is available at : http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm

. 3. U.S. Geological Survey (USGS). 1982. 7.5

- Minute Series Topographic Map: Troy, Ohio, Scale 1:24,00 0. Reproduced 05/03/2007. 1 page.

4. Weston Solutions Inc. (WESTON). Longitude and Latitude Calculations for West Troy Contaminated Aquifer Site by Brian Coninx , December 6 , 2011. 2 pages.

5. Ohio Environmental Protection Agency (Ohio EPA). Combined Prelim inary Assessment/Site Investigation Report, West Troy Contaminated Aquifer, Troy, Miami County, Ohio. September 21, 2001. 23 pages.

6. Ohio EPA. Expanded Site In spec tion , West Troy Contaminated Aquifer, Troy, Miami County, Ohio. September 27, 2005. 51 pa ges.
7. EPA. National Primary Drinking Water Regulations. 6 pages.

8. Ohio EPA. 201 1

. Supplemental Expanded Site In spec tion Report, West Troy Contaminated Aquifer, Troy, Miami County, Ohio. October 27 , 2011. 1 9 pages.
8a. Earth Tech Inc., Troy Ohio Well field Investigation Summary Report and Data Package, December 30, 1997. 102 pages

9. Ohio EPA. 201 1

. Draft Supplemental Expanded Site Investigation Report, Appendices, West Troy Contaminated Aquifer, Troy, Miami County, Ohio. February 28, 2011

. 19 50 pages.
9a. Ohio EPA, Interoffice Memo, SESI Pump Test Results Review, West Troy Contaminated Aquifer, November 30, 2010. 43 pages.
9b. Ohio EPA, SESI Pump Test Data, West Troy Contaminated Aquifer . June 2010

. 9c. Ohio EPA, SESI Pump Test Data, West Troy Contaminated Aquifer. June 2010.
9d. Ohio EPA, SESI Pump Test Data, West Troy Contaminated Aquifer. August

- September 2010.

9 e . Ohio EPA, Troy Well Study, Combined Uncorrected Water Depths , West Troy Contaminated Aquifer. Aug ust

- September 2010

.8 10. EPA

. SOM01.2 Volatile Target Compound List and Corresponding CRQL s

. Accessed on June 29, 2010. 2 pages. On

- line Address: http://www.epa.gov/oerrpa ge/superfund/programs/clp/som

vtarget.htm

11. Panterra Corporation. Well h ead Protection Area Delineation and Potential Contaminant Source Inventory. Volume 1. August 24, 1994. 155 pages.

12. WESTON. E

- mail Message to Omprakash Patel, WESTON, Regarding Tro y Text D ata F iles for D isch arge Measurements D own stream of Troy L ow D am. March 29, 2011, 42 pages.

13. University of Idaho

. Perchloroethylene (PCE) i n Dry Cleaning Establishments. December 2000. 17 pages.
14. City of Troy, Troy Water System Information. 1 pag e
15. Malcolm Pirnie

. Source Water Assessment and Protection Program Update. August 2010. 8 pages.

16. State of Ohio. Water Withdrawal Facility Registration Annual Report Form, City of Troy, Ohio. 7 January 2011. 2 pages.

17. WESTON. Record of Telep hone Conv ersation Record between Lauren Pesce , WESTON, and Tim R ay , Water Plant Superintendent , Troy Water Depa r tment, City of Troy, Ohio . March 9, 2011. 4 pages. 17a. WESTON. Record of Telephone Conversation, between Omprakash Patel, WESTON, and Tim Ray, Water Plant Superintendent, Troy Water Department, City of Troy, Ohio. November 22, 2011. 1 page.
18. U. S. Census Bureau

. Mi a mi County, Ohio, 2005

- 2009 American Community Survey 5

- Year Estimate s

. 2 pages.

19. WESTON. Record of Telep hone Conver sation, between Lauren Pesce , WESTON, and Don Knif e , Lead Operator, West Milton Village Water Department, West Milton, Ohio. March 23, 2011. 1 page.
20. Australian Government, Department of Sustainability, Environment, Water, Population and Communities

. Fa ct Sheet, Tetrachloroethylene. 3 pages. On

- line Address: 

### http://www.environment.gov.au/atmosphere/airquality/publications/sok/tetrachloroethylen e.h tml Accessed on July 29, 2011.

21. State of Wisconsin , Wisconsin Department of Health and Family Services, Information on Toxic Chemicals , Tric h loroethylene. December 2000. 2 pages.

22. Eco

- usa.net

. 1,1,1

- T richloroethane. 2 pages. On

- line Address: http ://www.eco

- usa.net/toxics/chemicals/1,1,1

- trichloroethane.shtml

23. Department of Health, New York State, Bureau of Toxic Substance Assessment

. Tenant Notification Fact Sheet for 1,2

- Dichloroethene. February 2011. 2 pages.

24. WESTON. Record of Telephone Co nversation between Lauren Pesce, WESTON, and Jeff Shields, Superintendent, Miami County Public Water System, Troy, Ohio. March 23, 2011. 1 page

.9 25. WESTON. Record of Telephone Conversation Record between Lauren Pesce, WESTON, and Tim Ray , Water Plant Supe rintendent, Troy Water Departm ent, City of Troy, Ohio. March 23, 2011. 1 page

. 26. WESTON. Calculations for City of Troy M unicipal P umpage P ercentage by Omprakash Patel. December 1 4 , 2011. 1 page.

27. Miami County Sanitary Engineering Department

. 2009 D rinking Water Quality Report. 3 pages.

28. USGS. 4

- Mile Radius Target Distance Map. 7.5

- Minute Series Topographic Map s with a Scale of 1:24,000 for the Following : Troy, Ohio , 1982 ; New Carlisle, Ohio, 1973; Christianburg, Ohio, 1992 ; Pleasant Hill, Ohio, 1961; West Milton, Ohio, Reproduced on May 3 , 2007

. 1 Page.10 1 .0 SITE DESCRIPTION The City of Troy is located in Miami County, Ohio, approximately 20 miles north of the City of Dayton (Ref. 5, p. 5 ). The City of Troy operates two well fields located a long a 1.25

- mile

- long segment of the Great Miami River in Miami County, Ohio (Ref s . 5, p. 5 ; 6, p. 5). Four wells are located in the W est W ell F ield, and five wells are located in the E ast W ell F ield (Ref. 6, p. 5). The W est W ell F ield is located on the east bank of the Great Miami River north of the downtown business district (Ref. 5, p. 5). The wells are screened in sand and gravel, and individual wells produce as much as 1,500 gallons per minute (gpm) (Ref s . 5, p. 5; 6, p. 5). Since 1986, volatile or ganic compounds (VOC) have been detected in well 12W in the west well field (Ref. 5. p. 5; Ref. 6, p. 6). Specifically , tetrachloroethene (PCE) has been detected in public well PW

- 12W in the W est W ell F ield at concentrations as high as 7.27 micrograms per liter (μg/L) and in finished water at the water treatment plant at concentrations as high as 1.56 μg/L (Ref s , 5, p. 5; 6, p. 6). The federal drinking water maximum contaminant level (MCL) for PCE is 5 μg/L (Ref s

. 5, p. 6; 6, p. 6 ; 7, p. 3).

The West Troy Contaminated Aquifer is a ground water plume of chlorinated solvents in the w est w ell f ield in the City of Troy, Miami County, Ohio (Figure 1) . The site has been characterized as a ground water plume with no identified source. The plume has been shown to include volatile organic compounds (VOCs) at levels above background in at least one public drinking water supply well in the City of Troy’s west well field. Tetrachloroethene ( PCE ) is the primary chlorinated solvent detected in the city well and other wel ls defining the plume (Refs. 6, p. 11; 8, p p . 13 , 14 )

. Trichloroethene (TCE) and cis

- 1,2

- dichloroethene (DCE) also have been detected in drinking water and monitoring wells (Ref. 6, pp. 10, 11) . The site scoring is based on a Level I concentration of PCE d etected in city well PW

- 12W. A National Priorit ies List s ite with a chlorinated solvent ground water plume is located south of the West Troy Contaminated Aquifer.

The location of the ground water plume was approximated based on results for ground water samples collected from public wells, monitoring wells, and direct

- push sampling devices (Figure 1)

. The precise extent of the ground water plume and possible source(s) of ground water contamination have not yet been identified. The rough outline of the pl ume extends from the location of the former Wampler Buick/GMC property at 507 and 515 N. Elm Street in Troy in a southeasterly direction across (under) the Great Miami River and then to the City of Troy’s west well field on the east side of the river (Figu re 1)

.11 Since ground water contamination was first detected in a city well in 1986, numerous investigations have been conducted to determine the source and extent of the contamination. Several facilities and properties were identified as possible sources in investigations beginning in 1991 and continuing through 2010 (Ref s . 5, pp. 5 , 6; 6, p. 6; 7, p. 3) . These investigations found properties, including the former Wampler Buick/GMC facility and the Hobart

- Lytle Road landfill, were associated with VOC conta mination (Ref. 5, p. 6) . PCE and TCE were detected in soil samples taken from the landfill, but these contaminants were not detected in ground water sampling at the facility (Ref. 5, p p . 6 , 7 ) . Ground water sampling at the former Wampler Buick/GMC property in 1997, during a preliminary assessment/site inspection (PA/SI) conducted by Ohio Environmental Protection Agency (Ohio EPA) in 2001, an expanded site inspection (ESI) in 2005 and a supplemental ESI in 2010 all detected PCE in ground water (Ref s . 5, p p

. 6, 8; 6, p.10; 8, p. 1 7 )

. Soil samples collected in 1999 by ITW

- Hobart at the Hobart

- Lytle Road landfill, located about 4,600 feet northwest of the West Troy Contaminated Aquifer, were found to be contaminated with solvents, including TCE. S oil samples co llected at the landfill in 2000 had detections of PCE and TCE ( Ref. 5, p p

. 6, 7 ) . Ground water samples taken by Ohio EPA in 2001 from a property south and east of the landfill showed contamination with benzene, ethyl benzene and xylene, but not PCE, TCE or cis

- 1,2

- DCE ( Ref. 5, p. 7 )

. PCE was detected in one monitoring well at another location that was considered a possible source, the Hobart Lagoon, located about 600 feet southeast of the Wampler Buick/GMC property, and about 100 feet to the west of the Gre at Miami River. This well was located between the Wampler Buick/GMC property and Hobart Lagoon and the concentration of PCE was less than at the Wampler Buick / GMC property (Ref. 6, p.6). Therefore, it was concluded that PCE was not released from the Hoba rt Lagoon (Ref. 6, p. 6).

The supplemental ESI conducted by Ohio EPA in 2010 confirmed contamination of wells PW

- 12W and
PW

- 3W in the City of Troy’s west well field (Refs. 8, p. 1 4 ; 9, p. 1941) . The supplemental ESI also included a pump test of city well s in the west well field; based on the results of the test, Ohio EPA concluded that there is a hydraulic connection between the shallow sands and gravels on the west side of the Great Miami River (where possible contaminant sources are located and where VO C contamination has been detected) and the deeper sands and gravels on the east side of the river from which the city wells draw (Ref. 8, p. 1 5 )

. In 2010, monitoring wells at the former Wampler Buick/GMC property again showed contamination with VOCs, inclu ding PCE (Refs. 8, p. 14; 9, pp. 1941, 1942) . Based on this and previous investigations, Ohio EPA concluded that Wampler Buick/GMC, and other possible sources investigated, could not be12 confirmed as at least contributing to the observed VOC contamination i n the ground water plume impacting public drinking water well PW

- 12W, and the source was characterized as a ground water plume with no identified source.

A ground water sample collected south of Morgan’s Ditch in 1997 contained PCE , and this finding may in dicate a source located west of the Wampler Buick/GMC properties (Ref s . 8, p p

. 8, 16 ; 8A, p. 25 ). The Troy Filler Metals Operation at 101 Trade Square East is located west of the Wampler Buick/GMC properties and PW

- 12W and has a history of solvent use , in cluding use of chlorinated compounds (Ref. 8, p. 1 7 ). An a dditional 5 facilities potentially upgradient of the site that ha ve potentially used solvents were also identified. These facilities are described in detail in the “Description of O ther P ossible S ources ” section of this HRS documentation record. The identified facilities are summarized below:

1. T h e Re

- store: The Re

- store is located at 500 North Elm Street, in Troy, Ohio (Ref. 9, p. 87)

.

2. Webster’s Auto : Webster’s Auto repair is located at 525 Nor th Elm Street, Troy, Ohio (Ref. 9, p. 90)

.

3. Miami County Garage : Miami County Garage is located at 670 Harrison Street, Troy, Ohio (Ref. 9, p. 90)

.

4. Former Trojan Specialties : Former Trojan Specialties is located at 745 Harrison Street, Troy, Ohio (Ref . 9, p. 91 ). A vacant commercial building is present at this location (Ref. 9, p. 91 ). Previously, Trojan Specialties was present at this location (Ref. 9, p. 91 )



### 5. Action Tire Auto Center : Action Tire and Auto Center is located at 816 Harrison Street,
Tr oy, Ohio (Ref. 9, p. 91).

1.1 INVESTIGATIONS PERFORMED AT THE SITE

In 199 1 , t he Ohio EPA began searching for a source of the VOC contamination (Ref. 5 , p. 6)

. In 1997, the Ohio EPA collected direct

- push technology ground water samples in and around the Wampler Buick/GMC location ( Ref. 5 , p. 6).

In 1999, ITW

- Hobart collected soil samples from the Hobart

- Lytle Road landfill , and results indicated that solvents , including trichloroethene (TCE), were present in soil (Ref. 5, p. 6).

In 2001, t he Ohio EP A conducted a combined preliminary assessment/site investigation (PA/SI) and advanced four direct

- push borings to approximately 10 to 12 feet below ground surface (bgs) at an13 agricultural field south of the Earhart Petroleum facility and east of the Hobart

- Lytle Road landfill ( Ref. 5 , p. 6). The borings were advanced to determine if any VOCs were migrating to the east and south ( Ref. 5 , p. 7). Soil samples were collected from the southernmost direct

- push borehole for visual and laboratory analysis ( Ref. 5 , p. 6). A soil sample from 8 to 9 feet bgs also was collected and sent to a Contract Laboratory Program ( CLP ) laboratory for analysis for Target Compound List ( TCL ) VOCs ( Ref. 5 , p. 6). Gr ound water sample s were collected from 4 monitoring wells at the Earhart Petroleum property , 4 monitoring wells at the Hobart Lagoon, 6 city monitoring wells, and 11 monitoring wells at the Wampler Buick/GMC facility ( Ref. 5 , p. 6). Troy production wells PW

- 4W and PW

- 12W also were sampled (Ref. 5, p. 7 ). Because the s creened interval of the city monitoring wells varied from 46 to 140 feet bgs , multiple samples were collected from each well at different depths ( Ref. 5 , pp. 6 , 7). The water samples from the Earhart Petroleum property , the city wells, and the Hobart Lago on were sent to a CLP laboratory for analysis for TCL VOCs ( Ref. 5 , p. 6). The samples from the Wampler Buick/GMC facility were sent to a mobile laboratory at the Miamisburg Contaminated Aquifer expanded site investigation (ESI) location for VOC analysis using U.S. Environmental Protection Agency (EPA) M ethod 8260 ( Ref. 5 , p. 7 ). PCE and other VOCs were detected in several wells sampled at the Wampler Buick/GMC facility (Ref. 5, pp. 7 , 8). PCE also was detected in City of Troy production well 12W (Ref. 5, p. 8).

In 200 5 , the Ohio EPA completed an ESI at the West Troy Contaminated Aquifer. The ESI focused on the two properties at 507 and 515 N. Elm Street located on the east side of N. Elm Street just north of the C ity of Troy corporation limits ( Ref. 6 , p. 5). Ohio EPA’s contractor, Tetra Tech EM, Inc. (Tetra Tech) , advanced 11 direct

- push borings at the properties to approximately 44 feet bgs ( Ref. 6 , p. 8). Continuous soil samples were collected from borings GP86, GP87, and GP

- 90 using a core barrel sleeved with a plastic liner ( Ref. 6 , p. 8). The soil samples were screened using a p hotoionization detector, but no samples were submitted for laboratory analysis because the VOC field screening results did not exceed the screening criteria ( Ref. 6 , p. 8 ). Three water samples were collected from 10 of the 11 borings at the following approximate depths: 20 to 24, 32 to 36, and 40 to 44 feet bgs ( Ref. 6 , p. 8). Two water samples also were collected from GP

- 86B at 32 to 36 and 40 to 44 feet bgs ( Ref. 6 , p. 8). The samples were submitted to Severn Trent Laboratories for VOC analysis using EPA SW

- 846 Method 8260B ( Ref. 6 , p. 8). The samples w ith t he highest concentrations of PCE were found in borings GP

- 84 (41 μ g/ L ) at 20 to 24 feet bgs and GP

- 86B (32 μ g/ L ) at 32 to 36 feet bgs (Ref. 6, p. 8).

In 2005, as part of the ESI, Tetra Tech installed five monitoring wells (OEPA

- 14, OEPA

- 15, OEPA

- 16, OEPA

- 17, and OEPA

- 18) at 507 and 515 N. Elm Street ( Ref. 6 , p. 10). Th e well locations and the screened intervals were based on the direct

- push sampling results , with the goal of verifying the previous detections of PCE and establishing background concentrations ( Ref. 6 , p. 10). On June 13 and 14, 2005 ,14 t he five new monitor ing wells, two upgradient monitoring wells owned by the C ity of Troy, two existing monitoring wells at 515 N. Elm Street, and city production wells 4W and 12W were sampled ( Ref. 6 , p. 10). The monitoring wells were sampled with a peristaltic pump using th e micropurging technique ( Ref.
6 , p. 10). The two production wells were sampled at the pump houses using ports installed by the city for monitoring purposes ( Ref. 6 , p. 10). A4 Scientific Laboratory analyzed t he samples for VOC s using CLP Scope of Work ( SOW ) OLC03.2 methods ( Ref. 6 , pp. 21 , 22). The highest concentration of PCE was found in monitoring well OEPA

- 17 at 21 μ g/ L (Ref. 6, p. 10). PCE was found in city well 12W at 5.7
μ g/ L (Ref. 6, p. 10).

As part of the PA/ SI, t he Ohio EPA also evaluated other facilities that may be responsible for the release of PCE to ground water , including a Hobart Brothers Corporation complex located 1 , 800 feet west of the West Troy Contaminated Aquifer ; the Hobart

- Lytle Road landfill located 4 , 600 feet northwest of the West Troy Contaminated Aquifer; and several small commercial facilities located on County Road 25A north of the S ite ( Ref. 6 , p. 6 ). No evidence regarding the disposal of PCE was obtained from any neighboring facilities ( Ref. 6 , p. 6 ).

In 2010, t he Ohio EPA conducted a s upplemental ESI of the West Troy Contaminated Aquifer (Ref. 8, p. 1)

. During Phase I of the supplem ental ESI , five public wells in the W est W ell F ield were sampled before and after the pump test (Ref. 8, p. 5) . Production well samples were analyzed for VOCs through the EPA CLP (Ref. 8, p. 5)

. During Phase 2 of the supplemental ESI , 5 W est Well Field p roduction wells, 24 monitoring wells , and 5 private production wells were sampled (Ref. 8, p. 6 )

. KAP Technologies Inc. and A4 Scientific Inc. analyzed t he ground water samples for VOCs using the CLP SOW SOM01.2 (Ref. 9, pp. 1311, 1420, 1505, 1663, and 18 21). Ohio EPA Division of Drinking and Ground W aters (DDAGW) staff e valuated pump test results and concluded that hydraulic communication exists between the shallow sands and gravels on the west side of the Great Miami River and the deeper sands and grave ls on the east side of the river where PW

- 12W is located (Ref. 8 , p. 6 ).

2.2 SOURCE CHARACTERIZATION

2.2.1 Source Identification

Source Number : 1 Source Type : Other

– Ground water plume with no identified source Description and Location of Source (with reference to a map of the site):15 Source 1 is a contaminated ground water plume containing primarily PCE , with no identified source. Other chlorinated solvents detected in ground water include TCE and cis

- 1,2

- DCE. In accordance with the Hazard Ranking Sy stem ( HRS ) , the plume itself is considered the source (Ref. 1, Sec. 1.1, p. 51587). As currently delineated, the Source 1 ground water plume extends from the properties at 507 and 515 N. Elm Street west of the City of Troy municipal West W ell F ield or we st of th e s e properties to the vicinity of Troy well 12W ( Ref s . 6 , p. 12 ; 8, p. 16 ) (Figure s 1, and 3 ) . Despite all the investigations performed to date, the ground water contamination cannot be attributed to any source with confidence (Ref. 8 , p. 6 )

. Th e extent of this plume has not yet been completely delineated but the plume has been characterized based on data from residential wells, monitoring wells , and public supply well s (Figure 3 ) gathered during previous investigations.

In April, May, and August 2001 , the Ohio EPA conducted a combined PA/SI at the West Troy Contaminated Aquifer (Ref. 5 , p p

. 4 , 5). The Ohio EPA advanced four direct

- push borings to approximately 10 to 12 feet bgs

. Ground water samples were collected from 4 monitoring wells at the Earhart Petroleum property , 4 monitoring wells at the Hobart Lagoon, 6 city monitoring wells, and 11 monitoring wells at the Wampler Buick/GMC location (Ref. 5 , p. 6). Troy production wells 4W and 12W also were sampled (Ref. 5, p. 7). The water samples from the Earhart Petroleum property , city wells, and the Hobart Lagoon were sent to a CLP laboratory for analysis for TCL VOCs ( Ref. 5 , p. 7 ). The samples from the Wampler Buick/GMC facility were sent to a mobile laboratory for VOC analysis using EPA
M eth od 8260 ( Ref. 5 , p. 7 ). PCE and other VOCs were detected in several wells sampled at the Wampler Buick/GMC facility ( Ref. 5 , p p

. 7 , 8 ). PCE also was detected in City of Troy production well 12W ( Ref. 5, p. 8).

In May and June 2005, the Ohio EPA conducte d an ESI at the West Troy Contaminated Aquifer (Ref. 6 , p. 5). Ohio EPA’s contractor, Tetra Tech, advanced 11 direct

- push borings at the properties on 507 N. Elm Street and 517 N. Elm Street to approximately 44 feet bgs (Ref. 6, p p

. 5, 8). Continuous soi l samples were collected from borings GP86, GP87, and GP

- 90 using a core barrel sleeved with a plastic liner (Ref. 6, p. 8). The soil samples were screened using a photoionization detector, but no samples were submitted for laboratory analysis because the VOC field screening results did not exceed the screening criteria (Ref. 6, p. 8). Three water samples were collected from 10 of the 11 borings at the following approximate depths: 20 to 24, 32 to 36, and 40 to 44 feet bgs (Ref. 6, p. 8). Two water sampl es also were collected from GP

- 86B at 32 to 36 and 40 to 44 feet bgs (Ref. 6, p. 8). The samples w ith t he highest concentrations of PCE were found in borings GP

- 84 (41 μ g/ L ) at 20 to 24 feet bgs and GP

- 86B (32 μ g/ L ) at 32 to 36 feet bgs (Ref. 6, p. 8).16 During Phase I of the supplemental ESI , five public wells in the W est W ell F ield were sampled before and after the pump test (Ref. 8, p. 5). Production well samples wer e analyzed for VOCs through the EPA CLP (Ref. 8, p. 5). During Phase 2 of the supplemental ESI , 5 W est Well Field production wells, 24 monitoring wells , and 5 private production wells were sampled (Ref. 8, p. 6 ). KAP Technologies Inc. and A4 Scientific I nc. analyzed t he ground water samples for VOCs using the CLP SOW SOM01.2 (Ref. 9, pp. 1311, 1420, 1505, 1663, 1821). Ground water sampling results confirm ed that West Well Field wells
PW

- 12W and PW

- 3W are contaminated with VOCs (Ref. 8, p. 16). PCE was d etected at concentrations exceeding its MCL in PW

- 12W. TCE, DCE , and TCA were detected in PW

- 12W at concentrations below their respective MCLs (Ref. 8, p. 1 7 ). DCE was detected in PW

- 3W for the first time in supplemental ESI samples, but all detections w ere below the DCE MCL (Ref. 8, p. 1 7 ). TCA was detected in samples from two private production wells (non

- potable) on the west side of the Great Miami River (Ref. 8, p. 1 7 ). The City of Troy minimized pumping PW

- 12W and blended water from both well field s to reduce VOC concentrations to below detectable limits in finished water (Ref. 8, p. 1 7 ).

2.2.2 Hazardous Substances Associated with the Source The following ground water data are presented to illustrate the haz a rdous substances associated with Source 1. During the Phase I of the supplemental ESI , five public wells in the W est W ell F ield were sampled before and after the pump test (Ref. 8, p. 5). Production well samples were analyzed for VOCs through the EPA CLP (Ref. 8, p. 5). During Phase 2 of the supplemental ESI , 5 W est Well Field production wells, 24 monitoring wells , and 5 private production wells were sampled (Ref. 8, p. 6 ). KAP Technologies Inc. and A4 Scientific Inc. analyzed t he ground water samples for VOCs using the CLP SOW SOM01.2 (Ref. 9, pp. 1311, 1420, 1505, 1663, 1821). The hazardous substance associated with Source 1 is primarily PCE . H owever, TCE and cis

- 1,2

- DCE also have been detected in the unconsolidated aquifer (Ref. 8, p p

. 7, 8 ) . Figure 1 shows the location of Source 1.

Bac kground Levels :

- Background Level at Source 1

– Other

-- Contaminant Plume

Regional ground water flow is south following the Great Miami River valley (Ref. 8, p. 1 6 )

. Ground

water at Troy is part of the Great Miami River Buried Valley Aquifer System (Ref s

. 8, p. 1 6 ; 9, pp. 128 , 129). Based on available ground water flow information , monitoring wells MW

- C, MW

- E and MW

K are considered to be background (upgradient) wells. Figure 3 shows the background sampl ing locations. The contaminants of concern for th e West Troy Contaminated Aquifer (PCE; TCE; and cis

1,2

- DCE) were not detected in ground water samples collected from the background monitoring well17 locations (Ref. 9 , pp. 1602, 1603, 1722, 1723, 1725, 1726, 1728, 1729, 1731, 1732, 1734, 1735, 1737, 1738, 1861, 1862 ). The a bsence of contaminants of concern in the ground water samples suggests that the background locations to the depth of approximately 1 40 feet bgs lie outsi de the area of contamination.

Table 1 below summarizes background location informa tion and the concentrations of contaminants of concern for the site detected in ground water samples collected from each location.

TABLE 1 BACKGROUND LOCATION AND CONCENTRATION INFORMATION

Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Sc reen Interval or

Screen Length

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) References

MW

- E_S UC 25 15

- 12 5 E2509 7/19/2010 PCE 0.5 U 0.5 Ref s

. 6, p. 50; 9, pp. 1001, 1554, 1662

- 1669,1674, 1675, 1727

- 1729, 1787, 1930, 1949 ; 10, pp. 1 , 2 TCE 0.5 U 0.5

c is

- 1,2

- DCE 0.5 U 0.5

MW

- E_I UC 70 15

- 125 E2508 7/19/2010 PCE 0.5 U 0.5 Ref s . 6, p. 50; 9, pp. 1001, 1554, 1662

- 1669,1674, 1675, 1730

- 1732, 1787, 1929, 1949 ; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- E_D UC 122 15

- 125 E2507 7/19/2010 PCE 0.5 U 0.5 Ref s . 6, p. 50; 9, pp. 1001, 1504

- 1512,1517, 1518, 1554 1602

- 1605 , 1787, 1931 ; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- K_S UC 35 140 E2512 7/19/2010 PCE 0.5 U 0.5 Ref s . 9, pp. 898, 1554, 1787, 1820

- 1825, 1826, 1827, 1844, 1861

- 1863, 1917, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- K_I UC 75 140 E2511 7/19/2010 PCE 0.5 U 0.5 Ref s

. 9, pp. 898, 1554, 1662

- 1669,1676, TCE 0.5 U 0.5

c is

- 1,2

- DCE 0.5 U 0.518 Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Sc reen Interval or

Screen Length

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) References

1677, 1721

- 1723, 1787, 1916, 1949; 10, pp. 1 , 2 MW

- K_D UC 121 140 E2510 7/19/2010 PCE 0.5 U 0.5 Ref s . 9, pp. 898, 1662

- 1669,1676, 1677, 1724

- 1726, 1787, 1926, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- C_S UC 25 15

- 61 E2506 7/19/2010 PCE 0.5 U 0. 5 Ref s . 6, p. 50; 9, pp. 1001, 1662

- 1669,1674, 1675, 1733

- 1735, 1788, 1927, 1949; 10, pp. 1 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0. 5 U 0.5

MW

- C_D UC 50 15

- 61 E2505 7/19/2010 PCE 0. 5 U 0.5 Ref s . 6, p. 50; 9, pp. 1001, 1662

- 1669,1674, 1675, 1736

- 1738, 1788, 1928, 1949 ; 10, pp. 1 2 TCE 0. 5 U 0.5

c is

- 1,2

- DCE 0. 5 U 0.5

Notes: μg/L

– Microgram per liter bgs

– Below ground surface CRQL

– Contract

- Required Quantitation Limit (Ref. 10, pp. 1 and 2) DCE

- Dichloroethene PCE

– Tetrachloroethene T CE

- Trichloroethene U

– Analyte was analyzed for but was not detected above the reported sample quantitation limit (Ref. 9, pp. 1512, 1669, and 1825) UC

– Uncon solidate d aquifer

Contaminated Samples :

- Contaminated Samples at Source 1

– Contaminated Plume

Table 2 below summarizes t he results for ground water samples contaminated with PCE , TCE and DCE collected from monitoring wells and public supply wells at the West Troy Contaminated Aquifer

. Figure 3 of this HRS documentation rec ord s how s t he sampl ing locations except W

- OB

.19 TABLE 2 CONTAMINATED SAMPLE INFORMATION

Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) Re ferences

OEPA

- 14 UC 44 39

- 44 E2 49 5 7 / 21 / 1 0 PCE 8.7 0. 5 Refs. 6, p. 45; 9, pp. 1000, 1504

- 1512 , 1579, 1785, 1905 ; 10, pp. 1 , 2 OEPA

- 16 UC 2 5 15

- 25 E 2497 7/21/10 10 0. 5 Refs. 6, p. 47; 9 , pp. 1000, 1504

- 1512, 1585, 1785, 1907 ; 10, pp. 1 , 2 OEPA

- 17 UC 34 29

- 34 E24 98 7/21/10 18 0. 5 Refs. 6, p. 48; 9, pp. 1000, 1504

- 1512, 1588, 1785 , 1932; 10, pp. 1 , 2 P W

- 1 2W UC 86 66

- 86 E25 00 7/21/10 5.20 0.5 Ref s

. 6, pp. 3839; 9 , pp. 1504

- 1512, 1591 , 1785, 1911 ; 10, pp. 1 , 2

W

- 3 UC 33.20 NA E 2518 7/22/10 7.1 0.5 Ref s

. 9 , pp. 1504

- 1512, 1519

- 1520, 1556, 1923 , 1941 ; 10, pp. 1 , 2 W

- 8 UC 16.59 7.6

- 17.5 E2 5 22 7/22/10 3.9 0. 5 Ref s

. 9 , pp. 100 1 , 1504

- 1512, 1557, 1631, 1921 ; 10, pp. 1 , 2 W

- OB UC 34.45 NA E2521 7/22/10 6.5 0.5 Ref s

. 9 , pp. 1504

- 1512, 1557, 16 28 , 1919 ; 1 0, pp. 1 , 2 RW

- 5 UC NA NA E2 529 7/21/10 9.1 0.5 Ref s

. 9 , pp. 1820

- 1825, 1845, 1875, 1900 ; 10, pp. 1 , 2 PW

- 12W UC 86 66

- 86 E2500 7/21/10 TCE 0.81 0. 5 Refs. 6, pp.38, 39; 9 , pp. 1504

- 1512 , 1591 1785, 1911 ; 10, pp.1, 220 Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) Re ferences

PW

- 12W UC 86 66

- 86 E2500 7/21/10 Ci s

- 1,2

- DCE 1.1 0.5 Refs. 6, pp.38, 39; 9 , pp. 1504

- 1512, 1590, 1785, 1911 ;10, pp.1, 2

Notes: μg/L

– Microgram per liter bgs

– Below ground surface CRQL

– Contract

- Required Quantitation Limit (Ref. 10, pp. 1 and 2) DCE

- Dichloroethene PCE

– Tetra chloroethene TCE

- Trichloroethene U

– Analyte was analyzed for but was not detected above the reported sample quantitation limit (Ref. 9, pp. 1512, 1669, and 1825) UC

– Uncon solidated aquifer

The background and downgradient monitoring well samples were co llected within the same timeframe (between July 19 and 22 , 20 10 ) (Ref. 9 , pp. 1904

- 1937 ). The samples were collected with peristaltic
pump s using a low

- flow sampling technique ( Ref. 9, pp. 1904

- 1937 ). The ground water samples were collected after the fol lowing field parameters had stabilized: pH, conductivity, dissolved oxygen (DO),

t emperature, and oxidation

- reduction potential ( Ref. 9, pp. 1904

- 1937 ). The samples were analyzed by the U.S. EPA CLP) for VOCs using same method (Ref. 9, pp. 1504

- 1512 ).

Th e ground water samples from private and public wells collected on July 21, 2010 , are considered in this HRS documentation record package (Ref. 9 , pp. 1908

- 1912 ). The samples were collected on the same day by the same sampler (Ref. 9 , pp. 1908

- 1912 ). The samples were analyzed by the U.S. EPA CLP for VOCs ( Ref. 9, pp. 1504

- 1512 , 1820

- 1825 ).

List of Hazardous Substances Associated with Source:

The following hazardous substances are associated with the source:

• P CE

• c is

- 1,2

- DCE

• T CE21 2.2.3 Hazardous Substances Ava ilable to a Pathway

The soil boring investigations within the plume have shown that there is no liner, maintained engineered cover, functioning and maintained run

- on control system, runoff management system, or functioning leachate collection and removal s ystem (Ref. 6, pp. 42

- 49 )

. Furthermore, a ground water release of hazardous constituents from unknown sources is documented based on analytical results for ground water samples collected from the plume . Therefore, the Containment Factor Value (CFV) for t he ground water migration pathway was assigned a maximum value of 10 (Ref. 1, Section 3.1.2.1, Table 3

- 2 , p. 51596 ). The maximum CFV reflects the minimum level of containment. A source is assigned the maximum CFV if there is evidence that hazardous subst ances have migrated from the source area or that there is no liner, maintained engineered cover, functioning leachate collection and removal system, or functioning and maintained run

- on control system and runoff management system (Ref. 1, Section 3.1.2.1, Table 3

- 2, p. 51596).

T he following substances are identified as having been released to the ground water migration pathway: PCE ; TCE ; and cis

- 1,2

- DCE . Table 3 below summarizes the CFVs for each pathway.

TABLE 3 CONTAINMENT FACTOR VALUE SUMMARY

Release Description CFV Reference Gas Release to Air Not Scored NA Particulate Release to Air Not Scored NA Release to Ground Water: Because of evidence of hazardous substances migration to ground water, a CFV of 10 was assigned (see Sections 2.2.2 and 3.1.1 of this HRS documentation record)

. S oil boring s have shown that the source has no liner, maintained engineered cover, functioning and maintained run

- on control system, runoff management system, or functioning leachate collection and removal system . A grou nd water release of hazardous constituents from unknown sources is documented based on analytical results for ground water samples collected from the source 10 Ref s . 1, Section 3.1.2.1, Table 3

- 2, p. 51596 ; 6, pp. 42

- 49 ; Table 2 of this documentation recor d

Release through Overland Migration and/or Flood Not Scored NA Notes: CFV

- Containment Factor Value HRS

- Hazard Ranking System NA

- Not applicable22 2.4.2 HAZARDOUS WASTE QUANTITY

2.4.2.1 Source Hazardous Waste Quantity

2.4.2.1.1 Hazardous Constituent Quantity (Tier A) The available information is not sufficient to adequately evaluate Tier A as required in Section 2.4.2.1.1 of the HRS. As a result, the evaluation of Hazardous Waste Quantity proceeds to the evaluation of Tier B, hazardous waste stream quantity (Ref. 1, Section 2.4.2.1.1, pp. 51590

- 51591).

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.2 Hazardous Waste s tream Quantity (Tier B) The available information is not sufficient to adequately evaluate Tier B as required in Section 2. 4.2.1.2 of the HRS. As a result, the evaluation of Hazardous Waste Quantity proceeds to the evaluation of Tier C, volume (Ref. 1, Section 2.4.2.1.2, p. 51591).

Hazardous Constituent Quantity Assigned Value: NS

2.4.2.1.3 Volume (Tier C)

Because there is documentation of contamination, but the lateral and vertical extent of the ground water plume have not been adequately characterized, the volume for the ground water plume is designated as unknown but greater than zero (Tier C) (Ref. 1, Section 2.4.2.1.3, Table 2

- 5 , p. 51591).

Volume Assigned Value: >0

2.4.2.1.4 Area (Tier D)
The area ( T ier D) cannot be evaluated (Ref. 1, p. 51591).

Area Assigned Value: 0

2.4.2.2 Calculation of Source Hazardous Waste Quantity Factor Value
As described in the HRS, the h ighest value assigned to a source from among the four tiers of hazardous constituent quantity (Tier A), hazardous waste stream quantity (Tier B), volume (Tier C), or area (Tier D) shall be selected as the source hazardous waste quantity value (Ref. 1, Sect ion 2.4.2.1.5 , p. 51591). Table 4 below summarizes the hazardous waste quantity values.23 TABLE 4 HAZARDOUS WASTE QUANTITY VALUES

Tier Measure Source Value Tier A, Hazardous Constituent Quantity NS Tier B, Hazardous Waste s tream Quantity NS Tier C, Volum e >0 Tier D, Area 0

Table 5 below summarizes the source description.

TABLE 5 SOURCE DESCRIPTION SUMMARY

Source

No. Source Hazardous Waste Quantity

Value Source Hazardous Constituent

Quantity Complete? CFV by Pathway Ground Water Surface Water Air
(Ref. 1, Table 3

- 2) Overland/ Flood (Ref. 1, Table 4

- 2) Ground Water to Surface Water (Ref. 1, Table 3

- 2) Gas (Ref. 1, Table 6

- 3) Particulate (Table 6

- 9)

1 Unknown, but >0 No 10 Not scored Not scored Not scored Not scored

Note: CFV

- Containment Fa ctor Value
Description of Other Possible Sources : Historical Releases of Chlorinated Solvents from Other Possible Operations : Historical releases of chlorinated solvents are possible from the operations discussed below.

Wampler Buick/GMC at 507 and 515 N . Elm Street): Ohio EPA identified t wo po ssible source areas of the VOC contamination (Ref. 6 , p. 6) : the Wampler Buick/GMC facility and the Hobart

- Lytle Road landfill (Ref. 6 , p. 6). The Hobart

- Lytle Road Landfill is discussed further in the “Attributio n” section of this HRS documentation record. The Ohio EPA collected direct

- push ground water samples in and around the Wampler Buick/GMC location in 1997 (Ref. 5, p. 6). Findings from a combined PA/SI confirmed that the West Troy A quifer and the West W ell F ield are contaminated with VOCs and found that the Wampler Buick/GMC facility is a possible source o f the PCE in Troy production well 12W (Ref. 5, p. 15). PCE has not been detected in ground water upgradient from these properties (Ref. 6, p. 6).

The E SI focuse d on 507 and 515 N. Elm Street on the east side of N. Elm Street just north of the C ity of Troy corporation limits (Ref. 6, p. 5). Ohio EPA’s contractor, Tetra Tech, advanced 11 direct

- push24 borings at the properties to approximately 44 feet bgs ( Ref. 6, p. 8). Three water samples were collected from 10 of the 11 borings at the following approximate depths: 20 to 24, 32 to 36, and 40 to 44 feet bgs (Ref. 6, p. 8). Two water samples also were collected from GP

- 86B at 32 to 36 and 40 to 44 feet bgs (Ref. 6, p. 8). The highest concentrations of PCE were found in borings GP

- 84 (41 μ g/ L ) at 20 to 24 feet bgs and GP

- 86B (32 μ g/ L ) at 32 to 36 feet bgs (Ref. 6, p. 8). A s part of the ESI, Tetra Tech installed five monitoring wells (OEPA

- 14, OEPA

- 15, OEPA

- 16, OEPA

- 17, and OEPA

- 18) at 507 and 515 N. Elm Street (Ref. 6, p. 10). The well locations and the screened intervals were based on the direct

- push sampling results , with the goal of verifying the previous detections of PCE and establishing background

co ncentrations (Ref. 6, p. 10). T he five new monitoring wells, two upgradient monitoring wells owned by the C ity of Troy, two existing monitoring wells at 515 N. Elm Street, and city production wells 4W and 12W were sampled (Ref. 6, p. 10). The highest con centration of PCE was found in monitoring well OEPA

- 17 at 21 μ g/ L (Ref. 6, p. 10). PCE was found in city well 12W at 5.7 μ g/ L (Ref. 6, p. 10). The pattern of detections from this and past investigations suggests that a release of PCE may have occurred in the vicinity of the former Wampler Buick/GMC facility at 507 and 515 N. Elm Street in Troy (Ref. 6, p. 12).

Troy Filler Metals Operation : The Troy Filler Metals Operation at 101 Trade Square East is located west of the Wampler Buick/GMC properties and PW

- 12W and has a history of solvent use , including use of chlorinated compounds (Ref. 8, p. 1 7 ). The Troy Filler Metals Operation manufactures welding and soldering equipment and is a Resource Conservation and Recovery Act ( RCRA ) large

- quantity generator (L QG) (Ref. 8, p. 1 2 ). Waste codes F002, F003 , and F005 , which include chlorinated solvents , are documented in biennial RCRA reports for multiple years of operation (Ref. 8, p. 11). The Troy Filler Metals Operation is approximately 3 , 000 feet west

- northwes t of PW

- 12W (Ref. 8, pp. 11 , 12). There are ground water data gaps for the areas west of the Wampler Buick/GMC properties and along and on both sides of Morgan’s Ditch. A ground water sample collected south of Morgan’s Ditch in 1997 contained PCE , and th is finding may indicate a source located west of the Wampler Buick/GMC properties (Ref. 8,
p p . 16 , 17 ; 8A , pp. 19, 20, 25, 36, 72, 73 ). The Troy Filler Metals Operation is upgradient of PW

- 12W (Ref. 8, p. 12).

Additional Po ssible Sources:

A total 108 po ssible sources are identified in the Source Water Assessment and Protection Program Update (SWAP) (Ref

. 9, p. 31)

. The 108 facilities described in the SWAP were identified 

### using three methods (Ref. 9, p. 26). First, local, state, and national, and proprie tary environmental databases were searched for the area encompassed by the SWAP boundary (Ref. 9, p. 26). Aerial25 photographs and parcel maps from the Miami County Auditor were used to help locate the facilities identified in the environmental databases and to ascertain whether any changes in ownership or land use occurred since the database entry was recorded (Ref. 9, p. 26). Once the facilities from the environmental databases were located, a windshield survey was conducted to confirm the location, existen ce, and ownership of the facilities and to locate any other facilities not identified in the environmental databases (Ref. 9, p. 26). Finally, historical aerial photos and USGS quadrangle maps were evaluated to identify changes in historical land use and t o aid in the identification of the historical facility locations (Ref. 9, p. 26).

Regional ground water flow is south following the Great Miami River valley (Ref. 8, p. 1 6 ). Based on this regional flow o ut of 108 possible sources identified in SWAP approx imately 9 possible sources are potentially upgradient of the City of Troy west well field ( Ref. 9, p

. 135). Out of 9 facilities, two facilities located at 507 North Elm Street and 515 North Elm Street are already described in this documentation record (Wa mpler Buick/GMC) ; PCE, TCE and cis

- 1,2 DCE were not detected at one facility (Hobart Brothers Lagoon); one facility located at 542 North Elm Street does not appear to have used PCE, TCE or cis

- 1,2 DCE; the remaining five facilities are summarized below as possible sources [there is no known analytical information available to conclusively identify or refute any of these facilities as a source(s)] :

1. T h e Re

- store: The Re

- store is located at 500 North Elm Street, in Troy, Ohio. The Re

- store sells used furnitu re, appliances, and building materials (Ref. 9, p. 87). A Budget truck trailer, and moving equipment rental business is also operated from the facility . Fleet vehicles are stored and maintained at this location (Ref. 9, p. 87). The property formerly hou sed the Paint Strippers of Troy Company (Ref. 9, p. 87). Potential contaminants at this location include automotive wastes, fluids, lubricants, paints, paint thinners, lacquers, varnishes and other painting chemicals (Ref. 9, p. 87). The SWAP facility ID and location is provided in Reference 9, pages 113 and 135. The SWAP facility ID for T h e Re

- store is 99 (Ref. 9, p. 113). This facility is located northwest of the municipal well 12W (Ref. 9, p. 135).

2. Webster’s Auto : Webster’s Auto repair is lo cated at 525 North Elm Street, Troy, Ohio (Ref. 9, p. 90) . Webster Auto is an automotive service center and collision repair shop (Ref. 9, p. 90) . Several plastic drums were observed in the rear of the property (Ref. 9, p. 90). Potential contaminants from the fa cility include solvents, paints, and automotive waste oils, fluids, and lubricants (Ref. 9, p. 90 ). The SWAP facility ID and location is provided in Reference 9,26 pages 113 and 135. The SWAP facility ID for Webster Auto is 103 (Ref. 9, p. 113). This faci lity is located northwest of the municipal well 12W (Ref. 9, p. 135).

3. Miami County Garage : Miami County Garage is located at 670 Harrison Street, Troy, Ohio (Ref. 9, p. 90) . The Miami County Board of Commissioners operates a garage at this location for m aintaining county vehicles (Ref. 9, p. 90) . The property historically contained underground storage tanks ( USTs ) both at the west end of the garage and the east end of the garage near the Miami County Engineer’s Office (Ref. 9, p. 90) . The type, number, an d contents of the USTs are not reported (Ref. 9, p. 90) . Suspected or confirmed releases occurred at the property with no further action being granted by Bureau of Underground Storage Tank Regulations for both ends of the facility (Ref. 9, pp. 90, 91)

. Po tential contaminants from the facility include gasoline, diesel, kerosene, solvents, paints, automotive waste oils, fluids, and lubricants (Ref. 9, p. 91)

. The SWAP facility ID and location is provided in Reference 9, pages 113 and 135. The SWAP facility ID for Miami County Garage is 104 (Ref. 9, p. 113). This facility is located northwest of the municipal well 12W (Ref. 9, p. 135). G round water samples were collected from six soil borings around the Miami County Garage (Ref. 8A, pp. 10, 17, 19). PCE w as detected at concentrations of 1. 9 μg/L to 6 μg/L in three ground water samples collected from two boring locations (Ref. 8A, pp, 17, 19, 25)

.

4. Former Trojan Specialties : Former Trojan Specialties is located at 745 Harrison Street, Troy , Ohio (Ref. 9, p. 91)

. A vacant commercial building is present at this location (Ref. 9, p. 91)

. Previously , Trojan S pecialties was present at this location (Ref. 9, p. 91)

. While there appears to be no current usage of the building, the potential exists for contaminants associate d with historical usage of the building . This facility is not listed in any environmental database (Ref. 9, p. 91)

. The SWAP facility ID and location is provided in Reference 9, pages 113 and 135. The SWAP facility ID for Form e r Trojan Specialties is 105 (Ref. 9, p. 113). This facility is located northwest of the municipal well 12W (Ref. 9, p. 135).

5. Action Tire Auto Center : Action Tire and Auto Center is located at 816 Harrison Street, Troy, Ohio (Ref. 9, p. 91). Action Tire and Auto Center is a tire shop and automotive servi ce
center (Ref. 9, p. 91)

. The property historically contained one or more USTs; however, the type, number, and contents of the USTs are not reported (Ref. 9, p. 91)

. The USTs have been removed and no further action status has been granted to the facilit y (Ref. 9, p. 91)

. The facility is also listed under OEPA’s underground injection control database , which indicates27 the presence of a heating/cooling well, storm runoff wells/drains, a septic system, motor vehicle disposal wells/drains, or other types of wells or drains used to direct fluids below ground (Ref. 9, pp. 91, 92)

. An above ground storage tank ( AST ) was observed in the rear of the property. The AST had no underlying secondary containment (Ref. 9, p. 92)

. Potential contaminants from the locati on include gasoline, diesel, solvents, automotive waste oils, fluids, and lubricants (Ref. 9, p. 92)

. The SWAP facility ID and location is provided in Reference 9, pages 113 and 135. The SWAP facility ID for Action Tire Auto Center is 106 (Ref. 9, p. 113 ). This facility is located northwest of the municipal well 12W (Ref. 9, p. 135).

3.0 GROUND WATER MIGRATION PATHWAY Geology and Hydrogeology

The Great Miami River overlies an extensive aquifer system composed of unconsolidated Pleistocene and Holocene se diments that partially fill a previously eroded valley carved into the underlying bedrock (Ref s . 6, p. 7 ; 11, p. 18 ). Generally, the geology of the area consists of near

- surface, presumably river

derived silt, sand, and gravel deposits underlain by glacia l deposits of sand and gravel interbedded with till (Ref s . 6, p. 7 , 39, 41 ; 11, pp. 17, 18, 20, 21 ). In some areas , these outwash deposits are separated by glacial tills and lacustrine deposits (Ref s . 9, p. 1895 ; 11, pp. 17, 20, 21 ). Traditionally , the G reat Miami River valley has been called a two

- aquifer system (Ref. 6, p. 7) . H owever, because there is little evidence for a single, laterally extensive till unit separating two sand and gravel aquifers across the entire valley, it is best described as a single

- aquifer system (Ref s . 6, p. 7 ; 11, pp. 17, 18, 20, 21 ). The lower aquifer is semi

- confined, and there is hydraulic communication between the shallow and deep aquifers through gaps in the confining unit and leakage across the confining unit (Ref s

. 9 , p. 1895 ; 11, pp. 17, 18, 20, 21 ). In the area of the City of Troy ’s w ell field s , the productive portion of the buried valley aquifer is composed of thick sequences of glacial outwash deposits (unconsolidated san d s, gravels, silts , and clays) (Ref s

. 6,
p p. 39, 41; 9, p. 1895 ; 11, pp. 17, 18, 20, 21 ).

Leakance studies of the river bed conducted by Troy’s wellhead protection consultant have shown that the river discharges to the aquifer in the reach of the w ell field (Ref s . 6, p. 7; 11, p. 1 9 ). This is p robably due

to the influence of the production wells and suggests that the recharge of the deeper sand and gravel deposits in which the city wells are screened is induced by ground water drawdown caused by pumping (Ref s . 6, p. 7; 11, p. 19). The bedrock d eposits that compose the buried valley walls are relatively impermeable compared to the sand and gravel aquifers (Ref s . 11, p. 19 ). Water wells in the bedrock deposits generally yield less than 10 gpm (Ref s . 11 , p. 19 ).28 Aquifer Interconnection

Hydraulic c ommunication between the two aquifers generally is either directly through gaps in the confining unit ( which is absent in some parts of the buried valley) or through leakage through the confining unit (Ref. 1 1 , p. 18). In order to better understand surfac e and ground water interactions at the well fields, the riverbed hydraulic characteristics of the Great Miami River were investigated. This investigation revealed ground water flow to the river north of the West Well Field and surface water flow from the river to the ground water system adjacent to and south of both well fields. These findings suggest that recharge of the aquifers from the river is induced by ground water drawdown caused by pumping (Ref. 1 1 , p. 19). The Panterra Corporation r eport includ es a geologic cross section of the area (Ref s . 1 1 , pp. 20 , 21).

Two aquifer pump tests were conducted during the supplemental ESI to evaluate interconnectivity between the Wampler Buick/GMC wells on the west side of the Great Miami River and PW

- 12W on the east side (Ref s . 8 , p. 5 ; 9 a , pp, 1 ). The first pump test was conducted during the first week of June 2010 (Ref. 8 , p. 5). All West Well Field production wells were turned off for approximately 24 hours before pumping began at PW

- 12W in order to stress the aquifer (Ref. 8 , p. 5). Water level reading s were collected continuously during this time using pressure transducers (Ref s . 8 , p. 5 ; 9b; 9c; 9d; 9e , p. 1 ). A significant rainfall event occurred about midway through the pump test , causing potential bi as in the results (Ref. 8 , p. 5). Because the first pump test was potentially compromised by the rainfall event and river level changes, a second pump test was conducted between August 30 and September 2, 2010 (Ref s

. 8 , p. 5 ; 9 a , p p .1 , 2, 33

- 43 ). Product ion wells were sampled during this pump test in the same manner as during the first pump test (Ref. 8 , p. 6). There is an obvious response in the observation wells [located at the former Wampler Buick/GMC property] when well 12W was pumping. Water levels in all four wells dropped at the start of the two tests and started immediately recovering at the end of the tests (Ref s . 9, pp. 1895

- 1896 ; 9a, pp, 1, 35

- 38, 41 ). The Ohio EPA DDAGW staff evaluated pump test results and concluded that hydraulic communicat ion exists between the shallow sands and gravels on the west side of the Great Miami River and the deeper sands and gravels on the east side of the river where PW

- 12W is located (Ref s . 8, p. 1 5 ; 9 a , p p . 1 , 9b; 9c; 9d; 9e , p.1 ). Pump tests conducted at C ity of Troy well PW

- 15 in the E ast W ell F ield in 1994 and at both well fields in 2000 demonstrate communication between shallow and deep sand and gravel deposits and indicate that the capture zone of the well field s extends across the river (Ref. 8 , p. 1 3 )

. Therefore, the hydraulic interconnection between the upper and lower aquifer is well established and the lower and upper aquifer system is referred to as an unconsolidated aquifer.29 Aquifer Discontinuity

As detailed on Table 6 below, the combined upper a nd lower aquifers were evaluated as one unconsolidated aquifer system

. The Great Miami River does not entirely transect the upper aquifer. The geologic cross section of the Great Miami River on Figure 4 of the Panterra Corporation report shows that the G reat Miami River does not entirely transect the upper aquifer at the West Troy Contaminated Aquifer (Ref. 11, pp. 20 , 21 )

. Figure 3 of the Panterra Corporation report shows the location of the cross section relative to the land surface (Ref. 11, p. 17 ).

Figure 4 of the Panterra Corporation report shows a cross section running north to south in the vicinity of the West Troy Contaminated Aquifer (Ref. 11, pp. 20 , 21 )

. The plume and the City of Troy We st Well Field are located near well 1 2W (see Figure 3 o f Reference 1 1 for well locations and Figure 1 of this HRS documentation record for the general site location) , and the site is nearest to the northern location of the cross section . The cross section shows that at the point where the cross section cross es Great Miami River, the upper aquifer is approximately 40 feet thick and the river depth (including the river valley) is shown as only 10 feet. Therefore , based on this cross section , the river does not entirely transect the upper or combined aquifer s

.

Based on a ctual field measurements of the depth of the Greater Miami River at a U.S. Geological Survey (USGS) gauging station in the City of Troy o n several dates from 2005 through 2007, the Great Miami River depth ranged from 1. 4 0 to 10.40 feet deep at t he station (Ref. 12, p. 3)

. This range of river depth, when compared to the thickness of the upper aquifer of 10 to 40 feet in the vicinity of the plume , supports the conclusion discussed above that the Great Miami River does not entirely transect either the upper or combined upper and lower aquifers. Table 6 below summarizes the aquifer characteristics.

TABLE 6 AQUIFER CHARACTERISTICS SUMMARY

Source No. Aquifer Type Is Aquifer Continuous Within

- 4

- Mile Target Distance Limit? Is Aquifer Karst?
1 Unconsol idated Yes No

3.1 LIKELIHOOD OF RELEASE

3.1.1 Observed Release Aquifer Being Evaluated: Unconsolidated a quifer system ( interconnected upper and lower sand and gravel aquifer s )30 Direct Observation : An observed release by direct observation to the ground w ater migration pathway has not been established at the West Troy Contaminated Aquifer.

Chemical Analysis: Establishing an observed release through chemical analysis requires analytical evidence of a hazardous substance in a medium at a concentration sig nificantly exceeding the background concentration. If the background concentration of a chemical is not detected (or is less than the detection limit), an observed release is established when a sample measurement equals or exceeds its own sample quantitat ion limit (SQL) and the background SQL . If the SQL cannot be established, the EPA contract

- required quantitation limit (CRQL) should be used instead of the SQL (Ref. 1, Section 2.3, p. 51589).

Background Levels :

- Background Level at Source 1

– Other

-- Co ntaminant Plume

Regional ground water flow is south following the Great Miami River valley (Ref. 8, p. 1 6 ). Ground

water at Troy is part of the Great Miami River Buried Valley Aquifer System (Ref s

. 8, p. 1 6 ; 9, pp. 128 , 129). Based on available ground wa ter flow information , monitoring wells MW

- C, MW

- E and MW

K are considered to be a background (upgradient) wells. Figure 3 shows the background sampl ing locations. The contaminants of concern for the West Troy Contaminated Aquifer (PCE; TCE; and cis

1,2

- D CE) were not detected in ground water samples collected from the background monitoring well locations (Ref. 9, pp. 1602, 1603, 1722, 1723, 1725, 1726, 1728, 1729, 1731, 1732, 1734, 1735, 1737, 1738, 1861, 1862). The a bsence of contaminants of concern in the ground water samples suggests that the background locations to the depth of approximately 140 feet bgs lie outside the area of contamination.

Table 7 below summarizes background location information and the concentrations of contaminants of concern d etected in ground water samples collected from each location.31 TABLE 7 BACKGROUND LOCATION AND CONCENTRATION INFORMATION

Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval or

Screen Length

(feet) Sample No. Sampling Date Hazardous Substance Concentratio n Detected (μg/L) CRQL (μg/L) References

MW

- E_S UC 25 15

- 125 E2509 7/19/2010 PCE 0.5 U 0.5 Ref s . 6, p. 5 1 ; 9 , pp. 1001, 1554, 1662

- 1669,1674, 1675, 1727

- 1729, 1787, 1930, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- E_I UC 7 0 15

- 125 E2508 7/19/2010 PCE 0.5 U 0.5 Ref s . 6, p. 5 1 ; 9, pp. 1001, 1554, 1662

- 1669,1674, 1675, 1730

- 1732, 1787, 1929, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- E_D UC 122 15

- 125 E2507 7/19/2010 PCE 0.5 U 0.5 Ref s . 6, p. 5 1 ; 9, pp. 1001, 1504

- 1512,1517, 1518, 1554 1602

- 1605 , 1787, 1931; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- K_S UC 35 140 E2512 7/19/2010 PCE 0.5 U 0.5 Ref s . 9, pp. 898, 1554, 1787, 1820

- 1825, 1826, 1827, 1844, 1861

- 1863, 1 917, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- K_I UC 75 140 E2511 7/19/2010 PCE 0.5 U 0.5 Ref s . 9, pp. 898, 1554, 1662

- 1669,1676, 1677, 1721

- 1723, 1787, 1916, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.5

MW

- K_D UC 121 140 E2510 7/19/2010 PCE 0.5 U 0.5 Ref s . 9, pp. 898, 1554, 1662

- 1669,1676, 1677, 1724

- 1726, 1787, 1926, 1949; 10, pp. 1 , 2 TCE 0.5 U 0.5 cis

- 1,2

- DCE 0.5 U 0.532 Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval or

Screen Length

(feet) Sample No. Sampling Date Hazardous Substance Concentratio n Detected (μg/L) CRQL (μg/L) References

MW

- C_S UC 25 15

- 61 E2506 7/19/2010 PCE 0. 5 U 0.5 Re f s . 6, p. 50; 9, pp. 1001, 1662

- 1669,1674, 1675, 1733

- 1735, 1788, 1927, 1949; 10, pp. 1 , 2 TCE 0. 5 U 0.5 cis

- 1,2

- DCE 0. 5 U 0.5

MW

- C_D UC 50 15

- 61 E2505 7/19/2010 PCE 0. 5 U 0.5 Ref s . 6, p. 50; 9, pp. 1001, 1662

- 1669,1674, 1675, 1736

- 173 8, 1788, 1928, 1949 ; 10, pp. 1 , 2 TCE 0. 5 U 0.5

c is

- 1,2

- DCE 0

. 5 U 0.5

Notes: μg/L

– Microgram per liter bgs

– Below ground surface CRQL

– Contract

- Required Quantitation Limit (Ref. 10, pp. 1 and 2) DCE

- Dichloroethene PCE

– Tet rachloroethene TCE

– Trichloroethene NA

– Not Available U

– Analyte was analyzed for but was not detected above the reported sample quantitation limit (Ref. 9, pp. 1512, 1669, and 1825) UC

– Uncon solidated aquifer

Contaminated Samples :

- Contaminated Sample s at Source 1

– Contaminated Plume

Table 8 below summarizes t he results for ground water samples contaminated with PCE collected from monitoring wells and public supply wells at the West Troy Contaminated Aquifer . Figure 3 of this HRS documentation record show s the sampling locations.

TABLE 8 CONTAMINATED SAMPLE INFORMATION

Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) References

OEPA

- 14 UC 44 39

- 44 E2495 7/21/10 PCE 8.7 0.5 Refs. 6, p. 45; 9, pp. 1000,33 Location No. Aquifer Well or Sampling

Depth (feet bgs) Well Screen Interval

(feet) Sample No. Sampling Date Hazardous Substance Concentration Detected (μg/L) CRQL (μg/L) References

1504

- 1512, 1579, 1785, 1905; 10, pp. 1 , 2 OEPA

- 16 UC 25 15

- 25 E2497 7/21/10 10 0.5 Refs. 6, p. 47; 9, pp. 1000, 1504

- 1512, 1585, 1785, 1907; 10, pp. 1 , 2 OEPA

- 17 UC 34 29

- 34 E2498 7/21/10 18 0.5 Refs. 6, p. 48; 9, pp. 1000, 1504

- 1512, 1588, 1785, 1932; 10, pp. 1 , 2 PW

- 12W UC 86 66

- 86 E2500 7/21/10 5.2 0.5 Refs. 6, pp. 38

- 39; 9, pp. 1504

- 1512, 1591, 1785, 1911; 10, pp. 1 , 2

W

- 3 UC 33.20 NA E2518 7/22/10 7.1 0.5 Ref s . 9, pp. 150 4

- 1512, 1519

- 1520, 1556, 1923; 10, pp. 1 , 2 W

- 8 UC 16.59 7.6

- 17.5 E2522 7/22/10 3.9 0.5 Ref s . 9, pp. 1001, 1504

- 1512, 1557, 1631, 1921; 10, pp. 12 W

- OB UC 34.45 NA E2521 7/22/10 6.5 0.5 Ref s . 9, pp. 1504

- 1512, 1557, 1628, 1919; 10, pp. 1 , 2 RW

- 5 UC NA NA E2529 7/21/10 9.1 0.5 Ref s . 9, pp. 1820

- 1825, 1845, 1875, 1900; 10, pp. 1 , 2 PW

- 12W UC 86 66

- 86 E2500 7/21/10 TCE 0.81 0.5 Refs. 6, pp.38, 39; 9, pp. 1504

- 1512 ,1591 1785, 1911; 10, pp.1, 2

PW

- 12W UC 86 66

- 86 E2500 7/21/10 Cis

- 1,2

- DCE 1. 1 0.5 Refs. 6, pp.38, 39; 9 , pp. 1504

- 1512, 1590, 1785, 1911;10, pp.1, 234 Notes: μg/L

– Microgram per liter bgs

– Below ground surface CRQL

– Contract

- Required Quantitation Limit (Ref. 10, pp. 1 and 2) DCE

- Dichloroethene PCE

– Tetrachloroethene TCE

- Trichloroethene NA

– Not Available U

– Analyte was analyzed for but was not detected above the reported sample quantitation limit (Ref. 9, pp. 1512, 1669, and 1825) UC

– Uncon solidated aquifer
The background and downgradient monitoring well samples were collected within the same timeframe (between July 19 and 22, 2010) (Ref. 9, pp. 1904

- 1937). The samples were collected with peristaltic and bladder pump s using a low

- flow sampling technique (Ref. 9, pp. 1904

- 1937). The ground water samples were col lected after the following field parameters had stabilized: pH, conductivity, dissolved oxygen (DO), temperature, oxidation

- reduction potential , and turbidity (Ref. 9, pp. 1904

- 1937). The samples were analyzed by the U.S. EPA CLP) for VOCs using same meth od (Ref. 9, pp. 1504

- 1512).

The ground water samples from private and public wells collected on July 21, 2010 , are considered in this HRS documentation record (Ref. 9, pp. 1908

- 1912). The samples were collected on the same day by the same sampler (Ref. 9 , pp. 1908

- 1912). The samples were analyzed by the U.S. EPA CLP for VOCs (Ref. 9, pp. 1504

- 1512 , 1820

- 1825).

West Troy Contaminated Aquifer Plume Releases (Contaminated Plume):

The West Troy Contaminated Aquifer plume has received releases from unidenti fied source(s). Releases associated with the plume area were detected through chemical analysis of ground water samples collected from residential, monitoring, and municipal wells. Analytical results for ground water samples collected from the plume area document observed releases to ground water, primarily of PCE; TCE; and cis

- 1,2

- DCE (see Table 2 , Contaminated Sample Information). As discussed in Section 3.1.1 above, if the background concentration of a chemical is not detected (or is less than the det ection limit), an observed release is established when a sample measurement equals or exceeds its own SQL and the background sample concentration. If the SQL cannot be established, the EPA CRQL should be used instead of the SQL (Ref. 1, Section 2.3, p. 51 589). VOCs were not detected in background wells, so all detected VOC concentrations exceeding the SQL qualify as observed release

.

Attribution :
The West Troy Contaminated Aquifer ground water plume includes PCE from unidentified source(s). The plume als o contains TCE and cis

- 1,2

- DCE, which are biodegradation products of PCE (Ref. 13, pp.35 2 , 5) . PCE; cis

- 1,2

- DCE; and TCE do not exist naturally and are manmade chemicals (Ref s

. 20 , p. 2; 21,
p. 1; 22, p. 1; 23, p. 1) . Significant ground water sampling ha s been performed to identify sources of the PCE contamination, but no sources have yet been conclusively identified. During the PA/SI , the Ohio EPA advanced four direct

- push soil borings

. Ground water samples were collected from 4 monitoring wells at the Earhart Petroleum property , 4 monitoring wells at the Hobart Lagoon, 6 city monitoring wells, and 11 monitoring wells at the Wampler Buick/GMC facility (Ref. 6, p. 6). Troy production wells 4W and 12W also were sampled (Ref. 5, p. 7). PCE was detected i n ground water samples from the Wampler Buick/GMC location (Ref. 5, pp. 8, 12, and 13). PCE was also detected in Troy production well 12W (Ref. 5, pp. 8, 13). The combined PA/SI identified the Wampler Buick/GMC property as a possible source of the PCE in Troy production well 12W (Ref. 5, p. 15).

The ESI focused on the two properties at 507 and 515 N. Elm Street located on the east side of N. Elm Street just north of the C ity of Troy corporation limits (Ref. 6, p. 5). The properties are approximately 650 feet west of the Great Miami River and 1⁄4 mile northwest of well 12W (Ref. 6, p. 5). The property at 507 N. Elm Street contains a building used by an automobile repair business (Ref. 6, p. 5). The property at 515 N. Elm Street contains one building origi nally a drive

- in restaurant and presently used as an office for a used

- car dealership (Ref. 6, p. 5). Both properties are mostly covered with asphalt or gravel except for areas beneath the buildings (Ref. 6, p. 5). Ohio EPA’s contractor, Tetra Tech, adva nced 11 direct

push borings at the properties to approximately 44 feet bgs (Ref. 6, p. 8). T hree water samples were collected from 10 of the 11 borings at the following approximate depths: 20 to 24, 32 to 36, and 40 to 44 feet bgs (Ref. 6, p. 8). Two wat er samples also were collected from GP

- 86B at 32 to 36 and 40 to 44 feet bgs (Ref. 6, p. 8). PCE was detected at several depths in ground water samples collected from 10 soil boring locations, (Ref. 6, pp. 8 and 9). As part of the ESI, Tetra Tech install ed five monitoring wells

. T he five new monitoring wells, two upgradient monitoring wells owned by the C ity of Troy, two existing monitoring wells at 515 N. Elm Street, and city production wells 4W and 12W were sampled (Ref. 6, p. 10). PCE was detected in samples from seven monitoring wells and public supply well 12W (Ref. 6, pp. 18, 19, 30, 32, 34). The pattern of detections from this and past investigations suggests that a release of PCE has occurred in the vicinity of the former Wampler Buick/GMC locat ion at 507 and 515 N. Elm Street in Troy (Ref. 6, p. 12). A n actual source of PCE contamination was not determined during the ESI.

During Phase I of the supplemental ESI , five public wells in the W est W ell F ield were sampled before and after the pump te st (Ref. 8, p. 5). During Phase 2 of the supplemental ESI , 5 W est Well Field production wells, 24 monitoring wells , and 5 private production wells were sampled (Ref. 8, p. 6 ). Ground water sampling results confirm ed that West Well Field wells PW

- 12W and PW

- 3W are contaminated with VOCs (Ref. 8, p. 16). PCE was detected at concentrations exceeding its MCL in PW

-36 12W. TCE, DCE , and TCA were detected in PW

- 12W at concentrations below their respective MCLs (Ref. 8, p. 1 6 ). DCE was detected in PW

- 3W for the first time in supplemental ESI samples, but all detections were below the DCE MCL (Ref. 8, p. 1 7 ). TCA was detected in samples from two private production wells (non

- potable) on the west side of the Great Miami River (Ref. 8, p. 1 7 ). Sample s from monitor ing wells at the Wampler Buick/GMC properties contained VOCs at concentrations similar to those detected in 2005. The highest detection of PCE was 18 μg/ L in OEPA

- 17 (Ref. 9 , p. 1941 ). Ohio EPA DDAGW staff evaluated pump test results and concluded that hydraulic communication exists between the shallow sands and gravels on the west side of the Great Miami Ri ver and the deeper sands and gravels on the east side of the river where PW

- 12W is located (Ref s . 6, p p

. 7, 1 1 ; 8, pp. 14 , 16 ). The Wampler Buick/GMC properties could not be confirmed as the actual source of contamination (Ref. 8, p.
1 7 ). No source area was identified because of the lack of definitive information on which to base source area soil sampling (Ref. 8, p. 1 7 ). The City of Troy minimized pumping PW

- 12W and blended water from both well fields to reduce VOC concentrations to below detectable lim its in finished water (Ref. 8, p. 1 7 ).

Soil samples collected in 1999 by ITW

- Hobart at the Hobart

- Lytle Road landfill, located about 4,600 feet northwest of the West Troy Contaminated Aquifer plume , were found to be contaminated with solvents, including T CE. Soil samples collected at the landfill in 2000 had detections of PCE and TCE ( Ref. 5, p.
7 ). Ground water samples taken by Ohio EPA in 2001 from a property south and east of the landfill showed contamination with benzene, ethyl benzene and xylene, but not PCE, TCE or 1,2

- cis DCE ( Ref. 5, p. 7 ). Therefore, at this time , the Hobart

- Lytle Road landfill is not considered as a possible source for the ground water contamination in the plume

. Based on the investigation s performed on several potential source areas , the ground water contamination source cannot be identified or reasonably attributed with confidence. Because the source is a contaminated ground water plume with no positively identified source of contamination, no separate attribution is required (Ref. 1, Section 3.1.1, p. 51595).

Hazardous Substances Released:

The following hazardous substances are present in the observed release :

• P CE

• TCE

• c is

- 1,2

- DCE Ground Water Observed Release Factor Value: 55037 3.1.2 Potential to Release As specified in t he HRS, because an observed release has been established for the aquifer, the potential to release is not scored (Ref. 1, Section 3.1.2, p. 51595).

3.2 WASTE CHARACTERISTICS

The primary hazardous substance in the ground water plume impacting the City of T roy W est W ell F ield is PCE . The contamination is described as a ground water plume with no identified source. PCE w as detected in several wells at concentrations exceeding the background levels . Ground water samples collected from municipal well PW

- 12W have been shown to be impacted by PCE , TCE and DCE ( Ref s

. 6, pp. 6, 11 ; 5, p p. 5, 13 ). The released substances are believed to be from an unknown source or sources

we st

- northwest of the municipal wells.

3.2.1 Toxicity/Mobility

All hazardous substances liste d in Table 9 below are documented in ground water samples collected from the West Troy Contaminated Aquifer. These hazardous substances were detected at concentrations significantly exceeding background levels. TABLE 9 OBSERVED RELEASE AND TOXICITY/MOBIL ITY SUMMARY

Hazardous Substance Toxicity Factor Value Mobility Factor Value Does Hazardous Substance Meet Observed Release Criteria? Toxicity/ Mobility Reference

PCE 100 1 Yes 100 Ref s . 1, Sections 3.2.1.1, 3.2.1.2, and 3.2.1.3, pp. 51601 , 51602; 2, p p

. A

- A

2, 336 , TCE 100 0 1 Yes 10 00

cis 1,2

- DCE 100 0 1 Yes 100 0 Ref s . 1, Sections 3.2.1.1, 3.2.1.2, and 3.2.1.3, pp. 51601 ,, 51602; 2, p. A

- 134 Notes: DCE

– Dichloroethene PCE

– Tetrachloroethene TCE

- Trichloroethene
Because an observed release to the gr ound water migration pathway has been established, a mobility factor of 1 is applied to the hazardous substances released (Ref. 1, Section 3.2.1.2, p. 51601). As shown in Table 9 above, the toxicity/mobility factor value for T CE is 100 0 . The Toxicity/Mob ility Factor Value of 100 0 is assigned based on Table 3

- 9 of the HRS (Ref. 1, Section 3.2.1.3, p. 51602).38 Toxicity/Mobility Factor Value: 100 0

3.2.2 Hazardous Waste Quantity

Table 10 below summarizes the hazardous waste quantity information for the West Tr oy Contaminated Aquifer.

TABLE 10 HAZARDOUS WASTE QUANTITY SUMMARY

Source No. Source Name Source Type Source Hazardous Waste Quantity 1 Ground Water Plume Other Unknown but > 0

The West Troy Contaminated Aquifer has been scored as a contaminated groun d water plume with no identified source. According to Section 2.4.2.2 in the HRS (Ref. 1, p. 51592), if any target sample for the migration pathway is subject to Level I or Level II concentrations and the hazardous constituent quantity is not adequately d etermined, the Hazardous Waste Quantity Factor Value for that pathway should either be assigned the value from Table 2

- 6 (Ref. 1, p. 51591) or a value of 100, whichever is greater. Because Level I concentrations were detected in samples from a drinking wa ter well (see Section 3.3.2.2 of this HRS documentation record ), a Hazardous Waste Quantity Factor Value of 100 is assigned to the ground water pathway.

Hazardous Waste Quantity Factor Value: 100 (Ref. 1, Section 2.4.2.2, p. 51592)

3.2.3 Waste Characteris tics Factor Category Value As specified in the HRS (Ref. 1, Section 3.2.3, p. 51602), the Hazardous Waste Quantity Factor Value of 100 is multiplied by the highest Toxicity/Mobility Factor Value of 1 , 0 0 0 , resulting in a product of 10 0 ,000 (1.0E+0 5 ). Based on this product, a Waste Characteristics Factor Category Value of 1 8 is assigned from Table 2

- 7 of the HRS (Ref. 1, Section 2.4.3.1, p. 51592). The highest Toxicity/Mobility Factor Value of the substances listed in Section 3.2.1 of this HRS documentation record is for TCE and cis

- 1,2

- DCE

. Toxicity/Mobility Factor Value: 100 0 Hazardous Waste Quantity Factor Value: 10039 Toxicity/Mobility Factor Value (100 0 ) × Hazardous Waste Quantity Factor Value (100) =
10 , 000 = 1 × 10 5

Waste Characteristics Facto r Cate gory Value: 1 8 (Ref. 1, Table 2

- 7 , p. 51592 )

3.3 TARGETS

A total of 10 municipal wells are located within the 4

- mile

- radius Target Distance Limit (TDL) from the

c enter of the plume (Ref s . 14, p. 1; 15, p. 1; 16, p. 1). The 4

- mile

- radius TDL is shown in Reference 2 8

. The primary municipal well of concern is operated by the City of Troy municipal water system (Ref. 6,
p p

. 5 , 6 ). One municipal well (PW

- 12W) operated by the City of Troy is within the W est T roy Contaminated Aquifer and is impacted by the ha zardous substances of concern (Tables 7 and 8 )

. The targets evaluated for the ground water migration pathway are summarized below.

Level I Concentrations

Level I concentrations have been documented in one City of Troy public supply well (PW

- 12W ) shown in Table 11 below.

TABLE 11 LEVEL I CONCENTRATIONS

Sample ID Hazardous Substance Hazardous Substance Concentration (μg/L) Benchmark Concentration (μg/L) Benchmark References for Benchmark E2 500 (PW 12W ) PCE 5.2 1.6 Cancer Risk Screening Concentration Ref. 2, p. A

336

Notes: See Table 8 for concentrations detected in th e drinking water well samples. μg/L = Microgram per liter ID

- Identification PCE

– Tetrachloroethene

3.3.1 Nearest Well

Well ID: PW

- 12W Level of Contamination (I, II, or potential): Level I40 B ecause actual contamination at Level I concentrations has been documented, a nearest well factor value of 50 is assigned (Ref. 1, Section 3.3.1, Table 3

- 11, p. 51603).

Nearest Well Factor Value: 50 (Ref. 1, Table 3

- 11, p. 51603)

3.3.2 Population 3.3.2.1 Leve l of Contamination The City of Troy municipal system has approximately 10,600 service connections and supplies to the City of West Milton and Miami County P ublic W ater S ystem (PWS) (Ref. 1 7 , p

. 2 ). The 10,600 City of Troy service connections include one service connection to the City of West Milton and one service connection

to the Miami County PWS (Ref. 17, p. 2 )

. The City of West Milton has approximately 2, 066 service connections , and the Miami Co unty PWS has approximately 1, 4 42 service connections (Ref s . 1 9 , p. 1 ; 2 4 , p. 1) . Therefore, the total number of service connections served by City of Troy w ater system is 14, 10 6 (10,600

- 2 + 2, 066 + 1, 4 42 ). According to the U.S. Census Bureau, there are approximately 2. 52 persons per household in Miami County , Ohio (Ref. 18 , p. 1 ). Therefore, the total estimated population served by the City of Troy water system is 35, 547 ( 14, 1 0 6 total service connections × 2. 52 persons per household for Miami C ounty). The City of Troy water system has 10 municipal wells (Ref. 17 , p. 1 ). The water pumped from these wells is blended (Ref. 17, p. 1 ). Between October 2010 and August 2011 , PW

- 1 2W has been out of service due to contamination (Ref s . 1 7, p. 1 ; 17a, p.1 ). Ho wever, PW

- 12W was put back in service in August 2011 because OEPA was concerned that without this well running at least at a reduced flow, the contamination noted in that well might be drawn into other wells (Ref. 17a, p. 1).

T he City of Troy Water Depa rtment provided t he annual pumping rate for each municipal well for 20 1 0 (Ref. 16, p

. 2). Based on these data, Table 1 2 below summarizes the annual pumping rates (Ref. 16 , p. 2 ) :

TABLE 1 2 ANNUAL MUNICIPAL WELL PUMPING RATES

Well ID Annual Pumpage 2010, M illion Gallons Percentage Pumpage (%)
3W 184.2 13 .1 4W 107.3 7.6 16 145 10 .3 12W 10.7 0.841 19 119.5 8 .5 14 129.7 9 .2 18 147.1 10

. 4 4E 222.6 1 5.8 13 154.1 1 0.9 17 189.9 13 .5 Total 1410.1 100 .1 1 Note: 1

– Total exceeds 100 percent due to rounding Source: Ref s

. 1 6 , p.2; 26, p. 1 ID

- Identification
Based on the annual pumping rates for 20 1 0, no municipal well supplied more than 40 percent of the system’s total water. Therefore, the population of 35,547 is apportioned equally to each municipal well (Ref. 1, Section 3.3.2, p. 51603; Ref. 24 , pp. 1). Based on this approach, the population served by each well is approximately 3,5 54 (35, 547 divided by 10 municipal wells).

3.3.2.2 Level I Concentrations

Level I Population Targets

For municipal well PW

- 12W , the population allocated is 3,5 54

. Contamination of the Level I well is documented in Tables 2 and 8 . Table 1 3 summarizes the Level I population affected by PW

- 12W , which is completed in the unconsolidated aquifer (Ref. 17 , p. 3 )

.

TABLE 1 3 LEVEL I POPULATION

Level I Well Aquifer Population Reference

PW

- 12W Uncon solidated 3,5 54 Ref. 1, Section 3.3.2.2, p. 51603

Sum of Population Served by Level I Wells: 3,5 54 Sum of Population Served by Level I Wells × 10 = 35, 540 (Ref. 1, Section 3.3.2.2, p. 51 603).

Level I Concentrations Factor Value: 35, 54 0

3.3.2.3 Level II Concentrations Level II Population Targets42 Based on the HRS (Ref. 1, Section 3.3.2. 3 , p. 51603), no targets are subject to Level II contamination.

Level II Concentrations Factor Value: 0.

3.3.2.4 Potential Contamination

Because Level I concentrations provide the maximum score for the ground water migration pathway, the potential contamination factor is not scored for this HRS documentation record. Although potential contamination is not scored, there is a concern about populations that could be exposed to contaminated drinking water.

Potential Contamination Factor Value: Not Scored

3.3.3 RESOURCES

Ground water within the 4

- mile

- radius TDL is used for commercial food preparation (Ref. 1 7 , p. 3 ). Therefore, the Resources Factor is assigned a value of 5 (Ref. 1, Section 3.3.3, p. 51604).

Resources Factor Value: 5

3.3.4 WELLHEAD PROTECTION AREA The wellhead protection area factor is not scored because it does not impact the overall score

.

Wellhead Protection Area Factor Value: 0

3.3.5 CALCULATION OF TARGET S FACTOR CATEGORY VALUE The total target factor category value is the sum of the nearest well, population, resources, and wellhead protection area values (Ref. 1, Section 3.3.5, p. 516 04). The total target factor category value for the site is 50 (nearest well) + 3 5 , 540 (population) + 5 (resources) + 0 (wellhead protection area) = 3 5 , 5 95

.