### HRS DOCUMENTATION RECORD COVER SHEET

Name of Site: Compass Plaza Well TCE

EPA ID No.: MON000706143

Contact Persons

EPA Contact: Michelle Quick U.S. Environmental Protection Agency, Region 7

901 North 5th Street Kansas City, Kansas 66101 (913) 551-7335

Site Investigation: Pia Capell and Michael Stroh, Missouri Department of Natural Resources (MDNR) Hazardous Waste Program, Site Assessment Unit

Documentation Record: David Zimmermann, Tetra Tech START

Pathways, Components, or Threats Not Scored

The surface water migration, soil exposure, and air mi gration pathways were not scored in this Hazard Ranking System (HRS) evaluation. No releases or impacts to surface water and/or air migration pathway were identified by previous investigations. These mi gration pathways do not contribute significantly to the overall site score. The soil exposure pathway was not evaluated because no significant areas of soil

contamination were documented in the top two feet of soil and no contamination was documented on the property of a residence and within 200 feet of the resi dence. Therefore, this exposure pathway would not be expected to contribute to the overall site score.

### HRS DOCUMENTATION RECORD

Name of Site: Compass Plaza Well TCE

EPA Region: 7

Date Prepared: September 2011

Street Address of Site*: 201 South Marshall Street

City, County, State, Zip Code: Rogersv ille, Greene County, Missouri 65742

General Location in the State: The City of Rogersville is located in southwest Missouri, 8.4 miles east of Springfield, Missouri on U.S. Highway 60.

Topographic Map: United States Geological Survey. Rogersville, Missouri quadrangle: 7.5-Minute Series Topographic Map, N3700-W9300/7.5. 1970.

Latitude: 37.109009° North

Longitude: 93.083168° West

The latitude and longitude listed above specify the approximate center of the ground water plume associated with Compass Plaza Well TCE. Google Earth ( www.google.com/earth/index.html ) was used to obtain the coordinates (Ref. 21). Figure 1 s hows the location of Compass Plaza Well TCE.

Scores

Ground Water Migration Pathway 100 Surface Water Migration Pathway Not scored Soil Exposure Pathway Not scored Air Migration Pathway Not scored

HRS SITE SCORE 50.00

*The street address, coordinates, and contaminant locatio ns presented in this HRS documentation record identify the general area the site is located. They represent one or mo re locations EPA considers part of the site based on the screening information EPA used to evaluate the site fo r NPL listing. EPA lists national priorities among the known

“releases or threatened releases” of h azardous substances; thus, the focus is on the release, not precisely delineated

boundaries. A site is defined as where a hazardous substa nce has been “deposited, stored, placed, or otherwise come to be located.” Generally, HRS scoring and the subseq uent listing of a release merely represent the initial determination that a certain area may need to be addres sed under 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 contamination has come to be located.



### September 2011 1

### September 2011 2

### HRS SITE SCORE

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 NA

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

2c. Surface Water Migration Pathway Score (S

sw 

### ) Enter the larger of lines 2a and 2b as the pathway score. NS NA

3. Soil Exposure Pathway Score (S

s 

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

4. Air Migration Pathway Score (S

a 

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

5. Total of S gw 2 

### + S

sw 2 

### + S

s 2 

### + S

a 2 

### 100 10,000

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

Notes:

NS Not Scored NA Not Applicable

September 2011 3

### September 2011 4 HRS TABLE 3-1 — GROUND WATER MIGRATION PATHWAY SCORESHEET

COMPASS PLAZA WELL TCE

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 x (2b + 2c + 2d)] 500 NS 3. Likelihood of Release (higher of lines 1 and 2e) 550 550

Waste Characteristics: 4. Toxicity/Mobility a 10,000 5. Hazardous Waste Quantity a 100

6. Waste Characteristics 100 32 Targets:

7. Nearest Well 50 50 8. Population:

8a. Level I Concentrations b 580

8b. Level II Concentrations b 0

8c. Potential Contamination b 101 8d. Population (lines 8a + 8b + 8c) b 681

9. Resources 5 0

10. Wellhead Protection Area 20 5 11. Targets (lines 7 + 8d + 9 + 10) b 736 GROUND WATER MIGRATION SOURCE FOR AN AQUIFER 12. Aquifer Source [(lines 3 x 6 x 11)/82,500] c 

### 100 100

GROUND WATER MIGRATION PATHWAY SCORE 13. Pathway Score (S gw 

### ), (highest value from line 12 for all aquifers evaluated) c 

### 100 100

a 

### Maximum value applies to waste characteristics category.

b 

### Maximum value not applicable.

c 

### Do not round to nearest integer.

NS Not Scored

### REFERENCES

Reference

Number Description of the Reference

1 U.S. Environmental Protection Agency (EPA). Hazard Ranking System, 40 CFR Part 300, Appendix A, 55 FR 51533. December 14, 1990. Entire rule can be found on the World

Wide Web at http://www.epa.gov/superfund/sites/npl/hrsres/#HRS%20Rule Excerpt. 1

page.

2 EPA. Superfund Chemical Data Matrix. Interi m revised values for trichloroethene (TCE), Appendix A, BI and BII and Table BI for other compounds. Accessed online at: http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm Revised October 23, 2006 (for TCE), other compounds January 27, 2004. Excerpt. 14 pages.

3 United States Geological Survey. Rogersv ille, Missouri quadrangle: 7.5-Minute Series Topographic Map, N3700-W9300/7.5. 1970. Location of the center of the ground water plume added by Tetra Tech. 1 sheet.

4 Capell, Pia and Michael Stroh. Missouri Department of Natural Resources. Site Inspection/Removal Site Evaluation Report for the Compass Plaza TCE Well Site, Greene County, Missouri. EPA ID Number MON00070 6143. February 1, 2011. 1,570 pages.

5 Capell, Pia. Missouri Department of Natural Resources. Abbreviated Preliminary

Assessment Checklist for the Compass Plaza TCE Well Site, Greene and Webster Counties, Missouri. EPA ID Number MON000706143. March 25, 2010. 6 pages.

6 Jacobs Engineering Group, Draft Site Inspection Prioritization Positronics Industries site. EPA contract number; 68-W8-0122, work assignment number 53-7WZZ. January 1994. 67 pages.

7 EPA. Envirofacts Warehouse-CERCLIS Query. On-line address: http://iaspub.epa.gov/enviro/cerclis _web.report?pgm_sys_id=MOD007447196 . Accessed March 29, 2011. 2 pages.

8 Bachle, Peter. Geological Survey Program, Division of Geology and Land Survey.

Memorandum- Geohydrologic Summary of Compass Plaza Well Site. April 15, 2010. 30 Pages.

9 Hughes, Harold E. U.S. Department of Agriculture, Soil Conservation Service. Soil Survey Of Greene and Lawrence Counties, Missouri. March 1982. Five excerpted pages.

10 Web Soil Survey Map for Compass Plaza TCE Well site. From U.S. Department of Agriculture, Natural Resource Conservation Service online mapping tool found at: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx . Map created January 13, 2011. Three pages.

11 Miller, Don E. and James E. Vandike. Miss ouri Department of Natural Resources’ Division of Geology and Land Survey. Missouri State Water Plan Series Volume II

Groundwater Resources of Missouri. Water Resources Report Number 46. 1997. 24 excerpted pages.

12 State of Missouri Division of Geological Survey and Water Resources. Well Log for City of Rogersville Well Number 2 , Log No. 27997. Logged in September 1976. Well log

obtained on-line from: http://www.dnr.mo.gov/env/wrc/logmain/greene.pdf Four pages.

13 Tetra Tech EM, Inc. (Tetra Tech). Quality Assurance Project Plan for Removal Action at the Compass Plaza TCE site . Contract No. EP-S7-06-01, Task Order No. 0194. August 13, 2010. 17 pages.

September 2011 5

### Reference Number Description of the Reference

14 Scroggin, Tom (TS), Tetra Tech START, a nd Doug Ferguson, EPA Region 7 Superfund Emergency Response and Removal (SUPR/ER&R). Chain of Custody Forms, Field Sheets and Logbook for Compass Plaza Well TCE Removal Action Support. For Analytical Services Request (ASR) number 5049 for sampling event from August 16 - 25, 2010. 31

pages.

15 Davis, Michael F., Chief, Chemical Analysis and Response Branch, Environmental Services Division, U.S. Environmental Protection Agency Region 7 to Doug Ferguson, EPA Region 7 Superfund Emergency R esponse and Removal (SUPR/ER&R). Transmittal of Sample Analysis Results for ASR #5049 for the Compass Plaza Well TCE sampling. September 16, 2010. 18 pages.

16 EPA Region 7. HRS Analysis Results Supplement for ASR #5049 for the Compass Plaza Well TCE sampling. January 7, 2011. 34 pages.

17 Ellis, Harry V. III, PhD, Tetra Tech, to Tetra Tech Project file. Review and Validation of the Missouri Department of Natural Res ources (MDNR) Data and Sample Quantitation

Limit. Memorandum. February 14, 2011. 24 pages.

18 Sims, Judith L. and others. Superfund Technology Support Center for Ground Water. Reductive Dehalogenation of Organic Contamin ants in Soils and Groundwater. Office of Solid Waste and Emergency Response. EPA/540/4-90/054. January 1991. 12 pages.

19 Ferguson, Doug, EPA Region 7 Superfu nd Emergency Response and Removal (SUPR/ER&R). Chain of Custody Forms and Field Sheets for Compass Plaza Well TCE Removal Action Support. For Analytical Services Request (ASR) number 5255 for sampling event from February 22 - 24, 2011. 37 pages.

20 Missouri Department of Natural Resources. Source Water Assessment Plan Maps and well information for the Rogersville PWSS No. 5010699 . Prepared by the Center for Applied Research and Environmental Systems, Univers ity of Missouri. Map update May 14, 2010. 4 pages.

21 Zimmermann, David, Tetra Tech Project Mana ger. Project Note Regarding the Latitude and Longitude for the Compass Plaza TCE Well site (CERCLIS ID Number: MON000706143). July 25, 2011. 1 page.

22 Missouri Department of Natural Resources, Public Drinking Water Program. Drinking

Water Source Water Assessment Plan . Plan accessed online at http://drinkingwater.missouri.edu/swap/ on May 19, 2011. 2 pages (excerpt).

23 Missouri Department of Natural Resources, Division of Geology and Land Survey. High Yield and Public Well Record and Pump Info rmation Data form for well with reference number of 00331792. February 18, 2004. 1 page.

24 Missouri Department of Natural Resources, Division of Geology and Land Survey. Water Well Certification and Pump In formation Record form for well with reference number of 279327. October 12, 2001. 1 page.

25 Missouri Department of Natural Resources, Division of Geology and Land Survey. Domestic/Multifamily Well Record and Pump Information Data form for well with

reference number of 00421957 identifie d as the Jamestown Irrigation well. August 25, 2009. 1 page.

26 Missouri Department of Natural Resources. Source Water Assessment Plan Maps and well information for Bill’s Quick Mart Well #1 PWSS No. 5258130 . Prepared by the Center for Applied Research and Environmental Systems, University of Missouri. Map update April 7, 2011. 3 pages.

September 2011 6

### September 2011 7 Reference Number Description of the Reference

27 Missouri Department of Natural Resources, Division of Geology and Land Survey (DNR DGLS). Missouri Sample Well-Log Libr ary for well with Log Number of 025206. October 1967. 2 pages.

28 Missouri Department of Natural Resources, Division of Geology and Land Survey (DNR DGLS). Missouri Sample Well-Log Libr ary for well with Log Number of 029048. April 22, 2004. 1 page.

29 Missouri Department of Natural Resources, Division of Geology and Land Survey (DNR DGLS). Missouri Sample Well-Log Libr ary for well with Log Number of 014464. May 3, 1956. 2 pages.

30 Missouri Department of Natural Resources, Division of Geology and Land Survey. High Yield and Public Well Record and Pump Info rmation Data form for well with reference number of 00251660. July 3, 2000. 1 page.

31 Scroggin, Tom. Tetra Tech START Project Ma nager. Project Memorandum Regarding the Records Search for the Compass Plaza TCE Well site (CERCLIS ID Number: MON000706143). July 18, 2011. 1 page.

32 U.S. Census Bureau. American FactFinder. Rogersville City, Missouri, Table QT-P11,

Households and Families: 2010 , 2010 Census Summary File 1. Accessed on line at: http://factfinder2.census.gov/faces/tableservi ces/jsf/pages/productview.xhtml?pid=DEC_10 _SF1_QTP11&prodType=table . Accessed August 12, 2011. 2 pages.

33 Logan-Rogersville R-VIII School District. Buildings in our District. Document accessed

online at: http://www.logrog.net/MiscPaperWork/BuildingsINourDISTRICT.htm

. Accessed July 15, 2011. 1 page.

34 Tetra Tech EM, Inc. (Tetra Tech). Addendum #1 to the Quality Assurance Project Plan for Removal Support at the Compass Plaza TCE site . Contract No. EP-S7-06-01, Task Order No. 0194. February 24, 2011. 18 pages.

35 Scroggin, Tom (TS), Tetra Tech START, a nd Doug Ferguson, EPA Region 7 Superfund Emergency Response and Removal (SUPR/ER&R). Chain of Custody Forms and Field Sheets for Compass Plaza Well TCE Removal Support. For Analytical Services Request (ASR) number 5367 for sampling event from May 10 – 12, 2011. 79 pages.

36 Davis, Michael F., Chief, Chemical Analysis and Response Branch, Environmental Services Division, U.S. Environmental Protection Agency Region 7 to Doug Ferguson, Superfund Emergency Response and Removal North Branch (SUPR/ERNB). Transmittal of Sample Analysis Results for ASR #5367 for the Compass Plaza Well TCE sampling. June 10, 2011. 46 pages.

37 Missouri Department of Natural Resources, Division of Geology and Land Survey (DNR DGLS). Missouri Sample Well-Log Libr ary for well with Log Number of 012589. March 1954. 2 pages.

38 State of Missouri Division of Geological Survey and Water Resources. Well Log for City of Rogersville Well Number 1 , Log No. 12589. Logged in January 1954. Well log

obtained on-line from: http://www.dnr.mo.gov/env/wrc/logmain/greene.pdf . 4 pages.

39 EPA Region 7. Analysis Information: ASR 4907 . May 10, 2010. 4 pages.

### SITE DESCRIPTION

Compass Plaza Well TCE is located in southeaster n Greene County near the Webster and Christian County borders. The approximate center of the gr ound water plume which encompasses the site is

1.4 miles north of the border of Greene and Christian Counties and 1 mile west of the Greene and Webster County border (see Figure 1). The contaminated ground water plume is on the west side of Rogersville, Missouri. Rogersville is located in Gr eene and Webster counties. The site consists of contaminated ground water that has impacted domestic and irrigation wells. The primary contaminant of concern in ground water is trichloroethene (TCE) (Ref . 4, pp. 4, 5) although other chlorinated solvents have been reported in grou nd water samples in addition to TCE (Ref. 4, p. 8). The Compass Plaza Strip

mall is located at 201 South Marshall Street on th e western edge Rogersville, Missouri. An initial detection of TCE was found in the drinking water well that serves Compass Plaza on June 18, 2009 (Ref. 5, p. 1). Consequently, additional sampling wa s conducted of eight public water wells in the area (Ref. 5, p. 1). Of these, two had detections of TC E: one which supplies the Citizen’s Bank of Rogersville and another that provides irrigation water (Ref. 5, p. 1).

The Compass Plaza Well TCE site is a ground water plume in Greene County near Compass Plaza, a commercial area on the city of Rogersville’s wester n edge. Following routine public drinking water monitoring in June 2009, TCE was detected in the Co mpass Plaza strip mall well at levels below the EPA Maximum Contaminant Level (MCL) for drinking wate r. Two nearby wells were sampled and also showed the presence of TCE below the MCL. The s ite was referred by the MDNR’s Public Drinking Water Branch (PDWB) to the Hazardous Waste Pr ogram (HWP) in March 2010 for further assessment under CERCLA (Ref. 4, p. 4).

The site was discovered and entered into CERCLIS on March 24, 2010 (Ref. 4, p. 4). An Abbreviated Preliminary Assessment (APA) was completed on Ma rch 25, 2010 (Ref. 5, p. 1). The site was

recommended for further CERCLA assessment to iden tify the source of the TCE and further evaluate exposure (Ref. 5, p. 5). A site inspection/remova l site evaluation (SI/RSE) was initiated by MDNR on April 1, 2010 and included multiple sampling events (R ef. 4, pp. 4, 5, 25, 26). By mid June, 2010, the State had sampled 121 wells and 13 contained TCE; six of these we lls had TCE at concentrations exceeding the EPA MCL (Ref. 4, pp 1538, 1539). Also as part of the SI, the state conducted a search for possible sources of the ground water contamination and collected soil samples from suspect areas (Ref. 4, pp. 9 – 17). No source of the TCE in ground water w as identified (Ref. 4, p. 17). A removal action was initiated by EPA on August 10, 2010, an d is ongoing (Ref. 4, p. 4). Th e general objective of the removal action is to eliminate, through the provision of a permanent alternative water supply or whole-house filtration, human exposure of TCE and/or other h azardous substances present in ground water (Ref. 4, p. 1557).

The site lies on the eastern border of the Springfield Plateau of the Ozark Plateau sub-province of the Interior Highlands physiographic province in Missouri. This area is characterized by rolling upland hills with low relief (Ref. 8, p. 1). Based on topographic maps, there are many sinkholes near the site. There are also 14 known springs near the site. Based upon this information and the limestone bedrock that underlies the site and comprises the uppermost aquifer, the site lies within a karst area (Refs. 4, p. 19; 8, p. 5).

September 2011 8 Site Description

### After contamination was identified in ground water west of Rogersville, staff from the State of Missouri’s Southwest Regional Office (SWRO), the U.S. Environmental Protection Agency (EPA), and Missouri Department of Natural Resources (MDNR) Hazardous Waste Program (HWP) met on July 7, 2010 to review historical file information and potential s ource area locations reported to staff from various entities in the Rogersville area (citizens, public works employees, city office staff) (Ref. 4, p. 9). As shown on Figures 2 and 3 of the SI/RSE report, five potential areas for investigation were identified; two north of highway 60 (Compass Plaza Cleaners & Laundromat and Positronics Inc.), and three south of highway 60 (a former woody debris burn pile area, a residen tial property at the location of a TCE-contaminated private well, and an industrial area east of Rogersville that is served by three private wells (Ref. 4, pp. 9, 42, 43). A sampling event was conducted on July 27-28, 2010, and documented in a Site Inspection Sampling Report (Ref. 4, pp. 9, 1160). All samples during the investigation were analyzed for volatile organic compounds (VOC) (Ref. 4, p. 1165). Duri ng the MDNR SI/RSE soil samples were collected from the former Compass Cleaners & Laundromat which operated at the Compass Plaza strip mall from approximately 2004 to 2007 (Ref. 4, pp. 10, 42). Subsurface soil samples were collected near a solvent tank, and between the solvent tank and contaminated we ll at Compass Plaza (Ref. 4, pp. 10, 42). At the Positronics Inc, location, which is east of the Comp ass Plaza well, soil samples were collected from four borings located near a former lagoon and from an i rrigation field where process waste water containing chlorinated solvents were once sprayed (Refs. 4, pp. 10, 11, 42; 6, pp. 4, 13, 18). At the former woody debris burn pile area, soil samples were collected from three boring located in an area where tree debris was burned following a 2007 ice storm (Ref. 4, pp. 12 , 43). At the residential property were TCE was found at high concentrations in the private well (well 176), three soil borings were advanced in areas near sinkholes to determine if they may be a source for contamination (Ref. 4, pp. 12, 13, 43). MDNR sampled three private ground water wells east Rogersv ille located in an area used by various commercial businesses (Ref. 4, pp. 13, 14, 42). The wells were sampled to determine if ground water contamination exists east of Rogersville that woul d warrant additional investigation.

Of the five areas investigated, subsurface soil near the Compass Plaza Cleaners & Laundromat was shown to contain low concentrations (estimated) of tetrachlo roethene (PCE) (Ref. 4, pp. 15, 16). Soil at the former Positronics Inc. facility and the former burn ar ea contained low concentrations of non-chlorinated volatile organic compounds (VOC) (Ref. 4, pp 15, 16) , and all other sample collected to characterize possible areas of contamination did not contain any chlorinated volatile organic compounds (Ref. 4, pp. 15 – 18).

In December 2010, EPA investigated allegations of illegal dumping of spent solvents on a property around the Rogersville area (Ref. 31) . Webster and Greene Counties’ deeds records dating back to 1960 were searched to determine whether the person alle gedly responsible for dumping solvents ever owned property in the Rogersville area. No records matc hing the name of the pers on in the allegation were found (Ref. 31).

As part of ongoing support to the EPA Region 7 removal program, in May 2011 Tetra Tech START collected additional soil and ground water samples to identify potential source areas and further delineate impacted private drinking water wells (Refs. 34, pp.8, 11, 13; 35; 36, p. 3). Thirty-four soil samples were proposed to be collected at multiple depths in and ar ound sinkholes, in a drainage feature, at the former Compass Plaza Laundromat, and at the former Positronics facility (Ref. 34, p. 13). Thirty soil samples were actually collected and submitted for VOC analysis from 13 soil borings (Refs. 35, pp. 1 – 30; 36, pp. 3, 5). The only chlorinated VOC detected in soils was tetrachloroethene (PCE) at a concentration of 30 micrograms per kilogram ( μ g/kg) in sample 5367-4 (Ref. 36, pp. 8 – 23). This sample was collected from a depth of 6 to 7 feet below ground surface at the former Compass Plaza Laundromat (Ref. 35, p. 4). No TCE or cis-1,2-DCE were reported in soil sample 5367-4 (Ref. 36 , pp. 8, 9). No other soil sample contained detected levels of any chlorinated vola tile organic compound (Ref. 36, pp. 2, 3, 8 – 23).

September 2011 9 Site DescriptionSource Number: 1



### Investigations conducted to date have not identified the source of the TCE found in ground water. Therefore, this site will be scored as a gr ound water plume with no identified source.

2.2 SOURCE CHARACTERIZATION

2.2.1 SOURCE IDENTIFICATION

Name of source: Ground Water Plume (with no identified source)

Number of source: 1

Source Type: Other (Ground Water Plume)

Description and Location of Source (with reference to a map of the site): Figure 2

Source 1 is a ground water plume located on the west side of Rogersville, Missouri. The well that serves the Compass Plaza is located behind the buildings in Compass Plaza and is located most closely to the former Compass Cleaners and Laundromat (Ref. 4, pp. 5, 41, 44, 48). The well, constructed in 2004, has a total depth of 750 feet and draws water from the Ozar k Aquifer (Refs. 4, p. 7; 23). Prior to the summer of 2009, the Compass Plaza well was considered a non- community transient water supply (Ref. 4, p. 7). In the spring of 2009, the Graceland Daycare c onnected to the Compass Plaza well which changed the

status of the well from a transient to a non-transi ent water supply (Ref. 4, p. 7). A non-transient noncommunity well is defined as a public water system that is not a community water system that regularly serves at least 25 of the same persons over 6 months per year (Ref. 4, p. 7). Non-transient noncommunity wells are required to conduct periodic chemi cal testing. The first such testing was conducted by the MDNR’s Public Drinking Water Branch (PDWB) on June 18, 2009 (Ref. 4, pp. 7, 62, 160). TCE was detected 3.73 micrograms per liter ( μ g/L) (Ref. 4, pp. 7, 62, 63). Seven public drinking water wells located nearest the site were sampled on a number of occasions between March and July 2010 (Ref. 4, p. 25). The samples collected by the PDWB documented TCE contamination in a well serving the Citizen’s Bank of Rogersville and an irrigati on well referred to as the Jamestown Irrigation well (Ref. 4, pp. 7, 28, 41). These wells are shown in Figures 1 and 5 of the SI/RSE report (Ref. 4, pp. 41, 45).

Following the initial detection of TCE in the Comp ass Plaza public well in June 2009, successive rounds of sampling were conducted by MDNR beginning with wells nearest Compass Plaza and extending outward (Ref. 4, p. 25). After several rounds of sampling public wells, the site was referred to the Hazardous Waste Program (HWP) in March 2010 fo r further assessment under CERCLA (Ref. 4, pp. 4, 7). Ground water sampling by the HWP included public and private drinking water wells (Ref. 4, pp. 25, 26). Sampling plans prepared for the domestic well sampling events are provided in the appendix of the SI/RSE report (Ref. 4, pp. 1499-1505, 1514-1524, 1538-1543). Ground water samples collected by MDNR were analyzed by the state’s environmen tal laboratory within the Environmental Services Program (ESP) by EPA Safe Drinking Water Act Me thod 524.2 for VOCs (Ref. 4, pp. 26, 1503).

Private wells located near the site were identifie d using well records from MDNR Division of Geology and Land Survey (DGLS) databases. Additional we lls were added to the sampling program based on requests by private residents following a public meeti ng held in Rogersville on May 25, 2010. In all, access was gained to 121 private drinking water we lls, and these were sampled over the period between March and September of 2010 (Ref. 4, p. 26). The list of sampled private wells and the designated code for each well sampled by the HWP is included in Table C1 of the SI/RSE report (Ref. 4, pp. 26, 57 -59). Figure 5 of the SI/RSE report shows all public and pr ivate well sampling locations (Ref. 4, p. 45).

September 2011 10 Source CharacterizationSource Number: 1



### September 2011 11 Source Characterization During initial rounds of sampling, samples were colle cted only from outside taps nearest the wellhead. Subsequent rounds of sampling also included sample coll ection at an inside tap (typically the kitchen). Duplicate samples were collected, and trip blanks pr ocessed as specified in the Quality Assurance Project Plan (QAPP) (Ref. 4, p. 26). All samples were s ubmitted to the MDNR’s ESP laboratory for analysis of VOCs by EPA drinking water method 524.2 (Ref. 4, p. 26). The analytical data were validated by Tetra Tech (Ref. 17).

In the summer of 2010, MDNR requested that EPA Region 7 to provide alternative water supply to households drinking contaminated ground water (R ef. 4, p. 1557-1558). EPA Region 7 tasked the START contractor to provide removal assessment s upport by resampling State identified contaminated wells and also perform post filtration sampling at we lls where whole house filtration systems were to be installed (Ref. 13, pp. 5, 11, 13). Samples were collected on August 16 and 17, 2010 and post filtration samples were collected on August 25, 2010 (Ref .14) . EPA sampled the same wells that the MDNR HWP had previously sampled where TCE contaminati on had been found. In addition one new well was sampled at a residence that was not previously sampled by the state (Ref.14, p. 17). This well contained TCE and will be referred to by the sample number which is 5049-15 (Ref. 15, p. 13).

Ground water wells sampled by MDNR PDWB and HWP and by EPA Region 7 that have been shown to be contaminated by TCE are shown on Fi gure 2 of this documentation record.Source Number: 1September 201112Source CharacterizationSource Number: 1



### 2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THIS SOURCE

The table below presents all the ground water wells at th e site that have been documented to contain one or more chlorinated VOCs at a concentration signifi cantly above background concentration as established by HRS rule, Table 2-3 (Ref. 1, Section 2.3 a nd Table 2-3). Further discussion of the general characteristics of the aquifer is presented in Section 3.0.1 of this documentation record. What is known about the depths of the contaminated wells and the presentation of background well information is provided in Section 3.1.1 of this documentation record. The location of the wells presented below is shown on Figure 2.

GROUND WATER CONCENTRATIONS

Sample ID Sample Designation Sample

Date Hazardous Substance Hazardous Substance
Concentration (μg/L) Sample Quantitation
Limit** (μg/L) References

AB15892 03/08/2010 TCE

cis- 1,2-DCE 3.07

1.07 0.5

0.5 4, pp. 28, 68, 69, 165; 17, p.

1 Compass

Plaza Well AB16170 03/16/2010 TCE

cis- 1,2-DCE 3.84

1.21 0.5

0.5 4, pp. 28, 92, 93, 170; 17, p.

1

AB15915 03/08/2010 TCE

cis- 1,2-DCE 2.25

0.66 0.5

0.5 4, pp. 74, 75, 163; 17, p. 1 Citizen’s

Bank of Rogersville AB16169 03/16/2010 TCE

cis- 1,2-DCE 2.11

0.69 0.5

0.5 4, pp. 90, 91; 17, p. 1

Jamestown Irrigation

well AB16171 03/16/2010 TCE

cis- 1,2-DCE 4.96

1.84 0.5

0.5 4, pp.28, 94, 95, 169; 17, p.

1

1000438 04/15/2010 TCE 1,1,2-TCA 313

0.84 0.5

0.5

1003701 04/22/2010 TCE 1,1,2-TCA 323

0.83 0.5

0.5 4, pp. 29, 57, 198, 199, 550, 551, 604, 605, 618, 619; Ref. 17, p. 1. MDNR 176 a

5049-11 08/17/2010 TCE 180 6.3 14, p.13; 15, pp. 10, 11; 16, p. 18

1000747 04/15/2010 TCE 1.10 0.5

1003692 04/21/2010 TCE 1.33 0.5

1003715 09/13/2010 TCE

cis- 1,2-DCE 1.41

0.5 0.5

0.5 4, pp. 29, 57, 198, 199, 512, 572, 1327, 1377, 1378; Ref. 17, p. 1. MDNR 168 a

5049-3 08/16/2010 TCE 1.1 0.5 14, p.5; 15, pp. 6, 7; 16, p. 5

1000750 04/15/2010 TCE

cis -1,2-DCE 2.27

0.83 0.5

0.5

1003697 04/21/2010 TCE

cis -1,2-DCE 2.32

0.92 0.5

0.5 4, pp. 29, 57,198, 199, 524, 581, 582; Ref. 17, p. 1. MDNR 170 a

5049-5 08/16/2010 TCE

cis -1,2-DCE 1.2

0.58 0.5

0.5 14, p.7; 15, pp. 8, 9; 16, pp. 7, 8

1000689 03/30/2010 TCE

cis -1,2-DCE 5.41

1.91 0.5

0.5

1000720 04/14/2010 TCE

cis -1,2-DCE 5.44

2.03 0.5

0.5 4, pp. 28, 57, 198, 199, 234, 235, 378, 404; Ref. 17, p. 1 MDNR 102 a

5059-18 08/17/2010 TCE

cis -1,2-DCE 5.4

1.8 0.5

0.5 14, p.20; 15, pp. 14, 15; 16, pp. 27 - 29



### September 2011 13 Source CharacterizationSource Number: 1

GROUND WATER CONCENTRATIONS (Continued)

Sample ID Sample Designation Sample

Date Hazardous Substance Hazardous Substance
Concentration (μg/L) Sample Quantitation
Limit** (μg/L) References

1000724 04/14/2010 TCE 0.89 0.5

1003725 09/15/2010 TCE

cis -1,2-DCE 1.26

0.65 0.5

0.5 4, pp. 28, 57, 198, 199, 420, 1366, 1381, 1382; Ref. 17, p. 1 MDNR 104 a

5049-7 08/16/2010 TCE 1.1 J* 0.5 14, p. 9; 15, pp. 5, 8, 9; 16, pp. 10, 11

1003785 03/31/2010 TCE

cis -1,2-DCE 4.79

1.61 0.5

0.5

1000725 04/14/2010 TCE

cis -1,2-DCE 5.19

1.8 0.5

0.5 4, pp. 29, 57, 198, 199, 238, 239, 390, 424; Ref. 17, p. 1 MDNR 118 a

5049-13 08/17/2010 TCE 1.3 0.5 14, p.15; 15, pp. 12, 13; 16, pp. 19 - 21

1003790 03/31/2010 TCE 0.65 0.5

1000730 04/14/2010 TCE 0.97 0.5 4, pp. 29, 57, 198, 199, 236, 237, 342, 444; Ref. 17, p. 1 MDNR 121 a

5049-6 08/16/2010 TCE 0.66 0.5 14, p.8; 15, pp. 8, 9; 16, pp.

8 - 10

1003784 03/30/2010 TCE

cis -1,2-DCE 3.57

1.28 0.5

0.5 MDNR 117 a

1000733 04/14/2010 TCE

cis -1,2-DCE 2.9

1.36 0.5

0.5 4, pp. 28, 57, 198, 199, 238, 239, 386, 456; Ref. 17, p. 1

1003781 03/30/2010 TCE

cis -1,2-DCE 6.36

2.7 0.5

0.5

1000734 04/14/2010 TCE

cis -1,2-DCE 6.74

2.47 0.5

0.5 4, pp. 28, 57, 198, 199, 228, 229, 320, 460; Ref. 17, p. 1 MDNR 114 a

5049-9 08/17/2010 TCE

cis -1,2-DCE 6.2

2.2 0.50

0.50 14, p. 11; 15, pp. 10, 11; 16, pp. 13, 14

1000736 04/14/2010 TCE 0.85 0.5

1003720 09/15/2010 TCE 0.66 0.5 4, pp. 29, 57, 198, 199, 468, 1347, 1379, 1380; Ref. 17, p. 1 MDNR 124 a

5049-8 08/17/2010 TCE 0.74 0.5 14, p. 10; 15, pp. 8, 9; 16, pp. 11 - 13

1003706 04/22/2010 TCE

cis -1,2-DCE 4.14

1.29 0.5

0.5 4, pp. 30, 58, 612, 613, 620, 621; Ref. 17, p. 1 MDNR 181 a

5049-4 08/16/2010 TCE

cis -1,2-DCE 4.5

1.4 0.5

0.5 14, p. 6; 15, pp. 6, 7; 16, pp. 5, 6

1000571 06/15/2010 TCE

cis -1,2-DCE 5.41

3.13 0.5

0.5 4, pp. 30, 58, 641, 687, 688, 783; Ref. 17, p. 1 MDNR 251 a

5049-1 08/16/2010 TCE

cis -1,2-DCE 5.8

2.6 0.5

0.5 14, p. 3; 15, pp. 6, 7; 16, pp. 1, 2

No code EPA sample

5049-15 08/17/2010 TCE

cis -1,2-DCE 4.4

1.6 0.5

0.5 14, p. 17; 15, pp. 12, 13; 16, pp. 22 – 24

Notes:

a Well codes are those used by MDNR

* TCE in this sampled is estimated and the result is biased low due to low recoveries of surrogate analytes (Ref. 15, p. 5) J The identification of the analyte is acceptable; the reported value is an estimate (Ref. 15, p. 2) ** The reporting limits presented in the data packages are equivalent to sample quantitation limits (SQLs) (Ref. 17, p. 1)

DCE Dichloroethene

μ g/L Micrograms per liter

TCA Trichloroethane

TCE Trichloroethene



### September 2011 14 Source Characterization

### 2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Samples collected by MDNR and EPA have show n that contaminants occur in ground water.

Containment Description Containment

Factor

Value Reference

Gas Release to Air: Not scored Not applicable

Particulate Release to Air: Not scored Not Applicable

Release to Ground Water: The contai nment factor value for the ground water migration pathway was evaluated for “A ll Sources” for eviden ce of hazardous substance migration from source area. A pplicable containment factor value was determined based on existing analytical evidence of hazardous substances in ground water samples from public and private wells. Therefore, based on evidence of a release, the highest gro und water migration pathway containment factor value of 10 was assigned as specified in Table 3-2 of the HRS Rule (Ref. 1, Section 3.1.2.1). 10 1, Section 3.1.2.1, Table 3-2;

Release through Overland Migration and/or Flood: Not scored Not Applicable



### 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 information available is not sufficient to evaluate Tier A, as required in Section 2.4.2.1.1 of the HRS Rule. As a result, the evaluation of Hazardous Waste Quantity proceeds to evaluation of Tier B, hazardous wastestream quantity (Ref. 1, Section 2.4.2.1.1).

Hazardous Constituent Quantity Assigned Value: Not Scored

2.4.2.1.2. Hazardous Wastestream Quantity (Tier B)

The information available is not sufficient to evaluate Tier B. As a result, the evaluation of Hazardous Waste Quantity proceeds to evaluation of Tier C, volume (Ref. 1, Section 2.4.2.1.2).

Hazardous Wastestream Quantity Assigned Value: Not Scored

2.4.2.1.3. Volume (Tier C)

For the migration pathways, the source is assigned a value for volume using the appropriate Tier C equation from Table 2-5 (Ref. 1, Section 2.4.2.1.3). As measure by geographical information system (GIS), the approximate lateral extent of the plume is 636 acres. Because the vertical extent of the ground water plume is unknown, the volume for the ground water plume will be designated as unknown, but greater than zero. Volume Assigned Value: > 0

September 2011 15 Source Characterization

### September 2011 16 Source Characterization 2.4.2.1.4 Area (Tier D)

The area measure (Tier D) is not evaluated for source type “other” (Ref. 1, Table 2-5).

Area of source (ft 2 ): Not evaluated Area Assigned Value: Not evaluated



### 2.4.2.1.5. Source Hazardous Waste Quantity Value

As described in the HRS, the highest value assigne d to the source from the four measures of hazardous waste quantity (Tiers A, B, C, and D) is assigned as the source hazardous waste quantity value (Ref. 1, Section 2.4.2.1.5). Thus, the source hazardous wast e quantity value is unknown, but greater than zero.

Source 1 Hazardous Waste Quantity

Tier Measure Source Values
Tier A, Hazardous Constituent Quantity NS Tier B, Hazardous Wastestream Quantity NS Tier C, Volume > 0 Tier D, Area NS

Notes:

> Greater than\

NS Not scored



### Highest assigned value assigned from Table 2-5: > 0; but unknown

SUMMARY OF SOURCE DESCRIPTIONS

Containment Factor Value by Pathway

Surface Water (SW) Air

Source

No. Source

Hazardous

Waste Quantity

Value Source

Hazardous

Constituent

Quantity Complete?

(Yes/No) Ground

Water (GW) (Table 3-2) Overland/Flood (Table 4-2) GW to SW (Table 3-2) Gas (Table 6-3) Particulate (Table 6-9)

1 > 0 No 10 NS NS NS NS

Notes:

> Greater than

NS Not scored



### Description of Other Possible Sources

MDNR and EPA have taken efforts to identify the so urce of the ground water contamination and have not located a definitive source to date. Five potentia l source areas have been identified and sampled; however, no clear source of the ground water contamina tion has been identified (Ref. 4, pp. 17, 18).

One possible source that was samp led was at the Compass Cleaners & Laundromat which operated in the Compass Plaza strip mall from approximately 2004 to 2007 (Ref. 4, pp.10, 42). Initially, dry cleaning

services were subcontracted out to another location (Ref. 4, p.10). In December 2006, the business obtained dry cleaning equipment and provided the ser vice on site (Ref. 4, p.10). An older model drycleaner machine was initially bought but was quick ly traded for a machine that used a petroleum

### solvent-based system (Ref. 4, pp 1484, 1486, 1488) . The solvent tank was lo cated inside the main building (Ref. 4, p.10). According to the former ow ner of the business, solvents used in the first dry cleaning machine were most likely a chlorinated solven t such as PCE (Ref. 4, p. 1488). As part of the SI/RSE activities, two subsurface borings were advanced on the southwest corner of the laundromat building as shown on Figure 2 of the SI/RSE report (Ref. 4, pp. 10, 42). Boring SB04 was located as near to the location of the solvent tank as practical (Ref. 4, pp. 10, 42, 50). Soil samples were collected from this location at 15.5 feet depth (slightly elevated photo ionization detector reading) and from 28 feet (refusal) (Ref. 4, p. 10). A replicate soil sample was coll ected at the 28 foot depth (Ref. 4, p. 10). Boring SB05 was located near the parking lot between the solvent tank and the Compass Plaza public well (Ref. 4, pp. 10, 42, 51). All soil sample s were submitted to the department’s laboratory for analysis of VOCs (Ref. 4, p. 10). Low levels of PCE were reported in soil boring SB04 (Ref. 4, pp. 15, 16, 1212, 1213, 1216, 1217). This area was resampled by EPA in May 2011 (Refs.34, pp.8, 11, 13; 35; 36, p. 3). The only chlorinated VOC detected in soils was PCE at a concentration of 30 μ g/kg in sample 5367-4 (Ref. 36, pp. 8 – 22). This sample was collected from a depth of 6 to 7 feet below ground surface at the former Compass Plaza Laundromat (Ref. 35, p. 4). No TCE or cis-1,2-DCE were reported in soil sample 5367-4 (Ref. 36 , pp. 8, 9). No other soil sample containe d reportable levels of any chlorinated VOC (Ref. 36, pp. 2, 3, 8 – 23). Although PCE is known to degrad e into TCE in the environment (Ref. 18, p. 8), this area of contaminated soil did not contain any TCE or cis -1,2-DCE (Ref. 36, pp. 3, 8 – 11).

Another potential source investigated is the Positronics Inc. facility, located approximately 0.75 mile east of the Compass Plaza well (Ref. 4, p. 42). The f acility consists of a 0.6 acre main building in the southeast corner of the lot and an out-building located north of the middle of the main building (Ref. 4, p. 10). From 1975 until 1983, the property was owned and operated by Positronics, Inc, a company that manufactured electronic connectors, which involved electroplating (Ref. 4, p. 1387). They also used TCE in their manufacturing process (Ref. 4, p. 1490). Process water from the operation was stored in an on-site lagoon which then discharged to a sinkhole (Ref. 4, pp. 1389, 1390, 1399). In 1981, the facility prepared a plan to cease discharging to the sinkhole, a nd to begin applying the process water directly to the land into an irrigation field on site (Ref. 4, pp. 1390, 1391, 1400). The irrigation system began operating sometime between 1981 and 1987 (Ref. 4, pp. 1387, 1390). Th e facility closed due to a fire in 1983 (Ref. 4, p. 1387). In 1993, the lagoon contents were excavated, dewatered, and disposed of in a landfill. At some point after 1993, the lagoon was filled in with asphalt and concrete debris (Ref. 4, p. 11).

The Positronics facility was discovered and entered into CERCLIS in November 1986 with a CERCLIS Identification number of MOD007447196 (Ref. 7, p. 1). MDNR conducted a Preliminary Assessment (PA) on the property in 1987 and a SI in 1989 (Ref. 4, pp. 1387, 1422). The focus of those investigations was potential contamination from the nickel, copper, and chromium used in the plating process. However, chlorinated solvents were detected in composited shallow soil samples collected in the irrigation field (Ref. 4, pp.1430, 1539; Ref. 6, pp. 13, 18). The SI report recommended a Health Assessment and a dye trace study (Ref. 4, p. 1433). The Positronics site was archived in January 1994 and un-archived in March 2010 (Ref. 7, p. 1)

Three businesses currently operate at the property th at was once Positronics: Greenview Manufacturing, Fairchild Industries, and Ozark Mountain Concepts. None are known to use or have used chlorinated solvents (Ref. 4, p. 11).

Four soil boring locations were sampled on July 27, 2010 as part of the MDNR SI/RSE in the Positronics area (Ref. 4, p. 10, 11, 15). Figure 2 of the SI/RSE report shows the locations of the samples collected (Ref. 4, p. 42). One soil boring location was located at the southern tip of the former lagoon location, northwest of the storage shed along the grass line (Ref . 4, pp. 11, 42, 51). Soil samples were collected from 24.5 feet and from 31 feet. The other three soil boring locations were advanced in the irrigation field area. Soil samples were collected from a 1.5 foot depth at each location (Ref. 4, pp. 11, 42, 52). All

September 2011 17 Source Characterization

### September 2011 18 Source Characterization samples were submitted to the department’s laborato ry for VOC analysis (Ref. 4, pp. 1176-1189). No chlorinated solvents were found in the soil samples submitted for analysis (Ref 4, pp. 15, 16, 42, 1168, 1184, 1226 – 1244).

Due to the unique flow characteris tics of the upper karst aquifer, tracking a ground water plume to a source is difficult. Dye trace studies are proposed fo r the sinkhole at the former Positronics facility to gain a better understanding of the flow characteristics of the aquifer. In addition, soil sampling at the sinkholes is proposed to see if one or more of th ese features may be contributing to the ground water contamination. Speculation exists that unauthorized dumping/burial, or disposal of drummed waste may have occurred in the Rogersville area (Ref .31). This has yet to be confirmed.

### 3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 GENERAL CONSIDERATIONS

Regional Setting

The Compass Plaza Well site lies on the eastern border of the Springfield Plateau of the Ozark Plateau sub-province of the Interior Highlands physiographic pr ovince in Missouri (Ref. 8, p. 1). This area is characterized by rolling upland hills with low relief (Ref 8, p. 1). Surface elevations at the site are about 1,463 feet above mean sea level. Mississippian –age limestone lies beneath the site at a depth of about 30 to 35 feet and includes the Springfield Plateau Aquifer that produces up to 50 gallons per minute and is known to provide water for numerous domestic wells. The Mississipian age rocks of the Springfield Plateau aquifer are 120 to 130 feet thick at the site (Ref. 8, pp. 1, 3, 29). Depth to water is about 100 feet below ground surface (Ref. 8, p. 3). The Springfield Plateau Aquifer is underlain by the Ozark Confining unit which is roughly 30 feet thick regionally (Ref. 8, pp. 1, 3, 29). This confining unit forms a leaky aquitard that separates the Springfield Plateau and underlying Ozark aquifer (Ref. 8, p. 1). The Ozark Aquifer consists of Ordovician- a nd Cambrian-age dolomite and sandst one (Ref. 8, pp. 2, 29. This aquifer is widely used regionally and produces up to 500 gallons per minute (Ref. 8, p. 2). The regional thickness of the aquifer is about 1,600 feet (Ref. 8, pp. 4, 29). The Ozark aquifer is underlain by the St. Francois Confining unit which consis ts of 90 feet of alternating argillaceous (clay) dolomite and shale that are Cambrian aged (Ref. 8, pp. 2, 4, 29).

This area is characterized as karstic terrain. Dissolved limestone bedrock has caused many mapped sinkholes and 14 springs near the site. In addition to th e karstic terrain, the Pearson Fault system aligns with the site and is mapped to within 4 miles of the site to the northwest (see Figure 3 of this documentation record). The fault system has 10 to 20 feet vertical offsets that may lead to interconnectivity of the shallow Springfield Plateau Aquifer a nd the deeper Ozark aquifer (Ref. 8, pp. 3, 5, 8).

Ground Water Migration Pathway Description

Post-Mississippian System

Soils west of Rogersville are of the Wilderness-Vira ton association (Ref 9, p. 5). This association is characterized by deep, moderately well drained, gently sloping soils on uplands and terraces (Ref. 9, p. 5). The predominant soil type in the area is the Needleye silt loam (Ref. 10, p. 3). The Needleye series consist of deep, moderately well dr ained soils on uplands (Ref. 9, p. 4). These soils formed in a thin mantle of loess or other loamy material and clayey residuum weathered from cherty limestone (Ref 9, p. 4). Needleye silt loam is acidic to neutral (pH 3.6 to 7.3) and hydraulic conductivity is roughly 1.4 x 10-3 to 4.2 x 10-5 centimeters per second (cm/sec) (Ref. 4, pp. 18, 19).

The unconsolidated sediments range in thickness from 30 to 35 feet near the site (Ref. 8, p. 2). The regolith, or unconsolidated material above competen t bedrock, is comprised of bedrock residue from chemical weathering and windblown clay. The result is a red, silty clay that contains limestone and chert cobbles at depth (Ref. 8, p. 2). Usable ground water is not known to occur in the overburden.

Stratigraphic unit descriptions are based on logged wells lo cated near the site (Ref. 8, p. 2). The table below lists the geohydrologic properties (thickness, lithology, nature of por osity and permeability, hydraulic conductivity, and hydrologic un it) of the strata beneath the site.

September 2011 19 GW - GeneralAQUIFER, STRATIGRAPHY, AND HYDROLOGY OF THE COMPASS PLAZA WELL TCESystemStratigraphic UnitThickness(feet)LithologyNature of Porosity andPermeabilityHydraulicConductivity(cm/sec)HydrologicUnit

Post MississippianSoil and Regolith30 - 35Cherty, silty clayIntergranular spacethroughout matrix withexception of clay;Moderate permeability1.4x10-3-4.2x10-5 None Springfield Plateau AquiferBurlington-KeokukLimestones, Elsey-ReedsSpring Formation, and PiersonLimestone120 - 130Cherty, coarse-grained,fossiliferouslimestoneLimestone beddingseparations, fractures, anddissolution features;High permeability7.8 x 10-3

MississippianChouteau Group(Northview and ComptonLimestone Formations)27 - 30Argillaceouslimestone and shaleBedding separations,fractures, and possibledissolution features;Moderately lowpermeability1x10-5-5x10-6 Ozark Confining Unit

OrdovicianCotter and Jefferson CityDolomites, RoubidouxFormation, and GasconadeDolomiteapprox.1,600Dolomite, chertydolomite,sandstone,dolomiticsandstone,argillaceousdolomite, and minorshalesBedding separations andfractures;Moderate permeability1 x 10-4-1 x 10-5 Ozark AquiferEminence and PotosiDolomites

CambrianDerby-Doe Run Dolomites90Medium-crystallinedolomite with bedsof silt, shale, andsandBedding separations andfractures;Low permeability1x10-8 St. Francois Confining UnitSource: Ref. 8, p. 29September 2011GW - General20

### Mississippian System

The uppermost bedrock units are of Osagean Series of the Mississippian System (Refs. 11, pp. 5, 16, 18; 12). The Mississippian-age rocks beneath the site are divided (from youngest to oldest) into the Burlington Limestone and Reeds Spring-Elsey, and Piers on Formations (Refs. 8, p. 3; 11, p. 5; 12).

These formations consist of fossilif erous limestone and chert (Ref. 8, p. 3). The Mississippian-age rocks in the Springfield Plateau aquifer beneath the site ra nge from approximately 120 to 130 feet thick (Ref. 8, p. 3). Due to the acid solubility of limestone, the sh allow bedrock is deeply dissolved (karst). The

dissolution leads to an uneven bedrock surface with cutters and pinnacles along with cave and sinkhole formation (Ref. 8, p. 3). Based upon topographic maps, there are many sinkholes lie near the site (Ref. 8, p. 5). There are also 14 springs near the site (Ref. 8, p. 5). Based upon this information and the limestone bedrock, the site lies within a karst area (Ref. 8, p. 5).

The Ozark confining unit makes up the deepest and oldest Mississippian-age rocks beneath the site consisting of the Northview and Compton Limestone Formations (Ref. 8, p. 3). These formations are both in the Chouteau Group (Ref. 8, p. 29). These formations are composed of argillaceous (silty) limestone (Ref. 8, p. 3). The Compton Limestone and Northview Formation are roughly 30 feet thick

beneath the site and form an effective barrier to the underlying Ozark Aquifer where they are not compromised by faults or open boreholes (Ref. 8, p. 3).

Ordovician and Cambrian Systems

Underlying the Mississippian age formations are prim arily dolomites of Ordovician and late Cambrian age (Ref. 8, p. 29). These formations described below make up the Ozark Aquifer. The Ozark aquifer consists of the Ordovician- and Cambrian-age rocks ben eath the site divided into the Jefferson City/Cotter Dolomite, Roubidoux Formation, and Gasconade Dolomite formations (Ref. 8, p. 4). These formations consist dominantly of dolomite and ch erty dolomite with occasional sands tone and cherty sandstone beds (Ref. 8, p. 4). The Ordovician-age rocks beneath the site are roughly 1,000 feet thick. The Cambrian-age

Eminence and Potosi Dolomites consist of medium- to coarsely crystalline dolomite with nodular chert (Ref. 8, p. 4). The Cambrian-age rocks beneath the site are 550 feet thick (Ref. 8, p. 4).

Below the formations encompassing the Ozark aqui fer are the Davis Formation (known as the St. Francois Confining Unit) and the Bonneterre Dolomite and Lamotte-Regan Sandstone formations (Refs. 8, pp 4, 29; 11, p. 5). The latter two formations encompass the St. Francois aquifer (Ref. 11, p. 5). The St. Francois aquifer is not known to be used near the site (Ref. 8, pp 4, 29).

Regional Aquifers

The site is located in the Springfield Plateau ground water province in Missouri which covers all or parts of 27 counties in southwestern and west-central part of the state (Ref. 11, pp. 4, 6). Thick dolomites and sandstones comprising the St. Francois, Ozark, and Springfield Plateau aquifers underlie the region (Ref. 11, p. 4, 6). The state has identified 573 register ed wells near the site (Ref. 8, pp 1, 9 - 28). These wells are shown on Figure 1 of reference 8 (Ref. 8, p. 7) and reported constructi on details are presented in Table 1 of reference 8 (Ref. 8, pp. 9 – 28). Table 1 shows the database where the well registration is kept, the well identification number, the total depth of the we ll, the footage of casing, the elevation of the well, the reported static water level at the well, date insta lled, use, owner of the well at the time of registration and the aquifer, or aquifers it draws from (Ref. 8, pp. 9 – 28). Prior to 1987, registry of private wells was not required, so some existing older wells may not be included and the number of private wells may be greater than the 573 reported (Ref. 8, p. 2).

September 2011 GW - General 21

### Springfield Plateau Aquifer : 

### The first aquifer encountered beneath the site is the Springfield Plateau Aquifer which is reported at a depth of 100 feet bgs (Ref . 8, p. 3). The aquifer consists of a sequence of cherty limestones of Mississippian age (Ref. 8, p. 3). The lowest formation in the aquifer is the Pierson Limestone, which is considered by some to belong to the Ozark confining unit (Ref. 11, pp. 5, 7). This aquifer produces up to 50 gallons per minute (Ref. 8, p 1). The Springfield Plateau is an unconfined karstic aquifer (Ref. 8, p. 3; 11, p 18). The Springf ield Plateau Aquifer is known to provide water for 259 of the 573 wells near the site (Ref 8, p. 1). Based on the reported depth to grou nd water of 100 feet below ground surface and the reported depth to the bottom of the aquifer of between 150 and 165 feet below ground surface, this aquifer ranges from roughly 50 to 65 feet thick beneath the site (Ref 8, pp. 3, 29). Water reportedly moves westward through the Springfiel d Plateau Aquifer (Refs. 8, p. 3; 11, p. 18). A dye trace study by the state showed movement to the s outh southeast (Ref 4, pp. 32, 46). The hydraulic conductivity of the Springfield Plateau Aquifer is roughly 7.8 x 10 -3 

### centimeters per second (cm/sec) (Ref. 8. p. 3). Due to the karst nature, permeability and flow gradient characteristics may vary over short distances (Ref. 8, p. 3).

The Ozark Confining Unit is roughly 30 feet thick at Rogersville (Ref. 12, p. 1). This confining unit forms a leaky aquitard that separates the Springfield Plateau and Ozark aquifers (Ref. 8, pp. 1, 3, 5). This confining unit consists of Mississippian-age lim estone and shale referred to as the Northview and Compton Limestone Formations and h as a hydraulic conductivity of 1.0 x 10 -5 

### to 5.0 x 10 -6 

### cm/sec. (Ref. 8, pp. 3-4, 29).

Approximately 45% of the recorded wells near the site have open boreholes connecting the Springfield Plateau Aquifer with the underlying Ozark Aquifer (Ref. 8, pp. 1, 2). Also, the Pearson Fault System is mapped to within four miles of the site (Ref. 8, pp. 2, 8; also see Figure 3 of this documentation record). This fault system is comprised of several en-echelon fau lts with individual offsets of 10 to 20 feet (Ref. 8, p. 2). Within the fault zone, there is sufficient off set to allow interconnection between aquifers. Near the site, 568 wells penetrated the Ozark Confining unit. Of these wells, 314 are cased through the confining unit (Ref. 8, p. 2).

Ozark Aquifer: Water infiltration from the Springfield Plateau aquifer through the Ozark confining unit is one way the Ozark aquifer is recharged (Ref. 11, pp. 14, 15). The Ozark aquifer consists of the Ordovician- and Cambrian-age rocks beneath the site divided into the Jefferson City/Cotter Dolomite, Roubidoux Formation, and Gasconade Dolomite form ations. These formations consist dominantly of dolomite and cherty dolomite with occasional sandstone and cherty sandstone beds (Ref. 8, p. 4). The Ordovician-age rocks beneath the site are roughly 1, 000 feet thick. The Cambrian-age Eminence and Potosi Dolomites consist of medium- to coarsely crys talline dolomite with nodular chert (Ref. 8, p. 4). The Cambrian-age rocks beneath the site are 550 feet thick (Ref. 8, p. 4). The Ozark Aquifer has a hydraulic conductivity that ranges from 1.0 x 10 -4 

### to 1.0 x 10 -5 

### cm/sec. (Ref. 8, p. 4).

Aquifer Interconnections

Information about the geology suggests the Spri ngfield Plateau Aquifer and Ozark Aquifer are

interconnected. This interconnection is based on the following information:

• As documented in Section 3.1.1 of this document ation record, TCE was initially detected in three wells referred to as the Compass Plaza well, C itizen’s Bank of Rogersville well, and the Jamestown Irrigation well (Ref. 4, pp. 5, 41). The Compass Plaza well has steel casing that is 263 feet long, a total depth of 750 feet and a pump which is set at 465 feet (Ref. 23). The Citizen’s Bank of Rogersville well has steel casing th at is 260 feet long, a total depth of 545 feet and a pump which is set at 360 feet (Ref. 24). The Jamestown Irrigation well has steel casing that is 210 feet long, a total depth of 600 feet and a pump which is set at 460 feet (Ref. 25). All three

September 2011 GW - General 22

### September 2011 GW - General 23 

### wells are cased through the Ozark confining unit and draw from the Ozark aquifer (Ref. 8, p. 29). These wells provide evidence that TCE has migrated to the Ozark aquifer.

• Two of the domestic wells samples by MDNR and EPA are completed and draw exclusively from the lower Ozark aquifer and have been shown through analytical evidence to contain TCE indication contamination has migrated across the confining unit. The domestic wells with state

well identification numbers of 0273248A and 00902 75A reportedly draw from the Ozark aquifer exclusively (Ref. 8, pp. 9, 10). As documented in Section 3.1.1 these wells with MDNR designations of 102 and 121 contain TCE indicating contamination has migrated through the Ozark confining unit (Ref. 4, p. 57).

• Approximately 254 of the 573 recorded and regi stered wells near the site have open (uncased) boreholes connecting the Springfield Plateau Aqui fer with the underlying Ozark Aquifer (Ref. 8, pp. 1, 2). Of these, 71 are reported to be open hole completions drawing from both the Springfield Plateau and Ozark aquifers within approximately 2-miles of the site (Ref. 8, pp. 9 – 14). In these wells that are registered with the state, casing lengths range from five feet long (Ref. 8, p. 10) to 130 feet long (Ref. 8, p. 12). Prior to 1987, registry of private wells was not required (Ref. 8, p. 2). Registered domestic we lls installed before 197 0, typically have casing lengths of less than 50 feet and draw from both aqui fers (Ref. 8, pp. 9, 10, 15, 21). Therefore, older domestic unregistered wells within two mil es are likely of open hole construction and draw from both aquifers.

• The 30 foot thick Ozark Confining unit is descr ibed by the Missouri Geological Survey Program, Division of Geology and Land Survey as being a leaky aquitard (Ref. 8, p. 1), and that the Ozark aquifer is recharged to a large extent from the Springfield Plateau aquifer (Ref. 11, pp. 14, 15).

SUMMARY OF AQUIFER(S) BEING EVALUATED

Aquifer

No. Aquifer Name Is Aquifer

Interconnected with Surficial Aquifer within 2 miles? (Y/N/NA) Is Aquifer

Continuous Within 4-mileTDL? (Y/N) Is Aquifer Karst? (Y/N)

1 Springfield Plateau Aquifer NA Yes Yes

2 Ozark Aquifer Yes Yes No

### 3.1 LIKELIHOOD OF RELEASE

3.1.1 OBSERVED RELEASE

Direct Observation:

An observed release by direct observation is not scored.

Chemical Analysis:

As documented below, an observed release to the ground water migration pathway in the combined Springfield Plateau and Ozark aquifer has been establi shed. This is based on analysis of ground water collected from private, irrigation and community dr inking water wells with open hole construction across both aquifers.

The well that serves the Compass Plaza is located be hind the buildings in Compass Plaza and is located most closely to the former Compass Cleaners & Laun dromat (Ref. 4, pp. 5, 41, 44, 48). The well, constructed in 2004, has a total depth of 750 feet and draws water from the Ozark Aquifer (Refs. 4, p. 7; 23). Prior to the summer of 2009, the Compass Plaza well was considered a non-community transient water supply (Ref. 4, p. 7). A non-comm unity transient water supply is defined as serving an average of at least 25 individuals daily at least 60 da ys out of the year, and is not required under Missouri regulations to conduct extensive chemical testing (R ef. 4, p. 7). In the spring of 2009, the Graceland Daycare connected to the Compass Plaza well which changed the status of the well from a transient to a non-transient water supply (Ref. 4, p. 7). A non-transient non-community well is defined as a public water system that is not a community water system th at regularly serves at least 25 of the same persons over 6 months per year (Ref. 4, p. 7). Non-transient non-community wells are required to conduct periodic chemical testing. The first such testing w as conducted on June 18, 2009 (Ref. 4, p. 7). TCE was

detected at 3.73 μ g/L (Ref. 4, pp. 7, 62, 63). The Compass Plaza well was disconnected on September 29, 2010 (Ref. 4, pp. 7, 1555). The Compass Plaza development is now served by water supplied by the City of Rogersville Public Water System (Ref. 4, p. 7).

Following the initial detection of TCE in the Comp ass Plaza public well in June 2009, successive rounds of sampling were conducted by MDNR beginning with wells nearest Compass Plaza and extending outward (Ref. 4, p. 25). Sampling plans prepared for the domestic well sampling events are provided in the appendix of the SI/RSE report (Ref. 4, pp . 1499-1505, 1514-1524, 1538-1543). Ground water samples collected by MDNR were analyzed by th e state’s environmental laboratory within the Environmental Services Program by EPA safe drinking water act method 524.2 for volatile organic compounds. (Ref. 4, pp. 26, 1503). Seven public dr inking water wells located nearest the site were sampled on a number of occasions between March and Ju ly 2010 (Ref. 4, p. 25). These wells are shown in Figure 5 of the SI/RSE report (Ref. 4, p. 45). Th ese wells are also provided on Figures 2 and 3 of this

documentation record.

Private wells located near the site were identifie d using well records from MDNR Division of Geology and Land Survey (DGLS) databases. Additional we lls were added to the sampling program based on requests by private residents following a public meeti ng held in Rogersville on May 25, 2010. In all, access was gained to 121 private drinking water we lls, and these were sampled over the period between March, April and September of 2010 (Ref. 4, p. 26). The list of sampled private wells is included in Table C1 of the SI/RSE report (Ref 4, pp. 57 -59). Figure 5 of the SI/RSE report shows all public and private well sampling locations (Ref. 4, p. 45).

September 2011 GW – Likelihood of Release 24

### September 2011 GW – Likelihood of Release 25 

### During initial rounds of sampling, samples were colle cted only from outside taps nearest the wellhead. Subsequent rounds of sampling also included sample coll ection at an inside tap (typically the kitchen). Duplicate samples were collected, and trip blanks pr ocessed as specified in the Quality Assurance Project Plan (QAPP) (Ref. 4, p. 26). All samples were submitted to the department’s Environmental Services Program (ESP) laboratory for analysis of VOCs by EPA drinking water method 524.2 (Ref. 4, p. 26). The analytical data were validated by Tetra Tech (Ref. 17). The reporting limits presented in the data packages are equivalent to sample quantitation limits (SQLs) (Ref. 17, p. 1).

In the summer of 2010, MDNR requested that EPA Region 7 to provide alternative water supply to households drinking contaminated ground water (R ef. 4, p. 1557-1558). EPA Region 7 tasked the START contractor to provide removal assessment s upport by resampling State identified contaminated wells and also perform post filtration sampling at we lls where wholehouse filtration systems were to be installed (Ref. 13, pp. 5, 11, 13). Samples were collected August 16 and 17, 2010 and post filtration samples were collected August 25, 2010 (Ref.14).

Chlorinated solvents reported by both EPA and MDNR in private wells include TCE, 1,1,2-trichloroethane (TCA), and cis- 1,2-dichloroethene (DCE) (Refs.4, pp. 28, 29, 30; 15, pp. 3, 10, 11). The locations of the wells sampled are shown on Fi gure 5 of the SI/RSE report (Ref. 4, p 45). The following pages further discuss background concentra tion and release samples used in establishing an observed release by chemical analysis.

### Background Concentrations:

The MDNR performed multiple rounds of public an d private water well samples. Initial sampling was conducted by the MDNR’s PDWB and focused on public wells (Ref. 4, pp. 4, 7). After several rounds of sampling public wells, the site was referred to the MDNR HWP in March 2010 for further assessment under CERCLA (Ref. 4, pp. 4, 7). Ground water sampling by the HWP included public and private drinking water wells (Ref. 4, pp. 25, 26). Access was gained by th e HWP to 121 private drinking water wells which were sampled between Ma rch and September of 2010 (Ref. 4, p. 26). Chlorinated solvents were reported by the State in 12 of the 121 wells sampled (Ref. 4, pp. 28 – 30).

Initial sampling by the PDWB in June, July and September of 2009 did not include background well sampling (Ref. 4, pp. 62 – 67). Only the well asso ciated with Compass Plaza is known to have been sampled in 2009. On March 8, and 16, 2010 additiona l public water supply wells were sampled including the Compass Plaza well (Ref. 4, pp. 68, 92), City of Rogersville well 4 (Ref. 4, p. 70), City of Rogersville well 1 (Ref. 4, p. 72), Citizens Bank of Rogersville well (Ref. 4, pp. 74, 90), Bills Quick Mart well (Ref. 4, p. 76), Logan Rogersville Middle School we ll (Ref. 4, p. 80), Logan Rogersville High School well (Ref. 4, p. 82), Logan Rogersville Primary Scho ol well (Ref. 4, p. 84), Willow Green Gardens Tree Farm well (Ref. 4, p. 86), and the Jamestown Irrigation we ll (Ref. 4, p. 94). Samples were analyzed for VOCs using EPA method 524.2 (Ref. 4, pp. 70-87).

Later sampling by the state HWP did consider background sampling. The HWP designated three wells as background as part of their investigation (Ref. 4, pp. 30, 57, 58). These wells were designated as well 162, 163 and 179 (Ref 4, pp. 30, 57, 58). The inset of Figure 5 of the SI/RSE report shows two of the wells to be west of Rogersville and the third to be east of Rogersville (Ref. 4, p. 45). It appears these wells were sampled one time in April of 2010 (Ref. 4, p. 30). Samples were analyzed for VOCs using EPA method 524.2 (Ref. 4, p. 197). No informa tion was provided on well depths for any of the background wells sampled by the HWP. Although these three wells were designated as background, there are many other wells that were sampled duri ng the SI/RSE evaluation that did not contain TCE, cis

1,2-DCE or 1,1,2-TCA. Figure 5 of the SI/RSE report (Ref. 4, p. 45) shows most of the private wells sampled. On that map only the wells shaded red or or ange contained measurable levels of TCE, all others shown did not contain TCE (Ref. 4, pp. 26 – 30, 45).

Initial sampling by EPA occurred in August 2010 in accordance with the QAPP dated August 13, 2010 (Refs. 13, 14). Initial sampling by EPA was at priv ate wells where contamination was found previously by MDNR as well as several other private wells locat ed near the area of known contamination (Ref. 13,pp. 5, 13). In addition, post filtration samples were collected from homes with newly installed wholehouse filtration systems (Refs. 13, pp. 5, 13; 14, pp. 12 , 14, 16, 18, 19, 21). Th ese samples were analyzed for VOCs under the EPA contract lab program (CLP) using EPA Region 7 Method 3230.09, which meets the requirements of EPA Method 524.2 (Refs. 13, p. 8; 14, pp. 3-24; 15, p. 4; 16; 39, p. 1). Of the wells sampled, one well at 10118 East Farm Road 186, w as shown to be free of TCE contamination and is selected as background. This well was also sampled by the state of Missouri and is listed as MDNR location ID 177 (Refs. 4, pp. 45, 57; 14, p. 22; 15, p. 3, 15). No information was available pertaining to the depth of the well.

The locations of all background wells in relation to the ground water plume are shown on Figure 3 of this documentation record. Known information about the dept hs of the wells is presented in the table on the following page.

September 2011 GW – Likelihood of Release 26

### September 2011 GW – Likelihood of Release 27 

### BACKGROUND WELL INFORMATION

Well Code a Screened

Interval*

(ft bgs) Well Depth (ft bgs) Well Depth (ft amsl) Year

Drilled References

162 Not Reported Not Reported Unknown Not Reported 4, pp. 196 – 200, 214,

483 - 486

163 Not Reported Not Reported Unknown Not Reported 4, pp. 196 – 200, 214,

487 - 490

179 Not Reported Not Reported Unknown Not Reported 4, pp. 196 – 200, 216,

560 - 563

Rogersville W1 175 – 1,260 1,260 221 1954 20, p. 2; 37, p. 1; 38, pp. 1, 3 Rogersville W4 450 – 1,150 1,150 unknown 1996 20, p. 2; Bills Quick Mart well 200 - 600 600 unknown 1984 26, p. 3 Logan Rogersville Middle

School well 350 – 685 685 738 1967 27

Logan Rogersville High

School well 358 – 1,005 1,005 415 2004 28

Logan Rogersville Primary School well 257 - 758 758 668 1956 29

Willow Green Gardens

Tree Farm well 197 - 810 810 unknown 2000 30

177 (EPA sample 5049-20) Not Reported Not Reported Unknown Not Reported 4, pp. 45, 57; 14, p. 22

Notes:

a Well codes for private wells sampled by MDNR HWP are explained in reference 4, pp. 57, 58, 59. * Wells in the Springfield plateau typically consist of an unlined, open borehole below the casing (Ref. 11, pp. 21 - 24). ft bgs Feet below ground surface

ft amsl Feet above mean sea level

NA Not availableBACKGROUND CONCENTRATIONSWellCodeaLaboratoryNumberSampleDateContaminantContaminantConcentration (μg/L)Reporting Limit(μg/L)References162100074004/14/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 196 – 200, 214,483 – 486; 17, p. 1163100074104/14/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 196 – 200, 214,487 – 490; 17, p. 1179100044104/15/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 196 – 200, 216,560 – 563; 17, p. 14, pp. 72, 73, 163Rogersville WL1AB1591403/08/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.5Rogersville WL4AB1591303/08/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 70, 71, 163Bills Quick MartAB1616203/16/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 76, 77Logan Rogersville MiddleSchoolAB1616403/16/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 80, 81Logan Rogersville HighSchoolAB1616503/16/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 82, 83, 166Logan Rogersville PrimarySchoolAB1616603/16/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 84, 85, 167Willow Green Gardens TreeFarmAB1616703/16/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, pp. 86, 87, 1681775049-2008/25/2010TCEcis-1,2-DCE1,1,2-TCANDNDND0.50.50.54, p. 57; 14, pp. 2, 22; 15,pp. 2, 3, 14, 15; 16,pp. 30 - 32Notes:aWell codes are explained in reference 4, pp. 57, 58, 59.September 2011GW – Likelihood of Release28September 2011GW – Likelihood of Release29μg/L Micrograms per literDCE DichloroetheneND Not detectedTCA TrichloroethaneTCE Trichloroethene

### Contaminant Concentrations:

Contaminated samples documenting the observed release were collected from private and public drinking water wells. Well information such as screening interval, well depth, and year drilled was not available for most of the private wells because they were not re gistered with the State of Missouri, current owners did not know the depths of wells, or investig ators failed to collect the information.

CONTAMINATED WELL INFORMATION

Well Code a Screened
Interval *

(ft bgs) Depth (ft bgs) Depth (ft amsl) Year

Drilled References

Compass Plaza Well 263 - 750 750 unknown 2004 23

Citizen’s Bank of Rogersville 260 - 545 545 935 2001 24

Jamestown Irrigation well 210 - 600 600 unknown 2008 25

MDNR 176 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 198, 199

MDNR 168 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 198, 199

MDNR 170 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 199

MDNR 102 168 - 522 522 908 2001 4, pp. 28, 57, 198; 8, p. 9

MDNR 104 Not Reported Not Reported unknown unknown 4, pp. 28, 57, 198, 199

MDNR 118 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 198, 199

MDNR 121 147 - 405 405 1045 1993 4, pp. 29, 57, 198, 199; 8, p. 10

MDNR 117 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 198, 199

MDNR 114 Not Reported Not Reported unknown unknown 4, pp. 28, 57, 198, 199

MDNR 124 Not Reported Not Reported unknown unknown 4, pp. 29, 57, 198, 199

MDNR 181 Not Reported Not Reported unknown unknown 4, pp. 30, 58,198, 199

MDNR 251 Not Reported Not Reported unknown unknown 4, pp. 30, 58, 198, 199

No code EPA sample 5049-15 Not Reported ~400 unknown 1976 14, p. 17; 19, p. 10

Notes:

* Wells in the Springfield plateau typically consist of an unlined, open borehole below the casing (Ref. 11, pp. 21 - 24).

a Well codes are explained in reference 4, pp. 57, 58, 59. ft bgs Feet below ground surface

ft amsl Feet above mean sea level



### September 2011 GW – Likelihood of Release 30CONTAMINATED WELL SAMPLE CONCENTRATIONSWell CodeaLaboratoryNumberSampleDateContaminantContaminantConcentration(μg/L)MethodReporting Limit(μg/L)ReferencesAB1589203/08/2010TCEcis-1,2-DCE3.071.070.50.54, pp. 28, 68, 69, 165; 17, p. 1Compass PlazaWellAB1617003/16/2010TCEcis-1,2-DCE3.841.210.50.54, pp. 28, 92, 93, 170; 17, p. 1AB1591503/08/2010TCEcis-1,2-DCE2.250.660.50.54, pp. 74, 75, 163; 17, p. 1Citizen’s Bankof RogersvilleAB1616903/16/2010TCEcis-1,2-DCE2.110.690.50.54, pp. 90, 91; 17, p. 1JamestownIrrigation wellAB1617103/16/2010TCEcis-1,2-DCE4.961.840.50.54, pp.28, 94, 95, 169; 17, p. 1100043804/15/2010TCE1,1,2-TCA3130.840.50.5100370104/22/2010TCE1,1,2-TCA3230.830.54, pp. 29, 57, 198, 199, 550, 551, 604, 605,618, 619; Ref. 17, p. 1.0.51765049-1108/17/2010TCE1806.314, p.13; 15, pp. 10, 11; 16, p. 18100074704/15/2010TCE1.100.5100369204/21/2010TCE1.330.54, pp. 29, 57, 198, 199, 512, 572, 1327, 1377,1378; Ref. 17, p. 1.100371509/13/2010TCEcis-1,2-DCE1.410.50.50.51685049-308/16/2010TCE1.10.54, p. 57; 14, p.5; 15, pp. 6, 7; 16, p. 5100075004/15/2010TCEcis-1,2-DCE2.270.830.50.5100369704/21/2010TCEcis-1,2-DCE2.320.920.54, pp. 29, 57,198, 199, 524, 581, 582; Ref. 17,p. 1.0.51705049-508/16/2010TCEcis-1,2-DCE1.20.580.50.514, p.7; 15, pp. 8, 9; 16, pp. 7, 8100068903/30/2010TCEcis-1,2-DCE5.411.910.50.5100072004/14/2010TCEcis-1,2-DCE5.442.030.54, pp. 28, 57, 198, 199, 234, 235, 378, 404;Ref. 17, p. 10.51025049-1808/17/2010TCEcis-1,2-DCE5.41.80.50.514, p.20; 15, pp. 14, 15; 16, pp. 27 - 29100072404/14/2010TCE0.890.5100372509/15/2010TCEcis-1,2-DCE1.260.650.54, pp. 28, 57, 198, 199, 420, 1366, 1381, 1382;Ref. 17, p. 10.51045049-708/16/2010TCE1.1 J*0.514, p. 9; 15, pp. 5, 8, 9; 16, pp. 10, 11September 201131GW – Likelihood of ReleaseCONTAMINATED WELL SAMPLE CONCENTRATIONS (Continued)September 2011GW – Likelihood of Release32Well CodeaLaboratoryNumberSampleDateContaminantContaminantConcentration(μg/L)MethodReporting Limit(μg/L)References100378503/31/2010TCEcis-1,2-DCE4.791.610.50.5100072504/14/2010TCEcis-1,2-DCE5.191.80.50.54, pp. 29, 57, 198, 199, 238, 239, 390, 424;Ref. 17, p. 11185049-1308/17/2010TCE1.30.514, p.15; 15, pp. 12, 13; 16, pp. 19 - 21100379003/31/2010TCE0.650.5100073004/14/2010TCE0.970.54, pp. 29, 57, 198, 199, 236, 237, 342, 444;Ref. 17, p. 11215049-608/16/2010TCE0.660.514, p.8; 15, pp. 8, 9; 16, pp. 8 - 10100378403/30/2010TCEcis-1,2-DCE3.571.280.50.5117100073304/14/2010TCEcis-1,2-DCE2.91.360.50.54, pp. 28, 57, 198, 199, 238, 239, 386, 456;Ref. 17, p. 1100378103/30/2010TCEcis-1,2-DCE6.362.70.50.5100073404/14/2010TCEcis-1,2-DCE6.742.470.50.54, pp. 28, 57, 198, 199, 228, 229, 320, 460;Ref. 17, p. 11145049-908/17/2010TCEcis-1,2-DCE6.22.20.500.5014, p. 11; 15, pp. 10, 11; 16, pp. 13, 14100073604/14/2010TCE0.850.5100372009/15/2010TCE0.660.54, pp. 29, 57, 198, 199, 468, 1347, 1379, 1380;Ref. 17, p. 11245049-808/17/2010TCE0.740.514, p. 10; 15, pp. 8, 9; 16, pp. 11 - 13100370604/22/2010TCEcis-1,2-DCE4.141.290.50.54, pp. 30, 58, 612, 613, 620, 621; Ref. 17, p. 11815049-408/16/2010TCEcis-1,2-DCE4.51.40.50.514, p. 6; 15, pp. 6, 7; 16, pp. 5, 6100057106/15/2010TCEcis-1,2-DCE5.413.130.50.54, pp. 30, 58, 641, 687, 688, 783; Ref. 17, p. 12515049-108/16/2010TCEcis-1,2-DCE5.82.60.50.514, p. 3; 15, pp. 6, 7; 16, pp. 1, 2No code, EPAsample 5049-155049-1508/17/2010TCEcis-1,2-DCE4.41.60.50.514, p. 17; 15, pp. 12, 13; 16, pp. 22 – 24Notes:aWell codes are those used by MDNR*TCE in this sampled is estimated and theresult is biased low due to low recoveriesof surrogate analytes (Ref. 15, p. 5)J The identification of the analyte is acceptable; the reported value is an estimate (Ref. 15, p. 2)DCE Dichloroetheneμg/L Micrograms per literTCA TrichloroethaneTCE Trichloroethene

### Level I Samples

A Level I drinking water sample is defined as a drin king water sample with concentration of a hazardous

substance such as TCE that meets the criterion of an observed release at or above the hazardous substance’s drinking water benchmark (Ref. 1, Sec tion 2.5.2). Health-based benchmarks for the ground water migration pathway include the maximum cont aminant level (MCL), the cancer risk screening concentration (CRSC), and the Non Cancer Risk scree ning concentration (NCRSC) (Ref. 1, Table 3-10). The EPA has set the following hea lth-based benchmarks for TCE, cis -1,2-DCE, and 1,1,2-TCA:

• For TCE, MCL is 0.005 mg/L (5 μg/L), CRSC is 0.00021 mg/L (0.21 μg/L), and NCRSC is 0.011 mg/L (11 μg/L) (Ref. 2, p. 6).

• For cis -1,2-DCE, MCL is 0.070 mg/L (70 μg/L) and NCRSC is 0.36 mg/L (360 μg/L) (Ref. 2, p, 13).

• For 1,1,2-TCA, MCL is 0.003 mg/L (3 μg/L), CRSC is 0.0015 mg/L (1.5 μg/L), and NCRSC is 0.15 mg/L (150 μg/L) (Ref. 2, p, 14).

The lowest benchmark for TCE is the CRSC which is 0.21 μg/L. As shown in the contaminated well sample concentrations table a bove, none of the wells contained cis -1,2-DCE or 1,1,2-TCA at concentrations that exceed any benchmarks. Th e following table shows the drinking water samples collected at Compass Plaza Well TCE that exceeded the CRSC for TCE.

Well Code a Sample Date TCE

Concentration ( μ g/L) Reference

03/08/2010 3.07 Compass Plaza Well 03/16/2010 3.84 2, p. 6; 4, pp. 28, 68, 69, 92, 93, 165, 170

03/08/2010 2.25 Citizens Bank of Rogersville 03/16/2010 2.11 2, p. 6; 4, pp.74, 75, 90, 91, 163

04/15/2010 313

04/22/2010 323 MDNR 176

08/17/2010 180 2, p. 6; 4, pp. 29, 57, 198, 199, 550, 551, 604, 605, 618, 619; 14, p.13; 15, pp. 10, 11; 16, p. 18

04/15/2010 1.10

04/21/2010 1.33

09/13/2010 1.41 2, p. 6; 4, pp. 29, 57, 198, 199, 512, 572, 1327, 1377, 1378; 14, p.5; 15, pp. 6, 7 MDNR 168

08/16/2010 1.1

04/15/2010 2.27

04/21/2010 2.32 MDNR 170

08/16/2010 1.2 2, p. 6; 4, pp. 29, 57, 198, 199, 524, 581, 582; 14, p.7; 15, pp. 8, 9

03/30/2010 5.41

04/14/2010 5.44 MDNR 102

08/17/2010 5.4 2, p. 6; 4, pp. 28, 57, 198, 199, 234, 235, 378, 404; 14, p.20; 15, pp. 14,

15

04/14/2010 0.89

09/15/2010 1.26 MDNR 104

08/16/2010 1.1 2, p. 6; 4, pp. 28, 57, 198, 199, 420, 1366, 1381, 1382; 14, p. 9; 15, pp. 5, 8, 9

03/31/2010 4.79

04/14/2010 5.19 MDNR 118

08/17/2010 1.3 2, p. 6; 4, pp. 29, 57, 198, 199, 238, 239, 390, 424; 14, p.15; 15, pp. 12,

13



### September 2011 GW – Likelihood of Release 33

### September 2011 GW – Likelihood of Release 34 Well Code a Sample Date TCE

Concentration ( μ g/L) Reference

03/31/2010 0.65

04/14/2010 0.97 MDNR 121

08/16/2010 0.66 2, p. 6; 4, pp. 29, 57, 198, 199, 236, 237, 342, 444; 14, p.8; 15, pp. 8, 9

03/30/2010 3.57 MDNR 117

04/14/2010 2.9 2, p. 6; 4, pp. 28, 57, 198, 199, 238, 239, 386, 456

03/30/2010 6.36

04/14/2010 6.74 MDNR 114

08/17/2010 6.2 2, p. 6; 4, pp. 28, 57, 198, 199, 228, 229, 320, 460; 14, p. 11; 15, pp. 10, 11

04/14/2010 0.85

09/15/2010 0.66 MDNR 124

08/17/2010 0.74 2, p. 6; 4, pp. 29, 57, 198, 199, 468, 1347, 1379, 1380; 14, p. 10; 15, pp. 8, 9

04/22/2010 4.14 MDNR 181

08/16/2010 4.5 2, p. 6; 4, pp. 30, 58, 612, 613, 620, 621; 14, p. 6; 15, pp. 6, 7

06/15/2010 5.41 MDNR 251

08/16/2010 5.8 2, p. 6; 4, pp. 30, 58, 641, 687, 688, 783; 14, p. 3; 15, pp. 6, 7

No code (EPA sample 5049-015) 08/17/2010 4.4 2, p. 6; 14, p. 17; 15, pp. 12, 13

Notes:

a Well code is designated by the MDNR (Ref. 4, pp. 57 – 59).

μ g/L Micrograms per liter



### As documented above and shown in Figure 2, chlorinated solvents including TCE, 1,1,2-TCA and cis

1,2-DCE were reported in public and pr ivate wells located to the south and west of Rogersville, Missouri. By mid June 2010, the MDNR HWP had sampled 121 we lls and 13 contained TCE; six of these wells had TCE at concentrations exceeding the EPA MCL (Ref. 4, pp 1538, 1539). Numerous private wells around the plume have been sampled and shown not to contain the chlorinated solvents (Ref. 4, pp. 25, 26, 45). Also as part of the SI, the state conducted a search for possible sources of the ground water contamination and collected soil samples from suspect areas (Ref. 4, pp. 9 – 17). No source of the TCE in ground water was identified (Ref. 4, p. 17). As documented in Section 2.2, investigations conducted to date in and around Rogersville have not identifie d a definite source for the chlo rinated solvents found in ground

water.

Hazardous Substance Released

Significantly elevated concentrations of VOCs including TCE, cis-1,2-DCE and 1,1,2-TCA have been observed in ground water sampled from public and priv ate drinking water wells south and west of Rogersville Missouri. Sampling activ ities conducted to date have not id entified the source of chlorinated solvents found in ground wa ter wells. Because the area is karst, a nd ground water flow is unpredictable, tracking this contamination back to a source cont aining TCE, 1,2-DCE, and/or 1,1,2-TCA has been

unsuccessful. In accordance with Section 3.1.1 of refe rence 1, an observed release by chemical analysis has been established and a value of 550 is assigne d below and entered on line 1 of HRS Table 3-1.

Because an observed release has been establis hed, potential to release is not evaluated.

Ground Water Observed Release Factor Value: 550

### 3.2 WASTE CHARACTERISTICS

3.2.1 TOXICITY/MOBILITY

The hazardous substances listed in the table below have been documented in and associated with the ground water plume (Source 1). As documented in section 3.1.1 above, these hazardous substances were detected in release samples at concentrations significantly exceeding background levels.

Hazardous

Substance Source

No. Toxicity

Factor

Value Mobility

Factor

Value Does Hazardous

Substance Meet

Observed Release? (Y/N) Toxicity/ Mobility (Table 3-9) References
1,1,2-

Trichloroethane 1 1,000 1 Yes 1,000 1, Sections 3.2.1, 3.2.1.2; 2, p. 12

Trichloroethene 1 10,000 1 Yes 10,000 1, Sections 3.2.1, 3.2.1.2; 2, p. 6

cis -1, 2-

Dichloroethene 1 100 1 Yes 100 1, Sections 3.2.1, 3.2.1.2; 2, p. 11



### In accordance with Section 3.2.1.3 of referen ce 1, the hazardous substance with the highest toxicity/mobility factor value is entered below and on line 4 of Table 3-1. This hazardous constituent is trichloroethene with a toxicity/mobility factor value of 10,000.

Toxicity/Mobility Factor Value: 10,000 (Reference 1, Table 3-9)

3.2.2 HAZARDOUS WASTE QUANTITY

Source No. Source Name Source Type Source Hazardous Waste Quantity



### 1 Ground Water Plume with no

identified Source Other Greater than Zero

Sum of Values: Greater than Zero

As described in the HRS Rule Section 2.4.2.2, if the hazardous constituent quantity is not adequately determined for one or more sources, assign a factor value as follows. If any target for the ground water migration pathway is subject to Level I or II concentrations, assign either the value from Table 2-6 (Ref. 1, Section 2.4.2.2, Table 2-6), or a value of 100, whichever is greater, as the hazardous waste quantity factor value for that pathway. Because the source hazardous waste quantity value is unknown but greater than zero, according to Table 2-6, the assigned factor value is 1. Ground water pathway targets are subject to actual contamination at Level I concentrations; therefore, the hazardous waste quantity factor value is assigned a value of 100 (Ref. 1 Section 2.4.2.2.). This value is entered on line 5

of HRS Table 3-1.

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

September 2011 GW – Waste Characteristics 35

### September 2011 GW – Waste Characteristics 36 

### 3.2.3 WASTE CHARACTERISTICS FACTOR CATEGORY VALUE

As specified in the HRS Rule (Ref. 1, Section 3.2. 3), the Hazardous Waste Quantity Factor Value of 100 was multiplied by the highest toxicity/mobility value of 10,000 for TCE, resulting in a product of 1,000,000 (1 x 10 6 

### ). Based on this product, a waste characteristics factor value (WCFV) of 32 was assigned from Table 2-7 of the HRS Rule (Ref. 1, Sec tion 2.4.3.1). This value is entered on line 6 of

HRS Table 3-1.

Toxicity/Mobility Factor Value: 10,000 Hazardous Waste Quantity Factor Value: 100 Product = 1,000,000 or 1 x 10 6



### Waste Characteristics Factor Category Value: 32 (Ref. 1, Table 2-7)

### 3.3 TARGETS

Targets considered include the four factors listed below; nearest well, population, resources and wellhead protection area (Ref. 1, Section 3.3). Population co nsiders those residents, students and workers who regularly use the water (Ref. 1, Section 3.3.2). As documented below, the population factor is calculated differently based on whether the water from the point of withdrawal is subject to actual or potential

contamination.

3.3.1 NEAREST WELL

Well ID: All private wells, except those listed as b ackground wells, presented in section 3.1.1 of this

documentation record contained TCE at concentr ations that exceeded one or more benchmark concentrations. These private wells include the fo llowing using designators devised by MDNR: MDNR 176, MDNR 168, MDNR 170, MDNR 102, MDNR 104, MDNR 118, MDNR 121, MDNR 117, MDNR 114, MDNR 124, MDNR 181, MDNR 251, and EPA samp le location 5049-15. The locations of these wells are shown on Figure 2 of this documentation reco rd. The locations of the wells sampled by MDNR are shown on Figure 5 of the SI/RSE report (Ref. 4, p. 45).

Level of Contamination (I, II, or potential): Level I

Thirteen private wells and two public wells meet th e criteria for an observed release subject to Level I concentrations. Since one or more ground water samp les from the private drinking water wells meet the criteria for an observed release subject to Level I concentrations, a Nearest well Factor Value of 50 has been assigned in accordance with section 3.3.1 of reference 1. This value is entered below and on line 7

of HRS table 3-1.

Nearest Well Factor Value: 50 (Ref. 1, Table 3-11)

3.3.2 POPULATION

3.3.2.1 Level of Contamination

The population served by water from a point of wit hdrawal may be evaluated based on the level of contamination for the point of withdrawal (Ref. 1, Section 3.3.2.1). Because previous sampling events indicate actual and potential target populations, the foll owing sections detail the respective target values. The 4-mile target distance limit (TDL) is shown below as Figure 3. Contaminated private wells sampled by MDNR are described in Section 4.2 of the SI/R SE report (Ref. 4, pp 22 – 24) and are shown on Figure 5 of the report (Ref. 4, p.45). Contaminated priv ate wells are also shown on Figure 2 of this

documentation record.

The City of Rogersville municipal water supply utili zes two deep wells that draw exclusively from the Ozark aquifer (Refs. 4, p. 22; 20). A map showi ng the water mains and municipal well locations is presented in the SI/RSE report (Ref. 4, p. 44). Outside the city limits, it is appa rent that privately owned community, non-community and private wells provide water to users (Ref. 4, pp. 22, 23, 41). State databases list 13 community and non-community public we lls and 557 private wells near the site (Ref. 4, p. 23; 8, pp. 9 – 28). Approximately 45 percent of the recorded wells have open boreholes connecting the Springfield Plateau and Ozark aquifers (Ref. 4, p. 23; 8 pp. 1, 2).

September 2011 GW – Targets 37

### Municipal well nos. 1 and 4 were sa mpled multiple times in 2010 and no TCE was ever reported (Ref. 4, pp. 26, 70-73, 100-103, 118-121, 132-133, 144-145, 148-151, 154-157). The Compass Plaza well and the well serving the Citizen’s Bank of Rogersville were also sampled multiple times in 2010 (Ref . 4, pp. 26, 28). These wells provided water to workers a nd student populations (Ref. 4, pp. 7, 24).

In March, April and September 2010, 121 private drinking water wells were sampled by MDNR (Ref. 4, p. 26). Some of these wells were sampled multiple times. Of the wells sampled, 12 contained concentrations of TCE, 1,1,2 TCA or cis-1,2-DC E (Ref. 4, pp. 24, 28, 29, 30). Reported TCE concentrations ranged from non-detect to 369 μ g/L (Ref. 4, pp. 28-30). In each well with TCE above the detection limit, concentrations of TCE exceeded the CRSC of 0.21 μ g/L for TCE (Ref. 2, p. 6). In five of the wells, concentrations were also above the MCL of 5 μ g/L for TCE (Ref. 2, p. 6; 4, pp. 28 – 30). One

well contained TCE concentrations above the NCRSC of 11 μ g/L (Ref. 2, p 6; 4, p. 29).

EPA Region 7 directed Tetra Tech START to sample the wells at the site in August 2010 in support of a removal action (Refs. 13, p. 1; 14). START samp led one well at 9243 East Farm Road 186 that had not previously been sampled by MDNR (Ref. 14, p 17). This well contained TCE at 4.4 μ g/L, above the

CRSC of 0.21 μ g/L (Ref. 2, p. 6; 15, p. 13). These wells are all the known wells to contain chlorinated solvents. Continuing investigations are ongoing to identify and sample new wells.

3.3.2.2 Level I Concentrations

Populations served by the private wells sampled by MDNR are provided in the SI/RSE report (Ref. 4, pp. 23, 24). For the well sampled by EPA with the sample number of 5049-15, population served by the well was obtained during a February 22, 2011 sampling event (Refs. 14, p. 17; 19, p. 10).

The Compass Plaza Well was constructed in 2004 and draws water from the Ozark aquifer (Ref. 4, p. 7). In the spring of 2009, the Graceland Daycare c onnected to the Compass Plaza well which changed the

wells status from a transient to a non-transient water supply (Ref. 4, p. 7). A non-transient noncommunity well is defined as a public water system that is not a community water system, and that regularly serves at least 25 of the same persons over six months per year (Ref. 4, p. 7). This non-transient system was assigned a public water system identification number (PWS ID) of MO5292838 (Ref. 4, p. 62). After TCE was detected in the well, the syst em was sampled multiple times and on September 29, 2010, the well was disconnected and connected to city wa ter (Ref. 4, pp. 7, 28, 1555). For the period the well was in service, a conservative estimate of 25 persons served is used for scoring (Ref. 4, pp. 7, 24).

The Citizen’s Bank of Rogersville well is a 545 feet deep, transient non-community well, and draws from the Ozark aquifer (Ref. 4, p. 7). Due to its proximity to the Compass Plaza well, the well was sampled by the PDWB on March 8 and 16, 2010 and was doc umented to contain TCE at 2.25 and 2.11 μ g/L (Ref. 4, pp. 7, 74, 75, 90, 91). Because the well is potentia lly used by transient pop ulations, only the worker population at the Bank will be used in scoring. It is assumed that at least one person may use the well on a daily basis.

September 2011 GW – Targets 38Level I Well Codes Aquifer No. Population Reference Compass Plaza Well Ozark Aqui fer - 2 25 4, pp. 7, 24 Citizen’s Bank of Rogersville Ozark Aquifer - 2 1 4, pp. 7, 24

102 Not specified 4 4, p. 24

114 Not specified 2 4, p. 24

251 Not specified 2 4, p. 24

118 Not specified 3 4, p. 24

176 Not specified 2 4, p. 24

EPA 5049-15 Not specified 4 14, p. 17; 19, p. 10

124 Not specified 1 4, p. 24

104 Not specified 3 4, p. 24

117 Not specified 3 4, p. 24

170 Not specified 2 4, p. 24

181 Not specified 2 4, p. 24

121 Not specified 2 4, p. 24

168 Not specified 2 4, p. 24 Total Level I targets 58



### In total, at least 58 targets are subject to Level I contamination. Because these populations are subject to contamination above a health based benchmark, the num ber of targets in multiplied by 10 as specified in Section 3.3.2.2 of the HRS rule (Ref . 1) to produce a Level I concentration factor value of 580. These

numbers are entered below and on line 8a of HRS Table 3-1.

Sum of Population Served by Level I Wells: 58 Sum of Population Served by Level I Wells x 10: 580

Level I Concentrations Factor Value: 580

3.3.2.3 Level II Concentrations

Level II population is not scored as all wells with actual contamination are subject to Level I

concentrations .

Level II Concentrations Factor Value: 0

3.3.2.4 Potential Contamination

Potential contamination targets for the ground wa ter migration pathway include all domestic and municipal ground water wells within 4 miles not subject to actual contamination at Level I or II concentrations (Ref. 1, Section 3. 3.2.4). Data regarding each of th e public and private drinking water wells found near the site, together with a figure s howing the location of each well is provided in the DGLS Hydrogeologic Report (Ref. 8). The DGLS databases contain records of three municipal wells (City of Rogersville wells) within 4 miles of the site (Ref. 8, pp. 9, 10; see also Figure 3 of this documentation record). Rogersville City Well #2 is only used for monitoring purposes (Ref. 4, p. 22). As shown of Figure 3 of this documentation record, th e two wells used for production (Wells #1 and #4) are located between 1 and 3 miles east northeast of the center of the ground water plume. They are both over 1,000 feet deep, drawing from the Ozark Aquifer, an d are cased completely through the Ozark Confining Unit (Refs. 4, p. 22; 20, p. 2).

September 2011 GW – Targets 39

### September 2011 GW – Targets 40 The most recent Census of Missouri Public Water Systems lists the population served by the City of Rogersville’s two public well as 1,500 (Ref. 4, p. 22 ). Based on communications with the City of Rogersville in November 2010, the well system serves 1,100 connections (Ref. 4, p. 1482). According to U.S. Census Bureau estimates, th e average household size in Rogersville is 2.7 people per household (Ref. 32). Based on these reported values, the total population served by the system is 2,970 (1,100 connections times 2.7 persons per household). A map showing the layout of the water lines in the system is provided as Figure 4 of the SI/RSE report (Ref. 4, p. 44). The proportion of the population served by each well (based on pumping capacity) is provided in the table below.

CITY OF ROGERSVILLE PUBLIC WELLS SYSTEM SUMMARY
Total Population. Served (persons) 2,970
Pumping Capacity Well#1 (gallons per minute) 180
Pumping Capacity Well#4 (gallons per minute) 350 Total Pumping Capacity (gallons per minute) 530
Proportion supplied by Well #1 (percent) 34
Proportion supplied by Well #4 (percent) 66
Pop Served by Well #1 (persons) 1,010
Pop Served by Well #4 (persons) 1,960

Source: Ref. 4, pp. 22, 23, 1482



### Figure 3 illustrates the 0.25-. 0.50-, 1.0-, 2.0-, 3. 0-, and 4.0-mile radius rings measure from the approximate center of the ground water plume. Only the municipal wells and the wells that serve the three public schools are included in the potential contamination scoring because they serve the greatest population.

Population served by the wells at the schools was est imated based on enrollment reported by the school district (Ref. 33). Reference 33 presents the appr oximate student population and is not believed to include staff. As a conservative estimate, only the student population was used in scoring.September 2011GW – Targets41Distance Category Municipal and Private Drinking

Water Wells Apportioned Population (Individuals) References Distance-Weighted Population Value (Ref. 1 Table 3-12)

0 to 0.25 Not scored Not scored

0.25 to 0.5 Not scored Not scored

0.5 to 1 Not scored Not scored

1 to 2 Rogersville well 1 1,010 4, pp. 22, 23, 45, 1482; 20; 32 294

2 to 3 Rogersville well 4 Logan-Rogersville Middle School

Logan-Rogersville High School

Total Population 2-3 miles 1,960

350

700 3,010 4, pp. 22, 23, 45, 1482; 20; 27; 28; 32, 33 678

3 to 4 Logan-Rogersville Primary

School 350 4, p. 45; 29; 33 42

Total 4,370 1,014



### Sum of Distance-Weighted Population Values: 1,014 Sum of Distance-Weighted Population Values/10: 101.4 rounded to 101

Potential Contamination Factor Value: 101

3.3.2.5 Calculation of Population Factor Value :

The total population factor value is the sum of the potential contamination factor (101), the Level I actual contamination factor (580), and the Level II actual cont amination factor (0)(Ref. 1, Section 3.3.5). The total population factor is 681 (580 Level I + 0 Level II + 101 potential).

3.3.3 RESOURCES

Ground water use as a resource as defined in Section 3.3.3 of reference 1 has not been evaluated.

Resources Factor Value: 0

3.3.4 WELLHEAD PROTECTION AREA

A designated Wellhead Protection Area for the Rogers ville public water supply system has been mapped within the 4-mile target distance limit (Ref. 20, p. 1). The maps provided in reference 20 are based on the

Missouri Source Water Assessment Plan which was deve loped to implement the requirements of the Safe Drinking Water Act Amendments of 1996 for state Source Water Assessment Programs [sections 1453 and 1428(b)] (Ref. 22, p. 1). In accordance with Section 3.3.4 of reference 1 a value of 5 is assigned and

entered below and on line 10 of HRS Table 3-1.

Wellhead Protection Area Factor Value: 5

September 2011 GW – Targets 42

### September 2011 GW – Targets 43 3.3.5 CALCULATION OF TARGETS FACTOR CATEGORY VALUE

The total targets factor category value is the sum of the nearest well, population, resources, and wellhead protection area (Ref. 1, Section 3.3.5). The total targets factor category value is 50 (nearest well) + 681 (population) + 0 (resources) + 5 (wellhead protection area) = 736. This value is entered on line 11 of

HRS Table 3-1.