Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

1

HAZARD RANKING SYSTEM (HRS) DOCUMENTATION RECORD

REVIEW COVER SHEET

SITE NAME: CIRCLE COURT GROUND WATER PLUME

CONTACT PERSON:

Documentation: Brenda Cook, USEPA 214/665-7436

Region 6 NPL Coordinator

Pathway, Components, or Threats Not Evaluated

Surface Water Pathway

The Surface Water Pathway was not scored because the inclusion of this pathway would not 

impact the listing decision.

Soil Exposure Pathway

The Soil Exposure Pathway was not scored because the inclusion of this pathway would not 

impact the listing decision.

Air Migration Pathway

The Air Migration Pathway was not scored because the inclusion of this pathway would not 

impact the listing decision.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

2

SITE DESCRIPTION

The Circle Court Ground Water Plume consists of a contaminated ground water plume 

originating from unknown sources composed of hazardous substances that released into the 

Paluxy formation of the Trinity aquifer. The plume location is delineated laterally by the 

ground water wells that had detections of trichloroethene (TCE) as listed in Table 1 and 

depicted in Figure 2.

The City of Willow Park and the City of Hudson Oaks supply water to most homes within 

the area of the site, except for some of the homes in the area of Russell Road. During the SI 

and ESI efforts, all domestic and public supply wells located within a quarter mile of the site 

and the majority of wells within a half mile of the site (Figure 2) were sampled. In addition 

all public supply wells within one mile of the site were sampled. The location of the plume 

is shown on Figure 2, and encompasses those well with documented observed releases of 

TCE concentration. 

The plume location was first indicated by a public water supply well at the Willow Springs 

Oaks Pump Station located at 117 Circle Court in Willow Park, Parker County, Texas, 

approximately 0.3 mile south of Interstate 20 and 0.3 mile west of Farm to Market Road 5 

(Annetta Road) (GW-05 on Figure 2). The pump station is in a rural residential area 

approximately six miles east of the City of Weatherford and is part of the City of Willow 

Park public water supply (PWS) system. Single-family properties border the pump station to 

the south, west and east. A 15-acre vacant wooded lot borders the pump station to the north. 

Three water system service pumps, two ground storage tanks and an elevated storage tank for 

water are also located at the Willow Springs Oaks Pump Station (Figure 2).

The City of Willow Park PWS is registered in the TCEQ PWS program and is assigned 

identification number 1840027 (Ref. 4, p. 1). The City of Willow Park’s PWS well located 

at 117 Circle Court in the Hillcrest addition is designated as GW-05 in Figure 2. The GW-05 

well depth is 180 feet (Ref. 5. p. 56, Well 3219201; Ref. 28, p. 7, Line 8; Ref 46 , p. 1).

Based on the combined results of the Site Inspection (SI) and Expanded Site Inspection (ESI) 

sampling events, the location of the plume roughly follows a one half mile stretch of Russell 

Road, with one detection of TCE further to the east, as listed in Table 1 and depicted in 

Figure 2. The highest concentration of TCE detected to date was 43 micrograms per liter 

(μg/L) in a domestic drinking water well, located at 405 Russell Road (Figure 2, GW-41, Ref 

39 p.5).
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

3

NOTES TO THE READER

The following rules were used when citing references in the Documentation Record:

1. Tracking numbers are assigned by the region to every page of every reference. The 

tracking number consists of the reference number followed by the page number within 

that reference. A tracking number will have a two-digit number followed by the 

sequential number (for example, 05 001; 05 002). The tracking numbers are cited for all 

references.

2. The State predecessor agencies: Texas Natural Resource Conservation Commission 

(TNRCC), Texas Water Quality Board (TWQB), Texas Department of Water Resources 

(TDWR), Texas Water Commission (TWC), and Texas Air Control Board (TACB), 

referred to throughout this report are now known as the Texas Commission on 

Environmental Quality (TCEQ). The new agency, TCEQ, became effective September 

1, 2002, as mandated under House Bill 2912, Article 18 of the 77th Regular Legislative 

Session.

3. List of Figures

Figure 1 Site Location Map

Figure 2 Ground Water Sample Location Map

Figure 3 Soil Sample Location Map

Figure 4a Surface Geology Map

Figure 4b Regional Geology and Aquifers

Figure 5 Drinking Water Wells by Distance Radii
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

4

HRS DOCUMENTATION RECORD

Name of Site: Circle Court Ground Water Plume

Date Prepared: March 2012

CERCLIS Site ID Number: TXN 000 606 965

Site Specific Identifier: A6V7

Street Address of Site*: 117 Circle Court.

City, County, State: Willow Park, Parker County, Texas 76087

General Location in the State:

The Circle Court Ground Water Plume’s location is the center of the plume, which is located 

approximately 0.4 mile south of Interstate 20 and 0.4 mile west of Farm to Market 5 (Annetta 

Road) (Figures 1 and 2). 

Topographic Map: U.S. Geological Survey 7.5 Minute Topographic Map, Lake 

Weatherford and Anneta Quadrangles.

Latitude*: 32.74477756o (North) Longitude: * -97.67976306o (West)

EPA Region: 6

Ground Water Pathway 100.00

Surface Water Pathway NS**

Soil Exposure Pathway NS**

Air Pathway NS**

HRS SITE SCORE 50.00

*The street address coordinates, and contaminant locations presented in this Hazard Ranking System (HRS) documentation 

record identify the general area in which the site is located. They represent one or more locations that the U.S. 

Environmental Protection Agency (EPA) considers to be part of the site based on the screening information EPA used to 

evaluate the site for National Priority List (NPL) listing. EPA lists national priorities among the known "releases or 

threatened releases" of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is 

defined as where a hazardous substance has been "deposited, stored, placed, or otherwise come to be located." Generally, 

HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to 

be addressed under the Comprehensive Environmental Response, Compensation, and Recovery Act (CERCLA). 

Accordingly, EPA contemplates that the preliminary description of facility boundaries at the time of scoring will be refined 

as more information is developed as to where the contamination has come to be located.

**NS=Not Scored (Pathways were evaluated but not scored because their evaluation would not effect the listing decision.)
μ

Circle Court 

Groundwater Plume

Parker County, Texas

TXN000606965

2!!

City of Weatherford 

Six miles to the west

Circle DriveCircle Court

Site Center

Mikus

Bankhead

Fort Worth

180

Farm

To

Market

Lakeshore

Stage Coach

20 Access Rd

Mikus

§ ̈¦20 £¤180

UV5

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2

Miles

This map was generated by the Remediation Division of the Texas

Commission on Environmental Quality. It is intended for illustrative

or informational purposes only, and is not suitable for legal, 

engineering, or survey purposes. This map does not represent an

on-the-ground survey conducted by or under the supervision of a

registered professional land surveyor. In cases where property

boundaries are shown, it only represents their approximate relative

location. No claims are made to the accuracy or completeness of the 

data or to its suitability for a particular use. For more information 

concerning this map, contact the Remediation Division at 800-633-9363.

Figure 1: Site Location Map

The base data set is UTM Zone 14, Digital Raster Graphics of the Lake Weatherford and Anneta Quadrangles, NAD 1983 

Parker County
Kingswood

Ranch Oak

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I 20 

Bankhead Mikus 

Interstate 20 

Crown 

Russell 

Interstate 20 Service 

Fork 

Fort Worth 

Lakeshore 

Rob 

Arroyo 

Coates 

Big Creek 

Red Bud 

Oak Hill 

Dorris

Mallory 

Southview 

FM Road 5 

Valley 

Diamond Oaks 

Raven 

McKinzie 

Bluebonnet

Elm Tree 

Walters 

Valley Trail 

Austen 

Oak Park 

Megan 

Live Oak 

Clear Fork 

Bond 

Hunterglenn 

Red Oak 

Park 

Cottonwood 

Woodridge 

Green Oaks 

Primrose

Pecan Park 

Oak Leaf

Beech 

Walkers 

Wintergreen 

Derek 

Steeple Chase 

Brookview 

Saddle Brook 

Hawthorne 

Kate 

Meadowview 

White Oak 

I 20 

Fort Worth 

Interstate 20 

Interstate 20 

GW-01/

GW-02
 

GW-31 Tackett(Background)!.

GW-50!. 

!. GW-49 

!.
 

GW-03 !.
 GW-04/DUP GW-25
 

GW-38/DUP GW-39 

GW-42 !. 

Parker Oaks 

GW-06

GW-41 (Site Center) 

!. GW-22
 !.

GW-45

GW-34/

/

GW-11/

DUP GW-46 

GW-07 / DUP GW-08 

DUP GW-35 

!. 

GW-44
 

GW-47 !.
 

!.
 

GW-10

GW-33 Oakview 

GW-37 

GW-20 

GW-43 

DUP GW-09 

GW-05 

GW-14

GW-12 

GW-16/

w

GW-40 llo oHakO

!. 

!. 

!. 

!. 

!. !. GW-19/DUP GW-18
 

Figure 2: Groundwater Sample Location Map
 

μ 

Circle Court

Groundwater Plume

Parker County, Texas

TXN000606965
 !.
 !. GW-36
 

/

!. 

!.
 !. 

!.
 

GW-48
 

Legend

Groundwater Sample Location 

Level 1 Concentration 

Potential Contamination 

!.

!.

!. 

!.
 

GW-15/GW-32 (

!.

Background) 

Parker County Peach 

!.

!. !. 

This map was generated by the Remediation Division of the Texas

Commission on Environmental Quality. It is intended for illustrative 

or informational purposes only, and is not suitable for legal,

engineering, or survey purposes. This map does not represent an

0	 0.25 0.5 0.75 1 1.25 1.5 1.75 2 on-the-ground survey conducted by or under the supervision of a 

registered professional land surveyor. In cases where property

Miles boundaries are shown, it only represents their approximate relative

location. No claims are made to the accuracy or completeness of the

data or to its suitability for a particular use. For more information The base data set is UTM Zone 14, 0.5 Meter Resolution, Natural Color, NAD 1983	 concerning this map, contact the Remediation Division at 800-633-9363. 

DUP GW-17 !.
 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

7

WORKSHEET FOR COMPUTING HRS SITE SCORE

S S2

1. Ground Water Migration Pathway Score (Sgw) 100 10,000

(from Table 3-1, line 13)

2a. Surface Water Overland/Flood Migration 

Component (from Table 4-1, line 30)

NS

2b. Ground Water to Surface Water Migration 

Component (from Table 4-25, line 28)

NS

2c. Surface Water Migration Pathway Score (Ssw)

Enter the larger of lines 2a and 2b as the

NS

pathway score.

3. Soil Exposure Pathway Score (Ss)

(from Table 5-1, line 22)

NS

4. Air Migration Pathway Score (Sa)

(from Table 6-1, line 12)

NS

5. Total of Sgw

2 + Ssw2 + Ss2 + Sa2 10,000

6. HRS Site Score Divide the value on line 5 

 by 4 and take the square root. 50.00

NS = Not Scored
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

8

TABLE 3-1

GROUND WATER MIGRATION PATHWAY SCORESHEET

Factor Categories and Factors Maximum Value Value Assigned

Likelihood of Release to an Aquifer

1. Observed Release 550

2. Potential to Release

550

2a. Containment 10

2b. Net Precipitation 10

2c. Depth to Aquifer 5

2d. Travel Time 35

2e. Potential to Release

(Lines 2a(2b + 2c + 2d)) 500

3. Likelihood of Release

(Higher of Line 1 and 2e) 550 550

Waste Characteristics

4. Toxicity/Mobility *

5. Hazardous Waste Quantity

1,000

*

6. Waste Characteristics

100

100 18

Targets

7. Nearest Well 50

8. Population:

50

8a. Level I Concentrations **

8b. Level II Concentrations

2,875.3

** 0

8c. Potential Contamination **

8d. Population (Lines 8a + 8b + 8c)

113

**

9. Resources

2,988.3

5 0

10. Wellhead Protection Area 20 0

11. Targets (Lines 7 + 8d + 9 + 10) ** 3,038.3

Ground Water Migration Score for an Aquifer

12. Aquifer Score

((Lines 3 x 6 x 11)/82,500) 100 100

Ground Water Migration Pathway Score

13. Pathway Score (Sgw), (Highest value from Line 12 for all 

aquifers evaluated)

100 100
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

9

REFERENCE LISTING

Reference

1. U.S Environmental Protection Agency. Federal Register – 55 FR Page 51532; 

Hazard Ranking System; Final Rule, Volume 55, No. 241, December14, 1990. 137 

pages.

Number Description of the Reference

2. U. S. Environmental Protection Agency. Superfund Chemical Data Matrix (SCDM), 

Superfund Chemical Data Matrix. Appendix B. November 29, 2011. 7 excerpted 

pages. A complete version of SCDM is available at:

http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm

3. U.S.G.S 7.5-Minute Series Topographic Map. Anneta and Lake Weatherford 1959, 

photorevised 1979. Total Pages:2

4. City of Willow Park, City of Hudson Oaks, City of Willow Park Dyegard, Oak Hill 

Mobile Home Park East, Available: 

http://www10.tceq.state.tx.us/iwud/reports/index.cfm?fuseaction=RunWSDataSheetr

eport&RequestTimeout=500&pwsid=. Enter pws. Accessed September 15-16, 2011. 

28 pages.

5. Texas Water Development Board. Groundwater Database Reports. Record of Wells, 

Parker County. Available: 

http://www.twdb.state.tx.us/publications/reports/GroundWaterReports/GWDatabaseR

eports/Database%20Reports/Parker/Record%20of%20Wells.pdf. Accessed February 

1, 2011. 72 pages. 

6. City of Willow Park. Willow Springs Oaks TCE Removal. March 23, 2006. 1 page.

7. Agency for Toxic Substances and Disease Registry. ATSDR ToxFAQs Factsheet: 

Trichloroethylene CAS # 79-01-6. Available: http://www.atsdr.cdc.gov/tfacts19.pdf. 

July, 2003. Accessed February 22, 2011. 2 pages.

8. Eagle Construction & Environmental Services, L.P. Water Well Sampling Event. 

June 2006. 16 pages.

9. U.S. Environmental Protection Agency. Circle Court Groundwater Site Inspection 

Report. July 2011. 45 pages.

10. Texas Commission on Environmental Quality. Site Inspection Field Logbook Notes 

from Circle Court Ground Water. March 9-11, 2010. 56 pages.

11. Texas Commission on Environmental Quality. Site Investigation Photographs from 

Circle Court Groundwater. March 9-11, 2010. 21 pages.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

10

12. U.S. Environmental Protection Agency. Circle Court Groundwater Expanded Site 

Inspection Report. August 2011. 36 pages.

13. Texas Commission on Environmental Quality. Expanded Site Inspection Field 

Logbook Notes from Circle Court Groundwater. June 22-24, 2010. 45 pages.

14. Texas Commission on Environmental Quality. Expanded Site Inspection Photographs 

from Circle Court Groundwater. June 22-24, 2010. 9 pages.

15. U.S. Environmental Protection Agency. Evaluating Ground Water Plumes Under the 

Hazard Ranking System, EPA 540-F-95-034, OSWER Publication 9320.8-01FS, 

September 1998. 5 pages.

16. Texas Commission on Environmental Quality. Quality Assurance Project Plan for 

Texas Commission on Environmental Quality-Preliminary Assessment and Site 

Inspection Program (Number V-96665501-0). February 1, 2010. 225 pages.

17. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Health and Safety Plan. May 4, 2010. 29 excerpted pages.

18. U.S. Environmental Protection Agency Region 6 Laboratory. Final Analytical Report: 

Circle Court Groundwater. April 16, 2010. 83 pages.

19. U.S. Environmental Protection Agency Region 6 Laboratory. Final Analytical Report: 

Circle Court Groundwater. May 17, 2010. 8 pages.

20. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 39551, SDG#MF3FX7. March 26, 2010. 38 

pages.

21. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 39551, SDG#F3FY1. March 24, 2010. 98 

pages.

22. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 39551, SDG#F3FY0. March 26, 2010. 58 

pages.

23. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 39551, SDG#F3FX7. March 26, 2010. 303 

pages.

24. U.S. Environmental Protection Agency Methodology for Determining Screening 

Concentration Benchmarks for Trichloroethylene (TCE). Available: 

http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm. February, 2012. 12 

pages.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

11

25. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 40275, SDG#F3JJ4. July 19, 2010. 109 

pages.

26. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 40275, SDG#F3JK9. July 15, 2010. 29 

pages.

27. U.S. Environmental Protection Agency Region 6. Contract Laboratory Program Data 

Review: Circle Court Groundwater, Case 40275, SDG#MF3JJ4. July 29, 2010. 42 

pages.

28. Weston Solutions, Inc. Drinking Water Survey Report. May 2010. 129 pages 

including attachments.

29. Texas Commission on Environmental Quality. Site Inspection Work Plan, Circle 

Court Groundwater, Prepared in Cooperation With the U.S. Environmental Protection 

Agency. February 2010. 33 pages.

30. Texas Parks and Wildlife. Natural Subregions of Texas. January 31, 2011. 

Available: 

http://www.tpwd.state.tx.us/publications/pwdpubs/media/pwd_mp_e0100_1070x_08.

pdf. Accessed April 7, 2011. 1 page.

31. Texas Department of Water Resources. Report 269, Occurrence, Availability, and 

Chemical Quality of Ground Water in the Cretaceous Aquifers of North-Central 

Texas, Volume 1. Phillip L. Nordstrom. April 1982. 67 pages. 

32. The University of Texas at Austin, Bureau of Economic Geology. Geologic Atlas of 

Texas, Dallas Sheet. J. H. McGowen, C. V. Proctor, Jr., W. T. Haenggi, D. F. Reaser, 

and V. E. Barnes. Gayle Scott Memorial Edition. 1972; revised 1987; reprinted 2000. 

12 pages.

33. Texas Water Development Board. Report 345. Aquifers of Texas. John B. 

Ashworth, Geologist and Janie Hopkins, Geologist. November 1995. 69 pages.

34. Upper Trinity Groundwater Conservation District. District Management Plan. 

Adopted-8/16/2010. 156 pages.

35. Freese and Nichols, Inc., Alan Plummer Associates, Inc., CP&Y, Inc., Cooksey 

Communications, Inc. 2011 Region C Water Plan. October 2010. 123 pages.

36. Warren, Christy. U.S. Environmental Protection Agency, Region 6 Laboratory, 

Sample Control Center. Email to Brenda Nixon Cook, U.S. Environmental 

Protection Agency, Region 6 NPL Coordinator. August 6, 2010. 2 pages.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

12

37. US Census Bureau. Parker County QuickFacts. Available: 

http://quickfacts.census.gov/qfd/states/48/48367.html. Accessed September 27, 2011. 

2 pages.

38. Johnson, Lloyd. Texas Commission on Environmental Quality - Quality 

Assurance/Technical Support. Interoffice Memorandum: Data Quality Audit and 

Review. May 4, 2010. 6 pages.

39. Strahl, Ann. Texas Commission on Environmental Quality - Quality 

Assurance/Technical Support. Interoffice Memorandum: Data Quality Audit and 

Review. August 12, 2011. 7 pages.

40. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Telephone conversation with City of Willow Park Water Superintendent Devon 

Kennedy. August 10, 2011. 1 page.

41. Texas Commission on Environmental Quality. Expanded Site Inspection Work Plan, 

Circle Court Groundwater, Prepared in Cooperation With the U.S. Environmental 

Protection Agency. June 2010. 28 pages.

42. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Telephone conversation with City of Willow Park Water Superintendent Devon 

Kennedy. November 9, 2011. 1 page.

43. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Telephone conversation with City Hudson Oaks Water Superintendent Ricky King. 

November 17, 2011. 1 page.

44. Texas Water Development Board. LP-212. Delineation Criteria for the Major and 

Minor Aquifer Maps of Texas. John B. Ashworth, Geologist and Robert R. Flores, 

Geologist. June 1991. 25 pages.

45. Northern Trinity / Woodbine Aquifer Groundwater Availability Model. Assessment 

of Groundwater Use in the Northern Trinity Aquifer Due to Urban Growth and 

Barnett Shale Development. TWDB Contract Number: 0604830613. R. W. Harden 

& Associates, Inc. January 2007. 276 pages.

46. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Telephone conversation with City of Willow Park Water Superintendent Devon 

Kennedy. February 2, 2012. 1 page.

47. Hazelwood, Gary. Texas Commission on Environmental Quality Project Manager. 

Telephone conversation with City Hudson Oaks Water Superintendent Ricky King. 

February 2, 2012. 1 page.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

13

SOURCE DESCRIPTION

2.2 Source Characterization

2.2.1 Source Identification

Number of the source: 1

Name and description of the source: Other – Ground Water Plume with No Identified Source

On March 23, 2006, during routine monitoring of the City of Willow Park PWS, a volatile 

organic compound (VOC), trichloroethene (synonym: trichloroethylene, TCE), was detected 

at 6.9 μg/L (Ref. 6, p. 1). The detection exceeded the EPA maximum contaminant level

(MCL) for drinking water of 5 μg/L (Ref. 2, p. 6). Trichloroethene, a colorless organic liquid 

with a chloroform-like odor, is commonly used as a solvent to remove grease from metal 

parts and is not thought to occur naturally in the environment (Ref. 7, p. 1). The water 

sample that exceeded the MCL had been collected from the distribution system point of entry 

(POE) for the City of Willow Park’s Circle Court well (GW-05). As a result of the TCE 

exceedance in raw water at the Circle Court PWS Well, the well was taken out of service on 

April 1, 2006 (Ref. 6, p. 1). During subsequent VOC monitoring conducted by the City of 

Willow Park, a May 4, 2006 sample collected directly from the PWS Circle Court Well had a 

TCE concentration of 33.9 μg/L. On June 19, 2006, the City of Willow Park installed an 

inline filter on the impacted well, and the well was subsequently put back into service (Ref 5, 

p. 56-well number 3219201; Ref. 6, p. 1).

On June 1-2, 2006, as a follow-up to the TCE detection in the City of Willow Park’s Circle 

Court Well, the TCEQ sampled nine private wells in the vicinity of the well to determine if 

the private wells were impacted (Ref. 8, p. 5). The water samples were analyzed for 

concentrations of VOCs in drinking water by a drinking water certified laboratory. A review 

of the sample results indicated the presence of TCE in five of the nine private wells sampled. 

One of the five wells was a private non-drinking water well located at the Parker County 

Airport; the concentration of TCE reported for this well was 12.2 μg/L (Ref. 8, pp. 7 and 12 –

Barnett #2 well).

During the week of March 8, 2010, the TCEQ conducted an SI field sampling event for the 

TCE-contaminated ground water plume site (Ref. 9). The TCEQ collected six soil samples,

collected from a depth of 0-6 inches, including two background samples, one field duplicate,

and three soil samples to investigate the most likely potential source locations in the vicinity 

of the City of Willow Park’s Circle Court Well (Ref. 10, pp. 47, 49, 51, 53, and 55; Ref. 11, 

pp. 19-21, Ref. 29 pp.23-26). No TCE was detected in any of the soil samples (Ref. 9, p. 41). 

The TCEQ collected 19 ground water samples, including three background samples and three 

field duplicate samples (Ref. 9, pp. 16-17; Ref. 10, pp. 3-43; Ref. 11, pp. 1-19). Three 

aqueous field blank samples were also collected. The locations sampled by TCEQ included 

five public supply wells and eight private residential wells in the vicinity of the City of 

Willow Park’s Circle Court Well. Five wells were documented by chemical analysis to have 

TCE levels that met the observed release criteria and exceeded the cancer risk health-based 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

14

benchmark of 0.21 μg/L (Ref. 2, p. 6, Ref. 24, pp. 4-6 & 12). Three of those five wells were 

documented by chemical analysis to have TCE concentrations exceeding the MCL for 

drinking water of 5 μg/L, as listed in Table 7. One of the three wells exceeding the MCL 

was a non-drinking water well, but was still used to indicate the plume location in Figure 2.

The ESI field work was conducted during the week of June 21, 2010 (Ref. 12, p 16). The 

TCEQ collected 20 ground water samples, including two background samples, three field 

duplicate samples, one public supply well, and 14 private wells (Ref. 13; Ref. 14). The well 

locations were selected to complete the analysis of all known wells located within 0.25 mile

of the City of Willow Park Well’s Circle Court well, plus additional wells within 0.5 mile of 

the City of Willow Park’s Circle Court Well (Figure 2 – GW-05). Three aqueous field blank 

samples were also collected. Three wells were documented by chemical analysis to have 

TCE levels in excess of the cancer risk health-based benchmark of 0.21 μg/L with one well 

having been resampled from the SI sampling event (Ref. 2, p. 6, Ref. 24, pp. 4-6 & 12). One

of those three wells was documented by chemical analysis to have a TCE concentration 

exceeding the MCL for drinking water of 5 μg/L (See Table 8 of this HRS document). GW11 and GW-33 are samples collected on different dates, from the same well (Ref. 10, p. 29; 

Ref. 11, p. 10; Ref. 13, p. 7; Ref. 14, p. 1; Ref. 21, pp. 16,32&57; Ref. 25, pp. 12,31&41; 

Ref. 28, p. 7).

The combined SI and ESI sampling events resulted in a total of seven wells with observed 

releases (Figure 2, GW04 (Ref. 22, pp. 14,18,26&35), GW-05 (Ref. 21, pp. 10,28&39), GW10 (Ref. 21, pp. 15,31&54), GW-12 (Ref. 22, pp. 12,19&29), GW-33 (Ref. 39, pp. 1-7), GW41 (Ref. 39, pp. 1-7), and GW-48 (Ref. 39, pp. 1-7)). Of the seven wells with observed 

releases, three drinking water wells had documented levels of TCE exceeding the MCL

(Figure 2, GW05 (Ref. 21, pp. 10,28&39), GW-10 (Ref. 21, pp. 15,31&54), and GW-41

(Ref. 39, pp. 1-7)); each of these drinking water wells either has a granular activated carbon 

filtration system or in the case of GW-10 a system was provided and later removed at the 

resident's request. All three of these wells are located in close proximity of Russell Road and 

are screened in the Paluxy formation of the Trinity aquifer, which is the primary drinking 

water aquifer in the area. Some residences in the vicinity of the site depend on private water 

wells screened in the Paluxy formation of the Trinity aquifer as their primary drinking water 

source. The highest level of TCE was found in a private domestic drinking water well 

located at 405 Russell Road, Willow Park (Figure 2, GW-41 (Ref. 39, pp. 1-7)). One nondrinking water well, located at the Parker County Airport, (Figure 2, GW-04), was also

documented to have a TCE level exceeding the MCL (Ref. 22, pp. 14,18,26&35).

The ground water plume is considered the source, since no surface sources were identified 

through soil sampling or reconnaissance of nearby areas (Ref. 1; Section 1.1; Ref. 9, pp. 37-

39; Ref. 12, p. 30). 

The ground water plume with no identified source was characterized as the site source based 

on the following:

• The extent of the plume was estimated solely by sampling, using the criteria for an 

observed release to the Ground Water Migration Pathway (Ref. 1, Section 2.2; See 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

15

Table 11). The City of Willow Park and the City of Hudson Oaks supply water to 

most homes within the area of the site, except for some of the homes in the area of 

Russell Road. During the SI and ESI efforts, all domestic and public supply wells 

located within a quarter mile of the site and the majority of wells within a half mile of 

the site (Figure 2) were sampled. In addition all public supply wells within one mile 

of the site were sampled (Ref. 10, pp. 16-18; Ref 12, pp. 17-19). The location of the 

plume is shown on Figure 2, and encompasses those well with documented observed 

releases of TCE concentration. 

 

• The level of effort to identify the original source(s) of the hazardous substances by an 

SI conducted March 9 – 11, and an ESI conducted June 22 – 24, 2010 (Ref. 10, pp. 

17,27,29&43; Ref. 11, pp. 4,5,9,10,18&19; Ref. 13, pp. 11&45; Ref. 14, pp. 3&9; 

Ref. 15, p. 2) is discussed in the Possible Sources Section on page 20 of this 

documentation record. 

See Figure 2, Groundwater Sample Location Map.

Location of the source, with reference to a map of the site:

Other - Ground Water Plume with No Identified Source.

Source type for HRS evaluation purposes:

Gas release to air: The air migration pathway was not evaluated; therefore, gas containment 

was not evaluated.

Containment

Particulate release to air: The air migration pathway was not evaluated; therefore, particulate 

containment was not evaluated.

Release to ground water: The Containment Factor Value for the ground water migration 

pathway was evaluated for “All Sources” for evidence of hazardous substance migration 

from source area (i.e., source area includes source and any associated containment 

structures). The applicable containment factor value was determined based on existing 

analytical evidence of hazardous substances in ground water samples from private and public 

wells (documented releases are listed and referenced in Table 1). Therefore, based on no 

liner and evidence of a release, the highest Ground Water Migration Pathway Containment 

Factor Value of 10 was assigned to Source No. 1 as specified in Table 3-2 of the HRS (Ref. 

1, Section 3.1.2.1).

Release to surface water overland/flood migration component: The surface water pathway 

was not scored; therefore, surface water overland/flood migration component containment 

was not evaluated.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

16

2.2.2 Hazardous Substances Associated With A Source

The ground water plume with no identified source, Source 1, contains measured levels of 

trichloroethene, for which observed releases were established within the Paluxy formation of 

the Trinity aquifer, the aquifer being evaluated for the Ground Water Migration Pathway. 

Trichloroethene was detected above the background level in samples collected by the TCEQ 

in 2010, including both the SI and ESI, tasked to the TCEQ by the USEPA, which are given 

in Table 1 below. All field work was conducted as outlined in the work plan, including the 

Expanded Site Inspection Health and Safety Plan (HASP), and the TCEQ/EPA approved 

Quality Assurance Project Plan (QAPP) for TCEQ Preliminary Assessment/Site Inspection 

Program: Federal Grant Identification Number V-96665501-0 (Ref. 16; Ref. 17; Ref. 29; Ref. 

41). All deviations from the work plan and/or QAPP were noted in the field notebooks (Ref. 

10; Ref. 13). The laboratories that tested the samples for the Circle Court Ground Water 

Plume were:

• US EPA Region 6 Laboratory, 10625 Fallstone Road, Houston, Texas 77099 (Ref. 

18; Ref. 19; Table 7)

• ChemTech Consulting Group, 284 Sheffield Street, Mountainside, New Jersey 07092 

(Ref. 20; Table 7)

• A4, The Woodlands, Texas – 1544 Sawdust Road, Suite 505, The Woodlands, Texas 

77380 (Ref. 21; Ref. 22; Ref. 23; Ref. 27; Tables 7 and 8)

• Mitkem Corporation, Warwick, Rhode Island – 175 Metro Center Boulevard, 

Warwick, RI 02886 (Ref. 25; Ref. 26; Table 8)

Tap water samples collected closest to the wells prior to treatment were analyzed by method 

CLP SOM01.2, for organic drinking water analysis and method CLP ISM01.2, for inorganic 

drinking water analysis (See Table 1; Table 7; and Table 8). The analytical results 

documented the organic compound trichloroethene greater than or equal to the background 

sample(s) quantitation limit, if not detected in background samples (see Tables 7 and 8).

Not all of the depths for the water wells are specified due to lack of information known by 

the well owners. According to a Drinking Water Survey Report, the wells with documented 

well depths are typically screened between 100 and 250 feet below ground surface, which 

draws from the Paluxy Formation of the Trinity Aquifer (Ref. 5, p. 56). For the purpose of 

this record, only those wells installed in the Paluxy formation of the Trinity aquifer were 

included in the Ground Water Migration Pathway Score.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

17

Table 1: Sample Collection for Source 1 –

Other (Ground Water Plume with No Identified Source)

Note: TCE was not detected in any of the background wells, during either the SI or ESI. Background 

wells are listed in Tables 5 and 6

Well 

ID*

Sample 

Location/Event

Well Depth (feet) Date 

Collected

TCE

Detection 

Level

In μg/L

Reference

GW-04 Non-Drinking Water 

Well at Parker Co. 

Airport

Not Specified, but 

from the Paluxy 

Formation of the 

Trinity Aquifer (Ref. 

5, p. 56)

3/11/10 5.4 Ref. 10, p. 37; Ref. 11, 

pp. 13-17; Ref. 16; Ref. 

22, pp. 11,18 &26; Ref. 

29, p. 19; Ref. 38, pp. 

1-6 

GW-25 3/11/10 5.4 Ref. 10, p. 37; Ref. 11, 

pp. 13-17; Ref. 16; Ref. 

22, pp. 14,18&35; Ref. 

29, p. 18; Ref. 38, pp. 

1-6

GW-05 PWS 117 Circle 

Court Willow Park 

Municipal System’s 

Well #20

240

(Ref. 4, p. 10)

3/9/10 6.5 Ref. 10, p. 17; Ref. 11, 

pp. 4 & 5; Ref. 16; Ref. 

21, pp. 10,28& 39; Ref. 

29, p. 18; Ref. 38, pp. 

1-6

GW-10 Drinking water well 

at 546 Russell Road 

180-200

(Ref. 28, p. 7)

3/10/10 10 Ref. 10, p. 27; Ref. 11, 

p. 9; Ref. 16; Ref. 21, 

pp. 15,29&54; Ref. 29, 

p. 19; Ref. 38, pp. 1-6 

GW-11 Drinking water well 

at 550 Russell Road 

280; Screened 100-

280 (Ref. 28, p. 7)

3/10/10 2.5 Ref. 10, p. 29; Ref. 11, 

p. 10; Ref. 16; Ref. 21, 

pp. 16,32&57; Ref. 29, 

p. 19; Ref. 38, pp. 1-6 

GW-33 6/22/10 3.8 Ref. 13, p. 7; Ref. 14, p. 

1; Ref. 16; Ref. 25, pp. 

11,31&33; Ref. 41, p. 

15; Ref. 39, pp. 1-7

GW-12 Drinking water well 

at 108 Circle Drive 

Not Specified, but 

from the Paluxy 

Formation of the 

Trinity Aquifer (Ref. 

5, p. 56)

3/11/10 1.3 Ref. 10, p. 43; Ref. 11, 

pp. 18 & 19; Ref. 16; 

Ref. 22, pp. 12,19&29; 

Ref. 29, p. 19; Ref. 38, 

pp. 1-6

GW-41 Drinking water well 

at 405 Russell Road 

200; screened 160-

194

(Ref. 28, p. 7)

6/22/10 43 Ref. 13, p. 11; Ref. 14, 

p. 3; Ref. 16; Ref. 25, 

pp. 20,31&68; Ref. 41, 

p. 15; Ref. 39, pp. 1-7

GW-48 Drinking water Well 

at 179 Annetta Road 

Not Specified, but 

from the Paluxy 

Formation of the 

Trinity Aquifer (Ref. 

5, p. 56)

6/24/10 2.7 Ref. 13, p. 45; Ref. 14, 

p. 9; Ref. 16; Ref. 26, 

pp. 8,12&16; Ref. 39, 

pp. 1-7; Ref. 41, p. 16.

Note:

* Some sample locations have multiple Sample IDs. However, the multiple Sample IDs correspond to the same sample location. The 

multiple Sample ID numbers are due to use of different Sample IDs during different sampling events at those sampling locations.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

18

2.2.3 Hazardous Substances Available to a Pathway

The containment factor value for Source 1 is 10 (see Containment in Section 2.2.1 of this 

documentation record). The following hazardous substances associated with the ground 

water plume source can migrate via the ground water pathway:

Table 2: Hazardous Substance Available to a Pathway

Hazardous 

Substances

Air Pathway Ground 

Water

Surface Water Soil Exposure

Gas Particulate Overland/

Flood

GW to 

SW Resident Nearby

Trichloroethene NS NS Y NS NS NS NS

Notes and Qualifiers:

NS = Not Scored

Y = Yes
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

19

2.4 Waste Characteristics

2.4.2 Hazardous Waste Quantity

2.4.2.1 Source Hazardous Waste Quantity

2.4.2.1.1 Hazardous Constituent Quantity (Tier A) – Not Evaluated (NE)

The information available is not sufficient to evaluate Tier A as required in Section 2.4.2.1.1 

of the HRS, which is to determine total mass of the hazardous substance present in the waste 

source. The lack of manifests detailing waste quantities does not support the use of Tier A. 

The mass of all the hazardous substances has not been determined as a result, the evaluation 

of Hazardous Waste Quantity proceeds to the evaluation of Tier B, hazardous wastestream

quantity (Ref. 1, Section 2.4.2.1.1).

2.4.2.1.2 Hazardous Wastestream Quantity (Tier B) - NE

There is not sufficient information to evaluate Tier B which requires determining mass of the 

hazardous wastestreams that are allocated to the source as required in the HRS (Ref. 1, 

Section 2.4.2.1.2). Because the original source of contamination is unknown, the hazardous 

wastestream quantity cannot be calculated and the evaluation of Hazardous Waste Quantity 

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

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 HRS Table 2-5 (Ref. 1, Section 2.4.2.1.3). The hazardous waste 

quantity for a plume site with no identified source can be determined by measuring the area 

within all observed release samples combined with the vertical extent of contamination to 

arrive at an estimate of the plume volume (Ref. 15, p. 4).

However, the lack of the vertical extent of contaminant delineation prohibits an exact volume 

concentration. The presence of contaminated ground water samples shows that the volume is 

greater than zero. Therefore, the volume of the ground water plume is assigned a volume 

hazardous waste quantity value greater than (>) 0. The value of >0 reflects that the volume is 

known to be greater than 0, but the exact amount is unknown.

2.4.2.1.4 Area (Tier D)

Since the volume of greater than zero was assigned to the Tier C, the area (Tier D) is not to 

be evaluated and instead, assigned a value of 0 (Ref. 1; Section 2.4.2.1.3). 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

20

2.4.2.1.5 Source Hazardous Waste Quantity Value

As described in the HRS, the highest value assigned to a source from among the four tiers of 

hazardous constituent quantity (Tier A), hazardous waste stream quantity (Tier B), volume 

(Tier C) or area (Tier D) was selected as the source hazardous waste quantity value (Ref. 1, 

Section 2.4.2.1).

Table 3: Source Hazardous Waste Quantity Source No. 1, Other – Ground Water 

Plume with No Identified Source

Tier Measure Migration Pathway (Ground Water)

Tier A, Constituent Quantity NE

Tier B, Wastestream Quantity NE

Tier C, Volume > 0

Tier D, Area 0

NE = Not Evaluated

Source No. 1, Other – Ground Water Plume with No Identified Source, Hazardous 

Waste Quantity Value: > 0
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

21

SOURCE SUMMARY

The TCEQ conducted sampling activities at the Circle Court Ground Water Plume during 

2010. Thirty-three wells were sampled by the TCEQ during 2010, sixteen wells were 

sampled during the March 2010 SI and seventeen wells were sampled during the June 2010 

ESI (Ref. 9; Ref. 12). The source hazardous waste quantity and containment for the site is 

summarized in the table below.

Table 4: Source Summary

Source 

Number

Source Hazardous 

Waste Quantity 

Value

Containment

Ground 

Water Surface Water Soil Exposure Gas Air Particulate

1 > 0 10 NE NE NE NE

TOTAL > 0

NE = Not Evaluated

POSSIBLE SOURCES

The site is designated as a trichloroethene-contaminated ground water plume originating 

from an unknown source or sources. A limited number of potential sources of TCE are 

located within a half mile of the site. The area of the site is rural residential with very little 

commercial activity in the area. Wells with no detection of TCE are located between each 

commercial business and the site. TCE may have been used as a degreasing agent for metal 

parts. During the SI, soil sample locations were selected that appeared to be the most likely 

locations to detect TCE, from the most likely potential sources. The SI Work Plan included

ten soil samples to be collected, but during the SI soil sampling event, the number of soil 

samples was reduced, since the only known likely potential sources were the Parker County 

Airport and a lawnmower repair shop. Since no other locations were suspected to use TCE,

the number of soil samples collected was reduced from ten to six. Soil samples were 

collected at the following locations: 

1. The Parker County Airport is located near the most northwestern point of the 

documented TCE plume location (Figure 3, SO-04). The Parker County Airport’s 

non-drinking water well had a detection of TCE at 5.4 μg/L (Table 7 and Figure 2, 

GW-04 and duplicate GW-25). Although there is no documented use of TCE at the 

Parker County Airport, its location and lack of many other businesses in the area led 

to its selection as a soil sample location (Ref. 9, pp. 33 and 34; see also Section 2.2.1 

of this HRS documentation record). The slope of the terrain at the airport allowed for 

an excellent soil sample location. A low area created a natural funnel that would 

catch any runoff from coming from the airport’s hangers and control building area. 

2. Ron’s Mower Shop, a seasonally open lawnmower repair shop is located near the 

most northwestern point of the TCE plume, between the Parker County Airport and 

Russell Road (Figure 3, SO-03). Although there is no documented use of TCE at the 

mower repair shop, considering the type of business, its location, and lack of other 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

22

businesses in the area led to its selection as a soil sample location. A non-drinking 

water well is located at Ron’s Mower Shop, which was sampled and no TCE was 

documented in the well (Table 7, and Figure 2, GW-36; Ref. 39, pp. 1-7). The soil 

sample for the lawnmower repair shop was collected close to and directly in front of 

the maintenance building and down slope to catch any releases from that business

(Ref 9, p. 53; Ref 11, p. 21). 

3. No additional potential sources were discovered during the SI; the ESI focused on 

identifying and protecting any population exposed to drinking water wells supplying 

TCE-contaminated water. In addition the comprehensive sampling of wells within an 

1⁄2 mile radius was used to further identify any groundwater concentrations that could 

be indicative of other source areas. The sampling of these wells did not indicate any 

additional potential sources. Within the area of the TCE plume, no soil samples were 

collected during the ESI (Ref. 10, pp. 17,27,29&43; Ref. 11, pp. 4,5,9,10,18&19; Ref. 

13, pp. 11&45; Ref. 14, pp. 3&9).

4. During the ESI sampling event, the well owner of GW-34 expressed concern about an 

active natural gas well located approximately 1,000 feet north of his well (Ref. 13, p. 

9). The filter from well GW-34 appeared black and oily (Ref. 14, p. 2, Photographs 

3&4). TCE was not detected in the GW-34 well (Ref. 25, pp. 12&44). TCE was not 

detected in the closest well to the natural gas well. 
 

 

 

 

 

 

 

 

 

 

!. 

!. 

!. 

!. 

!. 

!. !. 

!. 

!. 

!. 

!.!.SO-03 

SO-01 

SO-02 

SO-04 

SO-05/SO-06 

I 20 

Mikus 

Interstate 20 

Russell 

Rob 

Interstate 20 Service 

WEA 

Oak Hill 

Red Bud 

Parker Oaks 

Mallory 

Southview 

Diamond Oaks 

Arroyo 

Valley 

Circle 

Deer Pond 

Dorris 

Fort Worth 

Big Creek

Oak Hollow

Elm Tree 

Austen 

Live Oak 

Bluebonnet 

Addison 

Park 

Elm 

Green Oaks 

Primrose 

Crown 

Airport 

Pecan Park 

Ranch Oak 

Yucca 

Valley Trail 

Winfield 

McClure

Holly Oak

Brookview 

Oak Hollow 

Fort Worth 

Interstate 20 Service 

Live Oak 

Figure 3: Soil Sample Location Map
 

μ 

Circle Court

Groundwater Plume

Parker County, Texas

TXN000606965
 

Legend 

!. Soil Sample Location 

!. Level 1 Concentration Wells 

Parker County 

This map was generated by the Remediation Division of the Texas

Commission on Environmental Quality. It is intended for illustrative 

or informational purposes only, and is not suitable for legal,

engineering, or survey purposes. This map does not represent an

0 250 500 750 1,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750 3,000 3,250 3,500 3,750 4,000 4,250 4,500 4,750 5,000	 on-the-ground survey conducted by or under the supervision of a

registered professional land surveyor. In cases where property

boundaries are shown, it only represents their approximate relative Feet	 location. No claims are made to the accuracy or completeness of the

data or to its suitability for a particular use. For more information 

concerning this map, contact the Remediation Division at 800-633-9363. The base data set is UTM Zone 14, 0.5 Meter Resolution, Natural Color, NAD 1983 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

24

3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 General Considerations

General Regional Geology

The site is located in the Grand Prairie natural subregion of Texas (Ref. 30, p. 1). The Grand 

Prairie is underlain by alternating limestones and marls of the Cretaceous age Fredericksburg 

Group. The intervening marls form low escarpments that connect successive uplands and 

produce a “cuesta” topography that slopes gently eastward (Ref. 31, p. 11). The 

Fredericksburg Group consists predominantly of limestone, shale, clay, and marl, and yields 

only small amounts of water to localized areas (Ref. 31, p. 15). The City of Willow Park’s 

PWS well located at 117 Circle Court in Willow Park (GW-05 on Figure 2) is located on the 

Walnut Clay Formation, which consists of clay and limestone and has a thickness of 

approximately 30 feet (Ref. 32, p. 6). However, the surface lithology varies considerably 

within small distances due to the interfingering of several different formations, including the 

Goodland Limestone and Walnut Clay of the Fredericksburg Group; the Kiamichi and Duck 

Creek Limestone of the Washita Group; the Quaternary Alluvium; and the Paluxy Formation 

of the Trinity Group (Ref. 34, p. 9). The outcrop of the more permeable sand-dominated and 

water-bearing Paluxy Formation is within 0.10 mile both north and east of the City of Willow 

Park Well #20, and within 0.25 mile of the well in the southwest direction (Ref. 34, p. 9; 

Figure 4A). 

The Fredericksburg Group is underlain by the Cretaceous age Trinity Group formations, 

from youngest to oldest, the Paluxy, Glen Rose, and Twin Mountains. Each of the formations 

is water-bearing and together compose the Trinity aquifer, recognized as a major aquifer by 

the Texas Water Development Board (TWDB) (Ref. 34, p. 9). The TWDB defines a major 

aquifer as one that supplies large quantities of water over large areas of the state (Ref. 44, p. 

4). 

The main source of recharge to the Trinity is precipitation on the outcrops of the formations 

within the aquifer. There are no separations by aquitards or confining layers between the 

formations, and using the Texas Water Development Board’s ground water availability 

model (“GAM”) for the Northern Trinity aquifer, hydrologic interaction was calculated 

between the stratigraphic units. The estimated flow between the Paluxy and the Glen Rose 

was calculated to be 2,678 acre-feet per year, and the Glen Rose into the Upper Travis Peak, 

the equivalent to Twin Mountains in the model, was calculated to be 3,937 acre-feet per year 

(Ref. 34, p. 5, pp. 12-13, p. 22, p. 29). There are no known aquifer discontinuities within the 

four-mile TDL. The nearest zone of faults or fractures is approximately 60 miles east and 

southeast of the site (Figure 4B). The direction of ground water flow in the three formations 

is generally towards the east and southeast (Ref.34, p. 8).

Water use in the area supplied by the Trinity aquifer has increased in the past few
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

25

decades due to increasing population and municipal use. In addition, recent usage has 

increased due to the development of natural gas wells in the Barnett Shale. The water is 

necessary to hydraulically fracture the dense formation around the gas wells, using about 1.2 

to 3.5 million gallons per well during the process. It is estimated that approximately 60 

percent of this water will continue to come from either the Trinity or Woodbine aquifers 

(Ref. 45, p. 9). 

The northern Trinity aquifer is a sole-source water supply for many rural areas and municipal 

supplies (Ref. 35, p. 26). Ground water provided 52.1 percent (11,231 acre-feet of a total 

21,527 acre-feet) of total water used in Parker County in 2006 (Ref.35, p. 33).
Site Center2!!

I - 20

FM 5

FM 730

US HWY 180

FM 1187

FM 51 ST HWY 171

FM 3325

FM 2552

Kpa

Kwa

Kgl

Qal

Kki

Wa

Kdc

Parker

County

This map was generated by the Remediation Division of the Texas

Commission on Environmental Quality. It is intended for illustrative

or informational purposes only, and is not suitable for legal, 

engineering, or survey purposes. This map does not represent an

on-the-ground survey conducted by or under the supervision of a

registered professional land surveyor. In cases where property

boundaries are shown, it only represents their approximate relative

location. No claims are made to the accuracy or completeness of the 

data or to its suitability for a particular use. For more information 

concerning this map, contact the Remediation Division at 800-633-9363.

Figure 4A: Surface Geology Map

Circle Court Groundwater Plume

Parker County, Texas

TXN000606965

The base data used for this map is from the Geologic Database of Texas

published by theTexas Water Development Board and the U.S. Geological Survey. 

The digital data can be accessed at the URL http://data.tnris.org/datadownload/download.jsp

Coordinate system is UTM Zone 15, Northern Hemisphere (NAD 83).

0 0.5 1 2 3 4

Miles

Legend

Paluxy

Walnut Clay

Duck Creek Limestone

Glen Rose Limestone

Kiamichi

Alluvium

μ

Parker County
^_

WOODBINE AQUIFER (subcrop)

NACATOCH AQUIFER (subcrop)

WOODBINE AQUIFER

NACATOCH AQUIFER

CARRIZO AQUIFER

TRINITY AQUIFER

TRINITY AQUIFER (subcrop)

Hill County

Ellis County

Navarro County

Dallas County Parker County Tarrant County

Bosque County

Kaufman County

Johnson County

Wise County Collin County

Hunt County

Denton County

Hood County

Freestone County

Henderson County

Erath County

Somervell County

Jack County

Van Zandt County

Rockwall County

Hamilton County

McLennan County Limestone County

Anderson County

μ

This map was generated by the Remediation Division of the Texas

Commission on Environmental Quality. It is intended for illustrative

or informational purposes only, and is not suitable for legal,

engineering, or survey purposes. This map does not represent an

on-the-ground survey conducted by or under the supervision of a

registered professional land surveyor. In cases where property

boundaries are shown, it only represents their approximate relative

location. No claims are made to the accuracy or completeness of the 

data or to its suitability for a particular use. For more information 

concerning this map, contact the Remediation Division at 800-633-9363.

The base data used for the structural and geologic data for this map is from the Geologic Database of Texas

 published by theTexas Water Development Board and the U.S. Geological Survey. The digital data can be 

accessed at the URL http://data.tnris.org/datadownload/download.jsp. Coordinate system is UTM Zone 15, 

Northern Hemisphere (NAD 83).

Circle Court

Groundwater Plume

Parker County, Texas

TXN000606965

PARKER COUNTY

Legend

Minor Aquifers

Nacatoch (outcrop)

Nacatoch (subcrop)

Woodbine (outcrop)

Woodbine (subcrop)

Structural Features

! ! ! Concealed Normal

Inferred Normal

S Normal

I Overturned Anticline

P Overturned Syncline

F Anticline

+ Thrust

&

Transverse (From-To)

$

Transverse (To-From)

Unspecified

F Syncline

Trinity (outcrop)

Trinity (subcrop)

Major Aquifers

Carrizo (outcrop)

Location Features

^ Approximate

Site Location

4 Mile Radius

Cities

Figure 4B: Regional Geology and Aquifers

0 5 10 20 30 40 50

Miles
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

28

The geologic strata beneath the site, from youngest to oldest, are:

Stratum 1:

The Walnut Clay Formation of the Fredericksburg Group consists of clay and limestone, 

about equally abundant, with a thickness of approximately 30 feet (Ref. 32. p. 6). 

 Walnut Clay Formation - Fredericksburg Group

Stratum 2:

The Paluxy Formation is the uppermost of the three water-bearing formations that comprise 

the Trinity aquifer. The Paluxy is composed predominantly of fine- to coarse-grained, 

friable, homogeneous, white quartz sand, interbedded with sandy, silty, calcareous, or waxy 

clay and shale. The upper Paluxy is fine-grained sand with variable amounts of shale and 

clay. The lower part consists of coarse-grained sand. The sands are usually well-sorted, 

poorly cemented, and crossbedded (Ref. 31, p 19). 

 Paluxy Formation - Trinity Group Aquifer

The Paluxy either underlies one of the Fredericksburg Group formations or outcrops in the 

area of the site (Figure 4A). The primary source of recharge to the Paluxy is precipitation on 

the outcrop. The average annual precipitation on the outcrop is about 31 inches, but only a 

small fraction of the amount is available as effective recharge due to runoff and 

evapotranspiration. Secondary sources include recharge from streams flowing across the 

outcrop, and surface water seepage from lakes. Water in the outcrop area is under water-table 

conditions, and water levels remain fairly constant with only normal seasonal fluctuations. 

In subcrop areas, water is under artesian conditions and is confined under hydrostatic 

pressure from overlying formations. The average rate of movement of water in the Paluxy 

amounts to less than 2 feet per year in an easterly direction except in areas of heavy 

pumpage, where cones of depression have occurred and movement is toward the center of the 

pumped wells. The hydraulic gradient is approximately 27 feet per mile. The direction of 

ground water flow is toward the east and southeast. Discharge from the Paluxy occurs 

naturally through springs and evapotranspiration and artificially through pumpage from water 

wells. The Paluxy is capable of yielding small to moderate amounts of water (Ref. 31, pp. 44, 

46). The City of Willow Park’s PWS well located at 117 Circle Court in Willow Park (GW05 on Figure 2) is screened within the Paluxy Formation of the Trinity aquifer (Ref. 5, p. 56).

Stratum 3

The Glen Rose Formation underlies the Paluxy and consists predominantly of marine 

carbonates, mainly limestone, with some shale, sandy shale, and anhydrite. The formation 

yields small quantities of water to localized areas (Ref. 31, p. 16; Ref. 33, p. 20). 

: Glen Rose Formation - Trinity Group Aquifer

Stratum 4

The Twin Mountains Formation underlies the Glen Rose and consists mainly of medium- to 

coarse-grained sands, red and gray silty clays, and siliceous conglomerates of chert, quartzite, 

and quartz pebbles. The sand strata are more thickly bedded in the lower part of the 

formation than the upper and middle. The majority of wells in this formation are completed 

in the lower massive sand. The direction of ground water flow in the Twin Mountains is 

toward the east and southeast. The Twin Mountains is the most prolific of the Trinity aquifer 

: Twin Mountains Formation - Trinity Group Aquifer
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

29

formations; however, the water quality is generally not as good as that from the Paluxy 

Formation (Ref. 31, p. 18-19; Ref. 33, p. 20).

The Twin Mountains Formation overlies Paleozoic rocks in the study region and is the lower 

member of the Trinity Group. The formation was originally named the Travis Peak 

Formation throughout its extent in Texas, but the north-central portion was subsequently renamed the Twin Mountains Formation because of a lateral facies change (Ref. 31, p. 18; Ref. 

33, p. 20). The Twin Mountains consists mainly of medium- to coarse-grained sands, silty 

clays, and conglomerates, while the Travis Peak contains calcareous sands and silts, 

conglomerates, and limestones (Ref. 33, p. 20). The outcrop of the Twin Mountains covers 

approximately 370 square miles and lies within Hood, Parker and Wise counties. 

Precipitation on the outcrop is the primary source of ground water in the Twin Mountains 

(Ref. 31, p. 41). Only ground water wells screened in the Paluxy formation are considered for 

the purposes of this HRS.

3.1 Likelihood of Release

3.1.1 Observed Release

An observed release was documented to the ground water pathway for the site by chemical 

analysis. To establish an observed release by chemical analysis, it requires analytical 

evidence of a hazardous substance in the media significantly above the background level. If 

the background concentration is not detected, or is less than the detection limit, an observed 

release is established when the sample measurement equals or exceeds the EPA contractrequired quantitation limit (CRQL) when the sample analysis was performed under the EPA 

Contract Laboratory Program (Ref. 1, Section 2.3, Table 2-3).

Background Concentration

Five background samples were collected in excess of a half mile outside of the plume area, 

except for one background well. Background well GW-03 was collected west of the plume 

nearly one half mile away and upgradient and out of the influence of the site. 

The background wells were selected based on the range of their well depths being in the 

same aquifer and of similar depths as the drinking water wells at the site. All of the depths of 

the background wells are known and range from 176’ to 260’ (Ref. 10, pp.3, 21, 23; Ref. 11, 

pp.1,7; Ref. 13, pp. 23, 25; Ref 14 p. 5). Not all of the depths for the domestic water wells 

are specified due to lack of documented information and well owners’ knowledge. There is 

relatively little topographic change in the area of the site and the well depth measurements 

are sufficient to show the depths relative to each other (Ref 3, pp. 1-2). According to a 

Drinking Water Survey Report, the wells with TCE detections and with documented well 

depths had depths similar to the background wells, ranging from 180’ to 280’ (Ref. 28, pp. 7-

8). For the purpose of this record, only those wells installed in the Paluxy formation of the 

Trinity aquifer were included in the Ground Water Migration Pathway Score. Thus, the 

background and release samples are likely from the same aquifer and have the same sample 

similarity. All samples were collected according to the EPA-approved state Quality 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

30

Assurance Project Plan (QAPP) and sample locations were approved by the EPA (Ref. 16; 

Ref. 29, pp. 17-19; Ref. 41, pp. 14-16). Tables 1 and 11 provide well depths, references, and 

TCE detection levels for the wells with observed releases. Table 5 provides well depths and 

references for each of the background ground water samples collected. Table 6 provides a 

summary of the designated background levels for the hazardous substances of concern for 

this site. 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

31

Table 5: Background Ground Water Samples Collected

Sample 

ID*

Sample Location Well Depth 

(feet)

Date 

Collected

References

GW-01 Drinking water well at Highland WSC Well #4; 

3600 Oak Park

250 (Ref. 28, 

p. 8)

3/09/2010 Ref. 10, p. 3; 

Ref. 11, p. 1

GW-31 6/23/2010 Ref. 13, p. 25; 

Ref. 14, p. 5

GW-02 Drinking water well at Hudson Oaks Well #6; 

3250 I-20 East

260 (Ref. 28, 

p. 8)

3/10/2010 Ref. 10, p. 21; 

Ref. 11, p. 7

GW-03 Drinking water well at Hudson Oaks Well #8, 

220 Live Oak

176 (Ref. 28, 

p. 8)

3/10/2010 Ref. 10, p. 23; 

Ref. 11, p. 7

GW-32 Drinking water well at Willow Park PWS –

Willow Springs Well at Quail Crest Road. 

260 (Ref. 13, 

p. 23)

6/23/2010 Ref. 13, p. 23; 

Ref. 14, p. 5

Notes:

* Background sample locations have multiple Sample IDs. The multiple Sample IDs correspond to the same sample location. The multiple 

Sample ID numbers were due to use of different Sample IDs during different sampling events at these sampling locations.

Table 6: Summary of Highest Constituents Detected in the Background Ground Water 

Wells

Sample 

ID

Organic 

Constituent

Highest 

Concentration 

[RL] μg/L*

References

GW-01 Trichloroethene ND [0.5] Ref. 10, p. 3; Ref. 11, p. 1; Ref. 16; Ref. 21, pp. 9,27&36; 

Ref. 29; p. 17; Ref. 38, pp. 1-6

GW-02 Trichloroethene ND [0.5] Ref. 10, p. 21; Ref. 11, p. 7; Ref. 16; Ref. 22, pp. 9,17&20; 

Ref. 29; p. 17; Ref. 38, pp. 1-6

GW-03 Trichloroethene ND [0.5] Ref. 10, p. 23; Ref. 11, p. 7; Ref. 16; Ref. 22, pp. 

10,17&23; Ref. 29; p. 17; Ref. 38, pp. 1-6

GW-31 Trichloroethene ND [0.5] Ref. 13, p. 25; Ref. 14, p. 5; Ref. 16; Ref. 25, pp. 9,32&35; 

Ref. 41; p. 14; Ref. 39, pp. 1-7

GW-32 Trichloroethene ND [0.5] Ref. 13, p. 23; Ref. 14, p. 5; Ref. 16; Ref. 25, pp. 

10,32&38; Ref. 41; p. 14; Ref. 39, pp. 1-7

Notes:

ND = Not Detected

[RL] = Reporting Limit

* For all of the analyses the reporting limit in the references cited is the adjusted for sample volume, dry weight, and dilution factors. The 

RLs are equivalent to adjusted CRQLs and consistent with the HRS defined detection / quantitation limits. (Ref. 36).

Given that all of the background samples have no detected trichloroethene, the background 

level is ND [0.5 μg/L].

Contaminated Samples

The samples in Tables 7 and 8 meet the observed release criteria and are presented below 

indicating the hazardous substance with concentrations and RLs. These samples were 

qualified as “releases” based on the criteria in HRS Table 2-3 (Ref. 1, Section 2.3).
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

32

Table 7: Trichloroethene Contaminated Ground Water Pathway Aquifer Samples 

Meeting Observed Release Criteria 

(March 2010 SI Results)

Sample ID Well Type TCE Conc. 

(μg/L)

RL-

(μg/L)* References

GW-04 &**

Duplicate GW-25

Non-Drinking

Water 5.4 0.5

Ref. 10, p. 37; Ref. 11, pp. 13 – 17; 

Ref. 16; Ref. 22, pp. 14,18,26&35; 

Ref. 29, p. 19; Ref. 38, pp. 1-6

GW-05 PWS Drinking

Water 6.5 0.5

Ref. 10, p. 17; Ref. 11, pp. 4&5; Ref. 

16; Ref. 21, pp. 10,28&39; Ref. 29,

p. 18; Ref. 38, pp. 1-6

GW-10 Private Drinking

Water 10.0 0.5

Ref. 10, p. 27; Ref. 11, p. 9; Ref. 16; 

Ref. 21, pp. 15,31&54; Ref. 29, p. 

19; Ref. 38, pp. 1-6

GW-11 Private Drinking 

Water 2.5 0.5

Ref. 10, p. 29; Ref. 11, p. 10; Ref. 16; 

Ref. 21, pp. 16,32&57; Ref. 29, p. 

19; Ref. 38, pp. 1-6

GW-12 Private Drinking 

Water 1.3 0.5

Ref. 10, p. 43; Ref. 11, pp. 18&19; 

Ref. 16; Ref. 22, pp. 12,19&29; Ref. 

29, p. 19; Ref. 38, pp. 1-6

Notes:

[RL] = Reporting Limit.

* For all of the analyses the reporting limit in the references cited is based on the method detection limit (Ref. 36).

**Sample locations have multiple Sample IDs. The multiple Sample IDs correspond to the same sample location. The multiple Sample ID 

numbers were due to use of different Sample IDs during different sampling events at these sampling locations.

Table 8: Trichloroethene Contaminated Ground Water Pathway Aquifer Samples 

Meeting Observed Release Criteria 

(June 2010 ESI Results)

Sample ID Well Type TCE Conc. 

(μg/L) RL- (μg/L)* References

GW-33 Private Drinking Water 3.8 0.5

Ref. 13, p. 7; Ref. 14, p. 1; 

Ref. 16; Ref. 25, pp. 

11,31&41; Ref. 39, pp. 1-7

GW-41 Private Drinking Water 43.0 0.5

Ref. 13, p. 11; Ref. 14, p. 3; 

Ref. 16; Ref. 25, pp. 

20,31&68; Ref. 39, pp. 1-7

GW-48 Private Drinking Water 2.7 0.5

Ref. 13, p. 45; Ref. 14, p. 9; 

Ref. 16; Ref. 26, pp. 8,12&16; 

Ref. 39, pp. 1-7

Notes:

[RL] = Reporting Limit.

* For all of the analyses the reporting limit in the references cited is based on the method detection limit (Ref. 36).
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

33

Attribution

The site is designated as a contaminated ground water plume originating from unknown 

source(s) where trichloroethene may have been released and percolated through the ground to 

the aquifer. When the source itself consists of a ground water plume with no identified 

source, no separate attribution is required (Ref.1, Sec. 3.1.1). The site is located in a rural 

and residential area, with very little commercial activity. During the SI, conducted in March 

2010, all potential surface sources were sampled (Ref. 10, pp. 47, 49, 51, 53, and 55; Ref. 11, 

pp. 19-21; Ref. 29, pp. 15&23) and no TCE was detected in any of the soil samples (Ref. 9, 

pp. 19-20). The SI was allotted ten soil samples to search for a surface source of TCE 

contamination, due to the lack of commercial activity in the area of the site, only six soil 

samples were collected and no other likely soil sampling locations remained for the ESI. The 

June . No additional potential sources were discovered during the SI; the ESI focused on 

identifying and protecting any population exposed to drinking water wells supplying TCEcontaminated water. In addition the comprehensive sampling of wells within an 1⁄2 mile 

radius was used to further identify any groundwater concentrations that could be indicative of 

other source areas. The sampling of these wells did not indicate any additional potential 

sources. Within area of the TCE plume, no soil samples were collected during the ESI. (Ref. 

10, pp. 17,27,29&43; Ref. 11, pp. 4,5,9,10,18&19; Ref. 13, pp. 11&45; Ref. 14, pp. 3&9). 

The ESI potential source location GW-41 was documented to have the highest level of TCE 

at 43 μg/L (Ref. 13, p. 11; Ref. 14, p. 3; Ref. 16; Ref. 25, pp. 20, 31&68; Ref. 39, pp. 1-7) 

and is also located approximately at the center of the plume, see Figure 2. 

Hazardous Substances Released

The following hazardous substance was released: Trichloroethene

As specified in the HRS (Ref. 1, Section 3.1.1), an observed release factor value of 550 was 

assigned to the Paluxy formation of the Trinity aquifer since an observed release by chemical 

analysis was established in the Paluxy formation of the Trinity aquifer (See Table 11).

Observed Release Factor Value: 550
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

34

3.1.2 Potential to Release

As specified in the HRS, since an observed release was established for the Paluxy formation 

of the Trinity aquifer, the potential to release was not evaluated (Ref. 1, Section 3.1.1).

3.1.3 Likelihood of Release Factor Category Value

As stated in the HRS, if an observed release is established for an aquifer, assign the observed 

release factor value of 550 as the likelihood of release factor category value for the aquifer 

(Ref. 1, Section 3.1.3). Since an observed release has been established for the aquifer, the 

Observed Release Factor Value of 550 is assigned as the likelihood of release factor category 

value.

3.2 Waste Characteristics

3.2.1 Toxicity/Mobility

The hazardous substance with the highest toxicity factor value available to the ground water

migration pathway is trichloroethene, which has a toxicity/mobility value of 1,000. 

Therefore, the following toxicity, mobility, and combined toxicity/mobility factor value has 

been assigned to the substances associated with Source No. 1, or present in the observed 

release, which has a containment value greater than 0.

Table 9: Toxicity/Mobility Factor Values

Hazardous 

Substance

Toxicity 

Factor 

Value

Mobility 

Factor 

Value

Toxicity / 

Mobility

Value

References

Trichloroethene 1,000 1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 2, p. 6

Documentation for Toxicity/Mobility Values

The Mobility Factor Value for all hazardous substances that meet the criteria for an observed 

release by chemical analysis to one or more aquifers underlying the source(s) at the Site, 

regardless of the aquifer being evaluated, is assigned a mobility factor value of 1 (Ref. 1, 

Section 3.2.1.2).

Therefore, the hazardous substance with the highest toxicity/mobility factor value available 

to the ground water migration pathway is trichloroethene with a toxicity/mobility factor value 

of 1,000.

Toxicity/Mobility Factor Value: 1,000
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

35

3.2.2 Hazardous Waste Quantity

The hazardous constituent quantity data is not adequately determined for one or more sources 

for the site. The targets for the Ground Water Migration Pathway are subject to Level I

concentrations (see Tables 7 and 8). According to Section 2.4.2.2 of the HRS, a pathway 

hazardous waste quantity factor value of 100 was assigned because the hazardous constituent 

quantity data is not adequately determined for one or more sources, and targets for the 

Ground Water Migration Pathway are subject to actual contamination (Ref. 1, Section 

2.4.2.2).

Table 10: Source Hazardous Waste Quantity Values

Source Number Source Hazardous Waste Quantity 

Value

Hazardous Constituent Quantity Data 

Complete?

1 > 0 No

Total > 0

3.2.3 Waste Characteristics Factor Category Value

As specified in the HRS (Ref. 1, Section 3.2.3), the Hazardous Waste Quantity Factor Value 

of 100 was multiplied by the highest Toxicity/Mobility Factor Value of 1,000, resulting in a 

product of 100,000 (1.0E+05). Based on this product, a Waste Characteristics Factor Value 

of 18 was assigned from Table 2-7 of the HRS (Ref. 1, Section 2.4.3.1).

Hazardous Waste Quantity Factor Value: 100

Waste Characteristics Factor Value: 18
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

36

3.3 Ground Water Pathway Targets

The primary aquifer being evaluated for the ground water pathway targets is the Paluxy 

formation of the Trinity aquifer. The ground water pathway targets for this aquifer have been 

impacted with trichloroethene above a human health-based cancer risk health-based

benchmark. The number of target wells subject to Level I concentration of trichloroethene, 

which is the concentration above a cancer risk health-based benchmark, is given in Table 11. 

The population served is also given in Table 11. The average population per household of 

3.01, which was based on the Parker County 2010 US Census Bureau information (Ref. 37, 

p. 1), has been applied where the population size was not available from the water well 

survey.

Table 11: Drinking Water Wells with Level I Concentration of Trichloroethene

Well ID

TCE 

Conc. 

μg/L

Benchmarks/Screening 

Concentrations (Ref. 2, p. 6, Ref. 

24, pp. 4-6 & 12)

Well Depth 

(feet)

Population 

Served MCL / Reference

MCLG 

μg/L 

(mg/L)

Cancer 

Risk 

Screen. 

Conc. 

μg/L 

(mg/L)

Ref. 

Dose 

Screen. 

Conc. 

μg/L 

(mg/L)

GW-05 6.5

5.0 μg/L

(5.0E-3)

0.21 μg/L

(2.1E-4)

NA

180 272.48

Ref. 10, p. 17; Ref. 11, pp. 4&5; 

Ref. 16; Ref. 21, pp. 10,28&39; 

Ref. 28, p. 7; Ref. 29; p. 17; Ref. 

38, pp. 1-6; Ref. 40, p. 1

GW-10 10.0 180-200 3.01

Ref. 10, p. 27; Ref. 11, p. 9; Ref. 

16; Ref. 21, pp. 15,31&54; Ref, 

28, p. 7; Ref. 29; p. 18; Ref. 38, 

pp. 1-6; Ref. 37, p. 1

GW11*

GW-33

2.5

100-280 3.01

Ref. 10, p. 29; Ref. 11, p. 10; 

Ref. 13, p. 7; Ref. 14, p. 1; Ref. 

16; Ref. 21, pp. 16,32&57; Ref. 

25, pp. 12,31&41; Ref. 28, p. 7; 

Ref. 29; p. 18; Ref. 38, pp. 1-6; 

Ref. 39, pp. 1-7; Ref. 37, p. 1

3.8

GW-12 1.3

Depth Not 

Specified, 

within 

Paluxy 

Formation

3.01

Ref. 10, p. 43; Ref. 11, pp. 

18&19; Ref. 16; Ref. 22, pp. 

13,19&29; Ref. 29; p. 18; Ref. 

38, pp. 1-6; Ref. 37, p. 1

GW-41 43.0 200 3.01

Ref. 13, p. 11; Ref. 14, p. 3; Ref. 

16; Ref. 25, pp. 21,31&68; Ref. 

28, p. 7; Ref. 39, pp. 1-7; Ref. 

37, p. 1

GW-48 2.7

Depth Not 

Specified, 

within 

Paluxy 

Formation

3.01

Ref. 13, p. 45; Ref. 14, p. 9; Ref. 

16; Ref. 26, pp. 9,12&16; Ref. 

39, pp. 1-7; Ref. 37, p. 1

Total 

Population 

Served

287.53

*GW-11 and GW-33 are samples collected on different dates, from the same well.

 NA= Not available.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

37

3.3.1 Nearest Well

According to Section 3.3.1 of the HRS, if one or more drinking water wells are subject to 

Level I concentrations, a Nearest Well Factor value of 50 is assigned. 

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

Location of Well: Level I concentrations have been documented at six drinking water wells 

within the ground water plume. Well locations are identified in Table 1. The well located at 

405 Russell Road, GW-41, was selected for calculation of the Nearest Well Factor Value, see 

Table 1 and Figure 2. 

The ESI well location GW-41 was documented with 43 μg/L of trichloroethene, which 

exceeds the MCL value of 5 μg/L (Ref. 13, p. 11; Ref. 14, p. 3; Ref. 16; Ref. 25, pp. 20,

31&68; Ref. 39, pp. 1-7). For a well with Level I concentrations, a Nearest Well Factor 

Value of 50 is assigned (Ref. 1, Section 3.3.1). 

Nearest Well Factor Value: 50
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

38

3.3.2 Population

3.3.2.1 Level of Contamination

3.3.2.2 Level I Concentrations

The concentrations of hazardous substance shown in Table 11 include detections in drinking 

water wells that meet or exceed their corresponding benchmark concentrations; thus, these 

wells are associated with Level I concentrations (Ref. 1, Section 3.3.2.1-3.3.2.2).

One public supply and five private wells within a one-mile radius of the Site contained Level 

I concentrations of hazardous substances (see Table 11). All the wells draw water from the 

Paluxy formation of the Trinity aquifer (Ref. 28, pp. 5-8). Public water supply is not 

available to the owners of the private wells subject to Level I concentrations of hazardous 

substances. 

As specified in the HRS (Ref. 1, Section 3.3.2.2), the number of people served by drinking 

water from points of withdrawal subject to Level I concentrations were summed. The City of 

Willow Park has 19 wells serving 1,720 connections. No one well serves more than 40%,

(Ref. 40, p. 1; and Ref. 42, p. 1). Using the average population per household of 3.01 (Ref. 

37, p. 1), the total population counted from Level I wells is 272.48 from GW-05 and 15.05 

from five private drinking water wells for a combined total of 287.53. The total of 287.53

was multiplied by 10, for a product of 2,875.3 (Ref. 1, Section 3.3.2.2).

Calculations of Population Served by Level I wells:

One public supply well (GW-05): 

System serves 1720 (Ref. 40, p. 1) = 1720

Nineteen wells contribute to equally (Ref. 40, p. 1) =

Result = 90.52

÷ 19

Multiplied by the 2010 average population (Ref. 37, p. 1) =

Number of people served by GW-05 Result= 272.48

x3.01

Five Private drinking water wells:

Multiplied by the 2010 average population (Ref. 37, p. 1) = 3.01

Five Wells (GW-10, GW-11, GW-12, GW-41, & GW-48) =

Result = 15.05

x5

Population Served by Level I wells 272.48 + 15.05 = 287.53

Level I Concentration Factor Value 287.53 x 10 (Ref. 1, Section 3.3.2.2) = 2,875.3

Population Served by Level I Well: 287.53 

Level I Concentration Factor Value: 2,875.3
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

39

3.3.2.3 Level II Concentrations

No Level II concentrations of TCE were documented. All concentrations of TCE meeting 

the criteria for an observed release were at Level I Concentrations.

The cancer risk health-based benchmark for TCE cancer risk is 0.21 μg/L (Ref. 2, p. 6, Ref. 

24, pp. 4-6 & 12). Since TCE was not detected in any of the background samples and the

laboratory’s TCE CRQL value of (0.5 μg/L) was greater than TCE’s cancer risk benchmark

(0.21 μg/L), any detections of TCE met both the criteria of an observed release as well as a 

Level I concentration (Ref. 1, Section 2.5.2).

Level II Concentration Factor Value: 0

Population Served by Level II Well: 0
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

40

3.3.2.4 Potential Contamination

The potential contamination factor was evaluated and scored. The ground water wells were 

identified from the well database in the TCEQ GIS servers (Ref. 5). The wells were 

researched within radii of 0 to 0.25, 0.25 to 0.5, 0.5 to1, 1 to 2, 2 to 3, and 3 to 4-miles of the 

site (see Figure 4A of this HRS documentation record). Using the average population per 

household of 3.01 (Ref. 37, p. 1), the potential targets (Table 12) were calculated based on 

the number of wells located within each distance category and the weighted population 

assigned from Table 3-12 of the HRS, using the “Other Than Karst” category. Wells within 

the radii having Level I contamination are not discussed in this section and there are no Level 

II contamination wells, (See Section 3.3.2.3. of this HRS documentation record). Wells 

drawing from aquifers other than the Paluxy formation of the Trinity aquifer are not included 

in this section. PWS systems are included in this potential contamination section, but not 

private domestic drinking water wells, since they lack documentation and add no additional 

value. Texas State well identification numbers, well depths, and distances from the site were

obtained from the Texas Water Development Board’s Water Information Integration and 

Dissemination Groundwater Database interactive viewer, http://wiid.twdb.state.tx.us (Ref. 5). 

Information for the public water system wells were verified through contact with the 

respective water system (Ref. 42; Ref. 43; Ref. 46; Ref. 47).

0 to 0.25-mile

All drinking water wells located in the 0 to 0.25-mile range were sampled and analyzed for 

TCE. Other than the PWS well subject to Level I contamination, no other PWS wells are 

located within this range. 

0.25 to 0.5-mile

In the 0.25 to 0.5-mile range from the site, the following PWS wells are located:

State Well # Depth PWS People Served

3211821 260’ Oak Hill Mobile Home 81.5

3211822 230’ Oak Hill Mobile Home 81.5

3219212 260’ City of Hudson Oaks (Dyegard) 66.97

(Ref. 5, pp.41&57)

Population calculations: The Oak Hill Mobile Home Water Supply’s two wells serve a total 

of 163 people (Ref. 4, p. 26). The City of Hudson Oaks well is a former Dyegard well (Ref. 

43, p. 1). The former Dyegard system includes eight interconnected active drinking water 

wells. No one well contributes more than 40%. The former Dyegard system serves 178 

connections. 178/8 = 22.25 connections per well. 22.25 x 3.01 average household = 66.97 

people served per former Dyegard well. 

The total population served from the 0.25 to 0.5-mile range is 230. Additional wells were 

identified within the 0.25 to 0.5-mile radius; however, insufficient data was available to 

evaluate potential contamination.

 
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

41

0.5 to 1-mile

In the 0.5 to 1-mile range from the site, the following PWS wells are located:

State Well # Depth PWS People Served

3219302 257’ City of Willow Park 272.48

3219303 250’ City of Willow Park 272.48

3219210 253’ City of Hudson Oaks (Dyegard) 66.97

3211803 240’ City of Hudson Oaks 129.96

3211819 200’ City of Hudson Oaks 129.96

3211829 310’ City of Hudson Oaks 129.96

3219204 255’ City of Hudson Oaks 129.96

3219205 196’ City of Hudson Oaks 129.96

3219206 225’ City of Hudson Oaks 129.96

3219207 220’ City of Hudson Oaks 129.96

3219208 220’ City of Hudson Oaks 129.96

3219211 275’ City of Hudson Oaks 129.96

(Ref. 5, pp. 38,40-42&56-58)

Population calculations: 

See city of Willow Park and City of Hudson Oaks Dyegard calculations in 0.25 to 0.5- mile 

radius discussion. The City of Hudson Oaks is separate from the former Dyegard system and 

has 17 active wells supplying water to 734 connections or an average of 43 connections 

serving 129.96 people per well. The 310 foot depth well draws from the Paluxy formation 

(Ref. 43, p. 1).

The total population served from the 0.5 to 1-mile range is 1,782. Additional wells were 

identified within the 0.5 to 1-mile radius; however, insufficient data was available to evaluate 

potential contamination.

1 to 2-mile

In the 1 to 2-mile range from the site, the following PWS wells are located:

State Well # Depth PWS People Served

3211902 183’ City of Willow Park 272.48

3211904 260’ City of Willow Park 272.48

3211905 190’ City of Willow Park 272.48

3211906 260’ City of Willow Park 272.48

3211802 260’ City of Hudson Oaks 129.96

3211827 260’ City of Hudson Oaks 129.96

3211828 230’ City of Hudson Oaks 129.96

3219203 208’ City of Hudson Oaks 129.96

(Ref. 5, pp. 38,41-43&56)
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

42

Population calculations: See 0.5 to 1-mile section population calculations above.

The total population served from the 1 to 2-mile range is 1,610. Additional wells were 

identified within the 1 to 2-mile radius; however, insufficient data was available to evaluate 

potential contamination.

2 to 3-mile

In the 2 to 3-mile range from the site, the following PWS wells are located:

State Well # depth PWS People Served

3211806 143’ City of Willow Park 272.48

3211807 156’ City of Willow Park 272.48

3211809 183’ City of Willow Park 272.48

3211810 179’ City of Willow Park 272.48

3211816 174’ City of Willow Park 272.48

3211817 160’ City of Willow Park 272.48

3211818 153’ City of Willow Park 272.48

3211825 182’ City of Willow Park 272.48

3211907 290’ City of Willow Park 272.48

3219310 306’ City of Willow Park 272.48

(Ref. 5, pp, 38-41&43)

Population calculations: See 0.5 to 1-mile section population calculations above.

The total population served from the 2 to 3-mile range is 2,725. Additional wells were 

identified within the 2 to 3-mile radius; however, insufficient data was available to evaluate 

potential contamination.

3 to 4-mile

No PWS wells drawing from the Paluxy formation of the Trinity aquifer are located within 

the 3 to 4-mile of the site.

As specified in the HRS (Ref. 1, p. 51604), the number of people served by drinking water 

wells was determined within each “Other Than Karst” distance category and a distanceweighted population value for each distance category was assigned. The distance weighted 

population values were summed for a total of 1,597, which was divided by 10 and rounded to 

the nearest integer, for a product of 160 (See Table 12 of this HRS document).
μ

Circle Court 

Groundwater Plume

Parker County, Texas

TXN000606965

!.

!.

!. !.

!.

!.

!.

!.!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!. !.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!. !.

!.

!.

!.!.!.!. !.

!. !.

!.

!.

!.

!.

!.

!. !.

!.

!.

!.

!.

!.

!. !.

!.

!.

!. !.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!. !.

!.

!.

!.

!. !.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.!.

!.

!.

!.

!.

!.

!.

!.

!.!.!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!. !.

!.

!.

!.

!.

!.

!.!.

!.!.!.

!.

!.

!.

!.!.!.

!.

!.

!.!.

!.!.

!. !.

!.!.!.

!.

!.

!.

!. !.

!.

!.

!.

!.

!. !.

!.

!.!.

!. !.

!.

!.!. ! !. .

!.!.

!.!.

!.

!.!.

!.!.

!.

!.

!.

!.

!.

!.

!.!.!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.

!.!.!. !.

!.

!.

!.

!.

!.

!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!. !.

!.

!.

!. !.

!.

!.

!.

!.!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.

!.!.

!. !.!.

!.

!.

9 10 11

This

Co

enter.

Miles

m

or in

engin

on-th

0 1 2 3 4 5 6 7 8

Distance rings placed at 0.25, 0.50, 1.00, 2.00, 3.00 and 4.00-mile intervals from the site c

map was generated by the Remediation Division of the Texas

mission on Environmental Quality. It is intended for illustrative

formational purposes only, and is not suitable for legal, 

eering, or survey purposes. This map does not represent an

e-ground survey conducted by or under the supervision of a

registered professional land surveyor. In cases where property

boundaries are shown, it only represents their approximate relative

location. No claims are made to the accuracy or completeness of the 

data or to its suitability for a particular use. For more information 

concerning this map, contact the Remediation Division at 800-633-9363.

Figure 5: Drinking Water Wells by Distance Radii 

The base data set is UTM Zone 14, 0.5 Meter Resolution, Natural Color, NAD 1983. Texas Water Development Board (TWDB) data and Submitted driller's reports available from 

http://wiid.twdb.state.tx.us. Note: Some wells have geographic coordinants that vary between data sets. For the actual/potential counts in the HRS text, attribute tables were compared 

to ensure each well was only counted once.

Legend

!. Public Water Supply Wells

!. TWDB Groundwater Data

Groundwater Sample Locations

!. Potential Contamination

!. Level 1 Concentration

Parker County

!.

!.

!.

!.!.

!.!.

!.

!.

!.

!.

!.

!.
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

44

Table 12: Potential Contamination

Distance 

(Miles)

Potentially Contaminated

PWS Wells (State Well IDs)

Potentially 

Contaminated

Population

Weighted 

Population Ref.

0 to 0.25 None 0 0

0.25 to 0.5 3 wells (3211821, 3211822, &

3219212) 230 102

Ref. 5, 

pp. 41

& 57

0.5 to 1

15 wells (3219302, 3219303, 

3211804, 3211820, 3211824, 

3219210, 3211803, 3211819, 

3211829, 3219204, 3219205, 

3219206, 3219207, 3219208, & 

3219211)

1,782 523

Ref. 5, 

pp. 38,

40-42 &

56-58

1 to 2

8 wells (3211902, 3211904, 

3211905, 3211906, 3211802, 

3211827, 3211828, & 3219203)

1,610 294

Ref. 5, 

pp. 38,

41-43 &

56

2 to 3

10 wells (3211806, 3211807, 

3211809, 3211810, 3211816, 

3211817, 3211818, 3211825, 

3211907, & 3219310)

2,725 212

Ref. 5, 

pp, 38-

41 & 43

3 to 4 None 0 0

Total 6,347 1,131

3.3.3 Resources

No resources, as defined in HRS Section 3.3.3, were documented for the Paluxy formation of 

the Trinity aquifer (Ref. 1). 

3.3.4 Wellhead Protection Area

The Wellhead Protection Area (WPA) has not been evaluated at this time.

Potential Contamination Factor Value: 113

Resource Factor Value: 0

Wellhead Protection Area Factor Value: NE
Hazard Ranking System Documentation Record Circle Court Ground Water Plume

March 2012 TXN 000 606 965

45

3.3.5 Calculation of Targets Factor Category Value

The target factor category value is calculated by determining the sum of the factor values for 

the nearest well (50), population (2,988.3), resources (0), and WPA (0) (Ref. 1, Section 

3.3.5).

Calculations: 50 + 2,988.3 + 0 + 0 = 3,038.3

3.4 Ground Water Migration Score for an Aquifer

The ground water migration score for an aquifer is calculated by multiplying the factor 

category values for likelihood of release (550), waste characteristics (18), and targets 

(3,038.3). Divided by 82,500, the resulting value (maximum value 100) is assigned as the 

ground water migration pathway score (Ref. 1, Section 3.4).

Calculations: (550 x 18 x 3,038.3) / 82,500 = 364.596 (100 maximum)

3.5 Calculation of Ground Water Migration Pathway Score

The ground water migration pathway score is calculated by assigning the highest ground

water migration score for the aquifer being evaluated (100).

3.5.1 Calculation of HRS Site Score

The HRS site score is calculated by using the root-mean-square equation which squares each 

pathway score then takes the sum of all pathways and divides the sum by 4 then takes the 

square root which is the site score (Ref. 1, Section 2.1.1).

Calculations:

GW Pathway [100] = 10,000

Pathway Squares

SW Pathway not scored = 0

Soil Pathway not scored = 0

Air Pathway not scored = 0

Sgw + Ssw + Ss + Sa = 10,000 + 0 + 0 + 0 = 10,000

10,000 / 4 = 2,500

√ 2,500 = 50.00

HRS Site Score: 50.00