HAZARD RANKING SYSTEM (HRS)

DOCUMENTATION RECORD - REVIEW COVER SHEET

Name of Site: Eldorado Chemical Co., Inc. 

EPA ID No.: TXD057567216 

Contact Persons 

Site Investigation: Brenda Nixon Cook, NPL Coordinator, EPA Reg.6 (214) 665-7436 

 (Name) (Telephone) 

Documentation Record: Brenda Nixon Cook, NPL Coordinator, EPA Reg.6 (214) 665-7436 

 (Name) (Telephone) 

Pathways, Components, or Threats Not Scored 

1) Soil Exposure Pathway: The soil exposure pathway has not been scored because although there 

is sampling to show a release has occurred, there are not a sufficient number of targets to 

impact the site score. Furthermore, although there are indications of contaminated soil present 

that could threaten targets, it has not been scored as an evaluation of the soil exposure pathway 

would not affect the listing decision (Ref. 1, Section 2.2.3). The soil evaluation pathway will be 

further investigated if it becomes a concern in the future. 

2) Air Pathway: Based on information available at this time, evaluation of the air migration 

pathway would not affect the listing decision (Ref. 1, Section 2.2.3). The air migration 

pathway will be further investigated if it becomes a concern in the future. 

3) Surface Water Pathway: Based on information available at this time, evaluation of the surface 

water migration pathway would not affect the listing decision (Ref. 1, Section 2.2.3). The 

surface water pathway will be further investigated if it becomes a concern in the future. 

HRS Documentation Record Eldorado Chemical Co., Inc.

TXD057567216
HRS DOCUMENTATION RECORD

Name of Site: Eldorado Chemical Co., Inc. 

Site Spill Identifier No.: A6AS

EPA Site ID No.: TXD057567216 

EPA Region: 6 

Date Prepared: April 2016 

Street Address of Site*: 14350 Lookout Road 

City, County, and State: Live Oak, Bexar County, Texas 78233* 

General Location within the State: 

The Eldorado Chemical Co., Inc., site is located at 14350 Lookout Road 

in Live Oak, Bexar County, Texas, within south-central Texas (See HRS 

documentation record Figure 1a for Regional Location Map, Figure 1b 

for Site Topographic Map, and Figure 1c for Site Location and 

Surrounding Land Use Map).

Topographic Map(s): The following U.S. Geological Survey (USGS) 7.5-minute series 

topographic map was used in locating the facility: Schertz Quadrangle, 

Texas (1992) (Ref. 2, p. 1). 

Latitude/Longitude*: 29° 34’ 7.80” N, 98° 21’ 0.15” W

Latitude and Longitude coordinates were measured from the location of MW-07 and were determined 

using a scaled topographic map and Geographic Information System (GIS) software (Ref. 2, p. 1; Ref. 

37, pp. 1, 2). 

 

 Scores 

 Air Pathway Not Scored

 Ground Water Pathway 77.70

 Soil Exposure Pathway Not Scored

 Surface Water Pathway Not Scored

 HRS SITE SCORE 38.85

*The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area the site 

is located. They represent one or more locations EPA considers to be part of the site based on the screening information EPA used to 

evaluate the site for NPL listing. EPA lists national priorities among the known "releases or threatened releases" of hazardous 

substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has 

been "deposited, stored, disposed, or placed, or has otherwise come to be located." Generally, HRS scoring and the subsequent listing of 

a release merely represent the initial determination that a certain area may need to be addressed under 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.

HRS Documentation Record 1 Eldorado Chemical Co., Inc.

TXD057567216
NOTES TO THE READER

1. The following rules were applied when citing references in this documentation record: 

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 has a two-digit number followed by the sequential number (e.g., Reference 4, 

Page 1 is expressed as 4.001 in Reference 4). 

2. Hazardous substances are often listed by the names used in the Superfund Chemical Data 

Matrix (SCDM) (Ref. 3). 

3. 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 Texas House Bill 

2912, Article 18 of the 77th Regular Legislative Session. 

HRS Documentation Record 2 Eldorado Chemical Co., Inc.

TXD057567216
SYNONYMS

1,1-Dichloroethylene = 1,1-Dichloroethene 

cis-1,2-Dichloroethylene = cis-1,2-Dichloroethene 

trans-1,2-Dichloroethylene = trans-1,2-Dichloroethene 

Tetrachloroethylene = Tetrachloroethene

Trichloroethylene = Trichloroethene 

HRS Documentation Record 3 Eldorado Chemical Co., Inc.

TXD057567216
REFERENCES CITED

1. United States Environmental Protection Agency (EPA). 1990. Hazard Ranking System

(HRS); Final Rule. 14 December 1990. Volume 55, No. 241 (Excerpts). Page: 1. [A complete

copy of the HRS can be obtained at the Regional docket upon request or is also available at

http://semspub.epa.gov/src/document/HQ/174028].

2. U.S. Geological Survey (USGS). 1992. 7.5-Minute Topographic Series Maps: Schertz, Texas

Quadrangle. 1 page.

3. EPA. 2015. Superfund Chemical Data Matrix (SCDM) (Excerpts). December 2015. 62

pages. [A complete copy of SCDM is available at http://www.epa.gov/superfund/superfundchemical-data-matrix-scdm]. Accessed January 25, 2016 and February 23, 2016.

4. Texas Commission on Environmental Quality. Industrial and Hazardous Waste Notice of

Registration Report. Retrieved February 2, 2009. 23 pages.

5. Johnson, Heather D., P.G. Re: Environmental Document Review, Eldorado Chemical

Company. Raba-Kistner Consultants, Inc. April 13, 2009. 28 pages.

6. Rickhoff, Gerry, Bexar County Clerk. Industrial Solid Waste Disposal Site Deed Recordation –

Eldorado Chemical Company, Inc. May 14, 1999. 16 pages.

7. Wareing & Associates, Inc. Initial Phase-II Subsurface Investigation Conducted on El Dorado

Chemical Company, 14350 Lookout Road, Live Oak, Bexar County, Texas (Excerpts). July 25,

2001. 8 pages.

8. Murray, Gene, P.G. Environmental Site Assessment Summary Report – 14350 Lookout Road,

Live Oak, Texas. W&M Environmental Group, Inc. February 24, 2006. 10 pages.

9. Texas Commission on Environmental Quality. Photographic Documentation from the Eldorado

Chemical Co. Region 13 Investigation on December 19, 2007. 14 pages.

10. Texas Commission on Environmental Quality. Photographic Documentation and Field Notes

from the Eldorado Chemical Co. Pre-CERCLIS Screening Investigation on March 6, 2009. 28

pages.

11. U.S. Environmental Protection Agency Region 6 Laboratory. Final Analytical Report – El

Dorado Chemical Co 04/04/11-04/06/11. May 17, 2011. 365 pages.

12. Cave, Michael. Photographic Documentation Log from the Eldorado Chemical Co. Site

Inspection dated April 4-6 and April 13, 2011. 31 pages.

13. Texas Commission on Environmental Quality. Field Notes from the Eldorado Chemical Co.

Site Inspection Preparation and Site Inspection on March 31, 2011 and April 4-6, 2011. 20

pages.

HRS Documentation Record 4 Eldorado Chemical Co., Inc.

TXD057567216
14. Arredondo, R., Geostrata Inc. Groundwater Monitoring Field Data, Eldorado Chemical 4/4/11-

4/5/11. April 4-5, 2011. 6 pages. 

15. Arnow, Ted. Ground-water Geology of Bexar County, Texas. Texas Board of Water Engineers. 

Bulletin 5911 (Excerpts). October, 1959. 49 pages.

16. Texas Water Development Board (TWDB). Geologic Atlas of Texas, San Antonio Sheet. 

Revised 1982. Accessed at http://www.twdb.texas.gov/groundwater/aquifer/GAT/sanantonio.htm on August 24, 2012. 3 pages. 

17. San Antonio Water System. News: Billions of Gallons Coming to San Antonio Via SchertzSeguin. Accessed at http://www.saws.org/latest_news/NewsDrill.cfm?news_id=999 on 

February 23, 2016. 2 pages. 

18. Clark, Amy R., Charles D. Blome, and Jason R. Faith. Map Showing Geology and 

Hydrostratigraphy of the Edwards Aquifer Catchment Area, Northern Bexar County, SouthCentral Texas. U. S. Geological Survey Open-File Report 2009-1008. 2009. Pages 4, 5, and 8 

modified with site location text by M. Brown with Weston Solutions, Inc. 24 pages. 

19. Stein, William G. and Ozuna, George B. Geologic Framework and Hydrogeologic 

Characteristics of the Edwards Aquifer Recharge Zone, Bexar County, Texas: U.S. Geological 

Survey Water-Resources Investigations 95-4030. 1995. 13 pages.

20. Barker, Rene A. and Ardis, Ann F. Hydrogeologic Framework of the Edwards-Trinity Aquifer 

System, West-Central Texas. U. S. Geological Survey Professional Paper 1421-B. 1996. 76 

pages.

21. University of Maryland Department of Environmental Safety, Sustainability and Risk. EPA 

Hazardous Waste Codes. Accessed at: http://www.des.umd.edu/hw/rest/manual/codes.html on 

18 March 2016. 15 pages. 

22. Reference Number Reserved

23. Lingren, R. J., A. R. Dutton, S. D. Hovorka, S. R. H. Worthington, and S. Painter. 

Conceptualization and Simulation of the Edwards Aquifer, San Antonio Region, Texas. U. S. 

Geological Survey Scientific Investigations Report 2004-5277. 2004. Page 14 modified with 

site location text by M. Brown with Weston Solutions, Inc. 154 pages. 

24. Texas Commission on Environmental Quality. Texas Drinking Water Watch. Release 3.1. 

Public Water Supply System Summary Pages. Accessed at http://dww2.tceq.texas.gov/DWW/

on January 26, 2016. 121 pages. 

25. Texas Commission on Environmental Quality. Telephone Memo to the File: Call from Mike 

Cave, TCEQ Project Manager, to Jim Neeley, Utility Supervisor at Live Oak Public Works. 

June 8, 2012. 1 page. 

HRS Documentation Record 5 Eldorado Chemical Co., Inc.

TXD057567216
26. Texas Commission on Environmental Quality. Telephone Memo to the File: Call from Mike

Cave, TCEQ Project Manager, to Blake Partridge, Superintendent [sic] to the Water

Department of Universal City Public Works. June 4, 2012. 1 page.

27. Weston Solutions, Inc. (WESTON). Email correspondence between Michelle Brown

WESTON Project Manager, and Larry Verner, P.E., City Engineer for the City of Selma.

January 28, 2016. 1 page.

28. Texas Commission on Environmental Quality. Email correspondence between Mike Cave,

TCEQ Project Manager, and Tracy Campos, Office Manager for the Utilities Department of the

City of Converse. May 4-9, 2012. 2 pages.

29. Texas Commission on Environmental Quality. Email correspondence between Mike Cave,

TCEQ Project Manager, and Monty McGuffin, Groundwater resource Protection Supervisor

for the San Antonio Water System. June 12-June 21, 2012. 3 pages.

30. Texas Commission on Environmental Quality. Telephone Memo to the File: Call from Mike

Cave, TCEQ Project Manager, to Richard Frenzel, General Manager of the Bexar County

Water Control and Improvement District 10 Windcrest Water System. June 5, 2012. 1 page.

31. Reference Number Reserved

32. Pedraza, Diana E. and Sachin D. Shah. Geodatabase Design and Characteristics of Geologic

Information for a Geodatabase of Selected Wells Penetrating the Austin Group in Central

Bexar County, Texas, 2010. U.S. Geological Survey Data Series 522. 2010. 48 pages.

33. Maclay, Robert W. Geology and Hydrogeology of the Edwards Aquifer in the San Antonio

Area, Texas. U.S. Geological Survey Water-Resources Investigations Report 95-4186. 1995.

72 pages.

34. San Antonio Water System. Source Water/Wellhead Protection Program. Accessed at:

http://www.saws.org/environment/ResourceProtComp/groundwater_protection/source_water_p

rogram/sourcewater_program.pdf on September 6, 2012. 13 pages.

35. Zara Environmental, LLC. Final Report for Deep Aquifer Biota Study of the Edwards Aquifer.

December 30, 2010. 109 pages.

36. Edwards Aquifer Research and Data Center. Endangered Species – Threatened and Endangered

Species in the Edwards Aquifer System. Accessed at

http://www.eardc.txstate.edu/about/endangered.html on September 14, 2012. 4 pages.

37. WESTON. Project Note to File. Subject: Eldorado Chemical Co., Inc. Task Description:

Calculating Latitude and Longitude Coordinates of the Site. W.O. No.

20406.012.019.0968.01. February 22, 2016. Pages: 2.

38. Texas Water Development Board (TWDB) Ground Water Data – Driller’s Logs from twentyone (21) wells located within 2.0 miles of Eldorado Chemical facility. Accessed at

HRS Documentation Record 6 Eldorado Chemical Co., Inc.

TXD057567216
http://www2.twdb.texas.gov/apps/WaterDataInteractive/GroundWaterDataViewer on 

November 4, 2015. 153 pages.

39. Texas Water Development Board (TWDB) - Report 296, Carbonate Geology and Hydrology of 

the Edwards Aquifer in the San Antonio Area, Texas (Excerpts). November 1986. 63 pages. 

40. Texas Commission on Environmental Quality. Expanded Site Inspection Report. Eldorado 

Chemical Co., Inc. June 2014. 405 pages. 

41. Geo Strata Environmental. Field Notes from Passive Soil Gas Survey at Eldorado Chemical 

Co., Inc. July, August, and September 2013. 5 pages. 

42. Texas Commission on Environmental Quality. Photograph Log from the Expanded Site 

Inspection Passive Soil Gas Sampling Event at Eldorado Chemical Co., Inc. August 26, 2013 

August 27, 2013, and September 11, 2013. 44 pages. 

43. Beacon Environmental Services, Inc. Passive Soil Gas Survey – Analytical Report Beacon 

Project No. 2718 El Dorado Chemical Company, Live Oak, TX. October 24, 2013. 26 pages. 

44. Texas Commission on Environmental Quality. Site Inspection Report for Eldorado Chemical 

Co., Inc. Volume 1 of 2 (Excerpts). August 2011. 44 pages. 

45. WESTON. Project Note to File. Subject: Eldorado Chemical Co., Inc. Task Description: 

Sample Quantitation Limit (SQL) Calculation. W.O. NO. 20406.012.019.0963.01. January 19, 

2016. Pages: 1.

46. WESTON. Project Note to File. Subject: Eldorado Chemical Co., Inc. Task Description: 

Calculating the Area of Source 1. W.O. NO. 20406.012.019.0963.01. February 9, 2016. Pages: 

2. 

47. EPA. Toxics Release Inventory Factsheet. TRI Explorer. 2013 TRI Factsheet. Accessed at 

http://www.epa.gov/toxics-release-inventory-tri-program on February 9, 2016. TRI search 

conducted for zip code 78233. 2014 Dataset released October 2015. Pages: 2. 

48. EPA. 2015. EnviroMapper for Envirofacts database. 

http://www.epa.gov/emefdata/em4ef.home. Site accessed and spreadsheet and data

downloaded February 9, 2016. Page 2 modified with site and property location text by M. 

Brown with Weston Solutions, Inc. Pages: 9. 

HRS Documentation Record 7 Eldorado Chemical Co., Inc.

TXD057567216
SITE SUMMARY

The site includes the location of the release of hazardous substances from the Eldorado Chemical Co., 

Inc., (Eldorado) facility and the potential migration of that release to the Edwards Aquifer system. The 

Eldorado facility operated as a cleaning products manufacturer at the property from at least 1978 to 2007. 

Documented historical releases of hazardous substances known to be used at the Eldorado facility have 

contributed to contaminated soil found in the south and southeastern portion of the facility property and 

extending east of the property boundary. Additionally, an unknown volume of contaminated ground water 

has been documented beneath and adjacent to the facility property. Environmental samples collected

during other previous investigations, including the April 2011 Site Inspection, indicate the presence of 

volatile organic compounds (VOCs) in soil and shallow ground water at the property. The contaminated 

soil and other contamination at the property are the identified sources in this HRS documentation record 

and the boundary of their associated contamination is the site (Figure 2 of this HRS documentation 

record). 

Eldorado was registered with the TCEQ as a Large Quantity Generator by the TCEQ Industrial and 

Hazardous Waste (IHW) Section from 1978 to 2007 (Ref. 4, p. 2). According to the IHW Notice of 

Registration, the facility managed hazardous materials and generated an extensive list of waste streams, 

consisting of both acute hazardous wastes and toxicity characteristic wastes. Included in this list are the 

following waste streams:

• sodium cyanide and cadmium plating solutions (Ref. 4, p. 17); 

• reactive wastes including sodium cyanide and zinc fluorosilicate (Ref. 4, p. 16); 

• organic and inorganic sludges and wastewater containing tetrachloroethylene (PCE) (waste 

number D039), trichloroethylene (TCE) (waste number D040), cresol (waste number D026), 

methyl ethyl ketone (waste number D035), o-dichlorobenzene (waste number U070), formic 

acid (waste number U123), and phenol (waste number U188) (Ref. 4, p. 11; Ref. 21, pp. 1, 10, 

11,13); 

• halogenated solvent mixtures (Ref. 4, pp. 5, 12, 13); 

• spent degreasers (Ref. 4, p. 5); and 

• lab packs containing off-specification chemicals (Ref. 4, p. 10). 

As a result of compliance inspections in the 1980s, three areas of concern at the site were identified by the 

Texas Water Commission (TWC), a predecessor agency to the TCEQ: the area immediately adjacent to 

the Powder Room and wastewater tanks, an area near a maintenance shop, and the southeastern corner of 

the property in the vicinity of the product storage area (Ref. 5, p. 5). The property owner, PIF Partnership, 

conducted remediation activities between 1984 and 1986, including the removal of soil and visibly 

impacted areas at each of the areas of concern (Ref. 5, p. 5). The first two areas were closed in accordance 

with the current state regulatory program at the time (Risk Reduction Standard) (Ref. 5, p. 6). An Agreed 

Final Judgment was issued by the TWC in February 1986 which required completion of remedial 

activities (Ref. 5, p. 6). It is not known if, or to what extent, these activities were completed; however, the 

Agreed Final Judgment was closed in October 1994, when approximately 1.54 acres of the property were 

deed recorded due to residual contaminant concentrations remaining in the soil (Ref. 5, p. 6). The deed 

recordation includes the analytical results of samples collected from the property at unknown locations in 

January 1985 by Raba-Kistner Consultants, Inc. (Ref. 6, pp. 2, 5, 6). Soil samples analyzed for VOCs 

contained concentrations of acetone, ethylbenzene, PCE, toluene, and TCE (Ref. 6, p. 5). A subsurface 

soil sample and a ground water sample both contained concentrations of phenol (Ref. 6, p. 6). 

HRS Documentation Record 8 Eldorado Chemical Co., Inc.

TXD057567216
As a result of hazardous waste handling violations noted during two 1993 compliance inspections, a new 

Agreed Order was issued in 1996 requiring the violations to be addressed (Ref. 5, p. 6). Eldorado had 

failed to document that hazardous waste determinations had been conducted on several waste streams, 

hazardous waste was being stored on-site without TNRCC authorization, and they had failed to notify 

TNRCC that the facility was operating as a transfer facility for hazardous waste (Ref. 5, p. 6). Subsequent 

inspections in 1999 and 2001 noted further administrative violations, in addition to three areas of 

unauthorized discharges of chemicals near the above-ground storage tanks (AST) tertiary containment 

drain valve, an area used for storage of empty chemical bags, and the discharge point from the loading 

dock located in the southeastern portion of the property (Ref. 5, pp. 6-7). 

From July 23 to 25, 2001, Wareing and Associates (Wareing), a consultant for Eldorado Chemical Co., 

Inc., conducted an Initial Phase II Subsurface Investigation at the facility as part of the due diligence 

process (Ref. 5, p. 7; Ref. 7, pp. 1-8). Soil boring and ground water samples were collected from at least 

19 locations, including an adjacent water supply well to the south and a monitoring well at the southeast 

corner of the property (Ref. 5, pp. 8-9; Ref. 7, pp. 2-8). Analyses of these samples indicated subsurface 

soil and ground water had been impacted by VOCs and semi-volatile organic compounds (SVOCs) (Ref. 

5, p. 9; Ref. 7, pp. 2-8). Subsurface samples collected from depths of 6 to 24 feet below ground surface 

(bgs) detected concentrations of 1,1-dichloroethane (1,1-DCA), 1,1-dichloroethylene (1,1-DCE), 1,2,4-

trichlorobenzene, 1,2-dichloroethane (1,2-DCA), 1,4-dichlorobenzene, chlorobenzene, naphthalene, PCE, 

and TCE, (Ref. 7, pp. 2-3, 5-8). The sample from the monitoring well contained concentrations of 1,1-

DCA, 1,2-dichlorobenzene, 1,4-dichlorobenzene, chlorobenzene, cis-1,2-dichloroethylene, and methylene 

chloride (Ref. 7, pp. 2-4).

In 2005, Wareing installed one additional soil boring adjacent and east of the Powder Room (Ref. 5, p. 9). 

VOCs were detected in a soil sample and ground water sample collected from the borehole (Ref. 5, p. 9). 

The exact location of the soil boring is unknown, as full documentation for this event could not be 

obtained. 

In February 2006, W&M Environmental Group (W&M) conducted further assessment activities at the 

facility on behalf of Eldorado, including the installation of at least three temporary wells in locations 

across the property and five soil borings in the vicinity of the Powder Room (Ref. 5, p. 9; Ref. 8, pp. 1, 4). 

VOCs, including PCE, 1,1-DCE, 1,2-DCA, and vinyl chloride, were detected in three of the temporary 

wells (Ref. 8, p. 4). The compounds 1,2,4-trichlorobenzene, and 1,4-dichlorobenzene were detected in the 

soil borings collected near the Powder Room (Ref. 5, p. 10; Ref. 8, pp. 2-3, 5). Comparing their data with 

the 2001 and 2005 Wareing data, W&M concluded that VOC concentrations in the southeastern corner of 

the property suggested a past release from the septic system (Ref. 5, p. 10; Ref. 8, pp. 1-11). 

In November 2006, W&M collected additional soil samples near the tertiary containment valve and from 

the former location of a storage trailer utilized to store empty chemical bags (Ref. 5, pp. 10, 28). SVOCs 

and total petroleum hydrocarbons (TPH) were detected at some of the boring locations, and RCRA 8 

Metals (arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver) were detected in each 

of the soil borings (Ref. 5, p. 10). 

A TCEQ Region 13 investigator returned to the facility on December 19, 2007 and took photographs (Ref. 

9, pp. 1-14). Paint stains and chemical corrosion were documented in the laboratories, restrooms, Powder 

Room, outdoor product storage area, and other rooms in the facility (Ref. 9, pp. pp. 2-9). The tertiary 

containment system valve cap was found unlocked and open (Ref. 9, p. 10). One metal tank in the product 

HRS Documentation Record 9 Eldorado Chemical Co., Inc.

TXD057567216
storage area contained an unknown liquid (Ref. 9, p. 12). The hatches on three empty tanks that formerly 

stored hazardous waste in the product storage area had been unbolted and removed (Ref. 9, p. 11). 

A Pre-CERCLIS site inspection was conducted by TCEQ Remediation Division and Region 13 personnel 

on March 6, 2009 (Ref. 10, pp. 1-28). Chemical dye and paint staining was further documented in several 

of the facility bathrooms and laboratories (Ref. 10, pp. 1-2, 6, 24). Significant staining, corrosion, and 

erosion of the concrete floor were observed in the Kiln Room, the Pratt and Whitney Room, and the 

Powder Room (Ref. 10, pp. 3-5, 11, 24, 26). Distressed vegetation was observed downhill from the facility

in the surface drainage pathway (Ref. 10, pp. 21-22, 28).

The target aquifer (aquifer of concern) is the Edwards Aquifer system. The Edwards Aquifer system is 

the sole source of water for the San Antonio area, where it provides domestic, public supply, industrial, 

and agricultural water (Ref. 20, pp. 54, 55). There are 29 public water supply (PWS) wells located within 

the 4-mile target distance limit (TDL) of the site that are being scored in this HRS evaluation, serving 

approximately 215,722 people in total (Ref. 24 pp. 1-121; Table 16 and Figure 3b of this HRS 

documentation record). The karst and fractured limestone conditions associated with the geologic 

formations of the Edwards Aquifer system establish effective porosity that provides efficient pathways for 

contamination to enter the aquifer and migrate through fractures (Ref. 19, pp. 5-7). In addition, over 40 

species of vertebrates and invertebrates, including eight endangered and threatened species, inhabit the 

aquifer (Ref. 18, p. 5; Ref. 35, p.7, Ref. 36, pp. 1-4).

HRS Documentation Record 10 Eldorado Chemical Co., Inc.

TXD057567216
WORKSHEET FOR COMPUTING HRS SITE SCORE

 S S2

1. Ground Water Migration Pathway Score (Sgw) 77.70 6,037.29 

(from Table 3-1, line 13) 

2a. Surface Water Overland/Flood Migration Component NS NS

(from Table 4-1, line 30) 

2b. Ground Water to Surface Water Migration Component NS NS

(from Table 4-25, line 28) 

2c. Surface Water Migration Pathway Score (Ssw) NS NS

(Enter the larger of lines 2a and 2b as the pathway score)

3. Soil Exposure Pathway Score (Ss) NS NS

(from Table 5-1, line 22) 

4. Air Migration Pathway Score (Sa) NS NS 

(from Table 6-1, line 12) 

 

5. Total of Sgw

2 + Ssw2 + Ss2 + Sa2

 6,037.29 

 HRS Site Score: Divide the value on line 5 by 4 and take 

 the square root. 38.85

Notes: 

S Score

S2 Score squared

NS Not scored

Table 3-1, refers to score sheets presented in the HRS (Ref. 1). Table 3-1 is reproduced on the following page of this HRS 

documentation record for the convenience of the reader.

HRS Documentation Record 11 Eldorado Chemical Co., Inc.

TXD057567216
HRS 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 0

2. Potential to Release:

 2a. Containment 10 10

 2b. Net Precipitation 10 1

 2c. Depth to Aquifer 5 1

 2d. Travel Time 35 1

 2e. Potential to Release [lines 2a x (2b + 2c + 2d)] 500 30

3. Likelihood of Release (higher of lines 1 and 2e) 550 30

Waste Characteristics:

4. Toxicity/Mobility (a) 10,000

5. Hazardous Waste Quantity (a) 10

6. Waste Characteristics 100 18

Targets:

7. Nearest Well 50 20

8. Population:

 8a. Level I Concentrations (b) 0

 8b. Level II Concentrations (b) 0

 8c. Potential Contamination (b) 11,846

 8d. Population (lines 8a + 8b + 8c) (b) 11,846

9. Resources 5 0

10. Wellhead Protection Area 20 5

11. Targets (lines 7 + 8d + 9 + 10) (b) 11,871

Ground Water Migration Score For An Aquifer:

12. Aquifer Score [(lines 3 x 6 x 11) ÷ 82,500] (c) 100 77.70

Ground Water Migration Pathway Score:

13. Pathway Score (Sgw), 

(highest value from line 12 for all aquifers evaluated)c 100 77.70

(a) Maximum value applies to waste characteristics category.

(b) Maximum value not applicable.

(c) Do not round to nearest integer.

HRS Documentation Record 12 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

SOURCE 1: SOURCE DESCRIPTION

2.2 Source Characterization: Source 1 – Contaminated Soil

2.2.1 Source Identification

Source Description: Source 1 – Contaminated Soil

Source Type: Contaminated Soil

Source 1 is the contaminated soil discovered during initial assessment activities conducted in 2001 as 

part of the due diligence process (Ref. 5, pp. 7, 9-10; Ref. 8, pp. 1, 5). Eldorado Chemical Company, 

Inc. operated as a cleaning products manufacturer from 1978 to 2007 (Ref. 44, p. 11). Additionally, 

the facility managed hazardous materials and generated waste streams containing halogenated solvent 

mixtures, such as PCE, used to wash parts (Ref. 4, pp. 12, 13). During this assessment, four borings 

were installed near septic tank leach fields and the soil samples collected were found to contain 

volatile compounds utilized at the facility (Ref. 5, p. 9). 

Additional assessment activities conducted in the vicinity of a septic tank were conducted in 2005 and 

2006 (Ref. 5, pp. 9-11). The closer to the septic system the soil was sampled, the higher the 

concentration of 1,2,4-Trichlorobenzene. 1,2,4-Trichlorobenzene, and daughter product 1,4-

dichlorobenzene likely represent a historical release in the septic system (Ref. 8, p. 3). 

Location of Source 

Source 1 is located on the southeastern portion of the property and also extends southeast of the 

facility boundary (See Figure 2 of this HRS documentation record) (Ref. 8, p. 1).

Source Containment

A release of hazardous substances on the property is documented due to the detections of VOCs and 

SVOCs contamination within vadose zone soils (Ref. 5, p. 9; Ref. 7, pp. 2-8). No liner was present and 

native soil contained contamination. Surface and subsurface soil samples were collected from 

boreholes at Source 1, as well as soil gas samples (Ref. 7, pp. 2-8; Ref. 12, pp. 13-16; Ref. 13, pp. 7, 8; 

Ref. 41, pp. 1-5; Ref. 42, pp. 1-44; Ref. 43, pp. 21-22). Evidence of migration from the contaminated 

soil to the ground water is shown through the sampling conducted during the Site Inspection sampling 

conducted by TCEQ Remediation Division personnel at the Eldorado property in April 2011, as 

discussed in the Source 2 section of this HRS documentation record. The highest concentrations of 

benzene, chlorobenzene, naphthalene, toluene, vinyl chloride, and cyanide were found in well GW-04, 

located in the southeastern portion of the property adjacent to the former product storage area and 

septic tank (Ref. 44, pp. 20, 32-37). 

A containment value of 10 was selected for Source 1 – Contaminated Soil based on the evidence of 

hazardous substance migration to the vadose zone soils and the absence of a liner (Ref. 1, Table 3-2).

Containment Value: 10 

HRS Documentation Record 13 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

2.4.1 Hazardous Substances

From July 23 to 25, 2001, Wareing and Associates (Wareing), a consultant for Eldorado Chemical Co., 

Inc., conducted an Initial Phase II Subsurface Investigation at the facility as part of the due diligence 

process (Ref. 5, p. 7; Ref. 7, pp. 1-8). Soil boring samples were collected, and analyses of these 

samples indicated subsurface soil had been impacted by VOCs and SVOCs (Ref. 5, p. 9; Ref. 7, pp. 2-

8). Subsurface samples collected from depths of 6 to 24 feet below ground surface (bgs) detected 

concentrations of 1,1-dichloroethane (1,1-DCA), 1,1-dichloroethylene (1,1-DCE), 1,2,4-

trichlorobenzene, 1,2-dichloroethane (1,2-DCA), 1,4-dichlorobenzene, chlorobenzene, naphthalene, 

PCE, and TCE (Ref. 7, pp. 2-3, 5-8). This is data that was reported by the facility and the laboratory 

data package associated with the samples was not available. However, as the 2001 Phase II 

Subsurface Investigation was conducted on behalf of the Eldorado Chemical Co., Inc., the data are

considered accurate and valid (Ref. 7, p.1). 

To establish relative concentrations for surrounding soils, a sample point collected for background 

purposes during the April 2011 Site Inspection was used for comparison purposes. Additionally, most 

chlorinated solvents are manmade substances that do not occur naturally within the environment. 

Therefore, the below detection background levels for these types of substances can be considered 

representative of background conditions in the area. Sample location SO-12/SO-13 is located 

approximately 250 feet northeast of the property (Ref. 44, pp. 19, 20; Figure 2 of this HRS 

documentation record). The soil samples were analyzed using method OLM04.2-GC/MS (low level) 

and collected on April 5, 2011 (Ref. 11, pp. 145, 166; Ref. 44, p. 22). A pick and spoon were used to 

break up and remove soils from the 0-6 inch depth interval before a dedicated spoon was used to 

collect the sample from the 6-12 inch depth interval. The sample collected from the 0-6 inches depth 

interval were collected using methods identified in the approved work plan (Ref. 44, pp. 14, 15). 

Summarized below are the background sample results. 

Table 1 – Background Soil 

2011 Site Inspection

Hazardous

Substance

Evidence

References

Client Sample 

ID/Depth of 

Sample

RL*

(mg/kg)

Concentration

(mg/kg)

1,1-Dichloroethane SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 145, 357; Ref. 13, p. 7

1,1-Dichloroethylene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 145, 357; Ref. 13, p. 7

1,2-Dichloroethane SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 145, 357; Ref. 13, p. 7

1,4-Dichlorobenzene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 146, 357; Ref. 13, p. 7

1,2,4-Trichlorobenzene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 146, 357; Ref. 13, p. 7

Chlorobenzene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 146, 357; Ref. 13, p. 7

cis-1,2-Dichloroethylene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 145, 357; Ref. 13, p. 7

Tetrachloroethylene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 146, 357; Ref. 13, p. 7

Trichloroethylene SO-12 (0-6”) 0.0065 0.0065 U Ref. 11, pp. 145, 357; Ref. 13, p. 7

1,1-Dichloroethane SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 166, 358; Ref. 13, p. 7

1,1-Dichloroethylene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 166, 358; Ref. 13, p. 7

1,2-Dichloroethane SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 166, 358; Ref. 13, p. 7

HRS Documentation Record 14 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

Hazardous

Substance

Evidence

References

Client Sample 

ID/Depth of 

Sample

RL*

(mg/kg)

Concentration

(mg/kg)

1,4-Dichlorobenzene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 167, 358; Ref. 13, p. 7

1,2,4-Trichlorobenzene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 167, 358; Ref. 13, p. 7

Chlorobenzene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 167, 358; Ref. 13, p. 7

cis-1,2-Dichloroethylene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 166, 358; Ref. 13, p. 7

Tetrachloroethylene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 167, 358; Ref. 13, p. 7

Trichloroethylene SO-13 (6-12”) 0.0059 0.0059 U Ref. 11, pp. 166, 358; Ref. 13, p. 7

Note:

mg/kg – milligrams per kilogram

1 milligram = 1,000 micrograms

U – Undetected (Ref. 11, p. 365)

RL – Reporting Limit (Ref. 11, p. 6) 

* - The Reporting Limit is equal to the Sample Quantitation Limit (SQL) and is adjusted for sample volume and 

dilutions as defined in the HRS (Ref. 1, Section 1.1; Ref. 11, p. 6; Ref. 45). 

Summarized in the following table is analytical evidence of contamination found during the 2001 

sampling associated with Source 1. Sample locations are shown in Figure 2 of this HRS 

documentation record. 

Table 2 – Contaminated Soil 

Source Hazardous Substances

2001 Phase II Subsurface Investigation 

Hazardous

Substance

Evidence

References

Sample 

Location/

Approximate 

Depth

Concentration

(mg/kg)

1,2,4-Trichlorobenzene B-13 (12’) 0.0191 Ref. 7, p. 6

1,4-Dichlorobenzene B-13 (12’) 2.75 Ref. 7, p. 6 

Chlorobenzene B-13 (12’) 0.0323 Ref. 7, p. 6

cis-1,2-Dichloroethylene B-13 (12’) 0.0916 Ref. 7, p. 6

1,4-Dichlorobenzene B-13 (23’) 0.451 Ref. 7, p. 6

1,2,4-Trichlorobenzene B-14 (14’) 4.39 Ref. 7, p. 6

1,2-Dichloroethane B-14 (14’) 0.0423 Ref. 7, p. 6

1,4-Dichlorobenzene B-14 (14’) 0.0125 Ref. 7, p. 6 

cis-1,2-Dichloroethylene B-14 (14’) 0.155 Ref. 7, p. 6

Tetrachloroethylene B-14 (14’) 0.0858 Ref. 7, p. 6

Trichloroethylene B-14 (14’) 0.36 Ref. 7, p. 6 

1,4-Dichlorobenzene B-15 (6.5’) 0.00961 Ref. 7, pp. 3, 6

Chlorobenzene B-15 (6.5’) 0.0616 Ref. 7, pp. 3, 6

cis-1,2-Dichloroethylene B-6 (7’) 0.0611 Ref. 7, pp. 3, 7

Trichloroethylene B-6 (7’) 0.135 Ref. 7, pp. 3, 7

1,2-Dichloroethane B-7 (16’) 0.0269 Ref. 7, pp. 3, 7

HRS Documentation Record 15 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

Hazardous

Substance

Evidence

References

Sample 

Location/

Approximate 

Depth

Concentration

(mg/kg)

1,4-Dichlorobenzene B-7 (16’) 0.136 Ref. 7, pp. 3, 7

Chlorobenzene B-7 (16’) 0.0155 Ref. 7, pp. 3, 7

Tetrachloroethylene B-7 (16’) 0.13 Ref. 7, pp. 3, 7

1,4-Dichlorobenzene B-7 (22’) 0.0719 Ref. 7, pp. 3, 7

Chlorobenzene B-7 (22’) 0.00687 Ref. 7, pp. 3, 7

Tetrachloroethylene B-7 (22’) 0.0554 Ref. 7, pp. 3, 7

1,1-Dichloroethane B-8 (11’) 0.0067 Ref. 7, pp. 3, 7

1,4-Dichlorobenzene B-8 (11’) 0.395 Ref. 7, pp. 3, 7

Chlorobenzene B-8 (11’) 0.158 Ref. 7, pp. 3, 7

1,4-Dichlorobenzene B-8 (21’) 0.0627 Ref. 7, pp. 3, 7

Chlorobenzene B-8 (21’) 0.126 Ref. 7, pp. 3, 7

cis-1,2-Dichloroethylene B-8 (21’) 0.0579 Ref. 7, pp. 3, 7

1,1-Dichloroethylene B-10 (23’) 0.128 Ref. 7, pp. 3, 7

1,4-Dichlorobenzene B-1 (8’) 0.513 Ref. 7, pp. 3, 8

Tetrachloroethylene B-1 (8’) 0.00675 Ref. 7, pp. 3, 8

1,4-Dichlorobenzene B-2 (9’) 0.014 Ref. 7, pp. 3, 8

Chlorobenzene B-2 (9’) 0.0235 Ref. 7, pp. 3, 8

 Note:

mg/kg – milligrams per kilogram

Although the soil samples above were collected in 2001, the soil gas samples presented below 

represent more recent data that was collected in 2013. Samples PSG-03, PSG-04, and PSG-05 were 

collected in the vicinity of sample locations B-1, B-6 and B-8 shown above and verify the continuing 

presence of the contamination at the site (Figure 2 of this HRS documentation record; Ref. 7, pp. 2, 3; 

Ref. 43, p. 17). 

On August 26 and 27, 2013, TCEQ personnel and contracted staff installed Beacon passive soil gas

samplers at 20 locations in three different areas near the Eldorado property (Ref. 40, p. 29; Ref. 41, pp. 

2-3; Ref. 42, pp. 1-21). The work was completed according to the August 2013 Work Plan and Quality 

Assurance Project Plan (QAPP) (Ref. 40, pp. 31-48). Five samplers were installed near the southeast 

corner of the facility near the location of the septic tank (Ref. 7, p. 3; Ref. 40, p. 48). These locations 

were selected because these wells contained the highest concentrations of VOCs in the August 2011 

Site Inspection. Five more samplers were installed in the wooded vacant property east of the property, 

approximately halfway between the property and the Bridlewood neighborhood to the southeast (Ref. 

40, p. 14; Ref. 42, pp. 17-21), and nine samplers were installed along the drainage ditch that runs 

southeast to northwest along the border of the Bridlewood neighborhood (Ref. 42, pp. 8-16). The 

samplers remained in the soil until September 11, 2013, when they were retrieved, placed in sample 

shipping bags, and shipped to the analytical testing laboratory (Ref. 41, p. 4-5; Ref. 42, pp. 22-44). The 

samples were submitted to Beacon Environmental Services, Inc. (Beacon) in Forest Hill, Maryland and 

analyzed for VOCs, SVOCs, and total petroleum hydrocarbons (TPH) following EPA Method 8260C 

(Ref. 43, p. 1). 

HRS Documentation Record 16 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

To establish relative background concentrations for surrounding soils, a sample point collected for 

background purposes during the August 2013 Passive Soil Gas Survey was used for comparison 

purposes. Additionally, PCE is a manmade chlorinated solvent that does not occur naturally within the 

environment. The background levels for PCE of less than the reporting limit can be considered 

representative of conditions in the area. Sample location PSG-16 is located approximately 450 feet 

northeast of the Eldorado property (Figure 2 of this HRS documentation record; Ref. 43, p. 11). The 

soil gas samples were thermally desorbed analyzed using method using EPA method 8260C and 

collected on September 11, 2013 (Ref. 43, pp. 3, 5-10). The samples were collected using field 

procedures for passive soil-gas surveys during the same sampling event by the same sampling 

personnel (Ref. 43, pp. 18-22).

Summarized below are the background sample results. 

Table 3 – Background Soil Gas

August 2013 Passive Soil Gas Survey 

Hazardous

Substance

Evidence

References Client Sample 

ID

RL*

(ng)

Concentration

(mg/kg)

Tetrachloroethylene PSG-16 10 < 10 Ref. 43, pp. 1, 9, 22, 25

Naphthalene PSG-16 25 < 25 Ref. 43, pp. 1, 9, 22, 25

Chloroform PSG-16 25 < 25 Ref. 43, pp. 1, 9, 22, 25

ng – nanogram

< - less than

RL – Reporting Limit. The baseline above which results exceed laboratory-determined limits of precision and 

accuracy (Ref. 43, p. 1)

* The Reporting Limit is a quantitation limit and is adjusted for sample volume and dilutions as defined in the 

HRS (Ref. 1, Section 1.1; Ref. 43, p. 1; Ref. 45).

Summarized in the following table is analytical evidence of contamination found during the 2013 

passive soil gas sampling associated with Source 1. 

HRS Documentation Record 17 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

Table 4 – Contaminated Soil 

Source Hazardous Substances

August 2013 Passive Soil Gas Survey 

Hazardous

Substance

Evidence

References Client Sample 

ID

RL*

(ng) 

Concentration

(mg/kg)

Tetrachloroethylene PSG-03 10 8 J Ref. 43, pp. 1, 6, 21, 25

Naphthalene PSG-04 25 85 Ref. 43, pp. 1, 7, 21, 25

Tetrachloroethylene PSG-05 10 10 Ref. 43, pp. 1, 7, 21, 25

Chloroform PSG-10 25 109 Ref. 43, pp. 1, 8, 21, 25

Tetrachloroethylene PSG-18 10 6 J Ref. 43, pp. 1, 9, 22, 25

Note:

ng – nanogram

RL – Reporting Limit. The baseline above which results exceed laboratory-determined limits of precision and 

accuracy (Ref. 43, p. 1) 

* The Reporting Limit is a quantitation limit and is adjusted for sample volume and dilutions as defined in the 

HRS (Ref. 1, Section 1.1; Ref. 43, p. 1; Ref. 45).

J – Values below limit of quantitation, but above limit of detection (Ref. 43, pp. 1, 6-10). There is no bias 

associated with the J qualifier (Ref. 43, p. 1). The presence of this substance is also not in doubt. 

 

 

HRS Documentation Record 18 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

2.4.2 Hazardous Waste Quantity

2.4.2.1 Source Hazardous Waste Quantity

2.4.2.1.1 Tier A: Hazardous Constituent Quantity – Not Estimated (NE)

 

The total Hazardous Constituent Quantity for Source No. 1 could not be adequately determined 

according to the HRS requirements; that is, the total mass of all Comprehensive Environmental 

Response, Compensation and Liability Act (CERCLA) hazardous substances in the source and 

releases from the source is not known and cannot be estimated with reasonable confidence [Ref. 1, pp. 

51590-51591 (Section 2.4.2.1.1)]. Insufficient historical and current data [manifests, potentially 

responsible party (PRP) records, State records, permits, waste concentration data, etc.] are available to

adequately calculate the total mass, or a partial estimate, of all CERCLA hazardous substances in the 

source and the associated releases from the source. Therefore, there is insufficient information to 

calculate a total or partial Hazardous Constituent Quantity estimate for Source No. 1 with reasonable 

confidence. 

2.4.2.1.2 Tier B: Hazardous Wastestream Quantity – Not Estimated (NE)

The total Hazardous Wastestream Quantity for Source No. 1 could not be adequately determined 

according to the HRS requirements; that is, the total mass, or a partial estimate, of all hazardous 

wastestreams and CERCLA pollutants and contaminants for the source and releases from the source is 

not known and cannot be estimated with reasonable confidence [Ref. 1, p. 51591 (Section 2.4.2.1.2)]. 

Insufficient historical and current data (manifests, PRP records, State records, permits, waste 

concentration data, annual reports, etc.) are available to adequately calculate the total mass, or a partial 

estimate, of all hazardous wastestreams and CERCLA pollutants and contaminants for the source and 

the associated releases from the source. Therefore, there is insufficient information to adequately 

calculate or extrapolate a total or partial Hazardous Wastestream Quantity for Source No. 1 with

reasonable confidence.

2.4.2.1.3 Tier C: Volume

The volume of the contaminated soil cannot be adequately determined based on the information 

available. The depth of contaminated soil throughout the area is not known. Thus, the volume will be 

assigned a value of 0 for Source 1 [(Ref. 1, p. 51591 (Section 2.4.2.1.3)]. 

 Volume Assigned Value = 0

2.4.2.1.4 Tier D: Area

The area of Source 1 was determined by measurements obtained by using Geographic Information 

System (GIS) software (Ref. 46). The area of Source 1 was calculated to total 201,616 square feet 

(ft2) (Figure 2 of this HRS documentation record; Ref. 46, pp. 1, 2). The Tier D equation for assigning 

a value for area source type “Contaminated Soil” is A/34,000 [(Ref. 1, p. 51591 (Table 2-5, Section 

2.4.2.1.4)]. Calculations for Source 1 are as follows: 

Area of Source 1 (square feet): 201,616 

HRS Documentation Record 19 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 1

Area Assigned Value = 201,616/34,000 

Area Assigned Value = 5.929 

2.4.2.1.5 Source Hazardous Waste Quantity Value

Per the HRS, the highest of the values assigned to the source for hazardous constituent quantity (Tier 

A), hazardous wastestream quantity (Tier B), volume (Tier C), and area (Tier D) should be assigned as 

the source hazardous waste quantity value [(Ref. 1, p. 51591 (Section 2.4.2.1.5)]. 

Table 5 

Source 1 – Contaminated Soil

Source Hazardous Waste Quantity 

Tier Evaluated Source 1 Values

A Not Estimated

B Not Estimated

C 0

D 5.929

Source Hazardous Waste Quantity Value: 5.929 

HRS Documentation Record 20 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 2

SOURCE 2: SOURCE DESCRIPTION

2.2 Source Characterization: Source 2 – Unallocated Source

2.2.1 Source Identification

Source Description: Source 2 – Unallocated Source

If a hazardous substance known to be associated with the site cannot be documented as associated with 

an identified source, the HRS directs that it can be considered to be present in each site source, unless 

definitive information indicates that the hazardous substance was not or could not be present in that 

source (Ref. 1, Section 2.2.2). The HRS also directs that these hazardous substances be considered a 

separate “unallocated” source for purposes of evaluating the Hazardous Waste Quantity Factor Value 

(Ref. 1, Section 2.4.2). 

Source Type: Other

Source 2 is an unknown area of contamination that is documented to be present at the site as 

demonstrated by the presence of contaminated ground water located under the Eldorado Chemical Co., 

Inc., property (Figure 2 of this HRS documentation record, see Tables 6 and 7 below; Ref. 44, pp. 16-

17). The contaminated ground water (see Table 7 below) resulted from facility operations due to the 

lack of off property contamination sources, as shown in section 3.1.1 of this HRS documentation 

record, and historic use of halogenated solvent mixtures at the Eldorado Chemical Co., Inc. facility, 

since the ground water also contains some of the same substances (see section 2.4.1 of this HRS 

documentation record below) found in their listed historical waste streams: sodium cyanide (Ref. 4, p. 

17); reactive wastes including sodium cyanide (Ref. 4, pp. 16, 17); organic sludges containing PCE, 

TCE, and dichlorobenzene (Ref. 4, p. 13; Ref. 21, pp. 1, 10); halogenated solvent mixtures (Ref. 4, pp. 

5, 12, 13); and spent degreasers (Ref. 4, p. 5). In addition, these contaminants are not ubiquitous 

throughout the environment (see sections 2.4.1 (Source 1) and 3.1.1 of this HRS documentation 

record). 

Location of Source 

Source 2 is located under or adjacent to the Eldorado Chemical Co., Inc. property and to the southeast 

of the property boundary (Figure 2 of this HRS documentation record; Ref. 44, pp. 16-17). 

Source Containment

The Containment Factor Value for the ground water migration pathway was evaluated for “All 

Sources” for evidence of hazardous substance migration from the 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 monitoring wells as shown in Section 2.4.1 below (Figure 2 and Table 7 of this HRS 

documentation record). 

A containment value of 10 was selected for Source 2 – Other (unallocated source) based on the 

evidence of hazardous substance migration meeting observed release criteria to the shallow ground 

HRS Documentation Record 21 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 2

water as presented below and in Section 3.1.1 of this HRS documentation record (Ref. 1, Table 3-2).

Containment Value: 10 

2.4.1 Hazardous Substances

A site inspection was conducted by TCEQ Remediation Division personnel at the Eldorado facility on 

April 4-6, 2011. Ground water samples were collected from eight on- and off-property monitoring 

wells. VOCs and SVOCs, including benzene, chlorobenzene, PCE, TCE, toluene, and vinyl chloride, 

as well as cyanide, were detected in one or more monitoring wells above their respective maximum 

contaminant level (MCL) for drinking water. The highest concentrations of benzene, chlorobenzene, 

naphthalene, toluene, and vinyl chloride, were found in well GW-04, located in the southeastern 

portion of the Eldorado property adjacent to the former product storage area and septic tank (Ref. 44, 

pp. 20, 32-37). 

To establish relative background concentrations for the ground water samples, a sample point collected 

for background purposes during the April 2011 Site Inspection sampling event was used for 

comparison purposes. Sample location GW-10 is located at the San Antonio Water System Naco 

Station PWS Pump #4 (Ref. 44, pp. 17, 21). Additionally, most chlorinated solvents are manmade 

substances that do not occur naturally within the environment. Therefore, the below detection

background levels for these types of substances can be considered representative of background 

conditions in the area. Ground water samples from monitoring wells were collected using a 

submersible bladder pump and low-stress (low flow), minimal drawdown collection procedures as 

described in the work plan. The submersible pump was decontaminated at the beginning of the 

sampling event and between each sample (Ref. 44, p. 15). Ground water samples from public and 

private water supply wells were collected directly from sampling ports as described in the work plan 

(Ref. 12, p. 30; Ref. 13, pp. 3-6, 7-11; Ref. 44, p. 15). All samples were prepared and preserved using 

the methods and equipment described in the work plan and QAPP for the 2011 site inspection (Ref. 44, 

p. 15). The ground water samples were analyzed using method OLM04.2-GC/MS (low level) and 

collected on April 4, 5, and 6, 2011 (Ref. 11, pp. 24, 38, 52, 59, 75, 82, 103, 110, 224; Ref. 44, p. 22). 

Summarized below are the background sample results.

Table 6 – Background Ground Water

April 2011 Site Inspection Sampling

Hazardous

Substance

Evidence

References Client Sample 

ID 

RL*

(ug/L)

Concentration

(ug/L)

trans-1,2-Dichloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Benzene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Toluene GW-10 0.5 0.5 U Ref. 11, pp. 225, 361

Vinyl Chloride GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Cyanide GW-10 10 19.8 Ref. 11, pp. 228, 361

Notes: 

ug/L – microgram per liter

U – Undetected (Ref. 11, p. 365)

RL – Reporting Limit adjusted for sample size and matrix interference (Ref. 11, p. 6)

HRS Documentation Record 22 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 2

* RL is equal to the sample quantitation limit (SQL) and is adjusted for sample volume and dilutions as defined in 

the HRS (Ref. 1, Section 1.1; Ref. 11, p. 8; Ref. 45).

Summarized in the following table is analytical evidence of contamination found during the 2011 Site 

Inspection sampling associated with Source 2. 

For all hazardous substances but cyanide, the background level is 0.5 ug/L. The background level 

established for cyanide is 19.8 ug/L and the level to show a significant increase is 59.4 ug/L. Ground 

water samples identified below are those that are significantly above background as defined by the 

HRS (Ref. 1, Section 2.3, Table 2-3) and attributable to the site (see section 3.1.1 of this HRS 

documentation record). 

Table 7 

Hazardous Substances Associated With Source 2

Ground Water 

April 2011 Site Inspection Sampling

Evidence

Hazardous

Substance

Client Sample 

ID 

RL*

(ug/L) 

Concentration

(ug/L) References

trans-1,2-Dichloroethylene GW-03 0.5 1.6 Ref. 11, pp. 24-25, 349

Benzene GW-04 25 194 Ref. 11, pp. 38-39, 350

Toluene GW-04 25 268 Ref. 11, pp. 38-39, 350

trans-1,2-Dichloroethylene GW-04 25 114 Ref. 11, pp. 38-39, 350

Vinyl Chloride GW-04 25 3820 Ref. 11, pp. 38-39, 350

Cyanide GW-05 10 455 Ref. 11, pp. 79, 353

Benzene GW-07 2.5 13.8 Ref. 11, pp. 59-60, 351

Vinyl Chloride GW-07 2.5 27.2 Ref. 11, pp. 59-60, 351

Note:

ug/L – microgram per liter

RL – Reporting Limit adjusted for sample size and matrix interference (Ref. 11, p. 6) 

* RL is equal to the sample quantitation limit (SQL) and is adjusted for sample volume and dilutions as defined in 

the HRS (Ref. 1, Section 1.1; Ref. 11, p. 8; Ref. 45).

These hazardous substances, although documented as being present at the site, cannot be attributed to a 

specific source, but their release can be attributed to the site (see section 3.1.1 of this HRS 

documentation record). Therefore, these hazardous substances are considered to be present in each 

source at the site (Ref. 1, Section 2.2.2). 

2.4.2 Hazardous Waste Quantity

2.4.2.1 Source Hazardous Waste Quantity

2.4.2.1.1 Tier A: Hazardous Constituent Quantity - Not Estimated (NE)

The total Hazardous Constituent Quantity for Source 2 could not be adequately determined according 

to the HRS requirements; that is, the total mass of all CERCLA hazardous substances in the source and 

HRS Documentation Record 23 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 2

releases from the source is not known and cannot be estimated with reasonable confidence [Ref. 1, pp. 

51590-51591 (Section 2.4.2.1.1)]. Insufficient historical and current data [manifests, PRP records, 

State records, permits, waste concentration data, etc.] are available to adequately calculate the total 

mass, or a partial estimate, of all CERCLA hazardous substances in the source and the associated 

releases from the source. Therefore, there is insufficient information to calculate a total or partial 

Hazardous Constituent Quantity estimate for Source 2 with reasonable confidence. 

2.4.2.1.2 Tier B: Hazardous Wastestream Quantity 

The total Hazardous Wastestream Quantity for Source 2 could not be adequately determined according 

to the HRS requirements; that is, the total mass, or a partial estimate, of all hazardous wastestreams 

and CERCLA pollutants and contaminants for the source and releases from the source is not known 

and cannot be estimated with reasonable confidence [Ref. 1, p. 51591 (Section 2.4.2.1.2)]. Insufficient 

historical and current data (manifests, PRP records, State records, permits, waste concentration data, 

annual reports, etc.) are available to adequately calculate the total mass, or a partial estimate, of all 

hazardous wastestreams and CERCLA pollutants and contaminants for the source and the associated 

releases from the source. Based on the presence of contaminated samples though, the value of Tier B 

will be assigned a value of greater than (>) 0, but exact quantity unknown, for Source 2 [Ref. 1, p. 

51591 (Section 2.4.2.1.2)]. 

Hazardous Wastestream Quantity Assigned Value: >0, but unknown 

2.4.2.1.3 Tier C: Volume

Because a hazardous wastestream quantity of greater than 0, but exact quantity unknown, was assigned 

to Source 2, 0 is the volume assigned value for Tier C [Ref. 1, p. 51591 (Section 2.4.2.1.3)].

 Volume Assigned Value = 0 

2.4.2.1.4 Tier D: Area

Because a volume of greater than 0, but exact quantity unknown, was assigned to Source 2, 0 is the 

area assigned value for Tier D [Ref. 1, p. 51591 (Section 2.4.2.1.4)]. 

Area Assigned Value = 0

2.4.2.1.5 Source Hazardous Waste Quantity Value

Per the HRS, the highest of the values assigned to the source for hazardous constituent quantity (Tier 

A), hazardous wastestream quantity (Tier B), volume (Tier C), and area (Tier D) should be assigned as 

the source hazardous waste quantity value [(Ref. 1, p. 51591 (Section 2.4.2.1.5)]. 

 

HRS Documentation Record 24 Eldorado Chemical Co., Inc.

TXD057567216
Source Characterization - Source 2

Table 8 

Source 2 – Unallocated Source

Source Hazardous Waste Quantity 

Tier Evaluated Source 2 Values 

A Not Estimated

B >0, but exact quantity unknown

C 0

D 0

Source Hazardous Waste Quantity Value: >0, but exact quantity unknown 

HRS Documentation Record 25 Eldorado Chemical Co., Inc.

TXD057567216
Likelihood of Release

3.0 GROUND WATER MIGRATION PATHWAY SCORE 

3.0.1 General Considerations

The Edwards Aquifer system (frequently referred to in literature as the Edwards Aquifer) contains at 

least two individual karst aquifers, in the Kainer and Person Formations of the Edwards Group, and is 

one of the most productive carbonate aquifer systems in the nation. This dissolution-modified, faulted 

limestone aquifer system is the sole source of public-water supply for San Antonio and is the major 

source of water for Bexar County (Ref. 19, p. 5). The Kainer and Person Formations are considered 

one hydrological unit (Ref. 19, pp. 11, 12). See Table 9 for the typical stratigraphic correlations of the 

Edwards Aquifer system in the region (Ref. 19, p. 8). Overlying the Edwards Aquifer system are 

several stratigraphic units, such as the Austin Group (also referred to as the Austin Chalk) and 

Quaternary Alluvium that yield ground water (Ref. 15, Table 1, p. 16), and are a source of ground 

water recharge to the Edwards Aquifer system (Ref. 19, pp. 5, 10; Ref. 39, p. 22). 

The Person Formation is divided into three geologic members: undivided cyclic and marine members; 

undivided leached and collapsed members, an aquifer; and the regional dense member. The undivided 

leached and collapsed members range from 70 to 90 feet thick and are composed of crystalline 

limestone to grainstone, chert, and collapsed breccias (Ref. 19, p. 8). Extensive lateral cavern 

development and large rooms are associated with this member (Ref. 19, p. 8). 

The Kainer Formation is divided into four geologic members: the grainstone member, an aquifer; the 

Kirschberg evaporite member, an aquifer; the dolomitic member, an aquifer; and the basal nodular 

member (Ref. 19, p. 8). The Kirschberg evaporite member is one of the most permeable with likely 

extensive cavern development (Ref. 19, p. 8). The Kirschberg evaporite member appears to be the 

most porous and permeable subdivision with boxwork void configuration and secondary neospar and 

travertine deposits (Ref. 19, p. 11). The dolomitic member is composed of mudstone to grainstone; 

crystalline limestone; and chert, and thickness ranges from 110 to 130 feet (Ref. 19, p. 8). Some beds 

in this member are relatively permeable and porous as a result of burrowing and dissolution causing a 

honeycombed framework (Ref. 19, p. 11). The basal nodular member is composed of shaly, nodular 

limestone, mudstone, and miliolid grainstone and is 50 to 60 feet thick (Ref. 19, p. 8). This member is 

one of the more extensively karstified with large lateral caves developed in the outcrop surface, 

allowing for secondary porosity (Ref. 19, p. 11). 

The Edwards Aquifer system has relatively large permeability, in part, from the development or 

redistribution of secondary porosity. Lithology, stratigraphy, diagenesis, and selective dissolution 

(karstification) account for the effective porosity and permeability (Ref. 19, p. 10). The karst and 

fractured limestone conditions associated with the geologic formations establish effective porosity that 

provide efficient pathways for contamination to enter the aquifer and migrate through fractures, etc. 

(Ref. 15, p. 19; Ref. 19, pp. 5, 7; Ref. 38, pp. 15, 18, 23, 55, 63, 64, 65, 67, 74, 75, 91, 92, 101, 102, 

114, 115, 134, 146, 147). 

The Person and Kainer Formations are considered one hydrologic unit consistent with the historic 

regional approach (Ref. 15, pp. 22, 27; Ref. 19, p. 9; Ref. 39, p. 23). Water well reports and drilling 

logs within the investigation area identify karst features and/or fractured limestone conditions along 

with faulting which promotes hydraulic communication within the Edwards Aquifer system (Ref. 15, 

HRS Documentation Record 26 Eldorado Chemical Co., Inc.

TXD057567216
Likelihood of Release

p. 19; Ref. 19, pp. 5, 7; Ref. 38, pp. 15, 18, 23, 55, 63, 64, 65, 67, 74, 75, 91, 92, 101, 102, 114, 115, 

134, 146, 147). 

Regional Geology 

Table 9

Hydrogeologic Strata 

Hydrogeologic 

Units

Group, Formation, Member Thickness

(feet) Porosity/Permeability Type

Upper Cretaceous

Upper Units

Pecan Gap Chalk 350-500 Southern Bexar Co. has some 

bearing strata

water 

Austin Group 200-350 Minor aquifer that is interconnected 

with the Edwards Aquifer 

Upper Confining Units

Eagle Ford Group 50 Low permeability

Buda Limestone 80 Low porosity/low permeability

Del Rio Clay 60 None/primary upper confining unit

Lower Cretaceous

Edwards Aquifer

Georgetown Formation 20-60 Low porosity/low permeability

Edwards Group

Person Formation

Cyclic and marine members, 

undivided 80-90 Laterally extensive; secondary 

porosity/water-yielding 

Leached and collapsed members, 

undivided 70-90

Porosity developed along fractures 

or faults, permeable beds of collapse 

breccia, biomicrites, honeycombed,

and laterally extensive, one of the 

most permeable

Regional dense member 20-24 Negligible porosity and low 

permeability; vertical barrier

Kainer Formation

Grainstone member 50-60 Cavernous, honeycombed layer and 

interparticle porosity

Kirschberg evaporite member 50-60

One of the most permeable; boxwork 

porosity in brecccia or by burrowed 

zones

Dolomitic member 110-130

Porosity developed along fractures 

or faults, honecombed and laterally 

extensive, water yielding

Basal nodular member 50-60 No permeability in subsurface

HRS Documentation Record 27 Eldorado Chemical Co., Inc.

TXD057567216
Likelihood of Release

Table 9

Hydrogeologic Strata 

Hydrogeologic 

Units

Group, Formation, Member Thickness

(feet) Porosity/Permeability Type

Lower 

confining unit

Upper member of the Glen Rose 

Limestone 

350-500 Relatively impermeable

 Ref. 15, p. 16; Ref. 17, p. 19; Ref. 19, p. 8; Ref. 34, p. 5; Figure 3a of this HRS documentation record 

Regional Hydrogeology 

The aquifers of concern for the site being evaluated for HRS purposes are part of the Edwards Aquifer 

system contained in carbonate-rock units of Lower Cretaceous age (Ref. 18, p. 4; Ref. 33, p. 13). The 

site is located in the artesian zone of the aquifer on the San Marcos platform depositional province 

(Ref. 18, p. 5; Ref. 33, p. 7). The hydrologic unit being evaluated for HRS purposes includes 

interconnected individual aquifers in the Person and Kainer Formations. The Person and Kainer 

Formations compose the Edwards Group (Ref. 19, pp. 8-10). The depositional environment during the 

lower Cretaceous period has been defined as a very complex, highly variable carbonate platform 

environment disrupted by erratic sea level fluctuations that were contemporaneous with the deposition 

(Ref. 18, p. 8). The depositional model of the Edwards is characterized as a detached, rimmed 

carbonate platform with layer-cake lithologies and periodic karst development (Ref. 18, pp. 8-9). Two 

separate episodes of subaerial exposure and incipient karsts developed, the first in the middle part of 

the Kainer Formation and the second in the middle to upper parts of the Person Formation (Ref. 18, p. 

9). 

The Edwards Aquifer system in the Balcones Fault Zone is one of the most productive subsurface 

reservoirs of potable water in the world. The Edwards Aquifer system is the sole source of water for 

the San Antonio area, where it provides domestic, public supply, industrial, and agricultural water

(Ref. 20, pp. 54-55). The sources of recharge to the aquifer are seepage from streams draining the Hill 

Country and flowing onto permeable Edwards Group and Devils River Formation outcrops, infiltration 

of precipitation in the outcrop areas, subsurface inflow across the updip margin of the Balcones Fault 

Zone where the underlying Trinity Aquifer is laterally adjacent to downfaulted Edwards strata, and 

diffuse upward leakage from the Trinity Aquifer (Ref. 20, p. 52). Leakage between the shallower, 

water-yielding Austin Group and the Edwards takes place along faults in some places (Ref. 33, p. 37). 

The large transmissivity of the Edwards Aquifer system is indicated by hundreds of highly productive 

wells throughout the San Antonio area. Many yield greater than 1,000 gallons/minute, with 

drawdowns of only a few feet. Large transmissivity is further indicated by small hydraulic gradients, 

large spring discharges, and relatively uniform quality and temperature of water throughout the aquifer 

(Ref. 33, p. 27). 

In Bexar County, the Edwards Aquifer system includes the Kainer and Person Formations in rocks of 

Lower Cretaceous age (Ref. 15, p 17; Ref. 19, p. 5, 7, 8; Ref. 39, pp. 16, 17). The Edwards Aquifer 

system and several of the units that underlie the Eldorado Chemical Co., Inc. site and recharge the 

Edwards Aquifer system, in order of depth, are discussed below.

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Likelihood of Release

Aquifer 1 - Quaternary Alluvium

Although not mentioned in the table above, the Quaternary Alluvium exists in the site area. Quaternary 

alluvium are generally stream terraces which are composed of gravel, sand and silt and yield water of 

good quality (Ref. 15, p. 25). Within the San Marcos platform in the Balcones Fault Zone, the 

Quaternary Alluvium is in hydraulic connection with streams (Ref. 39, p. 19). Within 3 miles of the 

sources, Cibolo Creek supplies water to recharge the Quaternary Alluvium (Ref. 2, p. 1; Ref. 15, p. 25; 

Ref. 23, p. 12). These stream losses account for 60 to 80 percent of the recharge to the Edwards 

Aquifer system in the San Antonio Area, and the rest of the recharge is derived from direct infiltration

in the inter-stream areas (Ref. 39, p. 13).

Aquifer 2 - Austin Chalk

The Austin Group (also known as the Austin Chalk) supplies water for domestic or stock use where 

yields of 500 gpm or more were reported from several wells. Such yields may result when wells have 

been drilled into subsurface caverns. Some of the large yields from the Austin Chalk are believed to 

be obtained where the formation is in hydraulic communication (e.g., faults, secondary porosity) with 

the Edwards Aquifer system (Ref. 15, p. 22).

Based on cross-sections from the Edwards Aquifer system authority, minor faults appear to be present 

within the investigation area (within 2 miles from the center of the contaminant plume) and may 

contribute to the hydraulic communication between the Austin Chalk and the Edwards Aquifer system

(Ref. 15, pp. 7, 8).

Aquifer 3 - Edwards Aquifer System

The seven members of the Person and the Kainer Formations, makeup seven of the eight informal 

hydrogeologic subdivisions of the Edwards Aquifer system (Ref. 19, p. 8). Hydrogeologic subdivision 

VI (Kirschberg evaporite member) appears to be the most porous and permeable subdivision in the 

Kainer Formation (Ref. 19, p. 5; Ref. 39, p. 16). Hydrogeologic subdivision III (Leached and 

Collapsed members, undivided) is the most permeable subdivision in the Person Formation (Ref. 19, p. 

5). Hydrogeologic subdivision II (cyclic and marine members, undivided) is moderately porous and 

permeable with selective porosity (Ref. 25, p. 5). Very permeable zones are distributed throughout 

units II and VII. The most permeable zones occur in honeycombed rocks formed by large rudist molds 

and irregular openings developed in burrowed tidal wackestone deposits (Ref. 39, pp. 4, 21).

Site-specific Hydrogeology

Based on the review of selected drillers logs located in the investigation area (within 2 miles of the soil 

source), the depth to the static water level typically ranges from 155 to 289 feet bgs (Ref. 38, pp. 14, 

17, 22, 23, 47, 100, 113, 145, 149, 152).

Several of the City of Live Oak’s PWS wells range in depth from 874 to 945 feet below DSL (Ref. 38, 

p. 2).

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Likelihood of Release

Aquifer Interconnections

The aquifers within the Edwards Aquifer system being evaluated for HRS purposes, the Person and 

Kainer Formations, are interconnected within the Balcones Fault Zone (Ref. 18, pp. 4, 5, 8; Ref. 19, p. 

5). Although there is heterogeneity in the Edwards Aquifer system due to the lithologic characteristics 

of the different hydrogeologic subdivisions, it appears that hydraulic communication within the aquifer 

is fostered by movement of ground water along vertical or steeply inclined, open fractures that act as 

passageways by which water can enter permeable strata (Ref. 19, p. 8-10; Ref. 39, pp. 13, 21). Water 

moves from fractures into collapsed breccias, burrowed wackestones, and rudist grainstones that have 

significant intrinsic permeability (Ref. 39, pp. 4, 21). Water well reports and drilling logs within the 

investigation area identify karst features and/or fractured limestone conditions along with faulting 

which promotes hydraulic communication within the Edwards Aquifer system (Ref. 15, p. 19; Ref. 19, 

pp. 5, 7; Ref. 38, pp. 15, 18, 23, 55, 63, 64, 65, 67, 74, 75, 91, 92, 101, 102, 114, 115, 134, 146, 147).

Aquifer Discontinuities and Faults

There are no discontinuities that physically transect the entire aquifer within the site’s 4-mile TDL. 

The faults present in the Balcones Fault Zone conduct water and therefore are not discontinuities. 

Regionally, the site falls within the Balcones Fault Zone (Ref. 18, p. 8; Ref. 19, pp. 5, 6, 8). The 

Balcones Fault Zone is a series of en echelon and normal faults, with the downward fault toward the 

coast (Ref. 19, p. 5). Discontinuous heterogeneity occurs in the Edwards Aquifer system where faults 

place rocks of significantly different permeability in laterally adjacent positions (Ref. 39, p. 35).

HRS Documentation Record 30 Eldorado Chemical Co., Inc.

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Likelihood of Release

3.1 LIKELIHOOD OF RELEASE

3.1.1 OBSERVED RELEASE

Based on the geology and hydrogeology located within the vicinity of the Eldorado Chemical Co., Inc. 

facility, the water bearing strata of the Person and Kainer Formations of the Edwards Aquifer system 

are interconnected within two miles of the soil source and form a single hydrologic unit for HRS 

scoring purposes (Ref. 1, Section 3.0.1.2; see section 3.0.1 of this HRS documentation record). An 

observed release cannot be established for the target aquifer that supplies drinking water, the Edwards 

Aquifer system, therefore the Potential to Release factor is to be evaluated (Ref. 1, Section 3.1.1). 

Ground Water Observed Release Factor Value: 0 

Observed Release to the Alluvial Aquifer

Although not to the target aquifer, an observed release has been established to the shallow alluvial 

aquifer (Quaternary Alluvium). 

Ground water samples from monitoring wells were collected using a submersible bladder pump and 

low-stress (low flow), minimal drawdown collection procedures as described in the work plan. The 

submersible pump was decontaminated at the beginning of the sampling event and between each 

sample. Ground water samples from public and private water supply wells were collected directly from 

sampling ports as described in the work plan (Ref. 12, p. 27; Ref. 13, pp. 3, 4, 6, 8, 9, 11, 14-19; Ref. 

44, p. 15). All samples were prepared and preserved using the methods and equipment described in the 

work plan and QAPP (Ref. 44, p. 15). The ground water samples were analyzed using method 

OLM04.2-GC/MS (low level) and collected on April 4, 5, and 6, 2011 (Ref. 11, pp. 24, 38, 52, 59, 75, 

82, 103, 110, 224, 225; Ref. 44, p. 22). As presented below, these wells were sampled during the same 

sampling event and using the same sampling methodology (Ref. 44, pp. 15-17; see Tables 10 and 11 of 

this HRS documentation record). 

The ground water sampling locations identified below were sampled during the SI sampling event that 

took place in April 2011 by the TCEQ Remediation Division. Ground water samples were collected by 

the TCEQ from 8 monitoring wells located on and near the Eldorado Chemical Co., Inc. property (Ref. 

44, pp. 14, 15). The wells that meet observed release criteria are presented below and their locations 

are shown on Figure 2 of this HRS documentation record. 

Table 10 

April 2011 SI Sampling Event - Observed Release Samples

Station ID/ Sample 

Location/Laboratory ID

Well Depth

(feet bgs) /

Depth to Water 

(feet)

Date

(military time) References

GW-02/ MW-05/ 

1104005-05 49.85/ 12.4

04/05/2011

(1545)

Ref. 11, pp. 8, 355; Ref. 12, p. 17; 

Ref. 13, pp. 8, 19; Ref. 14, pp. 1, 4, 

5; Ref. 44, p. 16

GW-03/ MW-06/ 

1104003-03 54.75/ 4.5

04/04/2011

(1120)

Ref. 11, pp. 8, 349; Ref. 12, pp. 3-4; 

Ref. 13, pp. 14, 15; Ref. 14, pp. 1, 

2;Ref. 44, p. 16

HRS Documentation Record 31 Eldorado Chemical Co., Inc.

TXD057567216
Likelihood of Release

Station ID/ Sample 

Location/Laboratory ID

Well Depth

(feet bgs) /

Depth to Water 

(feet)

Date

(military time) References

GW-04/ MW-07/ 

1104003-05 60.05/ 16.97

04/04/2011

(1400)

Ref. 11, pp. 8, 350; Ref. 12, p. 6; 

Ref. 13, p. 16; Ref. 14, pp. 1-3; Ref. 

44, p. 16

GW-05/ MW-08/ 

1104005-01 33.80/ 21.79

04/05/2011

(0925)

Ref. 11, pp. 8, 353; Ref. 12, p. 7; 

Ref. 13, p. 19; Ref. 14, p. 1; Ref. 44, 

p. 16

GW-06/ MW-03/ 

1104003-07 60.55/ 25.59

04/04/2011

(1615)

Ref. 11, pp. 8, 351; Ref. 12, pp. 18, 

21; Ref. 13, pp. 16, 17; Ref. 14, pp. 

1, 3; Ref. 44, p. 16

GW-07/ MW-04/ 

1104003-08 19.78/ 6.86

04/04/2011

(1720)

Ref. 11, pp. 8, 351; Ref. 12, pp. 18, 

21; Ref. 13, p. 17; Ref. 14, pp. 1, 3; 

Ref. 44, p. 16

GW-08/ MW-02/ 04/05/2011 Ref. 11, pp. 8, 353; Ref. 12, p. 17; 

1104005-02 (1112) Ref. 13, p. 18 ;Ref. 14, pp. 1, 4; Ref. 

19.50/ 7.79 44, p. 17

GW-09/ MW-01/ 04/05/2011 Ref. 11, pp. 8, 355; Ref. 12, p. 17; 

1104005-06 (1250) Ref. 13, pp. 18, 19; Ref. 14, pp. 1, 4; 

59.85/ 25.79 Ref. 44, p. 17

bgs = below ground surface

For all hazardous substances but cyanide, the background level to compare against is 0.5 ug/L. The 

background level established for cyanide is 19.8 ug/L and the level to show a significant increase is 

59.4 ug/L (see Table 13 of this HRS documentation record). Ground water samples identified below 

are those meeting HRS observed release by chemical analysis criteria as defined by the HRS (Ref. 1, 

Section 2.3, Table 2-3). Observed release criteria is met when analytical evidence of a hazardous 

substance significantly above background exists and some portion of that increase is attributable to a 

release from the site. 

Table 11 

Ground Water Observed Release Samples

April 2011 Site Inspection Sampling

Evidence

Hazardous

Substance

Client Sample 

ID 

RL*

(ug/L)

Concentration

(ug/L) References

1,1-Dichloroethylene GW-02 0.5 2.1 Ref. 11, pp. 103-104, 355

Chloroform GW-02 0.5 0.7 Ref. 11, pp. 103-104, 355

cis-1,2-Dichloroethylene GW-02 0.5 2.5 Ref. 11, pp. 103-104, 355

Tetrachloroethylene GW-02 0.5 0.5 Ref. 11, pp. 103-104, 355

Trichloroethylene GW-02 250 1370 Ref. 11, pp. 103-104, 355

1,2-Dichloroethane GW-03 0.5 0.9 Ref. 11, pp. 24-25, 349

cis-1,2-Dichloroethylene GW-03 0.5 9.5 Ref. 11, pp. 24-25, 349

Tetrachloroethylene GW-03 0.5 89.2 Ref. 11, pp. 24-25, 349

trans-1,2-Dichloroethylene GW-03 0.5 1.6 Ref. 11, pp. 24-25, 349

Trichloroethylene GW-03 0.5 26.8 Ref. 11, pp. 24-25, 349

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TXD057567216
Likelihood of Release

Evidence

Hazardous

Substance

Client Sample 

ID 

RL*

(ug/L)

Concentration

(ug/L) References

1,1-Dichloroethane GW-04 25 68.0 Ref. 11, pp. 38-39, 350

1,1-Dichloroethylene GW-04 25 90.5 Ref. 11, pp. 38-39, 350

1,4-Dichlorobenzene GW-04 25 534 Ref. 11, pp. 38-39, 350

Benzene GW-04 25 194 Ref. 11, pp. 38-39, 350

Chlorobenzene GW-04 25 248 Ref. 11, pp. 38-39, 350

cis-1,2-Dichloroethylene GW-04 500 33900 Ref. 11, pp. 38-39, 350

Toluene GW-04 25 268 Ref. 11, pp. 38-39, 350

trans-1,2-Dichloroethylene GW-04 25 114 Ref. 11, pp. 38-39, 350

Vinyl Chloride GW-04 25 3820 Ref. 11, pp. 38-39, 350

Naphthalene GW-04 0.5 2.1 Ref. 11, pp. 41, 350

1,1-Dichloroethane GW-05 0.5 1.8 Ref. 11, pp. 75-76, 353

1,4-Dichlorobenzene GW-05 0.5 2.6 Ref. 11, pp. 75-76, 353

Chlorobenzene GW-05 0.5 3.0 Ref. 11, pp. 75-76, 353

cis-1,2-Dichloroethylene GW-05 0.5 1.7 Ref. 11, pp. 75-76, 353

Cyanide GW-05 10 455 Ref. 11, pp. 79, 353

1,1-Dichloroethane GW-06 2.5 6.0 Ref. 11, pp. 52-53, 351

1,1-Dichloroethylene GW-06 250 7860 Ref. 11, pp. 52-53, 351

1,2-Dichloroethane GW-06 2.5 76.0 Ref. 11, pp. 52-53, 351

Tetrachloroethylene GW-06 2.5 2.8 Ref. 11, pp. 52-53, 351

Trichloroethylene GW-06 2.5 7.0 Ref. 11, pp. 52-53, 351

1,1-Dichloroethane GW-07 2.5 26.2 Ref. 11, pp. 59-60, 351

1,1-Dichloroethylene GW-07 250 6580 Ref. 11, pp. 59-60, 351

Benzene GW-07 2.5 13.8 Ref. 11, pp. 59-60, 351

Chloroform GW-07 2.5 2.8 Ref. 11, pp. 59-60, 351

cis-1,2-Dichloroethylene GW-07 2.5 3.7 Ref. 11, pp. 59-60, 351

Trichloroethylene GW-07 2.5 4.1 Ref. 11, pp. 59-60, 351

Vinyl Chloride GW-07 2.5 27.2 Ref. 11, pp. 59-60, 351

1,1-Dichloroethane GW-08 0.5 1.1 Ref. 11, pp. 82-83, 353

cis-1,2-Dichloroethylene GW-08 0.5 0.7 Ref. 11, pp. 82-83, 353

1,1-Dichloroethane GW-09 0.5 0.8 Ref. 11, pp. 110-111, 355

1,1-Dichloroethylene GW-09 0.5 2.8 Ref. 11, pp. 110-111, 353

1,2-Dichloroethane GW-09 0.5 2.2 Ref. 11, pp. 110-111, 353

Note:

ug/L – microgram per liter

RL – Reporting Limit adjusted for sample size and matrix interference (Ref. 11, p. 6)

* RL is equal to the sample quantitation limit (SQL) and is adjusted for sample volume and dilutions as defined in 

the HRS (Ref. 1, Section 1.1; Ref. 11, p. 8; Ref. 45).

One ground water sample was collected during the SI to be used as a background sample. The 

background sample was of the same media, was collected during the same SI, and was analyzed with 

HRS Documentation Record 33 Eldorado Chemical Co., Inc.

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Likelihood of Release

the same analytical methods as the other ground water samples. The background ground water sample 

GW-10 was collected from San Antonio Water System (SAWS) Naco Station Well #4. The 

background sample was not collected for ground water samples from the on-property monitoring wells 

due to a lack of distant off-site wells representing the same ground water bearing unit (Ref. 44, p. 24). 

Table 12 

April 2011 SI Sampling Event – Background Sample

Station ID/ Sample 

Location/Laboratory ID

Well Depth

(feet bgs) / 

Depth to Water 

(feet)

Date

(military time) References

GW-10/ SAWS Naco 

Station PWS Pump #4/ 

1104006-01 785/ Not Applicable

04/06/2011

(1000) 

Ref. 11, pp. 8, 361; Ref. 12, p. 27; 

Ref. 13, p. 11; Ref. 44, p. 17

bgs = below ground surface

Table 13 – Background Ground Water

April 2011 Site Inspection Sampling

Hazardous

Substance

Evidence

References Client Sample 

ID 

RL*

(ug/L)

Concentration

(ug/L)

1,1-Dichloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Chloroform GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

cis-1,2-Dichloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 224. 361

Tetrachloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 225, 361

Trichloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

1,2-Dichloroethane GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

trans-1,2-Dichloroethylene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

1,1-Dichloroethane GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

1,4-Dichlorobenzene GW-10 0.5 0.5 U Ref. 11, pp. 225, 361

Benzene GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Chlorobenzene GW-10 0.5 0.5 U Ref. 11, pp. 225, 361

Toluene GW-10 0.5 0.5 U Ref. 11, pp. 225, 361

Vinyl Chloride GW-10 0.5 0.5 U Ref. 11, pp. 224, 361

Naphthalene GW-10 0.5 0.5 U Ref. 11, pp. 227, 361

Cyanide GW-10 10 19.8 Ref. 11, pp. 228, 361

Notes:

ug/L – microgram per liter

U – Undetected (Ref. 11, p. 365)

RL – Reporting Limit adjusted for sample size and matrix interference (Ref. 11, p. 6)

* RL is equal to the sample quantitation limit (SQL) and is adjusted for sample volume and dilutions as defined in 

the HRS (Ref. 1, Section 1.1; Ref. 11, p. 8; Ref. 45).

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Attribution

A search for possible off property contamination sources located up-gradient of the sources did not 

identify any facilities within the EPA’s Toxic Release Inventory (Ref. 47, pp. 1-2; Figure 1a of this 

HRS documentation record). EPA’s EnviroMapper did not identify any facilities within the Live Oak 

zip code which uses the contaminants of concern (Ref. 48, pp. 1-9; Figure 1a of this HRS 

documentation record). Many of the hazardous substances being scored in this HRS documentation 

record are also manmade substances. Therefore, due to the lack of off property contamination sources 

and the historic use of such material as halogenated solvent mixtures at the Eldorado Chemical Co., 

Inc. facility, the contamination present in the aforementioned ground water samples is the result of 

facility operations and not ubiquitous throughout the environment. 

3.1.2 POTENTIAL TO RELEASE

As identified above, an observed release has not been documented to the aquifer being evaluated, the 

Edwards Aquifer system. For this reason, the HRS evaluates the potential for this to occur. Since an 

observed release cannot be established to the Edwards Aquifer system, the Potential to Release Factor 

Value is assigned as the Likelihood of Release factor category value (30) (Ref. 1, Section 3.1.3). For 

contamination to reach the Edwards Aquifer system it must pass through several layers (the Austin 

Group, the Eagle Ford Group, the Buda Limestone, and the Del Rio Clay) as shown in section 3.0.1 of 

this HRS documentation record (Ref. 32, p. 13). Minor faults within 2 miles of the site, may 

contribute to hydraulic communication between the Austin Chalk and the Edwards Aquifer system 

(Ref. 15, pp. 7, 8). 

The Potential to Release factor is evaluated based on four factors: containment, net precipitation, depth 

to aquifer, and travel time. 

3.1.2.1 Containment 

A containment factor value is assigned to each source at the site from HRS Table 3-2 (Ref. 1, Section 

3.1.2.1; see section 2.2.1 of this HRS documentation record for Sources 1 and 2). Evidence of a lack of 

a liner at Source 1 and of hazardous substance migration from Source 1 has been documented, so the 

maximum of 10 is assigned (Ref. 1, Section 3.1.2.1). 

3.1.2.2 Net Precipitation 

A net precipitation factor value of 1 is assigned based on computed net precipitation values presented 

in Figure 3-2 of Reference 1 (Ref. 1, Section 3.1.2.2) and the general location of the site within the 

state of Texas (Figure 1a of this HRS documentation record; Ref. 2, p. 1).

3.1.2.3 Depth to Aquifer 

The depth to the aquifer was measured using the City of Live Oak PWS Well Number 4 (PWS ID 

TX0150068, State Well No. 6830409), located approximately 3,600 feet east of Sources 1 and 2 (Ref. 

24, pp. 1-7; Ref. 38, pp. 54-56; Ref. 44, p. 21; Figures 1a and 2 of this HRS documentation record). 

The distance to the lowest known point of contamination at the site is in MW-03 (where sample GWHRS Documentation Record 35 Eldorado Chemical Co., Inc.

TXD057567216
Likelihood of Release

06 was collected) at 60.55 feet (ft) below ground surface (bgs), where 1,2-dichloroethane, 1,1-

dichloroethylene, tetrachloroethylene, and trichloroethylene were detected (see section 3.1.1 and 

Figure 2 of this HRS documentation record; Ref. 44, p. 16). Based on the details of the City of Live 

Oak well 6830409, the top of the Edwards Aquifer system is at 484 ft bgs (Ref. 38, pp. 54, 55). 

Therefore the depth to the target aquifer is the distance of the target aquifer from the surface (484 ft. 

bgs) minus the distance to the lowest known point of contamination (60.55 ft bgs) = 423.45 ft bgs. 

The depth to the Edwards Aquifer system is greater than 250 feet, so a value of 1 is assigned (Ref. 1, 

Section 3.1.2.3, Table 3-5).

3.1.2.4 Travel Time 

The lowest known point of contamination at the site is in MW-03 (sample GW-06) at 60.55 feet (Ref. 

44, p. 16). Using the description of City of Live Oak well Number 4, at 60.55 feet bgs there is 

limestone, and the limestone continues until 257 feet, or a total 196.45 feet of limestone under the 

lowest point of contamination (Ref. 24, p. 6; Ref. 38, pp. 54, 55). After the limestone, there is 47 feet 

of chalk, 74 feet of green shale, 56 feet of limestone, then 60 feet of brown clay before the Edwards 

Aquifer system (Ref. 38, pp. 54, 55). Based on HRS Table 3-6, clay and shale have an assigned 

hydraulic conductivity of 10-8 centimeters per second. Since the combined depth of the shale and clay 

layers, which are the layers with the lowest hydraulic conductivity, is greater than 100 feet, but less 

than 500 feet, based on HRS Table 3-7, the lowest value of 1 is assigned (Ref. 1, Section 3.1.2.4, Table 

3-6, Table 3-7; Ref. 38, p. 55). 

3.1.2.5 Calculation of Potential to Release 

The factor values for net precipitation (1), depth to aquifer (1), and travel time (1) are added together 

(3) and multiplied by the factor value for containment (10) to calculate the potential to release factor 

value for the Edwards Aquifer system (30) (Ref. 1, Section 3.1.2.5). 

Potential to Release Factor Value = 30 

HRS Documentation Record 36 Eldorado Chemical Co., Inc.

TXD057567216
Waste Characteristics

3.2 WASTE CHARACTERISTICS

3.2.1 Toxicity/Mobility 

The following toxicity, mobility, and combined toxicity/mobility factor values are associated with the 

hazardous substances found at Sources 1 or 2. 

Table 14 

Toxicity/Mobility of Hazardous Substances 

Hazardous Substance

Toxicity 

Factor

Value

Mobility 

Factor

Value 

(karst)*

Toxicity/

Mobility

(Ref. 1,

Table 3-9) References

1,2,4-Trichlorobenzene

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 39

1,4-Dichlorobenzene

10

1 10 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 18

1,2,4-Trichlorobenzene

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 57

Benzene

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 9

Chlorobenzene

100

1 100 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 12

Chloroform

100

1 100 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 15

Cyanide

10,000

1 10,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 54

cis-1,2-

Dichloroethylene 1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 30

trans-1,2-

Dichloroethylene 100

1 100 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 33

Naphthalene

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 36

1,1-Dichloroethane

10

1 10 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 21

1,1-Dichloroethylene

10

1 10 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 27

1,2-Dichloroethane

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 24

Tetrachloroethylene

100

1 100 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 42

Toluene

10

1 10 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 45

Trichloroethylene

1,000

1 1,000 Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 48

Vinyl Chloride 10,000 1 10,000

Ref. 1, Sections 2.4.1.2, 3.2.1; Ref. 

3, p. 51

HRS Documentation Record 37 Eldorado Chemical Co., Inc.

TXD057567216
Waste Characteristics

* The Person and Kainer Formations of the Edwards Aquifer system compose the target aquifer and are karst aquifers (Ref. 

9, pp. 5-7; see section 3.0.1 of this HRS documentation record).

The hazardous substances with the highest toxicity/mobility factor value available to the ground water 

migration pathway are cyanide and vinyl chloride (10,000) (Ref. 3, pp. 51, 54; Ref. 11, pp. 59-60, 

351). 

Toxicity/Mobility Factor Value (Ref. 1, Section 3.2.1.3, Table 3-9): 10,000 

3.2.2 HAZARDOUS WASTE QUANTITY

Table 15 

Hazardous Waste Quantity

Source No. Source Type

Current Source 

Hazardous Waste 

Quantity

1 Contaminated Soil 5.929

2 Unallocated Source (Other) > 0, but unknown

 Sum of Values: 5.929

Although remediation activities occurred at the facility between 1984 and 1986, continued waste 

violations occurred after those activities, with violations noted in 1993, 1999, and 2001 and an 

enforcement action occurring in 2007 (Ref. 5, pp. 5-14; Ref. 44, pp. 11-12). Furthermore, the soil from 

which the Source 1 samples were collected in 2001 has not been removed. Therefore the removal 

action was not used in determining the Hazardous Waste Quantity factor value. According to HRS 

Section 2.4.2.2, a Hazardous Waste Quantity factor value of 10 was assigned due to the following: the 

hazardous constituent quantity is not adequately determined for all the sources; no targets for the 

Ground Water Migration Pathway are subject to Level I or Level II concentrations; there has been no 

removal action; and the value of 10 is greater than the value that would be assigned from HRS Table 

2-6 (Ref. 1, Section 2.4.2.2). 

 

Hazardous Waste Quantity Factor Value (Ref. 1, Section 2.4.2.2): 10 

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 10 was 

multiplied by the highest Toxicity/Mobility Value of 10,000, resulting in a product of 100,000 

(1.0E+05). Based on this product, a Waste Characteristics Factor Category Value of 18 was assigned 

from Table 2-7 of Reference 1 (Ref. 1, Section 2.4.3.1). 

Toxicity/Mobility Factor Value: 10,000 

Hazardous Waste Quantity Factor Value: 10

HRS Documentation Record 38 Eldorado Chemical Co., Inc.

TXD057567216
Waste Characteristics

Toxicity/Mobility Factor Value (10,000) × Hazardous Waste Quantity Factor Value (10) = 1 x 105

Waste Characteristics Factor Category Value (Ref. 1, Table 2-7): 18

3.3 Ground Water Pathway Targets 

3.3.1 Nearest Well

If no drinking water wells are subject to Level I or Level II concentrations, the shortest distance to any 

drinking water well from any source at the site with a ground water containment factor value of greater 

than 0 is determined (Ref. 1, Section 3.3.1). The target aquifer (aquifer of concern) that underlies the 

soil source at the site is karst, and the nearest well which draws drinking water is within the same karst 

aquifers, and is within the 4-mile target distance limit (Ref. 15, p. 19; Ref. 18, pp. 4, 5, 8; Ref. 19, pp. 

5, 7; Ref. 38, pp. 15, 18, 23, 55, 63, 64, 65, 67, 74, 75, 91, 92, 101, 102, 114, 115, 134, 146, 147; Ref. 

39, p. 13, 21, 22; Figure 3b of this HRS documentation record). The nearest drinking water well is 

Live Oak 150068D (also called state well 6830409), located between 1⁄2-mile and 1-mile east of the site 

(See Figure 3b of this HRS documentation record), and is drilled in the karst Edwards Aquifer system 

located within the Balcones Fault Zone (Ref. 18, pp. 4, 5, 8-9; Ref. 38, pp. 2, 3, 54-56; Ref. 44, p. 21). 

The Edwards Aquifer system is also called the Balcones Fault Zone Aquifer in some publications due 

to its location within the Balcones Fault Zone (Ref. 18, pp. 4, 5, 8; Ref. 23, pp. 11, 14, 20; Ref. 33, p. 

11). Therefore, according to Reference 1, Section 3.3.1, a value of 20 is selected for the Nearest Well 

Factor Value. 

Nearest Well Factor Value: 20

3.3.2 Population 

3.3.2.1 Level of Contamination 

3.3.2.2 Level I Concentrations

To date, no known ground water targets subject to Level I concentration levels have been identified for 

the ground water pathway. 

Level I Concentrations Factor Value: 0

3.3.2.3 Level II Concentrations 

To date, no known ground water targets subject to Level I concentration levels have been identified for 

the ground water pathway. 

Level II Concentrations Factor Value: 0 

 

HRS Documentation Record 39 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

3.3.2.4 Potential Contamination

The potential contamination factor was evaluated and scored. Active residential public water supply

(PWS) wells were identified from the TCEQ Public Water Supply Database within radii of 0.25 to 0.5, 

0.5 to 1, 1 to 2, 2 to 3, and 3 to 4 miles from the site (Figure 3b of this HRS documentation record; 

Ref. 24, pp. 1-121). All of the target wells are within the Edwards Aquifer system (Ref. 38, pp. 2-3). 

The Edward Aquifer system that underlies the soil source at the site is karst, and the target wells which 

draw drinking water are within the same karst aquifer system (Ref. 15, p. 19; Ref. 18, pp. 4, 5, 8; Ref. 

19, pp. 5, 7; Ref. 38, pp. 2, 3, 15, 18, 23, 55, 64, 67, 75, 92, 102, 115, 134, 147; Ref. 39, p. 13, 21, 22; 

Figure 3b of this HRS documentation record). The potential targets were calculated based on the 

number of users served by each PWS well located within each distance category, and the population 

was allocated to each well as directed by the HRS, and the weighted population assigned from the 

“Karst” portion of Table 3-12 of the HRS (Ref. 1, Sections 3.3.2 and 3.3.2.4, Table 3-12).

0 to 0.25 mile

No active drinking water wells were identified between 0 and 0.25 mile from the site.

0.25 to 0.5 mile

No active drinking water wells were identified between 0.25 and 0.5 mile from the site.

0.5 to 1 mile

Between 0.5 and one mile from the site, two active PWS wells serve the City of Live Oak (State Wells 

6830409 and 6830402 were identified (Figure 3b of this HRS documentation record; Ref. 38, pp. 2-3). 

(Note: For each state well number the associated public water system well number is identified in 

Table 16 of this HRS documentation record.)

Both wells in this distance interval (G0150068B and G0150068D) serve the City of Live Oak PWS 

(PWS ID TX0150068). The City of Live Oak PWS consists of four active wells that together serve a 

total of 10,531 people. None of the wells supply over 40% to the total volume of the system, so each 

well serves 2,632.75 people. Therefore, wells G0150068B and G0150068D serve a total of 5,265.5 

people (Ref. 24, pp. 2-7; Ref. 25, p. 1).

1 to 2 miles

Between one and two miles from the site, five active PWS wells were identified serving the City of 

Selma (State Well 6830520), the City of Universal City (State Wells 6830512 and 6830522), and the 

City of Live Oak (State Wells 6830401 and 680403) (Figure 3b of this HRS documentation record; 

Ref. 38, pp. 2-3).

Two of the wells in this interval, wells G0150068A and G0150068C, serve the City of Live Oak PWS 

(PWS ID TX0150068). The City of Live Oak PWS consists of four active wells that together serve a 

total of 10,531 people. None of the wells supply over 40% to the total volume of the system, so each 

HRS Documentation Record 40 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

well serves 2,632.75 people (Ref. 24, pp. 2-7; Ref. 25, p. 1). Therefore, wells G0150068A and 

G0150068C serve a total of 5,265.5 people.

Two of the wells in this interval, wells G0150009D and G0150009F, serve the City of Universal City 

PWS (PWS ID TX0150009). The City of Universal City PWS consists of seven active PWS wells in 

the Edwards Aquifer system and one supply source located in the Carrizo Aquifer supplied by the 

Schertz-Seguin pipeline from a separate PWS that together serve a total of 19,155 people. None of the 

sources supply over 40% to the total volume of the system, so each source serves 2,394.37 people 

(Ref. 17, p. 1; Ref. 24, pp. 8-14; Ref. 26, p. 1). Therefore, Wells G0150009D and G0150009F serve a 

total of 4,788.75 people.

One of the wells in this interval, well G0150492A (also identified as Yellowbark or Mount Crest Rd., 

since it is located near the corner of Yellow Bark Blvd. and Mountcrest Dr.) serves the City of Selma 

PWS (PWS ID TX0150492). The City of Selma PWS consists of two active PWS wells in the 

Edwards Aquifer system and one supply source located in the Carrizo Aquifer supplied by the SchertzSeguin pipeline from a separate PWS that together serve a total of 5,551 people. According to the 

Selma City Engineer, 40% of the city’s water use in 2015 was taken from the two wells, with the 

remaining taken from the Schertz-Seguin pipeline. Of the water produced from the two wells, 45% 

was taken from well G0150492A, with the remainder taken from well G0150492B (Ref. 17, p. 1; Ref. 

24, pp. 15-19; Ref. 27, p. 1). Therefore, well G0150492A serves 999.18 people.

2 to 3 miles

Between two and three miles from the site, 11 active PWS wells were identified serving the City of 

Converse (State Well 6830714), the City of Universal City (State Well 6830516), City of Selma (State 

Well 6830214), the San Antonio Water System (SAWS) Northeast PWS (formerly referred to as 

BWMD (State Well 6830719), and SAWS (State Wells 6829608, 6829609, 6829610, 6829611, 

6829612, 6829613, and 6829614) (Figure 3b of this HRS documentation record; Ref. 38, pp. 2-3).

One of the wells in this interval, well G0150009E, serves the City of Universal City PWS (PWS ID 

TX0150009). The City of Universal City PWS consists of seven active PWS wells in the Edwards 

Aquifer system and one supply source located in the Carrizo Aquifer supplied by the Schertz-Seguin 

pipeline from a separate PWS that together serve 19,155 people. None of the sources supply over 40% 

to the total volume of the system, so each source serves 2,394.37 people. Therefore, well G0150009E 

serves a total of 2,394.37 people (Ref. 17, p. 1; Ref. 24, pp. 8-14; Ref. 26, p. 1).

Two of the wells in this interval, wells G0150047C and G0150047D, serve the City of Converse PWS 

(PWS ID TX0150047). G0150047C is an inactive well and used during emergencies only. The City of 

Converse PWS consists of three active PWS, but only two of the wells are used to serve a total of 

24,921 people. According to the City of Converse Utilities Department Office Manager, 75% of the 

PWS water is supplied by well G0150047D. Therefore, well G0150047D serves 18,690 people (Ref. 

24, p. 26-31; Ref. 28, pp. 1-2).

One of the wells in this interval, well G0150492B, serves the City of Selma PWS (PWS ID 

TX0150492). The City of Selma PWS consists of two active PWS wells and one supply source located 

in the Carrizo Aquifer supplied by the Schertz-Seguin pipeline that together serve 5,551 people. 

HRS Documentation Record 41 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

According to the City of Selma City Engineer, 40% of the City’s water use is supplied by the two 

wells, with the remaining 60% supplied by the Schertz-Seguin pipeline. Of the water produced from 

the two wells, 55% was taken from G0150492B. Therefore, well G0150492B serves 1,221.22 people 

(Ref. 17, p. 1; Ref. 24, pp. 15-19; Ref. 27, p. 1).

One of the wells in this interval, G0150084E, serves the SAWS Northeast PWS (formerly called 

BWMD; PWS ID TX0150084). The SAWS Northeast PWS consists of three active wells and one 

additional surface water source that together serve 66,423 people. None of the sources supply more 

than 40% of the total volume of the system, so each source serves 16,605.75 people. Therefore, well

G0150084E serves a total of 16,605.75 people (Ref. 24, pp. 32-41; Ref. 29, pp. 1-3).

Seven of the wells in this interval, wells G0150018CC, G0150018CD, G0150018CE, G0150018CF, 

G0150018CG, G0150018CH, and G0150018CI (also called the NACO wells), serve the San Antonio 

Water System PWS (PWS ID TX0150018). The San Antonio Water System consists of 113 active 

operating wells that serve a total population of 1,659,291 people (Ref. 24, pp. 42-108). None of the 

wells supply more than 40% to the total volume, therefore each well supplies 14,683.99 people (Ref. 

29, pp. 1-3). Wells G0150018CC, G0150018CD, G0150018CE, G0150018CF, G0150018CG, 

G0150018CH, and G0150018CI serve a total of 102,787.93 people (Ref. 24, pp. 51, 52, 85, 86).

3 to 4 miles

Between three and four miles from the site, 11 active PWS wells were identified serving the City of 

Converse (State Well 6830810), the City of Universal City (State Wells 6830506, 6830509, 6830518, 

and 6830519), Bexar County (State Well 6829927), SAWS (State Wells 6829913, 6829915, and 

6829926), Alamo Cement Co. (State Well 6830115), and BIGS 208 (State Well 6830233) (Figure 3b 

of this HRS documentation record; Ref. 38, pp. 2-3).

Four of the wells in this interval, wells G0150009A, G0150009C, G0150009G, and G0150009H, serve 

the City of Universal City PWS (PWS ID TX0150009). The City of Universal City PWS consists of 

seven active PWS wells in the Edwards Aquifer system and one supply source located in the Carrizo 

Aquifer supplied by the Schertz-Seguin pipeline from a separate PWS that together serve 19,155 

people. None of the sources supply over 40% to the total volume of the system, so each source serves 

2,394.37 people. Therefore, wells G0150009A, G0150009C, G0150009G, and G0150009H serve a 

total of 9,577.48 people (Ref. 17, p. 1; Ref. 24, pp. 8-14; Ref. 26, p. 1).

One of the wells in this interval, well G0150047A, serves the City of Converse PWS (PWS ID 

TX0150047). The City of Converse PWS consists of three active PWS wells, but only two wells are 

used to serve a total of 24,921 people. According to the City of Converse Utilities Department Office 

Manager, 25% of the PWS water is supplied by well G0150047A. Therefore, well G0150047A serves 

6,230.25 people (Ref. 24, p. 26-31; Ref. 28, pp. 1-2).

One of the wells in this interval, well G0150106D, serves the Bexar County WCID 10 PWS (PWS ID 

TX0150106). The Bexar County WCID 10 PWS consists of four active PWS wells that together serve 

a total of 6,112 people. According to the General Manager of the Bexar County WCID 10 PWS, well 

G0150106D contributes approximately 14.5% to the total volume of the system (Ref. 24, pp. 109-114; 

Ref. 30, p. 1). Therefore, well G0150106D serves 886.24 people. 

HRS Documentation Record 42 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

One of the wells in this interval, well G0150459C, serves the Alamo Cement Company and nonresidential workers (PWS ID TX0150459). The Alamo Cement Company consists of one PWS well 

which serves 130 people (Ref. 24, pp. 115-118). 

One of the wells in this interval, well G0460253A, serves the BIGS 208 store and non-residential 

workers (PWS ID TX0460253). The BIGS 208 consists of one PWS well which serves 150 people 

(Ref. 24, pp. 119-121). 

Three of the wells in this interval, wells G0150018AI, G0150018AJ, and G0150018CZ (also called the 

Randolph wells), serve the San Antonio Water System PWS (PWS ID TX0150018). The San Antonio 

Water System consists of 113 active operating wells that serve a total population of 1,659,291 people 

(Ref. 24, pp. 42-108). None of the wells supply more than 40% to the total volume, therefore each 

well supplies 14,683.99 people, for a total of 44,051.97 people (Ref. 24, pp. 51, 52, 74, 75; Ref. 29, pp. 

1-3). 

Table 16 

Potential Population Targets 

DistanceDistance 

Category 

(miles)

PWS

State Well 

No./ PWS 

Well No.

Population 

(individuals)

Population 

subtotal

weighted 

population 

value (karst) 

Ref. 1, Table 3-

12

0.5 to 1 Live Oaka

6830409/

G0150068B 2,632.75

5,265.5 2,607 6830402/

G0150068D 2,632.75

1 to 2

Live Oaka

6830401/

G0150068A 2,632.75

11,053.42 8,163

6830403/

G0150068C 2,632.75

b Universal City

6830522/

G0150009D 2,394.37

6830512/

G0150009F 2,394.37

c Selma 6830520/

G0150492A 999.18

2 to 3

b Universal City 6830516/

G0150009E 2,394.37

138,378.12 81,623

d Converse 6830714/

G0150047D 18,690

c Selma 6830214/

G0150492B 1,221.22

SAWS 

Northeaste

6830719/

G0150084E 13,284.6

SAWSf

6829608/

G0150018CC 14,683.99

6829609/

G0150018CD 14,683.99

HRS Documentation Record 43 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

DistanceDistance 

Category 

(miles)

PWS

State Well 

No./ PWS 

Well No.

Population 

(individuals)

Population 

subtotal

weighted 

population 

value (karst) 

Ref. 1, Table 3-

12

6829610/

G0150018CE 14,683.99

2 to 3 SAWSf

6829611/

G0150018CF 14,683.99

6829612/

G0150018CG 14,683.99

6829613/

G0150018CH 14,683.99

6829614/

G0150018CI 14,683.99

3 to 4

b Universal City

6830509/

G0150009A 2,394.37

61,115.69 26,068

6830506/

G0150009C 2,394.37

6830518/

G0150009G 2,394.37

6830519/

G0150009H 2,394.37

d Converse 6830810/

G0150047A 6,230

Bexar County 

WCID 10 

Windcrestg

6829927/

G0150106D 886.24

Alamo Cement h Co.6830115/

G0150459C 130

Bigs 208i 6830233/

G0460253A 150

SAWSf

6829913/

G0150018AI 14,683.99

6829915/

G0150018AJ 14,683.99

6829926/

G0150018CZ 14,683.99

Total: 118,461

a. Ref. 24, pp. 2-7; Ref. 25, p. 1 f. Ref. 24, pp. 85-86; Ref. 29, pp. 1-3 

b. Ref. 24, pp. 8-14; Ref. 26, p. 1 g. Ref. 24, pp. 109-114 Ref. 30, p. 1

c. Ref. 24, pp. 15-19; Ref. 27, p. 1 h. Ref. 24, pp. 115-118

d. Ref. 24, p. 26-31; Ref. 28, pp. 1-2 i. Ref. 24, pp. 119-121

e. Ref. 24, pp. 32-41; Ref. 29, pp. 1-3 

Sum of Distance-Weighted Population Values: 118,461 (karst) 

Sum of Distance-Weighted Population Values/10 (Ref. 1, Section 3.3.2.4): 11,846.1 

Potential Contamination Factor Value: 11,846 

Population Factor Value (Ref. 1, Section 3.3.2.5) = 11,846

HRS Documentation Record 44 Eldorado Chemical Co., Inc.

TXD057567216
Ground Water Pathway Targets

3.3.3 Resources

Resources have not been evaluated at this time, since drinking water wells score the site and evaluating 

them would not affect the overall score.

Resources Factor Value: 0

3.3.4 Wellhead Protection Area

The wellhead protection areas of the SAWS PWS wells are within the 4-mile TDL of the site, and 

therefore a value of 5 has been assigned (Ref. 1, Section 3.3.4, Ref. 34, pp. 6-7).

 Wellhead Protection Area Factor Value: 5

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 (20), population (11,846), resources (0), and Wellhead Protection Area (5) (Ref. 1, 

Section 3.3.5).

Calculations: 20 + 11,846 + 0 + 5 = 11,871

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 (30), waste characteristics (18), and targets (11,846). Divide by 82,500, the 

resulting value (maximum value 100) is assigned as the ground water migration pathway score (Ref.1, 

Section 3.4).

Calculations: (30 x 18 x 11,871) / 82,500 = 77.70

3.5 Calculation of Ground Water Migration Pathway Score

The Ground Water Migration Pathway Score assigned based on the highest ground water migration 

score calculated for an aquifer underlying sources at the site. For the aquifer being evaluated, the 

Edwards Aquifer system, a value of 77.70 is assigned.

HRS Documentation Record 45 Eldorado Chemical Co., Inc.

TXD057567216
Figure References 

Figure References

Figure 1a: 

Base Map Source* 2013 National Geographic Society, i-cubed

*Map annotated by EPA START-3 on November 2015 to depict site location (Ref. 2, p. 1).

Figure 1b:

Base Map Source* 2013 National Geographic Society, i-cubed

*Map annotated by EPA START-3 on November 2015 to depict site location (Ref. 2, p. 1).

Figure 1c: 

Base Map Source* Esri, HERE, DeLorme, USGS, Intermap, increment P Corp., NRCAN, Esri Japan, 

METI, Esri China (Hong Kong), Esri (Thailand), TomTom, MapmyIndia, OpenStreetMap 

contributors, and the GIS User Community

*Map Annotated by EPA START-3 in November 2015 to depict site location and surrounding 

properties (Ref. 10, p. 28; Ref. 44, pp. 7, 9).

Figure 2: 

Base Map Source* Esri, HERE, DeLorme, USGS, Intermap, increment P Corp., NRCAN, Esri Japan, 

METI, Esri China (Hong Kong), Esri (Thailand), TomTom, MapmyIndia, OpenStreetMap 

contributors, and the GIS User Community

*Map Annotated by EPA START-3 in February 2016 to depict site features, source locations and 

monitoring wells (Ref. 5, p. 28; Ref. 7, p. 3; Ref. 10, p. 28; Ref. 43, p. 11; Ref. 44, pp. 7, 10, 15-20).

Figure 3a:

Base Map Source* Texas Natural Resources Information System. Geologic Database of Texas 

downloaded from: http://tnris.org/data-catalog/geology/geologic-database-of-texas/

*Map annotated by EPA START-3 in November 2015 to depict site location (Ref. 2, p. 1; Ref. 4, p. 2; 

Ref. Ref. 16, pp. 1-3).

Figure 3b:

Base Map Source* Esri, HERE, DeLorme, USGS, Intermap, increment P Corp., NRCAN, Esri Japan, 

METI, Esri China (Hong Kong), Esri (Thailand), TomTom, MapmyIndia, OpenStreetMap 

contributors, and the GIS User Community, 

http://services.arcgis.com/eFZ8AUHBMZMeuwpt/arcgis/rest/services/Texas_Aquifers/FeatureServer

The Texas Water Development Board (TWDB) Groundwater Database (GWDB),

http://www.edwardsaquifer.org/maps/shape-maps.php

The Edwards Aquifer Maps webpage

HRS Documentation Record 46 Eldorado Chemical Co., Inc.

TXD057567216
Figure References 

*Map Annotated by EPA START-3 in March 2016 to depict well locations (Ref. 24, pp. 1-121; Ref. 

38, pp. 2-3; see section 3.3.2.4, Potential Contamination, of this HRS documentation record).

HRS Documentation Record 47 Eldorado Chemical Co., Inc.

TXD057567216
Copyright:© 2013 National Geographic Society, i-cubed

Site Location

TDD NO:19/WESTON-042-16-0001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE PURPOSES ONLY AND SHOULD NOT BE USED, 

AND IS NOT INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FIGURE 1a

REGIONAL LOCATION MAP

EL DORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

20406.012.019.0968.01 AS SHOWN

FILE: I:\GIS_Projects\Brownm\Eldorado Chemical\mxd\Figure 1a Regional Location Map.mxd 10:08:18 AM 3/16/2016 BROWNM

NOVEMBER 2015

DATE PROJECT NO SCALE

US EPA REGION 6

024

Miles
Copyright:© 2013 National Geographic Society, i-cubed

TDD NO:19/WESTON-042-16-0001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE PURPOSES ONLY AND SHOULD NOT BE USED, 

AND IS NOT INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FIGURE 1b

SITE TOPOGRAPHIC MAP

EL DORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

20406.012.019.0968.01 AS SHOWN

FILE: I:\GIS_Projects\Brownm\Eldorado Chemical\mxd\Figure 1b Site Topographic Map.mxd 9:56:11 AM 11/3/2015 BROWNM

NOVEMBER, 2015

DATE PROJECT NO SCALE

US EPA REGION 6

0 800 1,600

Feet

Legend

Property Boundary

10-Meter Topographic Lines
TDD NO:19/WESTON-042-16-0001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE PURPOSES ONLY AND SHOULD NOT BE USED, 

AND IS NOT INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FIGURE 1c

SITE LOCATION AND

SURROUNDING LAND USE MAP

EL DORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

20406.012.019.0968.01 AS SHOWN

FILE: I:\GIS_Projects\Brownm\Eldorado Chemical\mxd\Figure 1c Site Location and Surrounding Land Use.mxd 10:05:42 AM 11/3/2015 BROWNM

NOVEMBER, 2015

DATE PROJECT NO SCALE

US EPA REGION 6

0 400 800

Legend Feet

Property Boundary

Greenridge North 

Neighborhood

TAS Environmental

Hensley Property

Boat and

RV Storage

Former Plastics Recycler

C6 Disposal

Bridlewood

Neighborhood

Nearest Residence
B-8

B-6

B-10

PSG-3

PSG-4

PSG-5 PSG-18

PSG-10

B-15

B-13

B-14

B-7

PSG-16

B-1

TDD NO:19/WESTON-042-16-0001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE PURPOSES ONLY AND SHOULD NOT BE USED, 

AND IS NOT INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FIGURE 2

SOURCE AREA MAP

EL DORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

20406.012.019.0968.01 AS SHOWN

FILE: I:\GIS_Projects\Brownm\Eldorado Chemical\mxd\Figure 2 Source Area Map_0219.mxd 2:58:52 PM 2/19/2016 BROWNM

FEBRUARY, 2016

DATE PROJECT NO SCALE

US EPA REGION 6

0 200 400

Feet

Legend

Property Boundary Soil Samples Collected in 2001

Background Soil Sample Collected in 2011 

Pasive Soil Gas Samples Collected in 2013

PSG_Background

Source 1

Source 2

Monitoring Wells Associated with Source 2

Former Septic Tank

Former Leach Field

Storage Shed

Pratt and Whitney Room

Loading Dock

Laboratories and Offices

Secondary 

Containment

Drain

Former Product Storage

Kiln Room

MW-05

MW-03

MW-04

MW-01

MW-02

MW-06

MW-07

MW-08

Powder Room

SO-12/SO-13
Ked

Ked

Kpg

Kbd

Kbd

Kau

Qt

Kau

Kbd

Qal

Qal

Kau

Kpg

Kpg

Qle

Knb

Kau QTu

Qle

Qle

TDD NO:19/WESTON-042-16-0001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE PURPOSES ONLY AND SHOULD NOT BE USED, 

AND IS NOT INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FIGURE 3a

REGIONAL GEOLOGY MAP

EL DORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

20406.012.019.0968.01 AS SHOWN

FILE: I:\GIS_Projects\Brownm\Eldorado Chemical\mxd\Figure 3a Regional Geology Map.mxd 2:56:55 PM 11/3/2015 BROWNM

NOVEMBER, 2015

DATE PROJECT NO SCALE

US EPA REGION 6

0 6,000 12,000

Feet Legend

Site

Faults

Kau - Austin Chalk

Kbd - Buda Limestone

Ked - Edwards Limestone

Knb - Navarro Group and Marlbrook Marl

Kpg -Pecan Gap Chalk

QTu -Uvalde Gravel

Qal - Eagle Ford Group

Qle - Leona Formation

Qt - Fluviatile terrace deposits
City of Live Oak

State Well # 6830409

City of Live Oak

State Well # 6830402

City of Live Oak

State Well # 6830401

San Antonio Water System

State Well #s 6829608

6829609

6829610

6829611

6829612

6829613

6829614

City of Live Oak

State Well # 6830403

City of Converse

State Well # 6830714

State Well # 6830715

City of Selma

State Well # 6830520

Alamo Cement Co.

State Well # 6830115

San Antonio Water Sys.

State Well #s 6829913

6829915

6829926

SAWS- Northeast

State Well # 6830719

City of Converse

State Well # 6830810

City of Universal City

State Well # 6830512

State Well # 6830522

City of Universal City

State Well #s 6830509

6830518

6830519

City of Universal City

State Well # 6830506

City of Selma

State Well # 6830214

City of Universal City

State Well # 6830516

Artesian

Zone

Recharge

Zone

Recharge

Zone

FIGURE 3b

PUBLIC WATER SUPPLY WELLS

WITHIN 4-MILE TARGET DISTANCE

LIMIT MAP

ELDORADO CHEMICAL CO., INC.

LIVE OAK, BEXAR COUNTY, TEXAS

0 1.5 3

Miles

LEGEND

Public Water Supply Wells

Site (Boundaries of Sources)

0.25 to 4-mile Target Distance Limit

Major Aquifers

CARRIZO

EDWARDS

EDWARDS-TRINITY

GULF_COAST

HUECO_BOLSON

OGALLALA

PECOS VALLEY

SEYMOUR

TRINITY

Aquifer Zone

Drainage Area

Recharge Zone

Artesian Zone

20406.012.019.0968.01 AS SHOWN

TDD NO: 19/WESTON-042-16-001

EPA ID NO: TXD057567216

CONTRACT NO: EP-W-06-042

DISCLAIMER: THIS FIGURE IS PREPARED FOR REFERENCE

 PURPOSES ONLY AND SHOULD NOT BE USED, AND IS NOT

 INTENDED FOR, SURVEY OR ENGINEERING PURPOSES.

FILE: I:\GIS_Projects\Brownm\Templates\EPA-Letter-Landscape.mxd 4:12:19 PM 5/29/2012 DUTTR

MARCH, 2016

DATE PROJECT NO SCALE

US EPA REGION 6

Bigs 208

State Well # 6830233

Bexar County WCID#10

State Well # 6829927

4-mile TDL

3-mile TDL

2-mile TDL

1-mile TDL

0.5-mile TDL

0.25-mile TDL