### 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, Sec tion 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, Sec tion 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 a vailable at this time, evaluation of the surface water migration pathway would not affect the listing decision (Ref. 1, Sec tion 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 t he 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 hazard ous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a ha zardous substance has been "deposited, stored, disposed, or placed, or has otherwise come to be located." Generally, HRS scoring and the subsequen t listing of a release merely represent the initial determination that a certain area may need to be addresse d 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 sequent ial 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 77 th 

### Regular Legislative Se ssion.

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

### REF ERENCES 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 . Super fund Chemical Data Matrix (SCDM) ( E xcerpts). 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. Te xas Commission on Environmental Quality. Industrial and Hazardous Waste Notice of Registration Report. Retrieved February 2, 2009. 23 pages.

5. Johns on, Heather D.

, P.G. Re: Environmental Document Review, Eldorado Chemical Company. Raba-Kistner Consultants, Inc. April 13, 2009. 28 pages.

6. Ri ckhoff, Gerry, Bexar County Clerk. Industrial Solid Waste Disposal Site Deed Recordation

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

7. War eing & Associates, Inc. Initial Phase

- II Subsurface Investigation Conducted on El Dorado Chemi cal 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 – 1435 0 Lookout Road, Live Oak, Texas. W&M Environmental Group, Inc. February 24, 2006. 10 p ages.

9. Te xas Commission on Environmental Quality. Photographic Documentation from the Eldorado Chemical Co. Region 13 Investigation on December 19, 2007. 14 pages.

10. Te xas 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. Cav e, Michael. Photographic Documentation Log from the Eldorado Chemical Co. Site Inspection dated April 4 -6 and April 13, 2011. 31 pages.

13. Te xas Commission on Environmental Quality. Field Notes from the Eldorado Chemical Co. Site Inspection Preparation and Site Inspec tion 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 (E xcerpts) . 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 G a llons Coming to San Antonio Via Schertz

Seguin. 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, Norther n Bexar County, South

Central 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 Aq uifer 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 S imulati on 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 Q uality. 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 Qualit y. 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. T exas Commission on Environmental Quality. Telephone Memo to the File: Call from Mike Cave, TCEQ Pr oject Manager, to Blake Partridge, Superintendent [sic] to the Water Department of Universal City Public Works. June 4, 2012. 1 page.

27. W eston 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. T exas 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 Conver se. May 4 -9, 2012. 2 pages.

29. T exas 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. T exas 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. R eference Number Reserved

32. P edraza, 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. M aclay, 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. S an Antonio Water System. S ource 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. Z ara Environmental, LLC. Final Report for Deep Aquifer Biota Study of the Edwards Aquifer. December 30, 2010. 109 pages.

36. E dwards 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 , 201 6 . Pages: 2.

38. T exas Water Development Board (TWDB) Ground Water Data
– Drill er’s Logs from twenty

one (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/GroundW aterDataViewer 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 Environmen tal Quality. Expanded Site Inspection Report. Eldorado Chemical Co., Inc. June 2014. 405 pages.

41. Geo Strata Environmental. Field N otes 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 , 201 3 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. T exas Commission on Environmental Quality. Site Inspection Report for Eldorado Chemical Co., Inc. Volume 1 of 2 (E xcerpts) . 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. 20406.012.019.09 63.01. January 19, 2016 . Pages: 1.

46. WESTON. Project Note to File. Subject: Eldo rado Chemical Co., Inc . Task Description: Calculating the Area of Source 1 . W.O. NO. 20406.012.019.09 63.01. 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 databa se. 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 . Th e Eldorado facil ity operated as a cleaning products manufacturer at the property from a t 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 sout heastern 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 ident ified 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 Haza rdous 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 chara cteristic 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 wast ewater 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 U 123) , and p henol (waste number U188) (Ref. 4, p. 11 ; Ref. 2 1, 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 in spections 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 d ue 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. TXD0 57567216

### As a result of haz ardous 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 condu cted 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 I nvestigation 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 location s 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

- tr ichlorobenzene, 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 util ized 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. TXD0 57567216

### 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 l ocated within the 4

- mile target distance limit ( TDL ) of the site that are being scored in this HRS evaluation , serving approximately 215,72 2 people in total (Ref. 24 pp. 1 -121 ; Table 1 6 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. TXD0 57567216

### WORKSHEET FOR COMPUTING HRS SITE SCORE

S S 2



### 1. Ground Water Migratio n Pathway Score (S gw 

### ) 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 (S sw 

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

3. Soil Exposure Pathway Score (S s 

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

4. Air Migration Pathway Score (S a 

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

5. Total of S gw 2 

### + S sw 2 

### + S s 2 

### + S a 2 

### 6,037.29 HRS Site Score: Divide the value on line 5 by 4 and take the square root. 38.85

Notes :

S Score S 2 Score squared NS Not scored

Tabl e 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. TXD0 57567216

### HRS Table 3 -1 – Ground Water Migration Pathway Scoresheet

Factor Categories a nd Factors Maximum

Value Value Assigned

Like lihood 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 Ti me 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. To xicity/ Mobility (a) 10,000

5. Hazardous Waste Quantity (a) 10

6. Waste Characteristics 10 0 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. Aq uifer Score [(lines 3 x 6 x 11) ÷ 82,500] (c) 100 77.70 Ground Water Migration Pathway Score:

13. Pathway Score ( S gw ), (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. TXD0 57567216Source 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, p p. 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 genera ted 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 ta nk 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

conc entration 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 p roperty 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 detection s of VOCs and SVOCs contami nation within vadose zone soils ( Ref. 5, p. 9; Ref. 7, pp. 2 -8). No liner was present and native soil contained contamination. Surface and sub surface 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 fou nd 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. TXD0 57567216Source Characterization - Source 1



### 2.4.1 Hazardous Substances

From July 23 to 25, 2001, Wareing and Associates (Wareing), a consultant for Eldorado Chemical Co., In c., 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 -dichl oroethane (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 P hase II Subsurface Investigation was conducted on behalf of the Eldorado Chemical Co., Inc., the data are considered accurate and valid (Ref . 7, p.1).

T o 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 ty pes 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 t o 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 R L* (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

- Dichl oroethylene 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

Tetrachloroeth ylene 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. TXD0 57567216Source Characterization - Source 1

Hazardous Substance Evidence

References Client Sample

ID /Depth of

Sample R L* (mg/kg) Concentration (mg/kg)

1,4

- Dichlorobenzene SO

- 13 (6

- 12”) 0.0059 0.0059 U Ref. 11, pp. 167, 358; R ef. 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. 1 66, 358; Ref. 13, p. 7

Tetrachloroeth ylene 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) R L – 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

c is

- 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’) 0.042 3 Ref. 7, p. 6 1,4

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

c is

- 1,2

- Dichloroethylene B

- 14 (14’) 0.155 Ref. 7, p. 6

Tetrachloroeth ylene 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

c is

- 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. TXD0 57567216Source Characterization - Source 1

Hazardous Substance Evidence

References Sample Location/ Approximate Depth Concentration (mg/kg)

1,4

- Dichlorob enzene B

- 7 (16’) 0.136 Ref. 7, pp. 3, 7

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

Tetrachloroeth ylene 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

Tetrachl oroeth ylene 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

Tetrachloroeth ylene 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
– milligram s 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 s ite ( Figure 2 of this HRS documentation record; Ref. 7, pp. 2, 3; Ref. 43, p. 17).

O n 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 ). F ive samplers were installed near the southeast corner of the facility near the locatio n 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 Br idlewo od 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 t he 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). Th e 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. TXD0 57567216Source Characterization - Source 1



### To establish relative background concentrati ons 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 enviro nment. 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 4 50 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 surv eys during the same sampling event by the same sampling personnel (Ref. 4 3, pp. 18 -22 ).

Summarized below are the background sample results.

Table 3 – Background Soil Gas August 2013 Passive Soil Gas Survey

Hazardous Substance Evidence

R eferences Clie nt 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 – Report ing Limit. The baseline above which results exceed laboratory

- determined limits of precision and accuracy (Ref. 43, p. 1) * The Reporting Limit is a q uantitation l imit 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. TXD0 57567216Source Characterization - Source 1



### Table 4 – Contaminated Soil Source Hazardous Substances August 2013 Passive Soil Gas Survey

H azardous Substance Evidence

R eferences Client Sample ID R L * ( ng ) Concentration (mg/kg)

Tetrachloroeth yl ene PSG

- 03 10 8 J Ref. 43, p p

. 1, 6 , 21, 25 Naphthalene PSG

- 04 25 85 Ref. 43, p p . 1, 7 , 21, 25

Tetrachloroeth yl ene PSG

- 05 10 10 Ref. 43, p p

. 1, 7 , 21, 25

Chloroform PSG

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

Tetrachloroeth yl ene PSG

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

Note:
ng – nanogram R L – Reporting Limit . The baseline above which results exceed laboratory

- determined limit s of precision and
accuracy (Ref. 43, p. 1 ) * The Reporting Limit is a q uantitation l imit 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. TXD0 57567216Source 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 b e 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 Qu antity 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 require ments; 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 wastestr eams 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 w ith 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 assign ed 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 a rea of Source 1 was determined by m easurements 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. TXD0 57567216Source 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. TXD0 57567216Source Characterization - Source 2



### SOURCE 2: SOURCE DESCRIPTION

2.2 Source Characteriz ation : Source 2
– Unallocated Source

2.2.1 Source Identification

Source Description: Source 2 – Unallocated Source

I f a hazardous substance known to be associated with the site cannot be documented as associated with an identified source

, the HRS direct s 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 d emonstrated by the presence of contaminated ground water located under the Eldorado Chemical Co., Inc., property (Figure 2 of this HRS documentation record

, see Table s 6 and 7 below; Ref. 44, pp. 16

- 17 ). The contaminated ground water (see Table 7 below) r esulted from facility operations due to the lack of off property contamination sources

, as shown in s ection 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, p p . 16, 17 ); org anic sludges containing PCE, TCE, and dichlorobenzene (Ref. 4, p. 13 ; Ref. 2 1, 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 environ ment (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 r ecord; 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 include s 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 r ecord ).

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. TXD0 57567216Source Characterization - Source 2



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

Containment Value: 10

2.4.1 Hazardous Substances

A s ite i nspection 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 re spective 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 , p p . 1 7 , 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 submersib le bladder pump and l ow- stress (l ow 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 privat e water supply wells were collected directly from sampling ports as described in the work plan (Ref. 12 , p. 30; Ref. 13 , p p. 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 b elow are the background sample results.

Table 6 – Background Ground Water April 2011 Site Inspection Sampling

H azardous Substance Evidence

R eferences Client Sample ID RL * (ug/L) Concentration (ug/L)

trans

- 1,2

- Dichloroethylene GW

- 10 0.5 0.5 U Ref. 1 1, 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

Note s: ug/L
– microgram per liter U – Undetect ed (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. TXD0 57567216Source 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 5 9.4 ug/L . Ground water samples identified below a re those that are significantly above background as defined by the HRS (Ref. 1, Section 2 .3, Table 2 -3 ) an d at tributable to the site ( s ee s ec tion 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 R L * ( 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 C hloride 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 pre sent 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 Sourc e 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. TXD0 57567216Source 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 Sourc e 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 hazard ous waste quantity value [ (Ref. 1, p. 51591 (Section 2.4.2.1.5)].

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### 24 Eldorado Chemical Co., Inc. TXD0 57567216Source 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 W aste Quantity Value: >0 , but exact quantity unknown

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### 25 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood 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 F ormations are considered one hydrological unit (Ref. 19, p p . 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 rang e 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 perme able 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 A quifer 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 ).

T he 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 w ithin 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,

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### 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

Hydro

geologic

Units Group, Formation, Member Thickness (feet) Porosity/Permeability TypeUpper CretaceousUpper Units Pecan Gap Chalk 350 -500 Southern Bexa r Co. has some bearing strata water

Austin Group 200- 350 Minor aquifer that is interconnected with the Edwards AquiferUpper Confining Units Eagle Ford Group 50 Low permeability

Buda Limestone 80 Low porosity/low permeability

Del Rio Clay 60 Non e/primary upper confining unitLower CretaceousEdwards Aquifer Georgetown Formation 20

- 60 Low porosity/low permeabilityEdwards GroupPerson 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 por osity and low permeability; vertical barrierKainer 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

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### Table 9 Hydrogeologic Strata

Hydro

geologic

Units Group, Formation, Member Thickness (feet) Porosity/Permeability Type

Lower confining unit Upper member of the Glen Rose Limeston e 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 F ormations. The Person and Kainer F orma tions compose the Edwards Group (Ref. 19, pp. 8

- 10). The depositional environment during the lower Cretac eous 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 A quifer system in the Balcones F ault Z one is one of the most productive subsurface reservoirs of potable water in the world. The Edwards Aquifer system is the sol e source of water for the San Antonio area, where it provides domestic, public supply, industrial, and agricultural water ( Ref. 20, pp. 54-55). T he 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 A quifer is laterally adjacent to downfaulted Edwards strata, and diffuse upward leakage from the Trinity A quifer (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, la rge 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 F ormations 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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### Aquifer 1

- Quaternary Allu vium

Although not mentioned in the table above, the Quaternary Alluvium exists in the s ite area. Q uaternary 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 F ault Z one, the Q uaternary Alluvium is in hydraulic connection with streams (Ref. 39, p. 19). Within 3 miles of the sources, Cibolo Creek suppl ies water to recharge the Quaternary Alluvium ( Ref. 2, p. 1; Ref. 15, p. 25; Re f. 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 a uthority, 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 (Kirschber g 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 F ormation (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

- s pecific Hydrogeology

Based on the review of selected drillers logs located in the investigat ion area (within 2 miles of the soil source), the depth to the static water level typically ranges from 1 55 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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### 29 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood 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 collapse d 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 w ithin 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 Bal cones 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 lat erally adjacent positions ( Ref. 39, p. 35).

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### 30 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood 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 Kai ner 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 relea se 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 Releas e 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 a nd 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 suppl y wells were collected directly from sampling ports as described in the work plan (Ref. 12, p. 2 7 ; 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 an d 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 Table s 10 and 11 of this HRS documentation record).

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

St ation ID/ Sample Location/Laboratory ID Well Depth (feet bgs) / Depth to Water (f

eet) Date (military time) References

GW

- 02/ MW

- 05/ 1104005

- 05 49.85/ 12.4 04/05/2011 (1545) Ref. 11, pp. 8, 355; Ref. 1 2, p. 17; Ref. 13, p p . 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

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### 31 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood of Release

St ation ID/ Sample Location/Laboratory ID Well Depth (feet bgs) / Depth to Water (f

eet) 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; Re f. 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

- 0 1 / 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 sampl es 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) Concent ration (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

- Dic hloroethylene 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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### 32 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood of Release

Evidence

Hazardous Substance Client Sample ID RL * (ug/L) Concent ration (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 2 5 534 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

- Dichl oroethylene 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 G W

- 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, 35 5

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 sa mple. The background sample was of the same media, was collected during the same SI, and was analyzed with

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### 33 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood 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 201 1 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/ 110400 6

- 0 1 785 / Not Applicable 04/0 6 /2011 ( 1000 ) Ref . 11, pp. 8, 3 61 ; Ref. 1 2, p. 2 7; Ref. 13, p. 11 ; Ref. 44, p. 17

bgs = below ground surface



### Table 13 – Background Ground Water April 2011 Site Inspection Sampling

H azardous Substance Evidence

R eferences 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 quantitati on 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).

HRS Documentation Record 

### 34 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood of Release



### Attribution

A search for possible off property contamination sources located up

- gradient of the sources did not identif y 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 use s the contaminants of concern (Ref. 48, pp. 1-9; Figure 1a of this HRS documentation record). M any of t he hazardous substances being scored in this HRS d ocumentation record are also manmade substances. Therefore, due to the lack of off property contamination sources and the historic use of such ma terial 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 RELEA SE

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 Edw ards Aquifer system, the Potential to Release Factor Value is assigned as the Likelihood of Release f actor c ategory v alue (30) (Ref. 1, Section 3.1.3). F or contamination to reach the Edwards Aquifer system it must pass through several layers (the Austin G roup, 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 e ach 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 S ource 1 has been documented, s o 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 gen eral 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 TX 0150068, 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 GW

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### 35 Eldorado Chemical Co., Inc. TXD0 57567216Likelihood 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 Aquif er 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 conductiv ity, 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

T he factor values for net preci pitation (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).

Potent ial to Release Factor Value = 30

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### 36 Eldorado Chemical Co., Inc. TXD0 57567216Waste Characteristics



### 3.2 WASTE CHARACTERISTICS

3.2.1 Toxicity/Mobility

T he following toxicity, mobility

, and combined toxicity/mobility factor value s are associated with the hazardous substances found at Sources 1 or 2

.

Table 14 Toxicity/Mobility of Hazardous Substances

H azardous Substance T oxicity Factor Value M obility Factor Value (karst)* T oxicity/ Mobility (Ref. 1, Table 3

- 9) R eferences
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 1 00 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. TXD0 57567216Waste Characteristics

* The Person and Kainer Formations of the Edwards Aquifer system compose the target aquifer and are karst aquifer s (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 path way 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 1 5 Hazardous Waste Quantity

S ource No. S ource 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 v alue 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. TXD0 57567216Waste Characteristics



### Toxicity/Mobility Factor Value (10,000) × Hazardous Waste Quantity Factor Value (10) = 1 x 10 5



### 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 Ba lcones 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 Le vel 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. TXD0 57567216Ground Water Pathway Targets



### 3.3.2. 4 Potential Con tamination

The potential contamination factor was evaluated and scored. Active re sidential 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 3 b 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. 2 5 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 w ell number is identified in Table 1 6 of this HRS documentation record.)

Both wells in this distance interval (G0150068B and G0150068D) serve the City of Live Oak PWS (PWS ID TX 0150068). 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 mi les

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) (Fig ure 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 TX 0150068). The City of Live Oak PWS consists of four active wells that together serve a

t otal 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. TXD0 57567216Ground 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 i n this interval, wells G0150009D and G0150009F, serve the City of Universal City PWS (PWS ID TX 0150009). 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 su pplied 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 TX 0150492). 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 Schertz

Seguin pipeline from a separate PWS tha t 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, 4 5%

was t aken 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 mile s

Between two and three miles from the site, 1 1 active PWS wells were id entified serving the City of Converse (State Well 6830714), the Cit y of Universal City (State Well 68305 1 6 ), 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 G0150009 E , serve s the City of Universal City PWS (PWS ID TX 0150009). Th e 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 so urces supply over 40% to the total volume of the system, so each source serves 2,394.37 people. Therefore, well G0150009E

serve s 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 G015004 7C and G0150047D, serve the City of Converse PWS (PWS ID TX 0150047). 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 peopl e. 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 G01 504 92 B, serves the City of Selma PWS (PWS ID TX 01504 92 ). 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. TXD0 57567216Ground Water Pathway Targets



### According to the City of S elma City Engineer, 40% of the C ity’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, 5 5% was taken from G01504 92 B. Therefore, well G01504 92 B 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, serve s the SAWS Northeast PWS (formerly called BWMD; PWS ID TX 0150084). The SAWS Northeast PWS consists of three active wells and one additio nal 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, w ell G0150084E serve s 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 TX 0150018). 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). We lls G0150018CC, G0150018CD, G0150018CE, G0150018CF, G0150018CG, G0150018CH, and G0150018CI serve a total of 102,787.93 people (Ref. 24, pp. 51, 52, 8 5 , 8 6 ).

3 to 4 mile s

Between three and four miles from the site, 1 1 active PWS wells were identified serv ing the City of Converse (State Well 6830810), the City of Universal City (State Wells 68305 0 6, 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 TX 0150009). The City of Un iversal 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 thi s interval, well G0150047A, serves the City of Converse PWS (PWS ID TX 0150047). 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 Departme nt 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 T X 0150106). 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 t he system ( Ref. 24, pp. 109

- 114; Ref. 30, p. 1 )

. Therefore, w ell G0150106D serves 886.24 people

.

HRS Documentation Record 

### 42 Eldorado Chemical Co., Inc. TXD0 57567216Ground Water Pathway Targets



### One of the wells in this interval, well G0150459C, serves the Alamo Cement Company and non

residential workers (PWS ID TX 0150459). 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 TX 0460253). The BIGS 208 consists of one PWS well which serves 150 pe ople (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 TX 0150018). 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 1 6 Potential Population Targets Distance

Distance 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 Oak a 683040 9/ G0150068B 2,632.75 5,265.5 2,607

6830402/ G0150068D 2,632.75

1 to 2 Live Oak a 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 68 30520/ G0150492A 999.18

2 to 3 b Universal City 6830516/ G0150009E 2,394.37

138,378.12 81,623 d Converse 6830 7 14/ G0150047D 18,690

c Selma 6830214/ G0150492B 1,221.22

SAWS Northeast e 6830719/ G0150084E 13,284.6

SAWS f 6829608/ G0150018CC 14,68 3.99

6829609/ G0150018CD 14,683.99

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### 43 Eldorado Chemical Co., Inc. TXD0 57567216Ground Water Pathway Targets



### Distance

Distance 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 SAWS f 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 6830 509/ 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 Windcrest g 6829927/ G0150106D 886.24

Alamo Cement

h Co. 6830115/ G0150459C 130

Bigs 208 i 6830233/ G 0460253A 150

SAWS f 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 ; Re f. 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

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### 44 Eldorado Chemical Co., Inc. TXD0 57567216Ground 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 o f the SAWS PWS wells are within the 4

- mile TDL of the s ite, 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 Ar ea (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 Cal culation of Ground Water Migration Pathway S core

The Ground W ater Migration Pathway Score assign ed based on the highest ground water migration score calculated for an aquifer underlying sources at the site. For the aquifer being evaluated, the Edwards Aqu ifer system, a value of 77.70 is assigned.

HRS Documentation Record 

### 45 Eldorado Chemical Co., Inc. TXD0 57567216Figur e 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* 20 13 National Geographic Society, i

- cubed

*Map annotat ed by EPA START

- 3 on November 2015 to depict site l ocation ( 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 i n November 2015 to depict site location and surrounding properties ( Ref. 10, p. 28; Ref. 44, pp. 7, 9 )

.
Figure 2 : Base Ma p 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 i n February 2016 t o 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 dow nloaded from: http://tnris.org/data

- catalog/geology/geologic

- database

- of

- texas/

*Ma p annotated by EPA START

- 3 i n 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) Groundw ater Database (GWDB)

, http://www.edwardsaquifer.org/maps/shape

- maps.php The Edwards Aquifer Maps webpage

HRS Documentation Record 

### 46 Eldorado Chemical Co., Inc. TXD0 57567216Figur e References



### *M ap Annotated by EPA START

- 3 i n March 2016 to depict well l ocations ( 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. TXD0 57567216Copyright:© 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

MilesCopyright:© 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 LinesTDD 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

Feet 

### Legend

Property Boundary

Greenridge North

Neighborhood

TAS Environmental

Hensley Property Boat and RV Storage Former Plastics Recycler C6 Disposal

Bridlewood Neighborhood Nearest ResidenceB-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-13Ked

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 depositsCity 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 SCALE DATE PROJECT NO 

## 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