HRS DOCUMENTATION RECORD--REVIEW COVER SHEET

Name of Site: Dorado Ground Water Contamination

EPA ID No.: PRN000201872

Date Prepared: April 2016 

Contact Persons

Site Investigations: Denise Zeno

(212) 637-4319

U.S. Environmental Protection Agency

New York, NY

Documentation Record: Ildefonso Acosta

(212) 637-4344

U.S. Environmental Protection Agency

New York, NY

Pathways, Components, or Threats Not Scored

The surface water, soil exposure, and air pathways were not scored because the listing decision is not significantly

affected by those pathways. The site score is sufficient to list the site on the ground water pathway score.

Document Control No. W0262.1A.00802 
This page has been left blank intentionally.

Document Control No. W0262.1A.00802 
HRS DOCUMENTATION RECORD

Name of Site: Dorado Ground Water Contamination Date Prepared: April 2016

EPA ID No.: PRN000201872

EPA Region: 2 

Street Address of Site:* PR-694 Km 4.5, Dorado, PR 00646 

County and State: Municipality of Dorado, Puerto Rico

General Location in State: northeastern Puerto Rico

Topographic Map: Vega Alta, PR

Latitude:* 18° 25' 47.12" North (18.42975602°) 

Longitude:* 66° 16' 41.95" West (-66.27832042°) 

Site Reference Point: public supply well Maguayo 6

The site consists of a ground water plume with no identified source of contamination. Therefore, the reference point 

for the street address and site latitude/longitude coordinates is one of the contaminated wells near the center of the 

area of observed contamination (i.e., Maguayo 6). The Maguayo 6 well is located at the northeast corner of an

athletic park along PR-694. 

[Figure 1; Refs. 1, p. 51595; 4, p. 1; 5, p. 36; 6, p. 8; 7, pp. 4, 10; 10, pp. 3, 11-12] 

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

documentation record identify the general area where the site is located. They represent one or more locations EPA 

considers to be part of the site based on the screening information EPA used to evaluate the site for NPL listing. 

EPA lists national priorities among the known "releases or threatened releases" of hazardous substances; thus, the 

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

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

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

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.

Scores

Ground Water Pathway 100.00

Surface Water Pathway Not Scored

Soil Exposure Pathway Not Scored

Air Pathway Not Scored

HRS SITE SCORE 50.00

1 
WORKSHEET FOR COMPUTING HRS SITE SCORE

Dorado Ground Water Contamination

S S2

1. Ground Water Migration Pathway Score (Sgw) 100.00 10,000

(from Table 3-1, line 13)

2a. Surface Water Overland/Flood Migration Component Not Scored

(from Table 4-1, line 30)

2b. Ground Water to Surface Water Migration Component Not Scored

(from Table 4-25, line 28)

2c. Surface Water Migration Pathway Score (Ssw) Not Scored

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

3. Soil Exposure Pathway Score (Ss) Not Scored

(from Table 5-1, line 22)

4. Air Migration Pathway Score (Sa) Not Scored

(from Table 6-1, line 12)

5. Total of Sgw2 + Ssw2 + Ss

2 + Sa2 10,000

6. HRS Site Score Divide the value on line 5

 by 4 and take the square root 50.00 

2 
GROUND WATER MIGRATION PATHWAY SCORESHEET

Dorado Ground Water Contamination

GROUND WATER MIGRATION PATHWAY

Factor Categories & Factors

MAXIMUM VALUE VALUE ASSIGNED

Likelihood of Release

1. Observed Release 550 550

2. Potential to Release

2a. Containment 10 not scored

2b. Net Precipitation 10 not scored

2c. Depth to Aquifer 5 not scored

2d. Travel Time 35 not scored

2e. Potential to Release

[lines 2a(2b+2c+2d)]

500 not scored

3. Likelihood of Release 550 550

Waste Characteristics

4. Toxicity/Mobility * 1,000

5. Hazardous Waste Quantity * 100

6. Waste Characteristics 100 18

Targets

7. Nearest Well 50 50

8. Population

8a. Level I Concentrations ** 274,725

8b. Level II Concentrations ** 9,181.63

8c. Potential Contamination ** not scored

8d. Population (lines 8a+8b+8c) ** 283,906.63

9. Resources 5 not scored

10. Wellhead Protection Area 20 not scored

11. Targets (lines 7+8d+9+10) ** 283,956.63 

12. Aquifer Score (lines 3x6x12 divided by 82,500) 100 100

13. Ground Water Migration Pathway Score (Sgw) 100 100.00

* Maximum value applies to waste characteristics category.

** Maximum value not applicable.

3 
REFERENCES

Reference

Number Description of the Reference

1. U.S. Environmental Protection Agency (EPA). Hazard Ranking System, Final Rule. Federal Register, 

Volume 55, No. 241, pp. 51532-51667. December 14, 1990. A complete copy of the rule is available 

at http://www.epa.gov/superfund/hrs-toolbox. [136 pages]

2. EPA. Superfund Chemical Data Matrix (SCDM) Query, Substances: Bromodichloromethane; 

Chloroform; Dichloroethylene, 1,2-cis-; Tetrachloroethylene; and Trichloroethylene; Factor Values 

and Benchmarks: Ground Water Pathway. Query Accessed January 19, 2016. A complete copy of 

SCDM is available at http://www.epa.gov/superfund/superfund-chemical-data-matrix-scdm. [5 pages]

3. EPA. Superfund Site Profile, Dorado Ground Water Contamination (EPA ID: PRN000201872), Site 

Information. Available at

http://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0201872&msspp=. Updated as of February 

19, 2016. [1 page]

4. U.S. Geological Survey (USGS). Vega Alta Quadrangle, Puerto Rico, 7.5-minute Series 

(Topographic). 1969, photorevised 1982. [1 map]

5. Zeno, Denise, EPA. Site Reconnaissance for the Dorado Wells. July 30, 2015. [36 pages]

6. Weston Solutions, Inc. (WESTON). Field Logbook, DCN: W0262.3B.00638, Dorado Ground Water 

Contamination HRS Sampling; with field data sheets and photo log. September 2015. [37 pages]

7. Snyder, Scott, WESTON. Sampling Trip Report, TDD No.: 0004/1507-07, Dorado GW 

Contamination HRS, Document Control No.: W0262.1F.00637. Prepared for EPA. October 2, 2015. 

[41 pages]

8. EPA Region 2 Hazardous Waste Support Branch (HWSB). Dorado GW Contamination; Case 45651; 

SDG BCJQ1 [and BCJR4] -- Regionally Assessed Data. November 13, 2015. [164 pages]

9. Gilliland, Gerry, WESTON. Project Note to Dorado Ground Water Contamination site file, Subject: 

PRASA Analytical Results, Dorado Area Wells, 2002−2015. November 13, 2015. [308 pages]

10. Gilliland, Gerry, WESTON. Project Note to Dorado Ground Water Contamination site file, Subject: 

Well Information and Ground Water Population Apportionment. November 13, 2015. [98 pages]

11. Agency for Toxic Substances & Disease Registry (ATSDR). Tetrachloroethylene – ToxFAQsTM, CAS 

# 127-18-4. September 1997. [2 pages]

12. ATSDR. Trichloroethylene – ToxFAQsTM, CAS # 79-01-6. May 2015. [2 pages]

13. ATSDR. 1,2-Dichloroethene, CAS # 540-59-0, 156-59-2, and 156-60-5, ATSDR ToxFAQs. 

September 1997. [2 pages]

14. Interstate Technology & Regulatory Council (ITRC). Technical/Regulatory Guidelines, Natural 

Attenuation of Chlorinated Solvents in Ground Water: Principles and Practices; appendices not 

included. September 1999. [32 pages]

15. ATSDR. Chloroform – ToxFAQsTM, CAS # 67-66-3. July 2014. [2 pages]

4 
REFERENCES (continued)

Reference

Number Description of the Reference

16. EPA. Technology Transfer Network – Air Toxics Web Site: Chloroform. Downloaded from 

http://www.epa.gov/ttnatw01/hlthef/chlorofo.html on June 15, 2015. [3 pages]

17. Snyder, Scott, WESTON. Project Note to Higuillar Dry Cleaners Project File, Subject: Chloroform. 

July 8, 2015. [1 page]

18. ATSDR. Bromodichloromethane, CAS # 75-27-4, ATSDR ToxFAQs. July 1999. [2 pages]

19. Gómez-Gómez, Fernando, USGS. Estimation of the Change in Freshwater Volume in the North Coast 

Limestone Upper Aquifer of Puerto Rico in the Río Grande de Manatí-Río de la Plata Area between 

1960 and 1990 and Implications on Public-Supply Water Availability. Scientific Investigations Report 

2007-5194. Prepared in cooperation with EPA. 2008. [30 pages]

20. Troester, Joseph W., USGS. Geochemistry and Hydrogeologic Framework of the Saline-Freshwater 

Interface and the Calculation of Net Recharge in the Dorado Area, North-Central Puerto Rico. WaterResources Investigations Report 98−4030. Prepared in cooperation with Puerto Rico Aqueduct and 

Sewer Authority (PRASA). 1999. [43 pages]

21. Veve, Thalia D. and Bruce E. Taggart, USGS, eds. Atlas of Ground-Water Resources in Puerto Rico 

and the U.S. Virgin Islands: Section 2.1.3, Vega Baja−Toa Baja Region by Fernando Gómez-Gómez 

and Thalia D. Veve. Water-Resources Investigations Report 94-4198. Prepared in cooperation with 

EPA. 1996. [20 pages]

22. Renken, Robert, et al, USGS. Geology and Hydrogeology of the Caribbean Islands Aquifer System of 

the Commonwealth of Puerto Rico and the U.S. Virgin Islands: Regional Aquifer-System Analysis—

Caribbean Islands. Professional Paper 1419 [excerpts]. 2002. [68 pages]

23. Guzmán-Ríos, Senén, René García, and Ada Avilés, USGS. Reconnaissance of Volatile Synthetic 

Organic Chemicals at Public Supply Wells Throughout Puerto Rico, November 1984 – May 1985. 

Open-File Data Report 86-63. 1986 [2 pages]

24. Environmental Data Resources, Inc. (EDR). EDR Data MapTM Area Study, Dorado Ground Water 

Contamination, Dorado, PR 00646, Inquiry Number: 4377247.5s. August 11, 2015. [170 pages]

25. Santos Emmanuelli, Rossana. Estudio Sanitario, Inventario Posibles Fuentes de Contaminacion 

Potencial, Pozo Maguayo III, Barrio Maguayo; with translation by WESTON. July 2009. [18 pages]

26. Snyder, Scott, WESTON. Summary Letter Report, Maguayo Site Discovery, Maguayo Ward, Dorado, 

Puerto Rico, Document Control No. 478-2A-ACVO. Prepared for EPA. October 2008. [305 pages]

27. Gilliland, Gerry, WESTON. Project Note to Dorado Ground Water Contamination site file, Subject: 

Historical PRASA Well Status, Dorado Wells. November 30, 2015. [159 pages]

28. EPA. Quick Reference Fact Sheet EPA 540-F-94-028: Using Qualified Data to Document an 

Observed Release and Observed Contamination. Office of Emergency and Remedial Response. 

November 1996. [18 pages]

29. Snyder, Scott, WESTON. Pre-CERCLIS Screening Report, Maguayo Site Discovery, Dorado, Puerto 

Rico, Document Control No. 478-2A-AFOE. Prepared for EPA. January 2010. [377 pages]

5 
REFERENCES (continued)

Reference

Number Description of the Reference

30. Snyder, Scott, WESTON. Site Reassessment Report, Higuillar Dry Cleaners, Dorado, Puerto Rico, 

Document Control No. R2-A-125. Prepared for EPA. July 2015. [156 pages]

31. Carlson, Daniel, WESTON. Preliminary Assessment/Site Inspection Report, Green Point Sign & 

Screen Printing, Dorado, Puerto Rico, Document Control No. 2022-2A-BDXQ. Prepared for EPA. 

April 2014. [175 pages]

32. Snyder, Scott, WESTON. Site Reassessment Report, PRIDCO Block No: L-439-0-97, Dorado, Puerto 

Rico, Document Control No. R2-A-124. Prepared for EPA. August 2015. [390 pages]

33. Gilliland, Gerald V., WESTON. Preliminary Assessment/Site Inspection Report, Adriel Auto, Dorado, 

Puerto Rico, Document Control No. 2026-2A-BDXU. Prepared for EPA. June 2014. [181 pages]

34. Carlson, Daniel, WESTON. Preliminary Assessment/Site Inspection Report, Metal Machining Co. 

Inc, Dorado, Puerto Rico, Document Control No. 2025-2A-BDXT. Prepared for EPA. January 2014. 

[163 pages]

35. Gilliland, Gerald V., WESTON. Preliminary Assessment/Site Inspection Report, Narvaez Cleaners 

and Tailoring, Dorado, Puerto Rico, Document Control No. 2024-2A-BDXS. Prepared for EPA. 

March 2014. [149 pages]

36. Tuero, Caroline, WESTON. Site Reassessment Report, Laundry Espinosa, Dorado, Puerto Rico, 

Document Control No. R2-A-111. Prepared for EPA. July 2015. [145 pages]

37. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building No: T0320-0-56, Dorado, Puerto Rico, Document Control No. 1220-2A-ANPL. Prepared for EPA. June 

2011. [161 pages]

38. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building No: S0050-0-51, Dorado, Puerto Rico, Document Control No. 1221-2A-ANOX. Prepared for EPA. June 

2011. [161 pages]

39. Capriglione, Michele, WESTON. Preliminary Assessment/Site Inspection Report, Former Narvaez 

Cleaners and Tailoring Facility, Dorado, Puerto Rico, Document Control No. 2023-2A-BDXR. 

Prepared for EPA. February 2014. [180 pages]

40. Tuero, Caroline, WESTON. Site Reassessment Report, Edward’s Dry Cleaners Toa Baja, Toa Baja, 

Puerto Rico, Document Control No. R2-A-109. Prepared for EPA. June 2015. [136 pages]

41. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Lot Nos: L-107-

2-64-16/18/19, Dorado, Puerto Rico, Document Control No. 1227-2A-ANRG. Prepared for EPA. 

June 2011. [176 pages]

42. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report (Rev 1), PRIDCO Building 

No. T-1125-0-73 and T-1125-1-79, Dorado, Puerto Rico, Document Control No. 1217-2A-AUKV. 

Prepared for EPA. February 2012. [200 pages]

43. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building No: S0745-0-66, Dorado, Puerto Rico, Document Control No. 1219-2A-AOKN. Prepared for EPA. July 

2011. [167 pages]

6
REFERENCES (continued)

Reference

Number Description of the Reference

44. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Buildings No: S1166-0-74 and S-1166-0-80, Dorado, Puerto Rico, Document Control No. 1225-2A-AOWC. Prepared 

for EPA. August 2011. [194 pages]

45. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building No. T1322-0-88, Dorado, Puerto Rico, Document Control No. 1218-2A-AOKG. Prepared for EPA. July

2011. [150 pages]

46. Snyder, Scott, WESTON. Site Reassessment Report, PRIDCO Buildings No: T-0638-0-66 and T0638-1-67, Dorado, Puerto Rico, Document Control No. R2-A-127. Prepared for EPA. June 2015. 

[150 pages]

47. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Buildings # T0957-0-68/T-0957-1-71/T-0957-2-72/T-1053-0-73/T-1053-1-90, Dorado, Puerto Rico, Document 

Control No. 1224-2A-ANOZ. Prepared for EPA. June 2011. [221 pages]

48. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building Nos: S0838-0-67 and T-0998-0-74, Dorado, Puerto Rico, Document Control No. 1222-2A-APNL. Prepared 

for EPA. August 2011. [216 pages]

49. Chavan, Dipanjali, WESTON. Preliminary Assessment/Site Inspection Report, Former Edward’s Dry 

Cleaners Facility Dorado, Dorado, Puerto Rico, Document Control No. 1309-2A-AOZV. Prepared for 

EPA. September 2011. [42 pages]

50. Snyder, Scott, WESTON. Preliminary Assessment/Site Inspection Report, PRIDCO Building Nos: T0868-0-67 and T-0868-1-69, Dorado, Puerto Rico, Document Control No. 1223-2A-APAB. Prepared 

for EPA. August 2011. [137 pages]

51. Chemtech Consulting Group. CLP Analytical Data Package, SDG No. BCJQ1. October 15, 2015. 

[517 pages]

52. Chemtech Consulting Group. CLP Analytical Data Package, SDG No. BCJR4. October 19, 2015. 

[1,167 pages]

53. Gilliland, Gerry, WESTON. Project Note to Dorado Ground Water Contamination site file, Subject: 

Ground Water Systems in Surrounding Municipalities. February 22, 2016. [12 pages]

7 
SS – Site Summary

SITE SUMMARY

The Dorado Ground Water Contamination (DGWC) site (EPA ID No. PRN000201872) consists of a ground water 

contaminant plume, but the contamination cannot be clearly attributed to any specific source (see below and Section 

3.1.1). The plume is located within the municipality (translated from “municipio”) of Dorado in north-central

Puerto Rico [Figure 1; Refs. 3, p. 1; 4, p. 1; 5, pp. 10, 17−20, 29−36]. The geographic coordinates of the site are 18° 

25' 47.12" north latitude (18.42975602°) and 66° 16' 41.95" west longitude (-66.27832042°), based on the location 

of supply well Maguayo 6 near the center of the area of observed ground water contamination [Figure 1; Refs. 1, p. 

51595; 4, p. 1; 6, p. 8; 7, pp. 4, 10; 10, p. 3]. Figure 1 shows the site location and the area of observed ground water 

contamination.

There are two active water supply systems in Dorado for which ground water wells are primary contributors: 

Maguayo and Dorado Urbano, serving populations of 36,630 and 31,061, respectively [Ref. 10, pp. 1−4, 86−87, 96]. 

At least one well in the Dorado Urbano system has also been used to provide emergency water to other areas of the 

island impacted by drought [Ref. 6, p. 7]. There is also an inactive system, Vivoni, which consisted of the Vivoni 

well located south (i.e., upgradient) of the other wells [Ref. 10, pp. 86−87, 96]. These ground water systems are 

operated as a public utility by Puerto Rico Aqueduct and Sewer Authority (PRASA) [Refs. 7, p. 3; 9, p. 1; 10, pp. 

1−4, 28−30, 96]. Wells in the Maguayo and Dorado Urbano systems have shown detections of volatile organic 

compounds (VOC), primarily tetrachloroethylene (PCE) and trichloroethylene (TCE), since the 1980s [Refs. 9, all 

pages; 23, pp. 1−2; 27, pp. 8−23]. The U.S. Geological Survey (USGS) reported PCE and TCE detections for 

samples collected from Maguayo and Dorado Urbano system wells during the period November 1984 to May 1985 

[Ref. 23, pp. 1−2]. PRASA and Puerto Rico Department of Health (PRDOH) documentation indicates detections for 

the Maguayo and Dorado Urbano system wells for the time period 1996 to 2000 [Ref. 27, pp. 8−23]. PRASA data 

sheets for well samples collected from 2002 to 2015 show the ongoing presence of PCE and TCE in Dorado-area 

ground water [Ref. 9, all pages]. Some reported concentrations have exceeded maximum contaminant levels (MCL), 

and since the 1990s some wells have been closed either temporarily or permanently; the available documentation 

does not cite rationale for the well closures [Refs. 2, pp. 4−5; 10, pp. 1−2, 29−30, 35, 38, 96; 27, pp. 1, 8−23].

Since 2008, EPA has made multiple attempts to identify the source or sources of contamination in the general area 

of the ground water plume. In 2008, EPA launched the Maguayo Site Discovery Initiative (SDI) as an effort to 

identify possible hazardous waste sites in the vicinity of the contaminated wells [Refs. 26, p. 3; 29, pp. 3−4]. After a 

sampling effort confirmed contamination in the Dorado area public supply wells, EPA conducted windshield 

surveys, file searches and reviews, and site reconnaissance activities to identify possible source facilities [Refs. 26, 

pp. 10−15, 144−170; 29, pp. 3−5, 11−28]. Based on the efforts, EPA identified 21 facilities for further investigation

[Ref. 29, p. 28]. Through environmental database searches and reconnaissance activities, EPA also identified other 

industrial facilities in the vicinity of the ground water contamination [Figure 2; Refs. 24, p. 170; 29, pp. 11−20]. 

Figure 2 shows the locations of possible source facilities.

In 2011 and 2013, EPA conducted Preliminary Assessment/Site Inspections (PA/SI) sampling at the 21 facilities

identified for further investigation and, in 2015, EPA conducted Site Reassessment (SR) sampling at 5 of the 

facilities. The sampling efforts included collection of surface soil samples, subsurface soil samples, and ground 

water samples (if ground water was encountered) from each facility; the sampling effort at one active dry-cleaning 

facility also included the collection of soil gas samples [Refs. 30 through 50; see “Other Possible Sources” in 

Section 3.1.1]. Analytical results documented the presence or apparent presence of chlorinated solvents at several 

facilities, whereas there were no detections at other facilities; however, there are no intervening data to clearly 

connect any of the facilities to the supply well contamination (see Figure 2). In addition, the heterogeneous nature 

of the underlying karst limestone aquifer makes it difficult to determine where contamination originates [Refs. 20, 

pp. 13, 32; 22, pp. 49−52, 60−61]. Although some of the possible source facilities are more than 1 mile from the 

contaminated wells, pumping of supply wells in a karst aquifer could affect ground water flow over areas large 

enough to capture contamination from one or more distant sources in several directions [Figure 2; Refs. 20, pp. 3, 

10, 13; 21, pp. 11−15; 22, pp. 8−12, 31, 36, 51−52, 63]. Due to this karst nature of the site, further sampling is not 

likely to identify a source of the contamination and this additional effort would be beyond the scope of an HRS 

evaluation.

In June 2015, PRASA provided VOC analytical results spanning the time frame from May 2012 to May 2015 [Ref. 

9, pp. 301−308]. The most recent available PCE result for Maguayo 5, for a sample collected in August 2013, 

8 
SS – Site Summary

indicated a concentration of 5.9 μg/L, an exceedance of the MCL (5 μg/L) [Refs. 2, p. 4; 9, pp. 301, 304]. A sample 

collected from Maguayo 6 in March 2015 reported a PCE result of 5.6 μg/L, also an exceedance of the MCL; that 

result was followed by a reported concentration of 4.0 μg/L for a sample collected from Maguayo 6 in April 2015

[Ref. 9, p. 305]. Analytical results for Maguayo 7 since 2012 appear to show a general upward trend of PCE 

concentrations, from 2.1 μg/L in September 2012 to the maximum-to-date concentration of 3.5 μg/L in April 2015

[Ref. 9, pp. 305−306]. A single result for Maguayo 3 in January 2013 shows a similar concentration (3.4 μg/L) to 

Maguayo 7 [Ref. 9, p. 304]. The PCE results for the Maguayo 2, Nevárez, and Santa Rosa wells are consistently 

below the MCL, ranging from approximately 1 μg/L to 2 μg/L in each of those wells [Ref. 9, pp. 303−304, 

306−308]. In general, the maximum reported PCE concentrations within the plume appear to have increased since 

2002 [Ref. 9, pp. 2−3, 301−308]. The maximum TCE concentrations within the plume appear to have decreased

[Ref. 9, pp. 1−3, 123−124, 301−308]. 

Maguayo System—The blended Maguayo system is composed of six ground water sources, wells Maguayo 2 

through Maguayo 7 [Ref. 10, pp. 1−4]. As of September 2015, Maguayo 2, Maguayo 6, and Maguayo 7 are active 

wells; Maguayo 3 and Maguayo 5 are inactive with the pumps intact and operable; and Maguayo 4 is inactive with 

the pump damaged or removed (the available documentation does not indicate the rationale for the inactivity) [Refs. 

6, pp. 7−12, 25−32; 7, p. 6]. Previous analytical results have indicated the presence of PCE and TCE in all the 

Maguayo wells [Refs. 9, pp. 2−3, 301−306; 26, p. 197]. 

Dorado Urbano System—The ground water component of the blended Dorado Urbano system is composed of the 

following wells: San Antonio 1, San Antonio 2, San Antonio 3, Higuillar, Dorado Dairy 1, Dorado Dairy 2, 

Nevárez, and Santa Rosa [Ref. 10, pp. 1−4]. As of September 2015, Nevárez and Santa Rosa are active; all other 

wells are inactive with the pumps removed [Refs. 6, pp. 6−10, 18−19, 21−24, 27, 37; 7, p. 6]. Previous analytical 

results have indicated the presence of PCE and TCE in all the Dorado Urbano wells [Ref. 9, pp. 123−124, 301−308]. 

In September 2015, EPA collected samples for VOC analysis from active and inactive wells in Dorado [Refs. 6, pp. 

3−13, 18−32, 37; 7, pp. 3−6, 10, 18−41]. The results confirm the continuing presence of VOCs in the wells, 

including MCL exceedances for PCE in one active and two inactive wells [Refs. 2, p. 4; 7, pp. 6, 10, 35−38; 8, pp. 

13−32; 51, pp. 3−4, 98, 112−113, 124−125, 138, 178, 188−189, 200−201, 212−213, 225, 236−237, 247−248]. The 

results for inactive wells at several locations surrounding the plume exhibit background levels, including non-detect 

results for all VOC parameters in the sample collected from the Vivoni well located south of the plume [Refs. 7, pp. 

6, 10, 33−34, 37−41; 8, pp. 3, 9−12, 33−36, 75, 84−85; 51, pp. 2, 4, 34−35, 48−49, 59−60, 259−260; 52, pp. 2, 

32−33]. Although possible sources of the VOCs in ground water have been identified, the contamination has not 

been shown to be attributable to any specific source or sources (see Section 3.1.1). 

9 
CL IENT NAME: DAT E:

PRO JECT :

T IT L E:

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@ A@

A@

A@

A@

WATER BOTTLING PLANT

DGWC-GW08 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 13 μg/L

Cis-1,2-DCE 1.1 μg/L

PCE 3.7 μg/L

TCE 0.32 J μg/L

M A G U A Y O 2 

D G W C -G W 0 6 (0 9 /2 3 /2 0 1 5 )

B ro m o di ch l o ro m e th a n e7 .9 μg /L

Ch lo ro fo rm 1 8 J+ (1 .8 ) μg/L

Cis-1 ,2 -D CE R

P CE 0 .6 6 J-μg/L

T CE R

HIGUILLAR 

DGWC-GW14 (09/28/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 0.50 U μg/L

Cis-1,2-DCE 0.50 U μg/L

PCE 0.50 U μg/L

TCE 0.12 J μg/L

VIVONI (background well)

DGWC-GW13 (09/25/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 0.50 U μg/L

Cis-1,2-DCE 0.50 U μg/L

PCE 0.50 U μg/L

TCE 0.50 U μg/L

MAGUAYO 5 

DGWC-GW12 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 18 μg/L

Cis-1,2-DCE 2.2 μg/L

PCE 11 μg/L

TCE 0.68 μg/L

SANTA ROSA

DGWC-GW11 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 1.9 μg/L

Cis-1,2-DCE 0.50 U μg/L

PCE 1.2 μg/L

TCE 0.50 U μg/L

MAGUAYO 3 

DGWC-GW10 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 24 μg/L

Cis-1,2-DCE 0.43 J μg/L

PCE 2.9 μg/L

TCE 0.17 J μg/L

MAGUAYO 4 

DGWC-GW09 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 13 μg/L

Cis-1,2-DCE 1.3 μg/L

PCE 7.6 μg/L

TCE 0.43 J μg/L

NEVAREZ 

DGWC-GW07 (09/24/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 0.50 U μg/L

Cis-1,2-DCE 0.50 U μg/L

PCE 1.5 μg/L

TCE 0.50 U μg/L

MAGUAYO 6 

DGWC-GW05 (09/23/2015)

Bromodichloromethane 0.16 J μg/L

Chloroform 11 μg/L

Cis-1,2-DCE 1.2 μg/L

PCE 5.0 μg/L

TCE 0.54 μg/L

MAGUAYO 7 

DGWC-GW04 (09/23/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 7.9 μg/L

Cis-1,2-DCE 1.0 μg/L

PCE 3.8 μg/L

TCE 0.50 μg/L

SAN ANTONIO 3 

DGWC-GW03 (09/23/2015)

Bromodichloromethane 0.50 U μg/L

Chloroform 0.50 U μg/L

Cis-1,2-DCE 0.50 U μg/L

PCE 0.50 U μg/L

TCE 0.91 μg/L

SAN ANTONIO 2

Bromodichloromethane 0.50 U / 0.50 U μg/L

Chloroform 0.50 U / 0.50 U μg/L

Cis-1,2-DCE 0.50 U / 0.50 U μg/L

PCE 0.23 J / 0.24 J μg/L

TCE 0.50 U / 0.50 U μg/L

DGWC-GW02/DGWC-GW19[duplicate] (09/22/2015) 

DORADO DAIRY 2 

DGWC-GW01 (09/22/2015)

Bromodichloromethane 0.50 U μg/L 

Chloroform 0.50 U μg/L 

Cis-1,2-DCE 0.50 U μg/L 

PCE 0.35 J μg/L 

TCE 0.15 J μg/L 

"

Site L oca tion

Puerto Rico

W O #:

®

R

W eston Solutions, Inc. 205 Ca m pus Drive Edison, New Jersey 08837-3939

T EL : (732) 417-5800 Fa x: (732) 417-5801

http://www.westonsolutions.com

EPA

Dora do Ground W a ter Conta m ina tion

CO NT RACT No.

EP-S8-13-01 Februa ry 2016 20408.012.004.0262.00

Site a nd Source

L oca tion Ma p

Figure #: 1

SO U RCES:

1. High Resolution O rthoim a gery. U nited Sta tes Geologica l Survey. 

 Acquisition Da te: O ctober 1, 2009. Acquired da ta : June 16, 2015. 

 http://ea rthexplorer.usgs.gov 

2. W eston Solutions, Inc. Region 8 ST ART IV, Region 2 Site 

 Assessm ent T ea m . Dora do GW Conta m ina tion, Site L ogbook

 W 0262.3B.00638, Septem ber 22-25 a nd 28, 2015.

3. References 6, pp. 5-13, 18-20; 7, pp. 4, 6, 10, 35-41;

 8, pp. 3, 9-36, 55-65, 84-85, 161; 10, p. 3; 28, pp. 7-8, 12.

3,000 1,500 0 3,000

Gra phic Sca le in Feet

L egend

μg/L m icrogra m s per liter

U T he a na lyte wa s not detected a t or a bove the a djusted Contra ct Required Qua ntita tion L im it for sa m ple a nd m ethod.

J T he a na lyte wa s positively identified a nd the a ssocia ted num erica l va lue is the a pproxim a te concentra tion.

J+ T he result is a n estim a ted qua ntity, but the result m a y be bia sed high.

J- T he result is a n estim a ted qua ntity, but the result m a y be bia sed low.

R T he result is unusa ble due to the qua lity of the da ta .

P:\SAT 2\SAT -Region8ST ART \Dora do GW HRS (0262)\MX D\17581_ Dora do_ W a ter_ Suppl_ W ell_ Plum e_ Ma p_ R1_ 8.5X 11.m xd

L egend

BLUE TEXT Background Level

RED TEXT Observed Release Concentration

BOLD RED TEXT Observed Release Concentration above HRS Benchmark

GREEN TEXT Detection of Contaminant of Concern (COC)

Results are presented as follows:

A@ W a ter Supply W ell Sa m ple L oca tion - Septem ber 2015

Area of O bserved Ground W a ter Conta m ina tion (Source 1)
CLIEN T N AME: DAT E: WO #:

PROJ ECT :

T IT LE:

!(

!(

!(

!(

!( !(

!(

!(

!( !(

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@ A@

A@

A@

A@

NARVAEZ CLEANERS 

AND TAILORING

Sam ple Date : March 2013

Soil

cis-1,2-DCE 6 μg/kg

Ground Water

N o Sa m ples Collected

Sub-slab Soil Vapor

1,1-DCE 176 μg/m 3

Chloroform 71.5 J μg/m 3

cis-1,2-DCE 455,000 J μg/m 3

PCE 3,510,000 J μg/m 3

T CE	 37,100 J μg/m 3

tra ns-1,2-DCE 2,090 J μg/m 3

V inyl chloride 5,240 J μg/m 3

Sam ple Date : Se pte m be r 2015

Sub-slab Soil Vapor

cis-1,2-DCE 49 μg/kg

PCE 750 μg/kg

tra ns-1,2-DCE 6.2 μg/kg

T CE 62 μg/kg

V inyl chloride 7.3 μg/kg

Ground Water

N o Sa m ples Collected

P RIDCO BUILDING NO: T-0320-0-56

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

COCs N ot Detected

EDWARD’S DRY 

CLEANERS TOA BAJA

Sam ple Date : Fe b 2015

Soil

Chloroform 7.1 μg/kg

Ground Water

COCs N ot Detected

P RIDCO BUILDING NO:S-0050-0-51

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

COCs N ot Detected

Hi Cla ss Clea ners

P RIDCO LOT NOS: L-107-2-64-16/18/19

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

COCs N ot Detected

P RIDCO BUILDING NO. T-1125-0-73 

AND T-1125-1-79

Sam ple Date : Fe b 2011

Soil

cis-1,2-DCE 21 μg/kg

PCE 1.7 J μg/kg

tra ns-1,2-DCE 1.7 J μg/kg

T CE 0.1J μg/kg

V inyl chloride 9.9 μg/kg

Ground Water

cis-1,2-DCE 3.2 J μg/L

tra ns-1,2-DCE 0.84 J μg/L

V inyl chloride 5.1 μg/L

P RIDCO BUILDINGS NO: S-1166-0-74 

AND S-1166-0-80

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

COCs N ot Detected

P RIDCO BUILDING NO. T-1322-0-88

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

1,1-DCE 2.6 J μg/L

P RIDCO BUILDINGS 

# T-0957-0-68/ 

T-0957-1-71/T-0957-2-72/

T-1053-0-73/T-1053-1-90

Sam ple Date : Fe b 2011

Soil

PCE 1.3 J μg/kg

T CE 1.5 J μg/kg

Ground Water

PCE 7.3 μg/L

T CE 1.6 J μg/L

P RIDCO BUILDING NOS: 

T-0868-0-67 AND T-0868-1-69

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

1,1-DCE 5 μg/L

cis-1,2-DCE 2.6 J μg/L

T CE 2.6 J μg/L 

FORMER NARVAEZ CLEANERS 

AND TAILORING FACILITY

Sam ple Date : March 2013

Soil

cis-1,2-DCE 0.74 J μg/kg

tra ns-1,2-DCE 2.1 J μg/kg

V inyl chloride 14 μg/kg

Ground Water

COCs N ot Detected

Biova il La bora tories

Interna tiona l SRL

Boston Scientific

P RIDCO BUILDING NO: S-0745-0-66

Sam ple Date : Fe b 2011

Soil

COCs N ot Detected

Ground Water

COCs N ot Detected

P RIDCO BUILDINGS NO:T-0638-0-66 

AND T-0638-1-67

Sam ple Date : Jan 2015

Soil

Chloroform 0.74 J μg/kg

Ground Water:

COCs N ot Detected

P RIDCO BUILDING NOS: S-0838-0-67 

AND T-0998-0-74

Sam ple Date : Fe b 2011

Soil

cis-1,2-DCE 1.6 J μg/kg

Ground Water

COCs N ot Detected

 P OZO SAN ANTONIO 2

 P OZO SAN ANTONIO 1

Depa rtm ent of Agriculture Dia gnostic La bora tory

 P OZO SAN ANTONIO 3

P OZO HIGUILLAR

HIGUILLAR DRY CLEANERS

Sam ple Date : Fe b 2015

Soil

Chloroform 10 μg/kg

cis-1,2-DCE 170 J μg/kg

PCE 44 μg/kg

tra ns-1,2-DCE 3.6 J μg/kg

T CE 73 μg/kg

V inyl chloride 150 μg/kg

Ground Water

cis-1,2-DCE 1,000 μg/L

PCE 380 μg/L

tra ns-1,2-DCE 17 μg/L

T CE 330 μg/L

V inyl chloride 380 μg/L

In-Ma r T ra ding

 P OZO MAGUAYO 6

 P OZO MAGUAYO 7

 P OZO MAGUAYO 2

 P OZO MAGUAYO 3

 P OZO MAGUAYO 4

 P OZO MAGUAYO 5

WAT ER BOT T LIN G PLAN T

USGS P IEZOMETER MAGUAYO 2

Sam ple Date : March 2013

 PCE 3.2 J μg/L 

P OZO DORADO DAIRY 2 

P OZO DORADO DAIRY 1 

 SANTA ROSA WELL

P OZO NEVAREZ

LAUNDRY ESP INOSA

Sam ple Date : Fe b 2015

Soil

Chloroform 3.8 μg/kg

PCE 0.90 J μg/kg

Ground Water

Chloroform 29 μg/L

Ma pei Ca ribe

Dora do Electropla ting

Gulbra ndsen Puerto Rico Inc.

Prism a Print El V iejo Meta l Recycling

METAL MACHINING CO., INC

Sam ple Date : March 2013

Soil

COCs N ot Detected

Ground Water

N o Sa m ples Collected

ADRIEL AUTO 

Sam ple Date : March 2013

Soil

cis-1,2-DCE 1.2 J μg/kg

Ground Water

cis-1,2-DCE 1.1 J μg/L

*Petroleum product observed a t wa ter ta ble

P OZO VIVONI

GREEN P OINT SIGN AND 

SCREEN P RINTING

Sam ple Date : March 2013

Soil

COCs N ot Detected

Ground Water

N o Sa m ples Collected

®

R

Weston Solutions, Inc. 205 Ca m pus Drive Edison, N ew J ersey 08837-3939

T EL: (732) 417-5800 Fa x: (732) 417-5801

http://www.westonsolutions.com

EPA

Dora do Ground Wa ter Conta m ina tion

CON T RACT No.

EP-S8-13-01 Februa ry 2016 20408.012.004.0262.00

Loca tions of Other 

Possible Sources 

4,000 2,000 0 4,000

Gra phic Sca le in Feet

Docum ent Pa th: P:\SAT 2\SAT -Region8ST ART \Dora do GW HRS (0262)\MX D\17580_ Ma gua yo_ Study_ Area _ rev21016_ 8.5X 11.m xd

Figure #: 2

Le g e nd

A@ Active Public Supply Well

A@ Active Com m ercia l Supply Well

A@ Ina ctive Public Supply Well - Pum p Inta ct

A@ Ina ctive Public Supply Well - Pum p Rem oved

A@ U SGS Monitoring Well Loca tion

Area of Observed Ground Wa ter Conta m ina tion (Source 1)

Detection of Conta m ina nt of Concern (COC) rela ted to 

Regiona l Ground Wa ter Conta m ina tion.

1.3 ug/L

!( Other Possible Source Fa cility (N ot Sa m pled by EPA)

Possible Source Fa cility Sa m pled by EPA (2011, 2013, 2015). 

N OT ES:

1. Only the m a xim um detected va lue per sa m ple m a trix a t ea ch site shown on this figure

2. All ground wa ter results a re in m icrogra m s per liter (ug/l). 

3. All V OC soil results a re in m icrogra m s per kilogra m (ug/kg).

4. All sub-sla b soil va por sa m ples a re in m icrogra m s per cubic m eter (ug/m 3).

5. V OC - V ola tile orga nic com pounds

6. PCE - T etra choloroethene

7. T CE - T richloroethene

8. J – Estim a ted V a lue

9. COC - Conta m ina nt of Concern

SOU RCES:

1. U nited Sta tes Arm y Corps of Engineers, 8-bit T rue Color Im a ges of Puerto Rico, 2004.

2. References 6, pp. 5-20; 7, pp. 4, 10; 29, pp. 11-26, 33; a nd References 30 through 50.
SD-Characterization

Source No.: 1

2.2 SOURCE CHARACTERIZATION

Number of the source: 1 

Source Type of the source: Other

Name and description of the source: Ground Water Plume – Dorado, Puerto Rico

Source 1 is considered a contaminated ground water plume of unknown volume without an identified source. 

Results reported by USGS, PRDOH, PRASA, and the Puerto Rico Environmental Quality Board (PREQB) since the 

1980s for PRASA-operated wells in the Dorado area have indicated the constant presence of PCE and TCE in 

Dorado area wells [Refs. 9, all pages; 23, p. 2; 26, p. 4; 27, pp. 8−23]. EPA collected ground water samples from 

public supply wells and a well at a water bottling plant (see note below) in September 2015 [Refs. 6, pp. 4−13, 19; 

7, pp. 3−6]. Analytical results indicated the presence of bromodichloromethane, chloroform, cis-1,2-DCE PCE, and 

TCE in the samples, at concentrations significantly above the background levels in the upgradient Vivoni well and 

other wells exhibiting background concentrations (see Section 2.4.1). The PCE concentrations in three wells 

(Maguayo 4, Maguayo 5, and Maguayo 6) exceed the EPA MCL of 5 μg/L [Refs. 2, p. 4; 7, pp. 6, 35−38; 8, pp. 

1−8, 58, 61, 64; 51, pp. 3−4, 125, 201, 248]. The Maguayo 6 well is currently active and contributing to the blended 

Maguayo water supply system; Maguayo 4 and Maguayo 5 are currently inactive but are still considered as viable 

components of the system [Refs. 7, pp. 6, 22, 26, 29; 10, pp. 35, 38, 40]. Other active wells that exhibit observed 

release concentrations include Maguayo 2, Maguayo 7, Nevárez, and Santa Rosa [Refs. 7, p. 6; 8, pp. 1−8, 57, 

59−60, 63−64; 51, pp. 3−4, 112−113, 138, 178, 236−237].

In July 2015, EPA conducted a reconnaissance of the Maguayo and Dorado Urbano well systems to determine their 

condition and accessibility for sampling [Ref. 5, pp. 1−36]. During the reconnaissance and the follow-up sampling 

in September 2015, the following wells were observed to be active: Santa Rosa, Nevárez, Maguayo 2, Maguayo 6, 

and Maguayo 7 [Refs. 5, pp. 26−27, 35−36; 6, pp. 7−12; 7, p. 6]. Some of the wells, including Maguayo 3 and 

Maguayo 5, are inactive but have intact infrastructure (i.e., pump and electrical connections) [Refs. 6, pp. 9−12, 

29−32; 7, pp. 27, 29]. The remaining wells are in various states of disrepair, ranging from disconnected electrical 

power, to missing a pump, to consisting of only an open well casing [Refs. 5, pp. 2−15, 29−30; 6, pp. 3−13, 21−32; 

7, pp. 18−31]. Although PRASA has discontinued the use of some wells, periodic drought conditions necessitate 

further use of some contaminated wells [Refs. 21, p. 11; 26, p. 3−4; 29, pp. 3, 6]. During the sampling event, the 

Santa Rosa well was being used to fill water supply tanker trucks [Ref. 6, p. 7]. The populations served and duration 

of emergency service is unknown, so it is unclear what populations meet the definition of regularly using the water; 

therefore, the emergency service is not considered in population apportionment for scoring the site [Ref. 1, p. 

51603]. 

Note: The water bottling plant withdraws water from a well that is 300 feet deep; prior to bottling and distribution, 

the water is purified using several treatment methods, including multimedia filters, activated carbon, water softeners, 

reverse osmosis (RO), ultraviolet rays, micro filtration, and recirculated ozone [Refs. 5, p. 34; 10, pp. 92, 96−97].

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

The ground water plume is identified by contamination found in the following water supply wells [Refs. 6, pp. 

7−13; 7, pp. 6, 20−30; 8, pp. 1−8, 56−64; 51, pp. 3−4, 98, 112−113, 124−125, 138, 178, 188−189, 200−201, 

212−213, 225, 236−237, 247−248]: 

• Active wells: Maguayo 2, Maguayo 6, Maguayo 7, Nevárez, Santa Rosa, water bottling plant

• Inactive wells (pump intact): Maguayo 3, Maguayo 5 

• Inactive wells (pump inoperable or removed): Maguayo 4, San Antonio 3

For the purpose of this report, these wells represent a minimum of the plume extent. The site is located in 

northeastern Puerto Rico and is shown in Figure 1. 

12
SD-Containment

Source No.: 1

Containment

Release to ground water:

Based on evidence of hazardous substance migration (i.e., detections significantly above background in ground 

water samples from the Maguayo 2, Maguayo 3, Maguayo 4, Maguayo 5, Maguayo 6, Maguayo 7, Nevárez, Santa 

Rosa, Dorado Ice & Water, and San Antonio 3 wells) and due to the fact that there is nothing to prevent the plume 

from migrating further, a containment factor of 10 is assigned [Refs. 1, p. 51596; 7, pp. 6, 35−38; 8, pp. 1−3, 56−64; 

51, pp. 2−4, 34−35, 48−49, 59−60, 98, 112−113, 124−125, 138, 178, 188−189, 200−201, 212−213, 225, 236−237, 

247−248, 259−260; 52, pp. 2, 32−33].

13
SD- Hazardous Substances

Source No.: 1

2.4.1 Hazardous Substances

Ground water samples collected by EPA in 2015 showed the presence of volatile organic compounds (VOC) at 

observed release concentrations (i.e., significantly above background levels) in Dorado area supply wells, as 

described below and discussed in more detail in Section 3.1.1. 

EPA Sampling Event – Ground Water Samples: September 2015

In September 2015, EPA collected ground water samples from five active water supply wells and eight inactive 

water supply wells owned by PRASA and from one commercial production well operated by a water bottling plant

[Refs. 6, pp. 3−13, 18−32, 37; 7, pp. 3−6, 10, 18−31]. All samples consisted of raw water collected prior to any onsite treatment [Ref. 7, pp. 3−6]. The water bottling plant did not have a sampling spigot prior to its 2,000-gallon 

holding tank; therefore, the sample from that well (DGWC-GW08) was collected after passing through the storage 

tank, which has continuous flow-through [Refs. 6, p. 11; 7, pp. 4, 25]. The ground water samples were analyzed for 

Organic Target Analyte List (TAL) VOCs (trace concentration) according to EPA Contract Laboratory Program 

[CLP] Statement of Work for Organic Superfund Methods, Multi-Media, Multi-Concentration, SOM02.2, under

CLP Case No. 45651 [Refs. 8, pp. 1−4; 51, pp. 16−18; 52, pp. 13−15]. The quantitation limit reported for each 

result was the contract-required quantitation limit (CRQL) adjusted for sample and method [Ref. 8, pp. 3, 75]. Since 

the samples were analyzed through CLP, these adjusted CRQLs are used in place of the HRS-defined sample 

quantitation limit (SQL) [Ref. 1, Sections 1.1 and 2.3]. Chain-of-custody was maintained for the samples 

throughout collection, shipping, and analysis [Refs. 7, pp. 33−39, 41; 8, pp. 4−8; 51, pp. 2−4; 52, p. 2].

Bromodichloromethane, chloroform, cis-1,2-DCE, PCE, and TCE were each detected above the applicable CRQL 

(0.50 μg/L, adjusted for sample characteristics when necessary) in at least one ground water sample; individual 

concentrations ranged from 0.50 μg/L to 24 μg/L [Refs. 1, p. 51585−51586, 51589; 8, pp. 3, 56−64; 51, pp. 3−4, 98, 

112−113, 124−125, 138, 178, 188−189, 200−201, 212−213, 225, 236−237, 247−248]. Wells at several locations 

surrounding the plume exhibited background concentrations for site-specific hazardous substances, including nondetect results for all five substances in the sample collected from the Vivoni well to the south [Refs. 7, pp. 6, 10; 8, 

pp. 3, 55−56, 64−65, 75, 161; 51, pp. 2, 4, 34−35, 48−49, 59−60, 259−260; 52, pp. 2, 32−33]. Additional 

information regarding background levels is presented in Section 3.1.1. 

TABLE 1. SOURCE 1 HAZARDOUS SUBSTANCES

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

CRQL 

(μg/L)

Reference

Bromodichloromethane DGWC-GW06/BCJQ6 09/23/2015 7.9 0.50 7, pp. 6, 23, 35; 8, pp. 

4−8, 19, 59; 51, pp. 3, 138

2, 

DGWC-GW01/BCJQ1* 09/22/2015 U* 0.50 7, pp. 6, 18, 33; 8, pp. 

55; 51, pp. 2, 35

2−9, 

DGWC-GW02/BCJQ2* 09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

11, 56; 51, pp. 2, 49

2−8, 

DGWC-GW19/BCJR9*

(DUP of DGWC-GW02)

09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

35, 65; 51, pp. 2, 60

2−8, 

DGWC-GW13/BCJR3* 09/25/2015 U* 0.50 7, pp. 6, 30, 37; 8, pp. 

33, 64; 51, pp. 4, 260

2−8, 

DGWC-GW14/BCJR4* 09/28/2015 U* 0.50 7, pp. 6, 31, 39; 8, pp. 

74−84, 161; 52, pp. 2, 33

Chloroform DGWC-GW04/BCJQ4 09/23/2015 7.9 0.50 7, pp. 6, 21, 35; 8, pp. 

4−8, 15, 57; 51, pp. 3, 112

2, 

DGWC-GW05/BCJQ5 09/23/2015 11 0.50 7, pp. 6, 22, 35; 8, 

4−8, 17, 58; 51, pp. 3, 

pp. 

124

2, 

DGWC-GW08/BCJQ8 09/24/2015 13 0.50 7, pp. 6, 25, 37; 8, pp. 

4−8, 23, 60; 51, pp. 4, 188

2, 

Chloroform DGWC-GW09/BCJQ9 09/24/2015 13 0.50 7, pp. 6, 26, 37; 8, pp. 2, 

14
TABLE 1. SOURCE 1 HAZARDOUS SUBSTANCES

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

CRQL 

(μg/L)

Reference

(continued) 4−8, 25, 61; 51, pp. 4, 200

DGWC-GW10/BCJR0 09/24/2015 24 2.5 7, pp. 6, 27, 37; 8, 

4−8, 27, 62; 51, pp. 

225

pp. 2, 

4, 212, 

DGWC-GW11/BCJR1 09/24/2015 1.9 0.50 7, pp. 6, 28, 37; 8, pp. 

4−8, 29, 63; 51, pp. 4, 236

2, 

DGWC-GW12/BCJR2 09/24/2015 18 0.50 7, pp. 6, 29, 37; 8, pp. 

4−8, 31, 63; 51, pp. 4, 247

2, 

DGWC-GW01/BCJQ1* 09/22/2015 U* 0.50 7, pp. 6, 18, 33; 8, pp. 

55; 51, pp. 2, 34

2−9, 

DGWC-GW02/BCJQ2* 09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

11, 56; 51, pp. 2, 48

2−8, 

DGWC-GW19/BCJR9*

(DUP of DGWC-GW02)

09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

35, 65; 51, pp. 2, 59

2−8, 

DGWC-GW13/BCJR3* 09/25/2015 U* 0.50 7, pp. 6, 30, 37; 8, pp. 

33, 64; 51, pp. 4, 259

2−8, 

DGWC-GW14/BCJR4* 09/28/2015 U* 0.50 7, pp. 6, 31, 39; 8, pp. 

74−84, 161; 52, pp. 2, 32

cis-1,2-DCE DGWC-GW04/BCJQ4 09/23/2015 1.0 0.50 7, pp. 6, 21, 35; 8, pp. 

4−8, 15, 57; 51, pp. 3, 112

2, 

DGWC-GW05/BCJQ5 09/23/2015 1.2 0.50 7, pp. 6, 22, 35; 8, pp. 

4−8, 17, 58; 51, pp. 3, 124

2, 

DGWC-GW08/BCJQ8 09/24/2015 1.1 0.50 7, pp. 6, 25, 37; 8, pp. 

4−8, 23, 60; 51, pp. 4, 188

2, 

DGWC-GW09/BCJQ9 09/24/2015 1.3 0.50 7, pp. 6, 26, 37; 8, pp. 

4−8, 25, 61; 51, pp. 4, 200

2, 

DGWC-GW12/BCJR2 09/24/2015 2.2 0.50 7, pp. 6, 29, 37; 8, pp. 

4−8, 31, 63; 51, pp. 4, 247

2, 

DGWC-GW01/BCJQ1* 09/22/2015 U* 0.50 7, pp. 6, 18, 33; 8, pp. 

55; 51, pp. 2, 34

2−9, 

DGWC-GW02/BCJQ2* 09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

11, 56; 51, pp. 2, 48

2−8, 

DGWC-GW19/BCJR9*

(DUP of DGWC-GW02)

09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

35, 65; 51, pp. 2, 59

2−8, 

DGWC-GW13/BCJR3* 09/25/2015 U* 0.50 7, pp. 6, 30, 37; 8, pp. 

33, 64; 51, pp. 4, 259

2−8, 

DGWC-GW14/BCJR4* 09/28/2015 UJ* 0.50 7, pp. 6, 31, 39; 8, pp. 

74−84, 161; 52, pp. 2, 32

PCE DGWC-GW04/BCJQ4 09/23/2015 3.8 0.50 7, pp. 6, 21, 35; 8, pp. 

4−8, 16, 57; 51, pp. 3, 113

2, 

DGWC-GW05/BCJQ5 09/23/2015 5.0 0.50 7, pp. 6, 22, 35; 8, pp. 

4−8, 18, 58; 51, pp. 3, 125

2, 

DGWC-GW06/BCJQ6 09/23/2015 0.66 J- 0.50 7, pp. 6, 23, 35; 8, pp. 2−8, 

20, 59; 51, pp. 3, 138

DGWC-GW07/BCJQ7 09/24/2015 1.5 0.50 7, pp. 6, 24, 37; 8, pp. 

4−8, 22, 60; 51, pp. 4, 178

2, 

DGWC-GW08/BCJQ8 09/24/2015 3.7 0.50 7, pp. 6, 25, 37; 8, pp. 

4−8, 24, 60; 51, pp. 4, 189

2, 

DGWC-GW09/BCJQ9 09/24/2015 7.6 0.50 7, pp. 6, 26, 37; 8, pp. 

4−8, 26, 61; 51, pp. 4, 201

2, 

PCE (continued) DGWC-GW10/BCJR0 09/24/2015 2.9 0.50 7, pp. 6, 27, 37; 8, pp. 

4−8, 28, 62; 51, pp. 4, 213

2, 

15
TABLE 1. SOURCE 1 HAZARDOUS SUBSTANCES

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

CRQL 

(μg/L)

Reference

DGWC-GW11/BCJR1 09/24/2015 1.2 0.50 7, pp. 6, 28, 37; 8, pp. 

4−8, 30, 63; 51, pp. 4, 237

2, 

DGWC-GW12/BCJR2 09/24/2015 11 0.50 7, pp. 6, 29, 37; 8, pp. 

4−8, 32, 64; 51, pp. 4, 248

2, 

DGWC-GW01/BCJQ1* 09/22/2015 0.35J* 0.50 7, pp. 6, 18, 33; 8, pp. 

55; 51, pp. 2, 35

2−9, 

DGWC-GW02/BCJQ2* 09/22/2015 0.23J* 0.50 7, pp. 6, 19, 33; 8, pp. 

11, 56; 51, pp. 2, 49

2−8, 

DGWC-GW19/BCJR9*

(DUP of DGWC-GW02)

09/22/2015 0.24J* 0.50 7, pp. 6, 19, 33; 8, pp. 

35, 65; 51, pp. 2, 60

2−8, 

DGWC-GW13/BCJR3* 09/25/2015 U* 0.50 7, pp. 6, 30, 37; 8, pp. 

33, 64; 51, pp. 4, 260

2−8, 

DGWC-GW14/BCJR4* 09/28/2015 U* 0.50 7, pp. 6, 31, 39; 8, pp. 

74−85, 161; 52, pp. 2, 33

TCE DGWC-GW03/BCJQ3 09/23/2015 0.91 0.50 7, pp. 6, 20, 35; 8, pp. 

4−8, 13, 56; 51, pp. 3, 98

2, 

DGWC-GW04/BCJQ4 09/23/2015 0.50 0.50 7, pp. 6, 21, 35; 8, pp. 

4−8, 15, 57; 51, pp. 3, 112

2, 

DGWC-GW05/BCJQ5 09/23/2015 0.54 0.50 7, pp. 6, 22, 35; 8, pp. 

4−8, 17, 58; 51, pp. 3, 124

2, 

DGWC-GW12/BCJR2 09/24/2015 0.68 0.50 7, pp. 6, 29, 37; 8, pp. 

4−8, 31, 63; 51, pp. 4, 247

2, 

DGWC-GW01/BCJQ1* 09/22/2015 0.15J* 0.50 7, pp. 6, 18, 33; 8, pp. 

55; 51, pp. 2, 34

2−9, 

DGWC-GW02/BCJQ2* 09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

11, 56; 51, pp. 2, 48

2−8, 

DGWC-GW19/BCJR9*

(DUP of DGWC-GW02)

09/22/2015 U* 0.50 7, pp. 6, 19, 33; 8, pp. 

35, 65; 51, pp. 2, 59

2−8, 

DGWC-GW13/BCJR3* 09/25/2015 U* 0.50 7, pp. 6, 30, 37; 8, pp. 

33, 64; 51, pp. 4, 259

2−8, 

DGWC-GW14/BCJR4* 09/28/2015 0.12J* 0.50 7, pp. 6, 31, 39; 8, pp. 

74−84, 161; 52, pp. 2, 32

μg/L micrograms per liter

CRQL Contract-required quantitation limit, adjusted for sample and method [Ref. 8, pp. 3, 75] 

U The analyte was analyzed for, but was not detected at a level greater than or equal to the level of the 

adjusted CRQL for sample and method [Ref. 8, pp. 3, 75].

 * Results are representative of background levels (see Section 3.1.1) 

J The analyte was positively identified and the associated numerical value is the approximate concentration 

of the analyte in the sample (due either to the quality of the data generated because certain quality control 

criteria were not met, or the concentration of the analyte was below the CRQL) [Refs. 8, pp. 3, 75; 28, pp. 

4−8].

J- The result is an estimated quantity that might be biased low [Ref. 8, p. 3]. In accordance with the 

November 1996 EPA fact sheet Using Qualified Data to Document an Observed Release and Observed 

Contamination, the value is usable without adjustment [Ref. 28, pp. 4−8].

DUP Duplicate ground water sample.

16
SD-Hazardous Waste Quantity

Source No.: 1

2.4.2 Hazardous Waste Quantity

2.4.2.1.1 Hazardous Constituent Quantity (Tier A)

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 CERCLA hazardous substances in the source and releases from the 

source is not known and cannot be estimated with reasonable confidence [Ref. 1, pp. 51590-51591 (Section 

2.4.2.1.1)]. Insufficient historical and current data [manifests, potentially responsible party (PRP) records, State 

records, permits, waste concentration data, etc.] are available to adequately calculate the total mass, or a partial 

estimate, of all CERCLA hazardous substances in the source and the associated releases from the source. Therefore, 

there is insufficient information to calculate a total or partial Hazardous Constituent Quantity estimate for Source 

No. 1 with reasonable confidence. Scoring proceeds to the evaluation of Tier B, Hazardous wastestream quantity 

[Ref. 1, p. 51591]. 

Hazardous Constituent Quantity (C) Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity (Tier B) 

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

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

pollutants and contaminants for the source and releases from the source is not known and cannot be estimated with 

reasonable confidence [Ref. 1, p. 51591 (Section 2.4.2.1.2)]. Insufficient historical and current data (manifests, PRP 

records, State records, permits, waste concentration data, annual reports, etc.) are available to adequately calculate 

the total mass, or a partial estimate, of all hazardous wastestreams and CERCLA pollutants and contaminants for the 

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

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

confidence. Scoring proceeds to the evaluation of Tier C, Volume [Ref. 1, p. 51591]. 

Hazardous Wastestream Quantity (W) Value: NS

2.4.2.1.3 Volume (Tier C)

Because there are wells with samples showing contamination in the ground water but the volume of the 

contaminated area has not been determined, the volume of the ground water contamination is considered to be 

greater than 0 cubic yards but unknown [Figure 1; Refs. 7, pp. 6, 10, 35−38; 8, pp. 13−34, 56−65; 51, pp. 3−4, 98, 

112−113, 124−125, 138, 178, 188−189, 200−201, 212−213, 225, 236−237, 247−248]. The source type is “Other,” 

so the volume value is divided by 2.5 to obtain the assigned value, as shown below [Ref. 1, p. 51591, Section 

2.4.2.1.3, Table 2-5].

Dimension of source (yd3

): >0 yd3

Volume (V) Assigned Value: (>0)/2.5 = >0

2.4.2.1.4 Area (Tier D)

Tier D is not evaluated for source type “other” [Ref. 1, p. 51591, Table 2-5, Section 2.4.2.1.4].

Area of source (ft2

): N/A

Area (A) Assigned Value: 0

2.4.2.1.5 Source Hazardous Waste Quantity Value

The source hazardous waste quantity value for Source 1 is >0 for Tier C - Volume [Ref. 1, p. 51591].

Source Hazardous Waste Quantity Value: >0

17
SD-Summary

SITE SUMMARY OF SOURCE DESCRIPTIONS

TABLE 2. HAZARDOUS WASTE QUANTITY AND CONTAINMENT

Source Number Source Hazardous 

Waste Quantity 

Value

Containment

Ground Water Surface 

Water

Air (Gas) Air 

(Particulate)

1 >0 10 NS NS NS

NS = Not Scored

18
GW-General

3.0 GROUND WATER MIGRATION PATHWAY

Note: Reference 19 and 20 are complete copies of published USGS reports. Original USGS pagination is used 

when citing these two references.

3.0.1 General Considerations

The aquifer being evaluated at the Dorado Ground Water Contamination site is the upper aquifer of the North Coast 

Limestone Aquifer System (NCLAS) (hereinafter, “NCLAS upper aquifer” or “aquifer”), which is the principal 

source of fresh ground water in Dorado and historically has been the principal source of public-supply and industrial 

water use in the region [Refs. 19, pp. 1−5; 20, pp. 1−7; 21, pp. 11−18]. The water supply wells sampled by EPA in 

September 2015 range in depth from 105 to 350 feet below ground surface (ft bgs) and have screened intervals in

the formations that compose the NCLAS upper aquifer [Ref. 10, pp. 1−27, 47−53, 85]. Only the wells that were 

sampled are considered for scoring, but the NCLAS upper aquifer underlies an area of approximately 430 square 

miles in northern Puerto Rico, including the site and surroundings; the aquifer’s most productive area includes 

Dorado [Ref. 19, pp. 4−5].

The NCLAS consists of a sequence of limestone formations that dip northward toward the Atlantic Ocean [Refs. 19, 

p. 9; 20, p. 3]. In the Dorado area, the NCLAS upper aquifer is composed of (in descending order) the permeable 

parts of surficial unconsolidated deposits, the Aymamón Limestone, the Aguada Limestone, and the upper 

permeable parts of the Cibao formation (including all its members) [Refs. 4, p. 1; 10, p. 47; 20, p. 11; 22, pp. 

51−52]. These formations are in hydraulic connection in the Dorado area and are classified as a single 

hydrogeologic unit [Refs. 19, pp. 4−5; 20, p. 11]. Current and former drinking water wells within and surrounding 

the ground water plume (i.e., Source 1) are finished in all three rock formations, including at least three wells that 

are reported to be finished in both the Aguada Limestone and Cibao Formation [Ref. 10, pp. 3−27, 30, 50−52, 

62−63, 77−82, 85].

The NCLAS upper aquifer is overlain by unsaturated portions of the surficial unconsolidated deposits and limestone 

formations, which contribute varying levels of recharge to the underlying aquifer [Refs. 19, pp. 4, 6, 8; 20, pp. 1, 7, 

10−11, 13, 18, 25−27; 22, p. 65]. Ground water exists under unconfined conditions within the aquifer, with the 

water table (i.e., the top of the aquifer) situated at elevations of approximately 1 to 10 feet above mean sea level 

(MSL) [Refs. 10, pp. 3−4; 20, pp. 7, 12−13, 25, 27; 22, pp. 8, 51−52]. Depth to ground water at the site is 15.4 to 

118 feet below ground surface (bgs) [Refs. 7, pp. 18−20, 26, 31; 10, pp. 3−4]. Ground water generally flows in a 

northerly direction toward the coast, with a smaller ground water flow component east toward the north-flowing Río 

de la Plata [Refs. 21, p. 18; 22, p. 52]. Karstification, seasonal fluctuations, drought conditions, ground water 

withdrawals, and development can create drawdown that affects the direction of ground water flow in the aquifer 

locally [Refs. 21, p. 18; 22, pp. 51−56]. Although the relatively impermeable part of the Cibao Formation generally 

forms the lower boundary of the aquifer, which limits vertical ground water flow, the freshwater−saltwater interface 

forms the aquifer’s effective lower boundary at and north of the site [Ref. 20, pp. 7, 11, 18, 25]. The freshwater lens 

in the NCLAS upper aquifer is estimated to be 200 to 300 feet thick at and in the vicinity of the site [Ref. 19, p. 12]. 

The Dorado region is characterized by karst topography, specifically, outcrops of the Aymamón Limestone known 

as mogotes. The mogotes commonly contain large holes at their bases, acting as channels that capture surface 

runoff and recharge the underlying limestone [Refs. 20, pp. 3, 10, 13; 21, pp. 11−15; 22, pp. 8−12, 31, 36, 51−52, 

63]. The limestone units that make up the water-table aquifer exhibit typical karst characteristics, such as 

transmission of ground water through channel networks near the water table, decreasing permeability with 

increasing depth below the water table, zones of exceptionally high permeability in valleys, and a permeable and 

cavernous unsaturated zone [Refs. 20, pp. 3, 10, 13; 21, pp. 11−15; 22, pp. 8−12, 31, 36, 51−52, 63]. Hydraulic 

conductivity of the NCLAS upper aquifer is estimated to range from less than 1 meter per day (m/d; converts to 1.15

x 10-3 centimeters per second [cm/s]*) to more than 2,000 m/d (2.3 cm/s); the parts of the aquifer with hydraulic 

conductivities less than 30 m/d (3.45 x 10-2 cm/s) are considered the least permeable [Ref. 22, p. 61].

* Conversion: (1 m/d) x (100 cm/m) x (1/86,400 d/s) = 1.15 x 10-3 cm/s

19
GW-General

Stratum 1 (shallowest)

Stratum/Aquifer Name: NCLAS upper aquifer

Description: 

In the Dorado area, the NCLAS upper aquifer is composed of the permeable parts of surficial unconsolidated 

deposits, the Aymamón Limestone, the Aguada Limestone, and the upper permeable parts of the Cibao Formation

[Refs. 4, p. 1; 10, p. 47; 20, p. 11; 22, pp. 51−52]. These formations are in hydraulic connection in the area and are 

classified as a single hydrogeologic unit (i.e., the upper aquifer) [Refs. 19, pp. 4−5; 20, p. 11]. The unconsolidated 

deposits consist mainly of quartz sand and reddish-brown clay referred to collectively as blanket sands; the average 

thickness of these deposits is 4 to 10 meters (approximately 13 to 33 feet) [Ref. 20, p. 6]. There are also a variety of 

unconsolidated and semi-consolidated deposits adjacent to rivers and near the coast, including river-terrace deposits, 

deltaic and mud-flat deposits, beach deposits, eolianites, landslide debris, alluvium, swamp deposits, beach deposits, 

and reef deposits [Ref. 20, p. 6].

The Aymamón Limestone is thick-bedded to massive, very pure limestone; it is dolomitic near the coast and its 

thickness ranges from 190 to 330 meters (approximately 620 to 1,100 feet) [Refs. 21, p. 15; 22, pp. 30−31]. The 

Aguada Limestone consists of hard calcarenite alternating with chalky and rubbly limestone; the formation ranges in 

thickness from 60 to 175 meters (approximately 200 to 575 feet), and in many places the limestone is sandy [Refs.

21, p. 15; 22, p. 30]. In the area east of the Río Cibuco, which includes the location of Source 1 and surroundings, 

the Aguada Limestone is saturated and is in hydraulic connection with the underlying Cibao Formation and older 

carbonate units [Ref. 19 pp. 4−5]. The upper part of the Cibao Formation consists of beds of calcareous clay, earthy 

limestone, and marl indicative of its four members present in the Dorado region (i.e., upper member, Miranda Sand 

Member, Quebrada Arenas Limestone Member, and Río Indio Limestone Member) [Refs. 20, pp. 4−5; 21, pp. 

14−15]. The thickness of the Cibao Formation ranges from 50 to 200 meters (approximately 160 to 660 feet); the 

relatively impermeable part of the formation forms the lower boundary of the upper aquifer [Ref. 20, pp. 4, 11]. 

20
GW-Observed Release

3.1 LIKELIHOOD OF RELEASE

3.1.1 Observed Release

Aquifer Being Evaluated: NCLAS – upper aquifer

Multiple observed releases are documented for the Dorado Ground Water Contamination site. Chemical analyses 

for ground water samples collected from the active and inactive supply wells in September 2015 confirm the 

presence of hazardous substances in the aquifer [see “Chemical Analysis”, below]. 

Direct Observation

The aquifer is not evaluated for observed release by direct observation.

Chemical Analysis

In September 2015, EPA collected ground water samples from five active water supply wells and eight inactive 

water supply wells owned by PRASA and from one commercial production well operated by a water bottling plant

[Refs. 6, pp. 3−13, 18−32, 37; 7, pp. 3−6, 10, 18−31]. All samples consisted of raw water collected prior to any onsite treatment [Ref. 7, pp. 3−6]. The water bottling plant did not have a sampling spigot prior to its 2,000-gallon 

holding tank; therefore, the sample from that well (DGWC-GW08) was collected after passing through the storage 

tank, which has continuous flow-through [Ref. 7, pp. 4, 25]. The ground water samples were analyzed for Organic 

TAL VOCs (trace concentration) according to “EPA Contract Laboratory Program [CLP] Statement of Work for 

Organic Superfund Methods, Multi-Media, Multi-Concentration, SOM02.2”, under CLP Case No. 45651 [Refs. 8, 

pp. 1−4, 74–79; 51, pp. 1–18; 52, pp. 1–15]. The quantitation limit reported for each result was the CRQL adjusted 

for sample and method [Ref. 8, pp. 3, 75]. Since the samples were analyzed through CLP, these adjusted CRQLs 

are used in place of the HRS-defined SQL [Ref. 1, Sections 1.1 and 2.3]. Chain-of-custody was maintained for the 

samples throughout collection, shipping, and analysis [Refs. 7, pp. 33−39, 41; 8, pp. 4−8; 51, pp. 2−4; 52, p. 2].

At each active well and inactive well with a functioning pump, Region 2 SAT collected raw ground water samples 

(i.e., prior to water treatment) from sampling spigots as close as possible to the wellhead; the well at the water 

bottling plant was sampled from a spigot after a water tank but before treatment [Refs. 6, pp. 8−13; 7, p. 4]. For 

those wells where electrical service has been disconnected, Region 2 SAT procured an electrical subcontractor to 

restore power to the pump [Refs. 6, pp. 10−12; 7, p. 4]. At each inactive well without a functioning pump, Region 2 

SAT collected samples using ground water purging and sampling techniques, and included measuring the depth to 

ground water at each well. All wells with the exception of the water bottling plant were purged prior to sample 

collection, and water quality parameters (i.e., pH, specific conductance, temperature, and turbidity) were recorded

[Refs. 6, pp. 5−8, 11−13; 7, pp. 4, 18−30]. For Quality Assurance/Quality Control (QA/QC) purposes, Region 2 

SAT collected one environmental duplicate ground water sample, four trip blank samples to evaluate crosscontamination, and three rinsate blank samples to demonstrate adequate decontamination of the submersible pump 

[Refs. 6, pp. 6, 8, 9, 11, 19; 7, pp. 4, 6].

Bromodichloromethane, chloroform, cis-1,2-DCE, PCE, and TCE were each detected above the applicable CRQL 

(0.50 μg/L, adjusted for sample characteristics when necessary) in at least one ground water sample; individual 

concentrations ranged from 0.50 μg/L to 24 μg/L [Refs. 1, p. 51585−51586, 51589; 8, pp. 3, 56−64; 51, pp. 3−4, 98, 

112−113, 124−125, 138, 178, 188−189, 200−201, 212−213, 225, 236−237, 247−248]. Wells at several locations 

surrounding the plume exhibited background concentrations for site-specific hazardous substances, including nondetect results for all five substances in the sample collected from the Vivoni well to the south [Refs. 7, pp. 6, 10; 8, 

pp. 3, 55−56, 64−65, 75, 161; 51, pp. 2, 4, 34−35, 48−49, 59−60, 259−260; 52, pp. 2, 32−33].

Notes about background conditions and sample similarity: 

The chlorinated solvents found in the public supply wells are not naturally occurring [Refs. 11, p. 1; 13, p. 1]. PCE 

and TCE are man-made chlorinated solvents that are commonly used in commercial/industrial operations such as 

dry cleaning and metal degreasing; cis-1,2-DCE is used to make solvents and is a common breakdown product of 

PCE and TCE [Refs. 11, p. 1; 12, p. 1; 13, p. 1; 14, p. 16]. Chloroform is a common environmental contaminant 

21
GW-Observed Release

derived from various industrial and chemical processes, including as a byproduct of disinfecting water with chlorine

[Refs. 15, p. 1; 16, p. 1]. A review of previous analytical results for the Maguayo wells indicates detections of 

chloroform [Refs. 17, p. 1; 30 through 50]. Bromodichloromethane is also a common byproduct of water 

chlorination [Ref. 18, p. 1].

For the site-specific samples, all background and contaminated samples documenting the observed release were 

collected from the hydrologic unit being evaluated (i.e., the NCLAS upper aquifer) [Ref. 10, pp. 1−27, 47−53, 85]. 

That is, the sampled wells, whether background or release, withdraw water from the formations that compose the 

aquifer (specifically, the Aymamón Limestone, Aguada Limestone, and Cibao Formation) at a similar range of 

screened interval elevations with respect to mean sea level (MSL) [Ref. 10, pp. 3−27, 30, 50−52, 62−63, 77−82, 85, 

92]. In addition, the Vivoni well is located upgradient of all other wells and is screened in a similar relative position 

with respect to the top of the static water level (i.e., the water table); that is, the screened interval for the Vivoni well 

is 13 to 140 feet below the static water level, and the screened intervals for other background concentration wells 

and the release wells all fall within the range of 0 to 232 feet below the static water level [Figure 1; Refs. 4, p. 1; 10, 

pp. 3−27, 77-82; 21, p. 18; 22, p. 52]. The samples were all collected within a one-week period (September 22-28, 

2015) during a single sampling event [Refs. 6, pp. 3−13; 7, pp. 6, 33−39].

Based on these considerations, the well samples exhibiting background concentrations are considered to be 

representative of background levels within the NCLAS upper aquifer, and are used for comparison to the release 

samples collected from the Dorado Urbano system, Maguayo system, and water bottling plant wells that exhibit 

contamination. 

Background Concentrations

During the September 2015 sampling event, EPA collected ground water samples from the Dorado area wells, 

including the following wells that exhibited background concentrations [Refs. 6, pp. 5−6, 13, 19, 21−24, 32, 37; 7, 

pp. 3−6, 10, 18−19, 30−31, 37−38].

TABLE 3. BACKGROUND SAMPLE INFORMATION

Well 

Location

Ground 

Surface Elev.

(ft MSL)

Screened 

Interval 

(ft MSL)

Sample ID/

CLP Sample 

No.

Sample

Date

Reference(s)

Dorado Dairy 

2 

50 3.47 to -150 DGWC-GW01/ 

BCJQ1

09/22/2015 4, p. 1; 6, pp. 5, 21−22; 7, 

pp. 6, 10, 18; 10, pp. 3−4, 

30, 77−78

San Antonio 

2 

16.5 -29.5 to -69.5 DGWC-GW02/ 

BCJQ2

09/22/2015 4, p. 1; 6, pp. 6, 23−24; 7, 

pp. 6, 10, 19; 10, pp. 3−4, 

DGWC-GW19/ 25, 30

BCJR9

09/22/2015

Vivoni 230 157 to 30 DGWC-GW13/ 

BCJR3

09/25/2015 4, p. 1; 6, pp. 13, 32; 7, pp. 

6, 10, 30; 10, pp. 3−4, 6, 27, 

50−52

Higuillar 60 unknown to 

-140

DGWC-GW14/ 

BCJR4

09/28/2015 4, p. 1; 6, pp. 19, 37; 7, pp. 

6, 10, 31; 10, pp. 3−4, 30, 

62−63

ft MSL feet above/below mean sea level

22
GW-Observed Release

TABLE 4. BACKGROUND SAMPLE RESULTS

Sample ID/

CLP Sample 

No.

Hazardous Substance Level (μg/L) CRQL 

(μg/L)

Reference(s)

DGWC-GW01/ 

BCJQ1

Bromodichloromethane 0.50 U 0.50 7, pp. 6, 18, 33−34; 8, pp. 2−10, 

Chloroform 0.50 U 0.50 55; 51, pp. 2, 34−35 

cis-1,2-DCE 0.50 U 0.50

PCE 0.35 J 0.50

TCE 0.15 J 0.50

DGWC-GW02/ 

BCJQ2

Bromodichloromethane 0.50 U 0.50 7, pp. 6, 19, 33−34; 8, pp. 2−8, 

Chloroform 0.50 U 0.50 11−12, 55−56; 51, pp. 2, 48−49

cis-1,2-DCE 0.50 U 0.50

PCE 0.23 J 0.50

TCE 0.50 U 0.50

DGWC-GW19/ 

BCJR9 

Bromodichloromethane 0.50 U 0.50 7, pp. 6, 19, 33−34; 8, pp. 2−8, 

Chloroform 0.50 U 0.50 35−36, 65; 51, pp. 2, 59−60

cis-1,2-DCE 0.50 U 0.50

PCE 0.24 J 0.50

TCE 0.50 U 0.50

DGWC-GW13/ 

BCJR3

Bromodichloromethane 0.50 U 0.50 7, pp. 6, 30, 37−38; 8, pp. 2−8, 

Chloroform 0.50 U 0.50 33−34, 64; 51, pp. 4, 259−260

cis-1,2-DCE 0.50 U 0.50

PCE 0.50 U 0.50

TCE 0.50 U 0.50

DGWC-GW14/ 

BCJR4 

Bromodichloromethane 0.50 U 0.50 7, pp. 6, 31, 39, 41; 8, pp. 74−85, 

Chloroform 0.50 U 0.50 161; 52, pp. 2, 32−33 

cis-1,2-DCE 0.50 U 0.50

PCE 0.50 U 0.50

TCE 0.12 J 0.50

μg/L micrograms per liter

CRQL Contract-required quantitation limit, adjusted for sample and method [Ref. 8, pp. 3, 75]

U Indicates that the analyte was analyzed for, but was not detected at a level greater than or equal to the level 

of the adjusted CRQL for sample and method [Ref. 8, p. 3]. 

J The analyte was positively identified and the associated numerical value is the approximate concentration 

of the analyte in the sample (due to the concentration of the analyte was below the CRQL) [Refs. 8, pp. 3, 

75; 28, pp. 4−8].

23
GW-Observed Release

Contaminated Samples

During the September 2015 sampling event, EPA collected ground water samples from the Dorado area wells, and 

the results confirmed the presence of bromodichloromethane; chloroform; cis-1,2- DCE; PCE; and TCE at 

concentrations significantly above background levels [Refs. 6, pp. 3−13, 21−32, 37; 7, pp. 3−6, 10, 18−41; 8, pp. 

13−34, 56−65].

TABLE 5. RELEASE SAMPLE INFORMATION

Well 

Location

Ground 

Surface Elev. 

(ft MSL)

Screened 

Interval

(ft MSL)

Sample ID/

CLP Sample 

No.

Sample

Date

Reference(s)

San Antonio 

3 

16.5 -29.5 to -69.5 DGWC-GW03/ 

BCJQ3

09/23/2015 4, p. 1; 

10, 20; 

81−82

6, pp. 7, 24; 7, pp. 6, 

10, pp. 3−4, 24, 30, 

Maguayo 7 25 -55 to -115 DGWC-GW04/ 

BCJQ4

09/23/2015 4, p. 1; 6, pp. 8, 25−26; 7, 

pp. 6, 10, 21; 10, pp. 3−4, 

15−18, 30, 79−80, 85

Maguayo 6 35 -25 to -95 DGWC-GW05/ 

BCJQ5

09/23/2015 4, p. 1; 6, pp. 8, 26; 7, pp. 6, 

10, 22; 10, pp. 3−4, 11−14, 

30, 79−80, 85

Maguayo 2 121 -49 to -229 DGWC-GW06/ 

BCJQ6

09/23/2015 4, p. 1; 

10, 23; 

50−52

6, pp. 8, 27; 7, pp. 6, 

10, pp. 3−4, 6, 30, 

Nevárez 25 -15 to -115 DGWC-GW07/ 

BCJQ7

09/24/2015 4, p. 1; 6, pp. 9−10, 27−28; 

7, pp. 6, 10, 24; 10, pp. 3−4, 

19

Water 

bottling plant

60 unknown to 

-240

DGWC-GW08/ 

BCJQ8

09/24/2015 4, p. 1; 6, p. 11; 7, pp. 6, 10, 

25; 10, pp. 3−4, 92−95

Maguayo 4 95 30 to -65 DGWC-GW09/ 

BCJQ9

09/24/2015 4, p. 1; 6, pp. 11−12, 28, 31; 

7, pp. 6, 10, 26; 10, pp. 3−5, 

30, 50−52

Maguayo 3 98 18 to -62 DGWC-GW10/ 

BCJR0

09/24/2015 4, p. 1; 6, pp. 11−12, 29−30; 

7, pp. 6, 10, 27; 10, pp. 3−4, 

7−10, 30, 50−52

Santa Rosa 35 -25 to -70 DGWC-GW11/ 

BCJR1

09/24/2015 4, p. 1; 

6, 10, 

20−23, 

6, pp. 11−12; 7, pp. 

28; 10, pp. 3−4, 

30

Maguayo 5 60 unknown to -85 DGWC-GW12/ 

BCJR2

09/24/2015 4, p. 1; 6, pp. 11−12, 31−32; 

7, pp. 6, 10, 29; 10, pp. 3−4, 

30, 79−80

ft MSL feet above/below mean sea level

24
GW-Observed Release

Contaminated Samples (continued)

TABLE 6. OBSERVED RELEASE SAMPLE RESULTS

Sample

CLP

No.

ID/

 Sample 

Hazardous Substance Concentration

(μg/L)

CRQL 

(μg/L)

Reference(s)

DGWC-GW03/ 

BCJQ3

TCE 0.91 0.50 7, pp. 6, 35−36; 8, pp. 13, 56; 51, 

pp. 3, 98

DGWC-GW04/ 

BCJQ4

Chloroform 7.9 0.50 7, pp. 6, 35−36; 8, pp. 15−16, 57; 

cis-1,2-DCE 1.0 0.50 51, pp. 3, 112−113

PCE 3.8 0.50

TCE 0.50 0.50

DGWC-GW05/ 

BCJQ5 

Chloroform 11 0.50 7, pp. 6, 35−36; 8, pp. 17−18, 58; 

cis-1,2-DCE 1.2 0.50 51, pp. 3, 124−125

PCE 5.0 0.50

TCE 0.54 0.50

DGWC-GW06/ 

BCJQ6

Bromodichloromethane 7.9 0.50 7, pp. 6, 35−36; 8, pp. 3, 19−20, 

PCE 0.66 J- 0.50 59; 28, pp. 4−9, 12; 51, pp. 3, 138

DGWC-GW07/ 

BCJQ7

PCE 1.5 0.50 7, pp. 6, 37−38; 

51, pp. 4, 178

8, pp. 21−22, 60; 

DGWC-GW08/ 

BCJQ8

Chloroform 13 0.50 7, pp. 6, 37−38; 8, 

51, pp. 4, 188−189

pp. 23−24, 60; 

cis-1,2-DCE 1.1 0.50

PCE 3.7 0.50

DGWC-GW09/ 

BCJQ9

Chloroform 13 0.50 7, pp. 6, 37−38; 8, 

51, pp. 4, 200−201

pp. 25−26, 61; 

cis-1,2-DCE 1.3 0.50

PCE 7.6 0.50

DGWC-GW10/ 

BCJR0

Chloroform 24 2.5 7, pp. 6, 37−38; 8, 

51, pp. 4, 212−213,

pp. 

 225

27−28, 62; 

PCE 2.9 0.50

DGWC-GW11/ 

BCJR1

Chloroform 1.9 0.50 7, pp. 6, 37−38; 8, 

51, pp. 4, 236−237

pp. 29−30, 63; 

PCE 1.2 0.50

DGWC-GW12/ 

BCJR2

Chloroform 18 0.50 7, pp. 6, 37−38; 8, pp. 

63−64; 51, pp. 4, 247−248

31−32, 

cis-1,2-DCE 2.2 0.50

PCE 11 0.50

TCE 0.68 0.50

μg/L micrograms per liter

CRQL Contract-required quantitation limit, adjusted for sample and method [Ref. 8, pp. 3, 75]

J- The result is an estimated quantity that might be biased low. In accordance with the November 1996 EPA 

fact sheet "Using Qualified Data to Document an Observed Release and Observed Contamination”, the 

value is usable without adjustment [Refs. 8, p. 3; 28, pp. 4−8].

Hazardous Substances Released:

Bromodichloromethane CAS No. 000075-27-4 

Chloroform CAS No. 000067-66-3 

Cis-1,2-Dichloroethylene (cis-1,2-DCE) CAS No. 000156-59-2 

Tetrachloroethylene (PCE) CAS No. 000127-18-4 

Trichloroethylene (TCE) CAS No. 000079-01-6 

==================================================================================

Ground Water Observed Release Factor Value: 550

25
GW-Observed Release/Attribution

Attribution:

Due to the presence of multiple possible sources but no results for intervening areas, EPA has not yet identified a 

surface source of the ground water contaminants in the Dorado public supply wells. The site is located in a longdeveloped area where numerous possible source facilities have been identified [Refs. 24, pp. 1−15, 170; 25, pp. 3, 

15; 26, pp. 10−15]. Although EPA has performed sampling investigations at numerous facilities in the area [see 

“Other Possible Sources” below], there are no intervening data to directly connect possible source facilities to the 

supply well contamination. The heterogeneous nature of the karst limestone aquifer makes it difficult to determine 

where contamination originates or contaminant flow paths [Refs. 20, pp. 13, 32; 22, pp. 49−52, 60−61]. PCE and 

TCE are man-made chlorinated solvents that are commonly used in commercial/industrial operations such as dry 

cleaning and metal degreasing; cis-1,2-DCE is used to make solvents and is a common breakdown product of PCE 

and TCE [Refs. 11, p. 1; 12, p. 1; 13, p. 1; 14, p. 16]. Chloroform is a common environmental contaminant derived 

from various industrial and chemical processes, including as a byproduct of disinfecting water with chlorine [Refs.

15, p. 1; 16, p. 1]. A review of previous analytical results for the Maguayo wells indicates detections of chloroform 

[Ref. 17, p. 1]. Bromodichloromethane is an industrial chemical that is also a common byproduct of water 

chlorination [Ref. 18, p. 1].

In July 2009, PRASA completed a Sanitary Survey, which included an inventory of possible sources of pollution 

within 1 mile of supply well Maguayo 3 [Ref. 25, pp. 1−2, 17]. The majority of the facilities identified were auto 

repair/body shops and gas stations south of the well along Route 2, some of which also contained junkyards where 

scrap cars and miscellaneous metal debris are stored [Ref. 25, pp. 3, 15, 18]. Information gathered during the survey 

indicates that scrap metal, solid wastes, and used oils generated at these facilities are collected for recycling [Ref. 

25, pp. 3, 18]. Photographic documentation provided in the survey indicates poor housekeeping at some facilities

[Ref. 25, pp. 5−13]. The survey also identified two horse farms just north and south of Maguayo 3 where wastes are 

discharged directly to the ground surface; however, the types of wastes were not identified [Ref. 25, pp. 3, 15, 18]. 

EPA has investigated facilities throughout Dorado in multiple attempts to identify the source(s) of the ground water 

contaminants, including sample collection at facilities within and around the area of observed ground water 

contamination. In 2008, EPA launched the Maguayo Site Discovery Initiative (SDI) as an effort to identify possible

hazardous waste sites in the vicinity of the contaminated wells [Refs. 26, p. 3; 29, pp. 3−4]. After a sampling effort 

confirmed contamination in the Dorado area public supply wells, EPA conducted windshield surveys, file searches 

and reviews, and site reconnaissance activities to identify possible source facilities; based on these efforts, EPA

identified 21 facilities for further investigation [Refs. 26, pp. 10−15, 144−170; 29, pp. 3−5, 28]. In 2011 and 2013, 

EPA conducted Preliminary Assessment/Site Inspections (PA/SI) at the 21 facilities; in 2015, Site Reassessments 

(SR) were conducted at five of the facilities. Surface soil samples, subsurface soil samples, and ground water 

samples (if ground water was encountered) were collected from each facility; soil gas samples were collected at one 

active dry-cleaning facility [Refs. 30 through 50; see “Other Possible Sources” below]. Analytical results 

documented the presence or apparent presence of chlorinated solvents at several facilities, while there were no 

detections at other facilities (see Figure 2). Although some of the possible sources are more than 1 mile from the 

contaminated wells, the Dorado region is underlain by a karst aquifer. Pumping of supply wells could affect ground 

water flow over areas large enough to capture contamination from one or more distant sources in several directions, 

but there are no intervening data to clearly connect any of the possible sources to the well contamination [Figure 2; 

Refs. 20, pp. 3, 10, 13; 21, pp. 11−15; 22, pp. 8−12, 31, 36, 51−52, 63]. 

EPA also identified other industrial facilities in the vicinity of the ground water contamination, including: In-Mar 

Trading (within the area of observed ground water contamination); Department of Agriculture Diagnostics 

Laboratory (0.1 mile east-northeast); Mapei Caribe, Dorado Electroplating, Gulbrandsen Puerto Rico Inc., Prisma 

Print, and El Viejo Metal Recycling (all located approximately 1 mile south); Hi-Class Cleaners (1.1 miles north); 

Boston Scientific (1.5 miles north); and Biovail Laboratories International SRL (1.7 miles north) [Figure 2; Ref. 29, 

pp. 11−22]. A review of environmental databases identified additional possible sources in the vicinity of the site, 

including in the neighboring municipalities of Toa Baja to the east and Vega Alta to the west [Ref. 24, p. 170]. 

Although there is this multitude of facilities in the region that are or could be associated with the site contaminants, 

there is not sufficient evidence (i.e., data for intervening areas) to attribute the ground water contamination in the 

public supply wells to any specific facility(ies); therefore, there is no identified source(s) of contamination [Figures 

1 and 2; Ref. 1, pp. 51588, 51595]. Figure 2 shows the locations of possible source facilities.

26
GW- Observed Release/Other Possible Sources

Other Possible Sources

During the course of the investigations in 2011, 2013, and 2015, EPA detected contaminants of possible concern 

(COPC) in soil and shallow ground water samples at and near several nearby facilities located within 2 miles of the 

area of observed ground water contamination [Figure 2; Refs. 30 through 50]. All of the facilities investigated by 

EPA in 2011, 2013, or 2015, as well as the results of the investigations, are described below: 

Higuillar Dry Cleaners [Ref. 30]

Higuillar Dry Cleaners (HDC) (EPA ID No. PRN000206355) is a dry cleaning and laundry facility located 

within the area of observed ground water contamination. The business has been operating since 2004; 

previous use of the property was residential. The property contains a two-story building, with laundry and 

dry cleaning operations conducted within semi-enclosed rooms on the first floor and a residence on the 

second floor. A concrete-block septic tank, which protrudes approximately 1 foot above the ground surface 

on the northern side of the property, receives wastewaters from both the facility and the residence. In May 

2011, EPA observed that the owner was installing a new discharge pipe from the building to the septic tank 

and that an open trench on the northern portion of the property was full of raw wastewater [Figure 2; Ref. 

30, pp. 4−7]. 

In February 2015, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from five boreholes advanced at the HDC property using direct-push technology. Analytical results show 

the presence of chloroform (max. soil: 10 μg/kg; max. ground water: non-detect); cis-1,2-DCE (max. soil: 

170 J μg/kg; max. ground water: 1,000 μg/L); PCE (max. soil: 44 μg/kg; max. ground water: 380 μg/L); 

trans-1,2-DCE (max. soil: 3.6 J μg/kg; max. ground water: 17 μg/L); TCE (max. soil: 73 μg/kg; max. 

ground water: 330 μg/L); and vinyl chloride (max. soil: 150 μg/kg; max. ground water: 380 μg/L) [Ref. 30, 

pp. 17−23]. 

Green Point Sign & Screen Printing [Ref. 31]

Green Point Sign & Screen Printing (EPA ID No. PRN000206356) is a small print shop on residential land 

located within the area of observed ground water contamination. The 0.79-acre property also contains three 

occupied residential structures and a local bar; the print shop and residences/bar are connected to two 

separate on-site septic systems. Silk screen printing of T-shirts and ink plotting of large signs and 

billboards have taken place at the facility since the late 1990s. Chemicals used during operations include 

Tekmar Formula TS-3TM (a spot cleaning solution that contains up to 15% by weight PCE), H-7 (a 

degreaser), and 2-butoxyethyl acetate. The facility operator stated that waste inks and spent cleaning 

solutions are returned to the manufacturer for disposal. EPA has observed stressed vegetation and ink 

staining on the property. A USGS piezometer (ID: USGS 182548066164401 Piezometer Maguayo 2 

Dorado, PR) lies south of the property; the piezometer is screened from 105 to 110 feet bgs [Figure 2; Ref. 

31, pp. 3−6]. 

In March 2013, EPA collected soil samples for VOC analysis from on-site and off-site locations using 

direct-push technology, and ground water samples from the USGS piezometer near the south side of the 

property. Analytical results for all soil samples indicated non-detect values for environmental VOC 

parameters. The two ground water samples collected from the USGS piezometer indicated estimated 

concentrations of PCE (2.9 μg/L and 3.2 μg/L, respectively) and concentrations of chloroform (5.7 μg/L 

and 5.8 μg/L, respectively) [Ref. 31, pp. 13−17].

27
GW- Observed Release/Other Possible Sources

PRIDCO Block No: L-439-0-97 [Ref. 32]

The PRIDCO Block No: L-439-0-97 property (EPA ID No. PRN000206371) consists of 155 acres of 

vegetated, mostly undeveloped land located along the western edge of the area of observed ground water 

contamination. Karst features, such as limestone outcroppings and mogotes, are located on the periphery of 

the property. Available background information and historical aerial photos suggest that the property was 

used historically for agricultural purposes. After purchasing the property in 1998, PRIDCO conducted 

Phase II ESA soil sampling and installation of three on-site monitoring wells at the property in 1998 and 

2002. Observations from the Phase II ESA identified evidence of dumping, the presence of inorganic 

analytes at concentrations above EPA Soil Screening Levels (SSL), and detections of TCE in the 

monitoring wells ranging from 1.5 μg/L to 13.1 μg/L. Development of the property for a warehousing 

facility began in 2015; improvements include two on-site retention ponds and a paved access road equipped 

with storm drains, street lighting, and fire hydrants [Figure 2; Ref. 32, pp. 4−7]. 

In February 2011, EPA collected surface and subsurface soil samples from 13 boreholes advanced 

throughout the property using direct-push technology. During pre-sampling activities, EPA observed onsite debris piles and discovered that soil fill had been brought to the property to level the grade for the 

proposed industrial park. Analytical results indicated the presence of arsenic, chromium, and other metals 

at concentrations significantly above background, with the highest concentration of arsenic (101 mg/kg) 

detected in a surface soil sample collected next to an on-site debris pile. The concentrations of arsenic 

exceed EPA SSLs for outdoor worker exposure and migration to ground water. In January 2015, EPA 

collected surface soil and subsurface soil samples for VOC analysis from direct-push boreholes co-located 

with the 13 boreholes advanced during the 2011 sampling event. Sample results indicate non-detect values 

for all environmental VOC parameters. Ground water was not encountered within 50 feet of the ground 

surface in either 2011 or 2015, and the former monitoring wells could not be located [Ref. 32, pp. 8, 

19−38] 

Adriel Auto [Ref. 33]

Adriel Auto (EPA ID No. PRR000019422) is a car dealership located approximately 0.8 mile southsoutheast of the area of observed ground water contamination. Adriel Auto has been selling automobiles 

and performing general automotive maintenance and repair services at the property since the early 1980s; a

used car dealership reportedly operated on the property prior to Adriel Auto. The on-site parking lot was 

built over an unnamed intermittent stream, which now flows through a culvert that exits out of the wall on 

the property’s northern boundary. Chlorinated solvents are not currently used for degreasing at Adriel 

Auto; it is unknown if they were used in the past. Degreasing is conducted with commercially available 

citrus- and silicon/naphtha-based cleaners. An aboveground storage tank within secondary containment 

holds used oil and is located in the vehicle service area. There are two grease traps in the floor of the 

vehicle service area; overflow from the grease traps enters an overflow pipe that drains into one of two 

septic tanks located on the property. The operator reported that the grease traps are routinely emptied. 

During an on-site reconnaissance in 2009, EPA observed staining on the head of the overflow pipe [Figure 

2; Ref. 33, pp. 3−6]. 

In February 2013, EPA collected soil and ground water samples for VOC analysis from on-site and off-site 

locations using direct-push technology. The sampling team observed petroleum-like odors and PID 

readings above background at depths greater than 8 feet in two boreholes (S04 and S06) advanced in the 

vicinity of the on-site septic tanks. A layer of light non-aqueous phase liquid (LNAPL), approximately 

0.95 feet thick, was encountered on the water table at borehole S06; some of this brownish-black LNAPL 

was entrained in ground water sample 2026-GW06 from the borehole. Analytical results indicate that 

several VOCs were present in the soil and ground water samples from boreholes S04 and S06, including 

petroleum-related compounds (i.e., benzenes and xylenes) and solvents (i.e., acetone, 2-butanone, and 

estimated concentrations of cis-1,2-DCE) [Ref. 33, pp. 6, 15−21].

28
GW- Observed Release/Other Possible Sources

Metal Machining Co., Inc [Ref. 34]

Metal Machining Co. Inc (EPA ID No. PRR000012674) is located approximately 1 mile south of the area 

of observed ground water contamination. The facility consists of a single structure, which houses 

administrative offices, engineering offices, and a machine shop; it is situated at the base of a limestone hill 

(i.e., mogote). Runoff from the property flows to a sinkhole adjacent to the western boundary of the 

property and into a storm drain adjacent to the southern boundary. Operations consist of designing, 

fabricating, and installing custom machines and machine parts; machine shop equipment includes lathes, 

milling machines, grinders, and a welding area. Degreasing of metal parts is conducted over a selfcontained sink using commercial degreasers; acetone is also used. Used cutting oils, solvents, and 

hydraulic fluids are reportedly transported off-site by a permitted transporter, whereas process waters and 

sewage are discharged to a septic system on the eastern side of the facility. Metal Machining Co. Inc. has 

been operating since the owners bought the property in 1999, prior to which the property was vacant for 

approximately 10 years. According to a Metal Machining representative, the facility was used to 

manufacture Coca-Cola flavoring prior to the nonoperational period [Figure 2; Ref. 34, pp. 3−6]. 

In March 2013, EPA collected soil samples for VOC and TAL Inorganics analyses from four on-site 

locations and one off-site location using direct-push technology. VOCs were not detected in any soil 

samples collected from either on-site or off-site locations. Inorganic analyses indicated the presence of 

cobalt, lead, manganese, and nickel at concentrations greater than three times background levels. The 

inorganic concentrations are below EPA SSLs appropriate to the facility, with the exception of nickel 

exceeding the migration to ground water SSL [Ref. 34, pp. 6, 14−20].

Narvaez Cleaners and Tailoring [Ref. 35]

Narvaez Cleaners and Tailoring (EPA ID No. PRN000206357) is a dry-cleaning facility located 

approximately 1.2 miles north of the area of observed ground water contamination. The facility consists of 

a two-story concrete storefront building and concrete parking lot located in a mixed commercial and 

residential area of downtown Dorado. Narvaez Cleaners and Tailoring has operated the facility since 2000, 

prior to which El Dorado Dry Cleaning operated out of the building. The dry cleaning facility occupies the 

first floor and the second floor is a vacant residential space. In August 2009, the facility operator informed 

EPA and provided evidence that two to three 55-gallon drums of PCE are consumed per year in one drycleaning machine, that the machine is emptied and cleaned once per year, and that the waste is drummed 

for disposal. EPA observed four drums labeled “Hazardous Waste” within the facility in August 2009 and 

drums of PCE within the facility in March 2013 [Figure 2; Ref. 35, pp. 3−6]. 

In March 2013, EPA collected soil samples from five boreholes advanced at and in the immediate vicinity 

of the facility using direct-push technology. EPA also collected two sub-slab soil vapor samples beneath 

the facility. Analytical results indicated the presence of cis-1,2- DCE at 6.0 μg/kg in soil sample 2024-S05 

(depth: 6-6.5 ft bgs) and at estimated concentrations in two other soil samples, at depths of 10.5-11 ft bgs 

and 13.5-14 ft bgs. PCE and its degradation products (i.e., TCE; cis-1,2-DCE; trans-1,2-DCE; 1,1-DCE; 

and vinyl chloride) were detected at elevated levels in the sub-slab soil vapor samples. Several petroleumrelated VOCs were also detected in the soil vapor samples. EPA returned to the facility in September 2015 

to collect soil samples beneath the building. Analytical results from sub-slab locations beneath the cleaning 

room (i.e., Borehole 1) and the former drum storage area (i.e., Borehole 2) indicate the presence of PCE 

(max. 750 μg/kg), TCE (max. 62 μg/kg), cis-1,2-DCE (max. 49 μg/kg), trans-1,2-DCE (max. 6.2 μg/kg), 

and vinyl chloride (max. 7.3 μg/kg) [Ref. 35, pp. 14−18].

29
GW- Observed Release/Other Possible Sources

Laundry Espinosa [Ref. 36]

Laundry Espinosa (EPA ID No. PRN000206358) is an active dry cleaning and laundry facility located in a 

strip mall approximately 1.2 miles south-southwest of the area of observed ground water contamination. 

The facility building contains two units, with Laundry Espinosa in the northwest unit and an after-school 

tutoring center in the southeast unit. The building is built on a hillside, with the storefronts facing northeast 

at street level, and the basement doors facing southwest. The facility has been operating at the current 

location since the 1980s. A hydrocarbon-based solvent, ExxsolTM D40 fluid, is utilized by the business; it is 

unknown if the facility has historically used other materials such as PCE for dry cleaning operations. In 

August 2009, March 2011, and May 2011, no wastes were observed to be generated or stored, and no signs 

of spills or discharges were noted [Figure 2; Ref. 36, pp. 4−7]. 

In February 2015, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from five boreholes advanced throughout the property using direct-push technology. Ground water was 

reached in three of five boreholes, at depths ranging from 28 to 36 feet. Analytical results indicated nondetect values or estimated values below the RDL for all VOC parameters, with the exception of chloroform 

at 29 micrograms per liter (μg/L) in one ground water sample. There was a single estimated concentration 

of PCE below the RDL in one surface soil sample [Ref. 36, pp. 16−19]. 

PRIDCO Building No: T-0320-0-56 [Ref. 37]

PRIDCO Building No: T-0320-0-56 (EPA ID No. PRN000206380) is currently occupied by Embos, Inc. 

(a.k.a. Puerto Rico Traction Tires), an inactive tire repair and retreading business that operated at the 

facility from 1964 until 2010. It is located approximately 1.2 miles northeast of the area of observed 

ground water contamination. Three septic tanks are located on the south side of the property, most of 

which is unpaved with piles of used tires and black patches of shredded tires scattered around. The facility 

was constructed by PRIDCO in the mid-1950s. According to PRIDCO records, the facility was occupied 

by EMT Fittings in 1960 and was sold to the current owner in January 2000. The current owner operated 

under the names America Boschetti Bitter, Embos, Inc., and Puerto Rico Traction Tires. The only 

environmental work known to be conducted is the removal and closure of a fuel oil UST in 1998. 

However, no post-excavation analytical data or other documentation regarding the integrity of the tank is 

included in the available closure report [Figure 2; Ref. 37, pp. 3−6]. 

In October 2010, EPA confirmed that the facility is an inactive tire repair and retreading facility during an 

on-site reconnaissance. No hazardous waste or obvious signs of contamination were observed on the 

exterior portions of the property. However, black patches of apparent shredded tires were observed 

scattered throughout the property during the subsequent sampling event. In February 2011, EPA collected 

surface soil, subsurface soil, and ground water samples from five boreholes advanced throughout the 

property using direct-push technology. The samples were analyzed for VOCs through the EPA CLP. The 

analytical results indicated low, estimated concentrations of ethylbenzene and o-xylene in one surface soil 

sample and low, estimated concentrations of toluene and xylenes in three ground water samples. Analytical 

results indicated non-detect values for remaining VOC parameters, including PCE and TCE, in the soil and 

ground water samples [Ref. 37, pp. 6, 13−17].

PRIDCO Building No:S-0050-0-51 [Ref. 38]

PRIDCO Building No: S-0050-0-51 (EPA ID No. PRN000206379) is currently occupied by a National 

Hardware business, which includes a lumber yard and home center. It is located approximately 1.3 miles 

northeast of the area of observed ground water contamination. The property contains two buildings: one 

houses the hardware store and the other features a gardening center and a bedding supply store. According 

to PRIDCO records, the facility was constructed in the early 1950s by PRIDCO and was sold to Hicker of 

Puerto Rico (HPR) in February 1980. However, available on-line databases do not have records of HPR’s 

operations. In addition, no information is available in PRIDCO’s files regarding previous facility

occupants during their ownership of the property [Figure 2; Ref. 38, pp. 3−6]. 

30
GW- Observed Release/Other Possible Sources

In October 2010, EPA conducted an on-site reconnaissance at the property. Observations indicated that the 

facility includes a retail hardware store and lumber yard and that no hazardous waste is generated. No 

obvious signs of contamination were noted. In February 2011, EPA collected surface soil, subsurface soil, 

and ground water samples for VOC analysis from five boreholes advanced throughout the property using 

direct-push technology. Analytical results indicated non-detect values for all environmental VOC 

parameters [Ref. 38, pp. 3, 13−17].

Former Narvaez Cleaners and Tailoring Facility [Ref. 39]

Former Narvaez Cleaners and Tailoring Facility (EPA ID No. PRN008008773) was a retail/commercial dry 

cleaning business that operated for an unknown length of time in the Dorado del Mar shopping center, 

approximately 1.5 miles north of the area of observed ground water contamination. A Subway restaurant 

with drive-through is currently in operation at this location; a Goodyear automotive maintenance facility 

operates out of the northwest portion of the building; there is a vacant storefront between the two 

aforementioned businesses. Additional shops, including a dry cleaning business (i.e., 5 Asec Cleaners), are 

located within the Dorado Del Mar shopping center [Figure 2; Ref. 39, pp. 3−6]. 

In March 2013, EPA personnel collected soil and ground water samples for VOC analysis from seven 

boreholes advanced at and in the vicinity of the facility. Analytical results indicated the presence of vinyl 

chloride at 14 μg/kg and cis-1,2-DCE and trans-1,2-DCE at estimated concentrations in one soil sample 

collected at depth 8.5−9.0 feet bgs adjacent to the former dry-cleaning facility The detection of acetone and 

2-butanone in the samples are considered to be an indication of lab contaminants [Ref. 39, pp. 13−18].

Edward’s Dry Cleaners Toa Baja [Ref. 40]

The Edward’s Dry Cleaners Toa Baja (EDCTB) facility (EPA ID No. PRN000206360) is a former dry 

cleaning and laundry facility located in a residential neighborhood in Toa Baja, approximately 1.8 miles 

east-northeast of the area of observed ground water contamination. The dry cleaner operated at the location 

from approximately September 2008 until sometime between 2011 and 2014; the facility is not known to 

have a prior history of industrial activity. In August 2009, EPA observed a 55-gallon drum of unused PCE 

at the facility. The facility lacked the required PREQB operating permits and no information was available 

to document proper disposal of PCE. In March 2011, cleaning operations were being conducted in an 

open-air concrete building. Drain pipes for the laundry discharged to the ground surface behind the 

building. EPA observed an open PCE drum in the driveway and detected a chemical odor. The property 

owner indicated that the PCE drum had just been cleaned on the driveway, but no other signs of spills or 

leaks were noted. In December 2014, the facility owner informed EPA that the facility had been shut down 

by PREQB due to lack of air quality permits required for operation of the on-site generator. Dry cleaning 

and laundry operations had ceased; the 55-gallon drum of PCE was not observed, nor was any other 

container of cleaning product observed [Figure 2; Ref. 40, pp. 4−7]. 

In February 2015, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from three boreholes advanced throughout the property using direct-push technology and stainless-steel 

hand augers. Analytical results indicated chloroform at 7.1 μg/kg in one soil sample. All other results for 

COPCs in soil and ground water samples were non-detect [Ref. 40, pp. 15−19].

The following facilities investigated by EPA in 2011 or 2015 are located in the PRIDCO Dorado Industrial Park 

approximately 1.1 to 1.4 miles north of the area of observed ground water contamination. There appears to be one 

or more sources of contamination within the industrial park (see Figure 2): 

31
GW- Observed Release/Other Possible Sources

PRIDCO Lot Nos: L-107-2-64-16/18/19 [Ref. 41]

PRIDCO Lot Nos: L-107-2-64-16/18/19 (EPA ID No. PRN000206382) contains a large industrial facility 

occupied by Fortex/Fortiflex (Fortiflex), which manufactures reinforced rubber pails and tubes, and 

Ballester Hermanos (BH), which operates a refrigerated warehouse and distribution center for frozen 

grocery products. The property was formerly owned by PRIDCO, which sold it to Ecolab in 1988; Ecolab 

is a provider of industrial and medical hygiene-related products and services. Fortiflex purchased the 

facility in 1999, and is classified as a CESQG under RCRA (ID No. PRR000016360). During an on-site 

reconnaissance by EPA in August 2009, spent lubricants were being stored in a 300-gallon AST with 

secondary containment (concrete basin) pending shipment off the property. The tank was full, and excess 

lubricants were stored in buckets adjacent to the tank; minor staining was observed. Degreasing in the 

manufacturing area was conducted using D4®, a commercial kerosene-based degreaser. EPA observed a 

1,000-gallon AST without secondary containment on the north side of the facility; Fortiflex indicated that 

the tank was from Ecolab’s operations and was not used by Fortiflex. EPA also observed a former waste 

storage area used by Ecolab in the southeastern corner of the property; the area consisted of a fenced, 

concrete pad covered by a roof. In October 2010, EPA observed that conditions had changed significantly 

since the 2009 inspection. The open, grassy area on the east side of the property was now occupied by 

BH’s refrigerated warehouse and distribution center; the 1,000-gallon AST had been removed; and the 

former waste storage area had been removed and paved over [Figure 2; Ref. 41, pp. 3−6]. 

In February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from five boreholes advanced throughout the property using direct-push technology. Analytical results 

indicated the presence of a low, estimated concentration of dichlorodifluoromethane (Freon 12) in a surface 

soil sample collected near the refrigerated warehouse and distribution center; a low, estimated 

concentration of carbon disulfide in a surface soil sample collected near the former location of the waste 

storage area; and low, estimated concentrations of carbon disulfide in ground water samples collected from 

a borehole advanced east of the warehouse. Neither PCE nor TCE was detected in any of the soil or ground 

water samples collected from the property [Ref. 41, pp. 15−19].

PRIDCO Building No. T-1125-0-73 and T-1125-1-79 [Ref. 42]

PRIDCO Building No. T-1125-0-73 and T-1125-1-79 (EPA ID No. PRN000206385) is a light industrial 

facility owned by PRIDCO and located approximately 1.1 miles north of the area of observed ground water 

contamination. The facility was built in the 1970s to early 1980s. Information obtained from PRIDCO 

indicates that Five Star Products, Inc. used the facility to manufacture costume jewelry from 1974 to 1993. 

In 1979, Five Star disclosed that TCE was used at the facility as a degreaser. Five Star was assigned 

RCRA Handler ID No. PRD987372919. During its operations, Five Star operated an on-site wastewater 

treatment system; raw wastewaters were collected and discharged from the facility via a floor trench 

collection system to a pair of 500-gallon sumps, pending pH adjustment and transfer to additional treatment 

tanks. From 1994 to approximately 2008, the facility was occupied by Ecolab, a provider of industrial and 

medical hygiene-related products and services; there is no known hazardous waste activity related to 

Ecolab’s operations at the facility. The facility is currently occupied by ProMed, which manufactures 

molded silicone and plastic components for medical implants; ProMed uses only small amounts of heptanes 

and alcohols in its manufacturing processes; chlorinated solvents are not used [Figure 2; Ref. 42, pp. 3−6]. 

In February 2011, WESTON collected surface soil, subsurface soil, and ground water samples for VOC 

analysis from direct-push boreholes advanced along the perimeter of the building and within the rear 

warehouse technology. Analytical results indicate the presence of vinyl chloride in the soil and ground 

water samples. Vinyl chloride was detected in a soil sample (9.9 μg/kg) and in four ground water samples 

(5.1 μg/L, 2.1 J μg/L, 2.1 J μg/L, and 1.4 J μg/L) [Ref. 42, pp. 13−20].

32
GW- Observed Release/Other Possible Sources

PRIDCO Building No: S-0745-0-66 [Ref. 43]

PRIDCO Building No: S-0745-0-66 (EPA ID No. PRN000206381) is a light industrial property located 

approximately 1.2 miles north of the area of observed ground water contamination. The facility was 

constructed in the mid-1960s. Information obtained from PRIDCO indicates that the facility was occupied 

by Claxbox of PR, Inc. (Claxbox) from 1982 to 1984 and Dorado Carton Co., Inc. (DCC) from 1993 to 

2001; both companies manufactured boxes and crates. In July 2008, EPA observed a sign indicating that 

the facility was formerly occupied by Advanced Windows. A review of EPA on-line databases did not 

reveal any information regarding hazardous waste activity for Advanced Windows. Available information 

in 2011 indicated that the facility was leased to the Municipality of Dorado and slated to be used as an 

emergency response center; however, the property was vacant during EPA on-site sampling in 2011 [Figure 

2; Ref. 43, pp. 3−6]. 

In February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis

from five boreholes advanced throughout the property using direct-push technology. Analytical results 

indicated non-detect values for all environmental VOC parameters for the soil and ground water samples

[Ref. 43, pp. 13−17].

PRIDCO Buildings No: S-1166-0-74 and S-1166-0-80 [Ref. 44]

PRIDCO Buildings No: S-1166-0-74 and S-1166-0-80 (EPA ID No. PRN000206383) is an inactive, light 

industrial facility owned by PRIDCO and located approximately 1.2 miles north of the area of observed 

ground water contamination. The original portion of the facility (S-1166-0-74) was built in 1975, and 

building extension S-1166-0-80 was built in the early 1980s. PRIDCO records indicate that the facility was 

occupied by Economic Laboratories (July 1974 - June 1989), which manufactured detergent dispensers 

using plastic injection molding; M.A. International Manufacturing (early 1990s), which likely used the 

facility for manufacturing plastic components for industry; Ecolab Manufacturing (April 1994 - September 

1994), which manufactured industrial hygiene equipment; Harvey Hubbell Caribe, Inc. (March 1995 - 

October 2000), which manufactured electrical components; and Omega Systems (unknown date to 

September 2008), which manufactured plastic water tanks. Harvey Hubbell Caribe, Inc. was assigned 

RCRA ID No. PRR000007104 and generated the following wastes: isopropanol, zinc compounds, and 

spent fluorescent light bulbs [Figure 2; Ref. 44, pp. 3−6]. 

From 2009 to 2011, EPA observed the property to be in a state of disrepair. On February 18, 2011, EPA 

personnel collected surface soil, subsurface soil, and ground water samples for VOC analysis from six 

boreholes advanced throughout the property using direct-push technology. With the exception of estimated 

concentrations of styrene (0.6 J μg/kg) and m, p-xylene (0.2 J μg/kg) in two surface soil samples, soil and 

ground water sample analytical results indicated non-detect values for all environmental VOC parameters

[Ref. 44, pp. 3, 6, 13−18].

PRIDCO Building No. T-1322-0-88 [Ref. 45]

PRIDCO Building No. T-1322-0-88 (EPA ID No. PRN000206384) is an active, light industrial facility 

owned by PRIDCO and located approximately 1.2 miles north of the area of observed ground water 

contamination. Information obtained from PRIDCO indicates that the facility was constructed in 1981 and 

was occupied by Playtex Dorado from 1981 to approximately 2003. Playtex Dorado used the facility for 

the manufacture of women’s undergarments. Additional information provided by PRIDCO indicates that 

the facility was occupied by Provimi de Puerto Rico (Provimi) during an unknown time period; Provimi 

conducted meat processing and packaging [Figure 2; Ref. 45, pp. 3−6]. 

33
GW- Observed Release/Other Possible Sources

In August 2009 and October 2010, EPA observed the facility to be inactive and in a state of disrepair. In 

February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from six boreholes advanced throughout the property using direct-push technology. Soil sample analytical 

results indicated non-detect values for all environmental VOC parameters. With the exception of one 

detection of 1,1-DCE at an estimated concentration below the SQL, ground water analytical results 

indicated non-detect values for all environmental VOC parameters. At the time of the sampling event, the 

facility was in the process of being renovated for Provimi to reoccupy the facility and resume meat 

processing and packaging operations in January 2012; Provimi did not anticipate generating hazardous 

waste as part of its business operations [Ref. 45, pp. 3, 6, 13−18].

PRIDCO Buildings No: T-0638-0-66 and T-0638-1-67 [Ref. 46]

PRIDCO Buildings No: T-0638-0-66 and T-0638-1-67 (EPA ID No. PRN000206375) is a light industrial 

property owned by PRIDCO and located approximately 1.2 miles north of the area of observed ground 

water contamination. PRIDCO records indicate that Newell manufactured metal wire products at the 

facility from 1967 to 1984; PRWRA occupied the facility from 1984 to 1985 (no information is available 

regarding PRWRA’s operations); Playtex manufactured women’s undergarments and used 1,1,1-TCA and 

naphtha-based solvents in the process from 1985 to 1994; and Omega manufactured plastic tanks from 

1997 to 2002. The facility is currently occupied by Heraeus (a.k.a. Synosis Caribe; a.k.a. Heraeus 

Materials Caribe), which manufactures and assembles electrical coils and wires for medical devices such as 

pacemakers. The electrical components manufactured by Heraeus are cleaned in acid and alkaline baths 

using hydrochloric acid and hydrogen phosphate solutions, respectively; chlorinated solvents are not used. 

Spent acid and alkaline solutions are neutralized on-site in an evaporation unit. Products are polished using 

sodium and potassium salts, which are stored as non-hazardous waste in the storage shed pending shipment 

off the property. Small amounts of isopropyl alcohol and glycol are also used in the manufacturing 

process. Heraeus is classified as an SQG under RCRA (ID No. PRR000017202) [Figure 2; Ref. 46, pp. 

4−7]. 

In January 2015, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from six boreholes advanced throughout the property using direct-push technology. Analytical results 

indicated non-detect values for all chlorinated VOC parameters of concern for all soil and ground water 

samples, with the exception of chloroform detected at an estimated concentration of 0.74 J μg/kg in one 

soil sample [Ref. 46, pp. 16−21]. 

PRIDCO Buildings # T-0957-0-68/ T-0957-1-71/T-0957-2-72/T-1053-0-73/T-1053-1-90 [Ref. 47]

PRIDCO Buildings # T-0957-0-68/T-0957-1-71/T-0957-2-72/T-1053-0-73/T-1053-1-90 (EPA ID No. 

PRN000206372) is an inactive light industrial facility owned by PRIDCO and located approximately 1.3 

miles north of the area of observed ground water contamination. The facility consists of two buildings 

constructed in the late 1960s and early 1970s, with an addition in the early 1990s; Emerson occupied both 

buildings from an unknown date until 2006 or 2007. Emerson manufactured electrical components for 

residential and commercial environmental controls, including mercury-containing thermostats and 

semiconductors. Emerson used 1,1,1-TCA, dichloromethane, lead, mercury, and xylenes in its operations, 

and the facility was classified as a RCRA CESQG (ID No. PRD090066234). The rear facility has been 

vacant since Emerson left in 2007; the front facility was occupied by Impresos Quintana, a commercial 

printing business that specialized in brochures, stationery, and business cards, from 2008 to 2010. In 

September 2009 and October 2010, EPA observed that the computer-assisted printing machines used at the 

facility were cleaned with water-based cleaners and commercial alcohol substitute cleaners, that there was 

no silk screening or use of chlorinated solvents, and that the facility was clean and well-maintained. 

Impresos Quintana was in the process of shutting down operations and vacating the facility in October 

2010 [Figure 2; Ref. 47, pp. 3−6]. 

34
GW- Observed Release/Other Possible Sources

In February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from eight boreholes advanced throughout the property using direct-push technology. Analytical results 

indicated the presence of low, estimated concentration of PCE and TCE in subsurface soil and ground 

water samples [Ref. 47, pp. 13−18]. 

PRIDCO Building Nos: S-0838-0-67 and T-0998-0-74 [Ref. 48]

and Former Edward’s Dry Cleaners Facility Dorado [Ref. 49] 

PRIDCO Building Nos: S-0838-0-67 and T-0998-0-74 (EPA ID No. PRN000206373) is a former light 

industrial property that has been redeveloped into commercial properties. It is located in downtown 

Dorado, approximately 1.3 miles north of the area of observed ground water contamination. The PRIDCOowned buildings formerly located on the property were built in the late 1960s to mid-1970s; PRIDCO sold 

the two buildings to Emulex in February 1984. Emulex manufactured data communication equipment, 

including computer-printed circuit boards, under RCRA ID No. PRD071807408, ceasing its Puerto Rico 

operations in 1998. The subject property is currently divided into two separately-owned commercial 

properties: the southern portion (former location of PRIDCO Building No. S-0838-0-67) is occupied by a 

CVS pharmacy; the northern portion (former location of PRIDCO Building No. T-0998-0-74) is occupied 

by part of the Mahi-Mahi Shopping Village, a strip mall with various retail businesses including 

restaurants, eye care, a paint store, and a salon [Figure 2; Ref. 48, pp. 3−6]. The Mahi-Mahi Shopping 

Village, Location # 6 is the location of Former Edward’s Dry Cleaners Facility Dorado, where PCE-based 

dry cleaning was conducted from approximately 2005 to 2008 [Ref. 49, pp. 3−6]. 

In February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from eight boreholes advanced throughout the property using direct-push technology. With the exception 

of one detection of cis-1,2-DCE at an estimated concentration (1.6 J μg/kg) in a subsurface soil sample, soil 

and ground water sample analytical results indicated non-detect values for all environmental VOC 

parameters excluding common laboratory contaminants such as acetone [Ref. 48, pp. 15−20]. 

PRIDCO Building Nos: T-0868-0-67 and T-0868-1-69 [Ref. 50]

PRIDCO Building Nos: T-0868-0-67 and T-0868-1-69 (EPA ID No. PRN000206374) is a former light 

industrial property located approximately 1.4 miles north of the area of observed ground water 

contamination. During PRIDCO’s ownership, the facility consisted of one building constructed in the late 

1960s and early 1970s. Information obtained from PRIDCO indicates that it was sold to Centronics, a 

manufacturer of computer printers, in February 1977. The Centronics facility was assigned RCRA ID No. 

PRD090525866, but generator status and hazardous waste information are not listed in the RCRA database. 

The property is currently occupied by a Walgreens pharmacy within the Mahi-Mahi Shopping Village, a 

retail shopping center, and it is owned by IGI, a commercial property management company [Figure 2; Ref. 

50, pp. 3−6]. 

In February 2011, EPA collected surface soil, subsurface soil, and ground water samples for VOC analysis 

from four boreholes advanced throughout the property using direct-push technology. Soil sample 

analytical results indicated non-detect values for all VOC parameters. However, ground water sample 

analytical results indicated the presence of TCE, 1,1-DCE, cis-1,2-DCE, and 1,1,2-trichloro-1,2,2-

trifluoroethane [Ref. 50, pp. 13−17]. 

35
GW-Waste Characteristics

3.2 WASTE CHARACTERISTICS

3.2.1 Toxicity/Mobility

TABLE 7. TOXICITY/MOBILITY

Hazardous Substance

Source 

Numbers

Toxicity 

Factor Value

Mobility 

Factor Value

Toxicity/ 

Mobility Reference(s)

Bromodichloromethane 1, OR 100 1.0 100 2, p. 1

Chloroform 1, OR 100 1.0 100 2, p. 2

cis-1,2-Dichloroethylene 1, OR 1,000 1.0 1,000 2, p. 3

Tetrachloroethylene 1, OR 100 1.0* 100 2, p. 4

Trichloroethylene 1, OR 1,000 1.0 1,000 2, p. 5

OR = Observed Release

* Karst value is used due to karst aquifer being evaluated (see Section 3.0.1).

3.2.2 Hazardous Waste Quantity

TABLE 8. HAZARDOUS WASTE QUANTITY – GROUND WATER PATHWAY

Source Number Source Hazardous Waste Quantity 

(HWQ) Value (Section 2.4.2.1.5)

Is source hazardous constituent 

quantity data complete? (yes/no)

1 >0 No

Sum of Values: 1 (rounded to 1 as specified in HRS Section 2.4.2.2)

The sum corresponds to a hazardous waste quantity factor value of 1 in Table 2-6 of the HRS [Ref. 1, p. 51591]. 

However, based on the fact that targets are subject to Level I concentrations (see Section 3.3.2.3), a hazardous waste 

quantity factor value of 100 is assigned if it is greater than the hazardous waste quantity value from Table 2-6 of the 

HRS (i.e., 1) [Ref. 1, pp 51591-51592]. Therefore, a hazardous waste quantity factor value of 100 is assigned for 

the ground water pathway [Ref. 1, pp 51591-51592]. 

Hazardous Waste Quantity Factor Value: 100

3.2.3 Waste Characteristics Factor Category Value

==================================================================================

Cis-1,2-dichloroethylene and trichloroethylene correspond to the toxicity/mobility factor value of 1,000, as shown 

previously (see Section 3.2.1).

Toxicity/Mobility Factor Value (1,000) x Hazardous

Waste Quantity Factor Value (100): 1 x 105

The product (1 x 105

) corresponds to a Waste Characteristics Factor Category Value of 18 in Table 2-7 of the HRS 

[Ref. 1, p. 51592].

Waste Characteristics Factor Category Value: 18

36
GW-Targets

3.3 TARGETS

Note: Populations are apportioned only to the active wells within the ground water plume; the consideration of 

inactive wells as standby wells and subsequent population apportionment would not increase the site score. 

However, it should be noted that PRASA has raised the possibility of reactivating some wells.

The Maguayo water supply system consists of three active wells (i.e., Maguayo 2, Maguayo 6, and Maguayo 7) and 

one surface water source (i.e., the super aqueduct) contributing to a blended system that serves a population of 

36,630 [Ref. 10, pp. 1−98]. No single component contributes more than 40 percent of the total system production, 

so the system population is apportioned equally among the active system components (i.e., each active well is 

apportioned a population of 9,157.5 people) [Refs. 1, p. 51603; 10, pp. 1−4, 37−40]. The Dorado Urbano water 

supply system consists of two active wells (i.e., Santa Rosa and Nevárez) and one surface water source ((i.e., the 

super aqueduct) contributing to a blended system that serves a population of 31,061 people [Ref. 10, pp. 2−4, 32, 38, 

96]. The super aqueduct contributes greater than 70% of the total system production, and the active Santa Rosa and 

Nevarez wells contribute less than 15% each [Ref. 10, pp. 32, 38]. The apportioned populations and levels of 

contamination are presented below:

TABLE 9. TARGETS – GROUND WATER PATHWAY

Well Distance 

from Source 

(mi.)*

Population Level I 

Conc. 

(Y/N)**

Level II 

Conc. 

(Y/N)**

Potential 

Contam. 

(Y/N)

Reference(s)

Maguayo 2 1.5 9,157.5 Y Y N 10, pp. 4, 32

Maguayo 3 1.3 0 – inactive Y Y N 10, pp. 4, 32

Maguayo 4 0.9 0 – inactive Y Y N 10, pp. 4, 32

Maguayo 5 0.6 0 – inactive Y Y N 10, pp. 4, 32

Maguayo 6 0.1 9,157.5 Y Y N 10, pp. 4, 32

Maguayo 7 0.1 9,157.5 Y Y N 10, pp. 4, 32

Nevárez 1.0 4,538.01 N Y N 10, pp. 4, 38

Santa Rosa 0.9 4,643.62 N Y N 10, pp. 4, 38

San Antonio 3 1.1 0 – inactive N Y N 10, pp. 4, 38

Water bottling

plant

0.4 N/A – purified, 

packaged water and ice

Y Y N 10, pp. 4, 96–97

* Distance is measured from the approximate center of the area of observed ground water contamination (see Figure 

1). 

** See Table 6 for analytical results by ground water sample; see Table 5 for sample locations/well names by 

sample ID. Maximum Contaminant Level Goals (MCLG) greater than 0, Maximum Contaminant Levels (MCL), 

Cancer Risk Screening Concentrations (CRSC), and Noncancer Risk Screening Concentrations (NRSC) are used as 

benchmarks to evaluate the level of contamination for the ground water migration pathway [Refs. 1, p. 51593, 

Section 2.5.2; 2, pp. 1−5].

Applicable benchmarks for the hazardous substances detected in the observed release are as follows (benchmarks 

are presented in μg/L for consistency with reported data; boldface type denotes the lowest applicable benchmark 

concentration for each hazardous substance):

TABLE 10. HRS BENCHMARKS – GROUND WATER PATHWAY

Substance MCLG (μg/L) MCL (μg/L) CRSC (μg/L) NRSC (μg/L) Reference(s)

Bromodichloromethane --- --- 1.0 300 2, p. 1

Chloroform --- --- 2.1 100 2, p. 2

cis-1,2-DCE 70 70 --- 30 2, p. 3

PCE --- 5 32 90 2, p. 4

TCE --- 5 1.0 7 2, p. 5

37
GW-Targets

TABLE 11. LEVEL I CONCENTRATIONS

Well Sample Substance Conc. 

(μg/L)

Benchmark 

(μg/L)

Reference(s)

Maguayo 2 DGWC-GW06/ 

BCJQ6

Bromodichloromethane 7.9 1.0 (CRSC) 2, pp. 1−2; 7, p. 6; 8, pp. 

19, 59; 51, pp. 3, 138

Maguayo 3 DGWC-GW10/ 

BCJR0

Chloroform 24 2.1 (CRSC) 2, p. 2; 7, p. 6; 8, pp. 27, 

62; 51, pp. 4, 212−213, 

225

Maguayo 4 DGWC-GW09/ 

BCJQ9

Chloroform 13 2.1 (CRSC) 2, pp. 2, 4; 7, p. 6; 8, pp. 

25−26, 61; 51, pp. 4, 

200−201

PCE 7.6 5 (MCL)

Maguayo 5 DGWC-GW12/ 

BCJR2

Chloroform 18 2.1 (CRSC) 2, pp. 2, 4; 7, p. 6; 8, pp. 

31−32, 63−64; 51, pp. 4, 

247−248

PCE 11 5 (MCL)

Maguayo 6 DGWC-GW05/ 

BCJQ5

Chloroform 11 2.1 (CRSC) 2, pp. 2, 4; 7, p. 6; 8, pp. 

17−18, 58; 51, pp. 3, 

124−125

PCE 5.0 5 (MCL)

Maguayo 7 DGWC-GW04/ 

BCJQ4

Chloroform 7.9 2.1 (CRSC) 2, p. 2; 7, p. 6; 8, pp. 15, 

57; 51, pp. 3, 112−113

Water 

bottling plant

DGWC-GW08/ 

BCJQ8

Chloroform 13 2.1 (CRSC) 2, p. 2; 7, p. 6; 8, pp. 23, 

60; 51, pp. 4, 188−189

TABLE 12. LEVEL II CONCENTRATIONS

Well Sample Substance Conc. 

(μg/L)

Benchmark 

(μg/L)

Reference(s)

Maguayo 2 DGWC-GW06/ 

BCJQ6

PCE 0.66 J- 5 (MCL) 2, p. 4; 7, p. 6; 8, pp. 3, 

19–20, 59; 51, pp. 3, 138

Maguayo 3 DGWC-GW10/ 

BCJR0

PCE 2.9 5 (MCL) 2, p. 4; 7, p. 6; 8, pp. 27–

28, 62; 51, pp. 3, 

212−213, 225

Maguayo 4 DGWC-GW09/ 

BCJQ9

Cis-1,2-DCE 1.3 30 (RDSC) 2, p. 3; 7, p. 6; 8, pp. 25, 

61; 51, pp. 4, 200−201

Maguayo 5 DGWC-GW12/ 

BCJR2

Cis-1,2-DCE 2.2 30 (RDSC) 2, pp. 3, 5; 7, p. 6; 8, pp. 

31, 63; 51, pp. 4, 

247−248

TCE 0.68 1.0 (CRSC)

Maguayo 6 DGWC-GW05/ 

BCJQ5

Cis-1,2-DCE 1.2 30 (RDSC) 2, pp. 3, 5; 7, p. 6; 8, pp. 

17, 58; 51, pp. 3, 

124−125

TCE 0.54 1.0 (CRSC)

Maguayo 7 DGWC-GW04/ 

BCJQ4

Cis-1,2-DCE 1.0 30 (RDSC) 2, pp. 3−5; 7, p. 6; 8, pp. 

15−16, 57; 51, pp. 3, 

112−113

PCE 3.8 5 (MCL)

TCE 0.50 1.0 (CRSC)

Nevárez DGWC-GW07/ 

BCJQ7

PCE 1.5 5 (MCL) 2, p. 4; 7, p. 6; 8, pp. 21–

22, 60; 51, pp. 4, 178

Santa Rosa DGWC-GW11/ 

BCJR1

Chloroform 1.9 2.1 (CRSC) 2, pp. 2, 4; 8, pp. 29−30, 

PCE 1.2 5 (MCL) 63; 51, pp. 4, 236−237

San Antonio 

3 

DGWC-GW03/ 

BCJQ3

TCE 0.91 1.0 (CRSC) 2, p. 5; 7, p. 6; 8, pp. 13, 

56; 51, pp. 3, 98

Water 

bottling plant

DGWC-GW08/ 

BCJQ8

Cis-1,2-DCE 1.1 30 (RDSC) 2, pp. 3−4; 7, p. 6; 8, pp. 

23−24, 60; 51, pp. 4, 

188−189

PCE 3.7 5 (MCL)

38
GW-Nearest Well/Population

==================================================================================

==================================================================================

==================================================================================

==================================================================================

3.3.1 Nearest Well

As identified in Section 3.3, the active drinking water wells Maguayo 2, Maguayo 6, and Maguayo 7 are subject to 

Level I concentrations. Therefore, a nearest well factor value of 50 is assigned [Ref. 1, pp. 51602, 51603].

Nearest Well Factor Value: 50

3.3.2 Population

3.3.2.2 Level I Concentrations

As identified in Section 3.3, three active drinking water wells (Maguayo 2, Maguayo 6, and Maguayo 7) are subject 

to Level I concentrations. The populations assigned to the wells are also explained in Section 3.3. 

TABLE 13. LEVEL I POPULATIONS

Level I Well Population Reference(s)

Maguayo 2 9,157.5 10, pp. 37−40, 96

Maguayo 6 9,157.5 10, pp. 37−40, 96

Maguayo 7 9,157.5 10, pp. 37−40, 96

Population Served by Level I Wells: 27,472.5 Level I Concentrations Factor Value: 274,725 

3.3.2.3 Level II Concentrations

As identified in Section 3.3, two active drinking water wells (Nevárez and Santa Rosa) are subject to Level II 

concentrations. The populations assigned to the wells are also explained in Section 3.3. 

TABLE 14. LEVEL II POPULATIONS

Level II Well Population Reference(s)

Nevárez 4,538.01 10, pp. 32. 38, 96

Santa Rosa 4,643.62 10, pp. 32. 38, 96

Population Served by Level II Wells: 9,181.63 Level II Concentrations Factor Value: 9,181.63

3.3.2.4 Potential Contamination

The aquifer being evaluated (i.e., the NCLAS upper aquifer) is the principal source of fresh ground water in Dorado 

and historically has been the principal source of public-supply and industrial water use in the region [Refs. 19, pp. 

1−5; 20, pp. 1−7; 21, pp. 11−18]. Although there is no known active ground water use for drinking water in Toa 

Baja or Toa Alta, the municipalities to the east and south of Dorado, respectively, there is ground water use for 

drinking water in the municipality of Vega Alta less than 4 miles to the west [Refs. 4, p. 1; 30, p. 157; 53, pp. 1−4, 

7, 10]. However, since Level I and Level II concentrations result in a maximum score of 100.00 for the ground 

water migration pathway, the Potential Contamination Factor Value was not scored.

Potential Contamination Factor Value: NS

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GW-Resources/Wellhead Protection Area

3.3.3 Resources

Since Level I and Level II concentrations result in a maximum score of 100.00 for the ground water migration 

pathway, the Resources Factor Value was not scored.

==================================================================================

Resources Factor Value: NS

3.3.4 Wellhead Protection Area

Since Level I and Level II concentrations result in a maximum score of 100.00 for the ground water migration 

pathway, the Wellhead Protection Area Factor Value was not scored.

==================================================================================

Wellhead Protection Area Factor Value: NS

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