OSWER/OSRTI Washington, DC 20460


## N ATIONAL 

## P RIORITIES 

## L IST 

## (NPL)

[The descri ption of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change as additional information is gathered on the sources and extent of contamination.]

For more information about the haz ardous substances identified in this narrative summary, including general information regarding the effects of exposure to th ese substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs ca n be found on the Internet

at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1

- 888

- 42

- ATSDR or 1

- 888

- 422

- 8737. *** Final Site*** March 2011 

### HORMIGAS GROUND WATER PLUME Ca guas , Puerto Rico

 **Site Location :**  The Hormigas Ground W ater Plume sit e , which consists of a ground water plume with no identified source(s) of contamination

, is located i n the municipality of Ca guas , in interior east

- central Puerto Rico

.

 **Site History:** The former Hormigas public water system (PWSID 5426) consisted of two wells (Eufracia and Hormigas) and served a population of 5,488 people. In August 2006, t he system’s operator, Puerto Rico Aqueduct and Sewer Authority (PRASA), detected tetrachloroethene (PCE) above EPA’s Safe Drinking Water Act M aximum C ontaminant L evel s (MCL s ) in the Eufracia well. In response, the Commonwealth issued Notices of Violation in November 2007 and an Administrative Order in February 2008. PRASA closed t he Hormigas water system and disconnected the wells in February 200 9

. EPA collected two ground water samples from the Eufracia well in August 2009, and the results confirmed the presence of PCE. Trichloroethene (TCE) and cis

- 1,2

- dichloroethene (cis

- 1,2

- DCE) were also detected in the Eufracia well

.

 **Site Contamination/Contaminants:** Chlorinated solvents (i.e., PCE , TCE, and cis

- 1,2

- DCE ) are present in ground water

. The PCE and TCE concentra tions significantly exceed the MCL s

.

 **Potential Impacts on Surrounding Community/Environment :**  The Hormigas public water system , which provided water to more than 5,000 persons for many years , is no longer operational

. S everal community supply wells loca ted within approximately 1 mile of the plume could suffer future impacts.

 **Response Activities (to date):**
The Commonwealth issued Notices of Violation to PRASA in November 2007 and an Administrative Order in February 2008. The Hormigas water system was closed in February 2009. In December 2009, EPA conducted a reconnaissance effort in the vicinity of the Hormigas and Eufracia wells as part of a Site Discovery Initiative to identify po ssible sources of contamination

. In February 2010, EPA collected soil samples from seven facilities identified as po ssible sources

. Although PCE was detected in one soil sample, there is not sufficient evidence to identify the source of ground water contamination

.

 **Need for NPL Listing:** Other federal and state cleanup pr ograms were evaluated, but are not viable at this time. EPA received a letter of support for placing this site on the NPL from the Commonwealth of Puerto Rico.