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| MAUNABO AREA GROUND WATER CONTAMINATION | Maunabo, Puerto Rico | |
Site Location:
The Maunabo Area Ground Water Contamination site consists of a ground
water plume with no identified source(s) of contamination. It is
located in the municipality of Maunabo, Puerto Rico, in the southeastern
area of the island. The size of the plume of contamination has not been
determined as yet, but EPA is currently conducting work to better define
the nature and extent of the contamination.
Site History:
The Maunabo public water system consists of four ground water wells:
Maunabo 1, Maunabo 2 (Bordaleza), Maunabo 3 (Calzada), and Maunabo 4
(San Pedro). Maunabo 1 went into service in 2001, while the other wells
were in service prior to that time. Ground water samples collected by
the system's operator, the Puerto Rico Aqueduct and Sewer Authority
(PRASA), indicate that chlorinated solvents have been detected in
Maunabo 1 since March 2002. At that time, the Puerto Rico Department of
Health ordered PRASA to close the well because the concentration of one
of the solvents exceeded the federal Safe Drinking Water Maximum
Contaminant Level (MCL). However, PRASA opted to treat the ground water
with carbon filtration tanks at the wellhead rather than close the well
in order to meet water supply needs. Since then, the detections of
solvents in raw ground water samples from Maunabo 1 have exceeded the
MCL on numerous occasions. Samples taken after treatment, including
tap water samples collected along the distribution system down-line from
Maunabo 1, indicate that the treatment has not been effective.
Site Contamination/Contaminants:
The contaminants of concerns are industrial solvents, including
tetrachloroethene (PCE), trichloroethene (TCE), and
cis-1,2-dichloroethene (DCE). Of these, PCE has been detected above
federal MCLs in drinking water supplies.
Potential Impacts on Surrounding Community/Environment:
Ground water and distribution water samples collected by EPA in October
2005 confirm the presence of PCE and cis-1,2-DCE in Maunabo 1 and in
post-treatment samples along the distribution line. These most recent
results also indicate the presence of a related compound, 1,1-DCE, in
Maunabo 4, which may indicate the spreading of contamination.
The Maunabo Urbano water system serves a total population of
approximately 14,000 people apportioned equally among the four public
supply wells (i.e., 3,500 per well). Therefore, the contaminated wells
in this system, Maunabo 1 and 4, serve almost 7,000 people. Wellhead
Protection Areas are delineated for the public supply wells, so the
plume lies within a designated Wellhead Protection Area.
Response Activities (to date):
EPA is investigating the contamination at the wells, including efforts
to locate the source(s) of the contamination. In November, 2005, EPA
began sub-surface geological work to assist in this effort.
[The description 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. See 56 FR 5600, February 11, 1991, or subsequent FR notices.]
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can 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.