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The Vieques Project > Potential Contaminant Sources & Site-Related Contamination > SWMU & AOC

Site-Related Contamination

Solid Waste Management Units (SWMU) and Areas of Concern (AOC)

Surface water, sediment, groundwater, and soil samples were collected during several environmental investigations of the western and eastern sides of the island (Table 2).   Metals have been detected in groundwater samples from all of the AOCs and SWMUs; pesticides at a few of the AOCs and SWMUs; and polychlorinated biphenyls (PCBs) at one of the SWMUs.  Metals have been detected in sediment and surface water samples from the AOCs and SWMUs where samples have been collected. Metals have been detected in most of the soil samples collected from the AOCs and SWMUs.  Pesticides and polycyclic aromatic hydrocarbons (PAHs) have been detected in soil collected from several of the AOCs and SWMUs.  At this time, metals are the primary contaminants of concern to NOAA at the AFWTA site.

The maximum contaminant concentrations detected during the preliminary assessment/site investigations of the western side of Vieques Island are summarized and compared to relevant screening guidelines in Tables 3, 4, and 5.  The results of the preliminary assessment/site investigations were used by the U.S. Navy and the USEPA to guide further investigations at the AOCs and SWMUs on the western side of Vieques Island .  The results of these further investigations are not finalized at this time therefore; they are not included in the discussion below.

Site-specific or regionally specific screening guidelines are always used when available.  In the absence of such guidance, the screening guidelines for groundwater and surface water are the ambient water quality criteria (AWQC) (USEPA 2002); the screening guidelines for sediment in a saltwater environment are the effects range-low (ERL) concentrations (Long et al. 1998); and the screening guidelines for soil are the Oak Ridge National Laboratory final preliminary remediation goals (ORNL-PRGs) (Efroymson et al. 1997) and the USEPA's ecological soil screening guidelines (USEPA 2004b).  Maximum concentrations that exceeded relevant screening guidelines are discussed below. When known, the general sampling location of a sample that exceeded screening guidelines is also provided.

Surface Water

Metals were detected in surface water collected from the site at maximum concentrations that exceeded the AWQC (Table 4).  The maximum concentrations of arsenic, cadmium, chromium, copper, lead, mercury, selenium, silver, and vanadium were detected at SWMU 6.  The maximum concentrations of nickel and thallium were detected in samples collected from AOCJ.  The maximum concentration of mercury exceeded the AWQC by one order of magnitude.  The maximum concentration of silver exceeded the AWQC by a factor of approximately four.  The maximum concentration of lead exceeded the AWQC by a factor of approximately two, while the maximum concentration of copper exceeded the AWQC by a factor of approximately 1.5.

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Groundwater

Metals and pesticides were detected in groundwater samples collected from the site at maximum concentrations that exceeded screening guidelines (Table 4).  The maximum concentrations of cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, vanadium, and zinc were detected in a sample collected from a monitoring well at SWMU 4 on the western side of Vieques Island .  The maximum concentration of arsenic was detected at SWMU 7 on the western side of the island.  The maximum concentration of copper exceeded the AWQC by four orders of magnitude.  The maximum concentrations of lead, nickel, silver, and zinc exceeded the AWQC by two orders of magnitude.  The maximum concentrations of chromium and selenium exceeded the AWQC by one order of magnitude.  The maximum concentrations of mercury exceeded the AWQC by a factor of three.  No AWQC is available for comparison to the maximum concentration of vanadium. 

The pesticides 4,4'-DDT and dieldrin were detected in samples from the main operations area on the western side of Vieques Island at maximum concentrations that exceeded the AWQC by one order of magnitude.  PCB Aroclors 1221 and 1232 were detected in samples collected at SWMU 6 on the western side of the island at maximum concentrations that exceeded the AWQC by one order of magnitude and a factor of three, respectively.

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