Case Studies of 1,4-Dioxane Releases, Treatment, and Drinking Water Contamination - Environmental Investigation and Remediation - page 385

FDEP and Manatee convened a community meeting, at which the responsible party asked resi-
dents for help identifying private well locations and agreed to test wells and pay for connection to
public water if impacts were detected (FDEP, 2004). Several iterations of sampling detected
solvents above MCLs in some domestic wells and irrigation wells, and affected residents were
provided with bottled water. Temporary county water hookups were provided to all 17 homes that
were not previously connected to the public supply. Some of the affected private wells were located
a signii cant distance from the delineated plume; hence, further investigation of the plume was
conducted (FDEP, 2004).
Comparisons of contaminant levels between private and monitoring well data sets are difi cult to
evaluate owing to the multiple aquifers in this geologic setting and the unknown construction details
for most of the private wells that have been tested. Because of these limitations, FDEP generally
does not rely on private well data for contamination delineation or remediation monitoring purposes
(FDEP, 2006).
Because the impacted private wells were located outside the established VOC plume boundaries,
as delineated by the responsible party's consultant, FDEP conducted an investigation to identify the
source(s) of contamination and to resample all monitoring wells (Cilek et al., 2004). FDEP collected
39 groundwater samples from the suri cial aquifer; most of the samples were collected near its base.
Direct-push groundwater grab samples were collected at locations adjacent to existing monitoring
wells, selected irrigation wells, and potential source areas (Cilek et al., 2004). The highest TCE
concentration reported in the initial site groundwater survey, 2050 μg/L, was a direct-push grab
sample retrieved near the eastern boundary of the facility (Cilek et al., 2004; FDEP, 2004).
FDEP's results indicated a larger chlorinated solvent groundwater plume with higher concentra-
tions of chlorinated solvents than that delineated by the responsible party's monitoring wells. For
example, a TCE concentration of 550 μg/L was reported in one well, whereas analysis of the nearby
grab groundwater sample collected nearby reported a TCE concentration of 29,000 μg/L (35,000 μg/L
in a duplicate sample). FDEP interprets this result to be indicative of DNAPL (dense, nonaqueous-
phase liquid) because the concentration is greater than 1% of TCE's solubility in water (Cilek et al.,
2004). No analyses for 1,4-dioxane were performed in FDEP's or the responsible party's 2004
investigations.
In May 2004, some Tallevast neighborhood residents reported that they had received soil exca-
vated from the former American Beryllium site to i ll in low spots on their properties. Others,
concerned that they might be breathing vapors from contaminated groundwater underneath their
homes, requested indoor air testing of their homes (FDOH, 2007). During public meetings held in
June and July 2004, residents expressed a variety of health concerns they believed American
Beryllium caused, including high rates of cancer, fertility problems, and illnesses that they attrib-
uted to exposures to dust and surface soils transferred from American Beryllium to resident yards
(FDOH, 2007). In June 2004, the FDEP and the responsible party's consultants tested neighbor-
hood surface soil for metals, VOCs, semi-VOCs, and hydrocarbons (FDOH, 2007). Although sev-
eral of the soil samples were found to contain elevated levels of arsenic, lead, and petroleum-related
organic compounds * (Cilek et al., 2004), concentrations were generally only slightly above stan-
dards, and no pattern of pervasive soil contamination was identii ed.
In the fall of 2004, FDOH and the Manatee County Health Department tested for 61 VOCs in the
indoor air of three homes and in the community center located adjacent to the American Beryllium
site. The indoor air-testing sites are located over the highest concentrations of TCE in groundwater.
Summa canisters were used to collect three 8-h samples at each location. FDOH mailed letters to
each indoor air-testing participant explaining chemical results obtained from their indoor air,
including copies of the laboratory results and information on each chemical found. At all of the four
locations tested, most of the 61 chemicals analyzed in indoor air were nondetect. FDOH enlisted the
* 1,4-Dioxane was not tested on soil samples, but because of its high volatility and low sorption, is commonly not found
in soil.