|
Geosyntec
<br /> consultants
<br /> • In July 2020, the Port collected grab-groundwater samples at two locations at Site 3
<br /> and four locations in the Central Area to evaluate the extent of the VOC plumes.
<br /> • In July 2020, the Port installed three new monitoring wells at Site 3 (W-337, W-338,
<br /> and W-339), four new monitoring wells at Site 4 (W-331, W-332, W-333, and
<br /> W-334), and four new monitoring wells in the Central Area(W-335, W-336, W-340,
<br /> and W-341)to monitor the groundwater plumes.
<br /> • In February 2021, the Port conducted well locating activities using a surveyor to mark
<br /> historical well coordinates and use hand tools to unearth wells that had been buried.
<br /> Of the 162 wells previously unable to be located based on visual inspection during the
<br /> 2018 to 2020 groundwater monitoring events, 124 were located(Geosyntec, 2021b).
<br /> 1.4 COCs in Groundwater
<br /> The Site investigation work, including the review of records on historical uses, and the sampling
<br /> conducted by the Navy between 1984 and 2002, was the basis for the site-specific contaminants
<br /> listed in Exhibit A of the Consent Agreement(State of California, 2003). The list provided in
<br /> Exhibit A of the Consent Agreement is not media-specific and does not identify if the CDCs are
<br /> in soil, soil gas, groundwater, surface water, or sediment. COCs listed in Exhibit A of the
<br /> Consent Agreement for one or more sites include VOCs, TPH, metals,pesticides, DDT, dioxins,
<br /> furans, SVOCs, PCBs, PAHs, debris, and radium (State of California, 2003).
<br /> The 2022 groundwater monitoring program is based on previous evaluations of potential COCs
<br /> in groundwater at RRI (Tetra Tech, 2002; Environmental Risk Services Corporation [ERS],
<br /> 2012a; ERS, 2012b; ERS, 2012c; ERS, 2012d; Geosyntec, 2018a; Geosyntec, 2020b; Geosyntec,
<br /> 2020c; Geosyntec, 2020d; Geosyntec, 2021b). Based on historical data and evaluations done by
<br /> the Navy and the Port, VOCs, in particular chlorinated solvents, are the primary COCs detected
<br /> in groundwater at RRI (Tetra Tech, 2002; ERS, 2015; Geosyntec, 2018a; Geosyntec, 2020b;
<br /> Geosyntec, 2020c; Geosyntec, 2020d; Geosyntec, 2021b).
<br /> The following VOCs were detected above the Maximum Contaminant Levels (MCLS) and/or the
<br /> DTSC Tap Water screening levels at one or more wells at RRI at least once between 2018 and
<br /> 2021 (Appendix B):
<br /> • Tetrachloroethene (PCE)
<br /> • Trichloroethene (TCE)
<br /> • Cis-1,2-dichloroethene (cis-1,2-DCE)
<br /> • Trans-1,2-dichloroethene (trans-1,2-DCE)
<br /> • Vinyl chloride (VC)
<br /> • 1,1,2,2-Tetrachloroethane
<br /> •
<br /> 1,1-Dichloroethane (1,1-DCA)
<br /> • 1,2-Dichloroethane (1,2-DCA)
<br /> • Benzene
<br /> RRI Groundwater Monitoring Work Plan 5 June 2022
<br />
|