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# Comment Response to Comment <br /> deeper vinyl chloride plume. The maximum extent of the plume <br /> is unknown to the east, south, and west. The proposed grab <br /> groundwater samples GGW-11 and GGW-12 will be able to <br /> delineate the plume to the north. <br /> Recommended Actions: Central Valley Water Board staff <br /> recommend the Port advance additional grab groundwater <br /> samples surrounding the plume detected at well W-302 to <br /> delineate the maximum horizontal and vertical extent of <br /> contamination. <br /> 7 Issues: The plume boundaries drawn on Figure 7 of the 14 See response to DTSC General Comment 3h. P-140 is located <br /> December 2018 Constituents of Concern Evaluation Report are upgradient of the groundwater plume. <br /> inferred(dashed)to the east and west of the Southern Landfills <br /> area. However,the Port does not propose to advance grab <br /> groundwater samples to the east or west of the Southern <br /> Landfills to constrain the plumes in the Investigation. <br /> Recommended Actions: Central Valley Water Board staff <br /> recommend the Port add additional grab groundwater samples <br /> to define the maximum horizontal and vertical extent of the <br /> Southern Landfill plumes to the east(e.g.between P-138 and <br /> W-040 to the east and near P-140 to the west). Central Valley <br /> Water Board staff also recommend adding an additional grab <br /> groundwater sample near P-133 to define the maximum extent <br /> of plume migration to the northeast. <br /> 8 Issues: The plume boundaries drawn on Figure 8 of the 14 See response to DTSC General Comment 3g. <br /> December 2018 Constituents of Concern Evaluation Report are <br /> inferred (dashed) for almost the entire extent. The Port only <br /> proposes to investigate the southern area of this plume in the <br /> Investigation with the grab groundwater sample GGW-17. <br /> Additional samples are required to the north, east,and west. <br /> Existing wells such as W-204 and W-156 do not adequately <br /> define the vertical extent of the vinyl chloride plume. <br /> 8 08.03.2019 <br />