Laserfiche WebLink
Beacon Station No 1641 July 10 2003 <br /> Stockton California Preltmmary Results Report and Work Plan Addendum <br /> Additional monitoring wells are needed to complete lateral delineation of the dissolved <br /> petroleum hydrocarbon groundwater plume at shallow groundwater table In addition, <br /> monitoring wells are needed to confirm and laterally evaluate hydrocarbons detected in <br /> groundwater at the 130-foot interval It is proposed to install two additional monitoring <br /> wells (MW-9 and MW-10) to Iaterally delineate the shallow groundwater at the locations <br /> shown on Figure 3 In addition, it is proposed to install an additional three monitoring wells <br /> (MW-11, MW-12, and MW-13) to confirm the presence of and evaluate the lateral extent of <br /> hydrocarbons in groundwater at 130 feet bsg at the locations shown on Figure 3 This data <br /> will be used for evaluating the soil profile and for development of a, plan for additional <br /> vertical delineation if necessary <br /> Lateral delineation of the groundwater plume to the west and south shall be provided by <br /> monitoring wells MW-9 and MW-10 with screened intervals at 35 to 55 feet bsg The <br /> vertical delineation of the groundwater plume in these directions has been demonstrated by <br /> the analytical results of groundwater samples collected from soil borings B-7 and B-8 <br /> Monitoring wells MW-11, MW-12 and MW-13 with screened intervals of approximately <br /> 130 to 135 feet bsg shall provide data to evaluate the presence of and the lateral extent of <br /> hydrocarbons reported in soil samples, and in the groundwater sample collected at 135 feet <br /> bsg from soil boring B-5 It is not recommended to attempt to vertically delineate further <br /> through directly beneath soil boring B-5 at this time This approach to confirming the data <br /> from soil boring B-5 is recommended to evaluate the potential lateral extent of hydrocarbons <br /> in groundwater in the 130-foot deep interval while decreasing the possibility of dragging <br /> hydrocarbons down from shallower hydrocarbon-impacted intervals via the drilling process <br /> The confirmation of hydrocarbons in monitoring wells MW-11, MW-12 and MW-13 shall <br /> provide data to evaluate the lateral extent of the groundwater plume at that depth and shall <br /> provide a basis for the necessity of further vertical investigation in the soil boring B-5 area <br /> If the data confirms lateral extent of hydrocarbons in the 135-foot deep interval, additional <br /> investigation into the vertical extent of the groundwater plume may be accomplished without <br /> WPaddnm7 03 <br /> Project No 1641 16 7 HORIZON ENVIRONMENTAL INC <br />