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1 ' <br /> I <br /> i <br /> Two additional monitoring wells are proposed to characterize the northern and <br /> northeast extent of the plume. These locations are labeled in Appendix VIII. <br /> Parker Environmental Service has documented that the gradient is changing, but <br /> they suspect that the groundwater gradient appears flat, and there will be little <br /> movement or direction change of the plume. The existing and new proposed <br /> monitoring wells should define the lateral extent of the groundwater plume. <br /> I Bacteria added to the monitoring wells should move in the same directions of the ✓ <br /> gradient and should remediate any petroleum products found in the groundwater. <br /> If monitoring well information indicates that the groundwater plume did not <br /> originate from the tank excavation area, all construction of additional <br /> monitoring wells or remediation of the groundwater will cease. Monitoring wells <br /> will then be constructed to determine the new location of the contaminants and <br /> this information will be detailed in the Site Assessment Report. <br /> 8. 0 UINF I RMAT I ON SAMPLING <br /> Once the groundwater and soil plumes have been defined, remediation will continue <br />! until preliminary sampling results indicate that the contaminant levels are ate✓ <br /> non detect. Confirmation sampling will then begin to confirm that all <br /> contaminations in the soil plume and the groundwater plume have been remediated. <br /> Confirmation sampling will consist of analyzing water and soil for Total <br /> Petroleum Hydrocarbons as gasoline, and for benzene, toluene, ethyl benzene, and <br /> xylene (BTEX). If water and soil samples are non detect, this will confirm that <br /> I� the soil and water plumes are remediated. <br /> Water samples will be taken from all monitoring wells. Two consecutive water <br /> samples taken 30 days apart will confirm that this monitoring well is clean. <br /> Clean confirmation samples from all existing monitoring wells will confirm that <br /> the groundwater plume has been remediated. <br /> 1 <br /> The soil sampling locations will be determined by a grid method. The grid will <br /> be made up of one foot squares located within the soil plume boundaries. Squares <br /> will be selected by random numbering. Core samples will be taken from the center <br /> of each selected square and analyzed for TPH-Cs and BTEX. Twenty percent of the <br /> squares will be sampled. / <br /> 1 ✓/ <br /> Any squares with a non detect result will be certified clean. Squares with <br /> sample results above non detect will be retreated and then resampled until they <br /> are non detect. <br /> I <br /> w 4 <br />