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1 <br /> . 3.0 CONCLUSIONS AND RECOMMENDATIONS <br /> Groundwater levels have risen an average of 0 95 feet since groundwater levels were last <br /> measured on November 5, 1998 The groundwater gradient was calculated at 0 005 foot/foot in a <br /> northeasterly direction <br /> i Concentrations of TPH-as-diesel, TPH-as-gasoline, BTEX and MTBE were not detected in any of <br /> the three monitoring wells Since relatively high concentrations of diesel hydrocarbons were <br /> previously observed in close proximity to the former USTs, contaminant migration appears to be <br /> limited and probably stable <br /> i Based on these results and on consultation with PHSIEHD, Ramage Environmental recommends <br /> that quarterly groundwater monitoring be suspended and that the following course of environmental <br />! corrective action be implemented <br /> 1 Prepare a mass balance calculation to estimate the volume of residual petroleum hydrocarbons <br /> in the vicinity of the former USTs <br /> • 2 Evaluate the potential threat of residual petroleum hydrocarbons on groundwater quality and <br />! human health and the environment <br />! 3 Based on these evaluations, prepare a request for site closure or develop a revised plan of <br /> environmental corrective action <br />! <br /> i <br /> i <br /> i <br /> i <br /> i <br />