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CLEAiK_ A'TER <br /> C R O U P <br /> Environmental Services <br /> GROUNDWATER MONITORING AND SAMPLING RESULTS <br /> Groundwater sampling results are summarized as follows <br /> Depth to groundwater range 9 08 (MW-2) to 1103 (MW-8) feet below <br /> top-of-casing (TOC) <br /> Flow direction and gradient Southeast at approximately 0 0046 ft/ft <br /> Benzene concentration range From not detectable (MW-2, MW-3, MW- <br /> 4) to 1,300 µg/L (MW-5B) <br /> Ethylbenzene concentration range From not detectable (MW-1, MW-2, MW- <br /> 3, MW-4, MW-8) to 300 L (MW-5B) <br /> TPH-g concentration range From not detectable (MW-2, MW-4) to <br /> 8,100 g/L (MW-5B) <br /> MTBE concentration range Not detected in concentrations exceeding <br /> indicated laboratory reporting limits <br /> The groundwater flow direction as determined by this sampling event is substantially the same as <br /> was determined by the previous monitoring event Groundwater elevation and analytical data are <br /> included in Table 1 A groundwater elevation map based on the groundwater elevation data <br /> from all monitoring wells was prepared and is enclosed as Figure 3 A revised iso-concentration <br /> map of benzene in groundwater is enclosed as Figure 4 Analytical reports for this groundwater <br /> sampling event are included as Attachment 3 <br /> SUMMARY AND CONCLUSIONS <br /> Results from this quarterly monitoring event appear to confirm results reported from previous <br /> groundwater monitoring activities, namely that the contaminant plume is currently delineated <br /> Contaminant concentrations appear to be highest in the MW-5B well <br /> PROJECT STATUS AND RECOMMENDATIONS <br /> Clearwater recommends continuation of groundwater monitoring events in wells MW-1 through <br /> MW-8 to confirm results reported herein and to determine contaminant concentration and <br /> distribution trends over the near future A dual-phase test well and air sparge point was installed <br /> at the site in February, 2002 Remedial feasibility testing at the site was conducted during the <br /> week of March 10, 2002 The Well Installation and Feasibility Testing Report was sent on May <br /> 9, 2002 <br /> • <br /> ZB778C 4 June 3, 2002 <br />