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• V. Rationale for Well Sampling and Analysis <br /> The four groundwater monitoring wells were installed to ascertain the <br /> initial background groundwater conditions in the vicinity of the MSC operational <br /> area. The Dames and Moore work had identified background parameters prior t <br /> the use of the site for petroleum coke storage. <br /> The MSC industrial activities used the site for storage of petroleum coke <br /> and for a limited period of time, it was used for copper concentrate storage. <br /> These materials were temporarily stored on site prior to being loaded on ships for <br /> delivery overseas. The background information was to monitor the existing <br /> conditions prior to using the site for the storage use of these products. The initial <br /> background site assessment was a study to ascertain to an initial degree the <br /> parameters studied by Dames and Moore. Consequently, it is TRE's opinion <br /> that the constituents of interest for monitoring well sampling are for the petroleum <br /> coke and copper since these were the only materials stored by MSC in this area. <br /> VI. Monitoring Well Sampling Procedures <br /> The following procedures will be used to sample the four existing <br /> . monitoring wells. <br /> VI. 1. Monitoring Well Head Survey Check: <br /> All wells will checked to establish the casing elevations survey to mean <br /> sea level. This will allow for accurate depth to water measurements and <br /> groundwater gradient calculation and flow contour plot. <br /> VI. 2. Groundwater Monitoring Well Purging and Sampling: <br /> Each monitoring well will be purged using calculated well volumes based <br /> upon the depth to water in each casing. Depth to groundwater measurements <br /> will be made to the nearest one-one hundredth of one foot, and also checked for <br /> the presence of separate phase product, if any. The purge volume will be <br /> calculated and at least two purge volumes will be removed prior to sampling. <br /> The purge will remove stagnant water in the casing and sand pack. Purging will <br /> continue until the indicator parameters listed below are observed to stabilize <br /> within 10% of the U. S. EPA recommended tolerance. The ultimate number of <br /> purge volumes is well specific. The well sampler will keep field sheets of the <br /> each well purge. <br /> . As each purge volume is removed, measurements of pH, electrical <br /> conductivity dissolved oxygen, turbidity and temperature will be taken until these <br /> 6 <br />