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Geofogcaf?echmcs Inc Page 3 <br />' Groundwater Momtonng Report <br /> Project No 724 2 <br /> • October 3,2002 <br /> Figure 2 shows the location of the well airs used for calculating vertical groundwater <br /> g p <br /> gradient in this report MW-4/MW-104, MW-6/MW-106, and MW-7/MW-107 Tables 1 & <br />' 2 show a Summary of Water Level and Gradients Slope and Bearing and Table 3 shows the <br /> calculated vertical gradients The information used in the calculations is shown below <br /> Vertical gradient calculation formulas are as follows <br /> • vertical correction for gradient [(gw gradient slope) x (distance) —vertical correction] <br /> • vertical head [(head of deep well) - (head of shallow + correction) =vertical head] <br /> • vertical gradient [(vertical head) / (vertical distance) =vertical gradient] <br />' For the June 2002 event, the vertical gradient for the MW-4/MW-104 pair was negative <br /> (downward) In well pairs MW-6/MW-106 and MW-7/MW-107 the vertical gradient was <br />' positive (upward) These data are consistent with previous events The vertical distance to <br /> the deep well screen in the MW-4/MW-104 well pair is double the distance of the other two <br /> well pairs This may explain the anomaly for the differing gradients <br />' 1.2 Groundwater Sampling Procedure <br /> On June 21, 2002, Del-Tech Geotechnical Support personnel arrived on-site, opened the <br /> wells and measured the depth to water with an electrically actuated sounding tape The <br /> water level reading was recorded to an accuracy of 0 01 foot In wells where free-floating <br />' product is suspected, a clear disposable bailer is used to gauge the interface No free- <br /> floating product was observed during this monitoring event <br /> Stagnant water in the well casing was purged using a dedicated Wattera pump as recorded <br /> in the field logs (Appendix C) The rate of well purging was monitored The wells were <br /> purged of at least three casing volumes until the groundwater parameters (temperature, <br />' conductivity, and pH) had stabilized (Appendix C) This indicated that water representative <br /> of actual aquifer conditions was entering the well Groundwater parameter stabilization was <br />' characterized by three successive readings within 10% <br /> Before a sample was collected, the water level was allowed to recharge to at least 80% of <br /> the initial level All water removed from the monitoring well and not used as a sample was <br /> placed in a properly labeled 55-gallon DOT (Department of Transportation 17-H) approved <br /> container and is temporarily stored on-site <br /> A dedicated Wattera pump was used to collect each sample <br /> Care was exercised while collecting samples to prevent agitation of the water contained in <br /> the bailer Water samples were transferred in a manner that minimizes sample aeration <br /> during transfer of the sample into 40-m1 VOA vials preserved with hydrochloric acid All <br /> r <br />