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Gealagual TecknccV 14C Page 3 Groundwater Monitoung Report Project No 724 2 January 17,2003 Figure 2 shows the location of the well pairs used for calculating vertical groundwater ' gradient in this report MW-4/MW-104, MW-6/MW-106, and MW-7/MW-107 Tables 1 & 2 show a Summary of Water Level and Gradients Slope and Bearing and Table 3 shows the calculated vertical gradients The information used in the calculations is shown below ' Verticala l rmu radient calculation f are as follows gformulas ' • vertical correction for gradient [(gw gradient slope) x (distance) = vertical correction] • vertical head [(head of deep well) - (head of shallow + correction) = vertical head] • vertical gradient [(vertical head) / (vertical distance) = vertical gradient] ' For the September 2002 event, the vertical gradient for the MW-4/MW-104 pair was negative (downward) In well pairs MW-6/MW-106 and MW-7/MW-107 the vertical gradient was positive (upward) These data are consistent with previous events The vertical distance to the deep well screen in the MW-4/MW-104 well pair is double the distance of the other two well pairs ' 1 2 Groundwater Sampling Procedure p 1; MOn September 12, 2002, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells and measured the depth to water with an electrically actuated sounding tape The ' water level reading was recorded to an accuracy of 0 01 foot In wells where free-floating product is suspected, a clear disposable bailer is used to gauge the interface No free- floating product was observed during this monitoring event ' Stagnant water in the well casing was purged using a dedicated Wattera pump as recorded in the field logs (Appendix C) The rate of well purging was monitored The wells were ' purged of at least three casing volumes until the groundwater parameters (temperature, conductivity, and pH) had stabilized (Appendix C) This indicated that water representative of actual aquifer conditions was entering the well Groundwater parameter stabilization was ' characterized by three successive readings within 10% Before a sample was collected, the water level was allowed to recharge to at least 80% of ' the initial level All water removed from the monitoring well and not used as a sample was placed in a properly labeled 55-gallon DOT (Department of Transportation 17-H) approved container and is temporarily stored on-site A dedicated Wattera pump was used to collect each sample Care was exercised while collecting samples to prevent agitation of the water contained in the bailer Water samples were transferred in a manner that minimizes sample aeration during transfer of the sample into 40-m1 VOA vials preserved with hydrochloric acid All