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Cie0bgkat 7echmcs Inc Page 4 ' Groundwater Monitonng Report Project No 723 2 June 21, 2006 ' The following procedure is used to calculate vertical groundwater gradient ❑ Determine vertical distance between the two measuring devices by the distance from the ' mid-point between the top and bottom seal of the deep well (MW-201) and the mid-point between the groundwater elevation and the bottom seal in the shallow well (MW-3) ❑ Measure the head in both wells used in the calculations ' ❑ If the lateral distance between the well pair is greater than a few feet, then calculations must be made to correct the down-gradient piezometric head to account for the sloping water table between the wells The calculation considers the slope of the water table and the distance in a down-gradient direction between the two wells used in the calculations Figure 2 shows the location of the well pairs used for calculating vertical groundwater ' gradient in this report MW-3/MW-201, MW-8/MW-108 and MW-108/MW-208 Tables 1 - 4 show Summaries of Water Level and Gradients SIope and Bearing and Table 6 shows the ' calculated vertical gradients The information used in the calculations is shown below Vertical gradient calculation formulas are as follows ' ❑ Vertical correction for gradient [(groundwater 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 2"d Quarter 2006 event ' o The vertical gradient for the MW-3/MW-201 pair was zero (or no vertical flow) at 0 00 ft/ft o The vertical gradient for the MW-8/MW-108 pair was positive (or upward) at 0 007 ft/ft o The vertical gradient for the MW-108/MW-208 pair was negative (or downward) at 0 002 ft/ft ' o Previous calculations have revealed both positive and negative gradients at the site but additional monitoring is needed to determine long-term trends especially in the CMTTM well sets 1.2 Groundwater Sampling Procedure P la On April 17, 2006, 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 readings were recorded to an accuracy of 0 01 feet In wells where free-floating product is suspected, a clear disposable bailer is used to gauge the interface No free product was noted during this event (this procedure is not exercised in the CMT'fm wells due to their limited diameter) However, product "sheen" was noted in well MW-3 by the field technician r