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1 ' <br /> Geological Technics htc. Page 2 <br /> Groundwater Monitoring Report <br /> Project No. 1030.2 <br /> April 19,2004 <br /> ' <br /> casing. The average groundwater elevation for the <br /> January 2004 event was 63.89 feet <br /> above mean sea level (MSL). Site-specific groundwater bearing and slope were calculated <br /> ' and found to be N45°E @ 0.0031 ft/ft. These results are consistent with historical <br /> groundwater bearing and slope for this site. <br /> ' Groundwater elevation decreased 0.26 feet since the October 2003 monitoring event. This <br /> decrease in groundwater elevation corresponds with seasonally groundwater fluctuations <br /> ' recorded at this site. Fields, north and east of the site, are flood irrigated during the growing <br /> season and may explain the seasonal fluctuations. <br /> ' Vertical groundwater gradients were calculated for the site using the MW-1/MW-101 well <br /> pair and found to be negative. This is the second time a negative vertical gradient has been <br /> recorded at the site. The site-specific vertical groundwater gradient is -0.0037 ft/ft. MW-1 <br /> is screened from 5 to 20 feet bgs and MW-101 is screened from 29.5 to 34.5 feet bgs. <br /> Vertical groundwater gradient calculations have been performed at regular intervals since <br /> the installation of MW-101 on April 12, 2002. The vertical groundwater gradient calculated <br /> ' for the January 2004 monitoring event mirrored the calculated horizontal groundwater <br /> gradient. The historical vertical gradients have been positive and approximately one order <br /> of magnitude less than the horizontal gradients. <br /> Groundwater elevation, bearing and slope were calculated using data gathered from MW-2, <br /> MW-3 and MW-4 during the January 23, 2004, monitoring event and the results are <br /> ' summarized in Table 1 of Appendix A. Table 2 of Appendix A summarizes the vertical <br /> groundwater gradient calculations. <br /> ' 1.2 Groundwater Sampling Procedure <br /> ' On January 23, 2004, Del-Tech Geotechnical Support Service personnel arrived on-site, <br /> opened the wells and measured the depth to water with an electrically actuated sounding <br /> tape. The water level reading was recorded to an accuracy of 0.01 foot. If free floating <br /> ' product had been suspected, a clear disposable bailer would have been used to gauge the <br /> interface. No floating product was observed during this sampling event. <br /> ' Stagnant water in the well casing was purged using a Waterra© pump and dedicated tubing. <br /> The rate of well purging was monitored. The well was purged of at least three casing <br /> volumes until the groundwater parameters (temperature, conductivity and pH) had stabilized <br /> (Appendix C) indicating that water representative of actual aquifer conditions was entering <br /> the well. Groundwater parameter stabilization was characterized by three successive <br /> ' readings within 10%. <br /> Before a sample was collected from each well, the water level was allowed to recharge to at <br /> least 80% of its initial level. MW-5 exhibited very slow recharge and was sampled at 70% <br /> 1 <br />