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" Y�Y E�JLi- 1386 E BEAMER STREET <br /> WOODLAND CA 95695 9603 <br /> WESTERN GEQ-ENGINEERS rAX (916)662 0273 <br /> CALIF CONTRACTOR s 513857 A CORPORATION (9 1 6) 662-454 i <br /> y September 26,1990 RED GEOLOGISTS <br /> a <br /> Mr. John Margowski <br /> Wickland Properties <br /> 1765 Challenge Way <br /> Sacramento, Ca. 95814 <br /> (916) 921-1100 <br /> RE: Update Assessment and Status Report #4 with work plan for a <br /> vapor recovery pilot test and the installation of the necessary <br /> wells and manifold system at former Regal Station 604, located a <br /> 1448 N. El Dorado Street, Stockton, California. <br /> Dear Mr. Margowski: <br /> The following is the update of events that have occurred at this <br /> site since Update Status Report dated, May 31, 1990. <br /> Western Geo-Engineers (WEGE) installed two ground water monitoring <br /> wells on site. Monitor well MW5 was installed at 21 degrees off <br /> of vertical in a southwest direction under the store and monitor <br /> well MW6 was installed in the planter at the intersection of <br /> Larding and El Dorado, see Appendix A. The pump dispensing area <br /> has been demolished and contaminated soil beneath the dispensers <br /> has been excavated to the 13 foot depth at the center dispenser <br /> and the 20 foot depths at the eastern and western dispensers. The <br /> eastern and western excavations were back filled with 1/40 clean <br /> pea gravel to the ,.calve foot depth. Immediately after the <br /> completion of excavating each excavation was sampled. The tank <br /> excavation was over excavated to the 25 foot depth, sampled and <br /> then back filled with 1/4" pea gravel to the 12 foot depth and <br /> compacted native soil to the 3 foot depth, see Figures 3, 3B, 3C <br /> and Table 1. <br /> Also a ground water monitoring round was conducted on August 24, <br /> 1990, and aeration of the excavated soil has been ongoing, see <br /> Appendix C-AERATION LOGS. <br /> GROUND WATER MONITORING <br /> A ground water monitoring round was conducted on August. 24, 1990. <br /> During this visit, depth to ground water was measured and samples <br /> were obtained from the six on site monitor wells for chemical <br /> analysis. From this data, a ground water gradient map was <br /> generated, Figure 4E. The increase in gradient from the <br /> previously exisiting wells (MW1, MW2, MW3 and MW4) towards monitor <br /> well MW6 indicates that MW6 had not stabilized since its <br /> development on August 16, 1990. A comparison was made to <br /> previously generated ground water gradient maps, Figures 4A thru <br /> 4D. Evident from the comparisons of these figures are variations <br /> 1 <br />