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90343TEXT CON-4 <br /> The sample analyses were performed by Multi-Tech Laboratories in Santa <br /> Rosa, California. All samples were analyzed for total petroleum <br /> hydrocarbons using a gas chromatograph with flame ionization detection <br /> (GC/FID) . The results of the analyses are discussed later in this report. <br /> Monitoring Well Installation <br /> Following completion of each boring a four inch PVC monitoring well was <br /> installed to an approximate depth of 20 ft. In general the wells were <br /> constructed of five feet of blank casing followed by 15 ft of factory <br /> slotted (0.030 slot) casing. A #3 sand well pack extended from completion <br /> depth (20 ft) to approximately 1.5 ft above the top of the screen (3.0 to <br /> 3.5 ft below grade) followed by 1.0 to 2.0 ft of bentonite. The remainder <br /> of the annulus was filled in with a concrete-bentonite mixture. Traffic <br /> rated Christy boxes were used to complete the wells at the surface. <br /> Individual well construction details are given in the boring logs appended <br /> to this report. <br /> During installation, some problems were encountered with flowing sands <br /> entering the boring before the casing could be installed. In most cases <br /> the problem could be alleviated somewhat by cleaning out the boring as much <br /> as possible before pulling the augers and inserting the casing. Flowing <br /> sands were especially a problem in Boring 2 and because it is within the <br /> spill area and may also be used as an extraction well , the original boring <br /> was redrilled five feet to the north with the larger 10 inch augers. <br /> Although considerably slower, this enabled the well casing and sand pack to <br /> be installed down the hollow stem prior to pulling the augers. The <br /> original boring was abandoned by backfilling it with a mixture of native <br /> materials and bentonite to within three feet of surface. This was followed <br /> by two feet of bentonite and one foot of concrete. <br /> Well Development, Monitoring and Sampling <br /> On August 12 a return visit was made to the site to take the initial <br /> fluid level measurements and develop the new wells. Level measurements <br /> were first taken in the new wells (MW-13 through MW-16) and selected <br />