SITE INFORMATION AND CORRESPONDENCE

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Mr. Jim Thompson April 21 , 1986 Page Two We recommend that monitor wells number 11 , 12, 13,8 and "1 redrill" be plugged and abandoned in such a way that the gravel pack through the barrier zone be removed and cemented to reestablish the natural seal through that zone. It is unclear how the original number 1 monitor well was plugged. The chances are very good that the gravel pack in that well is still open through the barrier zone and that remedial work will have to be done on that well also. All other wells should be developed to the extent possible considering their construction. Then and only then can accurate water level data and water quality samples be collected. The monitor wells should also be surveyed so that ground water gradients can be determined and also the direction of slope on the top of the barrier zone. At this time we recommend that only monitor wells number 8 and number "l redrill" be replaced with properly designed, single zone completion monitor wells . Monitor well number 8 should be replaced because it is the only well to ever have floating product found in it. The reason for this is probably because the well was not drilled deep enough to establish a good drain into the lower water bearing formation. Also on the day it was electric logged there was 7 feet of fill in the bottom of the screen. Since the fill has migrated from the formation through the gravel pack to get inside the well screen, the chances are very high that the same fine grained fill has plugged the gravel pack in the bottom 7 feet of the well . The shallow depth of the well and the plugging in the bottom would combine to trap any hydrocarbon draining down from the perched zone and keep it in the well. Monitor well number 1 redrill should be replaced since it is the only deep well in that area of the site and is also nearest to the buried tanks. We propose chemical analyses be run on water samples from the upgraded monitor well network for Total Organic Carbon (TOC) , pH, Conductivity, Benzene, Toluene, Xylenes and Ethyl Benzene (Aromatics will be tested by GCMS) . At this time we plan on two sampling events about a month apart during which we will also take water levels to the nearest 1/100th of a foot and measure product thickness, if any. After the above tasks have been completed, a Groundwater Assessment Plan will be prepared which will also address, if necessary, the type of remedial action best suited to the site. This plan will be certified by a professional geologist and a California registered professional engineer. GMS & ASSOCIATES