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U01 <br /> IN=19 <br /> c M <br /> rr.. The WJH report, Plate V, indica'-.ed the regional groundwater <br /> gradient to be dipping to the northwest:. <br /> Figure 2, groundwater levels, Spring 1990, show the same <br /> trend and indicate present groundwater levels to be about <br /> 26' below ground level (estimating ground level to be 39' <br /> MSL, minus water table at 13' MSL) . Figure 3, the map for <br /> water levels in the fall of 1983, shows the highest water <br /> level during recent years to have been about 15 ' below <br /> ground level (estimating ground level to be 39'M5L, minus <br /> water table at 24' MSL) . <br /> PROPOSED WORK <br /> A safety operations plan for the drilling, sampling and well <br /> { construction operations is to be supplied by the contractor. <br /> t <br /> Figure 4 is a site map showing the locations of the property <br /> and the .various features discussed. This map, as those in <br /> the WJH Site Assessment Report, were not surveyed but are <br /> believed to be sufficiently accurate fo_ the purposes of <br /> this report. The monitoring wells, when, drilled, will be <br /> accurately located on a site map and the relative eleva- <br /> tions of the well heads will be established so that an <br /> accurate water table slope can bo established. <br /> Proposed Monitoring Well # 1 is located ad,jacer.c to the site <br /> E" from which the contaminated soil was removed and in the <br /> direction of- probable water flow. Wells # 2 and # 3 will be <br /> located about 7.40'-15o' southerly and westerly of # 1. These <br /> 1 locations were chosen so that all three wells would be on <br /> Raymond Investment property. If water contamination is found <br /> r at the # 1 well site, then at least one more well will be . <br /> a necessary in a down-flow direction., <br /> mined from the three wells. <br /> which will be deter- <br /> Figure 5 is a t <br /> _�. ype diagram for the proposed monitoring <br /> wells. A 7"-8" O.D. nominal size, hollow stem auger hole <br /> will be bored to approximately 40' below ground level, or to <br /> at least 1C feet into the water table, wherever it is <br /> located. Truck mounted equipment will be used. 50 <br /> gallon <br /> drums with sealing covers will be on site to collect auger <br /> a cuttings: and water if the wells are bailed and samples <br /> collected prior to cementing pipe in the hole. The solid <br /> materials will be stored on site with the excavation spoil <br /> 1' and will be properly disposed of after the operation is <br /> w <br /> a completed. The water will be disposed of in the sewer if <br /> permission is granted by the City of Manteca. The wells will <br /> be cased with 411, screw jointed FVC with the bottom io' <br /> perforated with .02" Slots and the surrounding well bore <br /> packed_with-#- 3-sand--or-equivalent -as--a-filter. A-Z; to-5 ----- -------: T T,T -- <br /> bentonite clay plug w311 be. placed above the perforations as <br /> a protection from cementing operations. The upper 25.1 plus <br /> or minus annulus between the bore hole .and the well .casing <br /> 2 <br /> J, <br />