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^ ,'�..-'7"'�T _.a <br /> . _ -.: <br /> rt}-.^ <br /> ¢ _ 1 :. : .9`�" �^.+,r' .rti, 1 w 'F - u rL; -` -`'r. •t. <br /> 4 r Yps} _ 4I Vti hd t:, Ya s Ss a' E} r r 4q <br /> f-. <br /> y:& <br /> C <br />:40 <br /> 7 <br /> :1 <br /> i <br />...i <br /> 2� <br /> 4 <br /> underground storage tank and accessory pump unit. The EHD <br /> does not be l i.•ve that sufficient data exists to make a "no n <br /> contamination" finding. <br /> 1• ' In order to accomplish these tasks, EHD believes that the <br /> local direction of flow of the water in the aquifers should Y <br /> be determined. The only sure way to da this is to measure <br /> precisely the standing fluid level in three or more nearby <br /> locations and to calculate the slope of the water table. <br /> Figures 1, 2 and 3 show the slope of the underground water <br /> table on a regional basis; howevp.r, the data is not as <br /> complete in the local area as on most of the map. The EHD <br /> has required that this water table elope be d.etgrmined. They <br /> have also required that the water in the ori site water well <br /> be tested for contaminates and that its level be determined, <br /> 4 � If one knew that the water in this well were in continuous <br /> hydraulic contact with that which will be found in <br /> monitoring wells, then_ only two monitoring wells would be <br /> needed to determine the water table slope because this slope <br /> can be determined with 3 points. Inasmuch as this is not <br /> known, this repor-1, recommends that three ;aor_itoring wells be <br /> drilled as shown on Figure 4. Well No. 1 is located in a <br /> down-slope water flow direction. as deduced from the County <br /> maps and adjacent to Airport Way. Well No. 2 Trill be <br /> located within 10' of the end of the tank excavation, in a <br /> position where any leakage would likely be discovered. Well <br /> No. 3 will be located adjacent to Airport Way in a southerly <br /> direction; which possibly also could be the direction o; <br /> g the water level in the current <br /> water flow. If, upon testin <br /> water well, it is found that the level obtained fits the <br /> pattern of the three monitoring wells, then this data will <br /> also be utilized in determining the water table slope. <br /> Proposed Field Work <br /> Figure 5 is a type diagram for the proposed monitoring <br /> wells. Exact depths for each of the operations shown will <br /> not be known until the bore holes are drilled. <br /> A portable, truck mounted, hollow stem auger drilling unit. <br /> will be used. A 10 nominal size O.D. hole will be bored to <br /> an estimated 30' below ground level or whatever depth is <br /> needed to penetrate the water table at least 10' . 50 gallon <br /> drums with sealing covers will be on site for collection of <br /> all auger cuttings and any water bailed from the wells. The <br /> cuttings and any water collected will be disposed of in a <br /> proper manner after the operation is concluded, the disposal <br /> methods will be dependent upon levels of pollutants found. <br /> The wells will be cased with 4" screw--jointed PV% with the <br /> bottom 10' plus pre-perforated with .02" slots, blank nosed <br /> on bottom. The well bore around the perforated interval will <br /> be packed with # 3 sand or the equivalent as a filter <br /> medium. A 2'-4' bentonite clay plug will be placed above the <br /> perforations, in the 4" pipe-borehole annulus, to act as a <br /> 3 <br />