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AES Environmental, Inc. <br /> tj vlr. teff Werner <br /> Februr.ry 12, 1991 <br /> Page 5 <br /> I the results of the PID field screening and visual inspection of soil samples, perform <br /> chemical analyses on selected soil samples a;a state-certified chemical laboratory for Y <br /> W total petroleum hydrocarbons (TPH)as gasoline, benzene, toluene, ethylbenzene, and <br /> I xylenes using ]EPA Methods 801518020. At this time,it is anticipated that two soil <br /> samples will be submitted for chemical analysis; <br /> f� <br /> ! ' • Install 6-inch diameter PVC extraction well through the hollow stem of the augers. <br /> The well will be constructed to hay:screen adjacent to the saturated and recently <br /> unsaturated permeable portion of the borehole, blank using from the Vup o:the <br /> k screen to the ground surface, sand pack from the bast of the borehole to a height of <br /> one to two feet above the top of the screen, a bentonite seal above the sand pack:, and <br /> a neat cement annular seal to ground surface. The well will be completed below <br /> ox and be equipped with a locking rap or cover; <br /> grade in a traffic-rated christy b <br /> F"t • Survey the reference elevation relative to mean sea level arid the location for each <br /> r" monitoring and extraction well. <br /> the results of chemical analtises are obtained and <br /> Drsll cuttings will be stared onsite until <br /> I proper disposal is arranged. <br /> Subtask 313. Well Development and Sampling <br /> Prior to collecting groundwater samples from each well, the wells must be adequately <br /> developed to reduce the potential deleterious effects of drilling on the representativeness of <br /> Before developing or sampling any well, the pretence of floating <br /> grcandwater samples. <br /> product will be assessed by visual inspection of groundwater samples collected with a clear <br /> plastic bailer and/or by using an oillwater interface probe. Well development will be <br /> .t riormed using a combination of surgingiswabbing and bailing, by pumping, or both. <br /> j s Surging/swabbing sorts the sand pack and pumping removes fine sand and sediment from the <br /> I.t well. The pH, temperature, and electrical conductivity of the development water will be <br /> measured periodically during well development. Well development will be performed until <br /> groundwater is visible clear and free of sediment or until a reasonable length of time has <br /> }w <br /> been spent attempting to achieve clariv,. Development time for each well will not exceed <br /> la <br /> throe hours for any well. <br /> r At least 24 hours after development is completed, a groundwater sample will be colle;•vxf <br /> l!t <br /> !•tom each well. A minimum of sheer well volumes will be evacuated prior to sampling with <br /> a clean stainless steel bladder pump or stainless steel bailer. During well purging. the <br /> evacuated water will be measured for pH, temperature, electrical conductivity, and turbidity. <br /> Groundwater samples will be submitted to a state-certified analytical laboratory for analysis <br /> of TPH as gasoline, benzene. toluene. ethyibenzene, and xylenes using EPA Methods <br /> 101518020. <br /> �x.+c�'r..a•+rvs <br />