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IN <br /> Page 3 <br /> Groundwater Sampling <br /> The seven nroundwater monitoring wells sere developed on <br /> April 11 and 12, 1990 by means of surging and pumping. Each <br /> well was developed until the discharge water was visually <br /> clear, and free of obvious sand and silt by xemoving <br /> r approximately 5 .:ell volumes. An ISCO bladder pump driven by <br /> a nitrogen source was used to purge and develop the wells. <br /> Prior to sampling, groundwater was observed for general <br /> clarity and measured for temperature, pH, and conductivity to <br /> - <br /> evaluate t_nuilibrium. Samples were obtained with a Voss <br /> disposable: bailer, and a new bailer was used for each well. <br /> Samples were maintained and transported in 40-milliliter VOA <br /> vials placed in a cooler-chest on 'lice". A proper Chain of <br /> Custody accompanied the samples to a State-approved <br /> - laboratory for chemical analysis. Water from well <br /> development was contained in drums at the subject property, <br /> l and is pending proper disposal by Chevron U.S.A. <br /> Groundwater depths were measured in each well prior to <br /> sampling. The measurements were obtained using an electronic <br /> �. depth sounder, referencing the top of the rim of the <br /> permanent well vault. The rim of the well vault has been <br /> surveyed to provide an accurate reference elevation at the <br /> surface of each well head. Groundwater depths measured in. each well were compared to the surface elevation of each well <br /> head to establish a groundwater elevation. <br /> i <br />