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- ms ,&SR <br /> i � <br /> 9 <br /> �`• additional sediment dislodged by the surging process. The wells will be allowed to recover fully <br /> prior to sampling. Water and sediment produced during well redevelopment and sampling will <br /> be contained in 55-gallon barrels. GLDM will be responsible for disposal of water,sediment and <br /> s any recovr":-ed petroleum product. Prior to and following redevelopment, the depth to water will <br /> be measured using an oil/water interface probe. <br /> ` Groundwater Sampling. Prior to sample collection, at least three well volumes of <br /> grounawatcr will be removed. A well volume is defined as the amount of groundwater if, the <br /> well casing and the sand pack with an assumed porosity of 35 percent, The pH and electrical <br /> conductivity of the water will be measured periodically prior to sample collection. <br /> Groundwater samples will be obtained with a teflon bailer. Sample bottles will be filled to <br /> the brim directly from the bottom-timptying valve of the Lailer. A teflon.-lined cap will be placed <br /> en the bottles, and the botties will be checked to determine that no aur bubbles remain within. <br /> All water samples will be labeled, stort:d, and transported as described in the soil:.,ampiing <br /> section above. The water samples will be submitted to BCAL for analysis of BTX and TPH by <br /> EPA Method 8015, modified,Extraction Method 5030. <br /> a. <br /> In;ta;la►ion of Off-Site Groundwater Monitoring Wells <br /> 'Phis section desrribes ;he methods for monitoring well construction,, development, and <br /> sampling. GLDM proposes to install three monitoring wells downgradient of the site. GLDM <br /> also proposes one upgradient monitoring well. The construction of wells and locations will be <br /> subject to approval of landowners. The three downgmdient wells will be located southwest of <br /> the former psmp islands and USTs,and south of the southern property boundary. The upgradient <br /> well will be located north!ast of the site's northern property boundary. <br /> f <br /> Borehole Drilling. DC will supervise the drifting of four off-site soil boreholes and the <br /> installation of groundwater monitoring wells in each of the boreholes (see Figure 2). The <br /> boreholes will be drilled using atruck-mounted drilling rig equipped with 8-inch-outside- <br /> dLarne.tV•r,hollow-ste,:!Augers; Borehole depth is expected to be 70 feet. Borehole cuttings will <br /> be crib ained in 55-gallon drums and temporarily storcd at the site. The disposal of these drill <br /> cuttings is the responsibility of GLDM. <br /> Soil Sampling. Continuous soil cores for iithologic classification will be collected from all <br /> boreholes to the total depth of the borehole using5-foot-long,5 <br /> a oa[ 1 <br /> ong, sellersampling barrel inside the <br /> ager. Samples for laboratory analysis will be collected using a 1.54 of-long,split-spoon drive <br /> sampler, lined with three 2-inch-diameter brass liners. The sampler will be driven into <br /> undisturbed soil ahead of the augers. <br /> T'he,lithoIogy of each borehole will be described according to the Unified Soil Classi- <br /> ,� ficadcn System. The boreholes will be Iogged by an experienced fiela a_ologist working under <br /> the direr: supervision of a registered geologist. Cbs:rvations of visible hydrocarbons and <br /> ;' hydrocarbon odors will also be noted. The soil samples will be screened on site with a portable <br />