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On January 11, 1990, BC personnel completed a visit to the GLDM site. The visit <br /> included the measurement of water levels and total depth of each well. These measurements <br /> showed that groundwater levels have declined since 1986, from approximately 44 feet below <br /> ground surface to 54 feet below ground surface. The wells have also become partially filled <br /> with sediment, in some cases up to 7 feet of sediment. Groundwater flow at the site is <br /> southwesterly. <br /> PURPOSE <br /> In order to begin soil and groundwa:r r characterization at the GLDM site, BC has <br /> County developed this work plan for the and Regional Board's review and approval. The <br /> work plart consists of several pans: soil characterization work, redevelopment and sampling <br /> of MWA, MW-2, MW-3, MW-4, and MW-5, and installation of an off-site monitoring well. <br /> The purpose of the soil characterization work is to better characterize hydrocarbon <br /> occurrence in the area of the former pump island. Although some information is known <br /> about the presence of hydrocarbons in the soil at the site, there is not enough information to <br /> determine the source of the hydrocarbons. <br /> The purpose of the red.velopment of wells MW_1, MW-2, MW-3, M4 W-4, and MW-5 is <br /> to remove the sediment that has accumulated in the wells. Following development, each well <br /> will be sampled in order to determine the quality of the groundwater each well yields. <br /> The purpose of the off-site monitoring well is to better characterize the presence of <br /> hydrocarbons in the groundwater leaving the site. Completion of this work will be dependent <br /> on obtaining off-site permission for installation of the well. <br /> FIELD METHODS <br /> This section describes the field methods for the on-site soil characterization, well <br /> redevelopment, and off-site groundwater monitoring well installation. The locations of public <br /> underground utility lines in the Cherokee Lame area are shown on Figure 3. Underground <br /> Services Alert (USA) will be notified prior to drilling. USA's member utilities will then mark <br /> the locations of their underground lines in the drilling area. <br /> On-Site Soil Characterization <br /> This section describes the borehole drilling and soil sampling methods for the on-site soil <br /> characterization. <br /> Borehole Drilling. BC will supervise the drilling of three soil boreholes at the GLDM <br /> site (see Figure 2). The boreholes will be drilled using a truck-mounted drilling rig equipped <br /> with 8-inch-outside-diameter, hallow-stem augers. Borehole depths are not expected To be <br />