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a <br /> t <br /> 7 <br /> r <br /> II3,-'A <br /> i <br /> 1 On November 20, iyUa: the Regional Board notified GLDM by letter that GLDM must <br /> complete an investigation to determine the full ement of contamination resulting from the <br /> possible release of hydrocarbons at the GLDM site. As part of this investigation. Geweke <br /> 15 retained BC to prepare a work plan for completing a problem assessment report. The work plan <br /> ie to include the ir_stallation of monitoring wells to define the full extent of groundwater <br /> contamination at the site. <br /> { On January 11, 1990, BC personnel completed a visit to the GLDM site. The visit included <br /> the measurement of water levels and total depth of each well. These measurements showed that <br /> E" groundwater levels have declined since 1986, from approximately 44 feet below ground surface <br /> f to 54 feet below ground surface. The wells have also become partially filled with sediment, in <br /> a.r <br /> some rases up to 7 feet of sediment. Groundwater flow at the site is southwesterly. <br /> s :. <br /> r PURPOSE <br /> r = <br /> In order to begin groundwater characterization at the GLDM site. BC has developed this <br /> s work plan for the County and Regional Board's review and approval. The work plan consists <br /> of several parts: redevelopment and sampling of existing monitoring wells MW-1. MW-'-,' <br /> ' MW-3, MW-4, and MW-5, and installation of four off=site monitoring wells. <br /> N <br /> k <br /> -" The purpose of the redevelopment of wells MW-1, MW-2, MW-3,N'N-4, and MW-5 is to <br /> i` remove the sediment that has accumulated in the wells. hollowing development,each well will <br /> be sampled in order to determine the quality of the groundwater each well yields. <br /> The purpose of the off-site monitoring wells is to better characterize the presence of <br /> ' hydrocarbons in the groundwater surrounding the site. Completion of this work will be <br /> dependent on obtaining off-site permission for installation of the wells. <br /> FIELD METHODS <br /> This section describes the field methods for the well r;.developmrnt and off-site groundwater <br /> monitoring well installation. The locations of public underground utility iines in the Cherokze <br /> Lane area are shown on Figure 3. Underground Services Alert (USA) will be notified prior to <br /> drilling. USA's member utilities will then mark the b=atons of their underground lines in the <br /> drilling area. <br /> Well Redevelopment and Sampling <br /> ;-� Monitoring wells MV-1, MW-2, MW-3, MW4, =d MW-5 will be redeveloped by <br /> "vacuuming"sediment from the well using a diaphragm pump. After vacuuming Trach well,they <br /> will be surged using a stainless steel bailer. The wells will then be purnp-d again to remove any <br />