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i WORK PROPOSAL - Installation of Monitoring Wells / Confirmation of CPT Define Vertical Migration California Geophysical Group now proposes to install two 2" PVC Monitoring Wells (MW-17 and MW-18). They will be placed on the south eastern corner of the site near Charter Way and Grant Street. Each well is near the location of the CPT (Boring # B-4) , see the attached overview Site Map for location details. We have also included a cross sectional map describing the location and placement of these two new wells in relation to the CPT and monitoring wells. The surface area where these wells will be installed is level and stable . The surface area is either cement or asphalt with an engineered surface storm water drainage system . Careful consideration will be exercised in the placement of the wells due to the fact that this is an active gasoline station in full operation. The wells will be permitted through the San Joaquin County Environmental Health Department and will be installed only with their approval. The monitoring wells will be named MW- 17 and MW- 18, respectively. Each well will be drilled via a truck mounted hollow stem auger. MW- 17 will be drilled to a depth of 135 vertical feet and will be screened from 125 to 135 feet bgs. MW - 18 to a depth of 160 vertical feet and it will be screened from 150 to 160 feet. MW- 17 is being installed to investigate and evaluate the potential for lateral movement of the contamination plume through the sandy layer of sediment encountered during the installation of the CPT. It is also being installed to determine and confirm if contaminates are present at this depth . Additionally, MW- 18 is being installed to follow-up and confirm the findings of the bottom hole sample collected in the CPT, which indicated contamination at 158 feet bgs. The drilling tasks will be performed with a hollow stem auger by Spectrum Drilling of Stockton , Ca. The wells will be drilled with an 8- inch hollow stem auger and PVC cased to a completed depth of 135 feet and 160 feet below the surface (bgs) . Soil samples will be taken every 5 feet with a split spoon — driven core sample unit during the drilling operations and analyzed with an OVA meter. During the drill process of well MW-17, predetermined soil and water samples will be collected from 82, 120 and 135 feet, respectively. Each sample collected will be sealed on-site, placed in an ice chest with ice and preserved for transportation to Argon Laboratories in Ceres, CA. for analytical testing as outlined in the Laboratory Testing Section of this work plan. In the process of the field screening , any other soil samples not listed in the predefined sample points, test positive during the OVA screening in the field they also will be submitted for the same analyses. During the drill process of well MW-18, predetermined soil and water samples will be collected from 40, 70, 85, 120, 132 , 150 and 160 feet, respectively. Each sample collected will be sealed on-site, placed in an ice chest with ice and preserved for transportation to Argon Laboratories in Ceres, Ca. for analytical testing as outlined in the Laboratory Testing Section of this work plan. In the process of the field screening, any other soil samples not listed in the predefined sample points, test positive during the OVA screening in the field they also will be submitted for the same analyses. Monitoring Well MW- 17 will be built by placing a section of 0. 020 slotted PVC casing into the bottom 10 feet of the boring. Then 10 foot threaded sections of Schedule 40 PVC blank well casing will be threaded together from 125 feet to the surface. Number 3 sand pack will be placed opposite the slotted casing and 5 feet above it and slowly surged and consolidated prior to placing 3