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<"%TC A S S O C I A T E S I N C . SCOPE OF WORK Drvwell Abandonment ATC proposes to abandon on-site drywells NW, SW, NE, and SE. The drywell locations are shown on Figure 2 in the bottom of a pond area. The depth of the pond area is approximately four feet below ground surface (bgs). The drywells are approximately 30-inch diameter and 25- feet deep. In the center of each drywell is a 4-inch steel center pipe. A small ramp will be constructed in the southwest corner of the pond area to provide access for the equipment necessary to complete the drywell abandonment. The well monuments will be removed from the top of each well. ATC personnel will monitor the site and soil cuttings with a flame ionization detector during the abandonment of the drywells. A vacuum rig will be used to remove gravel Qo,Z from around the center pipe of each drywell. First water will be injected into the drywell to/ loosen up the gravel pack. The gravel and water will then be removed from the drywells using the vacuum rig. Near each drywell a shallow pit will be excavated and lined with visquene plastic. The gravel, injection water, and soil cuttings from each drywell will be placed in these pits and one composite soil sample will be collected from each spoils pile. After removing as much gravel as possible from each drywell, the center pipe from each drywell will be removed using a bucket auger rig. The bucket auger rig will then overdrill each drywell to the anticipated total depth of each drywell, approximately 25 feet bgs. Once the bottom of each drywell has been verified, another two feet of soil will be removed from each drywell and a soil sample will be collected from the bottom of each drywell. Soil cuttings will be placed in the dedicated pits described above. Soil Sample Analysis In accordance with the PHS/EHD Guidelines for Closure of Shallow Dry Wells, all eight samples (four bottom samples and four cuttings samples) will be analyzed for volatile organic chemicals (VOCs) by EPA method 8260, semi-volatile organic compounds (SVOCs) by EPA Method 8270, total petroleum hydrocarbons as gasoline (TPHg) and as diesel (TPHd) by EPA method 8015, total oil and grease (TOG) by method 5520, and for toxicity characteristics of metals CAM 17 by TCLP analysis. A State-Certified analytical laboratory will analyze all eight soil samples on a 24-hour tum-around time. Borehole Backfilline �o v' Once analytical results have been received ATC will verbally request regulatory approval to backfill the borings, if appropriate. The drywells will be backfilled with a sand slurry from the bottom to 8 feet bgs. The drywells will then be capped with a cement slurry from 8 feet bgs to the surface. Both slurry mixtures will be delivered to the site by an aggregate company and