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Libber•Owens Ford Co. Product Recovery System Installation June 23, 1997 Page-5- proximity to the source (i.e., diesel pipeline). We anticipate that a majority of the soil excavated from the area near or along the pipeline will be impacted with diesel. The soil excavated from the outer lying trenches is anticipated to be clean overburden from the ground surface to the capillary fringe (approximately 10 feet bus). Diesel impacted soil in the outer lying trenches is expected to be encountered at and below the water table. We estimate that approximately 100 cubic yards of diesel contaminated soil will be excavated during the trenching. The contaminated soil will be stored at the site in bins or a covered stockpile pending disposal at an approved facility. 3.2 Product Recovery Wells Six (6) product recovery wells will be installed in the trenches to a depth of approximately 15 feet bus (Figure 4, Appendix A). The wells will be constructed of Schedule 40, flush threaded, PVC casing. Each well will be screened from 5 to 15 feet bus and capped at the bottom. A blank PVC riser will be installed from 5 feet bus to the ground surface. Following placement of the wells, the earth dams in the trenches will be excavated and the trenches will be backfilled with pea-gravel to approximately 4 feet bus. Geofabric will be placed over the pea gravel and clean native soil will be placed above the geofabric to approximately I foot bus. The trenches that cross the roadway will be patched to match existing pavement. Each well head will be completed with a locking, water tight cap and a traffic box anchored in concrete (see Figure 5„Appendix A, Product Recovery Well Design). 3.3 Product Recovery Skimmer The proposed product recovery system consists of a portable, self contained, pneumatically operated skimmer manufactured by Xitech Instruments Inc., of Fairfield, California (Model - ADJ 1000 Smart Skimmer). The skimmer will be installed at a selected product recovery well and moved periodically to other recovery wells, as warranted, to optimize effectiveness. The skimmer is operated by compressed gas which will be supplied by nitrogen cylinders. The skimmer float slides up and down on a 30-inch long travel guide which serves to center the device in the well. The skimmer float follows the fluctuation of the water level in the well and maintains its designed inlet level at the product-water interface. A semi-permeable screen inside the skimmer float allows product to pass into the skimmer, while repelling water. The product recovered by the skimmer will be pumped into DOT approved 55-gallon drums equipped with an automatic high-level shut off switch. The recovered product will be stored on site for recycling at an approved facility. L, CONDOR