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CLOSURE REQUEST 5-31-94 completed on August 16, 1990, see Table 5. This soil was then compacted backfilled into the UST excavation by Walton Engineers, from the 12 foot depth to the three foot depth. The base of the excavation (26 foot depth to 12 foot depth) was backfilled with 1/4" pea gravel and capped with typar matting for later use as a vapor extraction area, if needed. Over-excavation of the pump island areas on August 22 , 1990, generated approximately 350 cubic yards of soil . Sample results of this soil showed it to be exempt from aeration guidelines and permission to aerate the soil was granted on September 6 , 1990, at 350 cubic yard increments. After completion of the aeration this soil was used for compacted backfilled into the pump island excavations (after they were backfilled to approximately the ten foot depth with 1/4 inch round pea gravel which was capped at the ten foot depth with typar matting) and the remainder was used to bring the UST excavation up to grade. Upon completion of the backfilling, vapor recovery wells P1, P3 and EX were installed into the pea graveled areas of the eastern pump island excavation, the western pump island excavation and the UST excavation respectively. Then the entire area that were over- excavated was covered with 10 mil polyethylene liner that overlapped the still existing asphalt or concrete surfaces, seams were field welded together to create one solid liner. All soil generated from the soil borings for the confirmation sampling, the vapor recovery well and the ground water monitoring well installations were aerated on site and used as backfill or have been spread thinly on the surface of the site for aeration. Excavated Soil Treatment The excavated soil was stockpiled on the asphalt or concrete areas of the site and covered (polyethylene liners) until sample results indicated how to treat the soil Although the soil has a moderate to high silt and clay content and the contaminants ranged in the gasoline-diesel groups it was felt that aeration should be tried Aeration of the excavated soil generated from UST and product line removal commenced on November 7, 1989 The Aeration Permit granted active aeration of 54 cubic yards per day. This was accomplished by splitting 50 cubic yards of soil from the covered piles and spreading and moving this soil for 8 hours a day using a front end loader with a one yard bucket At the end of the day the 50 cubic yards of soil was spread six inches deep and left, until the next morning. The following morning the aerated soil was placed into a pile and covered and a new 50 cubic yard segment of the covered excavated soil_ was removed and worked as described above. This aeration practice continued until the entire pile had been worked through at least once Aeration of the original piles) was completed on May 25, 1990 Over-excavation of the UST area produced another 200 cubic yards of soil . This soil was sampled on July 17, 1990 and aeration commenced on August 10, 1990 This soil was spread six inches page22