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Emergency Remediation - 2480 Tracy Blvd., Tracy, CA. • Page 11 dispose of the contaminated water generated by this process are described in subsequent sections of this report. A total of approximately 350 cubic yards of contaminated soil, as measured in situ, was excavated by the remediation contractor to provide for construction of the basement foundation slab. This work was performed with a Komatsu PC-20OLC-5 excavator equipped with a 44 in. bucket. A Case 821 front loader with a 4 cu. yd. bucket was used to stockpile the excavated soil. Immediately after the basement excavation was complete, the remediation contractor placed and compacted rock and sand sub-base materials to receive the basement slab concrete. As soon as that work was complete, the concrete sub-contractor graded the base materials, installed the reinforcing steel and poured the slab without delay. The basement structure was then completed and the waterproofing contractor bentonite-fabric waterproofing material was applied to the exterior of the walls. When the space between the basement walls and the perimeter of the excavation was backfilled, the waterproofing contractor extended the previously-installed dewatering drains upward to conform with the new elevation of the basement slab. This will allow any vadoze zone water that accumulates behind the basement walls to drain away. Later in the remediation project, contaminated soil was excavated to install a 10,000 gallon wash-water recycling tank. This operation generated approximately 60 cu. yds. of contaminated soil. The remediation contractor performed the excavation work, placed bedding materials in the bottom of the tank pit, set the tank into position, and placed the granular backfill around it. Because the bottom of the tank pit was at a depth of approximately 12 ft. beneath the ground surface, the tank was submerged below the water table to a depth of some 4.5 ft when set in its final position. To effect the tank installation without pumping contaminated water, the deepest portion of the tank pit was opened by extracting below the water table. Rock and pea gravel was placed in uniform layers in the bottom of the flooded pit and the tank settled onto it by filling the tank with water until it slowly sank. Ropes were used to maintain the tank in the correct position and orientation as was submerged Approximately 8,000 gallons of clean water that had been treated and tested after it had been pumped from the basement dewatering system were used for this purpose. The procedures used to treat and test that water are described later in this report. Excavation of contaminated soil by the remediation contractor was strictly limited to the minimum required for construction of the car-wash and automobile-lubrication facility. However, it was found that the spoil heaps generated by the first phase of excavation for the basement, which was underway when gasoline-contaminated soil was first identified, contained comingled clean and contaminated soil which it was not practical to segregate. Thus, all of the soil excavated from the basement pit was handled as though it were