ARCHIVED REPORTS_XR0009846 - Laserfiche WebLink

Home Browse Search

the asphalt in two locations in the middle of where the tank had been located, and obtaining soil samples using a backhoe bucket. The operation was witnessed by San Joaquin Co. EHD personel . The soil samples were analyzed as required by the waste disposal firm so that removed spoil could be taken directly to the disposal site as it was excavated. After County approval of the workplan, and arrangements had been made to transport the removed spoil directly to Forward, Inc. work began on November 5, using a Jim Thorpe Oil JD 690C excava- tor operated by Rich Thorpe. W. J. Hunter, RG, supervised oper- ations, which were witnessed by Michael Collins of the County EHD. Starting at the north end of the site, the asphalt covering and the clean fill was removed by the excavator bucket and stored against the south property line using a backhoe operated by Jamie Thorpe. After removing the clean fill to a depth of about 5-6 feet, the original removed soil was encountered. That material was placed directly in a dump truck parked adjacent to the excavation. The north end was excavated to a depth of about 12 feet, with dimensions of about 12 feet wide and 20 feet long. The top 2-3 ' consisted of black adobe loam, very sticky and plastic. The adobe graded irregularly to a tan to buff clay, firm but not plastic, with occassional streaks of harder clay layers. There were no odors or evidence of contamination noted. Using the excavator bucket, a soil sample was taken from the bottom center of the excavation, ( 12 ' deep , ) about 5 feet from the north wall . Using a clean, 2" X 6" brass tube, the geologist collected a sample from the teeth of the bucket. It was quickly sealed with teflon tape and plastic end caps, and wrapped with duct tape. The sample was labeled and placed on ice pending transport to the laboratory. That sample is identified as "btm-No_ ( 12 ' ) on Plates VI & VII. At this point, the truck was full , and while it was transporting the material to Forward Inc. for disposal , the removed spoil was placed on the asphalt pending the return of the truck. The excavator moved to the south end of the excavation, and soil removal continued. The clean fill was stored in a separate pile than the underlying spoil , which was placed in the empty truck, (which had returned from Forward,. ) At this time, the sire of the excavation was approximately 12 ' wide and 30 ' long, grading from 12'deep at the north end to about 9-10' at the south. While removing spoil from a depth of 10-12 , about 20 feet from the north end , a very strong petroleum odor was noted , and the removed spoil revealed obvious staining and discoloration. As digging progressed, the contamination appeared to be strongest on the east and south wall , and the bottom. The west wall did not 4