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_ Di Salvo-Lathrop MW 1 Report June 28. 1995 Page-3- 3.1 Field Methods - Drilling Prior to use, the augers were steamed cleaned and all sampling equipment was washed in a solution of non-phosphate detergent and laboratory grade, hydrocarbon-free water and triple rinsed in hydrocarbon-free water. MW1 was drilled using 8-inch O.D., hollow-stem, continuous-flight augers. The monitor well was located within the former tank excavation and fill material was encountered to a depth of approximately 9 feet _ bgs. At approximately nine feet bgs, a 24-inch California-modified, split-spoon sampler fitted with four clean brass tubes was advanced ahead of the auger bit to a depth of approximately 11 feet bgs. Soil samples were collected using a 140-pound hammer with a free-fall of 30 inches onto the sampling rods. The upper-most tube was discarded. The 2 middle sample tubes were retained for geologic logging and field screening. The bottom-most tube was immediately sealed with Teflon tape, capped, wrapped with duct tape, labeled, and stored in a cooler chilled with Blue Ice to await shipment to the laboratory. The augers were then advanced from 9 feet to approximately 1 1 feet bgs and the sampler was advanced ahead of the auger bit to approximately 13 feet bgs. The upper-most tube was discarded and the bottom and 2 middle tubes were immediately sealed with Teflon tape, capped, wrapped with duct tape, labeled, and stored in a cooler chilled with Blue Ice. A battery-operated, flat-tape, water-level meter was lowered inside the augers to evaluate for the presence of groundwater. The water level meter indicated wet soil was present inside the augers at approximately 12.5 feet bgs but groundwater was not present. The augers were then advanced from 11 to 13 feet bgs and the sampler was advanced ahead off the auger bit to approximately 15 feet bgs. The water level meter was lowered inside the augers and the static water level was measured at approximately 12 feet bgs. To confirm the depth of static water level and collect a soil sample for geologic description, the augers were then advanced from 13 to 15 feet bgs and the sampler was advanced ahead of the auger bit to approximately 16.5 feet bgs. The water level meter was lowered inside the augers and the static water level was again measured at approximately 12 feet bgs. The soil sample was saturated and contained silt at a depth of approximately 16 feet bgs. To evaluate the thickness of the silt, the augers were advanced from 15 feet to approximately 16.5 feet bgs and the sampler was advanced ahead of the auger bit to a depth of approximately 18.5 feet bgs. The soil sample was wet and contained 100% silt. The boring was terminated at a total depth of approximately 18.5 feet bgs. A geologic log of MW1 was prepared by a Condor geologist trained and experienced in the use of the Unified Soil Classification System under the supervision of a registered engineer. Soil samples were screened in the field using a portable OVA. The soil cuttings from the borings were containerized in 55-gallon DOT approved drums, sealed, labeled, and left on site pending the results of laboratory analyses. Disposal of hazardous materials, if any, is the responsibility of Di Salvo Trucking. �� CONDOR