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1 Sutter Office Center Project 2267--E July 10, 2000 Page 5 laboratory provided containers and delivered to the testing laboratory in an ice chest. Soil ' samples were encapsulated in plastic tubes, with the ends sealed, and placed on ice for delivery to the Vironex testing laboratory, which is certified by the State of California ' (ELAP#2250) The results of the soil and groundwater analysis is presented in the attached Appendix C ' and summarized on Plate 3. Residual hydrocarbons were noted in two of the soil samples at a depth of 10 feet Probe "A"encountered 33 ppm (parts per million) of TPH-diesel at a depth of 10 feet, and 100 ppm of TPH-gasoline was present at this depth in Probe "B", which is located approximately 35 feet south of Probe "A". A minor amount of TPH- gasoline (4 ppm) was present in the soil at a depth of 20 feet 1n Probe "G", which is ' within the general groundwater zone, upgradient from the abandoned underground storage tanks Petroleum product was present in the groundwater in Probes "A", "B", "C", and "F", with TPH-gasoline ranging from 470 ppm to 0 55 ppm, see Plate 3 As indicated by our probes, the shallow groundwater aquifer underlying this site appears to be confined below a low permeability clay layer at 35 to 40 feet below the ground ' surface The potentiometric surface of the confined groundwater under the site, as observed in our probes at the time of our field sampling, vaned from 22 to 26 feet below ' the ground surface. ' FINDINGS The on-site spillage of petroleum fuel in the soil at a depth of 10 feet appears to be ' related to leakage at the pumps rather than from the underground storage tanks. There is 33 ppm of residual diesel fuel at Probe "A" and 100 ppm of residual gasoline at Probe ' "B". These levels are below the 1,000 ppm limit requiring excavation and disposal at an approved site, under the Regional Water Quality Control Board's general criteria le�� yv' ' HYDRO-GEO CONSULTANTS,INC