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.-- Report on Additional Excavation and Wfirmation Soil Sampling Bulk Transportation Facility, Stockton, California L Hygienetics Environmental Services,Inc. feet below grade; a minor area of discoloration was also observed'at 12 feet below grade. The original pipeline trench was widened from 1 to 2 feet to the south and to the north. Little discolored soil was observed along the western portion of the southern sidewall. Substantially more discolored soil was observed to a depth of 10 feet'l below' the ground surface during excavation along the northern sidewall. The western end of the trench was excavated to a depth 1 of I0%2 feet below grade on July 29 and no discolored soil was observed in this portion of the pit. 1 Foss continued excavation on July 30 to remove slough material and clean out and prepare the excavation for confirmation soil sampling. A CaterpilIer 312C excavator was used to extend the depth of excavation from 14 to 14%2 feet below grade. At this point, visibly discolored soil was removed. Foss placed the excavated soil in two stockpiles on the northern and southern sides of the excavation. Based on the measured dimensions of the two stockpiles, the volume removed is estimated to be 110 cubic yards of uncompacted soil. Plate 3 shows the final configuration of the excavation on July 30, 2003 and Plate 4 shows the locations of the two stockpiles. i1 2.3 Sampling Soil Hygienetics collected six soil samples from the excavation on July 30. Two samples were collected from the northern sidewall at depths of 9% and 11%2 feet below grade, two samples were collected from the southern sidewall at a depth of 10 feet below grade; and two-1 samples were collected from the bottom of the excavation at depths of 14 and 14'/2 feet below grade. Mr. Jeffrey Wong of the ` Environmental Health Department was present to observe the sampling. Plate 3 shows the locations at which samples were collected; the sample designations (e.g., S-14'/2-Bottom 1) indicate the depths at which samples were collected. u The soil samples were collected directly from the sidewalk and bottom of the excavation using a slide-hammer-sampling tool attached to an extension rod. The sampling tool contained a 2-inch- diameter by 6-inch-long clean brass sleeve. The sampling tool was lowered to the desired sample location, driven a minimum of 6 inches into the native soil, and withdrawn. The brass sleeve was removed from the tool and each end of the sleeve was covered,,with a Teflon sheet and plastic end cap and was wrapped with duct tape. A clean brass sleeve waslthen placed in the sampling tool for the next soil sample. Each brass sleeve was labeled with the sample designation, date, and job number and was placed on ice in a cooler promptly after collection. Hygienetics prepared a Chain- of-Custody form for the samples and this form accompanied th'e samples to the laboratory. A copy of the Chain-of-Custody form is included in Appendix B. Hygienetics collected two individual soil samples from the southern stockpile and two individual soil samples from the northern stockpile for compositing and analysis in the laboratory. Samples S-Stockpile-A through S-Stockpile-D were collected at locations shown on Plate 4 to characterize the soil stockpiles for disposal purposes. Mr. Wong also requested that a representativeindividual sample of the stockpiled soil be collected for laboratory analysis to evaluate the ;maximum concentration of diesel hydrocarbons in the soil removed from the excavation. Hygienetics collected sample S-Stockpile-1 for the individual analysis at the locationshown on Plate 4. The stockpile soil samples were collected and sealed in clean brass sleeves and were labeled and placed on ice as described for the excavation soil samples. Hygienetics prepared a separate Chain-of-Custody form for the stockpile soil samples and this form accompanied the samples]to the laboratory. 'A copy of this form is included in Appendix B. I� C 4 d,