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i collected at various depths and from several stratigraphic units to provide a comprehensive evaluation of the site The samples were collected with a slide hammer loaded with two 2 x 3-inch brass sleeves After a pair of samples were collected, the geologist was raised to the surface and the samples were passed to a representative of Elite IV for sealing and labeling After the samples had been capped and labeled, they were placed into a cooled ice chest and the sample barrel was rinsed in a TSP solution and reloaded The sling seat was then lowered again and moved to the next sample station When sampling was completed, the samples were transported under chain-of-custody to E_xcelchem Environmental Laboratories in Roseville 5.0 SITE GEOLOGY _ The size of the excavation and the use of a crane for sampling provided an exceptional opportunity to study the site geology to provide data on potential hydrocarbon migration pathways as well as assess the potential for m-situ remediation, should it be necessary Geologic descriptions at each sampling station were supplemented with photographs to construct four cross sections of the excavation (Figures 6-8) 5.1 Stratigraphic Units . Based on grain size and color, ten stratngraphic units were recognized Several units were traced continuously across all of the sndewalls, although units 3, 4, and 6 were absent or mdistmct locally and units 8-10 were exposed only to the deepest portion of the excavation _ Unit 1-- The uppermost unit is the modern soil horizon, and ranges from 4 to 6 feet in thickness This unit was very distinct on the north, east, and south walls, which were steep, but was less obvious on the sloping west wall It is medium brown in color, and grades upward from fine-grained sand at the base to silt Unit 2-- This light-gray Iayer consists of fine-to-very-fine-grained sand and is several feet thick Sample JL-P-3, collected during the initial dispenser-island sampling, was collected from this unit Unit 3-- Unit 2 is underlain by a darker gray clay or clayey sand that was most distinct on the east wall Gasoline odors were generally evident in this layer during excavation, and a slight odor was detected in this unit at sample point JL-P-21 Unit 4-- Unit 4 is a thin sand bed that grades upward from coarse-grained or gravely to medium grained The base of the unit is sharp and appears to be erosional into unit 5 Where unit 3 is absent, unit 4 could not be distinguished from unit 2, but it appears that sample JL-P-15, which emitted a moderate gasoline odor when collected, came from the upper part of unit 4 or the lower part of unit 2 s4