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4 Report-Soil and Groundwater Investigation Gateway Project,City of Stockton JI - April 10,2000 Page-4- The soil cores and s1amples.:were logged according to the-Unified Soil Classification'System. Geological 3 _ logs containing field observations including soil.type, estimated moisture content, the presence of staining or odor, and PID measurements are included in Appendix B. The soil sa'mples.were`collected with either a 1.75=inch diameter, 47foot long or a-2-foot long,.1.0-inch diameter,-core barrel', each fitted with"a": clean, one-time use, polyethylene liner." The soil'sampling equipment'was decontaminated-prior to .collecting each sample. The decontamination procedures consisted of washing the-.core barrel and associated down-hole tools in.a solution of'laboratary-grade, non-phosphate detergent and dc-ionized water, and double rinsing with de-ionized water. Soil samples were cut from each' liner at selected depths for laboratory analyses. Each soil sample was capped, labeled, and placed in a cooler chilled with ice and delivered within 24 hours of collection, under cha_in- - of-custody procedures,to GeoAnalytical Laboratories of Modesto, California. 3.3.2 Subsurface Soiil Conditions Based on our review of the tank pull activities and the field observations,it appeals that-native soil was r encountered in-GP 1 at approximately i 1_feet bgs. Very stiff clay and sandy clay were generally encountered'from i l feet bgs down to the total depth of the boring at approximately 30 feet bgs. Clayey 1 sand, however,was present at approximately 25 to 26 feet bgs in the soil core collected from - approximately 24 to 26 feet bg An attempt to obtain a soil sample from.20 to 22 feet bgs was unsuccessful (there was insufficient soil in the sampler-for soil sample collection). Field observations - generally indicated that although a very stiff, dry, clay was present in GPI between approximately I 1 and 12 feet bgs and again between 29 and 30 feet bgs, significantly sandier soil (sandy clay and clayey sand)was present between those depth ranges. PID measurements of.12, 2, 37, and 1.9 parts per million (ppm)total organic vapors and slight to moderate petroleum hydrocarbon odors were recorded for field observation soil samples collected from GPI at approximately 11.5, 15.5, 25.5, and 29.5 feet bgs, respectively. Native soil appeared:to be encountered in GP2 at-approximately 5 feet bgs. Stiff clay, sandy clay and dense clayey sand were generally encountered from`,5 feet bgs down to the total depth of the boring at approximately 30 feet bgs. Similar to GP1, field observations generally indicated that although a stiff clay was present in,GP2 between approximately 10 and 12 fect:bgs and again between 28 and 3 et CONDOR r- .