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Q Limited Phase 11 Subsurface Investigation Report 902-908 East Scotts Avenue Stockton,California a ntea g ro u p Antea Group Project No. UPR82572A 3.2.2 Soil Screening Antea Group personnel field-screened soil samples at approximate two-foot intervals using a field-calibrated photoionization detector (calibrated to a 100 part-per-million isobutylene standard). The field geologist placed a portion of representative soils into a plastic bag, sealed it, and allowed it to rest for about 15 minutes prior to collecting a reading. A reading was obtained by inserting the PID's tip into the airspace in the plastic bag. Trace PID readings ranging from 0.0—2.0 parts per million (ppm)were recorded in most borings. PID readings above 2.0 ppm are summarized in the table below: Boring ID Depth(ft bgs) PID(ppm) B3 2 853 3 5.0 B6 5 4.3 1 40.5 B7 4.5 2.3 B15 1 4.7 The boring logs in Appendix B show the PID screening results at each recorded interval. In addition, the field geologist logged soils for geologic characteristics, as well as any visual, olfactory, or other indicators of contamination. In general, shallow soils consisted of variable fine-grained materials across the site. The western portion of the site was primarily dark brown clay to five feet bgs, the central portion of the site was primarily orange-brown silt to five feet bgs, and the eastern portion of the site consisted of orange-brown silt to 2-3 feet bgs and dark brown clay to five feet bgs. The five borings (133, 136, 1313, 1315, and 1318) advanced to 10 feet bgs consisted of red-brown silt or orange-brown clay with dark brown mottling in all of the borings except boring 133, which was orange-brown clay to approximately seven feet bgs and then yellow-brown silty sand to 10 feet bgs. Groundwater was not encountered during the investigation. 3.2.3 Soil Sample Collection For potential surface releases, Antea Group personnel sampled the upper two feet of soils beneath the pavement. For subsurface features (i.e., drains, sumps or oil/water separators), Antea Group sampled soil at, or just below, the approximate bottom depth of the feature. For the borings advanced to 10 feet bgs, a soil sample was also collected at depth for potential deeper vertical delineation of contamination (shallower data did not warrant analyses of the deepest collected samples). The geologist collected soil samples directly from the hand auger or disposable acetate liners into laboratory-supplied glass soil jars with Teflon°-lined lids. The Antea Group geologist labeled the jars with the sampling location, depth, and other details (e.g., date and time collected) before placing them on ice in a cooler for proper preservation prior to their submittal to TestAmerica Laboratories, Inc. in Pleasanton, California, a state-certified laboratory. Sample names, depths, and details were recorded on an 5 www.anteagroup.com