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I TlreadweIKMlo �y samples were collected from each boring, in both the shallow and deep zones at approximately 30 and 60 feet bgs. The soil borings in the first two phases of the Site investigation were drilled by Resonance Sonic Drilling using a direct-push and hollow stem auger combination drill rig. Soil borings were advanced using a -) 3 .5-inch diameter drive casing with an inner sample barrel . Continuous soil cores were collected inside the sample barrel using four-foot disposable acetate liners. After being advanced approximately 4 feet, the full sample barrel was retrieved while the drive casing was left in place to prevent the hole from i collapsing and to prevent cross contamination between the shallow and deep zones. Samples were i generally collected at 5-foot intervals from 20 feet below ground surface to depth. - The soil borings in the last phase of the Site investigation were drilled by Spectrum Exploration Inc. using a hollow stem auger drill rig. Borings were advanced using 8-inch diameter augers with an 18-inch split spoon sampler. Soil cores were collected in 1 .5•inch brass tubes inside the sample barrel. Samples were generally collected at 5-foot intervals from 50 feet bgs to depth. Soil samples from the continuous cores, brass tubes, and the test pits were screened in the field for the presence of volatile organic vapors using a portable organic vapor meter (OVM) with a photoionization detector with a 10. 2-electron-volt lamp. Recorded OVM measurements are presented on the soil boring logs (Appendix A). - ) After the sample cores were retrieved and logged, selected tubes were saved for chemical analysis. The sample tube ends were covered with Teflon"' sheets, sealed with plastic end caps, labeled, and stored in an ice-cooled chest for delivery to the analytical laboratory. To facilitate grab groundwater sample collection in the shallow zone, the boring casing was pulled up to ifs approximately just above the groundwater elevation, and a temporary one-inch diameter slotted PVC casing with a 5-foot long screen interval was placed into the boring . To facilitate grab groundwater -_ sample collection in the deep zone a hydropunch sampler was used with a two- to five-foot screen interval . Groundwater grab samples were collected using a dedicated disposable polyethylene bailer. All groundwater samples and selected soil samples were submitted to STL Chromalab, a California state- certified laboratory for analysis using chain-of-custody protocols. 6 25971201 . DGD 6 February 2008 J i