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+..� •*411 2.3 Groundwater Depth and Flow Direction The groundwater depth at the site is approximately 35 feet based upon groundwater depth measured at the site located at 1045 West Charter Way, also owned by NCC. The groundwater flow direction at the 1045 West Charter Way site has varied, but currently is east-northeast. Since the subject site is approximately 2 blocks away from 1045 West Charter Way, it is assumed that the groundwater flow direction is the same. 3.0 PROCEDURES 3.1 Drilling and Sampling On December 20, 1994, one soil boring was drilled at the site. The boring was drilled near the center of the former USTs, and advanced to a depth of 30 feet. When drilling was complete, the boring was backfilled to the surface with Portland Cement. The location of the boring is shown on Figure 2. The boring was drilled using a truck-mounted CME 75-HT drill rig. The drill rig and two- man crew were supplied by Soils Environmental Services (SES) of Benecia, California. Soil samples were collected at five-foot intervals using a split tube sampler loaded with three clean, 2-inch by 6-inch brass sleeves. A 140-pound hammer was used to advance the sampler 18 inches; the number of blows required to advance the sampler in 6-inch increments was recorded on the boring logs. All sampling equipment was washed in an Alconox solution and rinsed twice with water prior to each sampling run. For each sample, both ends of the lead tube were covered with aluminum sheets, capped and sealed with tape. The samples were then stored on ice and transported under chain-of- custody to Analytical Bio-Chemistry Laboratories Pan-Ag Division (Pan-Ag) in Madera, California. During drilling, auger returns were monitored for the presence of organic vapors using a photo-ionization detector (PID: Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene). Auger returns were then placed on plastic sheeting and stored on-site. 3.2 Logging Soil was extruded from the second brass tube and screened for the presence of organic vapors, using a PID, and the readings were recorded on the boring logs. The soil was then described in accordance with the Unified Soil Classification System (see Boring Log, Appendix A). 0-4.S"I A.du S.ry.lac. 4 Pbmelliai 939 PIEM037/D-1991 .r