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`r fr¢alogicalrecluricslfu. � � Site Characterization Report page 2 Project No. 1218.2 February 9,2006 La 2.0 SCOPE OF INVESTIGATION Prior to commencing work, a soil boring/monitoring boring/monitoringwell permit was secured and Joaquin County Environmental Health Department (SJC/EHD) was notified 48 hours San 16dadvance. The subsurface was cleared of underground utilities by notifying Underground Service Alert (USA). 2.1 Soil Boring Installation '"` On January 4 — 5, 2006, Resonant Sonic International (RSI) of Woodland, California, and GTI personnel mobilized to the Broadway site. The USA markings were checked to see if `a there were utilities near the proposed borehole locations. A hand boring was completed to a depth of 5 feet bgs (with the exception of SB-5) in each location after clearing the site of underground utilities. A total of five boreholes (SB-1 through SB-5) were advanced. The Ld locations are shown on the Site Map (Figure 2). The boreholes were drilled with an AMS PowerProbe DPT/HSA rig. The PowerProbe rig L has the advantage that if direct push conditions meet refusal, then the rig can be converted to hollow stem auger operation. This was case in the first boring, SB-3, located adjacent to the former dispenser island. The direct push rods met refusal at approximately 45 feet bgs and groundwater had not yet been encountered. The rods were removed and the hole was re- drilled to 45 using hollow stem auger. The direct push rods were then used again to continuously core from 45—60 feet bgs. This was the only hole in which augers were used. V In GTI work plan we proposed two borings to the east of the UST location. Unfortunately, there was not enough room between the UST and the site building to place the boreholes in these locations. Placing the boreholes in the building was not an option due to the lack of space to move the drill rig. Therefore, a single slant boring, SB-5, was advanced just east of the UST at a 45° angle underneath the front of the building at the site. The boreholes were filled with a neat cement grout after sampling was completed. 2.1.1 Soil Sampling Procedure The PowerProbe advances a coring tool with a pneumatic hammer to a selected depth. Upon reaching that depth the coring tool is opened and advanced further to fill the core barrel. The �. soil sample enters an acetate cylinder contained in the coring tool. Upon filling, the coring tool is pulled from the hole and the cylinder is removed. The cylinder is then cut and the selected interval is capped with Teflon end caps, labeled, and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. The sampling technician wore disposable gloves while collecting all samples. The remainder of the soil is used for geologic logging. A boring log providing sediment description using the USCS and field observations was maintained by a professional geologist working under the supervision of a registered geologist. L..