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Goofogua(T"echnwi Inc Page 2 ' Srte Charactejization Report Valentine(Castle Motors) Protect No 723 2 Navembek 30,2001 ' 2.0 SCOPE OF INVESTIGATION 2.1 Soil Boring Installation ' One borehole (MW-201) was drilled to a depth of 155 feet below grade (bgs) From previous drilling projects at the site, we knew that heaving sands became a problem starting at 70 feet bgs Therefore, this borehole was drilled with a combination of hollow stem auger & mud rotary drilling The drill rig is owned and operated by V&W Drilling (C57# 720904) from Rio Vista, California ' The following procedure was used to drill the borehole On October 22, 2001, a set of 10- inch hollow stem augers were drilled down to a depth of approximately 50 feet A six-inch inside diameter steel casing was placed in the boring to provide a return conduit for the drilling mud and to isolate the drilling mud from the heavy contamination in shallow soil ' The annular space around the casing was filled with grout utilizing a tremmie pipe and allowed to set overnight On the following day, October 23, 2001, the water that had infiltrated into the steel casing was purged Once this water was removed a 5-inch diameter ' mud rotary drill rod/bit was lowered down the inside of the steel casing and the drilling progressed The drilling process was slow due to inud circulation problems and clay clogging the drill bit The borehole was advanced from 50 feet bgs to approximately 108 feet bgs on day two of the drilling project No soil samples were collected from 50 to 108 since we had drilled SB-201 in 1999 and sampled through this interval Soil sampling started at 108 feet bgs at 9 15 AM on the morning of day three, October 24, 2001 The final depth of 155 feet bgs was not achieved until 9 00 P M on day three The monitoring well was installed on October 25, 2001 ' Monitoring well permits were secured from the San Joaquin County Public Health Services/Environmental Health Department (SJC PHS/EHD) The local regulatory agency was notified 48 hours prior to commencing work Soil cuttings and drilling decontamination water were placed in DOT-17 approved 55 gallon drums and stored on site until their disposal can be arranged ' 2.1 1 Soil Sampling Procedure Due to its proximity to previous boring MW-101 and SB-201, soil samples were collected ' for geological evaluation starting at 108 feet bgs in MW-201 A boring log providing sediment description using the USCS and field observations were maintained by a professional geologist working under the supervision of a registered geologist Soil samples were collected in 6 0-inch brass liners using a 2 0-inch modified California split spoon sanlipler All soil samples were sealed with Teflon sheets, capped with plastic end caps, labeled, and placed in a cooler at 4° Celsius for tiansport to the laboratory following Chain of Custody protocol It was planned to use an OVM for field screening, but the device malfunctioned and was inoperable on October 24, 2001 Attempts were made to continuously sample the borehole but this was not possible Starting at 111 feet bgs, a combination of drilling mud and formation clay clogged the sampling tool An attempt was made to use the SimulProbe'Tool to collect soil and soil-porewater samples starting at 127 feet bgs A soil sampled was retained in the tool, however clay