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Geo(o a(Techntcs 7ne Page 2 Sof&, Groundwater Investigation Report Ted Peters -AST . Project2 App it 20,,2 200101 groundwater samples were also analyzed for gasoline oxygenates (MTBE, TAME, TBA, DIPE and ETBE), 1,2 DCA, and EDB utilizing EPA Method 8260B ' The Geoprobe effort resulted in the completion of the lateral definition of the soil plume Gasoline range hydrocarbons detected in soils on the western portion of the site are anomalous and not consistent with the two known sources of petroleum fuels at the facility Diesel range petroleum hydrocarbons and gasoline oxygenates were not detected in any of the groundwater samples from the probe locations Based on the Geoprobe effort, GTI proposed two new monitoring wells one shallow well to ' be placed in the vicinity of the highest level of detected gasoline contaminants in the west portion of the site, and one deep well to be placed in the central portion of the site near the presumed source area of the diesel In his December 26, 2000, correspondence, Mr Joseph 1 Mello of the Regional Watei Quality Control Board (RWQCB) denied the deep well and requested a second shallow well in the southwest portion of the site ' 2.0 SCOPE OF INVESTIGATION The purpose of this work was to install the two shallow groundwater monitoring wells per ' the RWQCB directive On March 21, 2001, Geological Technics Inc (GTI) supervised the installation of two new monitoring wells, MW-7 & MW-8 ' 2.1 Soil Boring Installation A monitoring well permit was secured from San Joaquin County and the agency was notified 48 hours prior to commencing work The subsurface was cleared of underground utilities by notifying Underground Service Alert and by consulting with the property owner The soil borings for the wells were drilled to a depth of 20 feet bgs with an 8-inch outside ' diameter (o d ), continuous flight, hollow stem auger owned and operated by V&W Drilling (C57# 720904) Soil samples were collected as described in Section 2 1 1 These borings were converted into 2-inch diameter monitoring wells Contaminated soil cuttings and drilling decontamination water were placed in DOT-17 55- gallon drums and placed alongside the building until disposal can be arranged 2.11 Soil Sampling Proeedure Soil samples were collected for geological and analytical evaluation at five-foot intervals A professional geologist working under the supervision of a registered geologist maintained ' a boring log providing sediment description using the USCS and field observations Soil samples were collected in 6 0-mch brass liners using a 2 0 inch modified California split spoon sampler All soil samples were sealed with Teflon sheets, capped with plastic end caps, labeled, and placed in a cooler at 4° Celsius for transport to the laboratory following ' Chain of Custody piotocol 1