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LIGHT, AIR & SPACE CONSTRUCTION ENVIRONMENTAL SERVICES COMPANY State Contractor's License Number 445403 State EPA R_E.A.Number 04072 An EHD representative had reviewed this proposed work (soil excavation, surface treatment and groundwater monitoring well installation) in their letter dated February 28, 2006. The EHD comments regarding the proposed monitoring wells indicted that three wells would be sufficient for this phase of work. This work plan presents the work plan for the installation for the three groundwater monitoring wells and initial quarterly monitoring for this site. 2.0 Technical Approach LA&S will build on the previous environmental work conducted at the subject site. We propose to drill three (3) soil borings to depths of about 30 feet below the ground surface (bgs) into the aquifer and either terminated in the underlying Gay aquitard if present, or advanced a maximum of ten feet into the uppermost groundwater aquifer. Three wells will be installed at the following locations: one monitoring well adjacent at each former underground tank pit; and one in the assumed down-gradient direction beyond .the former tank pits (see Figure 2). Regional information from the San Joaquin County Flood Control and Water Conservation District indicates that groundwater at the site vicinity is estimated to flow generally in a northwesterly direction and groundwater occurs at a depth of 10 to 20 feet below the surface. The three (3) borings will be converted to groundwater monitoring wells. Soil sampled will be obtained at five-foot intervals of depth from each boring for soil lithology logging and selected soil samples will be retained for chemical analysis. The borings converted to the three groundwater monitoring wells will be developed, purged and sampled. The groundwater wells to measure long-term groundwater flow direction and sample collection for quarterly sampling. This data, together with the previous site work, will be used for presentation for site closure review to EHD following at least one year of groundwater monitoring. 3.0 Field Methods - Exploratory Borings Three (3) exploratory borings will be drilled at the locations shown on Figure 1. Drilling and well installation permits will be secured from the EHD permits and an underground utility clearance will be performed prior to doing the fieldwork. A site safety plan will be prepared for the site work The boreholes will be drilled with a truck-mounted hollow-stem auger rig. All drilling equipment and sampling tools will be cleaned prior to arriving, and before leaving the site. The decontamination process will use a tri-phosphate soap to wash the soil sampler between each sample run and each borehole. Augers and drill rods will be decontaminated in similar fashion between each borehole using a pressure washer as needed to remove soil/sediment adhering to the augers, rods and drill bits. The hollow-stem augers will be advanced and discrete soil samples will be collected at five-foot depth intervals from each borehole. The augers and drill rod will be advanced to the desired sampling depth interval, and a drive split spoon sampler was driven ahead of the drill bit. The soil samples will be sealed with Teflon paper and plastic endcaps, labeled, logged onto chain-o#-custody forms and place in a chilled ice chest on crushed ice for transport to a State certified analytical laboratory. PaL3re2of5 MAIN OFFICE • 1707 LITTLE ORCHARD STREET, Surm A•SAN JOSE• CA•95125 MAmiNG ADDREss•P.O.Box 36303 •SAN JOSE•CA•95158-6303• 4081979-0661 oFFIcE-408/979-0621 FAx-408/640-2899 CELL PHONE-DGUTil[RIDGE@LIGHTAIRANDSPACE.COM E-MAIL GENERAL AND ENGINEERING CONTRACTOR•HAZARDOUS SUBSTANCE REMOVAL CONTRACTOR•SITE ENviRoNMENTAL ASSEsshENTS WETLAND AND RIPARIAN HABITAT—AssusNmNT—DESIGN—RESTORATION—CONSTRUCTION—MTTIGATiON MONITORING