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cwtogtcal reclmaW Page 5 Feasibility Study&Investigation Work Plan Cardoza(Main St) Project No 662 2 Apn1 19,2004 ' • Benzene, Toluene, Ethyl Benzene and Xylene (BTEX) by EPA method 8020 Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 5030/8015(M) ' • Total Petroleum Hydrocarbons as Diesel (TPH-D)by EPA method M8100 • Oxygenated Fuel Compounds (MTBE, DIPE, ETBE, TAME & TBA) by EPA method ' 8260 • 1,2 DCA, EDB and ethanol by EPA method 8260 • Methanol by EPA method 8015 ' + Lead by method 6010 ' 3.0 SOIL VAPOR/GROUNDWATER EXTRACTION WELL Extraction well EW-1 was installed on December 12, 2003 to facilitate an aquifer pumping test But unfortunately the screened interval of this well (37 -- 50 feet bgs) will not allow vapor extraction to address shallow soils at the site GTI proposes installing a second soil ' vapor/groundwater extraction well to address the shallower residual soil contamination beneath the former UST excavation ' 3.1 Extraction Well Installation A soil vapor/groundwater extraction well, EW-2, will be placed in the former UST excavation Figure 5 includes the proposed well boring location Prior to commencing work, soil boring/monitoring well permits will be secured and the SJC/EHD will be notified 48 hours in advance The subsurface will be cleared of underground utilities by notifying Underground Service Alert ' The boring will be drilled using a 10-inch outside diameter continuous flight hollow stem auger and will be advanced to a depth of 32 feet below the ground surface (bgs) The extraction well will be constructed using schedule 40 PVC casing with flush threads ' Before installing the bentonite seal the well will be surged using a clean surge block or bailed with a steel bailer to achieve maximum filter pack density A granular bentonite transition seal will be installed above the sand filter pack and hydrated with clean tap water A surface seal will be achieved by pumping a neat cement grout (augmented with < 4% ' bentonite) through the augers, as they are withdrawn to ensure that an integral grout seal is achieved The well will be secured with locking watertight cap and encased in flush mounted traffic rated well box Soil cuttings will be containerized in DOT approved 55- gallon steel drums and held on site pending disposal This well will be constructed as outlined in the table below ' —Well No. ia. creen of an ac rans. rout Seal Seal M--sand - - 18'-surface Screen Selection Rationale Figure 6 is a cross section of the subsurface on a southwest-northeast trend across the site ' Proposed extraction well EW-2 has been projected onto the cross section in the vicinity of the former UST excavation (proposed monitoring well MW-5 is also shown on the right side of the diagram near CPT-7) The screened interval of the well will just penetrate the groundwater table that was recorded at approximately 29 feet bgs in November 2003 Once