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Geologcca!Technics Inc Page 5 ' Soil and Groundwater Inxesttgation Work Plan Cardoza(Main 5t) . Protect No 662 2 January 17,2003 32 Monitoring Well Installation IThe construction of the water table wells (MW-RI, -R2 & -R3) to replace existing wells MW-1 through MW-3 and shallow well MW-4 are outlined in the table below Well o Dia creep Slot Sand Packrani Grout Seal Seal --MW--l-R7---T'7317— - san 22'-surface MW--21U2"t31-'——2 315 0 10 X12 sande-24=3-1-'– 22 224' 22'-surface - R 2"7316--TI' sand -sur ace 22'-sur ace Wells MW-1R, MW-2R, MW-3R & MW-4 will be two inch (2 inch) diameter using schedule 40 PVC casing with flush threads The screened intervals are designed to intercept ' first groundwater at the historical depths as indicated in Table 1- Summary of Groundwater Elevation and Gradient Before installing the bentonite seal the wells will be surged using a clean surge block 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 The transition seal on deeper wells will consist of weighted bentonite pellets 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 4% bentonite) through the augers, as they are withdrawn to ensure that an integral grout seal is achieved The wells will be secured with locking watertight caps encased in flush mounted traffic rated well boxes The monitoring wells in the locations of CPT borings CPT-5, CPT-6, CPT-7 and CPT-8 will ' be constructed utilizing CMTTM technology CMTTM allows groundwater sampling from multiple depths from a single borehole installation The CMTTM system information is included in Appendix C The CMTTM wells will have screened intervals based on the ' results of the CPT boreholes These details will be submitted in an addendum to this report prior to well installation Soil boring permits will be secured as necessary and the local regulatory agency will be ' notified 48 hours prior to commencing work The subsurface will be cleared of underground utilities by notifying Underground Service Alert ' The boreholes for the monitoiing wells will be drilled using an 8-inch outside diameter, continuous flight, hollow stein auger owned and operated by V&W Drilling (C57# 720904) 3.3 Monitoring Well Development After the well sealing materials have set (>24 hours) all of the new wells will be developed (using mechanical surging and pumping methods) until a clear stream of water is obtained The wells will be purged and groundwater samples collected after well development All development and purge water will be containerized in 55 gallon DOT approved containers and stored on site until their disposition can be arranged i