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i S E C 0 R <br /> advanced vertically A fast recharge rate was observed, creating an increasing volume of water <br /> that was expelled as the borehole was advanced Although total depth was achieved using this <br /> drilling method and a well was created, SECOR concluded that an alternate drilling method was <br /> necessary for the remaining two monitoring wells to reduce the amount of soil cuttings and <br /> Purge water <br /> All soil cuttings generated during the installation process were stored in a 15-cubic yard capacity #� <br /> roll-off bin, located onsite All purged groundwater that was removed from the borehole was <br /> stored in a 6,500 gallon capacity poly tank, located onsite <br /> 342 Sonic Drilling Method <br /> s, <br /> Between April 11 and April 15, 2005, Cascade installed MW-16 and MW-17 using the sonic <br /> ' drilling method The wells were installed to depths of 120 feet bgs (MW-16) and 121 feet bgs l <br /> (MW-17) and were constructed of 4-inch diameter schedule 40 PVC casing with a 10-foot , <br /> 0 020-inch slotted screen interval Field procedures are included in Appendix D U <br /> Groundwater was first encountered at 57 feet bgs in MW-17 and at 69 feet bgs in MW-16 Both Y <br /> wells achieved a static water level of approximately 34 feet bgsr <br /> ' All sod cuttings generated during the sonic drilling process were stored in Department of <br /> Transportation (DOT) approved 55-gallon drums that were staged onsite Drilling equipment y <br /> was steam-cleaned in between boreholes and all rmsate water was stored in DOT approved 55- } <br /> gallon drums as well " <br /> 35 Soil Selection and Analysis <br /> ' As per SECOR's Work Plan for Well Installation dated August 12, 2004, soil samples were a <br /> collected at ten-foot intervals from 80 to 120 feet bgs from the borehole for MW-17 MW-15 and <br /> MW-16 required no sampling due to previous site assessment work done in the immediate ,f <br /> ' vicinity of these two wells %g A <br /> t� <br /> All sod samples were submitted to a California certified lab under chain-of-custody protocols and <br /> analyzed for the presence of TPHg, BTEX, TBA, MtBE, DIPE, EtBE, TAME, 1,2-DCA, ethylene <br /> EDB, and ethanol by EPA Method 82608 SECOR requested Severn Trent Laboratories (STL) <br /> analyze for TPHg, but their report lists this analyte as Gasoline Range Organics, C6 through <br /> C12 range (GRO (C6-C12)) A certified laboratory report with chain-of-custody documentation is <br /> included in Appendix E <br /> ' 36 Monitoring Well Development <br /> On April 20, 2005, SECOR field staff observed Cascade during development activities for MW- <br /> 15, MW-16 and MW-17 All three monitoring wells were mechanically surged to clean the <br /> i screen interval of fine-grained material One hundred and eighty gallons of groundwater were ; <br /> purged from MW-15, 300 gallons of groundwater were purged from MW-16 and 660 gallons of <br /> groundwater were purged from MW-17 All purged groundwater was stored in DOT approvedi, <br /> 55-gallon drums and staged onsite Field procedures for well development are included in a <br /> Appendix D and Well Development Logs are included in Appendix C <br /> f <br /> Updated SCM 2005 doe 7 <br /> 17CP 64409 05 0005 <br /> f{�I <br /> 4 <br />