Laserfiche WebLink
i <br /> ARCADES Ms. Lori Duncan ;' <br /> J'anurary 10, 2012 <br /> sampling event; therefore,the concentrations from the'fourth quarter 2010 event <br /> were evaluated when considering the destruction method for the remaining site wells <br /> (Table 2). <br /> Pressure Grouting, Excavating and Casing Removal <br /> Groundwater monitoring wells MW-2, MW-3 and MW-7 will be destroyed by <br /> removing the well box at each well and tremie grouting neat cement into the well <br /> casing from the total depth of the well to ground surface to displace zgroundwater in <br /> the well casing. Following grouting, pressure will be applied to each well ensuring a <br /> complete seal of the screened interval. Subsequently, an area one foot larger in <br /> diameter than the original borehole will be excavated around the outside of the well <br /> casing to a depth of 3 feet below ground surface (bgs) per San Joaquin County <br /> requirements. The well casing will then be cut off 6 inches above the bottom of the <br /> excavation and removed.Additionsl grout will be added as needed to obtain a <br /> mushroom cap. The borehole will be backfilled with grout to just below the surface. <br /> Surface grade will be completed to match existing conditions at each well location. <br /> Well construction details are included in Table 1. <br /> Over-drilling to Depth <br /> Groundwater monitoring wells MW-1, MW-4, MW-5, MW-6, and MW-8 through ' <br /> MW-13 and ozone injection wells IWA through IW-5 will be destroyed by removing <br /> the well box at each well and over-drilling each well to their respective total depths <br /> using a drilling rig equipped with 10-or 12-inch outside diameter(OD) hollow stem <br /> augers depending on the diameter of the original boring. Neat cement grout will be <br /> tremie piped from the total depth of the well to approximately 3 feet below surface <br /> grade. The borehole with be backfilled with grout from 3 feet bgs to just below <br /> surface grade. Surface grade will be completed to match existing conditions at each <br /> well location. <br /> Well construction details are included in Table 1. . <br /> Investigation Derived Waste <br /> x- <br /> Soil cuttings produced during drilling, displaced groundwater discharged during <br /> grouting, and water generated during steam cleaning will be containerized in 55 <br /> gallon drums and temporarily stored on the site pending characterization and <br /> Page: <br /> (IVpiojecAfNvlMcntWM oelivamieslWaRPmmwelID.*& ACAtM t2011DEP wed D-b-tm Wwk Plan,do iii 374 <br /> a <br /> y <br /> • �i <br /> c C <br />