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September 29, 2014 Monitoring Well Abandonment and Installation Workplan procedure will be employed to destroy and seal the monitoring wells and piezometers that are approved for abandonment. Per San Joaquin County Well Standards,monitoring wells will be destroyed by a C-57 licensed contractor under the direction of a California Registered Professional Engineer, California Professional Geologist,or a California Certified Engineering Geologist.All work shall be performed in accordance with San Joaquin County Well Standards.After receiving approval from RWQCB staff,the following requirements pertaining to destroying monitoring wells will occur. • Obtain well destruction permits from the San Joaquin County Environmental Health Department(SJCEHD). • Schedule well destruction inspections with the County and perform all sealing operations in the presence of a County inspector,unless directed otherwise by the County. • Before destruction,sound well to determine whether there are obstructions that could interfere with filling and sealing.Obstructions found in the well or boring shall be removed before filling and sealing operations begin. • The wells and piezometers will be destroyed by removing all material within the original borehole including the well casing,screen,filter pack and annular seal. Material to be extracted from the original borehole will be removed by means of drilling,including over-drilling if necessary.The excavated well boring shall be filled with sealing materials by use of a tremie pipe or equivalent,proceeding upward from the bottom of the well or boring.Sealing materials shall be placed in one continuous operation,and the pressure required for the placement of sealing material shall be maintained long enough for sealing materials to properly set. If site conditions do not allow for full removal of all material,the well casing will be left in place during sealing operations.A hole at least one foot larger in diameter than the originally drilled hole shall be excavated around the outside of the well casing to a depth of three feet below the ground surface,and the well casing shall then be cut off six inches above the bottom of this excavation and removed.The grout used to fill the well shall be allowed to spill over into the excavation during the sealing operation,and fill the excavation up to a thickness of one foot forming a "cap"which has a diameter of at least one foot greater than the diameter of the originally drilled hole.After the sealing operation is completed and the sealing material has set,the remaining excavation shall be filled with clean soil. • Sealing material will be selected based on the required structural,handling,and sealing properties,and the chemical environment into which it is placed. Sealing materials shall have such low permeability that the volume of water passing HydroFocus, Inc. 11