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P.O. Box 576981 M.J. Kloberdanz & Associates Modesto, California 95357-6981 Environmental Assessment Phone: (209) 577-8186 Fax: (209) 577-8158 no 1"1V September 19, 2006 Ms. Lori Duncan San Joaquin County $Ep 2 Environmental Health Division T HEALTH P.O. Box 2009 ENVIRONMENT Stockton, California 95201RMI ERVICES RE: Well Destruction: Pombo Ranch at 2410 Lammers Road, Tracy, California On September 12, 2004 M.J. Kloberdanz & Associates contracted the licensed drilling company (C57-720904) V&W Drilling, Inc. to estroy the six groundwater monitoring wells at the above referenced facility. The deep well, MW-105 at 40 feet bgs, was pressure grouted according to San Joaquin Counly Environmental Health Division "Well Standards" Section 13.17. REQUIREMENTS FOR DESTROYING MONITORING WELLS AND EXPLORATION HOLES: • The monitoring wells shall be investigated to determine its condi ion and details or its construction prior to its destruction. • The well shall be sounded immediately before it is destroyed to determine whether there are obstructions that will interfere with filling and seating. • Any obstructions found in the well or boring shall be removed before filling and sealing operations begin. • The sealing material shall be placed under pressure to ensure that the monitoring well is properly filled and sealed. • Casing material may require perforation,or puncturing,to allow or proper placement of sealing materials. • The wells shall be tilled by use of a tremie pipe or equivalent,proceeding upward from the bottom of the well or boring. • Seating materials shall be placed in one continuous operation unl ss conditions in the well or boring dictate that sealing operations be conducted in a staged manner and prior approval is obtained from the Director. + Pressure required for the placement of sealing material shall be maintained long enough for sealing materials to properly set. • Verification shall be made to determine that an adequate seal has been installed by an EHD representative. • 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 3 feet below the ground surface,and the well casing shall then be cut off 6 inches above the bottom of this excavation and removed. • The grout used to fill the well shall be allowed to spill over into tic excavation,during the sealing operation,and fill it for a thickness of one foot and form a"cap"which has a diameter of a least one foot greater than the diameter of the originally drilled hole. • After the sealing operation and the sealing material have set,the excavation shall be filled with clean soil. Approximately 18 gallons, 4071 cubic inches, of a 4-bag mix of cement was used for well MW-105. Calculations indicate that about 4963 cubic inches of cement would completely have filled the 7 feet of screen pack and 40 feet of well casing if the there was no sand in the screen pack. Monitoring well MW-5 was completely drilled out to remove the casing and screen pack and then filled with cement using the augur to conduct the cement to the bottom of the boring.