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ENVIRONMENTAL COST MANAGEMENT,INC. 3525"Ild Avenue,Suite 2DO Costs Massa.California 02026 October 21,2009 RBCEEIE0 o Margaret Lagoriv San Joaquin County Environmental Health Department OCT 2 3 2009 600 East Main Street Stockton,CA 95202 ENVIRONMENT HEALTH RE: Vapor Extraction Well Decommissioning PERMIT/SERVICES Former Nestl6 USA, Inc. Facility 230 Industrial Avenue Ripon,CA 95366 Dear Ms.Lagorio: On behalf of Nestle USA, Inc. (Nestl6), Environmental Cost Management, Inc. (ECM) has prepared this letter to notify San Joaquin County of ECM's intent to properly decommission eight vapor extraction(VE) wells at 230 Industrial Avenue in Ripon, California. The eight wells proposed for decommissioning are depicted on the enclosed Figure 1, as are 3 wells that can no longer be located. Also enclosed with this letter are eight Well Permit Applications for Destruction. Table I superimposed on Figure 1 summarizes the construction details for the wells. Between 1998 and 1999,twelve vapor extraction wells were constructed at various locations(see Figure)to remediate the vadose zone soil impacted with trichloroethylene (TICE). The wells were installed in several phases,with the last vapor extraction activities conducted between 1999 and 2001. Since 2001,none of the vapor extraction wells have been in use with the exception of VE-6, which has been incorporated into the on-going groundwater monitoring program. Since the remaining vapor extraction wells are no longer in use, Nestle desires to properly decommission those wells that can be located. Therefore, Nest16 intends to destroy these wells,as discussed below. The Standards for Well Construction&Destruction in San Joaquin County(San Joaquin County Ordinance Code Section 9-1115.6), Subsections 6.3 and 13.17 identify the requirements for sealing wells which no longer function as originally designed. The eight wells for which applications are being submitted are shallower than 100 feet below ground surface (bgs). Five of the wells (VE-2 and VE-7 through VE-10) contain no standing water,nor do they come in contact with groundwater. These wells will be destroyed as required in subsections-63.4 and 6.3.6 bffhe County Ordnance Code. Two of the wells (VE-1 and VE-3) contain groundwater, which is at a depth of approximately 29 feet bgs. These wells will be destroyed as required in subsection 13.17,1 such that they cannot produce water, nor act as a vertical conduit for the movement of groundwater. The final well(VE-5)will need to be assessed at the time of decommissioning, as a 2-inch sleeve inside the 4-inch PVC screen is blocking access and preventing a depth sounding. If this well contains water, it will be destroyed per the requirements of the County(subsection 13.17), such that it cannot act as a conduit to groundwater.