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• • <br /> PARSONS <br /> 2121 North California Boulevard, Suite 500•Walnut Creek, California 94596•(925) 941-3700•Fax: (925) 979-9781 •www.parsons.com <br /> November 24, 2003 <br /> Ref: 440269 <br /> California Regional Water Quality Control Board <br /> Central Valley Region U1 Y <br /> 3443 Routier Road, Suite A <br /> Sacramento, California 95827-3003 NOV 2 6 2003 <br /> Attention: Mr. Gerald J. Djuth ENVIRONMENT HE, <br /> PERMIT/SERVICE. <br /> Subject: Modified Location of Monitoring Well <br /> Applied Aerospace Structures Corporation <br /> Stockton, California <br /> Dear Mr. Djuth: <br /> In a letter dated 25 September 2003, the Regional Water Quality Control Board <br /> (RWQCB) conditionally approved the Work Plan submitted by Parsons on 23 October for <br /> installation of a monitoring well offsite and downgradient of monitoring well MW-5R. <br /> The conditions for approval were that the proposed well be moved northeastward to a <br /> position "midway within the arc formed by the fall and spring gradient directions" and <br /> that a revised site map showing the new location should be submitted by 26 November. <br /> The well location has been revised as indicated on the attached Figure 1. An annual <br /> average gradient direction was judged to be a better representation of travel path than the <br /> direction of annual maximum gradient. Therefore, seasonal gradient directions were <br /> estimated during two representative annual periods: <br /> Gradient Direction <br /> Month of Gradient Estimate (Relative to Site North) <br /> (0) <br /> Jun-98 100 <br /> Aug-98 140 <br /> Nov-98 114 <br /> Jan-99 96 <br /> 1998 average'` 113 <br /> 7-Nov-02 95 <br /> 10-Feb-03 97 <br /> 5-May-03 100 <br /> 11-Aug-03 115 <br /> 2003 average 3 102 <br /> 1 Site North(fence line parallel to So. Airport Way)is—15 degrees west of true north. <br /> 2 Source- 1998/99 quarterly reports just after regional groundwater recharge event and prior <br /> to initiation of remedial pumping <br /> 3 Source—Figures 2 through 5,2003 Annual Report(Parsons 2003b) <br /> LED <br />