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Lodi NPA Participant Group -2 - June 26, 2006 south of Phase I Borings B-1 and B-2, to the southeast of the LNPA, and to the east of Boring B-3. It is proposed in this Addendum to first investigate the southern extension of the LNPA- by NPAby drilling boring B-6, approximately 1,250 feet south of B-1. An exploratory boring to collect lithologic and geophysical data, and a separate boring to collect depth discrete water samples will be conducted to about 450 feet below ground surface. Staff concurs with this proposal as a good first step in further evaluating the lateral and vertical extent of contamination. However, additional investigation will be needed in the near future to continue to define the extent of the LNPA. In addition, please provide a response explaining why the step-out location was chosen at a distance of about 1250 feet to the south. Finally, if access cannot be obtained for B-6 location as proposed, the next choice of location should moved in a northerly direction towards the Phase I B-1 location, not further away from the B-1 location. Staff understands the Participants desire to ensure definition of the southern extent of the plume. However, we are concerned that non-detectable VOC results that far to the south could create more unknowns. In summary, staff concurs with the next step in the LNPA RI as proposed. However, we encourage the Participants to consider a location closer to the existing data points at B-1 and B-2. Finally, we look forward to receiving additional scope of work to further investigate the LNPA. If you have any questions or comments, please contact Marie McCrink at 916-464-4816, or by email at mtmccrink(@-waterboards.ca.gov. I Marie McCrink, P.G., C.H. Associate Engineering Geologist Private Sites Cleanup Unit cc: Mr. Marc R. Lombardi, Geomatrix Consultants, Inc. Rancho Cordova Ms Mande Lauenroth, Geomatrix Consultants, Inc. Rancho Cordova