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Ms. Amy Terrell <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> August 13, 2007 <br /> Page 2 <br /> Task 5 —Quarterly Groundwater Monitoring (four quarters, includes newly installed <br /> wells): by August 31, 2007; November 30, 2007; February 29, 2008; and <br /> May 31, 2008 <br /> Task 6—Groundwater Investigation Report: by October 31, 2007 <br /> Task 7 Groundwater Monitoring Reports: by October 31, 2007 (included with the <br /> groundwater investigation report); January 30, 2008; April 30, 2008; and <br /> July 31, 2008 <br /> Task 1 has been completed, and Task 2 has been substantially completed. The four existing on- <br /> site groundwater monitoring wells were sampled on July 13, 2007. Downgradient groundwater <br /> sampling was conducted from July 25 to 27, 2007. <br /> Based on the results from Tasks 1 and 2,UniFirst has expanded the scope of Task 2. This <br /> expansion will necessitate revisions to the estimated schedule presented previously. The scope <br /> changes and proposed revised schedule are presented in the following sections. <br /> PROPOSED REVISIONS TO THE WORK PLAN <br /> The objective of Task 2 is to characterize the nature and extent of VOCs in groundwater from the <br /> site. To meet this objective, Geomatrix used the direct-push boring method to collect discrete- <br /> depth groundwater samples and analyzed the samples using an on-site mobile laboratory. As <br /> analytical results were received, they were used to guide the location and depth of subsequent <br /> groundwater sampling. Prior to collecting the discrete-depth groundwater samples, the <br /> hydrostratigraphy and potential sample target zones were identified using cone penetration <br /> testing(CPT). <br /> CPT data were collected to a maximum depth of 90 feet below ground surface (bgs) at two <br /> locations, and discrete-depth groundwater sampling was conducted to a maximum depth of <br /> 90 feet bgs at six locations. A total of 16 discrete-depth groundwater samples were collected and <br /> analyzed for VOCs by the on-site mobile laboratory. <br /> Based on the data from the on-site mobile laboratory, we plan on extending the investigation to <br /> include additional groundwater sampling locations off site and soil vapor sampling on site. <br /> The additional groundwater sampling locations must be permitted with the City of Stockton and <br /> San Joaquin County. Also,we may drill to depths beyond the capacity of the direct-push <br /> C:\Documents and Settings\minfurna\Local Settings\Temporary Internet Fi1es\0LKI\13290-04.doc <br />