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EL) <br /> DEC X 7 2007 <br /> GROUND ZERO ANALYSIS, INC. �NVlpNMENrEALTH ` <br /> 1714 Main Street Y,u�� <br /> Escalon, California 95320-1927 ` <br /> Telephone: (209) 838-9888 JV/ <br /> Facsimile: (209) 838-9883 <br /> December 14, 2007 <br /> James L.L. Barton, P.G. <br /> CA Regional Water Quality Control Board, <br /> Central Valley Region <br /> 11020 Sun Center Drive#200. <br /> Rancho Cordova, CA 95670-6114 <br /> Subject: Letter Revision—Workplan for Groundwater and Soil Gas Investigation <br /> 1855 Jackson Avenue,Escalon, CA j <br /> Dear Mr. Barton: <br /> This letter is in response to your document review letter dated December 13, 2007. The document <br /> review letter approves the September 2007 Workplan for Groundwater and Soil Gas Investigation <br /> (Workplan) submitted by Ground Zero Analysis, Inc(Ground Zero)with three'conditions. <br /> 1. Please include at least three (3)additional soil gas sample locations at the former tank pits... <br /> a. Ground Zero.has modified the figure showing the soil gas survey locations to include an <br /> additional three (3) sampling points. A revised map showing.the additional sampling <br /> locations is attached as Figure 4. <br /> b. The additional sampling points will be sampled and analyzed using the same protocol <br /> outlined in the September 2007 Workplan. <br /> 2. USEPA Method 8260B provides for all of the above constituent with better detection limits... <br /> a. Ground Zero will modify the groundwater sample analyses using the following methods: <br /> • TPH and TPHd by EPA Method 8015M <br /> • Benzene,toluene,-ethylbenzene, and xylenes(BTEX)by EPA method 8260B <br /> • Fuel Oxygenates(MtBE,DIPE, ETBE, TAME, and TBA)by EPA method 8260B <br /> • Lead Scavengers(EDB and 1,2-DCA)by EPA method 8260B <br /> • Dissolved Lead by EPA method 6010/200.7. <br /> 3. There is a question whether mobile labs are capable of reaching adequate lower soil gas sample <br /> detection limits... <br /> a. I have contacted Mark Jerpbak with TEG Northern California, Inc. located at 11350 <br /> Monier Park Place, Rancho Cordova, CA 95742 and have been assured that the mobile lab <br /> can meet TIERI detection limits. As an example the laboratory detection limit for benzene <br /> is 0.080 µg/L. Feel free to visit the,project site during the investigation, contact Mr. Jerpbak <br /> at(916) 853-8010, and/or visit the TEG website at www.tegenv.com. <br /> G:\GROUNDZE\GONZALES\Reports\Work Plans\Letter Revision to 0709 WP 071214.doc <br />