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Michael J.Infuma <br /> 06/05/2006 <br /> Page 2 of 3 <br /> What Type of Soil Vapor Point will be used and how will they be installed and destroyed? <br /> Direct push soil vapor probes can be installed more quickly and cost effectively than augered <br /> installations. In addition, disruption of the subsurface is minimized, resulting in a shorter required re- <br /> equilibration time prior to soil vapor sampling. Therefore, BBL has selected the direct-push soil vapor <br /> sampling probe (implant type) as detailed in Section II, Subsection B1 of Chevron's Soil Vapor Sampling <br /> Tool Kit Version 1.4 for the proposed nine deep and four shallow vapor probes. <br /> To install the probes, a direct-push drill rig will be used to advance a series of drive rods to within one <br /> foot of the water table(approximately 7 feet bgs)in each of the nine proposed deep locations and at 1 foot <br /> bgs at each of the four proposed shallow locations. When the targeted depth is reached the probe will be <br /> slid down the bore of the drive rods and attached to the drive point at the bottom. As the rods are <br /> removed, a sand pack will be placed around the probe followed by a hydrated bentonite seal extending to <br /> ground surface. A copy of Chevron's Soil Vapor Tool Kit is provided as Attachment 1 of this letter. <br /> At the completion of testing,the nine deep soil vapor sample probes will be destroyed in accordance with <br /> San Joaquin County Requirements and with Bulletin 74-90, California Well Standards, California <br /> Department of Water Resources, June 1991. The vapor sampling points will be destroyed by drilling out <br /> and removing all material within the original borehole. The boreholes will then be grouted from the total <br /> depth of the borehole to ground surface using a tremie pipe and cement-bentonite grout. The four shallow <br /> probes will be excavated and removed. <br /> If you have any questions or comments regarding the contents of this letter,please contact either David <br /> Lay of BBL at(315)671-9197 or David Evans of BBL at(916) 857-0124, extension 226. <br /> Sincerely, <br /> BLASLAND,BOUCK&LEE,INC. <br /> David W.Lay,C.P.G. Michael P. Fleischer,P.E. FEssi <br /> Senior Geologist Principal Engineer QRo n <br /> FL, Fyc <br /> DME/ rP y 2 <br /> Z <br /> U 657.05 � A <br /> Enclosures: * EXP' 9 L <br /> CiW- <br /> Figure 1 Generalized B-zone Monitoring Well Construction �Tt'C rpt FOQ <br /> Figure 2 Generalized C-zone Monitoring Well Construction <br /> Attachment 1 Chevron's Soil Vapor Sampling Technical Toolkit(Version 1.4) <br /> 001603054_95045 Response W Com nN.dm <br />