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Pagel of 2 <br /> Harlin Knoll [EH] <br /> From: Robert Ellgas [rellgas@msegrp.com] <br /> Sent: Monday, March 17, 2008 4:35 PM <br /> To: Harlin Knoll [EH] <br /> Subject: Final Temporary Piezometer Construction Details, PG&E McDonald Island <br /> Attachments: 485669323-PG&E McDonald Island 2007 Annual Report Figure 4-1.pdf <br /> Harlin, <br /> I understand that you wanted to receive a copy of the final design for the subject piezometers. I <br /> apologize for the delay in getting this to you,but MSE just submitted the 2007 Annual Report to <br /> RWQCB and this figure was final-drafted last week. <br /> FYI, the complex geochemical and statistical evaluations presented in the report concluded that Pond 3 <br /> soil and subsurface water(both shallow zone temporary piezometer groundwater and grab water <br /> samples from the intermediate/deep zone soil borings) do not indicate contamination from site COCs <br /> (barium, sulfate, sodium and chloride). In conjunction with the previous conclusion to which RWQCB <br /> concurred(that groundwater outside the Pond 3 footprint does not contain site COCs), PG&E is <br /> recommending corrective action termination and rescission of the WDR. <br /> If RWQCB concurs,monitoring wells,piezometers,well points and temporary piezometers will likely <br /> be decommissioned. We will contact SJCEHD again once we are ready to begin this process. In the <br /> interim, if you have any questions,please feel free to contact me. <br /> Regards, <br /> Robert A. Ellgas, Ph.D. <br /> Program Manager <br /> MSE Group <br /> 302 Pendleton Way <br /> Oakland, CA 94621 <br /> 510-383-9600 <br /> 510-383-9300 fax <br /> Robert Ellgas<rellgas@msegrp.conr> wrote on 12/14/07 @ 2:57pm: <br /> Harlin, <br /> As we discussed earlier today, attached is a markup of Figure 3-1, Temporary Piezometer <br /> Construction Details,with the change from a 2" borehole to a 5" borehole to satisfy the <br /> requirement of a 2" annular space around the piezometer casing. Also included is a previous <br /> change to clarify that a cement and 5%bentonite powder slurry is to be used to grout the <br /> piezometers to the surface. <br /> Precision Sampling has revised the drilling program based on the borehole diameter change and, <br /> as you know,they have scheduled a hollow stem auger rig to install the piezometers beginning <br /> on Monday, 12/17/07. The program is anticipated to be 2 1/2 days in duration. However, at <br /> McDonald Island, there is a chance of rain on Monday and rain is likely on Tuesday. We expect <br /> 3/18/2008 <br />