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a <br /> Frank Girardi [EH] <br /> y <br /> From: Mark.Wuttig@CH2M.com <br /> Sent: Monday, June 02, 2008 3:53 PM <br /> To: Frank Girardi [EH] <br /> Cc: Margaret Lagorio [EH]; OsbornS@kindermorgan.com; Kshelton@waterboards.ca.gov; <br /> roger.Iucich@ch2m.com <br /> Subject: RE: ADDENDUM -- Holt Well Destruction <br /> Frank, <br /> As we discussed, to clarify your questions below, the deeper wells as currently <br /> constructed and abandoned by pressure grouting will prevent cross contamination from the <br /> shallow to deeper groundwater zones, both now and in the future. The three wells (N-21, <br /> N-22, N-23) are completed in the clean deeper groundwater zone, below the 10 mg/L TPH-gas <br /> and 100 ug/L benzene contours shown in Figures 4 and 5 of the November 1, 2007 work plan, <br /> respectively. <br /> As noted in the work plan addendum, there is an annular cement grout seal both between the <br /> 15-inch borehole and the 8-5/8" conductor casing, and between the 8-5/8" conductor casing <br /> and 2" PVC casing. This concrete encases the 8-5/8" steel conductor casing below ground <br /> which will protect this casing against future deterioration. As described in the work <br /> plan, the surface of the casing will be removed to 3-feet below ground and topped with 1- <br /> foot foot of grout, which will encase the steel casing from above. The steel conductor <br /> casing will then be fully encased on cement grout. <br /> The annular space between the 2-inch PVC casing below the 8-5/8" conductor casing and <br /> above the screen is comprised of a bentonite pellet seal. This bentonite pellet seal will <br /> not be subject to future deterioration from hydrocarbon contamination because it is below <br /> the contaminated zone (i .e. , below the conductor, which was constructed to be below the <br /> hydrocarbon contaminated zone) . <br /> Pressure grouting the inside of the 2-inch PVC casing will fill the remaining voice space <br /> inside each of the 3 wells. The 10-foot long screen and filter pack at the bottom of the <br /> 2-inch PVC casing is short and located within a sandy interval at each location. <br /> Therefore, even though grout may not fully invade the filter pack outside of the screen, <br /> this is not necessary because the sandy interval outside of the screen and borehole is <br /> already permeable within the native formation itself. <br /> Please let me know if you need additional information. You can call me at 805-371-7817, <br /> ext. 23 . <br /> Thanks <br /> Mark <br /> -----Original Message----- <br /> From: Frank Girardi [EH] [mailto:fgirardi@sjcehd.com) <br /> Sent: Monday, June 02, 2008 2 :48 PM <br /> To: Wuttig, Mark/THO <br /> Cc: Margaret Lagorio [EH] <br /> Subject: RE: ADDENDUM -- Holt Well Destruction <br /> Mark, <br /> Thanks for the submittal of the WP. On page 2 of the WP, it is noted that the current <br /> construction (including annular seal) of these wells (N-21, N022, and N-23) is robust and <br /> protective of "groundwater conditions" . Can you elaborate as to what the "groundwater <br /> conditions" are and how the destruction of the wells by the pressure grouting method will <br /> not cause a cross contamination problem between shallow zone and deeper zone now or in the <br /> future? <br /> Frank Girardi, Senior REHS <br /> 600 E. Main Street <br /> Stockton, CA 95202 <br /> 1 <br />