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Page 14 of 15 <br /> the requirements for pressure grouting. <br /> *The EHD interprets 'area of contamination' as the current <br /> contamination, or lack of, in the well's most current lab data <br /> for all/any matrix. Laboratory concentrations for any <br /> constituent of concern that is significantly above acceptable <br /> detection limits indicates the well is contaminated and cannot <br /> qualify for pressure grout destruction. <br /> The EHD accepts wire line destruction (down-hole explosion) and <br /> over-boring of wells as 'removing the contents' . Wells much <br /> be drilled out with at least the same size auger as installed, <br /> or in the case of 'nested wells, with augers of adequate size <br /> to remove all the contents of the well. Experience has shown <br /> nested wells do not provide a casing that is centered in the <br /> borehole since a minimum of 2 inches of grout annulus is <br /> required between all casings and borehole at installation. As <br /> such, a nested well with two casings or even three casings that <br /> cannot qualify for pressure grout must have the destruction <br /> auger centered on the deepest casing and of adequate size to <br /> ensure the radius of the bit reaches across the borehole to <br /> completely remove the grout, bentonite seal, and filter pack <br /> that was installed during the well's construction. As an <br /> example, to destroy an original 10-inch borehole with two <br /> casings (one deep, one shallow), we have found that <br /> approximately a radius of 7 inches is needed to reach across to <br /> original borehole after being placed in the deeper casing which <br /> is offset approximately two inches from center. A 15 inch <br /> auger (with a 7.5 inch radius) is typically used since a 14 <br /> inch auger hasn't been found yet. <br /> Jim, I'll let you know the status of the well destruction <br /> method/plan after I receive and review the list. . <br /> Mike Infurna <br /> SJCEHD <br /> 209-468-3454 <br /> -----Original Message----- <br /> From: Jim Barton fmailto:jbarton@waterboards.ca.eovl <br /> Sent: Wednesday, August 17, 2011 7:32 AM <br /> To: Stephanie McKenna <br /> Cc: Brenda Evans <br /> Subject: Re: 5400 Pacific Avenue Stockton <br /> Hi Stephanie and Brenda, <br /> attached is a PDF copy of my well abandonment approval letter <br /> that is being mailed today. Thanks. <br /> Jim Barton <br /> James L.L. Barton, P.G. <br /> Engineering Geologist <br /> 12/20/2011 <br />