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• 0 Page 9 of 11 <br /> For your information, I have been in contact with Josh Ewert of GeoCon <br /> regarding which wells will be pressure grouted and which will have the <br /> contents removed. <br /> Including the requirement for monitoring wells #2, 3, & 11 as listed in <br /> the CVRWQCB August 17 letter, I have asked Josh to provide me a list of <br /> ALL of the wells for this site and a notation next to each as to the <br /> method of destruction he would like to use. I will review this proposal to <br /> see if the wells Josh has proposed for pressure grouting qualify. If they <br /> don't, they will be required to have the contents removed. To qualify for <br /> pressure grouting, the soil, gw, and vapor data indicating there is no <br /> residual contamination present must be available. Wells with NO data <br /> available will be considered UNKNOWN and not qualified for pressure grout. <br /> Typically, wells of unknown construction, obstructed, contaminated or in <br /> an area of known contamination*, or incapable of being properly pressure <br /> grouted must have the contents removed. The EHD is mandated by County <br /> Ordinance to require wells to have the contents removed (commonly noted by <br /> consultants and drillers as 'over-bored') if they do not meet the <br /> requirements for pressure grouting. <br /> *The EHD interprets 'area of contamination' as the current contamination, <br /> or lack of, in the well's most current lab data for all/any matrix. <br /> Laboratory concentrations for any constituent of concern that is <br /> significantly above acceptable detection limits indicates the well is <br /> contaminated and cannot qualify for pressure grout destruction. <br /> The EHD accepts wire line destruction (down-hole explosion) and over- <br /> boring of wells as 'removing the contents' . Wells much be drilled out <br /> with at least the same size auger as installed, or in the case of 'nested <br /> wells, with augers of adequate size to remove all the contents of the <br /> well. Experience has shown nested wells do not provide a casing that is <br /> centered in the borehole since a minimum of 2 inches of grout annulus is <br /> required between all casings and borehole at installation. As such, a <br /> nested well with two casings or even three casings that cannot qualify for <br /> pressure grout must have the destruction auger centered on the deepest <br /> casing and of adequate size to ensure the radius of the bit reaches across <br /> the borehole to completely remove the grout, bentonite seal, and filter <br /> pack that was installed during the well's construction. As an example, to <br /> destroy an original 10-inch borehole with two casings (one deep, one <br /> shallow), we have found that approximately a radius of 7 inches is needed <br /> to reach across to original borehole after being placed in the deeper <br /> casing which is offset approximately two inches from center. A 15 inch <br /> auger (with a 7.5 inch radius) is typically used since a 14 inch auger <br /> hasn't been found yet. <br /> Jim, I'll let you know the status of the well destruction method/plan <br /> after I receive and review the list. . <br /> Mike Infurna <br /> SJCEHD <br /> 209-468-3454 <br /> 11n12011 <br />