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• October 20711 based on the attenuation factor calculated for MW-3(40004) <br /> • May 2094: based on the attenuation factor calculated for MW-3 with a 30% factor of safety. <br /> GZA agrees with the calculation that the core of the groundwater plume(MW-3 &MW-5) will reach <br /> MCLS for benzene (<I ug/L) between May 2036 (4001) and October 2071 (40004), depending on <br /> the attenuation factor used. It is expected that the groundwater plume will collapse in on itself with <br /> edges of the contaminant plume (MW-1, MW-6, MW-8 & MW-108) degrading at a faster rate than <br /> the core. <br /> Well Destruction Procedures <br /> We concur with the wel I abandonment procedure for MW-201 as stated in the SJCEHD letter dated <br /> May 21,2013. <br /> • Drill out the well to TD(155 ft bgs) <br /> • Leave steel conductor casing in place down to 46 ft bgs <br /> • Grout the borehole from the base up using.a tremie pipe.The borehole wil I be grouted from <br /> its base to the ground surface. <br /> We concur with the well abandonment.procedure for the three(3) CMT wells as stated in the <br /> SJCEHD letter dated May 21, 2013. <br /> • Use 100 grain prima'cord,place to the full depth of the CMT well in the center channel. If the <br /> center channel-is plugged,the SJCEHD will be informed immediately. <br /> • Grout well channels(if preferred by blasting contractor) <br /> • Detonate explosive <br /> • Drill out the entire contents of the well using stinger and auger equipment <br /> • Grout the borehole from the base up using a tremie pipe.The borehole will be grouted from <br /> its base to the ground surface. <br /> Please contact me at (209) 522-4119 should you have any questions or need more <br /> information. <br /> Thank you, <br /> ! �nNAL G� , <br /> ^ 1 r Digitally signed by Raynold 40 <br /> K Kabl- �{ <br /> �laynold Kabl w, <br /> ou, e ogical Ted <br /> IRA1iN0lD 1_ <br /> ien • .r KARLANO <br /> --- Dat:20i3.06:81 0853-0T00'' iii ° ¢+ - <br /> 1No.523A <br /> � <br /> s <br /> Raynold 1. Kablanow II, PhD <br /> PG, CHG <br /> CC: Steve Valentine <br /> Jim Barton, RWQCB - CV <br />