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OUR <br /> the north end and one injection well on the south end on a quarterly basis for multiple lines of <br /> ERD evidence. This extra monitoring will provide better evaluation of the consistency of ERD <br /> occurrence throughout the injection barrier, and a better assessment of the ability of the barrier to <br /> intercept up gradient contaminants and deliver substrate to down gradient contaminants. <br /> Response 1: <br /> LFR agrees that there will be a benefit to monitoring the north and south edges of the injection <br /> barrier for multiple lines of ERD evidence. In fact, the monitoring program outlined in the Phase V <br /> IRA Detailed Plan ("the current monitoring program") includes quarterly monitoring of the 22 <br /> enhanced reductive dechlorination (ERD) injection wells for organic substrate indicators (i.e., <br /> TOC or visual presence of substrate) and field biochemical parameters (i.e., DO, ORP, pH, and <br /> conductivity); however, laboratory analysis for volatile organic compounds (VOCs) and other <br /> redox indicators are not part of the current monitoring program. Data collected during the most <br /> recent quarterly monitoring event conducted in April 2008 showed that substrate is still visibly <br /> present in the wells (see photograph below). As discussed during the June 16, 2008 conference <br /> call, further laboratory analysis for multiple lines of ERD evidence will not be performed if <br /> substrate is visibly present in the wells because the substrate will likely interfere with the <br /> laboratory analyses and because the presence of substrate indicates that ERD is likely taking place <br /> in the well. Further laboratory analyses described below will start after substrate is no longer <br /> visibly present in the injection well. <br /> Photograph showing substrate in bailer. <br /> Iv-Response to RWQCB-Lincoln-Ju108.06750.doc:LMT 2 <br />