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Geosyntecc' <br /> consultants <br /> the Soil Closure Report by Geosyntec, 2013. The CVRWQCB concurred with the Soil <br /> Closure Report in an August 2, 2013 letter and began preparing the necessary <br /> documentation for closure of the soil source area. CVRWQCB has given verble <br /> concurracne for No Further Action with regards to Site soils and the No Further Action <br /> Required Concurrence if forthcoming. <br /> The AS system was installed as part of the Phase IV IRA in 2007 and includes a <br /> network of 59 sparging wells with 3- foot screened intervals positioned from 50- to 60- <br /> feet below grade, , immediately below the areas with relatively higher concentrations of <br /> VOCs in a saturated source area, as shown on Figure 3 (LFR, 2007). A mixture of <br /> ozone and air were supplied to each of the sparge wells using underground tubing from <br /> an air compressor and ozone generator located in the treatment system compound in the <br /> Southwestern portion of the Site. <br /> The AS system was shutdown July 2009 to monitor for re-bound of impacts in the <br /> saturated source area. Groundwater monitoring wells installed near the treatment area <br /> were sampled three times over a span of 9- months to monitor for rebound of VOCs <br /> associate with the saturated source area. The groundwater sampling events indicated <br /> that the AS system successfully reduced Site constituent concentrations within <br /> groundwater to below 100 ltg/1 with no significant rebound after the sparge system was <br /> shut down, (LFR,2009). <br /> System Decommissioning and Well Destruction Work Plan 4 07/18/2014 <br />