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'I <br />� n <br /> - Addendum to Interim Corrective Action Plan <br /> Frontier Transportation, Inc. <br /> April 14, 2006 <br /> Page 8 <br /> 9 a <br /> k = �Ha — H1 ) ]n R Rr <br /> This measurement also requires the pumping rate to be a value that keeps the <br /> water level the same over time in the pumping well. <br /> Dewatering in the pumping wells will be plotted logarithmically to identify <br /> aquifer and well loss. Aquifer dewatering will be observed in the MW-8 (near the wells <br /> with product and the source area) and MW-9 (down gradient sentinel) observation <br /> monitoring wells and in additional to identify the relationship between dewatering and <br /> time (t), distance (r), transmissivity (T), Specific Yield (S) and lateral conductivity (K) <br /> under conditions of constant discharge. The general pattern is that the smaller the T and <br /> S values, the larger the drawdown values near to the point of discharge and the larger <br /> the volume of aquifer affecter through time. Extension of the cone of depression to <br /> each of the observation monitoring wells will determine the lateral extent of aquifer <br /> dewatering caused by discharge of sufficient water, where possible, from the two <br /> pumping wells. <br /> Based on field data collected from a groundwater pump test, BEA will determine <br /> groundwater velocity and a pump rate radius of influence. Velocity will be determined <br /> to identify and model contaminant migration and potential for technically and cost <br /> effective groundwater pumping and treatment. The work plan for the groundwater <br /> extraction (pumping and treating) will be completed based upon the results from the <br /> aquifer testing. <br /> While onsite for aquifer testing passive skimmers will be deployed in those wells <br /> where free product has been identified, MW-2 and MW-21 . The passive skimmers will <br /> have a capacity of at least 0. 10 gallons of free product. Initially, the free product will be <br /> removed from the skimmers at least once per week up to five times per week, depending <br /> upon the recharge rate. Emptying of the passive skimmers will be adjusted as the <br /> recharge rates change. <br /> INSTALLATION OF ADDITIONAL WELLS FOR AQUIFER TESTING <br /> In order to perform the aquifer tests there must be three wells within a close <br /> range. To meet this specification, two new monitoring wells will be advanced near each <br /> of the test locations, MW-8 and MW-9. See Figure 2 for proposed locations at 10' and <br /> 20 ' distance from these locations. <br /> A hollow stem auger drill rig will be used to provide the soil borings for well <br /> installation. Drillers will hold a California State C-57 contractor's license. Typical auger <br /> size for the well installation described below is 8-inch outside diameter and 64nch inside <br /> diameter. The borings for shallow well installation will be advanced to 20 ' bgs. <br /> i li 8 <br />