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Musco Family Olive Company - 2 - 21 March 2007 <br /> y <br /> • Following installation of the Phase I wells, Musco must perform monthly monitoring and <br /> sampling of off-site groundwater monitoring wells A(R2)/ B(R3) for iron, manganese, <br /> and the parameters and constituents listed in the Site Specific Groundwater Monitoring <br /> section of Monitoring and Reporting Program No. R5-2002-0148. Monthly sampling <br /> shall begin immediately upon installation of the wells and shall continue through <br /> November 2007, to expedite the collection of the minimum samples required for <br /> developing background groundwater concentrations. <br /> • In accordance with MRP No. R5-2005-0024, section D., the minimum number of <br /> groundwater samples required to develop background groundwater concentrations is <br /> eight samples. The Discharger shall make every effort to collect the minimum eight <br /> groundwater samples from wells A(R2)/B(R3) through November 2007. By 1 <br /> December 2007, the Discharger shall submit a proposed Water Quality Protection <br /> Standard report that includes a list of constituents of concern (CDCs), proposed <br /> concentration limits, and the point of compliance and all monitoring points. <br /> • Beginning in January, the Discharger may revert to quarterly monitoring and sampling <br /> in accordance with the Site Specific Groundwater Monitoring section of MRP No. R5 <br /> 2002-0148 and the Groundwater monitoring section of MRP No.R5-2005-0024. <br /> • Musco has proposed to install three additional wells south, southwest, and southeast of <br /> Field 95. According to the work plan, the three wells are being installed to characterize <br /> upgradient water quality. Staff has previously cautioned Musco concerning these well <br /> locations. The wells have been proposed offsite in the upland area where a higher <br /> potential to drill into the Neroly Formation is possible. According to the Background <br /> Groundwater Quality Report dated 30 July 2004 and prepared by Kennedy/Jenks <br /> Consultants, "Dibblee also identified the Neroly Formation (Tn) underlying the Tps unit <br /> in the western part of the site, just east of the mapped trace of the Midway Fault a <br /> distinguishing lineament trending northwest and bisecting the site (Kleinfelder, 2004b)." <br /> Staff is concerned the proposed borings in this area will monitor bedrock conditions <br /> and not the unconsolidated alluvium where current groundwater impacts have been <br /> observed. Staff requests that Musco submit an explanation discussing the rationale for <br /> these well locations and identify the geologic horizon(s) the wells are intended to <br /> monitor by 10 April 2007. <br /> • Staff recommends that proposed well C(R3) southwest of MW-1 be moved easterly in <br /> a direct line south of well MW-1. This location should be no more than 100 feet from <br /> Field 95 property boundary. <br /> • Staff has not received a formal report concerning water samples collected from Borings <br /> B-1 through B-3, which were advanced in November and December of 2006. Based <br /> on the preliminary data presented in the 12 January 2007 meeting, it appears TDS <br /> values in these borings ranged between 4,050 mg/L in boring B-1 and 910 mg/L in <br /> boring B-3. It is evident from these groundwater samples that TDS values decrease <br /> west of the Midway Fault and that groundwater collected from boreholes associated <br /> with bedrock conditions (boring B-1) contain higher TDS values than groundwater <br /> associated with unconsolidated alluvium conditions (borings B-2 and B-3). <br />