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rM <br /> C'LEARWWTER <br /> G a 0 U 1' <br /> -:---_-- Enaironmen taf Services <br /> determine the downgradient extent of contaminants. The hydropunch was performed in the <br /> former UST location to assess the vertical extent of hydrocarbons. Three soil borings were <br /> drilled to define the lateral extent of soil and groundwater contamination on the northeastern <br /> rP portion of the site and assess possible off-site sources. The results of this phase of investigation <br /> confirmed the verticle and horizontal extent of both sorbed- and disolved-phase contamination at <br /> the subject site. The results of this phase of investigation were submitted in Clearwater's <br /> Additional Assessment and Quarterly Groundwater Monitoring First Quarter 2000. <br /> Based on the significant sorbed- and dissolved-phase contaminant concentrations beneath the <br /> site, Clearwater recommended the testing of engineered in-situ remedial technologies at the site. <br /> g g g <br /> In order to effectively test these technologies, on February 22, 2002, Clearwater supervised the <br /> installation of one 4-inch dual-phase extraction well and one 2-inch airs sparge p P ge well at the core of <br /> the contaminant plume. <br /> On March 12, 13 and 14, 2002 Clearwater performed groundwater extraction (GWE) feasibility <br /> testing, combined GWE and soil vapor extraction (SVE) feasibility testing, and GWE/SVE with <br /> air sparge (AS) feasibility testing, respectively. Details on methods and results can be found in <br /> Clearwater's Well Installation and Feasibility Testing Report dated May 9, 2002. <br /> 2.3 Monitored Natural Attenuation Analyses <br /> As suggested in Clearwater's Corrective Action Plan and subsequently approved by the <br /> SJC/SJC/EHD, NINA testing was continued at the site for the fourth quarter 2003. The testing <br /> V= <br /> included field measurement of dissolved oxygen (DO), and the collection and submittal of <br /> additional groundwater samples to CytoCulture for bacterial enumeration, and inorganic <br /> chemical and nutrient assay. <br /> The purpose of MNA testing was to evaluate the occurrence and rates of intrinsic bioremediation <br /> i =1 of residual dissolved-phase hydrocarbons at the site. The work was incorporated with the regular <br /> scheduled quarterly groundwater monitoring for contaminant concentrations. <br /> ZB 178E iSOC System Installation/Start-up 4 Nov.24,2004 <br />