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R <br /> Additional Groundwater Investigation and Remediation Feasibility Evaluation Work Plan <br /> Stockton Center Site Authority-University Park <br /> January 25,2005 <br /> Page 10 <br /> 6.0 REMEDIATION FEASIBILITY EVALUATION ' <br /> The proposed scope of this investigation includes a detailed examination of subsurface conditions through <br /> g <br /> detailed lithologic logging of soils, discrete-depth soil sample collection for analyses of chemical and <br /> physical properties, monitoring of chemical and physical parameters, and bench scale testing of site soil <br /> and groundwater. The bench scale testing is intended to evaluate the effectiveness of ozone injection, <br /> bioremediation, and/or other remediation technologies at the site. <br /> f <br /> Detailed geologic logging and analyses of physical properties of the soils is expected to yield important <br /> information about the complex site hydrogeology. It may potentially aid in recognition of preferred flow <br /> pathways (contaminant migration conduits) and in identification of potential means of remediation. <br /> Analyses of soil characteristics will include laboratory hydraulic conductivity tests {flexible wal(or tri- <br /> axial lab permeameter tests), bulk density/moisture content (to assist in effective porosity evaluation), <br /> total organic content(to evaluate oxygen demand of the soil) and particle size distribution and hydrometer <br /> rtests(to classify soils). <br /> _ Site management has requested the feasibility evaluation of less obtrusive, less aggressive, more cost' <br /> effective remediation alternatives. Chemical oxidation of the hydrocarbons into carbon dioxide and water <br /> by ozone injection is a potentially viable option for the site since it is anticipated to be effective on the <br /> site's most recalcitrant contaminant, 1,2-DCA. Residual oxygen from the 'reactions also encourages <br /> bioremediation in the outer reaches of the chemically oxidized zone (halo). Ozone injection is potentially <br /> ' attractive for the site because it may reduce contaminant concentrations in the vadose zone as well as,in <br /> the saturated zone. Subsurface hydrogeologic conditions beneath the site, however, may not be amenable <br /> L4'� to contaminant. remediation by ozone injection, and/or engineering may be necessary to increase the <br /> effectiveness of ozone injection. New ozone treatment techniques combining peroxide with the ozone, to <br /> r <br /> increase the effective radius of the application, are showing promise for vadose zone treatment. Ozone <br /> } 3 injection has also been documented to create nuisance conditions such as metals mobility in certain <br /> i <br /> environments,however. <br /> Enhanced natural attenuation through oxygen. infusion <br /> g yg (bioremediation).is also a potential Iow-cost, <br /> relatively unobtrusive, longer-term remediation option in which high levels of dissolved oxygen in <br /> groundwater .are achieved through mass transfer from a high surface-area interface (installed in <br /> monitoring wells). Insufficient subsurface data currently exists to effectively evaluate the progress of <br /> ' natural attenuation at the site, the potential for enhancement of the natural attenuation process through <br /> oxygen infusion, and/or the viability of active remediation alternatives such as ozone injection. <br /> l Investigation and monitoring of chemical and physical conditions and bench scale testing of site soil and <br /> groundwater are proposed to address these issues. Field parameters such as dissolved oxygen (DO), <br /> oxidation/reduction potential (ORP), pH, temperature, conductivity; and chemical parameters such as <br /> nitrogen, phosphate, total iron, ferrous iron, sulfate, alkalinity, biological oxygen- demand (BOD), <br /> chemical oxygen demand.(COD), total organic carbon, total inorganic carbon, and total dissolved solids <br /> (TDS) are some of the indirect indicators of natural attenuation and .the feasibility of ozone injection, <br /> oxygen infusion, etc. Bench scale testing is proposed to evaluate ozone injection and bioremediation <br /> (oxygen infusion, etc.) as feasible remediation methods of site soil and groundwater, to address potential <br /> concerns such as increasing the mobility of lead, arsenic, chromium and other metals in the site <br /> groundwater, and the potential consumption of ozone/oxygen by naturally occurring organic matter <br /> (thereby reducing .the effectiveness.of the treatment). Generally, the bench scale testing will provide <br /> insight into the subsurface conditions which will impact the remediation'processes, <br /> t ' <br /> CONDOR <br /> i <br />