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Nestle USA, Inc.—Ripon, CA January 28, 2011 <br /> 2011 Revised Feasibility Study <br /> decreased, surrounding impacted saturated soils release concentrations to <br /> groundwater). <br /> Implementability of this alternative is low, with problems occurring primarily with <br /> treated water disposal and well efficiency degradation. Also, finding suitable <br /> locations for extraction wells and treatments systems is expected to be <br /> problematic. Initial construction costs are high for this alternative, as well as <br /> O&M cost. Given the length of time to achieve ARAR compliance, this <br /> alternative is very costly (see Appendix D). <br /> 10.1.3 Alternative 3 <br /> Alternative 3 involves the implementation of pump-and-treat technology and in- <br /> situ chemical treatment in highest concentration source and plume areas (see <br /> Figure 9). <br /> 10.1.3.1 Description <br /> In this alternative, pump-and-treat technology is expanded to include five <br /> extraction wells in the Upper and Intermediate Aquifers for plume containment. <br /> Current pump-and-treat systems and operational rates remain constant in the <br /> Upper and Intermediate Aquifers. In both the Upper and Intermediate Aquifers, <br /> in-situ chemical treatment is implemented for areas known to have the most <br /> elevated TCE concentrations in soil and groundwater. Depending upon the <br /> process method chosen for in-situ treatment, hazardous materials may be used. <br /> All aquifers are monitored for intrinsic remediation. Institutional controls are <br /> implemented for all aquifers, including the proper abandonment of vertical <br /> conduits, particularly wells no longer operating and on the NPC properties. In <br /> addition, several municipal and private wells are no longer active as part of the <br /> institutional controls proposed. Figure 9 provides an overview of the main <br /> remedial components of Alternative 3. <br /> 10.1.3.2 Assessment <br /> Alternative 3 provides human health and environmental protection by decreasing <br /> COC concentrations below ARAR goals for soil and groundwater in 12 to 15 <br /> years and by containing the plume. This alternative also minimizes further COC <br /> impact to municipal and private wells. Likewise, RAOs are met within the <br /> approximate 12 to 15 year time frame, based on the numerical modeling <br /> performed to assess this scenario. <br /> Long-term effectiveness depends upon the efficiency of extraction wells and <br /> treatment systems, although not as significantly as in Alternative 2. Decreasing <br /> well efficiencies cause the length of time to complete this alternative to be <br /> extended. Once ARARs are met, remaining risk will be low. Long-term <br /> commitment to O&M and to the monitoring of treatment systems is extensive. <br /> O&M for extraction wells is anticipated to be considerable and may include <br /> replacing wells when well efficiency diminishes due to several reasons such a <br /> foiling, calcification, etc. Long-term effectiveness of in-situ chemical treatment is <br /> more efficient with fewer complications. <br /> 42 <br />