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implementability is another factor in the remedy selection process that needs to be completed <br /> as part of the FS, so it is evaluated herein. With this in mind, an implementability analysis is <br /> presented below. <br /> Several challenges related to implementing an IAS system of this size were identified. <br /> Implementation challenges include: <br /> • The length of the barrier would be almost one mile (4,500 feet; 0.85 mile). A system of <br /> this size would require access to a number of properties. Access agreements would <br /> need to be executed that allowed for the construction of monitoring wells, above <br /> ground infrastructure (fencing, sheds to house air compressors and other equipment), <br /> and subsurface trenching for system piping. <br /> • Long term access to private properties would be required for operation and <br /> maintenance. <br /> • The length of the system would require a modular type design where separate IAS <br /> compounds housing compressors, supervisory control and data acquisition (SCADA), <br /> manifold piping/valves, and other system components were constructed at various <br /> stations along the biobarrier alignment. The entire biobarrier alignment would likely <br /> have to be secured by fencing. The final as-built system would consist of an almost <br /> mile long fenced area adjacent to the Stanislaus River which may detract from the <br /> recreational use of the river and interfere with wildlife using the river. <br /> To summarize, there are substantial logistical and engineering challenges along with some <br /> environmental impact to overcome for implementing biosparging in the WWTP area. <br /> Overcoming these challenges would greatly increase the cost and may be some <br /> environmental concern for implementation. <br /> 3.4 COST <br /> In Section 3.2, it is shown that biosparging would be ineffective for treatment of all COCs in <br /> groundwater within the targeted treatment area because TCE does not degrade under aerobic <br /> conditions. Therefore, biosparging should not be implemented on this basis alone. The <br /> implementability analysis presents substantial logistical and engineering challenges that would <br /> preclude the implementation of biosparging. However, cost is another factor in the remedy <br /> selection process that needs to be completed as part of the FS, therefore, cost of the remedy <br /> in question is discussed below. <br /> A feasibility level cost estimate has been developed for a biobarrier adjacent to the Stanislaus <br /> River (Table B.1-1) even though from a technical perspective, the biosparging approach is <br /> AMEC Geomatrix, Inc. <br /> \\oad-fs1\doc_safe\9000s\9837.006\4000 REGULATORYTS Assessment_Apx B_012711\Attachment B.1\Attach B1.doc 131-7 <br />