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• Reduction in residual risks from remaining wastes <br /> • Short-term risks during implementation,including threats associated with excavation, <br /> transportation,and redisposal <br /> • Potential for exposure to remaining wastes considering excavation,transportation, <br /> redisposal,and containment <br /> In this category,the"no action"alternative would have normally been ranked as low because it <br /> will neither prevent additional infiltration and subsequent generation of leachate, nor prevent <br /> further migration of leachate to groundwater. However, since the nature and extent of the <br /> VOC release is significantly low the"no action"alternative has been ranked as medium at this <br /> time. In addition there are minimal short-term exposure risks since no activities would be <br /> conducted which would result in exposure to the leachate or leachate-impacted groundwater. <br /> Source control has been ranked as being of high effectiveness because, while it will not <br /> prevent migration of leachate-impacted groundwater, it will reduce the generation and <br /> migration of additional leachate. Reducing the generation of additional leachate <br /> subsequently reduces the residual risks associated with the leachate. The short-term risks <br /> associated with implementing source control are minimal because the refuse, leachate, and <br /> leachate-impacted groundwater are not exposed during implementation activities. Finally, <br /> the potential for future exposure to remaining wastes is reduced since the generation and <br /> migration of future leachate is reduced or eliminated. <br /> The two remaining alternatives, groundwater extraction and treatment and, physical <br /> barriers would have normally been ranked as highly effective when combined with source <br /> control, since generation of additional leachate is reduced (resulting in a reduction in <br /> residual risks), and either the migration of leachate or leachate-impacted groundwater is <br /> reduced, or the leachate-impacted groundwater is treated. However, since the nature and <br /> extent of the VOC release has been limited, it is probably not practical at this time to <br /> implement these alternatives. Therefore these alternatives were ranked medium. In <br /> addition the short-term risks associated with implementing these alternatives are higher <br /> than the "no action" or source control alternatives since these alternatives involve <br /> exposure to the leachate-impacted groundwater (during either well installation or slurry <br /> trench excavation). <br /> 4.2.3 Permanence <br /> The permanence of an alternative refers to whether it provides a permanent solution. For <br /> example, the permanence is dependent on whether the COCs are destroyed or whether the <br /> solution is merely temporary. This category also addresses the long-term management of <br /> the project including monitoring and operation and maintenance(O&M)requirements. <br /> SAC\N�PJOM3M390031.9BG-94\sd8:1 Rev.0 420/95 <br /> 0939.003.19 4-6 <br />