disposal 04 the sediments is from $2,650,000 (15,000 cubic yards) to $4,435,000 (45,000 cbbic yards). If these materials are disposed of offsite the coets will increase to an estimated total of between $4,150,000 (15,000 yde) and $8,935,000 (45,000 yds). Implementation of this alternative worlld result in a significant short term disturbance of this sensitive habitat. Time to 1mplement:b months Direct Capital CosU: $2,650,000 to $8,935,000 Estimated Annual Costa: None-Monitoring costs are included in Alt.#l Alternative 48: Earntern narsh channel Monitoring This alternative consists of the elements of Alternative 1: no action that involve monitoring and sampling of the Croton Marsh area. No active remedial efforts are included under this alternative for the eastern channel area. Current studies have shown that the continued decline in biomass predicted by previous studies has not occurred. This is primarily due to the invasion of this area by phragmites which is a highly productive plant species. The marsh is valuable habitat for bird and reptile species that are of special concern and contains plants that are on the New York State Watch List. Based on the sediment sampling results under this monitoring akernative, if significantly higher concentrations of contaminants are found the impacts will be reevaluated. Time to Implement: None 8. Direct Capital Costs: Nolle Estimated Annual Costs: Nohe (Monitoring coats included in Alt.#l) EVALUATION OF ALTERNATIVES During the detailed evaluation of alternatives, each altbrnative is asseseed against the seven evaluation factors which were presbnted in Section V of this ROD, Since alternatives 4A and 4B deal exckusively with the Eastern Marsh Channel, they will be compared to each other in conjunction with the proposed source control alternative. 1. Source Control Alternatives 'Alternative 1 would not be protective of human health and the environment due t o the long-term risks identified in the risk assessment and briefly summarized in Section 1II.C of this ROD. Alternatives 2 and 28 would have equal overall protectiveness since they both isolate and contain the waate in the long-term. Alternative 3 would be the most protective of this local area as it would totally remove the waste and relocate it to several permitted land disposal facilities. Alternatives 2, 2B and 3 would substantially comply with ARARs while Alternative 1 would not. Part 360 would be complied with for all alternatives except Alternative 1. Groundwater and surface water standards/background quality would eventually be achieved by all alternatives except Alternative 1 by eliminating or isolating the waate mass as the source of contamination and allowing natural attenuation to occur. The amount of time to achieve water standards/background quality will vary with Alternatives 2, 28 or 3 but is estimated to take 15, 8, or 6 years respectively baaed on the groundwater model. In the eight (8) years it would take Alternative 2B to achieve water standards/backgrouqd quality, Alternative 2 will have reduced the contaminant loading by over 9 0 percent. Accelerating the capping schedule by two years by proceeding with the design of the cap prior t o this ROD has resulted in a greater reduction in contaminant loading to the Hudson River than would result from 15 years of actively pumping the leachate under Alternative 2B. e t e r n a t i v e 3 has the greatest long-term effectiveness followed by Alternatives 2B and 2 (equal values), then alternative 1. None of the remedies is considered permanent or results in a reduction of 'toxicity or 'volume in that the hazardous waste would not be treated. This is due to the heterogenous nature and the size of the CPSL which make it impassible t o locate the hazardous waste. The mobility of the waate is reduped by Alternative 3 the most, followed by Alternatives 2B, 2 and 1 in that order. Alternative 2 has the greatest short-term effectiveness in that it has a relatively short time to implement with a significant rapid reduction in mobility and therefore, excellent short-term effectiveness. Allternative 1 can be implemented the fastest but has no reduction in mobility and therefore is not effective in the short-term. Alternative 28 would take longer to implement than Alternative 2 and would have similar short-term benefits. Alternative 3 would take much longer to implement than Alternatives 1, 2 or 2B and also has the greatest potential for ehort-term exposures due to dust and volitilization of organics during excalration of the waste. Alternative 1 is the easiest to implement and the lowest in cost since no action would be taken. Alternative 2 is the easiest "action alternative" to implement and least cost followed by Alternatives 2B and 3 regpectively. 2. C m t o n Narsh Eastern chainel ~edireitAlternative. Alternative 4A is more protective than Alternative 4B in the long-term due to the removal of sediments which have elevated metal concent/rations. However, the remova.1 of sediments in Alternative 4A