Stormwater discharge testing will be set by the DEC under the County's general stormwater discharge permit. Marsh sediments will be tested for arsenic, cadmium, copper, lead, mercury, and silver at a minimum. Leachate will be tested monthly for the first several years for biological oxygen demand (BOD), total suspended solids, total organics, and various metals including antimony, cadmium, chromium, copper, lead, mercury, nickel, silver and zinc at a minimum. The above parameters will be included in the long-term monitoring plan, however, the review of the County's plan by DEC and DOH may result in the addition of other parameters. Subsequent to the first five (5) years of monitoring the parameter list may be reduced based on trends in the data. Issue 14: Since the long-term effectiveness of the proposed remedy is based on the long-term ability of the cap to minimize the infiltration of water into the landfilled waste, what measures will be taken to insure the cap's integrity in the long-term? How will typical causes frr cap failures such as freezing and thawing of the - , hner, burrowing animals, impact of heavy equipment during installation, and pinholes during manufacture and construction, be addressed? Why not use a composite cap such as 3-feet of clay between two layers of 100 millimeter very low density polyethylene VLDPE? Even if the cap is 100 percent effective in perpetuity, tidal influences from the Hudson River will continuously draw contaminants from the site. This lateral flow should be monitored and reduced if possible. .. ResDonse: The cap for the CPL has been specifically designed to resist stresses induced by frost heave, differential settlement, and temperature changes. During installation, the liner will be protected by a cushion layer below and at least one foot of soil will be placed on the liner before heavy equipment is brought above it. The gravel (rock) drainage layer above the liner should protect it from burrowing animals. Close quality control must be performed by the contractor with strict quality assurance conducted by the County's engineer in order to meet the DEC approved plans and specifications. DEC also proviaes weekly oversight of the construction activities. While all of these measures should insure that a sound cap is constructed, the critical part of any cap's function is long-term maintenance. As one commenter noted, **theprice of freedom is eternal vigilance and we must be ever'vigilante of this remedy.'* DEC requires an operation and maintenance plan for this site which will include environmental monitoring and inspections of the cap for erosion, cracking, differential settlement, etc. However, since this site will become an extension of the Croton Point Park and a future habitat for birds and other wildlife, the DEC anticipates a significant number of public observers will also be winspectors**of this cap in the future. DEC encourages the general public to contact the County and the State if they detect any signs of failure of the cap. The DEC believes the cap designed for the CPL will perform as well as a composite cap based on the approved cap design, the estimated infiltration rate, and continued long-term maintenance. It is estimated that 99.9 percent of the current infiltration of water into the landfill will be eliminated by the cap design proposed for the CPL (see FS Appendix A) which is comparable to a composite cap. This reduction in infiltration is based on proper installation and maintenance of the cap. Procedures are in place to provide for proper installation of the cap as described above. As mentioned above, the long-term maintenance of the cap is expected to be very good due to the future use of the site as a park. Long-term monitoring of groundwater will assess whether significant lateral migration of contaminants persists due to tidal influences. Issue 15: To prevent surface erosion and damage caused by plant roots it is recommended that a drought resistant species such as white clover and'weeping lovegrass be planted on the cap's topsoil layer. It is recommended that a natural meadow with shrub thickets on the edges . be established on the final cover topsoil to provide critical sustenance for large numbers of breeding, migratory, and wintering species. There are numerous plants and shrubs that have shallow root systems that will not impact the liners. Resoonse: Both white clover and weeping lovegrass have already been included in the final cover planting specifications. The second recommendation is excellent and is being carefully reviewed by DECts biologists and engineers with the goal of providing suitable habitat for breeding, migratory, and wintering species of birds and other wildlife while not compromising the cap's integrity. . - .DEC may also solicit additional input from the public before finalizing the selection and locations of plants and shrubs. Issue 16: The marsh is being overtaken by large stands of common reed which