PERFORMANCE-BASED SYSTEM FOR POST-CLOSURE CARE AT MSW LANDFILLS

摘要

The objective of this paper is to present a performancebasedrnsystem for evaluating post-closure care (PCC) atrnMSW landfills. This new approach addresses long-termrnstewardship of landfills by assessing current and futurernimpacts to the environment, and was developed to berncompletely consistent with the intent of applicablernFederal, state, and local regulations and guidance (i.e.,rnusing risk-based evaluations in a modular,rnstraightforward method to produce a performance-basedrnapproach to protecting the environment). The four mainrnaspects of landfill post-closure monitoring andrnmaintenance required under RCRA Subtitle D (i.e.,rnoperation of leachate collection system, gasrnmanagement, groundwater monitoring and protection,rnand cap maintenance) are considered. The approachrnuses logic diagrams within which each aspect of PCC isrnevaluated sequentially by means of a user-friendlyrnmodular system. Each of the four aspects of PCC arernassigned a unique ‘module’, with evaluations generallyrnperformed within ‘sub-modules’.rnThe approach presented in this paper represents a morernrealistic and environmentally protective strategy for thernmanagement of closed landfills than the current timebasedrnapproach under Subtitle D. The approach enablesrnthe owner/operator to identify those operationalrnpractices that can best mitigate environmental risk and,rnwhere practicable, implement certain practices at closedrnsites to help reduce long-term risks to the environment.rnA goal of this program is to encourage thernowner/operator to focus landfill design and operation onrnreducing post-closure impacts by emphasizing therninterrelation between these three periods (i.e., design,rnoperation, and post-closure) of the life-cycle of arnlandfill.rnThe authors believe that the proposed approach willrnresult in increased protection of human health and thernenvironment because assessments of environmentalrnimpact and potential risk posed by the source will bernrequired before any aspect of PCC may be reduced orrndiscontinued. This approach is currently being refined,rna process which involves on-going discussion withrnindustry, regulators, and stakeholders as well asrndemonstration of its appropriateness through sitespecificrncase studies. As such, this paper represents anrninterim step in the process of developing guidance forrnperformance-based evaluation of PCC.