Contaminated Sediment TMDLs: An Oxymoron?

摘要

Background/Objectives. Sediment contaminated with legacy pollutants such as pesticides,polychlorinated biphenyls (PCBs), and other chemicals banned from use years agorepresent a significant challenge to states’ total maximum daily load (TMDL) programs.These challenges manifest themselves in: (1) overlapping regulatory programs; (2) lackof existing point source discharges and site data; (3) atmospheric contaminant cycling;and (4) water quality standards established well below existing analytical capabilities.Approach/Activities. Many legacy pollutant sites are regulated under one or morefederal programs-including the Resource Conservation and Recovery Act (RCRA) andComprehensive Environmental Response, Compensation, and Liability Act (CERCLA)-that consider water quality standards as part of the process and as applicable or relevantand appropriate requirements. Consequently, legacy pollutant TMDLs oftenrepresent a form of regulatory double jeopardy. That is, successful execution of aCERCLA or RCRA cleanup does not preclude responsible parties from the TMDLprovisions of the Clean Water Act. Moreover, execution of legacy pollutant TMDLsoften invokes a double standard. Consider that the primary objective of the TMDLprogram is to restore our nation’s waters to their designated use (drinking water, recreation,support for aquatic life, or fishing). For legacy pollutants, this often translates intothe reduction of fish body burdens to levels acceptable for human consumption and theremoval of fish consumption advisories. However, once a legacy pollutant site makes itto a state’s 303(d) list based on consumption advisories, the TMDL process often involvesestablishing a water concentration target. In many instances, these concentrations,which are derived using bioaccumulation factors that relate human health risk-derivedfish body burdens with water column concentrations, are far below the analytical detectionlimit, exceed background pollutant concentrations, and are not supported by sitespecificdata.Results/Lessons Learned. One potential option is to apply to legacy pollutants thestrategy developed for mercury. That is, allow an “off ramp” in the form of a Category4(b) listing. This designation would require that controls implemented through existingregulatory programs (CERCLA, RCRA) are stringent enough to return the designateduses in a reasonable time period, as well as identify loading controls (e.g., best managementpractices, sediment remediation, and natural recovery). Moreover, establishingrecovery targets based on fish body burdens, rather than unmeasurable water qualitystandards, would simplify monitoring requirements and directly focus monitoring effortson the impaired use.