EPA softens stand on controversial contaminated sediment standards In a major policy shift on sediment contamination in fresh and marine waters, EPA has acknowledged that current scientific understanding does not support the setting of enforceable numerical standards for sediment cleanups. Instead, the agency intends to publish sediment quality criteria (SQC), specifying levels under which ecological or human health would not be harmed, as guidelines or recommendations, according to Office of Water officials. There are too many site-specific variations in sediment composition that affect the bioavailability of contaminants in sediment to justify a nationwide set of standards, said Betsey Southerland who is spearheading development of EPA's contaminated sediment strategy. Since 1990, EPA has been developing SQC as part of its strategy to remediate contaminated sediments and to guard against future contamination. Central to this strategy, which was published on May 6 (see sidebar), are equations that regulators use to determine whether the contaminant levels in the sediments are above or below the numerical standards that represent an unacceptable risk
to environmental or human health. Once finalized, these numerical standards will be incorporated into an array of EPA programs, according to the strategy. For example, they will be used when developing permits for industrial discharges, harbor dredging, and ocean dumping. They also will be referred to when developing cleanup levels at Superfund sites with contaminated sediments.
Once finalized, these numerical standards will be incorporated into an array of EPA programs. EPA's approach to the sediment quality criteria is based on the theory of equilibrium partitioning, which assumes that the bulk sediment concentrations of chemicals, organic carbon, and the interstitial water trapped in the sediment are in equilibrium. On the basis of assumptions about each chemical's affinity for water, the SQC are calculated so that the interstitial water meets
The Contaminated Sediment Management Strategy In its Contaminated Sediment Management Strategy, published May 6 (Federal Register, 1998, 63 (87), 25,037-25,040), the agency sets out plans for regulatory actions to control and reduce the problem. EPA studied sediment quality data from 1372 watersheds out of the more than 2000 in the continental United States and found that 96 contain "areas of probable concern" where potential adverse effects of sediment contamination are more likely to be found. Most of the problems come from past pollution by persistent chemicals. Actions listed in the strategy include • Use sediment quality criteria and standard sediment testing methods to evaluate contamination. • Propose that acute sediment toxicity tests be added to pesticide regulation. • Incorporate measures to protect sediments from contamination in discharge permitting programs for stationary sources. • Issue new and revised effluent guidelines for industrial discharges to protect sediments. Copies of EPA's Contaminated Sediment Management Strategy (EPA723-R98-001) are available on the Web at http://www.epa.gov/0ST/. —R.R.
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water quality criteria established in Clean Water Act regulations. But there is considerable scientific debate over many of the assumptions involved in this theory. Contentious issues include whether the theory adequately represents the feeding habits of sediment-dwelling organisms and whether water quality criteria, based on data for animals living in the water column, are appropriate for animals that live in sediment. Using equilibrium partitioning, EPA has developed, but not proposed, some 30 SQC for organic compounds and expects to have criteria for metals ready in another year, according to Southerland. But the proposal has been stalled by debate over whether the SQC should serve as strict pass-fail standards with the force of law or as screening tools to identify potential problems. In the past, EPA has held firm to the view that SQC should be introduced with the force of law. For 10 years the U.S. Army Corps of Engineers has effectively opposed publication of SQC, claiming that the state of the science is insufficient to justify passfail standards. The Corps' interest stems from its shared responsibility with EPA for assessing the environmental impact of navigational dredging. The Corps has blocked publication of SQC by predicting that adopting enforceable criteria would slow down dredging and have severe economic consequences on major U.S. ports. Most interested parties—state regulators, other federal agencies, environmental groups, and the shipping industry agree that guidelines are a good first step. Despite this apparent breakthrough, implementation of sediment quality guidelines remains in disarray. Negotiations between Corps and EPA officials broke down following publication of EPA's Contaminated Sediment Management Strategy because the Corps asserted that the document calls for SQC to be used as strict pass-fail numbers. "The EPA people lied to us" about the SQC, said Joe Wilson, who heads the Corps ocean dredging and permitting branch. —REBECCA RENNER
