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Data on Superfund Sediment Sites
60 Tier 1 Sediment Sites - EPA tracks the cleanup progress at all Tier 1 sediment sites. Tier 1 sites are sites where:
- Remedy has been selected, and
- EPA signs or concurs on the decision document, and
- Remedy includes dredging or excavation of at least 10,000 yd3, or
- Remedy includes capping or MNR or at least 5 acres.
As of September, 2005, there are 60 Tier 1 sediment sites. Because many of these sites are large, many have selected a different remedial component for separate areas of the site. EPA is gathering and evaluating information on 98 areas within these 60 sites.
Preliminary Data on 60 sites/98 Areas
- A little over 1/2 of the areas are rivers and streams and about 1/3 are wetlands.
- PCBs were the primary contaminants of concern driving risk at 1/2 the areas, while metals drove the risk at 1/3, and PAHs drove the risk at 1/5 of the areas.
- Ecological risk drove the need for cleanup at about 1/5 of the areas and drove part of the need for cleanup at 3/4 of all areas.
- At the 60 sites, sediment dredging or excavation was the sole remedy at about half the sites, while 1/3 included capping and/or MNR in addition to dredging or excavation. Capping or MNR alone were selected at less than 10% of the sites, but MNR is frequently a component of remedies.
- The volume of sediment removed was less than 50,000 yd3 at 1/2 of the areas, while the volume exceeded 1 million yd3 at 10%.
- The number of areas dredged vs. excavated were about the same, and at almost 1/2 of these areas, a thin layer of sand was used to backfill the area.
- Caps range in size from less than 1 acre to 430 acres, but most are between 10 and 70 acres.