IMPLEMENTATION AND MONITORING OF A COMBINED SEDIMENT CAPPING AND HABITAT RESTORATION PROJECT AT A MERCURY CONTAMINATED MARINE SEDIMENT SITE

摘要

The Whatcom Waterway Site,located within inner Bellingham Bay, Washington consists of intertidal and subtidal aquatic lands within and adjacent to the Whatcom Waterway in Bellingham,Washington.Georgia-Pacific completed a Remedial Investigation/Feasibility Study(RI/FS)of the Whatcom Waterway Site in July 2000 under Washington State’s Model Toxics Control Act.This study found that the Georgia- Pacific Log Pond contained elevated concentrations of mercury,phenolic compounds, and woody debris that exceeded State cleanup levels.In cooperation with the Washington Department of Ecology and the interagency Bellingham Bay Pilot Work Group,Georgia-Pacific developed the Whatcom Waterway Log Pond Interim Remedial Action and Habitat Restoration Project,in which approximately 43,000 cubic yards of clean navigational dredge material were placed on the Log Pond sediments between November 2000 and February 2001.The final total placed thickness of the Log Pond cap ranged from 0.5 feet along the cap perimeter(e.g.,adjacent to structures)to up to 10 feet within the interior of the project area.The combined capping and habitat restoration project also improved 5.6 acres of habitat within the Log Pond.Long-term monitoring of the cap is underway,and results of Year-1 monitoring are discussed,including:1) monitoring of seepage quality at the margins of the Log Pond cap to demonstrate protection of surface water;2)Sediment monitoring within the Log Pond to demonstrate cap stability and compliance with State cleanup levels;and 3)Biological monitoring within the Log Pond area to demonstrate ecosystem restoration and the protectiveness of the cap in controlling bioaccumulation exposures.