Subaqueous Cap Design: Selection of Bioturbation Profiles, Depths, and Process Rates

摘要

When dredged material has been determined to contain contaminants that open-water placement would potentially cause to degrade the benthic environment, subaqueous capping with a layer of clean material may provide an acceptable management alternative. Subaqueous capping of in situ contaminated sediments also represents a potentially effective remediation option. For either practice to satisfy the requirement of isolation of the contaminated sediments, design of caps of clean material must account for multiple factors affecting the long-term stability of the cap. The purpose of this technical note is to present guidance on one of these factors, bioturbation, which consists of various processes whereby organisms modify sediment properties or move sediment particles or solutes within the sediment matrix. Specifically, this technical note focuses on estimation of bioturbation profiles, depths, and process rates in relation to subaqueous cap design.