Wykchoff/Eagle Harbor capped site

CHARACTERIZATION OF CONTAMINANT TRANSPORT POTENTIAL THROUGH IN PLACE SEDIMENT CAPS
Investigators: Victor Magar (Battelle), Upal Ghosh (UMBC), Marc Mills (EPA), Criag Jones (Sea Engineering), Brenda Bachman (USACE)
Duration: October 2004 - December 2007.
Funding agency: Strategic Environmental Research and Developmental Program (DoD)

Background. By isolating contaminated sediments, capping can effectively reduce exposure to contaminants and the possibility of contaminant transport into the food chain. However, because contaminated sediments are left in place, caps generally require long-term monitoring, and the risks of contaminant transport or sediment resuspension persist. Many contaminated marine sediment sites reside in shallow, coastal areas that are often impacted by advective processes (i.e., groundwater flow, tidal pumping, and wave pumping), sorption controlled diffusive processes, and bioturbation. These forces contribute to the total flux of contaminants through sediments and ultimately through a sediment cap. A theoretical foundation for contaminant transport through surface sediments exists, but remains untested for sediment caps exposed to advective forces. The scientific and engineering principles of capping need to be improved by testing and validating this theoretical foundation, and by establishing design criteria that account for processes that govern vertical contaminant migration through sediment caps.

Research Objectives. The primary objective of this project is to develop and improve engineering tools for more cost effective and efficient cap designs by enhancing the scientific understanding of contaminant transport through sediment caps. The study will use innovative field and laboratory tools, analytical techniques, and numerical modeling to build on the current knowledge of contaminant transport through caps. Specific goals will be to examine contaminant transport over time at two existing DoD owned or operated sites and to quantify aqueous contaminant transport and the processes that govern contaminant transport. This will be done by measuring porewater advection, contaminant concentration profiles over time, and laboratory measurements of contaminant transport processes. The laboratory component will involve experimental columns to study contaminant migration through physical models of caps under advective conditions. The columns will be operated to simulate and accelerate field conditions, using contaminated sediment and clean cap materials. The study will also examine conventional and innovative cap materials.