Effects of a Clay Cap on Contaminants



MRRI, Seton Hall University, Fairleigh Dickinson University & AquaBlok Ltd.

Project Summary


As a result of agricultural, commercial and industrial activities conducted in the absence of environmental regulations and enforcement in the past, sediments contaminated by organic compounds, heavy metals, and other potentially toxic chemicals have accumulated in many of the world’s deepwater and wetland environments. These sediment-borne contaminants can eventually become incorporated into aquatic food webs and adversely affect ecological receptors like benthic organisms and fish, and ultimately pose a risk to human health. This project investigated a new in situ capping technology that could be used to remediate and/or manage contaminated sediments. AquaBlok (AB) is a patented, composite-aggregate technology comprised of a solid core, an outer layer of clay material, and polymers. When placed in water and over sediment, AB hydrates forming a layer between contaminants in sediment and the overlying water. Other materials – such as organic matter or plant seeds – can be incorporated into the AB as needed. Kearny Marsh in the NJ Meadowlands was chosen as the site for the field study because it has been chronically contaminated by landfills, leaching and run-off. The study design involved five treatments done in duplicate. The treatments were as follows:

Each of the 10 plots was approximately 60 by 60 feet. AB was placed in the marsh by a “stone-flinger” between July 25th and August 3rd of 2005. The study site proved too deep for optimal germination of aquatic plants. Biologs platforms measuring approximately 8’ X 20’ were created and sunken to provide a more suitable depth for plant germination.

Pre and post capping monitoring was conducted on the water quality, sediment quality and benthic macroinvertebrates (BMI) for selected heavy metals as well as organics.

Scientific Questions




Water quality

Chemicals of concern in water

Chemicals of concern in sediment

Benthic macroinvertebrates

Marsh vegetation




Data files

Final Report

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