The price of capping an area is always a tricky question to answer, as every project and site will have unique challenges that alter the costs significantly. Below is an example of a proposed capping project on the Anacostia River that highlights some of the key factors to consider when comparing reactive and conventional barriers. Cost estimates and conventional capping scenarios were published by the District of Columbia Interstate Commission on the Potomac River Basin.*

From these general cost estimates it can be seen that the use of reactive barriers may be equal to or less costly than conventional capping systems. The main reasons for these cost savings are reduced amounts of contaminated sediments required to disposed, and reduced volumes of capping material required to be transported.

*Velinsky, D.J., B. Gruessner, H.C. Haywood, J. Cornwell, R. Gammisch, and T.L. Wade. 1997. Determination of the Volume of Contaminated Sediments in the Anacostia River; District of Columbia; District of Columbia ICPRB Report #97-2. Interstate Commission on the Potomac River Basin, Rockville, MD.