Abstract

  One means of storing or disposing of contaminated sediment extracted from water bodies is to place the dredged material onshore in repositories termed confined disposal facilities (CDFs). Typically, they are constructed of earthen material and occupy large areas hundreds of acres in size. During the filling of these diked enclosures the top surface of the dredged material mass is exposed to the atmosphere. This direct contact with air encourages the loss of volatile and semi-volatile chemicals from the upper surface layers. The objective of the project was to study the published literature on the subject of data and theoretical models that address the evaporative losses. The focus is on gathering the best available information in order to provide a basis of making quantitative projections of evaporative fluxes to air for estimating human exposures to these chemicals. Although the data and models are generally applicable to any CDF of similar design, the flux projections are specific to the Indiana Harbor Canal (INC) sediment and its chemical characteristics. Chemodynamics process models are in an advanced state of development with regard to chemical desorption, transport in porous media, and movement across the air-soil interface. Models are capable of quantifying many second generation processes, such as loosely and tightly bound fractions, humidity/moisture desorption enhancements, and air thermal stability in the atmospheric boundary layer (ABL) that are supported by theoretical arguments and observations. Two deterministic chemical release and transport models have been developed independently starting in the 1970's. Both efforts are founded on well established physical chemical principles quantifying processes through the use of Lavoisier's species mass balance on the soil column. Chemical specific flux data to air was located for 21 of the 24 volatile compounds identified as substances of concern in the proposed IHC CDF. A total of 232 flux values were located representing laboratory measurements, pilot-scale simulations, and field data. The data from these measurements was summarized by using chemical categories: polyaromatic hydrocarbons, pesticides, the benzene, toluene, xylene (BTX) group, metals, polychlorinated biphenyls (PCBs), and the dioxin/furans. The report contains a discussion of the measurements found in each category, the experimental techniques employed, and focuses on the quality of the measurements and model applicability to the IHC CDF situation.