Air emission flux from contaminated dredged materials stored in a pilot-scale confined disposal facility

A pilot-scale field simulation was conducted to estimate the air emissions from contaminated dredged material stored in a confined disposal facility ( CDF). Contaminated dredged material with a variety of organic chemicals, ob tained from Indiana Harbor Canal, was used in the study. It was placed in a n outdoor CDF simulator (i.e., a lysimeter of dimensions 4 ft x 4 ft x 2 ft ): A portable, dynamic flux chamber was used to periodically measure emissi ons of various polynuclear aromatic hydrocarbons (PAHs). A weather station was set up to monitor and record the meteorological conditions during the e xperiment. The fluxes of several PAHs were monitored over time for 6(1)/(2) months. Initial 6-hr average fluxes varied from 2 to 20 ng/cm(2)/hr for si x different PAHs. The flux values declined rapidly for all compounds soon after placement of the dredged material in the CDF Chemical concentrations derived from flux v alues were generally of low magnitude compared with ambient standards. Data obtained from the experiment were compared against those predicted using m odels for air emissions. Model simulations showed that initially the flux w as largely from exposed pore water from saturated (wet) sediment, whereas t he long-term flux was controlled by diffusion through the pore air of the u nsaturated sediment. Model predictions generally overestimated the measured emissions. A rainfall event was simulated, and the dredged material was re worked to simulate:that typical of a CDF operation. Increased flux was obse rved upon reworking the dredged material.