The Ab and Oeb horizons at Sites A and B, respectively (Tables 4 and 5) exhibit a higher hydraulic conductivity than the SBDM and underlying soil, likely because of the relatively higher organic matter content.
The design of the SBDM containment areas, typical of other dredged material deposition sites in the Chesapeake Bay watershed, involves the creation of a diked off area that is ultimately filled with DM by hydraulic pumping.
This reaction and the reaction of the sulfuric acid with silicate minerals to release Al and other elements from the mineral structures are likely pathways for the release of iron, aluminum, and sulfuric acid from SBDM into the Pocomoke Sound.
During periods of drought, SBDM may act as reservoirs of acidity where additional sulfuric acid and acid-forming salts may form; however, in cases of above-normal rainfall, large quantities of low pH effluent carrying Fe, Al and other elements can be released from SBDM.
During periods of drought, oxidising conditions are presumed to prevail thereby favouring sulfide oxidation of the SBDM.