|
Dredged material consists of sediments—clay, silt, and mud— that are cleared from the bottom of shipping channels in the Chesapeake Bay and its rivers.
Bottom sediment throughout the Bay region has been affected by human activities. The effects vary depending on where the sediment is located and how it has moved through time.
Intense industrial activity, before the era of environmental regulations, left a legacy of contaminated sediment in the Baltimore Harbor. Elsewhere, fertilizers, oil, pesticides, and other pollutants that wash into the water are often present in Bay sediment. While far from pristine, most Bay sediment is still considered “clean”—that is, without levels of pollutants that could harm human health or wildlife. When clean sediment is removed from shipping channels, it can be used for other purposes.
One of the most successful examples is on Poplar Island in the mid-Bay, where engineers and scientists are using clean dredged material to rebuild the severely eroded island, restore wetlands, and create wildlife habitat. Poplar Island is an example of the “beneficial use” of dredged material, the state’s preferred management option.
Some sediment dredged from the Baltimore Harbor is considered contaminated. State law requires that all harbor material placed beyond the harbor itself must be contained within a “confined disposal facility.”
A confined disposal facility consists of a diked area constructed in open water, along a shoreline, or at an upland site. The dikes prevent the dredged material from mixing with the surrounding environment. Spillways, which release excess water back to the Bay or river, are constantly monitored to ensure that the released water meets both health and environmental standards. Confined disposal facilities are in use at Hart-Miller Island and Cox Creek.
|
