Abstract: Dredging and Spoil Disposal in Chesapeake Bay, 1975-2025
M. Grant Gross, William B. Cronin
Dredging of navigation channels and port facilities in Chesapeake Bay is required in shoal-water areas of the turbidity maximum, at the bay entrance, and in harbors. Approximately 106 cu m/year is expected to be removed from northern Chesapeake Bay and a comparable amount from Baltimore Harbor. About 4 × 106 cu m/year of sediment will be dredged from the Bay entrance and the harbor at Hampton Roads, Virginia. Deepening of channels to 50 ft (16 m) at Baltimore and 55 ft (18 m) at Hampton Roads will average 6.8 and 2 × 106 cu m/year respectively during this period. Data for Baltimore Harbor indicate that dredging between 1925 and 1975 averaged 106 cu m/year for maintenance, 0.5 × 106 cu m/year for new cha nel construction.
Sources of dredged materials are not known. River-sediment discharge to the bay is probably 5 to 10 × 106 tons (15 to 30 × 106 cu m/year) per year, in the absence of major floods. Smaller but unknown amounts are contributed by sewage-treatment plants, urban runoff, industrial plants, and shoreline erosion.
Effects of dredged material disposal in the Bay also are poorly known. Available data suggest mostly localized and transitory effects for unpolluted materials. Because of public pressure, polluted materials are discharged to near-channel sites in harbors or to diked disposal areas.
Because of the shortage of wetland-disposal sites, opposition to open-water disposal, and high costs of diked disposal, new disposal sites and techniques probably will be needed in the next 50 years to handle the disposal of materials from needed dredging in Chesapeake Bay. Dredging and disposal will continue to be a major geologic process in Chesapeake Bay.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC