Synthesis of Monitoring Surveys at the Cornfield Shoals Disposal Site, July 1991 to May 1992

Synthesis of Monitoring Surveys at the Cornfield Shoals Disposal Site, July 1991 to May 1992
Author: Mary Baker Wiley
Publisher:
Total Pages: 66
Release: 1996
Genre: Dredging
ISBN:

Preliminary evidence of active bed transport at the Cornfield Shoals Disposal Site (CSDS) prompted the National Marine Fisheries Service and Connecticut Department of Environmental Protection to express concern about possible sediment transport towards, and impact on, shellfish beds located north of the site, north of Long Sand Shoal. This preliminary study was designed to determine if the field-observed transport at the disposal site is consistent with the predicted east-west transport pattern found in the historical record. This investigation at CSDS between July 1991 and May 1992 provided strong circumstantial evidence for active bed transport. his study included a series of bathymetric surveys, current meter suspended sediment data collection, and REMOTS(R) photography of the sediment-water interface. The circumstantial evidence for active bed transport included shifts in areas of sediment accumulation and erosion, increased suspended sediment deposits at the sediment-water interface. In general, active bed transport appears to follow the historical east-west current direction, and the extent of the transport depends on the type of material. The actual direction and magnitude of active bed transport apparently depend on local topography and the nature of materials being transported. Sediment accumulated over a broad area near the disposal points of sand hydraulically dredged from the Connecticut River in September 1991. Subsequent bathymetric surveys showed apparent movement of this material to the west. A clearly defined deposit formed at the disposal point for fine-grained material mechanically dredged from North Cove, Connecticut.