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More Detailed Map
Reference Site Location
The Portland Disposal Site (PDS) is one of three
regional dredged material disposal sites located in the waters of Maine. It covers
a 1 nmi2 (3.4 km2) area of seafloor centered at 43° 34.105'
N, 70° 01.969' W (NAD 83), approximately 7.1 nmi (13.2 km) east of Dyer Point,
Cape Elizabeth, Maine. PDS is characterized by a rough, irregular bottom topography,
with areas of soft sediment accumulation in the basins among bedrock outcrops.
Sediments deposited at PDS have originated from dredging projects in Portland
Harbor, Fore River, and many of the smaller rivers and harbors within the Casco
Bay region. A total of 1,400,000 yd3 has been disposed of at this site
since 1982. In recent years, there has been significant DAMOS monitoring activity
at this site, as part of a comprehensive subaqueous capping feasibility study.
The depositional environment of PDS, especially within the deeper fine-grained
basins, indicates that volumes of dredged material can be placed without significant
subsequent movement beyond the disposal site boundaries. Dredged material disposal
operations specifically target these natural basins to form mounds of sediment on the seafloor. The various bedrock ridges surrounding the depositional areas provide a measure of protection from wave energy and thus act to contain the deposited dredged material. The steep sides of the depressions or hollows disrupt any near bottom orbital currents generated by passing storm waves, minimizing resuspension over the surface of the sediment deposit. In addition, the rock walls of the natural seafloor features prevent the lateral spread of non-cohesive sediment on the seafloor as a dredged material mound is developed over time.
Check out site data! Annual Disposal Volumes
Bathymetry Dredged
Material Thickness Sediment
Profile Images
Relevant DAMOS Reports:
No.
153: Dredged Material Fate Study at the Portland Disposal Site,
1998-2000
(full report available)
No.
140: Monitoring Survey at the Portland Disposal Site, August
2001 (full report available)
No. 136: Monitoring Cruise at the Portland Disposal
Site, Summer 2000 No. 123: The Portland Disposal Site Capping Demonstration
Project 1995-1997 (executive
summary available)
No. 122: A Predictive Model for Sediment Transport
at the Portland Disposal Site, Maine (executive
summary available)
No. 121: Oceanographic Measurements at the Portland
Disposal Site During Spring of 1996 (executive
summary available)
No. 108: Monitoring Cruise at the Portland Disposal
Site, July 1992 (executive summary
available)
No. 78: Monitoring Cruise at the Portland Disposal Site, January
1989
No. 46: Disposal Area Monitoring System (DAMOS) Annual Report, Summary
of Program Results, 1981-1984
No. 43: DAMOS Mussel Watch Program, Eastern
Long Island Sound Disposal Site and Portland Disposal Site Monitoring Projects,
1979-1981 DAMOS Annual Data Report, 1978 |
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