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6.5 PORTLAND DISPOSAL SITE 



6.5.1 Summary of PDS 



The Portland Disposal Site (PDS) is located in Bigelow Bight approximately 7.1 nmi 

 east of Dyer Point, Cape Elizabeth, Maine. The site is a 1 nmi 2 area centered at 

 43°34.100' N, 70°2.000' W (Figure 6-33). The site is characterized by a flat, sandy valley, 

 surrounded by rocky outcrops, with water depths ranging from 41 to 62 m (Figure 6-34). 

 Current velocities at PDS are the least energetic of all disposal sites monitored under the 

 DAMOS program and are influenced primarily by a nontidal, southerly flow averaging 5-6 

 cm-s" 1 . The average peak flow of tidal-induced currents is approximately 8 cm-s" 1 in a 

 northwest-southeast direction. Unlimited fetch to the south and southeast, combined with 

 strong gale force winds in the winter, may produce wave-induced currents. However, the 

 deeper portions of the site would experience a minimum of storm-induced energy as 

 compared to the shallower outcrops (SAIC 1988a). 



Commercial finfishing within the disposal site is limited due to the rough and rocky 

 bottom topography and the resulting increased possibility of "hanging up" trawling gear; 

 however, bottom gill nets are set along the edge of the site in winter and spring. The site is 

 about 1 nmi shoreward of an important trawling area which yields a variety of finfish 

 including dab, gray sole, and flounder in the summer and cod, haddock, and other 

 groundfish in the winter. With the exception of the Atlantic herring, all commercially 

 important fish in the area have buoyant eggs or spawn in the estuaries. Most of the lobster 

 fishing takes place in the waters shoreward of West Cod Ledge during the summer months; 

 however, some lobsters are caught at the disposal site following migration out of the cooler 

 shallow waters between November and April (SAIC 1988a). 



6.5.2 PDS: 1989 Monitoring Results 



Since 1984, one monitoring survey has been conducted at PDS (SAIC 1990j). The 

 objectives of this January 1989 survey were to map the distribution of dredged material 

 deposited since the May 1984 survey and to assess the status of benthic recolonization. The 

 distribution of dredged material was determined acoustically where the disposal mound was 

 greater than 30 cm. REMOTS® sediment-profile photography was used to delineate the 

 extent and thickness of dredged material <20 cm. In addition, REMOTS® photography was 

 used to observe the status of benthic recolonization in the disposal area (SAIC 1990f). 



PDS received an estimated 47,000 m 3 of dredged material between 1985 and 1989 

 (Figure 6-35). In 1984, the bathymetric survey around the disposal buoy location detected a 

 distinct dredged material mound. The 1989 bathymetric survey covered the area surveyed in 

 1984 as well as the area around the 1989 buoy location to the north. The 1984 disposal 

 mound remained stable at 49 m water depth from 1984 to 1989. The 1989 bathymetric 



DAMOS Summary Report, 1985-1990 



