Table 2-1 



Portland Disposal Site Reference Areas 



Reference Areas 



Location 



Water Depth 



SEREF 



43°32.802' N 



70°00.193' W 



90 m 



SREF 



43°33.346' N 



70°01.753' W 



60 m 



EREF 



43°34.429' N 



69°59.732' W 



70 m 



In January 1992, as part of the USCG capping project, a 64-station orthogonal 

 REMOTS® survey around the disposal buoy mapped the distribution of dredged material at 

 PDS (Figure 2-1). Ambient sediment formed the western boundary of the dredged material 

 deposit in January, and hard rock was found in the northeast, leaving the location of the 

 dredged material boundary unclear on the east, and north and south (Figure 2-2). 



The REMOTS® stations surveyed in July were chosen to further define the boundaries 

 of the dredged material and to determine the status of benthic recolonization at the site. 

 Fourteen REMOTS® stations were surveyed on July 22 (Figure 2-3). Seven of these stations 

 (El, G2, F3, E4, H5, G7, E8) were also surveyed in January. The seven stations outside of 

 the boundary of the January survey (14, J5, 17, D9, 19, M9, E10) were surveyed to further 

 delineate the dredged material boundary. After reviewing the REMOTS® photographs from 

 these 14 stations for the presence of dredged material, an additional 28 REMOTS® stations 

 were sampled to demarcate further the dredged material boundary and to gain more 

 information on benthic recolonization on the cap. 



2.3 Sediment Density 



A 24 kHz acoustic survey was conducted concurrent with the July 21 bathymetric 

 survey. The survey interfaced the 24 kHz sound source with the Acoustic Core System® 

 (model CE-IB-100; Caulfield Engineering Group, Oyama, BC, Canada). The Acoustic Core 

 System® is a combination hardware/software package designed to provide quality control 

 during shallow seismic data acquisition. It provided acoustic impedance and density 

 predictions based on signal amplitude in the shallow seismic field. The system calculated 

 impedance values relative to seawater, and generated density estimates based on the work of 

 Hamilton (1970, 1971). Surface sediment grab samples were collected to ground truth 

 sediment density estimates. 



Monitoring Cruise at the Portland Disposal Site, July 1992 



