28 



2.2.1 NL-91 and the Dow/Stonington (D/S) Mound Complex 



The NL-91 and D/S Mound complex was developed as part of a dredged material 

 capping project during the 1991-92 disposal season. These mounds were first monitored 

 using REMOTS® sediment-profile photography in August 1992. Three replicate 

 photographs were collected at each of 41 REMOTS® stations radially distributed around 

 the NDA-91-2 buoy position (Figure 2-4 A; Table 2-4). The name of each station in Figure 

 2-4 represents its distance (in meters) from the center (CTR) station. Many of these 

 stations extend out to historic disposal mounds placed during the last three decades. 



Follow-on surveys (1995, 1997, and 1998) focused primarily on the D/S sediment 

 deposit. As a result, the survey grid was modified to evaluate the recovery of the capped 

 mound. A cross-shaped, 13-station REMOTS® grid was established over the capped 

 mound and centered at the D/S buoy position (41° 16. 160' N, 72°04.470' W; NAD 27; 

 Figure 2-4B). Once again, three replicate photographs were obtained at each REMOTS® 

 station. 



This smaller, 13-station REMOTS® grid was re-occupied in 1997 and 1998, 

 replicating the August 1995 monitoring activity. The change in positioning systems and 

 horizontal control (NAD 27 to NAD 83) resulted in a change in the units of the survey 

 center (41° 16.168' N 72° 04.439' W; NAD 83; Table 2-4). However, there was no 

 alteration of the REMOTS® survey grid relative to seafloor features and operations 

 performed in previous years, only a change in the reported coordinate system 

 (Figure 2-4B). 



2.2.2 USCGA Mound 



The USCGA mound was first examined using sediment-profile photography in 

 August 1995. A 13-station, cross-shaped grid, with a southeast extension, centered at 

 41° 16.480' N, 72°04.290' W (NAD 27) was established over the USCGA mound 

 (Figure 2-5; Table 2-5). Due to the findings of the August 1995 effort, no follow-on 

 surveys were conducted in 1997 or 1998. 



2.2.3 NL-94 Mound 



The NL-94 mound was subjected to detailed investigation using REMOTS® 

 sediment-profile photography in August 1995 and September 1997. A 15-station, modified 

 radial grid centered on the NDA-94-1 buoy position (41°16.240' N, 72°04.890' W; NAD 

 27) was established over the NL-94 mound. The REMOTS® stations extended up to 150 m 



Monitoring Cruise at the New London Disposal Site, 1992 - 1998 



