1.2 Seawolf Disposal Mound 



In September 1997, Science Applications International Corporation (SAIC) 

 conducted a master bathymetric survey at the NLDS (Figure 1-2). The master bathymetric 

 survey provides a reference frame for locating the disposal and monitoring activities 

 conducted from 1991-1998. The disposal history of each mound complex has been 

 described in Volume I of this report (SAIC 2001). The disposal history of the U.S. Navy 

 Seawolf Mound is described below, followed by a summary of monitoring activities. A 

 timeline of all activities associated with the Seawolf Mound (Figure 1-3) has been provided 

 to summarize the events; details of the survey methods are provided in Section 2.0. 



The September 1997 master bathymetric survey also marked the conversion from the 

 horizontal navigational reference system of the North American Datum of 1927 (NAD 27) to 

 the North American Datum of 1983 (NAD 83) for all future bathymetric surveys conducted 

 at this site (see Methods section). 



1.2.1 U.S. Navy Seawolf Disposal Activity 



The decision by the U.S. Navy to homeport Seawolf class submarines in Groton, CT 

 required deepening of the federal navigation channel and berthing areas in the Thames River to 

 provide safe navigational depth for submerged transit (Maguire Group, 1995). Permits were 

 issued in 1995 to dredge the channel and berthing areas and deposit the materials at NLDS. 

 The work was completed during the 1995-1996 dredging season (September-May). Disposal 

 of maintenance work (material dredged within an authorized depth) and new work (material 

 dredged to a newly authorized depth) resulted in a total estimated disposal volume of 

 877,500 m 3 of sediments. 



The first portion of the project, an approximate barge volume of 305,200 m of UDM 

 originating primarily from the New London Naval Submarine Base (Piers 8, 10 [and 17 under 

 a separate permit]) and the Thames River navigational channel (a 1.92 km reach north of 1-95 

 bridge), was deposited at a temporary buoy labeled "Navy" deployed by the U.S. Navy at 41° 

 16.506' N, 72° 04.797' W (41° 16.500' N, 72° 04.826' W, NAD 27). In addition, 800 m 3 of 

 UDM from a separate project in the Mystic River (Mystic Seaport) was disposed at the Navy 

 buoy prior to capping operations (Figure 1-3). Following the placement of UDM, capping 

 operations began. Between 8 December 1995 and 31 January 1996, an estimated barge volume 

 of 556,000 m 3 of CDM dredged from the Thames River channel was placed over the Seawolf 

 Mound area, yielding a 1.82 to 1.0 CDM to UDM ratio. 



Monitoring Cruise at the New London Disposal Site, Seawolf Mound 1995 - 1998 



