corridor that transects NLDS (NDA #4; Figure 1-3). No disposal was reported at the third 

 or fourth NDA buoy locations. 



In summary, during the 1991-1992 disposal season, a total of 8,800 m 3 of dredged 

 material was disposed at NDA buoy locations #1 and #2 (Appendix Al). A total barge 

 volume of 95,400 m 3 of sediment associated with the Dow/Stonington capping project was 

 deposited near the center of NLDS (Appendix A2). 



A small dredged material disposal mound, which did not require capping, was 

 formed at 41°16.577' N, 72°04.862' W. This mound (the NL-91 Mound) was formed 

 when 16,800 m 3 of dredged material suitable for unconfined open- water disposal was 

 released at the NDA 92 buoy between 6 February and 2 April 1993. 



Although the NDA-97 buoy was deployed in September 1997 at 41° 16.233' N, 

 72° 04.906' W (NAD 83) over the NL-94 mound area, disposal was actually directed to 

 capping points over the NL-91 and D/S mound complex during the 1997-1998 season in 

 order to augment the cap. DAMOS surveys conducted in 1992 and 1995 indicated that 

 although a layer of sand covered much of the original Dow/Stonington material, additional 

 cap material should be placed on the mound complex to ensure unsuitable material was 

 isolated from the marine environment. An estimated barge volume of 3,750 m 3 of suitable 

 sediment dredged from Shennecossett Yacht Club was deposited over the mound from 10 

 September 1997 to 9 April 1998. In addition, approximately 3,100 m 3 of dredged material 

 from Gales Ferry Marina was deposited at the capping points from 15 to 18 October 1997. 

 Buoys are not placed in this region to avoid potential obstruction of the 300-m wide 

 submarine transit corridor. Therefore, accurate disposal was dependent upon the 

 navigation to pre-determined points via GPS or LORAN-C. The total barge volume of 

 6,850 m 3 of CDM was placed in the northern region of the NL-91 and D/S mound 

 complex during the 1997-98 disposal season 1 . 



1.2.2 USCGA and NL-94 Disposal Mounds 



In January 1995, 43,500 m 3 of UDM was released at a USCG buoy (41° 16.490' N, 

 72°04.290' W). This material was then covered with 80,500 m 3 of capping dredged 

 material (CDM). The USCG buoy was located approximately 180 m west of the historic 

 NL-TR Mound apex. The USCGA Mound incorporated most of the NL-TR Mound's 



1 During the 1998-2000 disposal seasons, over 20,000 m 3 of CDM from a number of projects 

 was placed at the D/S mound to augment the cap. Monitoring of the D/S mound was 

 conducted during the summer of 2000, including bathymetric and REMOTS® surveys. The 

 results of these surveys will be published in a subsequent report. 



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



