EXECUTIVE SUMMARY 



Under the Disposal Area Monitoring System (DAMOS) Program, Science 

 Applications Intemational Corporation (SAIC) conducted an environmental monitoring 

 survey at the New London Disposal Site from 10 to 13 August 2000. Field operations were 

 concentrated over the Seawolf and US Coast Guard Academy (USCGA) disposal mounds, as 

 well as the New London 1991 (NL-91) and Dow/Stonington (D/S) Mound Complex. The 

 August 2000 field effort consisted of collecting precision bathymetric and Remote 

 Ecological Monitoring of the Seafloor (REMOTS®) sediment-profile photography data. 

 These survey techniques were used to determine whether there were any significant changes 

 in seafloor topography over the Seawolf Mound or the NL-91 and D/S Mound Complex, as 

 well as to characterize the benthic recolonization status of all three of the surveyed dredged 

 material disposal mounds. 



The NL-91 and D/S Mound Complex is a historic sediment deposit on the NLDS 

 seafloor located within the US Navy submarine corridor established near the center of the 

 disposal site. This subtle bottom feature is composed of material dredged and disposed 

 during the 1991 and 1992 disposal season. Several previous REMOTS® sediment profile 

 photography surveys have served to demonstrate that the mound complex has been 

 successfully recolonized by benthic organisms since its creation in 1992, while previous 

 bathymetric surveys have indicated a need to increase the thickness of the capping dredged 

 material (CDM) layer over the mound complex. Since the 1996-97 disposal season, over 

 30,000 m^ of supplemental CDM has been placed over the NL-91 and D/S Mound Complex 

 as a part of a cap augmentation plan. 



The August 2000 bathymetric survey showed a detectable depth difference over the 

 NL-91 and D/S Mound Complex relative to September 1997. Accumulations of sediment up 

 to 0.5 m thick were attributed to the placement of supplemental CDM at several 

 recommended capping points. The recently-placed, supplemental CDM also was apparent in 

 the majority of the REMOTS® sediment-profile images obtained over the NL-91 and D/S 

 Mound Complex in August 2000. The REMOTS® images served to demonstrate that the 

 footprint of the supplemental CDM deposit completely covered the original unacceptably- 

 contaminated dredged material (UDM) deposit. These images also showed that the 

 supplemental CDM had been colonized successfully by a benthic community comprised of 

 both Stage II and Stage III organisms. 



The Seawolf Mound was developed in the northwest quadrant of NLDS during the 

 1995-96 disposal season by the placement of 877,500 m^ of dredged sediment emanating 

 from three separate projects in the eastem Long Island Sound region (Seawolf, Venetian 

 Harbor, and Mystic River). Dredging and disposal operations were tightly controlled to 

 create a single capped disposal mound, the U.S. Navy Seawolf Mound, consisting of 

 306,000 m^ of UDM and 571,500 m^ of suitable CDM. In addition to the multiple 



