1J1_ 



5.4 NL-94 Mound 



• The NL-94 Mound was formed in 1994-1995 from 37,000 m 3 of material from the 

 U.S. Navy Submarine Base. Approximately 28,200 m 3 of CDM was placed over 

 8,700 m 3 of UDM creating a mound 125 m wide and 0.9 m high. A tongue of 

 dredged material 20-40 cm thick extended 140 m southeast from the mound apex. 



• REMOTS® sediment profile results in 1995 indicated that the capped mound was 

 supporting a healthy benthic community. This represented faster recovery than 

 expected. Some stations showed evidence of impact from low dissolved oxygen or 

 organic enrichment, but this was also seen at the reference areas and is attributed to 

 regional conditions of stress. 



• Additional suitable material was placed in 1996-1997 to the west of the NL-94 Mound 

 at the NDA-96 buoy. The NL-94/96 Mound complex forms a flat ridge in the western 

 center of the NLDS between the southern edge of the Seawolf Mound and the 

 northern edge of NL-I. 



• REMOTS® sediment profile results in 1997 indicated that the new dredged material 

 was supporting a healthy benthic community and recovered more quickly than 

 expected. 



5.5 Northern Region 



• The master bathy metric survey conducted in 1997 extended into an area termed the 

 Northern Region to provide baseline characterization. The plateau and apron of the 

 Seawolf Mound extended into this region, indicated by both bathymetric and 

 REMOTS® data. Historical dredged material was detected in the Northern Region 

 and can be related to pre-DAMOS disposal in the vicinity of the NL-RELIC 

 Mound. The older age of this disposal activity is reflected in a higher successional 

 status compared to the reference areas, for both ambient sediments and historical 

 dredged material. 



5.6 Recommendations 



• The capped mound formed at Dow/Stonington should receive additional material to 

 ensure sufficient cap distribution (50 cm) over all UDM placed at these sites. 

 Following placement of additional CDM, monitoring of the mounds should include 



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



