70 



Core X, obtained 150 m southwest of the NHAV 93 mound center, penetrated 

 200 cm into the NHAV 93 mound. According to the November 1993 and March 1994 

 bathymetry, the area surrounding Core X received approximately 1.25 m of UDM and 

 0.5 m of CDM (Figure 3-29). The subbottom data indicated the presence of approximately 

 1 .0 m of cap material overlaying 2.25 m of UDM and historic dredged material (Figure 3- 

 30). Upon extrusion. Core X displayed a layer of capping material 90 cm thick over a 

 deposit of New Haven UDM that extended an additional 1 10 cm to the penetration limit 

 (Figure 3-32B). 



Core Y was acquired approximately 100 m northeast of the NHAV mound center, 

 and penetrated 205 cm into the sediment. The results of the bathymetric data processing 

 suggest that a layer of CDM was placed over a 0.75 m thick UDM deposit. The 

 subbottom profiler detected 0.25 m of CDM over 3.0 m of New Haven UDM and historic 

 dredged material. During the processing of Core Y, a small lens of sand was discovered at 

 27 cm of penetration, confined by layers of black clayey silt (Figure 3-17). The X-Star 

 system detected the sand layer as a change in sediment density and tracked it as the 

 CDM/UDM interface reflector. As a result, the subbottom profiler quantified less capping 

 material than was acmally present. Core Y shows the CDM/UDM interface at 

 approximately 90 cm of penetration with UDM sampled to approximately 1 80 cm of 

 penetration (Figure 3-33A). 



Core Z, collected approximately 110 m northwest of the NHAV 93 mound center, 

 penetrated the seafloor to a depth of 250 cm. According to the 1993-1994 bathymetric 

 analysis, the area surrounding Core Z received 1.25 m of New Haven project UDM and 

 was capped to an unknown CDM thickness (Figure 3-29). The subbottom profiler 

 successfully quantified the cap thickness as 0.75 m during the July 1994 survey. In 

 addition, the UDM and historic dredged material thickness in the vicinity of Core Z were 

 determined to be 3.75 m (Figure 3-30). The description of Core Z characterized the top 

 80 cm of sediment as New Haven capping material. New Haven Harbor UDM was 

 sampled from 80 cm to 215 cm with historic dredged material from CLIS 87 extending 

 from 215 cm to the penetration limit (Figure 3-33 A). 



Core Zl was obtained approximately 100 m southeast of the mound center and 

 penetrated 143 cm into the NHAV 93 sediments. Calculations based on successive 

 bathymetric surveys detected approximately 2.5 m of UDM and an unknown thickness of 

 CDM in the area surrounding Core Zl (Figure 3-29). The X-Star system calculated the 

 thickness of the CDM as a layer approximately 0.75 m thick. The UDM/historic dredged 

 material deposit was found to be 2.5 m thick (Figure 3-30). The analysis of Core Zl 

 found CDM composing the top 70 cm of sediment, with underlying layers of New Haven 



Harbor UDM extending down the core 73 cm to the penetration limit (Figure 3-34). 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1994 



