EXECUTIVE SUMMARY (continued) 



shallow redox potential discontinuity (RPD) depths over the NHAV 93 mound as well as 

 the CLIS reference areas. As a result, lower than expected organism-sediment index (OSI) 

 values were found near the center and extreme southern and eastern stations despite the 

 presence of Stage III organisms at eleven of thirteen stations over the NHAV 93 mound. 



In September 1994, a disposal buoy marked "CDA" was deployed at 41°09.343' N, 

 72°53.099' W by SAIC to the northeast of the NHAV 93 mound. Approximately 

 129,900 m 3 of UDM was deposited at the buoy from late November through mid- 

 December 1994 to form the foundation of the CLIS 94 mound. At the conclusion of UDM 

 disposal operations, the CDA buoy was struck by a disposal barge and dragged off-station. 

 The buoy was repositioned to 41°09.334' N, 72°53.084 1 W before the start of CDM 

 deposition over the CLIS 94 mound. The UDM deposit was capped to a thickness of 0.5 

 to 1.0 m from January through May 1995 with an estimated volume of 161,000 m 3 of 

 CDM. The placement of the CLIS 94 mound approximately 630 m northeast of NHAV 93 

 began the formation of a second containment ring capable of accommodating a future CAD 

 mound project. 



Bathymetric data collected over the CLIS 94 mound exhibited a moderate sized, 

 stable, and completely capped feature of the CLIS seafloor. The new CLIS bottom feature 

 is approximately 470 m wide at the center with a mound height of 3.25 m at the apex. The 

 CLIS 94 mound has completely incorporated the CS-90-1 mound, a capped mound 

 developed during the 1989/90 disposal season. Benthic recovery of CLIS 94 was advanced 

 with Stage III organisms present at the majority of REMOTS® stations in spite of the 

 recent impact of disposal and added stress of seasonal hypoxia. 



The FVP mound is a small mound in the northeast corner of CLIS composed of 

 uncapped UDM dredged from Black Rock Harbor in the spring of 1983. It was formed as 

 part of an Environmental Protection Agency (EPA) and US Army Corps of Engineers, 

 Waterways Experiment Station (WES) joint effort to evaluate various dredged material 

 disposal alternatives. Since 1991, FVP has displayed instability in the benthic infaunal 

 population inhabiting the surface sediments. September 1995 REMOTS® results from FVP 

 continue to show a lack of a stable, healthy benthic environment with the presence of 

 depressed RPD and OSI values near the center of the mound. However, the effects of a 

 decrease in available oxygen on the organisms inhabiting FVP might be amplified due to 

 the preexisting stress of occupying a deposit of uncapped UDM. The FVP mound has 

 been monitored periodically as a source of comparison for other mounds at CLIS since its 

 formation in 1983. Now that the WES/EPA experimentation has concluded, capping of 

 the FVP mound in order to isolate the UDM from the marine environment is 

 recommended. 



