EXECUTIVE SUMMARY 



In July 1992, the Western Long Island Sound Disposal Site (WLIS) was surveyed as part 

 of the Disposal Area Monitoring System (DAMOS) Program. The survey was conducted to 

 assess the effects of recent disposal at the site as well as to revisit areas within the site and at the 

 reference areas that had showed evidence of disturbance based on results from the last survey in 

 June 1991. 



In June 1991, the monitoring survey at WLIS showed high sediment oxygen demand and a 

 high sulfide content at some monitoring stations on disposal mounds "A" and "D" where 

 dredged material had been released during the 1989/1990 disposal season. The survey also 

 indicated that reference area WLIS-REF may contain historical dredged material and that 2000S 

 had experienced frequent physical disturbance. In addition, 2000S contained patchy distributions 

 of elevated polycyclic aromatic hydrocarbons (PAHs). Recognizing that it is difficult to find 

 areas of western Long Island Sound that do not show some impact from human activity, it was 

 still determined that a search for more suitable references should be conducted. 



The July 1992 monitoring survey at WLIS addressed these two concerns as well as 

 determined the topography, areal extent, and recolonization status of the active mound WLIS 

 "F". Survey methods at the WLIS "F" mound included bathymetry and REMOTS® sediment- 

 profile photography. The bathymetric survey at WLIS "F" showed a mound approximately 200 

 m in diameter and 1.9 m in height. The thin layer of dredged material detected by REMOTS® 

 was within a circular area 350 m in diameter. The WLIS "F" mound had recolonized rapidly 

 with deep apparent redox potential discontinuity (RPD) values and Stage III infauna at the apex of 

 the mound. 



The benthic habitat and sediment toxicity studies for selected stations at mounds "A" and 

 "D" included REMOTS® sediment-profile photography and a 10-day amphipod bioassay. The 

 REMOTS® data at mound "A" and "D" indicated only modest improvement in habitat quality 

 since 1991. However, the 10-day bioassay test showed no statistical difference between these 

 sediments and those at the reference areas or control sediments. No remedial action is warranted 

 based on these observations, though periodic follow-up monitoring should continue. 



The search for reference areas to replace WLIS-REF and 2000S included a cross-shaped 

 bathymetric survey of areas named SOUTH and EAST to characterize the topography of these 

 proposed areas and a 13-station cross grid REMOTS® survey of each proposed site. These areas 

 were also sampled for metals, PAHs, grain size, and total organic carbon. The results showed 

 that SOUTH was a suitable replacement for 2000S. Area EAST was located too close to an 

 historic dredged material disposal site and showed some of the same characteristics as WLIS- 

 REF. 



