11 



Bingham Oceanographic Laboratory (Riley 

 1952, 1956, 1967). In the 1970s the 

 disposal site and several adjacent areas 

 used as reference or control stations were 

 extensively surveyed as part of initial 

 studies required by the Clean Water Act to 

 detail environmental effects associated with 

 dredged material disposal (Gordon et al. 

 1972, Rhoads 1973, Bohlen and 

 Tramontano 1974a,b). In addition, these 

 surveys provided a basis for a variety of 

 research studies detailing the physical, 

 chemical, and biological characteristics of 

 the central Sound, relating them to the 

 more general class of estuaries or coastal 

 embayments (e.g., Gordon and Pilbeam 

 1975, Turekian et al. 1980, McCall 1977, 

 Rhoads et al. 1979, Saltzman 1980). 

 These data provide a valuable baseline 

 supplementing the data sets obtained by the 

 monitoring surveys conducted as part of 

 the individual capping projects. 



2.2 Stamford-New Haven 



The first planned capping operation 

 conducted by NED was the Stamford-New 

 Haven (STNH) project which began in 

 1979. High concentrations of selected 

 heavy metals were measured in the 

 sediments of the upper reaches of 

 Stamford Harbor, which caused a delay in 

 maintenance dredging. Sediment 

 deposition and infilling proceeded to a 

 point where navigational access for 

 commercial vessels was limited to high 

 tide periods. 



Sedimentation was particularly 

 pronounced within the east branch of the 

 upper harbor (Figure 2-2), an area dredged 



previously in 1942. Field surveys of the 

 area conducted by NED personnel in 1978 

 indicated that restoration to the authorized 

 channel depth in this area would require 

 removal of approximately 50,500 m 3 of 

 sediment. More detailed surveys 

 conducted just prior to dredging resulted in 

 an upward revision of this estimate to 

 approximately 58,100 m 3 . 



Laboratory analyses indicated that the 

 majority of sediments to be dredged from 

 Stamford Harbor were fine-grained silts 

 and clays with elevated levels of oil, 

 grease, and volatile organics. In addition, 

 they contained moderate to high 

 concentrations of a variety of heavy metals 

 including lead (Pb), zinc (Zn), mercury 

 (Hg), and copper (Cu; Table 2-1). Based 

 on these physical and chemical data, the 

 sediments were characterized as highly 

 contaminated according to the New 

 England River Basin Commission 

 (NERBC) guidelines used by NED and the 

 States of Connecticut and New York at the 

 time (Table 2-2; NERBC 1980). These 

 data, in combination with laboratory 

 bioassays that identified a potential for 

 adverse biological effects (Moore 1978), 

 indicated that special procedures would be 

 required if the material was to be 

 deposited at an open- water site. 



To satisfy these special handling 

 requirements, NED proposed open- water 

 disposal of the Stamford sediments at 

 CLIS with the resulting deposit to be 

 capped by material dredged from New 

 Haven Harbor (US ACE 1978). These 

 latter sediments were to be obtained from 

 several locations along the main stem of 



Sediment Capping of Subaqueous Dredged Material Disposal Mounds 



