EXECUTIVE SUMMARY 



This report presents a synopsis of relevant background 

 information on baseline conditions at the Buzzards Bay Disposal 

 Site (BBDS) as of March 1990. Disposal records indicate that since 

 1979, 92,000 m 3 of dredged material consisting of relatively 

 uncontaminated sands and silty-sands have been disposed at the 

 site. Monitoring activities at the site have not been conducted by 

 the DAMOS program over the past several years, because the site has 

 been used infrequently. The largest collection of site-specific 

 data was gathered by Germano et al. , (1989) in 1981, and regional 

 data have been summarized in an earlier report (SAIC, 1989a) . 



From 27 to 29 March 1990, field operations were conducted at 

 BBDS to provide information on the effects of past disposal 

 operations. Field operations included a precision bathymetric 

 survey, REMOTS® sediment profile photography, and sediment sampling 

 for benthic, chemical, and physical analyses. The overall 

 objective of the cruise was to characterize existing bathymetric, 

 sediment grain size, sediment chemistry, and benthic conditions at 

 and around the disposal site. Three reference areas were selected 

 to provide comparisons between ambient and on-site conditions and 

 were located 3107 m northwest, 3940 m west, and 2600 m southwest of 

 the disposal site center. 



The information obtained from the bathymetric survey and 

 REMOTS® photos permitted the detection of two disposal mounds 

 within the surveyed area. The primary mound was central to the 

 disposal site, 1.2 m high and 60 m wide. The other, south and west 

 of the center mound, was 1.6 m high and approximately 90 m wide. 



The major modal grain size over the surveyed area ranged from 

 medium sand (2-1 phi) to silt-clay (>4 phi) . All stations 

 containing a major mode of medium (2-1 phi) and fine (3-2 phi) sand 

 fractions were rippled. The distribution of the major modal grain 

 size, as deduced from REMOTS® photographs, indicated a net bedload 

 sediment transport of fine-grained material to the southeast along 

 an 11.6 m isobath. Currents are most likely the dominant force 

 contributing to the transport. The disposal site center consisted 

 of rippled bedforms and fine sands which limited penetration by the 

 REMOTS® camera. 



The species composition found in this study was similar to 

 that of benthic communities in Cape Cod Bay and Boston 

 Harbor /Massachusetts Bay. Species richness was somewhat higher at 

 the reference stations; however, both on-site and off -site stations 

 were well within the range observed in soft-bottom, shallow water 

 environments. Significant differences existed between reference 

 stations and on-site stations in REMOTS® parameters for RPD depth, 

 successional stages, and OSI values. 



