EXECUTIVE SUMMARY 



Science Applications International Corporation (SAIC) conducted a reconnaissance 

 REMOTS® sediment-profile and plan view photographic survey of the Boston Lightship 

 Disposal Site (BLDS) from 9 to 11 August 1994. From the 1940s to 1976, when disposal 

 stopped at BLDS, a majority of the Boston area's dredged material and other debris had 

 been released at the site. The last recorded disposal at the site was in 1976 when about 

 8,000 m 3 were disposed. The REMOTS® sediment-profile and plan view photographic 

 stations were located to examine possible historic dredged material that had been identified 

 in a 1991 side-scan sonar survey of the area. The 1994 surveys were conducted as part of 

 a long-term effort to examine historical disposal areas to determine whether remediation 

 activity is recommended. The assessment of the REMOTS® and plan view data, in 

 conjunction with the 1991 side-scan results, determined that remediation at the site was not 

 necessary. Recolonization of old dredged material has been extensive. The benthos in the 

 areas sampled was populated by a diverse community composed of Stage II and Stage III 

 organisms representing a healthy benthic habitat with OSI values >6. No difference was 

 observed between the historic dredged material and the ambient sediment. In light of the 

 healthy benthic habitat, only periodic monitoring is recommended. Sediment samples were 

 collected at BLDS in 1994. They were archived and are available for analysis. 



The REMOTS® sediment-profile and plan view photographic surveys were also 

 conducted to gather information on the area's sedimentary environment. This information 

 would determine if the BLDS was suitable to potentially receive dredged material from the 

 Boston Harbor Navigation Improvement Project and Berth Dredging Project. The 1991 

 side-scan sonar survey had mapped areas of circular or track-like dredged material patterns 

 at the site. The use of the area for dredged material disposal was consistent with its 

 characterization as depositional or nonerosive (Knebel 1993). By focusing on the areas of 

 dredged material disposal with the REMOTS® sediment-profile and plan view photographic 

 survey, the reconnaissance effort produced no evidence to preclude the future use of BLDS 

 for dredged material disposal. The major modal grain size was the silt/clay size class 

 (>4 phi) with very fine sands found in the surface sediments. Evidence of sediment 

 resuspension was limited primarily to winnowing of silts/clays from surface sediments. 



The assessment of BLDS was efficiently accomplished by basing the REMOTS® 

 sediment-profile and plan view photographic survey on the results of the previous side-scan 

 survey. The combined data sources provided a broad picture of the status of the historical 

 dredged material which has been at the disposal site for nearly 20 years. Based on the 

 1994 survey results, remediation is not necessary for BLDS, and the depositional 

 environment does not preclude its use as a disposal area. 



