The Massachusetts Bay Disposal Site (MBDS), a 2.0 nmi (3.7 km) diameter circular area centered at 42° 25.106' N, 70° 34.969' W (NAD 83), is located 12 nmi (22 km) southeast of Gales Point, MA. Water depths range from 269 to 302 ft (82 to 92 m). The MBDS was officially designated a dredged material disposal site by the U.S. Environmental Protection Agency in 1993. It was relocated from a partially overlapping interim disposal site, used for disposal from 1977 to 1993, known as the Foul Area Disposal Site or Boston Foul Ground. Of the three regional dredged material disposal sites off the coast of Massachusetts, MBDS is by far the most active, receiving material from such ports as Boston, Hingham, Salem, and Gloucester. Since 1982, approximately 12,693,865 yd3 of dredged material have been disposed at MBDS or the interim site. The possibility of disposing of relatively contaminated sediments at MBDS and isolating these sediments with a layer of clean cap material is currently being explored. A pilot project (Cohasset Harbor Capping Project) was conducted in 1998 to 2000 with clean sediment to determine whether capping is feasible at this deep water site. Extensive monitoring has indicated that the capping project was successful in isolating underlying sediment. - (DAMOS contribution no.147).