On August 28, 1997 researchers led by Bob Chen from the University of Massachusetts Boston collected surface sediment samples (See Table 1 and Figure 1) from disposal cell one and surrounding areas of the Conley Terminal dredging project in order to follow up on the initial August 13, 1997 sampling trip and to provide information to help with plans for future cell sampling. In addition, the researchers collected bathymetric data along a North-South transect down the center of the disposal cell using the R/V Neritic (See Table 2 and Figure 2). The bathymetric data showed a flat region in the southern portion of the cell. An abrupt change in depth occurred approximately 200 feet from the southern cell boundary. North of this abrupt change in topography, water depth was shallower and the bottom was uneven. Two sediment samples collected in the deeper flat region of the southern portion of the cell were composed of very black, fluid, fine-grained material. A sample collected in the northern uneven region was composed of sand with 3 mud balls. A sample collected at the boundary between these regions was composed of a mixture of black mud and sand. In addition to these samples, sediment samples were collected from an area adjacent to the disposal cell, from Reserve Channel, from the Mystic River, from Fort Point Channel, and from other regions. These samples will be examined for potential markers for the dredged material.

Table 1. Sampling Locations

Table 2. Bathymetry Data

Although only one transect was made, the bathymetric data suggest that the flat region in the southern portion of the cell represents fine-grained material. The uneven region in the northern portion of the disposal cell appears to be the sand cap. Although nothing is known about the East -West extent of the southern fine-grained region, if the data from the transect down the center of the cell are representative, then approximately 30 percent of the cell surface is composed of fine-grained material. Because the results of the August 13 sampling trip indicated that this fine-grained material is several feet thick in at least some locations, this material may represent the material dredged from Reserve Channel. The northern 70 percent of the cell appears to be covered by sand.

Figure 1. Sampling Locations

Click on figure for larger (and better quality) figure.

Figure 2. Bathymetry Section