Reports
Poplar Island baseline study: sediment quality monitoring
1997, Hill, J.M., Park, J., and Panageotou, W.
File Reports, Coastal and Estuarine Geology, File Report 1997-03_Hill
Executive Summary
The proposed Poplar Island Restoration Project will be a new type of dredge material disposal site in the Chesapeake Bay. The facility will be constructed using a combination of low elevation upland disposal sites in conjunction with the formation of tidal wetlands. Potentially, this facility will establish new habitats for a wide range of aquatic and terrestrial wildlife. The configuration of the facility is designed to minimize environmental impact to the Bay. In order to assess the long term effects of the construction and operation of the facility baseline data on the sedimentary environment adjacent to the facility is required. The study presented in this report characterizes the physical and inorganic characteristics of the sedimentary environment at the site.
The Poplar Island site is located on the submerged platform on the eastern side of the main channel of the Bay. Currently it is a high energy wave swept environment characterized by sandy sediments. After construction of the facility the hydrodynamics of the area are expected to change to create an embayment which will be a sediment trap. The hydrodynamic connections of the facility will be into the embayment, thus any material discharged from the facility will concentrate in the embayment. It is expected that the sediment characteristics will change from a sandy environment to a finer grain sediment type, with an accompanying change in metal concentrations. In order to characterize grain size induced variability of the trace element concentrations, 60 samples within the same geochemical environment in the Bay were collected spanning the entire range of sediment composition . These samples were used to establish the regional baseline behavior of the trace metals.
In the area around the proposed Poplar Island facility samples from 27 sites were collected. Eleven of the sites correspond to water quality and benthic sampling stations. The other stations were collected to obtain more detailed sediment characterization of the area. Samples were primarily located in the area of the future embayment. One set of preconstruction samples adjacent to the proposed facility were collected in October 1995 for sediment characterization, including the stations that correspond to water quality sampling locations. Samples for the regional baseline levels and for baseline data to correspond to water quality and benthic sampling were collected in July 1996. The results of the sample analyses show that the area is a sandy environment with elemental concentrations of carbon, nitrogen, sulfur, and trace metals typical for the region of the Bay in which it is located in.
