Poplar Island Environmental Restoration Project: Dike Construction and Wetland Development
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Donegan
Abstract: Poplar Island is a 1,140-acre environmental restoration project located in Chesapeake Bay approximately 35 miles southeast of Baltimore in Talbot County, MD. The restoration of Poplar Island (to the approximate 1847 footprint) using dredged material was conceived by Maryland Port Administration (MPA) in cooperation with the U.S. Army Corps of Engineers, Baltimore District (CENAB), Maryland Environmental Service (MES), state agencies, federal agencies and local governments, citizens and private interest groups. The project is a beneficial-use site, using dredged material to create both uplands and intertidal wetlands with a focus on habitat diversity. Poplar Island will provide a total capacity of approximately 42 million cubic yards of dredged material. Creating the initial containment dike system (42,000 ft of perimeter dikes and 23,000 ft of interior dikes), involved the following construction elements: exterior stone toe dike, sand core, slope underlayer and slope armor stone. The sand core material (approximately 6 mcy) was excavated from sub aqueous borrow areas on site. Approximately 850,000 tons of stone was mined and transported to the project. Because of funding and schedule limitations, the project was designed for construction in two phases. Phase I (640ac) is the northern portion of the site and contains four remnant islands. Phase II (500ac) is the southern portion of the site. Wetland creation (570ac) is a top priority with several challenging engineering issues, including: construction and maintenance of diverse habitat features (high/low marsh, bird islands, ponds and tidal flats); optimization of dredged material dewatering/consolidation to achieve final target elevations; channel design and construction to achieve proper tidal flushing; evaluation and field-testing of planting/seeding methodologies, and design and implementation of effective monitoring to measure success. This paper will address the engineering issues associated with initial construction of the containment dikes, filling of the island, and development of the wetland cells.
Keywords: Consolidation, habitat, armor stone, stockpile, sand cor