News and information for the worldwide dredging industry

Bookmark and Share Email this page Email Print this page Print

Poplar Island Reaching Capacity; Expansion Authorized by WRRDA 2014

Aerial view of Poplar Island, oriented with north on the left, shows the location of upland Cells 2 and 6 along the west side of the island, and the wetland cells ranged along the east side of the island. Notes explain the status of each wetland cell as of December, 2014, incorporating planning for the expansion of the island by raising the dikes, and creating more area north of the island. Other photos show details of the unloading and filling operations.

Aerial view of Poplar Island, oriented with north on the left, shows the location of upland Cells 2 and 6 along the west side of the island, and the wetland cells ranged along the east side of the island. Notes explain the status of each wetland cell as of December, 2014, incorporating planning for the expansion of the island by raising the dikes, and creating more area north of the island. Other photos show details of the unloading and filling operations.

Poplar Island, approximately 15 miles south of the Chesapeake Bay Bridge, is an environmental restoration project and placement site for maintenance material from the Chesapeake Bay navigation channels in Maryland. Its official name is the Paul S. Sarbanes Ecosystem Restoration Project.

Once home to almost one hundred people, a lumber operation and farms, Poplar Island all but disappeared by 1990 due to the erosion of its shorelines by wind and wave action from the Bay. In 1994, the state of Maryland and the U.S. Army Corps of Engineers (USACE) agreed to restore the island to its approximate 1,847 footprint, to provide capacity for dredged material and vital but disappearing island habitat for Chesapeake Bay fish and wildlife.

USACE and the Maryland Port Administration (MPA) entered into a state and federal partnership to restore Poplar Island. The study and design effort began in 1994, with key design consultants including Gahagan & Bryant Associates, Inc. and Moffatt & Nichol Engineers, among others. Hydrographic surveys and geotechnical studies provided the data needed for dike design, and nearby natural wetlands were studied to develop design parameters for construction of the island’s future wetlands habitat. The design effort included coastal, dredging and environmental engineering, culminating with the completion of construction plans, specifications, and cost estimates for the environmental restoration project.

December 11, 2014. Norfolk Dredging Company’s barge unloader, moored at the unloading station at the south end of Cell 6, removes material dredged from the Craighill Channel Angle.

The environmental and cultural resource studies also provided the data needed to write the Environmental Impact Statement (EIS), in compliance with National Environmental Policy Act (NEPA) guidelines. Public hearings and review of the environmental and cultural assessment reports provided the input necessary to r each consensus on a final design and layout of the selected plan. The result is a project that beneficially uses dredged material from navigation channels of the Chesapeake Bay to create a combination of wetlands and upland island habitat. The agreement for construction of the project was executed in April 1997.

Norfolk Dredging Company’s discharge pipe at the southwest corner of upland Cell 2.

BUILDING THE DIKES

The Phase I contract for the island’s northern 640 acres was awarded to Kiewit Construction, Inc. in January 1998. Kiewit subcontracted Great Lakes Dredge and Dock Company for hydraulic dredging and stockpiling sand to build the dikes to an elevation of approximately eight feet above mean lower low water (MLLW). Approximately 3.2 million cubic yards (mcy) of sand was placed by dump truck along the 38,000-foot perimeter and interior dikes. The sand came from borrow areas within the constructed island’s footprint. The dikes for Phase I were completed in 2000 at a cost of $54.8 million. The first inflow of dredged material followed in 2001, as maintenance material from the Port of Baltimore channels was placed in Poplar Island.

Frank Hamons, deputy director for Harbor Development at MPA for more than 30 years, and now a senior associate with GBA, was impressed with the success of the project from the beginning.

A view of upland Cell 2 facing north, taken from the intermediate cross dike that spans the cell from west to east.

“We knew that the wildlife habitat was going to be successful because the birds were nesting on the island before we even finished constructing the dikes. What a wonderful opportunity, helping to secure the future of the Port of Baltimore and Chesapeake Bay wildlife with one very beneficial use project,” Hamons said.

The Phase II contract for the island’s southern 500 acres was awarded to Tidewater Construction Corp. in April 2000. The contract involved placing approximately 1.9 mcy of sand along the 24,000-foot perimeter and interior dikes. Construction was completed in February of 2002 at a cost of $41.4 million.

Norfolk Dredging Company’s discharge pipe at the northwest corner of upland Cell 6, facing south.

The 1,140-acre island is divided into large upland and smaller wetland cells. Twelve wetland cells run along the eastern side of the island, providing diverse habitat features such as high and low marsh, bird nesting islands, ponds and tidal flats. The project is used by a diverse array of fish and wildlife including; muskrat, rockfish, terrapins, various waterfowl species and other migratory birds such as ospreys, terns, cormorants, and spotted owls. Bald eagles nest on nearby Jefferson Island and use Poplar Island for hunting and fishing. The U.S. Fish and Wildlife Service (USFWS), National Oceanic and Atmospheric Administration (NOAA), United States Geologic Survey (USGS), University of Maryland Center for Environmental Science (UMCES), and Ohio University are on-site to monitor the success of the restoration effort through the success of targeted species utilizing the habitat.

GLDD’s Barge Unloader working at Poplar Island.

The two upland cells run along the western side of the island, with dikes at an elevation of approximately 22 to 25 feet above MLLW. The upland cells provide the bulk of dredged material placement capacity on the island. USACE and MPA needed to maximize capacity in order to ensure that placement needs were met for maintenance dredging of the Bay channels for at least 20 years. With an annual placement requirement of approximately two mcy, a total site capacity of 40 mcy was needed. The upland cells will also provide wildlife habitat (in the form of forested and open areas), to be developed sometime after the final placement of dredged material.

The dredged material placed at Poplar Island comes from the Maryland Bay channels, chiefly the Craighill, Brewerton Extension, Tolchester and Swan Point channels at the Port of Baltimore. These channels together have an annual maintenance requirement of approximately two mcy. In addition, material from the C&D Canal southern approach channel has also been placed at Poplar, putting even more demand upon the remaining capacity. Typically, the channels are dredged mechanically, and the material is placed into scows and transported to Poplar, where the material is offloaded into the cells by a hydraulic unloader.

The eastern end of the Cell 2 cross dike, showing the inlet that allows slurry to pass through toward Spillway 1.

The Maryland Environmental Service (MES) operates and maintains Poplar Island; this includes water quality and wildlife monitoring, construction, crust management, engineering, outreach and regulatory agency coordination. Crust management facilitates the consolidation process and helps to achieve the planned capacity. The Poplar Island management team is made up of the USACE, MPA and MES.

The first inflow of dredged material into Poplar Island in the spring of 2001 totaled approximately 7.0 mcy. Since then there have been 10 more inflows with a total of about 24.3 mcy being placed over a 12-year span. An additional three mcy is anticipated for placement in the upcoming 2014/2015 dredging season. This will put the remaining capacity of Poplar Island somewhere between 12 and 13 mcy.

Including the C&D increases the annual placement capacity requirement to 3.2 mcy. At this rate of inflow, the Poplar Island site will likely be full in the next five years. Additional capacity is needed to avoid a shortfall and to ensure that the navigation channels continue to be maintained. For this reason, USACE and MPA have planned for an expansion of Poplar Island, which is now in the design phase.

Spillway 1, a T-weir, at the north end of upland Cell 2.

WRRDA AUTHORIZED EXPANSION

Known as Phase III, the expansion was reauthorized in Water Resources Reform and  Dev elopment Act (WRRDA) on June 10, 2014. It will be both a vertical expansion (raising existing upland dikes) and a lateral expansion adjacent to and northeast of the existing island. Construction of the vertical expansion, slated to start in 2016, includes raising the existing dikes in the two upland cells by five feet. This is expected to provide an additional five to six mcy of capacity. Approximately 0.5 mcy of sand borrow will be required to raise cell 2 and 6 dikes from elevation +25 to +30 MLLW. When filled, the upland cells will be developed using vegetation appropriate for upland habitat.

The vertical expansion is planned to be built with sand from a borrow area just southwest of the existing project, and the lateral expansion from a borrow area within the expansion area footprint. It will require 3.1 mcy of sand borrow to construct the dikes for both the upland and wetland cells.

The lateral expansion will be constructed between two natural oyster bars to the east and west of the footprint. Specific time of year restrictions on mechanical and hydraulic dredging will be enforced to prevent any negative impacts to these oyster bars.

Work on the lateral expansion is expected to start sometime between 2017 and 2018 and will include the construction of a 110-acre open water embayment habitat, 206 acres of wetland habitat and 259 acres of upland area. The wetland and upland areas are expected to provide an additional five mcy and 19.5 mcy of capacity, respectively, for a total of 24.5 mcy of capacity.

Dredged material placement is expected to start in the wetland cells of the expansion in 2019 and in the upland cell in 2021. Placement is expected to continue until approximately 2029. A potential successor to the Poplar Island Environmental Restoration Project, the Mid-Chesapeake Bay Island project, was authorized in WRRDA 2014.

The Poplar Island restoration project has been a big success in providing both wildlife habitat and beneficial use of dredged material. The restoration project has succeeded in attracting diverse wildlife to the island habitat, which is being continually studied to ensure that the ecosystems are successful.

“Innovative equipment is being used on this project. Hover craft, low ground pressure vehicles, specialized sampling, and discrete sampling devices with vacuum assist for accessing the cells and sampling and monitoring the placed material, make Poplar Island a model for future environmental restoration projects,” Dennis Urso, GBA vice president, said.

This project has attracted attention both in the U.S. and across the globe. In 2014, visitors, including port managers and those responsible for dredged material management, have come from throughout the U.S., and from Algeria, Colombia, Democratic Republic of Congo, Ethiopia, Germany, Ghana, Guinea, Haiti, Indonesia, Iraq, Iraq, Jordan, Kenya, Liberia, Nepal, Netherlands, Nigeria, Palestinian Territories, People’s Republic of China, Philippines, Sierra Leone, South Africa, Thailand, Tunisia, Vietnam, and Yemen. The visitors learned about the success of this beneficial use project and how facets of the project could be employed in their own present and future projects, according to Justin Callahan, COE project manager.

Constrained budgets for civil works construction could make funding the Poplar Island Expansion project challenging. There will need to be some flexibility in the sequence of construction in order to get the project moving. All of the stakeholders are up to the challenge and ready to launch a successful expansion of the Poplar Island restoration project. The next challenge will be preparing for the Mid-Chesapeake Bay Island restoration project, which will need to be ready by 2030.

Add your comment:
Edit Module