In 2006, engineers reused 250,000 cubic yards of dredged sand to restore Elders Point East in Jamaica Bay. 10 years later, the approach had restored 40 acres of wetlands and helped reverse marsh-island erosion

A project in Jamaica Bay demonstrated how material removed from a significant shipping channel could be redirected toward environmental restoration. Beginning in 2006, the U.S. Army Corps of Engineers (USACE) used dredged sand from the New York Harbor deepening project to rebuild the eroding Elders Point East marsh island.

The work was part of a broader change in how dredged material was handled. Instead of treating sediment only as material requiring disposal, USACE developed approaches for putting suitable dredged material to beneficial use. In Jamaica Bay, that approach helped restore wetlands while supporting the expansion of navigation infrastructure in New York Harbor.

Research behind the approach

The shift started with federal attempts to better understand the environmental and engineering challenges connected with dredged material.


The 1970 Rivers and Harbors Act authorized USACE to study techniques and procedures for dredged-material disposal. At the time, around 400 million cubic yards of material were being dredged each year.

USACE launched the Dredged Material Research Program (DMRP) in 1973. Led by the USACE Waterways Experiment Station, the program lasted five years and cost almost $33 million.

The DMRP found that greater oversight was required when selecting locations and methods for placing dredged material. Its work also analyzed beneficial uses for the material and recommended improved methods for constructing and managing confined disposal areas.

After the DMRP ended, USACE continued researching the environmental impacts of dredged-material placement. The Clean Water Act of 1972 had established a requirement that disposal of dredged material have minimal environmental impacts.

This research eventually influenced the New York District's approach to managing sediment generated by harbor improvements.

New York Harbor deepening

By the 1980s, authorities were concerned about potential sediment disturbance connected with future dredging in New York Harbor. Sludge from New York City's water treatment plants had accumulated off the southwestern coast of Long Island, and some of that material would have to be dredged if the harbor channel were deepened.

Congress authorized USACE in 1996 to conduct a comprehensive navigation study and assess whether the harbor could be deepened to at least 50 feet to accommodate larger commercial ships.

The Corps concluded that nine navigation channels entering New York Harbor should be deepened. Because the work would have environmental impacts, USACE proposed mitigation measures that included using dredged material to develop 7.5 acres of shoreline habitat and restore 11 acres of tidal wetlands.

Jamaica Bay becomes the restoration site

Once the project was authorized, the New York District began deepening the nine channels. However, the planned littoral habitat mitigation project at Old Place Creek on Staten Island had to be reconsidered.

The New York State Department of Environmental Conservation asked USACE to halt the project because development was planned in the area.

New York State recommended Jamaica Bay in Queens as an alternative. The U.S. Fish and Wildlife Service had designated the bay as habitat requiring special protection under the New York-New Jersey Harbor Estuary Program. At the same time, marsh islands in Jamaica Bay were experiencing severe erosion.

USACE selected Elders Point East Island for the restoration effort. Between 2006 and 2007, engineers placed 250,000 cubic yards of dredged sand from the harbor-deepening project on the island. The work restored 40 acres of wetlands.

The project offered a practical example of how dredged material generated by navigation improvements could be used to rebuild deteriorating coastal habitat.

Restoration spreads across four islands

The work did not end at Elders Point East.

Between 2009 and 2012, USACE worked with the Port Authority of NY/NJ, New York City Department of Environmental Protection, New York State Department of Environmental Conservation and the National Park Service to restore another 117 acres across four marsh islands in Jamaica Bay.

The restoration used 924,000 cubic yards of dredged sand.

The Corps carried out work at Elders Point West Island and Yellow Bar Hassock Island under Section 207 of the Continuing Authorities Program, using dredged material generated by the harbor-deepening project.

After the islands were graded to the appropriate elevations, hundreds of thousands of plants and hundreds of pounds of seeds were planted at Elders Point West and Yellow Bar.

Dredged sand was also positioned at Black Wall and Rulers Bar islands. A community-based planting effort restored 30 acres there in 2013.

USACE continued monitoring the mitigation and restoration projects while the remaining harbor-deepening work was carried out.

By 2016, USACE had completed the harbor deepening to 50 feet, at a total cost of $2.1 billion.

Supporting a major commercial gateway

The restoration projects were carried out alongside improvements to one of the country's most important maritime facilities.

The Port of New York and New Jersey is described as the nation's premier gateway to the world, supporting global commerce and generating jobs and economic activity. It is the largest port in the United States and one of the world's most productive high-volume port operations.

The port system includes the existing 50-foot navigation channels and surrounding terminals and facilities. In 2015, the port handled approximately 6.4 million twenty-foot equivalent units.

Its connections to rail, road and inland waterways give around 23 million local consumers and as many as 100 million other customers access within 36 hours.

Six container terminals receive vessels operated by major ocean carriers serving almost every region of the world.

Before the Harbor Deepening Project and the subsequent Harbor Deepening and Channel Improvements (HDCI) study, the harbor's channels did not provide sufficient access for large post-Panamax ships, which have drafts of 48 feet or more.

The HDCI Feasibility Study determined that navigation could be further improved by deepening the channels by another 5 feet, to 55 feet, with the potential to enhance the region's economy.

Source: U.S. Army Corps of Engineers

FAQs:

Q1. What is dredged material?

Dredged material is sediment removed from the bottom of waterways, rivers, channels and harbors. It can sometimes be reused for environmental restoration when appropriately managed.

Q2. Why is dredging necessary?

Dredging helps maintain navigation channels at depths needed by commercial and other vessels. It can allow larger ships to reach ports and support maritime transportation.