On August 2, 1973, heavy rain overflowed the banks of the Green Brook, a tributary of the Raritan River in central New Jersey. The flooding killed six people and turned streets into rivers, submerging cars and filling basements with water. When the floodwaters receded, they revealed millions of dollars’ worth of damage to homes, businesses, and infrastructure.
To help protect communities from future flooding, the U.S. Army Corps of Engineers, New York District recommended a flood risk management project for the Green Brook sub-basin. In 1986, Congress authorized the Green Brook project for construction, and after several studies, construction began in 1999.
The Green Brook project area covers 68 square miles, 13 municipalities and three counties in central New Jersey. Due to its size, the project is split into three sections: the Upper Basin, Stony Brook, and Lower Basin. Each section is further divided into construction segments.
Before starting work on a project segment, the Corps must first perform surveys and design project features. The project management team must confirm there is no environmental contamination, take soil borings to determine if heavy levees and floodwalls can be supported, and complete wetland delineations to mitigate or avoid environmental impacts. In addition, the project sponsor, the New Jersey Department of Environmental Protection (NJDEP) must obtain environmental permits and real estate for the project. Altogether, this process can take years.
The Green Brook project uses a system of levees, floodwalls, pump stations and road closure gates to keep communities in New Jersey safe and dry. This system protects the boroughs of Bound Brook, Middlesex, Dunellen, and North Plainfield, as well as the township of Green Brook.
In the Stony Brook and Lower Basin project sections, construction has been completed in the borough of Bound Brook and is ongoing in the borough of Middlesex. Project work consists of levees and floodwalls along the Green Brook and its tributaries.
To build a levee, the contractor creates a long earthen mound out of a water-impervious material like clay and covers it with grassy earth. This structure helps contain the river when a storm event causes flooding. To build a floodwall, the contractor anchors tall, concrete-and-steel columns deep into the bedrock below the ground, then fills the spaces between those columns with concrete to form a solid barrier. While floodwalls are typically more expensive than levees, their smaller size means they are used more often in urban areas with space constraints.
Work on the Stony Brook and Lower Basin sections is scheduled to be completed by approximately 2030. The Corps is currently studying the Upper Basin section to determine if a flood risk management project is feasible.
“Without the Green Brook flood risk management project, major storms would continue to inflict significant flood damages on local communities,” says Alek Petersen, project manager. “This project will help protect area residents from the devastating effects of recurrent flooding.”
The project’s flood control features in the borough of Bound Brook have already helped area residents escape major damages. Without protection, flooding would have destroyed much of the borough during Hurricane Irene in 2011 and Hurricane Ida in 2021.
The Stony Brook and Lower Basin project sections cost approximately $870 million. The two sections are 75 percent federally funded and 25 percent non-federally funded by NJDEP. As the project sponsor, NJDEP also provides land, easements, rights-of-way, and relocations for the project, and will assume the costs of operation and maintenance once construction is completed.
In fiscal year 2022, Congress passed the Disaster Relief Supplemental Appropriations Act, which allocated $496 million for the Stony Brook and Lower Basin project sections. This funding will allow the Corps to begin awarding larger construction contracts to maximize cost efficiency and expedite construction.
Upcoming Construction Contracts
In August 2022, the Corps will issue a contract to repair minor damages caused by Hurricane Ida to the borough of Bound Brook’s flood risk management features. In September 2022, the Corps will award a contract for Segment C2&H in Middlesex borough. The Corps will award additional contracts for Segments C3 in 2023 and C4 in 2024. Project work will consist of constructing levees, floodwalls, road closure gates and pump stations.
“This project has been decades in the making,” says Petersen. “The New York District, in cooperation with project partners, is pleased to help improve public health and safety by protecting vulnerable communities from flooding.”