About 400,000 people live within a 10-mile radius of this 15-acre property in suburban Marlboro, N.J., that has had industrial tenants from as early as 1912. These include Champion Chemical Co., which in 1950 acquired the land and built an oil reclamation facility, and Imperial Oil Co., which leased the site from Champion in 1969 and operated an oil-blending complex with production, storage and maintenance buildings as well as 56 above-ground storage tanks on a portion of the property.
But in 1983, EPA added the site to its Superfund list due to the hazardous chemicals—including volatile organic compounds, pesticides, PCBs, lead, arsenic, metals and phthalates—found in site soil and groundwater. The contamination put surrounding residences and wetlands at risk.
As part of a long-term $41-million remediation plan, the project team worked to clean up the soil and groundwater.
"With the site being located in a residential area, Conti provided regular community coordination and public relations for our client as well," says The Conti Group, which submitted the project.
The scope of the project included the building of a 2,500-ft soil bentonite slurry wall, measuring up to 74 ft tall, around the site's perimeter. This was to ensure that none of the chemicals unearthed during excavation would seep out, Conti says.
The project team removed 220,000 tons of contaminated soil and debris, both hazardous and nonhazardous, which were treated and disposed of off site. A sampling program was also developed that included in-situ sampling for waste characterization and for determining the limits of contamination.
The team built a temporary 300-gallon-per-minute water treatment plant that cleaned more than 31 million gallons of water during the process. They also implemented a wetland remediation program that included wetland and stream restoration and grading.
The site was also backfilled with clean fill and landscaped, resulting in an area that today contains grasses, wetlands and a bike path.
Among the challenges for this project was an original design for a slurry wall that included many twists and turns that would be difficult to construct, as well as the planned location, which was close to an existing pond on the property, Conti says.
"After reviewing the specifics of the constructability of the slurry wall, we researched potential options that would allow for easier construction and cost savings," Conti says.
The end result was a redesign of the planned slurry wall, which shortened the wall by 300 ft and saved the client $2 million. The redesign also allowed the team to steer clear of nearby high-voltage towers and to minimize impacts on a local stream. As more material than expected was removed, the project's scope increased by 37%, but its budget grew by only 4%.
Emphasizing the stark contrast between the "before" and "after," Marlboro Mayor Jonathan Hornik was reported to have said that when he first visited Imperial with his father in 1983 at the age of 13, he felt that "if we walked on the premises we were going to start glowing, and I was nervous and scared." But the site today, he added, is a "really clean open space."
Imperial Oil/Champion Chemical Superfund Site, Marlboro, N.J.
Owner/Developer: U.S. EPA
Construction Manager: USACE Kansas City
General Contractor: The Conti Group
Government Designer: HDR
Slurry Wall Designer: Mueser Rutledge Consulting Engineers
Submitted by: The Conti Group