The International Trade and Logistics Center (iPort 12) is a state-of-the-art warehouse facility located on 70 acres of the former Carteret municipal solid waste landfill. Development of the landfill site was a joint venture of New York-based P/A Associates and Panattoni Development Company, headquartered in Edison, New Jersey. Moretrench worked closely with Panattonis construction arm and SESI Consulting Engineers, design and oversight engineer for environmental compliance and development of the property, in the design/build of the landfill gas and leachate system integral to landfill closure.
The two warehouses that comprise iPort12 have a total footprint area of 1.25 million square feet. The remediation system consisted of:
- A gas extraction and permanent flare system installed beneath the two buildings and around the perimeter of the site to control and mitigate methane emissions across the entire 70 acres.
- A perimeter hydraulic barrier trench to collect and contain the leachate for pumping to an on-site treatment facility.
Moretrenchs scope of work also included provision, installation and operation of a temporary landfill gas flaring system as part of a pilot test conducted to determine the appropriate size and design of the permanent flare.
Methane Gas Recovery
Forty five vertical extraction wells were installed for the project, together will more than 100,000 feet of buried HDPE collection and conveyance pipe ranging in diameter from 1.5 to 16 inches. For well installation, bucket auger drilling techniques were used to advance 24-inch diameter boreholes through the uncapped landfill to a depth of 20 feet below working grade. Six-inch diameter wellscreen and casing was placed to full depth and the borehole annulus around the wellscreen was filled with stone backfill. A bentonite plug and clean fill was then placed to seal the well from the environment. The installed well was connected to the header system via an instrumented well head enclosed within a subsurface vault. The system also included condensate drains and sumps, cleanouts, monitoring vaults, and slotted horizontal collectors installed beneath the building floor slabs to capture any remaining free gases. Total system flow was rated at 2,000 scfm. Collected gas was processed through a permanent vacuum blower and flaring system furnished and installed by Moretrench.
During construction, Moretrench installed a temporary sump dewatering system along the alignment of the perimeter leachate collection trench to draw the static groundwater table down below design invert elevation for safe trench box excavation. Approximately 6,000 linear feet of slotted HDPE pipe was placed in the trench at elevation 0-ft mean sea level within a permeable gravel bedding medium to collect the leachate and pump it via a force main to an on-site treatment plant. The pumping system consisted of 14, evenly spaced collection sumps, each fitted with pneumatic pumps and controls. Some 8,000 linear feet of 1.5-inch and 3-inch HDPE pipe was laid above the collection system for the compressed air supply and leachate force main respectively.
The on-site treatment system, furnished and installed by Moretrench subsidiary Ground/Water Treatment & Technology, consisted of settling tanks, transfer pumps, a main control panel and associated piping and instrumentation. An air compressor system was included to provide the compressed air for driving the pneumatic pumps. The controls of the air compressor system were integrated with the treatment system to stop flow in the event of a system fault. Treated water was discharged to the Carteret sanitary sewer system.