After the installation of underground filtration systems, a landfill was converted to office space
A former contaminated landfill in the New Jersey Meadowlands was able to become a viable commercial office complex due to remediation efforts and two large, on-site underground filtration systems that can trap and store nearly 30,000 lb of sediment.
During the 1970s and the early 1980s, the 6-acre site was one of many major landfills in New Jersey. An $8 million remediation project saw the area capped to control gas emissions and protect the surrounding area from the contaminated soil, plus reduce the amount of leachate and also capture storm water runoff.
According to the New Jersey Department of Environmental Protection (NJDEP), hazardous organic and inorganic compounds were detected in the shallow groundwater, which would discharge into the adjacent wetlands and surface water. Volatile organic compounds, polyaromatic hydrocarbons (PAHs), pesticides and metals were detected at the site along with medical waste, chemical drums and tanks. Because the landfill was originally constructed without a bottom liner, leachate was free to drain out of the waste materials and directly into the groundwater. NJDEP estimated that up to 83,000 gallons per day of that leachate flowed into the Passaic River.
The NJDEP regulation requires runoff from any new impervious surface be treated to remove 80% of total suspended solids (TSS), which was the reason for the large filtration system. The 6-acre remediated site was designed to have two warehouse-size buildings, the largest being nearly 200,000 square feet, along with new parking lots.
According to the calculations required by NJDEP, the maximum treatment flow rate was to be 10.9 cubic feet per second (cfs) and that each acre would generate 600 lb of sediment a year. In order to be in compliance with the NJDEP regulations, an underground system measuring nearly 2,000 square feet would be required. There was not space, however, for one system that would provide the required capacity. This was due to the site's close proximity to the Passaic River, a road and the size of the buildings that would be constructed.
Also, much of the area is unusable land with hills and slopes created when it was an operating landfill. The design engineering firm, Paulus Sotolowski & Sartor LLC, decided to use two filtration units with a total of 109 BayFilter 545 cartridges, each of which can treat 0.1 cfs and can store 262 lb of sediment. There would be 55 cartridges in one unit and 54 in the other. This filtration device from Advanced Drainage Systems Inc. (ADS) is designed to remove fine sediments, heavy metals and phosphorus with its spiral wound media filter cartridge. The storage capacity of the entire filtration system is 28,558 lb of sediment. ADS engineers showed the site could generate 3,606 lb of sediment per year, which would set the maintenance timetable at almost every eight years.
Aside from being able to fit the available space, the two concrete vaults holding the cartridges were assembled on-site using six precast concrete parts. The interior dimensions of each vault are 10 feet wide by 42 feet long by 6 feet high. BayFilter worked with the pre-caster to have the concrete vaults designed in pieces that could be picked up and installed using an excavator so the contractor — DS Meyers Enterprises LLC — would not have to add a crane to the heavy equipment list. This method, instead of using a “box culvert," enabled the cartridges, outlet manifolds and other internal components to be installed without the need for an OSHA confined space permit.
Water is conveyed to the filtration units from manholes on the site through an 18-inch diameter inlet pipe. The layout of the filters inside the vaults enables the water to be evenly distributed to the filter cartridges. Inside each vault is a trolley used to remove and replace the filter cartridges that are 22.5 inch high, have a 30-inch diameter and weigh 250 lb. During a storm, runoff begins to fill the structure. When the water surface elevation in the vault reaches the operating level, water flows through the BayFilter driven by a hydrostatic head. Within the filter, the water flows through a proprietary filter media and drains into a vertical pipe. The vertical drain is connected to the underdrain system which conveys filtered water to the outfall.
After the filtration units were installed, the vaults were topped with a separate slab and several feet of cover.
The completed site redeveloped by Hartz Mountain Industries is now home to a new 57,000 square foot Cummins Power Systems facility and a specialized 200,000 square foot storage facility for one of the largest refrigerated warehousing companies.