In 2013, Money magazine rated the Union County township of Berkeley Heights as the 6th best place to live in the country. With a population of 13,000, Berkeley Heights offers a 50-minute commute to New York City and access to the Watchung Reservation for boating, picnics, and horseback riding.
Berkeley Heights is served by a 3.1 million gallon per day (MGD) advanced secondary wastewater treatment plant. The plant was designed by Killam Associates, which was acquired by Mott MacDonald in 2001.
The plant discharges directly to the Passaic River, and because the river rapidly dilutes the effluent, it has a relatively lenient permit limit for nitrate. However, new permit limits set by the New Jersey Department of Environmental Protection (NJDEP) made it necessary to modify the nitrification aeration tanks to provide for partial denitrification.
In 2007, the township engaged Mott MacDonald to design the required modifications. We used a BiowinTM software modeling for wastewater treatment to confirm the optimum dimensions for dividing the aeration tanks with concrete baffle walls into anoxic and oxic zones.
The anoxic zone promotes the removals of nitrates by using raw sewage ( with a new gravity flow partial bypass around the secondary treatment system) as the carbon source for denitrification. Mott MacDonald specified highly efficient new-generation hyperbolic mixers to achieve mixing requirements.
A supervisory control and data acquisition (SCADA) system was implemented to control the denitrification process.
The improvement to the denitrification system at the wastewater plant in Berkeley Heights has enabled the township to meet the effluent permit requirements imposed by the NJDEP.
Funding for denitrification and other improvements to the plant were partially funded by a low-interest loan obtained by Mott MacDonald from the New Jersey Environmental Infrastructure Financing Program.