United Water New Jersey (UWNJ) is a privately-owned water utility that provides
service to about 800,000 residents in 60 municipalities within Bergen and Hudson
Counties in Northern New Jersey. UWNJ owns and operates the water system which
includes water supply reservoirs, treatment facilities, storage and pumping facilities, and
transmission and distribution system piping. Water is supplied primarily from the
Haworth Water Treatment Plant (WTP) located in Haworth, New Jersey, which is a
direct filtration plant with pre-ozonation for disinfection and oxidation. The plant is
comprised of alum and polymer addition for coagulation, ozone for oxidation, followed
by flotation, direct filtration and ultimately chloramination for disinfection before
entering the distribution system.
The Oradell Reservoir serves as the source of supply for the Haworth Water Treatment
Plant. The quality of the water in the Oradell Reservoir has been deteriorating over the past 5 years. Runoff from surrounding developed areas and the introduction of
supplemental water from the Wanaque South project has led to extensive eutrophication
of the reservoir. The reservoir is also subject to periodic episodes of extremely poor
water quality. These conditions generally manifest themselves during dry periods in the
summer and in times of drought. It is these episodes that present a very significant
challenge to the treatment process. Consequently, UWNJ has pursued alternatives to
manage the Oradell Reservoir supply to enhance the raw water quality and to minimize
the challenges to the Haworth treatment processes. The following reservoir management options were identified and evaluated for the
Oradell Reservoir:
construction of a redundant intake structure in the Oradell Reservoir;
construction of a pipeline for direct transmission of Wanaque South water to the
Haworth Treatment Plant;
aluminum sulfate inactivation of phosphorus in the Wanaque South water prior to
discharge to the reservoir;
implementation of alternative algaecide/modified algaecide application
techniques;
construction of a curtain wall at the Wanaque South inlet to the reservoir; and,
installation of a reservoir aeration system.
Based on evaluations of these alternatives, a reservoir aeration system was recommended to stabilize raw water quality in the
Oradell Reservoir. More specifically, the system was designed to:
stabilize pH fluctuations;
maintain separation of the surface and bottom layers by thermal stratification to
facilitate depth-selective withdrawal, while managing the consequences of anoxia
in the deep layer;
reduce the release of nutrients, metals and organics from reservoir sediments; reduce the intensity of blue-green algal blooms by disrupting their habitation
patterns;
enhance competition within the algal community so as to favor beneficial
organisms (zooplankton) and non-nuisance algae (diatoms and green algae); and,
reduce reliance on algaecide applications for control of nuisance algae. Includes tables, figures.