AWWA WQTC62506

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.