The West Milford Township Municipal Utilities Authority (MUA) received $1.06 million from the New Jersey Environmental Infrastructure Financing Program to replace antiquated sewers. The project, now under construction, will correct a significant infiltration and inflow (I/I) problem in the Awosting section of the Township.

The 105-acre Awosting Community, located at the southeastern end of Greenwood Lake next to the Wanaque River, is nearly entirely developed, with virtually all of its 615 residents serviced by centralized sewers. The existing sewerage system consists mostly of 8-inch diameter vitrified clay pipe - 70 to 80 years old. The manholes are mainly brick formed, and most service laterals are vitrified clay pipe of comparable age to the collection system. Clay pipe and brick manholes have many joints that leak over time, causing extraneous water to enter the sewer system.

The limited expanse of the stormwater collection and drainage systems in the community is also thought to contribute to the I/I problem. The majority of the sewer lines being replaced are located on private property between existing homes and Greenwood Lake.

The Awosting Sewage Treatment Plant (STP) is permitted for an average daily flow of 45,000 gallons per day (GPD) but peak I/I conditions can result in total system flows in excess of 1,000,000 GPD. The excessive influent volume inhibits the plant's ability to adequately process and treat the generated wastewater flows. This has caused wet weather overflows near the plant and discharges of untreated wastewater into the Wanaque River. To mitigate this situation, the MUA installed a temporary Wet Weather Overflow Treatment System to provide screening, disinfection, and dechlorination of overflows. This facility will remain in operation until the permanent corrective measures are completed.

The proposed project, which will replace the lower reaches of the Awosting collection system, consists of approximately 4,000 linear feet of 8-inch gravity sewer main, 375 feet of 2-inch low-pressure force main, and the replacement of 56 house laterals. Approximately twenty homes require grinder pumps because their elevations are lower than the replacement sewer main. The new alignment moves the majority of the sewer lines off private property and into existing roadways. The design also allows the continued conveyance of flows from the upper reaches of the collection system by gravity to the STP. In March 2000, the MUA and Department executed an Administrative Consent Order to complete Phase 1 of the project on or before October 16, 2002.

The existing sewer mains and manholes will be abandoned in place upon completion of the new sewer main and house connections. The manhole inverts will be sealed with concrete and the top sections will be partially collapsed and then backfilled to grade. Portions of the sanitary sewer, which are located directly below existing house foundations, will be grouted with a concrete slurry mix.

For additional information concerning this project, please contact Paul Hauch, Bureau of Engineering North at (609) 292-6894 or at Paul.Hauch@dep.state.nj.us.