Great Notch Reservoir Dam is a Class I, Large High Hazard Dam constructed across Yantecaw Brook. The dam is owned and maintained by the Passaic Valley Water Commission as a water supply reservoir. According to original design drawings, Great Notch Reservoir Dam was initially constructed in 1900. It is an earthfill dam with a concrete corewall, approximately 420 feet long and has a maximum height of 75 feet. The upstream and downstream slopes are constructed at 2 horizontal to 1 vertical, and covered with rock riprap. A concrete-capped masonry overflow spillway about 50 feet long is located on the left abutment. Two 48-inch diameter steel mains are constructed through the embankment to pump into the reservoir or release to the water supply distribution system.
In 2006 the dam was rehabilitated and FPA performed bidding and construction oversight services for the rehabilitation of the dam. Work consisted of construction of a concrete parapet across the dam, repair of four 4 foot diameter sluice gates and operators, installation of survey monuments, repair of the spillway, installation of bubbler system, removal of trees, concrete and other miscellaneous repairs.
FPA has performed a Regular Inspection of Great Notch Reservoir Dam in 2010, 2012, and 2016, and a Formal Inspection of the dam in 2011. All inspections were performed in accordance with the NJDEP Bureau of Dam Safety and Flood Control’s Guidelines for Inspection of Existing Dams. Additionally, FPA has updated the Inundation Mapping, Operation and Maintenance Manual and Emergency Action Plan for the dam.