BH designed a new 750,000-gallon, wire-wound pre-stressed concrete ground storage tank to meet peak hour demands and fire flow requirements and to satisfy a projected storage deficit. The tank is 54 feet in diameter and 45 feet high, with a base elevation of 880 feet and an overflow elevation of 925 feet.
Two types of tanks were evaluated for this project: welded steel and wire-wound pre-stressed concrete. A present-worth analysis to determine the life cycle costs for each type of tank indicated use of the wire-wound pre-stressed concrete tank over a 60-year life cycle would result in significant cost savings.
A WaterCAD hydraulic model provided by PAW was used to analyze the sizing and elevation of the tank. The results of the modeling indicated the tank at its specified elevation would be capable of providing adequate storage and pressures in the Prince Street Gradient at maximum daily demand conditions.
Approximately 5,200 feet of 12-inch diameter ductile iron pipe connects the tank to the distribution system at a point near the intersection of Comfort Road and Ridge Road.
A new below-grade precast concrete valve vault contains a conventional manual valve able to be electrically actuated from the Milton Filter Plant in emergency shutoff situations.A 100,000-gallon detention basin on the site contains emergency tank overflow and controlled tank drainage, and can accommodate the use of PAW’s portable dechlorination equipment, if necessary. The basin also captures stormwater runoff for release at a rate lower than the pre-development stormwater runoff. This discharge rate is also low enough for the runoff to be handled by downstream facilities.