Proactive Force Main Management at Toho Water Authority

How does a major wastewater utility brace itself for certain future environmental, social, and economic disruption? On what foundation must the knowledge of its buried infrastructure be built? What tools and information must it be armed with to minimize impact and maximize relief? In a state that experiences extreme weather events, population surges, and budgetary spending stresses, these are questions Toho Water Authority (Toho) routinely asks itself. Implementing a risk-based approach to condition assessment of its force mains, Toho has maximized its resources and optimized its operational resilience through data driven decisions. Established in October 2003 by a special act of the Florida legislature, Toho is the largest provider of water, wastewater, and reclaimed water services in Osceola County. Toho currently serves over 100,000 customers in Kissimmee, Poinciana, and unincorporated areas of Osceola County. Toho owns and operates 13 water plants and 8 wastewater plants. With a 300+ person workforce, Toho treats and distributes approximately 37.5 million gallons of potable water and reclaims 27 million gallons of wastewater each day. Toho is governed by a five-member board of supervisors responsible for approving all its operating policies and its $124M operating budget. Toho was established for the sole purpose of providing regional stewardship over water resources in Osceola County. Wastewater is collected by the gravity sewer system consisting of 921 mi of mains and 23,166 manholes and is gravity fed to one of 423 lift stations owned and maintained by Toho. Wastewater is then conveyed through 323 mi of force mains to either a downstream lift station area or one of the eight (8) water reclamation facilities. Toho’s eight (8) water reclamation facilities operate independently in specific geographic areas. Historic assumptions associated with force mains are proving to be less reliable based on advancements in condition assessment. Historically, a desktop study would identify known high points, utility crossings, and soil conditions as a basis for pipeline management decisions. This paper presents a condition assessment and risk management case study of 15 critical ductile iron pipe (DIP) and cast iron pipe (CIP) force mains, ranging in diameter from eight (8) to 30 in., and totaling approximately 30 linear miles.