Financial outlay modeling for a local sewer rehabilitation strategy

Modern infrastructure systems are highly developed, with considerable capital funding invested in them. While capital is spent on new infrastructure initiatives, the maintenance of the present infrastructure must not be neglected. Increasingly, public agencies are being urged to develop improved systematic methodology for allotting their period budgets more appropriately so that the capacity of the installed infrastructure is more fully utilized and sustained. When planning the allocation of investment funds, multiple objectives may exist that are dependent on the constraints, resources available for construction, and the interrelationships and dependencies among all of the alternatives. This makes the task of planning, prioritizing, and allocating funds a complex exercise. This paper presents a financial outlay model called PRISM, Proactive Rehabilitative Sewer Infrastructure Management, which uses linear programming to optimize allocation of funding for the local sewer network maintained by the City of Edmonton, Canada. By grouping sewer pipes into categories based on parameters of age, diameter, material type, waste types, and average depth of cover, the model provides a mechanism for determining the most appropriate allocation or appropriation of funding given a planning horizon and budgetary constraints.