Increasing Predictability of Inflow-Infiltration Reduction Outcomes: Some Definitive Guidelines

The Water Services Association of Australia (WSAA) recently engaged GHD, in association with Urban Water Solutions, to develop a Good Practice Guideline Document on Infiltration and Inflow Management. Using the practices implemented in the examples of successful project outcomes identified during the project, a Good Practice I/I Management Guideline Document for Australian and New Zealand water utilities was developed. Locally, this document has now become the industry guideline document for I/I management programs. As a result of this work a predictive model of the likely level of I/I reduction that can be achieved from existing levels for different extents of system rehabilitation now exists. This represents a significant advancement worldwide in the planning of wastewater system improvement programs. Of greatest value is that the work gives far greater surety upon which I/I reduction programs through system rehabilitation can be planned and implemented with the expectation of certain outcomes for a given financial investment.