When the City of Hamilton found that a section of the major Ferguson Avenue North sewer was in poor repair, it considered both replacement and in-place rehabilitation. Rehabilitation could be undertaken at significantly lower cost than replacement and was, therefore, the preferred solution.

Before the City could make a final decision to re-line the sewer, it was necessary to evaluate existing and future flows to verify that the capacity of the rehabilitated sewer would be sufficient to meet existing and future demands. The City requested Robinson Consultants to undertake the necessary analyses to establish existing flows and capacities, and produce future sanitary flow estimates.

Since much of the area has combined sewers, peak flow
is controlled by rainfall events. Flow to the Ferguson Avenue sewer is regulated by a number of overflow structures. Robinson Consultants selected the hydrologic SWMHYMO model to simulate flows. The model was calibrated using flow monitoring results at two locations within the watershed.

The study concluded that the capacity of the sewer is adequate to proceed with rehabilitation. As part of the study, modelling software was provided to the City. The extra cost of software was covered within the existing budget.