The City of Hamilton, as part of a larger real time control (RTC) project, commissioned Tetra Tech CSO to update and extend their legacy Mike Urban™ hydraulic models into a single all-pipes city-wide model.
The city-wide model will more effectively support the City's need to evaluate future developments and their potential impact on flooding or overflow conditions, as well as to access the actual annual capture rate within the collection system. The resulting model will provide a tool for the system performance evaluations in the future RTC phases, from which detailed study projects can be efficiently developed.
The City of Hamilton has a population of approximately 504,559 (source: Statistics Canada, 2006 Census of Population). Half of the former City of Hamilton is serviced by combined sewers, an area of approximately 5,000 ha, which includes the entire lower portion of the City located between the Harbour and the Niagara Escarpment, and the upper portion of the City that extends from the Escarpment Brow to Mohawk Road. Approximately 11,000 ha are served by separate sanitary sewers. This area surrounds the combined sewer area so the separate sanitary flows drain trough the combined sewers. The scope of this all-pipes hydraulic model includes the combined and separate sanitary systems as well as storm relief sewers that receive flows from the combined system in zones where partial separation has been undertaken, all tributary to both the Dundas and Woodward Avenue Wastewater Treatment Plants.
Model development included the loading of dry weather flows (sanitary and infiltration) and wet weather flows (fast and slow response components) in both the combined and separate sanitary sewer areas of the entire City. In numbers, the all-pipes city-wide model includes 22,349 catchments, 37,394 loads, 28,194 conduits, 26,700 nodes, 124 pumping stations, 10 storage tanks, 143 regulating structures, and 25 outfalls.
Tetra Tech CSO's activities within the framework of this project include:
- Model development and update from various data sources;
- Data conversion, transfer and engineering validation;
- Tracking of data sources providing detailed reference data to the modelers;
- Resolution of missing or suspect data within the source documents;
- As-built drawing research for most of the regulating structures, storage tanks and pumping stations;
- Detailed analysis of the model loading for both dry and wet weather flows;
- Model calibration for observed data from numerous flow meter sites for both dry and wet weather flows;
- Model validation by comparison to historical flooding and overflow events.
This commission included model data from multiple sources, the modeling of a high number of special structures, hydraulic analysis of a highly interconnected collection network, as well as the representation and calibration of wet weather responses using the Mike Urban™ Kinematic Wave Model B routine to represent the directly connected runoff sources from impervious areas and the Mike Urban™ RDII routine to represent the hydrological processes of previous areas, both surface runoff from previous areas and subsurface infiltration/inflow contributions.