ESTABLISHING A SEWER MODELING OPERATIONAL UNIT IN A MODERN WASTEWATER MANAGEMENT UTILITY

In April 2003 the Metropolitan Sewer District of Greater Cincinnati (MSDGC) completed development and calibration of the System Wide Model of its combined and separate sanitary sewer systems – a three-year, 14 million effort. The model provides a comprehensive simulation tool, with nearly 43,000 model sewer conduits representing all sanitary sewers 12-inches in diameter or larger, and all combined sewers 18-inches in diameter and larger, comprising 1,551 miles of the MSDGC sewer system. The sanitary and combined sewersheds, totaling 257 square miles in area, were delineated into more than 26,000 individual catchments, enabling the system to be modeled at a very fine level of detail. This high degree of resolution was supported during model calibration by the use of more than 300 individual flow monitoring sites at which flow monitoring data (both flow rate and level) were collected. Rainfall data collected concurrently with the use of both ground-based rain gauges and radar-rainfall data collected at the National Weather Service's Wilmington, Ohio NEXRAD radar installation were used with the flow monitoring data for detailed calibration and verification of the model.It is essential that such a large investment produce a resource of commensurate value. For this modeling resource to provide that value it is essential that it be fully integrated into the organization and be used to support its various planning, design and operational functions. To remain valuable, the model must be also be sustained by continuous investment in staff, data, modeling software and supporting computer hardware/software. The on-going investment in the model also requires an organizational commitment to fund the various resources (e.g. staff costs, computer hardware, software, etc.) and a model caretaker role must be established, filled and tasked with model application, maintenance and updating.This paper describes the process developed and applied to establish the caretaker role and the manner in which that role has evolved within the MSDGC organization and contributed to its mission since the April 2003 roll-out. The caretaker role is handled by a team of modeling specialists, who support a wide range of internal “customers”. Customers include planners, operations managers, and design project managers throughout the MSDGC organization who use the modeling results to help them make decisions. This customer base was established early in the model development process, and nurtured throughout that process to ensure that the model would be accepted and trusted by those within MSD outside the modeling team.Examples of project applications and the role of the model in MSDGC operations are described. Also described is an example of how one of the new technologies introduced to the organization during the model development process – radar-rainfall data collection and processing – was adapted and expanded into a new resource for use by staff across the organization.