CSO Control Plan – Optimization of the Wilmington Sewer Network using Real Time Control

Since the early 1990's, the City of Wilmington has been implementing a series of long term control plan (LTCP) improvement projects in order to reduce CSO events and to increase the annual average flow captured for treatment.

One of the key components of the City’s LTCP consists of implementing a coordinated system-wide real time control (RTC) solution to better manage flows in the collection system in order to maximize available storage, conveyance and treatment capacities.

The RTC project in Wilmington encompasses the design, retrofitting, and implementation of four control stations, the control of the three existing siphons, and the design and implementation of a central station and a new SCADA system of data collection and measuring sites for monitoring and control purposes.  All of the local stations are linked to the central station via a telemetry system. The Csoft™ software optimizer manages the system automatically from the central station, under the supervision of operators.

More specifically, Tetra Tech CSO carried out the following activities:

  • Assistance in developing the LTCP;
  • Hydraulic design, including control chamber retrofitting;
  • Automation and I&C design, including SCADA, central station, IT system, and monitoring network;
  • Detailed specifications of monitoring and control equipment, including level meters, flow meters, rain gauges, motorized gates, and control panels;
  • Detailed specifications of the IT and networking equipment, including computer hardware and software, VPN routers, fiber optics, and wired and wireless data services;
  • Installation and programming of the SCADA system, including the HMI, historian, PLCs, database servers, telemetry system and new instrumentation and control equipment;
  • Installation of new uninterruptible power supplies and air conditioning units;
  • RTC system start-up, including the factory acceptance tests, loop calibration for sluice gates, field calibration of all instruments, and telemetry systems configuration and optimization;
  • System integration, including design and programming of the PLC controls, graphic interfaces for operators, historian databases, alarm notifications, as well as web-based supervisory tools for RTC application, rainfall monitoring and remote management of IT and networking equipment;
  • Layout of new control and operation rooms to integrate high availability servers, taking into account specific operation and maintenance requirements;
  • Training of operators, shift supervisors and city engineers;
  • Developing and maintaining a web portal with secure access for information and data sharing;
  • Technical assistance and weekly system performance reports.


Average % of CSO Reduction:                    76%

Capital Investment Savings:                       $87M

"We'd have to tear up several parks in the city to build more tanks. I'm not a scientist, but we knew there had to be ways to divert the way water flows in pipes.  We are among the selected communities that have utilized Real Time Control that makes optimum use of our sewer capacity to manage and minimize overflows. This plan is cheaper, quicker and actually increases the amount of overflow we're trying to catch. The Enhanced LTCP would increase the CSO capture and treatment rate to 87% or higher, reduce CSO control costs by more than $87 million, and accelerate implementation by ten years.”

                 – Mayor James M. Baker, City of Wilmington, Delaware


Key Contact

Diana Tao

Director of Business Development
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514-257-2427 Ext: 3306
Toll Free: 877-292-5100