Remote Monitoring Washes Away Control Problems

Colorado Springs (Colo.) Utilities recently implemented a new process control system and installed new operator interface products to control, monitor and automate the treatment of wastewater, with the goal of improving system efficiency, monitoring systems from remote locations and lowering overall customer costs.

Since implementation of the new control system coincided with construction of new treatment facilities, timing and scheduling were critical to the success of the installation. The new system was designed to be brought online gradually to accommodate the startup of the new facilities.

?The implementation of the control system had to support the optimization program to be considered successful,? said Jay Hardison, Colorado Springs Utilities Plant Team Leader.

The Colorado Springs system serves more than 100,000 area customers with a combined annual flow of 17 billion gallons of wastewater. The new control system also serves the Las Vegas Street wastewater treatment facility (WWTF), the Sand Creek wastewater pump station, and provides remote monitoring of the Hanna Ranch solids handling facility.

Cleaning Up the System

The wastewater treatment process control system is configured with PLC-based controls providing full-supervisory control and data-acquisition capabilities. Eight geographically distributed Allen-Bradley PLC systems comprise the primary control layer of the system serving the Las Vegas Street wastewater treatment facility. The system includes one remote Allen-Bradley SLC 5/01 which serves the off-site Sand Creek wastewater pump station and is integrated into the process control system via a leased telephone service.

Each of the PLC systems includes an extensive remote input and output (I/O) network. In addition to serving traditional 1771 I/O racks, the remote I/O network provides a data communication interface to 14 Allen-Bradley 1336 variable frequency drives and two Allen-Bradley PanelView operator interface stations. A Data Highway Plus (DH+) network, comprised of both fiber optic segments and copper segments, serves as the primary communication network at the control layer supporting peer-to-peer communications between the PLC systems.

In the initial system configuration, four operator workstations utilized the network; however, the system recently was converted to run the Rockwell Software RSView32 Active Display Station human-machine interface program. The active display software package allows users to control and monitor plant floor applications from local and remote locations. Users can interact with, change and view automation system data using either the RSView32 Active Display Station or a Web browser.

At the Colorado Springs plant, the Active Display Clients are located on desktops throughout the facility, providing direct access to wastewater treatment data via the plant Intranet. The remote access capabilities of the Windows? NT operating system also provide operations and maintenance personnel with access to the process control system from remote locations, such as their homes. With the introduction of RSView32 Active Display, an additional server was added to the DH+ network, and the workstations moved to an Ethernet LAN.

Additionally, the Rockwell Software RSLinx communication program is used to fully develop the remote access capabilities by providing access to the DH+ network and all of the PLC processors via the plant Intranet and through dial-up access.

The View from Afar

Because of the remote monitoring capabilities offered by the new operator interface system, the Hanna Ranch solids handling facility, which processes the solids from the Las Vegas Street facility, can be monitored from the process control system at the Las Vegas Street facility. The PLC system at the Las Vegas Street facility integrates with a PLC system located at Hanna Ranch via a microwave communications system. Critical operations data and alarm events are then reported through RSView32 at the Las Vegas Street facility, allowing operators to monitor and view any problems with the water treatment process.