This animation illustrates how a standard Polychem chain and flight scraper system is assembled and installed.
The city of Shreveport, La., has been a landmark for water treatment facilities for more than 100 years. Construction on the McNeill Street Pumping Station, which ran on steam-driven pumps, began in 1887.
Major additions were undertaken from 1899 to 1921 and the plant continued to operate until 1994. The McNeill Plant is typical of waterworks from the early 1900s that were once common throughout the U.S. Not only is the steam-powered machinery dated from the late 1800s still intact in its original historic location, but the two Worthington pumps are still operational, thanks to meticulous care and maintenance.
When the Thomas L. Amiss Water Treatment Plant, built in 1929, needed updating, the city of Shreveport decided to keep the beautiful historic building while providing the control center with the latest technology.
Today, the T.L. Amiss Plant provides 90 million gal of safe drinking water to more than 70,000 Shreveport residents. A CitectSCADA system is used to monitor the level indicators, flowmeters and historical trends of a distribution system consisting of 1,049 miles of water mains, 11,400 water main valves and 6,100 fire hydrants.
Shreveport also operates two wastewater treatment plants: the Lucas Wastewater Treatment Plant and the North Regional Wastewater Treatment Plant. This system contains of 1,027 miles of sewer mains, 104 sewer lift stations and two equalization basins.
The Lucas Wastewater Treatment Plant is a “secondary” treatment plant utilizing biological activated sludge treatment and final clarification. The plant is designed to remove up to 90% of the pollutants contained in the raw wastewater received at the inlet to the plant.
Shreveport needed to upgrade its Supervisory Control & Data Acquisition (SCADA) system, used to monitor and control the collection, treatment and distribution of water and wastewater. Like many cities, Shreveport was faced with difficulties common to the water/wastewater treatment industry. The city was using multiple plant and remote terminal unit (RTU) controllers, many of which were nonfunctional or obsolete. In addition, the existing RTUs were supplied by a defunct company, which made obtaining upgrades and support impossible.
The different SCADA platforms at each plant created maintenance difficulties as well. Each plant was isolated with no ability to exchange data between them.
The various communication protocols and hardware configurations created intermittent connectivity problems and system lockups within the plants. Long communication delays and slow network response made it difficult for operators to detect equipment failures.
Citect Platinum Integrator and Edison Automation, in close partnership with Citect Professional Services, were initially awarded a contract with the city to install the SCADA system at the T.L. Amiss Water Treatment Plant to monitor and control the water treatment process, the water distribution system, and the wastewater collection system.
As a result of the project’s success, the T.L. Amiss Water Treatment Plant became a prototype for defining the control system infrastructure standards for future upgrades at other plants. The SCADA system was then expanded to both the Lucas Wastewater Plant and North Regional Wastewater Plant to complete the citywide system.
Each plant required a user-friendly, reliable SCADA system with fast response times, consistent color schemes and well-documented design standards. The long-range goal was to establish the same technical guidelines and specifications by standardizing on a SCADA platform, enabling the plants and remote sites to function as a single, consolidated system. Built on an open architecture, the system would also easily permit future improvements in control and data management.
One of the largest issues facing Shreveport was the high number of disparate systems. Remedying this problem was easy and inexpensive because all the drivers needed were already included in the SCADA package.
Reliability was also an important concern. System failure would result in inaccurate information and large overtime costs. The new system has redundant servers that act as immediate back-ups in case of a failure. Each of the four subsystems also has fully redundant servers to ensure reliability and maximize on-stream time. A separate set of servers maintains the communications to the collection system RTUs.
Prior to implementing the system, users had to either visit each site or access remote sites one at a time over the network. This made monitoring all the sites very time-consuming and expensive. Furthermore, it might take long periods of time to detect a problem at one of the various sites.
By standardizing on a CitectSCADA platform for all its operations, users have the same look and feel wherever they log into the system.
Security is a top priority at Shreveport, though monitoring and controlling remote equipment and resources can be an expensive and challenging undertaking. Access control and intrusion detection were simplified by coordinating security devices with the SCADA system. Inexpensive IP-based web cameras at all sites that provide video frames of remote locations are easily linked to the SCADA system. Their photos are easily and rapidly transmitted across the network, allowing operators to monitor all the sites from a single location.
Kody Salem is utilities and public infrastructure manager of business development for Edison Automation. He can be reached at 615/256-2522 or by e-mail at [email protected].