By Glenn Graney
High operational costs from obsolete and proprietary hardware made the water plant of Hazel Crest, Ill., increasingly difficult to maintain and repair. Its 15-year-old manual data collection and reporting system caused overtime costs to skyrocket, and outdated system replacement parts took eight weeks to receive.
Water plant operators Jerry Davis and Jim Hughes knew that their system was too old and rigid to upgrade so they began evaluating state-of-the-art automation technology, hoping to put the "end" back in "weekend." Davis and Hughes conducted more than 200 hours of research, including visiting other engineers.
They agreed that they needed a system that could adapt in a changing environment and remain a viable long-term solution to maximize Hazel Crest's investment. To meet these needs, project integrator Telemetry Process and Control (TPC) of Stillwater, Min., worked with Charlottesville, Virginia-based GE Fanuc Automation to construct a capable and flexible system that would carry Hazel Crest well into the 21st century.
Paddling out
Receiving Lake Michigan water from Harvey, Ill., the Hazel Crest water plant distributes 1.6 mgd to 14,000 Hazel Crest and East Hazel Crest residents. The facility consists of three pumping stations, three ground storage tanks, one elevated tank, one metering station and one reduced pressure valve vault. In the past, metering information, water levels, chlorine levels and all other basic functions of the plant were physically recorded, compiled, plotted and reported by only two operators.
Using GE Fanuc's open, mainstream technology at the hardware and software level, including standard programmable logic controller (PLC) components and database formats, TPC provided Hazel Crest with a solution that allowed for growth and easy maintenance. TPC constructed a system that reduces manual data collection through online instrumentation and monitoring with GE Fanuc's CimplicityRegistered software, GE Fanuc 90trademark-30 PLCs and spread spectrum radios.
Seven PLCs serve Hazel Crest's water pump stations, meter vault, elevated water tank, operation center, and the East Hazel Crest pressure reduction valve. Networked to two desktop computers via spread spectrum radios, the PLCs collect a total of 96 digital inputs, including flow switches, flood and intrusion alarms, power fails, valve and pump fails, PLC status and radio communication. Digital outputs include 36 device controls like pumps, solenoid control and audible alarms. Fifty-six analog inputs communicate the status of pressure transducers, differential pressure reducers, storage tank levels, valve positions, and transmitters for water temperature, tank weights, residuals, flow rates and air compressors. Interface modules using industry standard communication protocol Modbus RTU further demonstrate the PLCs' openness and allow adaptation as required.
Another attractive feature for Hazel Crest is the PLCs' State Logic programming.
"We specified State Logic so that any operator could easily understand it without extensive ladder logic training," Davis noted.
Hazel Crest's intake from Harvey and distribution to East Hazel Crest is monitored by Cimplicity software to prevent overcharges and undercharges. Ease of learning was a major factor in Hazel Crest's selection of the software.
"The Windows-based Cimplicity software is very user friendly," Davis said. "Point and click is much simpler to use and familiar for operators."
Cimplicity runs on Windows NT and features graphical annunciation, alarming and trending capabilities. Low tank levels, high chlorine residuals and pump failures are a few of the 96 alarm conditions captured by the software. System data is logged directly into Microsoft Excel or Access, so Hazel Crest operators can generate a variety of reports, including those required by the US Environmental Protection Agency (EPA). Reports are used for daily, weekly and monthly tracking of water and chlorine usage and calculating of excessive water use in different zones for known water main breaks. Monthly reports are distributed to the Village of Hazel Crest's manager and the board of trustees for comparison of monthly and yearly water use.
"We now have the time to produce more reports because we don't have to physically go to each station," said Davis. "Our reporting is much more precise now, too."
During the engineering phase of the project, the decision was made to use a single laptop computer as the operator interface (OI) for all Hazel Crest's master and remote locations. This decision saved a substantial amount of money, as an OI at every site was then unnecessary. With dial-in modem access to the server, the laptop provides portable diagnostic troubleshooting, so operators can diagnose and troubleshoot from home. This convenient feature allows an on-call operator increased personal freedom while automatically logging the remote access for overtime compensation.
Riding the Wave
Both operators immediately noticed one major difference after operating with the new system in place for six months. "Our overtime is cut in half," Davis said. "Now we can focus on other projects, like installing a new roof and new chlorination system and upgrading water and flow meters. We also have time to do more charts." Hughes added: "And, I have more time to ride my Harley, too, and can monitor the system from the road using the remote monitoring features."
According to Hughes, a typical trending chart formerly plotted by hand would have taken approximately half a day to produce, whereas now Cimplicity produces the same chart with greater accuracy within 15 minutes. "So far, we've cut approximately 200 hours of overtime," Davis said. "That's more than $6,000.
State-of-the-art automation is no longer limited to large, complex plants; Hazel Crest demonstrates one way in which smaller water plants can implement today's automation technology. Hazel Crest staff selected standards-based products that they could maintain themselves. This "ownership" approach helped Hazel Crest develop an automation system that meets the plant's needs, and positions the village to adapt to the inevitable changes of tomorrow.
