Strong Water and Wastewater System Backbone Affords Later Improvements

Challenge

Several years ago, we replaced all of the PLCs and the SCADA system. Now, they requested several enhancements to the existing water and wastewater system including:

• A weather station integrated into the SCADA system. This would allow the data to be displayed remotely via the webpages and it would log the weather data (such as rain totals, wind speed, wind direction, etc.) over time.
• Replace an aging lift station control panel
• Integrate an above-ground storage tank of irrigation into the existing control system.
• Integrate flowmeters for several water lines that did not have digital meters.

However, increased budget availability does not mean unlimited budget availability. Our two teams worked to make these changes as efficiently as possible.

Solution

Patti Engineering worked with the budget laid out by the City of Fair Oaks Ranch to help make the wish list match the funds. Having worked with the team before, we were familiar and able to match our services and their skills. To help accommodate the budget, Patti focused on the design of the system, while the City of Fair Oaks Ranch team performed the install of the components. Patti specified hardware and made print markups.

Weather Station

Patti Engineering had previously developed and installed an Indusoft SCADA system. Indusoft has native Modbus TCP drivers, and we were able to find a Modbus TCP weather station, allowing us to have the SCADA system connect directly to it. Patti Engineering developed the displays and added the new data to the logs.

Bottom of Hill Lift Station

The City of Fair Oaks Ranch had an aging lift station panel, which controlled two pumps via floats and relay logic. The wiring on this aging panel was hard to follow. Modifying set points required physically adjusting float switches. this station also directly fed the wastewater station. When it turned on, there would be a large amount of inrush of wastewater into that system.

To solve these annoyances, we put in a brand new panel with a Siemens 1200 PLC for overall control, Siemens G120 VFDs to drive the motor, and an analog level sensor. The updated panel wiring was greatly simplified. The VFDs made it possible to gradually increase and decrease the inflow so that there wasn’t such a shock to the treatment plant. The analog sensor gave operators variable control of the set points. In addition, all of this functionality was tied into the SCADA system, allowing control and diagnosis to be done remotely over the web.

Above Ground Irrigation Tank

Near the lift station, a take of water had relay logic that drove motor starters which were controlled by float switches. There was no connection to the SCADA system at this location at all. We wired in the motors and added an analog level sensor similar to those at the lift station. These upgrades provided all the same benefits as above, along with remote, high-level alarming made possible by the SCADA integration.

Flow Meter

Several water lines had analog-only flow meters. This meant that staff had to travel throughout the city to log values daily. To solve this, we added digital flowmeters and tied them into the local PLCs, so the flow could be totalized and logged via the SCADA system that, again, could be monitored and controlled remotely. This saves the team quite a bit of time and travel.

Results

With the upgrades, the system runs well and has more than adequate visibility into the system both remotely and historically. With better visibility of system issues throughout the city, the City has more accurate, instant results. The team has gained more time by not having to make daily trips around the city – in addition to the late-night and off-hours trips for false alarms.

The City of Fair Oaks Ranch now has a system they are very satisfied with; their wish list complete.