FPUD approves programmable logic controller contract for reclamation plant

The Fallbrook Public Utility District approved a contract with SCADA Integrations to upgrade the conveyor system at FPUD’s Water Reclamation Plant with a programmable logic controller system.

A 5-0 FPUD board vote Monday, March 22, approved the request for proposals submission from SCADA Integrations. The upgrade will be constructed in two phases, and the contract has a total value of $128,470.

“This will automate a time-consuming function that currently must be done in person and takes about an hour each day,” Jack Bebee, FPUD general manager, said. “This will enable staff to focus on other higher-priority operations and maintenance tasks.”

The current conveyor control system at the Water Reclamation Plant can only run manually in local mode at the plant itself and uses relays and timers. Frequent inspection throughout the day is required to ensure the system’s continued operation. The system is checked each hour while it is running to ensure that the sludge is still being processed and conveyed to the correct gate and that the gate is not plugged up. The conveyor typically runs nine hours each shift, and each inspection takes an average of seven minutes. Even with the hourly inspections, the current system still fails approximately three to four times each year, in which case two FPUD staff members must clean the system and redirect solids into the digester.

“You always find things that can be done more efficiently,” Bebee said.

The ability to run the conveyor system from an operator workstation, both during a regular shift and after hours using a supervisory control and data acquisition system, would allow automatic and programmed operation of the conveyor. The automatic operation would continuously convey processed solids from the centrifuge into the sludge trailer or back into the digester. Not only would that eliminate the need for an operator to be present to inspect and confirm that the various controls of the system are working, but the controls would not need to be manually adjusted.

FPUD staff analyzed various options and decided that a programmable logic controller system would be the most efficient option. Using the PLC system rather than relays and timers would require the conveyor to be physically inspected only during the morning and afternoon plantwide rounds and readings rather than every hour. The automatic operation of the conveyor would also free up headroom in the digester tanks for influent solids and reduce preparation time for annual maintenance. The PLC system would be able to send an alarm to the operator if a plug is detected and also has the ability to open and close gates and to change the direction of the augers and screws so that the solids can be pushed through the plug or redirected to a different gate. The time savings would allow the operators to perform better maintenance of the digesters including increasing the wash down frequency of the basin, pulling out rags and debris and assisting maintenance staff with line flushing and vactoring handling lines.

A request for proposals was issued to five SCADA integrators, Jan. 15, but SCADA Integrations submitted the only bid.

“We didn’t get a ton of bids. That’s not uncommon for small SCADA projects,” Bebee said.

SCADA Integrations, which is based in Escondido, participated in the design work for the conveyor.

“We’re confident that we’re going to be able to make it a success for them,” Mark Maxfield, president of SCADA Integrations, said.

The SCADA Integrations proposal included two phases. The first phase, which will be completed before the June 30 end of fiscal year 2020-2021, will have a $51,800 cost and thus be within the 2020-2021 budgeted amount of $60,000 for Water Reclamation Plant capital projects. The second phase will be completed during fiscal year 2021-2022, and SCADA Integrations will be paid $76,670. The 2021-2022 budget will include funding for the second phase.

Joe Naiman can be reached by email at [email protected].