The Waste Management Liberty Landfill consists of seven leachate (combination of gas and water) and four water pumping stations. The pump stations pumped the leachate and water back to an effluent tank that was emptied into a truck. The stations were run off a starter that would turn off based on amps and the actual liquid level was not known. There was no communication between the pump stations and the tank, so if the tank was overflowing, the pumps would not stop.
A system needed to be designed that could monitor the level in each of the pump stations and also have the ability to stop pumping if the level of the effluent tank got too high. With the shape of the landfill and with the pump stations surrounding it in a circle, line of sight for radio communications was going to be a challenge.
Toric designed pump station control panels using combination disconnect/motor starters and Allen Bradley MicroLogix PLCs. Level transmitters were added to each pump station and the PLC controls the pump based on level. Each pump station communicates to a Master Control Panel (MCP) which has a color touchscreen where the pump on/off setpoints for each station can be manipulated. With line-of-site being a challenge, Toric designed an unlicensed spread spectrum radio network where each radio also acts as a repeater. With this design, information can be passed around the landfill while keep antenna heights at ground level, eliminating masts or antenna towers. A cellular modem was also added to the MCP, giving the customer remote access to the touchscreen from any Smartphone, tablet, or computer. With the remote access, the customer has the full capability of the touchscreen including monitoring and setpoint manipulation.