Technology: Leachate Tank Remote Monitoring

A closed landfill containing an above-ground leachate tank and pumping equipment. The leachate tank and pump system’s primary components include a wet-well (maintenance hole) and submersible pump, an above-ground storage tank, a discharge pump, and two flow meters. Landfill liquids are pumped and drain into the maintenance hole, then pumped into the above-ground storage tank. The leachate is pumped from the above-ground storage tank and into trucks that haul it off-site for disposal.

Challenges – Planning for and verifying leachate amounts, alerts for leaks, fouling, outflows

The leachate haulers want to know how many trucks were necessary each day to haul the leachate off-site. The landfill operator wanted to determine the leachate amount remotely and verify that invoicing for hauling and disposal was correct.

The SCS Remote Monitoring and Control® system (RMC) system provides the solution by connecting to the leachate tank and associated pumping equipment. The system records data and allows users to view it remotely. The system sends out text messages and email alarms, and it allows operations staff to troubleshoot and repair the system remotely.

Outcomes and Benefits

The system continues to work well since its 2013 installation. It is a valuable tool for the client, the leachate haulers, and engineering and O&M service support teams. Some of the benefits include:

Leachate quantity: The leachate haulers know, on any day, how much leachate needs to transport off-site to dispatch the exact truck size and time. Data conveys to haulers through a cellular internet connection to the SCS RMC® system. With client permission, haulers access the specific tank volume and flow data from smartphones without leaving the truck.

Data insight: The system enables SCS to monitor the leachate tank remotely and quickly do several tasks, including:

• Reviewing the leachate hauler’s manifests against the recorded tank outflow volumes,
• Identifying problems in the leachate conveyance system by tracking normal leachate volumes and identifying and pinpointing causes of decreased volumes,
• Better planning for inclement weather events that can increase leachate or freeze pipes,
• Providing monthly reports related to the leachate system.

Alarms: Replacing the control system autodialer with SCS RMC® system alarms enables replicating the previous alarms and added preventative value. New alarms include:

• Tank outflow: Leaks are a concern with any tank system. Consequently, the system alerts the appropriate staff or management when the flow leaves the tank and again when the flow stops. When either of the alarms is active, the system indicates the current outflow and totalized outflows. Having the data provides an alert for potential leaks and a record of how much liquid the hauler removes.
• Freeze warnings: For children, cold weather and snow bring joy. For landfill operators, cold weather and snow can bring headaches with freezing pipes and equipment. Using a series of thermocouples in the flow meter enclosures, an alert issues when the measured temperature drops below a setpoint. The landfill staff avoids problems with heating equipment before the pipes freeze.
• Flow meter fouling: At this particular landfill, the leachate develops black tar-like deposits on surfaces. After reviewing the flow data, SCS could identify deposits fouling the leachate flow meters, despite their non-stick coating. The fouling causes the flow meters to under-report the flow rates. Now the system alerts staff when the average measured flows drop below a predetermined setpoint. Landfill operators have time to clean the flow meters before they under-report the flow.