Technology: Landfill Gas Flare Remote Monitoring

SCS provides ongoing engineering and operations and maintenance (O&M) services for a closed landfill. The landfill contains a landfill gas (LFG) blower/flare system, LFG compression skid, and liquid handling tank (LHT).

Challenges – Power Loss, Efficient Operations, and Budget Constraints

Inclement weather and frequent power losses caused operational headaches for the LFG blower/flare system. The existing LHT control system had no alarm callout capabilities, and it had no way of stopping liquids from entering the LHT during power loss and high liquid level events. The client did not want to staff the site fully but needed coverage for the power disruptions without needing to send in a technician every time.

To help improve the blower/flare system’s operations and the LHT SCS proposed, designed, built, and installed an SCS Remote Monitoring and Control® system (RMC) system. The SCS RMC® system records data and allows users to remotely view the data from the blower/flare system and the LHT. It sends out text and email alarms, allowing users to troubleshoot remotely and repair the system. Unique to this system, it automatically stops liquids’ flow into the LHT during power loss and high liquid level events.

Outcomes and Benefits

The SCS RMC® system has been working well since installation in 2013, without the need to hire full-time staff or frequently call in a landfill technician. Some of the ways SCS uses this system are as follows:

Alarms: Alarms for events such as high and low vacuum alert SCS’s O&M personnel to key occurrences that can prevent larger problems, such as subsurface oxidation or subsurface gas migration.

Data: The SCS RMC® data recording system helps diagnose and repair mechanical and electrical problems with the blower/flare system. Examples include:

• Negative blower discharge pressure: Through a combination of received alarms and data review, SCS identified during times of high LFG demand the LFG compression system pulled hard enough on the LFG blower to create a vacuum on the discharge side of the blower. This condition causes a high vacuum to occur on the wellfield. SCS could identify and repair a problem in the Programmable Logic Control (PLC) coding that was causing the blower to slow down when there was a vacuum on the discharge side of the blower, instead of accelerating to keep up with the increased LFG demand. After addressing both issues, the number of callouts and the amount of system downtime decreased significantly.
• Air compressor problems: The landfill uses a compressed air system that powers pneumatic dewatering pumps and pneumatic valves. The SCS RMC® system measures and records compressed air pressure at two points in the compressed air system. This data is useful for evaluating the air compressors’ size, diagnosing and repairing problems with the compressed air piping system and the air compressors.

Radio system: A pair of radios maintain the connection between the blower/flare control system and the LHT control system. These devices create a wireless local area network (LAN) between the two control systems. SCS uses the wireless LAN to communicate data between the systems, including information about compressed air pressure, totalized liquid flow, the pump station’s high-level alarm, and the power status.

LHT control: Flow controls implementation on the LHT prevents the LHT from overflowing during power loss, and high incoming liquid flows.

“The SCS RMC® systems enable my client to reduce operations and maintenance (O&M) costs, remotely keep tabs on their closed landfill , and reduce potential environmental liabilities. Without a doubt, the SCS RMC® system has paid for itself,” Darrin Dillah, PE, Project Director, and Client Manager.