A leachate sump located in a remote area of a decommissioned landfill near a wetland site needs to be monitored.
The old landfill was not engineered with a liner so the sump needs to be maintained below the level of a nearby lake to prevent leachate from migrating into the environment.
Sump levels must be continually monitored, logged and recorded for regulatory compliance.
CHALLENGE
The nature of this application calls for 24/7 continuous monitoring. Initially submersible pressure sensors were tried at this site. Due to the corrosiveness of landfill leachate the sensors failed after a few months.
The equipment is mounted about 80 feet from the sump near an access road. The sensor cable was run in an underground conduit to the equipment panel.
Sensor calibration was difficult to verify once the pressure sensor was installed in the sump.
The leachate level needs to be accurately controlled to prevent overflow contamination from the landfill from migrating into the nearby wetland and eventually into the nearby stream.
SOLUTION
A LevelCom LC-400 equipped with control relays was installed on a frame near the sump. The control relays are used to directly control the pump in order to maintain the leachate level in the sump. No other pump control devices were needed.
The sump is in a remote part of the landfill site near the shore of a small lake. No compressed air is available. A high pressure nitrogen tank is used for the working gas. The LC-400 was configured to sample every 15 minutes to minimize gas usage. In this mode the Nitrogen tank lasts for over 6-7 months. The optional data logger was installed in the LC-400 to record the sump’s leachate levels. The LevelCom is accessible and is easy to calibrate. Using inexpensive PVC from a local home store for the bubbler pipe, the LC-400 provides a very cost effective solution. The LC-400 has been giving reliable service, accurate information and preventing overflows for 5+ years.