Remote wireless monitoring of landfill groundwater and leachate

The Rural City of Wangaratta in Victoria owns and operates an EPA-licensed landfill at Bowser, 6 km north of Wangaratta. The Bowser landfill has been operating since the early 1990s, accepting waste from Council's kerbside collection service, transfer stations and commercial waste contractors, and has an estimated remaining life of around 10 years if current practices and waste volumes continue. It is a challenging site as it divided in two by the Sydney-to-Melbourne four-lane Hume Highway, which was a major reason for the requirement of a wireless system.

Solar-powered pumps extract groundwater on both sides of the highway and transfer it for settling into leachate ponds. A pipe connection has been installed between the leachate ponds and the sewer system to allow for excess leachate to be disposed of more cost effectively after major rain events. This meant that the EPA required data to be logged and reported from the sumps located around both an active landfill and an unused landfill to ensure compliance with the landfill licence.

A decision was made to install a wireless remote monitoring system so that the council did not have to undertake expensive digging works or interrupt the highway. Seven OleumTech Discreet Wireless Transmitters (model SM5010-DJ1) were installed to manage the reporting of flow metering data from the sumps. They are connected to existing flow meters and vacuum pump blowers across the site.

The existing field flow meters provide 'pulse' or 'count' output (ie, one pulse output = X litres of flow) and the OleumTech Discreet Wireless DJ1 units transmit the counter inputs via low-power 900 MHz radio links to a OleumTech Wireless DH2 Gateway. The Wireless DH2 Gateway 'stores' this information in Modbus register locations and uses a serial connection to link to a Brodersen RTU32.

The Brodersen RTU32 reads the Modbus registers and displays the required data on a local HMI interface via a 15″ touch-screen monitor.

The RTU32 has a logic application running that ensures data is scaled and stored to enable the creation of daily, weekly and monthly reports. The reports are stored in the Brodersen RTU for 10 years and can be viewed via the local HMI interface or retrieved and viewed via the RTU's web server or FTP server.

The RTU32 is connected to the council's corporate WAN, which allows the RTU's email interface to send reports to relevant staff at the start of each week and every month for the previous week or month. Secure remote access is also provided for remote support, allowing changes to the RTU's application logic and set-up to be made remotely.