AutoPumps Manage Landfill Leachate to Keep Methane Flowing
Brown County East Landfill in Green Bay, Wisconsin recently completed a feasibility study that determined it would be economically sound to convert methane gas into electrical energy by electric generators to the site. Two new Cat 3516A+ engines are projected to come online in December of this year, housed in a new 30 x 100 ft building that will also contain the other gas processing equipment.
"We will be able to process 620 cfm through the system, enough to generate energy for 2,000 homes" says Chad Doverspike, Brown County Port and Solid Waste Department, Facility Manager. Historically, the landfill has flared off the gas collected from these wells and will continue to do so until the engines start running.
An important aspect of generating power from landfill gas is ensuring that methane collection rates meet project goals. The most common cause of reduced methane collection rates is the buildup of liquids in the gas extraction wells and collection system, hindering the easy flow of gas through the system. To address this concern, Brown County has been using AutoPump® air-powered automatic pumps from QED for several years to pump leachate and condensate from gas wells to keep the methane flowing at a high rate.
"We have over 130 wells using QED pumps at the East and West Landfill. The pumps have worked very well for us. Due to the severe duty and difficult conditions the pumps operate under they have to be cleaned occasionally. Some troublesome wells require us to pull the pumps yearly for cleaning. The pumps are easy to pull apart and clean on site. Landfill leachate is pretty tough to pump."
The QED pumps continue to manage the liquids at the landfill and keep the methane production at peak volume to realize the site's projected energy goals.
Variable flow rate needs are part of the pumping challenge at Brown County's landfills. Craig Wirtz, Brown County Solid Waste Technician, says: "There are several variables that affect the flow rate needed at each well, including well depth (head), where the well is located in the landfill and whether there is a clay liner or a clay-plastic liner. Some parts of our landfills have only a thin clay liner that varies greatly (0.5-6 ft). Areas that have a thin clay liner (0.5 ft) can cause the pumps to run continuously during the spring thaw with flow rates from 250-600 gallons a day.”
“Another variable is the type of garbage that the well is in - some areas of our landfill have paper waste that is so tight that it gives up little leachate (10-50 gallons per day)." A key advantage of the QED AutoPump is its ability to respond to these varying flow rate needs. Every AutoPump has built in level control that allows the pump to turn on and off depending upon whether or not there is liquid available to pump. This is a big advantage over pumps that have no built-in control and can burn out when they run dry.
Chad Doverspike has been very pleased with the service. "QED has been very responsive to our needs. Our local QED representative, Tom Lawn, has been involved with our site since the initial feasibility study through the installation of the first pumps. He continues to assist us with technical needs and management of the leachate pumping system currently in operation. We have been very pleased with the support we have and continue to receive from the entire QED organization."
Brown County operates two landfills. The East landfill (5,400,000 tons of waste), opened in 1976 will be the site of the LFGTE plant. The West Landfill (3,800,000), opened one year later, has the potential to come on-line.