The primary role of gas collection system laterals is conveying landfill gas to the final destination in the system; however, lateral pipes are also used to convey condensate in the system to a collection point such as a condensate sump. Between the gas collection laterals and the condensate sump, there are gas headers that provide vacuum to the laterals. Condensate sumps are primarily connected to gas headers for effective management of condensate in the system.
On many occasions, gas headers are installed over the landfill surface, where condensate sumps have to be constructed as well. This type design could potentially create issues during construction of the final cover system in the area. On numerous occasions, the condensate sump sticking up above the surface is too short causing the sump to be extended during the final cover construction.
The gas system in the area must be taken out of service to extend the condensate sump. Such interruptions are never welcome because odors or lack of gas productivity can cause serious issues for operators. Also, waste settlements at or around the condensate sump can cause other issues that must then be addressed during construction of the final cover. Furthermore, if the gas header connected to the condensate sump ends up in the middle of the waste column with tens of feet of waste above the gas header, there is the risk of the gas header collapsing under the waste surcharge load and causing issues in the flow of gas and condensate in the system.
Avoid problems by allowing for constructing the gas header and condensate sumps in the landfill perimeter berm.
There are major benefits when the gas headers and condensate sumps are located outside of the waste. First, settlement issues are avoided and secondly potential gas header collapse is averted because they are not situated below many tons of waste. Construction of the condensate sumps to the correct and final height is accomplished while avoiding any final cover construction delays because of issues with the condensate sump locations. In addition to these benefits, the condensate sumps are readily accessible for maintenance.
Under certain conditions construction of the perimeter, berm needs to be carried out in advance of construction of certain disposal cells to position the gas header and condensate sumps in the berm. The design adds to the planning time and requires close coordination with a landfill engineer, but the return is worth every penny.
Contact Dr. Khatami to learn more about the specific conditions that can increase your ROI.
