A recent SWANA Applied Research Foundation report explains how landfill systems and strategies can reduce odors, control surface emissions, and support methane reduction when properly designed and integrated into the broader gas collection strategy.
Capture Gas Earlier
Updated guidance on horizontal landfill gas collection systems explains how these systems can help landfill operators capture gas earlier in the active filling phase, before final grades are reached and before vertical wells can be installed. Horizontal collectors are installed laterally within the waste mass, usually in shallow trenches with perforated or slotted piping, permeable backfill, and connections to the landfill’s active vacuum system. Because they can be placed during filling, they provide a practical way to control odors, reduce surface emissions, and support methane reduction in areas where conventional vertical wells are not yet feasible.
Landfill GCCS
The report emphasizes that horizontal collectors are not a substitute for a full landfill gas collection system. They can be an important complement when coordinated with fill sequencing, interim grades, drainage conditions, and the future vertical well network. Common types include slope collectors, toe collectors, and floor collectors, each suited to different site conditions.
Leachate Management
A central theme is the importance of liquid management. Condensate and leachate can accumulate in pipes or trenches, reducing gas flow and system performance. For this reason, collectors must be designed with proper grades, accessible removal points, sumps, stone columns, or connections to the leachate drainage layer where appropriate. The report also highlights the importance of pipe selection, trench and backfill design, wellhead placement, settlement considerations, and ongoing monitoring.
Overall, the guidance presents horizontal collectors as a flexible, cost-effective tool for improving landfill gas control during active landfill development when they are carefully planned, site-specific, and integrated into the broader gas collection strategy.
Additional Landfill Gas Collection Resources:
By Ali Khatami
MSW sanitary landfills constantly face the issue of aesthetics due to leachate seeping out of the landfill slopes. Of course, the problem goes away after the construction of the final cover, but the final cover construction may not take place for many years after seeps show up on slopes. To the public, leachate seeps represent a problem with the design of the landfill and possible malfunction of the leachate collection system below the waste, which is an incorrect perception. Such arguments are common and difficult to counter.
Landfill operators use different means to control leachate seeps from landfill slopes and to clean up the unpleasant view of the seep as soon as they can. Innovative solutions to address the issue have been observed and noted in the industry. The degree of effectiveness of the solution to some extent depends on the amount of money spent to address the problem. Some landfills are located in rural areas and the operator may not mind the unpleasant appearance of the slopes, so naturally no urgency in addressing the issue or no money available to take care of the problem.
The environmental side of the leachate seep issue is the impact to surface water quality. If leachate seeps remain unresolved, liquids coming out of slope may eventually reach the landfill perimeter and mix with stormwater in the landfill perimeter ditch. At that point, the operational issue turns into a compliance issue, and regulatory agencies get involved. If the public around the site is on top of their game concerning their opposition to the landfill, they can take the non-compliance issue and turn it into a political issue. At that point, the landfill operator finds himself or herself on the hot plate dealing with the agency and the public on an environmental impact matter.
It always makes sense to stay ahead of the issues and address any potentially sensitive condition before it turns into a major problem. As discussed above, addressing leachate seeps can be done in many different ways, and the operator needs to be prepared to fight for funds to address leachate seeps as they appear on slopes. Availability of funds and willingness of the operator to take necessary action are the primary required elements to stay ahead of the game.
SCS has developed methodologies to address all sorts of leachate seeps on landfill slopes and is uniquely equipped to assist you with a solution. Reach out to a local SCS office for a consultation if you have leachate seep problem at your site.
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