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SCS Engineers is a leading environmental consulting and contracting firm with over 50 years of expertise in designing, permitting, constructing, and operating landfills. The firm is a pioneering force in developing landfill design technologies in use today by most landfill designers in the United States and internationally. Dr. Khatami describes several of the more prominent of these technologies below.
Landfills without Terraces
SCS is one of the first landfill designers to develop the concept of straight-up 3:1 slopes for landfills with no terraces. The modern version of tack-on swales (also known as tack-on berms) for control of surface water runoff came about along with this concept. This technology simplified waste filling operations for landfill operators and added significant additional airspace to landfill facilities. This concept’s financial benefits for SCS’s clients over the past three decades exceed one billion dollars.
SCS developed the single-barrel downchute and double-barrel downchute systems combined with the tack-on swales for landfill slopes during final cover installation. SCS has been designing and constructing these systems since the early 1990s, and none of the constructed systems have experienced failure. System performance for such a long time is a clear indication of the design’s suitability in combination with the tack-on swales. These concepts eliminate numerous problems that arise with open surface downchutes and other downchute systems combined with terraces on landfill slopes. The construction simplicity and rapid system installation make them the most useful systems for our clients.
Leachate Toe Drain System
SCS was the first landfill designer that developed the concept of a toe drain to collect and properly dispose of leachate seeps below the final cover geomembrane. SCS coined the term leachate toe drain system or LTDS for standardizing the design over 20 years ago. The LTDS is currently an essential component of all landfill designs that experience leachate seeps on exterior slopes, and landfill designers are catching up with the concept.
Rainwater Toe Drain System
SCS was a pioneering landfill designer in developing the proper means for collecting and removing water from the final cover drainage layer located above the final cover geomembrane. SCS coined the term rainwater toe drain system, or RTDS, to standardize the design over 20 years ago. The RTDS concept is currently an integrated component of all closure projects designed and constructed by SCS and many other landfill designers.
Sustainable Landfill Design Concepts
SCS revolutionized the landfill base grades design by developing the Landfill Green Design concept over two decades ago. Many regional landfill owners welcomed the concept and its numerous benefits, including savings in construction material and increasing airspace, to name a few. Introducing the second generation of the landfill green design within a few years, SCS addressed solid waste rules in several states. The improvements apply to very long disposal cells, minimum slope values for the leachate collection pipes, and minimum slope for a disposal cell’s base area. Coining the second generation design a Landfill Green-H Design, with “H” for hybrid, SCS reflects the combination of the landfill green design concept and the traditional herringbone concept. Readers of the SCS Advice from the Field blog can look forward to an upcoming blog on the term herringbone soon!
Over the past two decades, SCS has increased the airspace of many large regional landfills by modifying their solid waste permits incorporating the first and second generations of these concepts. The savings in construction material for these facilities exceeds $130,000,000, and the added financial benefit related to extra airspace is nearly $300,000,000. These SCS design concepts not only reduce construction costs and increase landfill airspace; they also have other sustainable benefits that landfill owners and operators value to help meet their sustainability goals.
The third generation of SCS’s Landfill Green Design is now available. Landfill Green+ Design provides its predecessors’ benefits with a higher degree of sustainability to our clients.
Tiered Vertical Gas Wells
SCS developed the concept and coined Tiered Vertical Gas Well, or TVGW, for the largest waste operator in the world as part of the developing standards for preventing elevated temperature conditions forming in deep and wet landfills. TVGWs collect landfill gas from the entire vertical column of waste from the bottom lining system to the final cover system. SCS developed additional concepts for horizontal blankets and fingers around the TVGWs to improve gas collection and rapid vertical movement of leachate through the vertical column of waste, allowing leachate to migrate vertically down to the leachate collection system rapidly. TVGWs have been a necessary component of new disposal cell construction at deep and wet landfills since their introduction to the industry.
Recently, SCS developed the second generation of TVGWs, known at SCS as TVGW+. TVGW+ simplifies the construction of intermediary pads and improves the connection of the pads to the vertical wells. Horizontal blanks and fingers can integrate easily into the TVGW+.
Gas Release System at Lining System
SCS developed the concept and coined the term Gas Release System (GRS) for the largest waste operator in the world as a part of the developing standards for preventing the formation of elevated temperature conditions in deep and wet landfills. The GRS releases high-pressure landfill gas near the bottom of the landfill. Excessive pressure can adversely impact leachate flow within the geocomposite drainage layer above the lining system geomembrane. Landfill owners and operators can apply the GRS concept to non-wet or shallow landfills as long as gas pressure near the bottom lining system is an issue.
Clog-Free Leachate Collection Pipe System
Over five years ago, SCS developed a design for leachate collection pipes without geotextile, which is a primary source of clogging in the vicinity of leachate collection pipes. SCS coined the term Clog-Free LCS Pipe or CFPIPE to standardize the design. Leachate from the geosynthetic drainage layer flows directly into the gravel around the LCS pipe and then into the pipe without passing through a geotextile. Since its introduction to the industry, SCS incorporates the CFPIPE into the design of landfills requested by clients looking for sustainable and clog-free systems.
The development of these technologies and many other SCS Firsts illustrates the value that the combination of our engineers, consultants, field staff, and scientists brings to each client. Our landfill designers work in combination with other highly sophisticated landfill related technologies developed by SCS, such as landfill gas systems, renewable energy systems, SCS RMC® remote monitoring and control, SCS eTools® for data management and decision making, and stellar operation and maintenance services.
As environmental industry pioneers, we never stop striving to be the most valuable landfill full-service provider. We highlight industry Firsts on our website just beneath the photo headlines.