Heat generation in landfills is a natural phenomenon. It happens in every landfill to a degree. Heat generation in landfills accepting organic matter occurs to a higher degree due to organic material biological degradation. Subtitle D landfills accepting organic matter also accept other types of materials that can chemically react under specific conditions to generate additional heat through exothermic reactions.
Recent experience has shown that deep landfills with high levels of organic matter and high levels of moisture in the waste column can potentially create conditions deep within the landfill so that the heat generated cannot escape from the landfill boundaries fast enough. As a result, heat accumulates in the landfill and creates the condition known as elevated temperature landfill or ETLF.
The accumulation of heat causes rising temperatures within the landfill that can adversely affect the beneficial biological degradation of organic waste. Beneficial degradation of organic matter generates methane that is captured by the landfill gas control and collection system (GCCS) and in many instances converted to energy through highly technologically sophisticated systems.
Adversely affected biological degradation of organic waste under high-temperature conditions causes significant increases in the generation of carbon dioxide, hydrogen, and other gasses that have no economic value and can cause other environmental challenges, including regulatory compliance and increased public scrutiny. Additionally, control systems placed in service to address conditions resulting from elevated temperatures can be costly.
If you manage a deep and wet landfill with significant organic matter in your waste stream, you should consider design and operational steps to mitigate future operational and compliance challenges. These might include new engineered features to enhance liquids, gas, and heat removal from the deeper parts of the landfill. Many of the major landfill companies are currently designing and constructing systems to expedite the movement of water and gas through the waste column, which is a great help to potentially minimizing heat accumulations in the landfill.
Significant research work is currently underway to find out causes of heat accumulation in landfills, but it may take years before accurate cause and effect of such complex and inter-relating processes are more clearly determined, and solutions developed. Heat removal by landfill gas and leachate takes place on a regular basis, but the quantities are insignificant to affect a major reduction in accumulated heat in the landfill.
SCS is an expert in the management of elevated temperature landfills and has been promoting the development of heat management systems over the past several years. As a result, we are highly qualified to address heat accumulation in landfills and development of heat removal systems to control temperatures below the landfill surface. If you have an elevated temperature landfill at your facility or a landfill that seems to be progressing in the direction of becoming an elevated temperature landfill in the future, contact us and let us review field data from your facility and develop means to control temperatures below the landfill surface.
Author: Ali Khatami, PhD, PE, LEP, CGC, is a project director and a vice president of SCS Engineers. He is also our National Expert for Landfill Design and Construction Quality Assurance. He has nearly 40 years of research and professional experience in mechanical, structural, and civil engineering.
SCS Engineers recently added ammonia refrigeration Process Safety Management and Risk Management Program (PSM/RMP) Project Director William Lape to their professional team working with industrial clients. Mr. Lape joins the SCS Tracer Environmental team in the firm’s Minneapolis–St. Paul, Minnesota office.
Lape brings his expertise and established reputation as a plant engineering manager, senior environmental health and safety manager, and as the director of environmental health and safety – Process Safety, at Dean Foods (NYSE: DF). Dean Foods is a multi-billion dollar American food and beverage company, and the largest dairy company in the United States.
Ammonia refrigeration is a well-proven and effective refrigerant. It does require special programs and safety precautions called PSM/RMP. Lape’s education, expertise, and experience qualify him for the SCS team who hold safety and efficiency paramount. His experience includes senior positions in the food processing industry, direct management of facility operations and environmental compliance programs. Lape will support SCS clients with refrigeration and food industry changes and energy conservation initiatives while helping to keep their employees and facilities safe from potential toxicity and flammability events.
Lape is also a regulatory lobbyist for the Ammonia Refrigeration industry and is expert in developing and conducting technical and safety training classes. His process safety expertise includes Management of Change, Mechanical Integrity, Compliance Auditing, Process Hazard Analysis facilitation, and writing Operating Procedures. His experience also includes: developing release scenarios and preparing RMP submissions; operating and maintaining large industrial ammonia refrigeration systems; project management with scope and specification generation, cost estimating, scheduling, project oversight and commissioning.
He is formally educated and degreed from Purdue University, an active member in the Refrigerating Engineers and Technicians Association (RETA), sitting on their Board of Directors, and in the International Institute of Ammonia Refrigeration (IIAR) on both the Code and Standards Committees. He has multiple RETA and IIAR certifications; is CVI Certified for U.S Dept. of Homeland Security CFATS, and trained in RCRA & DOT Hazardous Materials Reporting.
“Bill is supporting SCS’s rapid growth in the Upper Midwest and Central U.S. industrial operations by providing increased safety and efficiencies to our private and government clients,” stated Thomas Rappolt, a vice president at SCS Engineers, and office director of SCS Tracer Environmental. “Our customers in the region and nationally will benefit from his valuable expertise managing the staff and protocol for safe and efficient multi-facility and multi-disciplinary facility needs.”
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Typical designs of landfill disposal cells include two slopes, one at the landfill base and the other along the leachate collection pipe. The drainage layer covering the entire cell base area follows the slope of the base toward the leachate collection pipe, and the flow in the leachate collection pipe follows the pipe slope. With the growth in the application of geosynthetics in the landfill industry, the majority of modern landfill designs include a geocomposite drainage layer, unless a granular material is readily available at an economically viable cost in the area of the landfill, which can replace the geocomposite material.
Base slopes are designed to maintain a positive flow toward the leachate collection pipe after long-term settlements of the foundation. In addition to this requirement, sometimes solid waste rules require either a minimum slope at the time of the design or a minimum slope after foundation settlement.
Regulatory agencies go through a comprehensive review process to make sure that such matters are addressed in a solid permit application involving the design of new disposal cells. However, sometimes designers propose slopes that seem to be significantly steeper than the minimum values required in the rules with no supporting foundation settlement analysis to justify the need for the steeper slopes. Slopes steeper than what is required (technically or regulatory-wise) have two drawbacks: 1) loss of the airspace which otherwise would be captured with a less steep slope; 2) lower liquid transmissivity in the geocomposite drainage layer. Laboratory experiments have shown that transmissivity of geocomposites reduces as gradient increases. This phenomenon may be related to higher turbulence in the flow of leachate through the geocomposite voids. The flow path of liquids within the geocomposite structure includes vertical and horizontal barriers that liquid flows around or over within the geocomposite thickness. Steeper slopes increase the velocity of liquids through the geocomposite, and higher velocity makes the flow more turbulent, and the higher turbulence reduces transmissivity.
One of the most important regulatory requirements on a landfill’s bottom lining system drainage layer is that the maximum head of leachate over the liner should not exceed 1 ft. When this requirement was developed, the consensus was that the drainage layer consisted of granular materials. Later, when geonets and geocomposites entered the market, the unwritten consensus among solid waste engineers and regulators was that the maximum head of leachate at the base should not exceed the thickness of the geonet or geocomposite drainage layer. With that in mind, the reduction in transmissivity of geocomposite laid over steeper slopes can adversely impact the maximum leachate head over the liner. Maximum leachate head is normally calculated from the theoretical model (along with some simplifications to disregard very small terms in the theoretical model) developed by C. A. Moore, J.P. Giroud, B. M. McEnroe, and others. One of these models was later incorporated into the Hydrologic Evaluation of Landfill Performance (HELP) model that is currently used by almost all solid waste engineers in the industry. Such model includes a parameter called hydraulic conductivity which is calculated from the transmissivity value of the geocomposite drainage layer. When transmissivity value reduces due to steeper slope at the base, the hydraulic conductivity reduces in turn as well. In the Moore’s and Giroud’s models, the maximum head of leachate is somewhat inversely proportional to the square roots of the hydraulic conductivity, which means the reducing hydraulic conductivity results in an increase in the maximum head of leachate passing through the geocomposite. The relationship between the leachate maximum head and the hydraulic conductivity is a lot more complicated in McEnroe’s model.
It’s recommended that the minimum base slope be initially determined based on foundation settlement. Then, the calculated minimum slope compared to the required value in the solid waste regulations, if any. If the rules require a minimum slope at the time of the design, pick the regulatory value if higher than the calculated minimum slope; otherwise, pick the calculated minimum slope. If the rules require a minimum slope after foundation settlement, then add the calculated minimum slope to the minimum slope in the rules and use that in the design.
A 1 percent slope at the base, provided all requirements are met, seems to be a suitable slope. The geocomposite transmissivity at 1 percent is higher than the transmissivity at 2 percent, and the space difference between the 1 percent and 2 percent slopes can be added to the landfill airspace for waste disposal.
Author: Ali Khatami, PhD, PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design and Construction Quality Assurance.
Landfill Design – Information and Case Studies
Optical sorters and robotic sorters may work in two different areas of an MRF. For heavy volumes of a few related commodities (i.e., plastic containers) the optical sorters would be located closer to the front end of the MRF, potentially following an initial separation of light materials versus heavy materials or two-dimensional items such as fiber and paper from three-dimensional items (i.e., containers) by other equipment such as a screen or drum.
In general, a robotic sorter would likely perform better anywhere in the MRF where there is some presorting to spread material evenly across the belt and remove oversize and bulky material, or two-dimensional material like paper and foil, that can obscure the targeted materials. An MRF’s control systems are typically upgraded when optics or robotics are installed to provide the operator more local control of all sorting equipment on the line, more flexibility to address waste stream changes, and simpler control interfaces.
Read up on system information via trade publications; inquire about system performance with other operators; and talk with experienced consultants and vendors. These options will help you narrow down the best option for a facility’s needs. This same information can then be used as a resource when vetting providers.
Allow companies to come into your facility and make an initial assessment, review data you may have on material volume, material changes, and percent recovery and residue. Then request a written report. That report should include: feasibility of employing the machine(s); expected tangible improvements (i.e., rate of recovery, reduction of residue, removal of additional targeted material(s), etc.; any other modifications needed to your system to allow the new equipment to perform properly, a budget cost estimate or range, and estimated operating costs.
Send a representative waste stream sample to potential vendors and have the sample run through the vendor’s test facilities to gauge the equipment’s effectiveness. Operators should visit facilities currently running the equipment under consideration for purchase to see how it operates in person. If visiting a site isn’t possible, review a site’s system layout and analyze its efficiency results.
SCS Engineers continues to expand and advance its team of environmental professionals in Northern California by welcoming Wendell L. Minshew, a licensed professional engineer specializing in civil engineering.
“As a highly-qualified addition to the team, Wendell will help SCS Engineers provide exceptional environmental service to our clients in Northern California,” said Ambrose McCready, Vice President with SCS Engineers. “His significant background in engineering strengthens our regional team, and helps ensure we meet and exceed client objectives.”
With more than 30 years of engineering experience, Minshew specializes in leading the design, planning, permitting and construction management of solid and hazardous waste facilities. He obtained his Bachelor of Science in civil engineering from CSU Fresno and is a licensed Professional Engineer in California, Nevada, Oregon, and Arizona.
SCS serves Northern California through our offices in the San Francisco Peninsula, Sacramento, Oakland, Modesto, Santa Rosa, and Pleasanton. See our nationwide locations.
Many schools and school districts are prioritizing a shift toward zero waste and sustainability. However, learning to manage material resources on-site in a more sustainable manner presents operational and monetary challenges. Learn the benefits and steps to plan a financially sustainable program from Tracie Bills of SCS Engineers.
Tracie creates realistic approaches which allow for flexibility while maneuvering the unique challenges that occur. She takes you step-by-step through building a successful program and refers to established efforts such as in the City of San Jose that already have established zero waste programs in their schools.
Read the article by clicking here.
A fire at your transfer station or MRF can cause significant downtime, lost revenue, and added cost to restore the damaged equipment and building components. The fire department can tear a metal building apart just fighting the fire. Fires can also trigger negative publicity and could result in injury or even loss of life. Even with automatic sprinkler systems in place, fires can spread quickly. Traditional fire sprinklers are designed to protect the building from completely burning down. However, in most solid waste processing facilities, they are mounted relatively high in the building. Placement can result in significantly delayed response times to react to a fire which has time to grow and propagate. The delay can result in significant damage to structural elements, insulation, lighting, electrical, roof, and wall panels.
International Fire Protection recently published an article by Ryan Fogelman suggesting an investment in more effective fire technology safety systems to prevent fire incidents rather than mitigating the damage. The author’s solution is using automated detection of excessive heat using military grade thermal detection to pinpoint the exact location, with automated emergency alerts, remote human verification, and remotely controlled coolants to contain the threat of fire. These are all innovative solutions and certainly seem logical to help MRFs, transfer stations, and composting operations minimize the chance of an expensive emergency that could shut down operations.
Now we face the dilemma of how public agencies and businesses can afford the new or improved technology.
SCS Engineers believes that preventative strategies and designs are superior and in the long term are safer and less costly. For example, system costs typically include the monthly 24/7 monitoring and operation and set up for multi-year periods (e.g., ten years). At one MRF that experienced a fire, SCS Engineers estimated the cost to install, monitor, and maintain a 24/7 fire suppression system for the 10-year period was less than the cost of the single fire incident. Operators and owners are challenged with a business problem that requires integrating specialized engineering and technology expertise with financial expertise to create operational efficiencies.
When estimating the cost of new technologies to mitigate emergencies and increase safety, the financial considerations are paramount. Elected officials, public works directors, private sector waste management decision-makers and public utilities must operate efficiently while providing critical community services, and maintain existing service levels. They must do so while keeping rates, fees, taxes, and assessments as low as possible for the residents of a community.
Environmentally sustainable solutions must be economically feasible to achieve consensus by constituents and shareholders.
SCS Management Services™ supports a comprehensive approach to environmental solutions as described in International Fire Protection, by providing financial experts who work in combination with our engineering and technology consultants to design solutions that support MRFs, transfer stations, and composting operations planning for long-term economic and financial sustainability.
Duluth, GA – SCS Engineers, a leader in environmental and solid waste engineering, recently relocated from Alpharetta to a larger, more strategically located office in Duluth, Georgia. The new office supports SCS’s continued development in the Southeast, our client success-driven growth, and accommodates our growing professional staff.
SCS is always on the lookout for talented senior level professionals in the environmental consulting community. The Atlanta Environmental Services (ES) group is seeking experienced, humble, hungry, and smart senior level consultants with client relationships and business development capabilities to join our team.
SCS Engineers – Atlanta
3175 Satellite Blvd
Building 600, Suite 100
Duluth, GA 30096
(678) 319-9849
If you are interested or know anybody who is interested, reach out to . You may also review our open positions on the SCS Careers Page.
June is the start of hurricane season and the time to check that your preparations for the safe and timely management of debris are ready. Debris removal and management are just two of the many competing priorities public agencies must manage during such events. It is important that disaster debris is properly managed so as to protect human health, comply with regulations, conserve disposal capacity, reduce injuries, and minimize or prevent environmental impacts.
Advance thought, planning, and coordination among individuals at various levels of government and the private sector with experience and expertise in waste management can successfully meet challenges from even the more severe storms the nation has experienced in recent years. Hammering out removal details with multiple jurisdictions and multiple contractors once the storm ends generates mountains of paperwork that must be submitted to the Federal Emergency Management Agency (FEMA) within six months. Not preparing for as many of the administrative aspects of a disaster as possible can have painful bottom-line consequences. These tedious, detail-oriented tasks conducted under great stress, can create the errors that federal agencies use to decline reimbursement applications.
Get started with these resources and recovery success studies; click to read, download, or share each:
Contact for assistance starting or refining your plan ahead of natural disasters.
Planning for Natural Disaster Debris – help for communities to develop or revise a disaster debris management plan. Many aspects of disaster debris planning can be relevant to communities demolishing abandoned residential buildings and remediating properties.
Guidance about Planning for Natural Disaster Debris – much of the construction or demolition waste can be recovered and recycled. SCS Engineers designs and builds these facilities so we can help locate the nearest C&D debris recyclers as part of your plan.
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