landfill design

UW-Madison Hosts Solid Waste Landfill Design Short Course

March 22, 2021

SCS Professional Betsy Powers will present a session at the University of Wisconsin-Madison’s on-line Short Course on Solid Waste Landfill Design, March 22-24.

Betsy will cover the Landfill Drainage and Runoff Control session.

After attending this course, you will have a firm grasp of the background and design specifics necessary to compete in this industry, including industry-leading information on the principles and practices of solid waste landfill development, design, construction, and management. Understand practical emerging technologies including polymer-based bentonite composites in geosynthetic clay liners, landfill gas containment and management for emission control and regulatory drivers, design of gas-to-energy projects, management of CCR landfills and impoundments, and characterization and management of industrial residuals.

Who Should Attend?

  • Civil engineers and landfill designers
  • Landfill owners and operators
  • Local, county, and state regulatory agency staff and officials
  • Public works professionals and municipal engineers
  • Geotechnical and geoenvironmental engineers
  • Geological engineers, hydrogeologists, and geoscientists
  • Facility managers with on-site disposal cells
  • Contractors and estimators
  • Geosynthetic manufacturers and product representative
  • Planners

Click for more details, pricing, and enrollment

 

 

Posted by Laura Dorn at 8:00 am

2021 C&D World Annual Conference

March 21, 2021

The Construction & Demolition Recycling Association (CDRA) promotes and defends the environmentally sound recycling of the more than 500 million tons of recoverable construction and demolition (C&D) materials that are generated in the United States annually. These materials include concrete, asphalt, asphalt shingles, gypsum wallboard, wood, and metals.

The 2021 Convention will be held live & in-person with your health and safety in mind. Even with these precautions, C&D World Austin will still be an exciting and interactive event for C&D recyclers from across North America.

Register Here

 

 

 

 

Posted by Diane Samuels at 12:00 am

Shall We End the Herringbone’s 50-Year Reign in Landfill Design?

February 22, 2021

Three thinkers working in different spaces.

 

In our newest SCS Advice from the Field, Ali Khatami makes his case for the landfill chevron pattern…

For at least the past 50 years, our industry has referred to the design pattern for the bottom of landfill cells as herringbone. But, it’s time to break the long-standing herringbone reign and give credit to the true holder of the crown: the chevron pattern. A chevron pattern visualizes the actual geometry used by landfill designers over the decades.

The schematic views of both patterns are shown below:

 

Now, here’s a sketch of a landfill single-cell design:

Obviously the chevron pattern!

 

Note the cell base area with elevation contours that resemble the chevron pattern, with the leachate collection pipe located along the centerline of the cell.  The cell base area is sloping toward the leachate collection pipe to convey landfill leachate at the base to the pipe, then the pipe conveys the leachate to the leachate sump located at the low end of the pipe. The pattern at the base can easily be duplicated in either direction of the cell area, developing a multi-cell design resembling the chevron pattern shown above.

In this case, the straight lines connect the low points (representing leachate collection pipes) and the high points (representing the divider berms separating adjacent cells). The zig-zag lines in the pattern remind landfill engineers of the elevation contours for the landfill bottom design geometry.

Meanwhile, with the herringbone pattern, the adjacent “tiles” or rectangular shapes are in a perpendicular position to each other and do not resemble the zig-zag lines in the chevron pattern. The herringbone pattern cannot be representative of the elevation contours, leachate collection pipes, and the boundary lines between adjacent cells like the chevron pattern. Additionally, the angle of line segments in the zig-zag in the chevron pattern can vary to any desirable value, which allows representation of changes to the disposal cell base slope (an important parameter in landfill design).  On the contrary, the tile position in the herringbone pattern has to maintain perpendicular angles throughout and therefore it loses the ability to represent various base slopes.

One may draw lines along interface boundaries of the herringbone features and come up with the chevron pattern. But why stretch the truth when the chevron is already clearly the pattern?  It is not apparent how or why the herringbone association took hold in the first place, but it’s about time that changed.

Admittedly, it took nearly four years to scientifically support the validity of the Special Relativity Theory from the time it was published by Albert Einstein in 1916. And it took nearly 50 years to physically detect the existence of Higgs boson particle from the time it was theorized by Peter Higgs in 1964. So, I suppose we can wait for formal recognition of chevron designation for landfill design.

 

Why such a big deal!?

The chevron validation may be insignificant compared to the scientific validations of Einstein’s and Higgs’ work. For landfill engineers, attune to details, it could be considered big because anything new, and more accurate in the landfill design field is a cheering matter!

Throughout the history of science, new findings supported by scientific evidence have replaced prior theories or concepts when progress is desired.  Change of the pattern association, in this case, may not qualify as a scientific finding; however, it is a clear and noteworthy correction to what landfill engineers have been using over the past many years.

 

About the Author:

Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering.

 

 

 

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

Advice from the Field: Landfill Partial Final Covers and Associated Features

December 28, 2020

web version

State regulatory agencies normally require landfill slopes reaching final grades to close within a certain period. This requirement leads to closing landfill slopes in phases, normally referred to as partial closure. Generally, partial closures start from the bottom of the landfill slope up to a certain elevation, with geosynthetics in the final cover temporarily anchored along the partial closure’s sides and upper boundary. Engineers propose different designs for securing the lower boundary of partial closures at the bottom of the landfill slope. Some engineers propose an anchor trench outside the bottom lining system anchor trench to secure the final cover geosynthetics. Others specify welding the cover geomembrane to the bottom lining system geomembrane.

 

Anchor Trench for Final Cover Geosynthetics at the Bottom of the Slope

Experience with anchor trenches at the bottom of the landfill slope for the final cover geosynthetics has not been positive because of these issues:

  • Landfill gas may escape through the opening between the bottom lining system anchor trench and the final cover anchor trench.
  • Leachate seeps below the final cover geomembrane that reaches the bottom of the landfill slope may penetrate the landfill perimeter berm through the opening between the two anchor trenches.
  • High concentrations of landfill gas may be detected along the landfill perimeter berm at the location of the two anchor trenches during surface emissions monitoring.
  • If high leachate levels are developing inside the landfill cell, landfill leachate may escape through the opening between the two anchor trenches.

 

Welding of Final Cover Geomembrane to the Bottom Lining System Geomembrane

To eliminate the issues above, engineers weld the final cover geomembrane to the bottom lining system geomembrane for cases when there is a bottom lining system below the waste. The welding completely seals the landfill interior space from the outside environment and keeps regulated materials, such as waste, leachate, and gas, within the sealed system. Of course, the engineer should design proper means to address these behind the sealed system; designs may include:

  • A leachate toe drain system below the final cover geomembrane at the bottom of the landfill slope to collect and convey leachate seep liquids to the leachate collection system at the bottom of the landfill.
  • A suitable landfill gas collection system below the final cover geomembrane, at the lower boundary of the landfill slope, collects gases accumulating in the area.
    • This is an important consideration because the closest gas collection well may be over 250 ft. away, up on the slope.
  • A rainwater toe drain system above the final cover geomembrane, at the bottom of the landfill slope, collects and drains the water in the final cover geocomposite.

 

Leachate Toe Drain System (LTDS)

Leachate toe drain system is a concept originally developed by SCS and incorporated into landfill final cover designs over the past 20 years. Unfortunately, many solid waste engineers are unaware of the need for LTDS, so their designs lack this important feature. LTDS saves a tremendous amount of repair money in the long run by avoiding complications for landfill operators.

 

Rainwater Toe Drain System (RTDS)

A rainwater toe drain system removes water that moves laterally within the final cover geocomposite toward the slope’s bottom. The RTDS includes a perforated HDPE pipe encased in gravel and wrapped in geotextile. Also, install the RTDS on terraces along the depression on the interior side of the terrace. Along the landfill slope’s bottom, position the RTDS behind a HDPE flap welded to the final cover geomembrane. The RTDS is sloping with high and low points along the RTDS alignment. Lateral drain pipes located at low points remove water from the RTDS to the perimeter ditches.

Other designs involving extending the geocomposite to daylight at the slope surface cause problem such as those listed below:

  • Excessive vegetation impacts the opening of the geocomposite at the outlet edge.
  • Soil erosion from higher-ups clogs the opening of the geocomposite at the outlet edge.
  • Algae grow at the opening of the geocomposite at the outlet edge.
  • Gradual discharge of water from geocomposite softens the perimeter berm soils in the vicinity of the outlet edge.
  • Water percolates into the landfill perimeter berm and causes stability issues; and
  • A slippery surface develops along the outlet edge on top of the landfill perimeter berm, creating a health and safety issue for landfill personnel.

Similar issues can also occur at the outlet of such systems on landfill terraces, making the RTDS a superior design.

Landfill owners who are aware of the associated features mandate their inclusion to ensure their landfill final covers’ long-term superior performance.

 

About the Author:

Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering.

 

 

 

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

Advice from the Field: Knowledge of Landfill Sites and Efficacy of Conducting Due Diligence

December 21, 2020

web version

It is not out of the ordinary to see several different landfill designers providing services at a specific site over many years. Each landfill designer brings his/her preferences and designs to the owner, depending on the urgency of the projects and the owner’s willingness to accept new concepts.

Experienced landfill designers review the prior history of design work at the facility and ensure that their new design work is compatible with previously developed cells and final covers. Lack of such due diligence could impede landfilling operations following implementation of the design with implications that may survive for many years to come at a high cost to the owner.

Proper due diligence may reveal issues that the owner may not be aware of. In such cases, the new landfill engineer attempts to explain the observed issues from a previous design to the owner’s attention during one or more meetings or through a narrative report including documentation of the issues and measures to address each issue. The owner may accept or reject the technical matters brought to their attention by the new landfill designer. If accepted, authorize the new design engineer to prepare proper plans and details, and assist in retaining a contractor to fix noted problems. If rejected, the new landfill engineer can feel confident he/she is professionally conducting himself/herself considering the ethical obligations in his/her profession.

If the new landfill engineer had not brought up issues discovered during the due diligence, the owner could blame the new designer claiming that he/she should have known better. Such situations do not get resolved easily and could lead to another change in the design team.

The cost of performing thorough due diligence may not be in the first task order’s budget. However, it will certainly pay off over time with back-to-back task orders from the owner when confidence n the designer’s capabilities build over time.

Changes to the landfill personnel may occur similar to any other organization. Landfill general managers, operation managers, site engineers, or compliance engineers may leave, and the position filled by a new person who has no site familiarity or history. These types of rotations can provide the opportunity for inexperienced landfill designers to influence the site’s long-term plans. Mistakes by inexperienced designers can last decades in some instances, while new and remaining personnel must deal with the consequences.

SCS’s project management protocols require project managers to constantly learn about the site’s history and review documents representing the backbone of the facility development over the long-term life of the site to the present. This type of continual learning of important matters and minute nuances of the site history equips a project manager to address technical and permitting issues based on knowledge of prior work performed at the facility. Implementation of new ideas based on prior knowledge of the site history is considered the backbone of properly managing projects and serving the client in consideration of their business priorities.

Past knowledge comes from documents prepared by prior designers and knowledge of site personnel who have been working at the site for a long time. Competent engineers welcome opportunities to interview and discuss site history, especially with long-term site personnel. The knowledge these people carry with them is not found in any document that the designer, if lucky enough to get his/her hands-on, may obtain by review. The knowledge of the changes to existing systems during original construction and a later date, which may not have been documented, can lead the engineer to concepts that otherwise would not have been envisioned without the long-term employee’s information of the site.

As a landfill designer, never assume that you know everything about the site; there are always things hiding deep in the landfill that you may learn.

 

About the Author:

Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering.

 

 

 

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

On-Demand – Built to Last: Design, Build and Operate Landfills for Extreme Weather Resiliency

December 1, 2020

Each U.S. region faces unique weather and climate events. Solid waste facilities and landfills are particularly vulnerable to extreme weather since they are exposed 24/7 to the environment. Extreme weather can disrupt safe and cost-effective operations, increase maintenance needs, and may compromise landfill stability.

View the recording of this SCS Engineers’ November live webinar to learn how to increase your facility’s longevity and ability to survive extreme weather. The recording includes Q&A from solid waste professionals.

Our panelists,  Robert Gardner and Bob Isenberg, bring decades of expertise to the table, including landfill design and solid waste master planning. They provide strategies and resources based on successful solutions that help support your facility as you prepare for and likely will experience severe weather disruptions.

View Now in the SCS Learning Center

 

This educational webinar will help you:

  • Predict the impact of extreme weather on facilities and operational costs
  • Avoid costly repairs and environmental risks with planning and preparation
  • Continue to provide services to customers
  • Remain responsive to constituents’ concerns
  • Share and learn ideas and strategies among their peers without a sales pitch.

 

 

 

 

 

Posted by Diane Samuels at 12:00 am

SCS Advice from the Field: Standard Coordinate Systems for Landfill Topographic Maps

November 30, 2020

graphic by Samuels of SCS Engineers

Landfill engineers rely heavily on topographic maps in their design work. Topographic maps present elevation contours, known as contour lines, for changes in the ground surface. Surveying companies create contour lines by performing land surveys, Light Detection and Ranging (Lidar) surveys, or aerial mapping. In all cases, the topographic maps are generated based on a standard coordinate system.

Basing horizontal systems on geodetic coordinates worldwide, they may be updated every few years or decades. An example of the horizontal coordinate system is the North American Datum (NAD). A datum is a formal description of the Earth’s shape and an anchor point for the coordinate system. Using the NAD system, engineers can make horizontal measurements in consideration of the anchor point information.

NAD 27 and NAD 83 are two versions of the NAD system with slightly different assumptions and measurements. A point with specific latitude and longitude in NAD 27 Datum may be tens of feet away from a point with similar latitude and longitude in NAD 83 Datum.

The latitude and longitude of an initial point (Meads Ranch Triangulation Station in Kansas) define the NAD 27 Datum. The direction of a line between this point and a specified second point and two dimensions define the spheroid. Conversely, NAD 83 Datum uses a newer defined spheroid, the Geodetic Reference System of 1980 (GRS 80). GRS 80 is an Earth-centered or geocentric datum having no initial point or initial direction.

Similarly, vertical systems provide surveyors the means to measure vertical measurements based on a standard system. Examples of the vertical datum are the National Geodetic Vertical Datum 1929 (NGVD 29) and North American Vertical Datum 1988 (NAVD 88).

Using topographic maps, solid waste engineers pay special attention to the standard coordinate system used for generating the topographic map made available to them for their design work. Engineers will want to check for additional topographic maps using another Datum for the same site. Checking eliminates the possibility of discrepancies in the design documents.

Typically, the standard system set for a landfill site remains unchanged for consistency among topographic maps generated over the years. If the standard system must change, document the conversion making it available to the solid waste engineers working at the site. The conversion information is valuable for converting engineering plans to prevent the older plans from becoming obsolete and unusable for practical engineering work.

A solid waste engineer that begins work for the first time at an existing landfill site pays special attention to the standard system (horizontal or vertical). The engineer wants to ensure the time spent producing design documents and plans aren’t wasted. For optimum efficiency, landfill owners contracting with new solid waste engineers should provide conversion information from the old to the new system upon the contract’s commencement.

The United States National Spatial Reference System NAD 83(2011/MA11/PA11) epoch 2010.00, is a refinement of the NAD 83 datum using data from a network of very accurate GPS receivers at Continuously Operating Reference Stations (CORS). A new Global Navigation Satellite System (GNSS) will replace the National Spatial Reference System NAD 83 and the NAVD 88 in 2022, according to the National Geodetic Survey Strategic Plan 2019-2023. The GNSS will rely on the global positioning system and a gravimetric geoid model resulting from the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. The new systems’ intention is easier access and maintenance than NAD 83 and NAVD 88, which rely on physical survey targets that deteriorate over time.

Solid waste engineers should be aware of the upcoming changes to adapt site designs as necessary and to check with landfill owners and operators to check for any implementations at their facilities.


 

About the Authors:

Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering. Dr. Khatami has been involved for more than 30 years in the design and permitting of civil/solid waste/environmental projects such as surface water management systems, drainage structures, municipal solid waste landfills, hazardous solid waste landfills, low-level radioactive waste landfills, leachate and wastewater conveyance and treatment systems, gas management systems, hazardous waste impoundments, storage tank systems, waste tire processing facilities, composting facilities, material recovery facilities, landfill gas collection and disposal systems, leachate evaporator systems, and liquid impoundment floating covers. Dr. Khatami has acquired extensive experience and knowledge in the areas of geology, hydrogeology, hydrology, hydraulics, construction methods, material science, construction quality assurance (CQA), and stability of earth systems. Dr. Khatami has applied this experience in the siting of numerous landfills.

William Richardson, EIT is Project Professional at SCS, and part of our Young Professionals organization. Will has two years of experience with landfill design projects, including permit modifications and siting requirements. He is currently working in Virginia Beach under the tutelage of Dr. Khatami.

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

SCS Advice from the Field: Familiarization with Site History before Design Work for Landfills

November 23, 2020

Landfills are large and dynamic systems that can take several decades to develop. Unlike many other infrastructure projects that have a beginning and an end to the construction of the project, landfills constantly grow and change due to many factors, including but not limited to:

  • The type of waste stream delivered to the site;
  • Type of operations carried on at the site;
  • Operator’s experience and operational preferences;
  • Capital flow into the site;
  • State and local regulatory changes;
  • Engineer’s recommendations;
  • The rate of development around the site;
  • Interactions with local communities around the site;
  • Agreements with environmental groups; and
  • Political will and the extent of support by politicians.

From an engineering perspective, it is very common to see changes to the engineering team over time. Each team brings about their ideas and preferences to the operator, and if they present technically competent and economically solid ideas, they can change the course of the landfill development. The course change could be shaped by what will get constructed, how it will get constructed, when it will get constructed, and what sequence it will get constructed. In most cases, the owner is in the loop, but the owner may not be intimately familiar with the nuances that such designs and modifications entail. Therefore, the owner may not necessarily realize hidden problems or mishaps that may happen in the future, which could be prevented by the engineer at an earlier stage of work.

Competent engineers starting work at an existing landfill site for the first time need to review years of data to become familiar with the history of the site before they can begin design work. The history of the site involves, but is not limited to, land use approvals, permitting, designs, modifications, environmental impacts, subsurface conditions, environmental improvements, leachate and gas collection and disposal, existing and future planned developments, operation requirements, and many other features that vary from site to site. Without such knowledge, the engineer is working in the dark without the owner’s knowledge that the engineer’s path lacks familiarity with details. Work products generated by an engineer with limited familiarity with the site are, at best, not reliable. Even potentially having significant impacts on the owner to fix issues that otherwise are preventable with sufficient due diligence.

For example, tasking an engineer to close a portion of the landfill, the engineer must investigate any plans set for landfill development, in the area planned to close. The engineer and owner can discuss any problems discovered by the engineer’s early due diligence, and solutions will be developed and adopted to address issues during the design. This level of due diligence provides the opportunity to generate sound designs and develops a level of confidence in the engineer in the mind of the owner.

SCS landfill design professionals train regularly to be thorough and comprehensive in their familiarization with a site. They spend significant effort to foresee potential problems that might arise many years down the road and find solutions for them now.


 

About the Authors:

Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering. Dr. Khatami has been involved for more than 30 years in the design and permitting of civil/solid waste/environmental projects such as surface water management systems, drainage structures, municipal solid waste landfills, hazardous solid waste landfills, low-level radioactive waste landfills, leachate and wastewater conveyance and treatment systems, gas management systems, hazardous waste impoundments, storage tank systems, waste tire processing facilities, composting facilities, material recovery facilities, landfill gas collection and disposal systems, leachate evaporator systems, and liquid impoundment floating covers. Dr. Khatami has acquired extensive experience and knowledge in the areas of geology, hydrogeology, hydrology, hydraulics, construction methods, material science, construction quality assurance (CQA), and stability of earth systems. Dr. Khatami has applied this experience in the siting of numerous landfills.

William Richardson, EIT is Project Professional at SCS, and part of our Young Professionals organization. Will has two years of experience with landfill design projects, including permit modifications and siting requirements. He is currently working in Virginia Beach under the tutelage of Dr. Khatami.

 

 

 

Posted by Diane Samuels at 6:00 am

SCS Advice from the Field: Long Term Performance of Landfill Final Covers

November 16, 2020

landfill closure
With the proper design and planning, partial final covers can provide multiple benefits and long-term performance from the active life and well beyond.

About the Author: Ali Khatami, Ph.D., P.E.

There are several hundreds of Municipal Solid Waste (MSW) landfills in the United States. Many of these landfills are anticipated to remain active for decades to come, and Federal and state rules require slopes reaching permitted final elevations to be closed within 180 days. This means partial closure of slopes is part of the operational requirements of MSW landfills.

Federal and State Rules

Subtitle D of the Resource Conservation and Recovery Act (RCRA), enacted on October 21, 1976, requires the final cover of MSW landfills to include a barrier layer with hydraulic conductivity that is substantially equivalent to or less than the hydraulic conductivity of the bottom liner. State-level regulations developed following the enactment of the federal law also required similar standards for MSW landfills. Many states, pursuing the federal guidelines, require at a minimum, the bottom lining system of MSW landfills include at least one primary barrier layer consisting of Polyvinyl chloride (PVC), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE). Naturally, the final cover barrier layer should also be PVC, HDPE, LLDPE as well.

According to the Federal and state regulations, following the completion and closure of a MSW landfill, the facility owner maintains the landfill for a minimum of 30 years beyond the final closing date. Extension of the long-term care period beyond the 30-year post-closure period is a hot subject among solid waste professionals. Some states have already implemented matrices for such time extensions; it is anticipated that the remaining states will require similar extensions for MSW landfills over the next several years. Even if regulatory agencies approve completion of the post-closure period for a specific landfill, the landfill’s final cover system is expected to perform for many more years to come. Otherwise, environmental issues associated with a lack of performance may force the regulatory agency to spend money for repairs no longer available through a financial instrument.

Long-Term Performance Designs

For the past few decades, SCS has specifically designed and permitted final cover systems with special features to prolong the final cover system’s performance beyond the post-closure period of the landfill. The final cover system designs:

  • Maximize available airspace in the landfill,
  • Simplify waste placement in the vicinity of the exterior landfill slopes,
  • Simplify stormwater management components over landfill slopes,
  • Effectively collect and remove rainwater percolating through the final cover soils,
  • Collect lateral leachate seeps below the final cover barrier layer, and
  • Effectively encapsulate landfill gas at the landfill perimeter.

Less Maintenance

The first partial final cover with these features was constructed in 1998, and since then, many more partial closures with these types of features have been constructed. All partial closures are performing satisfactorily without failure. Regular maintenance of the final cover vegetation and occasional cleaning of drainage swales, which are common maintenance activities, have been the only measures taken by the operators of the facilities with these final cover systems.

The features incorporated into the final cover systems were:

  • Straight 3H:1V slopes to the top of the landfill with no benches or terraces, providing benefits such as maximizing airspace; eliminating complications during filling of the landfill near exterior slopes; allowing final surface water drainage swales to be constructed during the construction of the final cover which provides flexibility for the swale locations, swale slopes, drainage points of swales on the slopes; and downchute pipes that do not require complicated geometric features at the point of connection to drainage swales on the slope;
  • A leachate toe drain system (LTDS) collecting and disposing of leachate seeps below the final cover geomembrane reaching the bottom of the landfill slope; and
  • A rainwater toe drain system (RTDS) collecting and draining out of the final cover the rainwater that percolates through the final cover reaching the cover system geocomposite drainage layer.

The features above have financial, performance, and stability benefits for the facility for many years to come. So far, such final covers have been constructed on 3H:1V slopes as long as 550 ft. in length with no terraces. Several of the completed final covers were partial closures on a 3H:1V slope, where the next phase was constructed directly above a previous phase with the two phases tied together at the phase boundary.

Proper design and planning for the construction of partial final covers are significantly important for the long-term performance of landfills during the active life, post-closure period, and beyond.

 


 

Want more advice from our designers? Select articles and blogs for further reading:

 

 

 

 

 

Posted by Diane Samuels at 6:00 am

Elevated Temperature Conditions in Landfills: Sharing Innovative Designs and Strategies

July 20, 2020

The large majority of landfills in the country show no signs of special conditions indicating too much heat. Under certain conditions, elevated temperatures may occur inside a landfill, and the excess heat changes the character of chemical reactions taking place in the landfill, such as the decomposition process of the organic matter. Read and follow SCS Advice from the Field blogs for landfill best management practices.

 

SCS Advice from the Field

Landfill operators have known about elevated temperature conditions in landfills for nearly a decade. Some operators have already incurred numerous expenses to control adverse environmental and operational issues at these landfills, and some operators have set aside large amounts of money in their books to address future liabilities associated with such landfills. Due to the complexities of controlling elevated temperature conditions and the compliance issues arising from such conditions, it can force operators to temporarily, or permanently close their landfills.

Can design address elevated temperature conditions?

The operators of larger landfills have been monitoring and analyzing data to identify triggering factors, while others continue controlling the environmental impacts. Environmental Research & Education Foundation (EREF) initiated several research projects to identify the triggering factors with the excellent scientific work of highly qualified researchers. These are on-going projects.

In the meanwhile, operators of larger landfills are developing strategies, basing strategic-decisions on the data and conditions collected during operations over long periods. After analyses, they have the means to reduce the impacts by making changes in their operations and landfill designs. The most effective changes include eliminating certain waste types from the waste stream and improving the movement of liquid and gas through the waste column with new designs.

Are design innovations consistently implemented?

The pioneering designs feature preventative measures, intending to avert the formation of elevated temperature conditions in future disposal cells. Implementing these new design features requires careful consideration and functional analyses, as some of the recommendations can be costly, affecting the bottom line. The urgency in controlling compliance issues associated with elevated temperatures and the associated financial impacts of such conditions objectively prescribe that local managers work closely with their designers and field expertise to bring non-compliance issues under control.

Is this an executive risk management strategy?

Until the on-going research more clearly identifies the triggering factors and the means to prevent the development of elevated temperature conditions, it seems logical to invest in implementing preventative measures that are currently available. When more research results are accessible, then the local managers will be able to make decisions that are even more informed. Those wanting to address the likelihood of future liabilities proactively will need executive-level funding and superior technical support, all of which are possible.

Is there much sharing of newer designs and strategies within the solid waste industry?

Yes, there is a fair amount of collaboration among the technical community and within solid waste associations. Most operators share their preventative designs within the engineering community and help contribute to funded research. Their actions and results will help to strengthen an industry application until such time that research results and the means to prevent the development of elevated temperature conditions are well understood. We all know that progress in technology and science depends on sharing new knowledge.

Let’s continue with the combination of serious research, innovative designs, proactive operational changes, and sharing knowledge among our industry professionals that will lead to more precise solutions in the near future. Here are a few resources available now:

 


 

About the Author:  Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Elevated Temperature Landfills, plus Landfill Design and Construction Quality Assurance. He has nearly 40 years of research and professional experience in mechanical, structural, and civil engineering.

Learn more at Elevated Temperature Landfills 

 

 

 

 

 

Posted by Diane Samuels at 6:00 am