It is a general misconception that leachate seeps stop or disappear when slopes receive the final cover. In fact, it is only true if the source of leachate is located directly below the cover, but in most cases, the leachate originates from another location. Continuing seeps eventually reach the bottom of the slope, where two scenarios can happen depending on how the final cover geomembrane is secured at the landfill’s perimeter.
In the first scenario, where the geomembrane is anchored in an anchor trench, liquids will gradually flow underneath the cover geomembrane in the anchor trench and enter the perimeter berm structure. Leachate entering the berm structure softens the berm’s structural fill adversely impacting its shear strength. Additionally, leachate gradually seeps through the berm structure and enters natural formations below the berm and possibly into the groundwater. The operator is alerted when monitoring shows a localized structural failure or a groundwater impact in a nearby groundwater monitoring well.
In the second scenario, where the final cover geomembrane is welded to the bottom lining system geomembrane, leachate seeping out of the slope reaching the toe of the slope accumulates at the toe because it has nowhere to go. Accumulation of leachate behind the final cover geomembrane forces water to gradually move laterally along the landfill perimeter berm behind the final cover geomembrane damaging a larger area behind the final cover. Vertically, more of the area above the toe of the slope becomes engaged by the accumulating leachate. The two obvious consequences are the softening of the soil layer below the final cover geomembrane at the toe of the slope and the water-bedding effect of the area near the toe of the slope.
In the first scenario, the operator has to handle a non-compliance issue, either a failure in the slope or impacts to groundwater. In the second case, the leachate remains contained, but the operator has to address the issue by opening the final cover and removing leachate accumulated behind the final cover geomembrane. The geomembrane opening is closed, and final cover soils are restored after liquids are removed. Both are costly and complicated solutions. Moreover, the problem does not end after completion of the repair because the source of leachate seep is not eliminated.
Landfill operators can require their engineers to design a leachate toe drain system located at the toe of the slope and connected to the leachate collection system at the bottom of the landfill before the final cover geomembrane is installed. The leachate toe drain system is the only way to collect and route leachate to a location at the bottom of the landfill constructed for removal of leachate.
If you are closing a portion of your landfill slope and you find no leachate toe drain system in the construction plans, you can ask for a system to be added to the design plans before the commencement of the construction project.
SCS has significant experience with various types of leachate toe drain system constructed at different locations under various conditions. If you like to know more about the design of leachate toe drain systems or if you are looking for an experienced engineer for the design of your next final cover contact SCS.
Author: Dr. Ali Khatami
SCS Engineers periodically prepares Technical Bulletins to highlight items of interest to our clients and friends. Our most recent SCS Bulletin summarizes the Brownfields BUILD Act (Brownfields Utilization, Investment, and Local Development). The BUILD Act was signed into law in March 2018, amending the Brownfields provisions of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Specific changes include increased eligibility for funding, additional liability protections, and changes to grant programs. The link above will take you directly to the summary.
SCS will continually update coverage of this Act on our website. I welcome you to use our staff resources for guidance or to answer questions.
SCS Engineers periodically prepares Technical Bulletins to highlight items of interest to our clients and friends. Our most recent SCS Bulletin summarizes the amendments addressing the updates to the Final Coal Combustion Residuals (CCR) Rule that the EPA published in the Federal Register on July 30, 2018, and which takes effect on August 29, 2018. The link above will take you directly to the summary.
SCS will continually update coverage of this Rule on our website. We welcome you to use our staff resources for guidance or to answer questions.
Landfill base grades not only make leachate collection and removal possible but also have a significant impact on the amount of landfill airspace. For landfill operators, airspace is the primary asset, because it represents the level of revenue the operator can expect. Airspace is a commodity to be maximized.
Operators expect to get the most airspace from their landfill designer and depend on the engineer to design the grades to maximize it. Placing your trust in an engineer is a noble matter, but as the operator, you check, verify, and confirm that what the designer has engineered is what is needed to provide you with the expected value. An experienced landfill designer looks for ways to provide airspace above and beyond the operator’s expectations.
SCS has been in the business of designing landfills for nearly half a century. We have significant experience in optimizing landfill designs and maximizing airspace. SCS is often retained to design a new expansion to an existing landfill. Upon starting work we analyze the entire facility holistically to see all of the potential ways to maximize airspace around and above the existing landfill. Every cubic yard of additional airspace is a big achievement for our clients and in turn for us.
SCS often evaluates permitted, yet to be developed, base grades for operators. The intent is to determine whether additional airspace can be achieved by applying a different design to the base of the landfill. SCS has turned the science of geometry into mathematical models utilized to quickly evaluate base grades. Specific parameters of the currently permitted base grades are plugged in the mathematical model along with those of the alternative and the model provides quantitative values (cubic yards) of the difference between the permitted grades and the alternative. The values are quickly returned. After modeling, the operator may decide to modify the design to gain the additional airspace based on the alternative design. Contact us to work with our landfill design experts to assist you with an evaluation.
Contact Dr. Ali Khatami with questions about the model.
The Georgia Manufacturing Alliance (GMA), based in Lawrenceville, GA, is a professional organization founded in 2008 to support Georgia’s manufacturing community. SCS Engineers is pleased to announce the firm is GMA’s newest member supporting manufacturers with permitting, compliance, and other environmental services.
Mike Fisher, SCS’s point of contact, has three decades of experience supporting environmental consulting for manufacturers and other industries throughout Florida, North Carolina, South Carolina, Georgia, Alabama, the Bahamas, and South America. Mike has deep well petroleum geology expertise dating nearly four decades.
Learn more about each of our manufacturing solutions areas by clicking on the links below:
SCS Young Professional, Hydrogeologist Nicole Kron, recently finished her second session of Skype a Scientist, a program in which she Skypes with classrooms and talks to kids about her work as a professional geologist and her journey to become a scientist. The Skype a Scientist program connects students and teachers with people in scientific jobs to help attract kids to science, technology, engineering, and math (STEM) pursuits.
Skype a Scientist matches scientists with classrooms around the world; teachers are able to choose the type of scientist that will match their classroom’s interests. Participating scientists, like Nicole, then skype with the students for 30 to 60 minute Q&A sessions that can cover any topic – from their particular expertise to what it’s like to work as a scientist to their favorite pastimes. The program helps students get to know a “real scientist” and about their career in a STEM arena.
Nicole has completed two sessions so far – one in May and one in June, and she has agreed to stay involved with the program going forward. “It’s so much fun!” she says.
Some of the questions Nicole has answered include:
During these sessions, Nicole talked about geology, work-life balance, self-confidence, and her hobbies. The ninth grade class was particularly interested in her new venture to make French macarons as well as her love of dancing.
Nicole says she really enjoys participating in Skype a Scientist because, “It gives
me the opportunity to show students that scientists and engineers are well-rounded
people with many interests.”
An SCS Marketing Manager, Sarah Hoke, added: “I love to see our folks making an impact in the community.”
It’s never too soon to start recruiting the scientists of the future!
Nicole and Sarah both work at SCS Engineers in the Madison, Wisconsin office. SCS Engineers provides career opportunities across the nation to talented individuals who bring value to their clients and in their communities.
In an increasingly complex regulatory world, Remote Monitoring and Control (RMC) systems provide the tools necessary to improve safety, increase efficiency and make the right decisions quickly. Beyond capturing and storing data, these systems can sort through mountains of data, identify what’s important and deliver meaningful information to operators in real time or as needed.
Some of the added benefits of using RMC systems include:
Read the Waste Today article – click here. Learn more about Remote Monitoring and Control here.
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.
On April 9, 2018, the U.S. Department of Treasury and the IRS approved Opportunity Zones for: American Samoa; Arizona; California; Colorado; Georgia; Idaho; Kentucky; Michigan; Mississippi; Nebraska; New Jersey; Oklahoma; Puerto Rico; South Carolina; South Dakota; Vermont; Virgin Islands; and Wisconsin. The Treasury Department has made the final designations of Opportunity Zones in more states during June 2018.
Use this interactive map to locate eligible zones in your state.
Opportunity Zones are communities where new investments may be eligible for significant tax incentives. The zones are based on Census Tracts that meet income criteria, and were created in the federal Tax Cuts and Jobs Act of 2017 as a means of helping economically depressed areas through tax incentives for new private investments.
Investors can defer tax on prior gains invested in a Qualified Opportunity Fund (a fund set up to make investments in Qualified Opportunity Zones). In addition, if investors hold the investment in the Opportunity Fund for at least five years they are eligible for capital gains tax reductions or exemptions. If they hold the investment in the Opportunity Fund for at least ten years, they are eligible for an increase in its basis equal to the fair market value of the investment on the date that it is sold.
Brownfields and Opportunity Zones
Many of the communities in the Opportunity Zones have properties impacted by environmental contamination. The Opportunity Zones program provides an economic tool to attract developers and financial backing to communities with brownfield redevelopment needs.
If you are interested in investing in a potential brownfield site, contact SCS Engineers to help you evaluate and manage environmental concerns associated with your site. Visit www.scsengineers.com to learn more.
This paper, presented at A&WMA’s 111th Annual Conference details the Tier 4 process and the potential issues that have arisen from conducting a Tier 4. This paper also assesses potential Tier 4 sites, exceedance reporting, wind monitoring, additional SEM equipment requirements, penetration monitoring, notification and reporting requirements, and impacts on solid waste landfills that will use the Tier 4 SEM procedure for delaying GCCS requirements. This paper reviews the changes between the draft NSPS and the final version of the new NSPS that was promulgated.
Click to read or share the paper, and learn about the authors.
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