The Iowa Recycling and Solid Waste Management Conference planning committee is diligently working on hosting an in-person conference October 4-6, 2021, at the DoubleTree by Hilton Hotel Cedar Rapids Convention Complex. Naturally, we’ll be attending if at all possible. So get your vaccine and plan to head to Cedar Rapids in October.
Check back; more information to come! We are recycling it here 🙂
Join SCS Engineers for our 28th Annual Virginia Landfill & Solid Waste Seminar, which will be held virtually, on April 21, from 9:00 am to 1:00 pm Eastern.
This year’s seminar will cover the following topics:
Evaporation as a Leachate Management Tool – 2 Case Studies, with David Greene, PE, SCS Project Manager
Virginia Regulatory Update, with Priscilla Rohrer, Solid Waste Compliance Coordinator, Virginia Department of Environmental Quality (VDEQ)
Solar Opportunities on Closed Landfills, with Dana Blumberg, PE, BCEE, SCS Vice President
Solid Waste Facility Design: How to Get Started, with Mike Kalish, PE, LEED AP, SCS Vice President
Landfill Odor Mitigation, Abatement, and Control Case Studies, with Bob Dick, PE, BCEE, SCS Vice President
This half-day seminar is designed to provide updates on the latest regulatory, policy, and technological developments in solid waste, landfill and landfill gas industries.
The seminar is intended for solid waste management professionals, landfill managers, waste/recycling managers, supervisors, and operators. For attendees already possessing landfill experience, topics will provide a fresh perspective and cover important regulatory and technological updates. For those new to the field, topics will cover essential information on all aspects of landfill development, operations, monitoring, and management.
Advanced Registration is Required. Click to view Brochure and to Register
Managing oil and gas waste is challenging, even when practicing due diligence. The job requires impeccable skill and attention and sometimes outside support, which Colorado operators recently learned when they found high oil content in leachate coming out of their sump. They turned to SCS, knowing through their longstanding relationship with the engineers and that their liquids management team could deal with oil-laden wastewater.
Ensuring sustainable outcomes begins with collecting and analyzing comprehensive data that become the building blocks for a feasibility study. The study helps with immediate challenges and builds a more holistic approach to tackle increasingly expensive operation challenges at landfills.
“First, we talk about the site’s leachate history, including quality and quantity. What is the source of the waste generating the leachate, and where is it deposited? How are liquids used in current operations? The current practice used the liquids on the landfill surface for dust control, leaving an unsightly oily sheen.
Once we talk about how the site currently manages these liquids, we discuss options for future handling for improvement,” says Neil Nowak, SCS Engineers project director. “You’ve got to have a holistic understanding of day-to-day operations with the data to solve the problem cost-effectively.”
Neil’s preliminary research led to one recommendation to meet all the criteria – separate oil and water from leachate as the liquid exits the pump. The separation process can reduce the oil-laden leachate volume by 70 percent.
The technology works by separating the leachate into oil and water portions using an oil/water separator, such as a gun barrel tank, which is low cost and effective. After piping the water to an evaporation pond, the collected oil is sent offsite for future handling, usually disposal.
“This method gives the operator a better option for dealing with the leachate over the current practice of spraying it on the landfill surface for dust control,” Nowak says.
Spraying usually provides an alternative for liquids while reducing disposal time and cost. However, he explains, oil-laden leachate is a different beast than typical MSW liquids and calls for a more creative solution to remain within regulatory compliance.
Oil and water separation eliminates the aesthetics issues at the site with its previous practice. The greater value is that this method gives operators full control of oil’s movement, which can otherwise be very hard to accomplish.
“Oily leachate can adhere to the wheels of equipment that move dirt over the landfill surface; consequently, it ends up in places operators do not want it to go. Oil and water separation technology is a reliable way to keep it out of surface drainage areas and ensure it does not infiltrate into groundwater outside of the lined space,” Nowak explains.
Operators avoid short- and long-term consequences springing from compliance issues, but beyond today, the technology that SCS sizes operates for 20-plus years and helps prepare them for the long haul.
This option enables waste pros who take on growing demand from the oil and gas industry to protect the environment and public health, even as volumes increase. Oily liquids are particularly challenging for wastewater plants. Separation technology provides greater assurance that the landfill will still have a home for their leachate as wastewater treatment plants raise the bar on what they will allow.
The remaining question…
What is the most cost-effective and safe way to eliminate the filtered oil?
The solution for the immediate need is straightforward and simple. Depending on geology, local regulatory policy, and cost factors, solidification or injection are the most common, safe practices now, but reuse options are under development. Reuse and prevention are part of a longer-term landfill strategy, so Neil draws on his colleagues’ expertise.
Nowak’s expertise comes from years of experience supporting the oil and gas industry. Backing him is national liquid management expert Nathan Hamm, who lends technical expertise and insight on best practices for reducing leachate.
Commonly the best bang for your leachate management dollar is to reduce the volume of leachate or wastewater to treat in the first place. Operators can begin by diverting stormwater away from active portions of the landfill, then installing a better cover system. Depending on the landfill’s need and location, reducing the size of new cells and timing those new cells to come online during low precipitation seasons is practical. Leachate minimization practices such as these directly reduce the treatment system capital and ongoing operational costs.
The Colorado operator now has oil and gas waste management options and has a comprehensive, site-specific review of leachate management with a clear understanding of where there is room for improvement.
As far as their immediate priorities, says Nowak, “We have left them with enough thought-out information to make informed decisions, and for now, they are leaning toward the oil and water separation technology. Though they can keep operating without it, they are looking to get ahead of possible compliance issues by making changes voluntarily, which are usually less costly in the end and demonstrates social responsibility to the Colorado Department of Public Health and Environment and the EPA.
Not too long ago, SCSer Gomathy Radhakrishna Iyer thought she’d become a mechanical engineer but decided to go down another path at her father’s coaxing, and she’s never looked back. Today she is a Civil & Environmental Engineering Ph.D. and has become deeply entrenched in the world of landfills—human-made formations that she calls “beautiful.”
Dr. Iyer’s work spans research and engineering projects in landfill gas emissions reduction, landfill design, and leachate management. She’s also keeping up with PFAS to be ready for what may lie ahead around these emerging contaminants. “What I’m most into these days is researching and helping clients select leachate treatment systems and doing landfill expansion designs. It’s so mentally rewarding when you find solutions for the client’s problems. They are happy, and you are happy,” says the SCS staff professional.
She is known by more than her work family. Gomathy is a published researcher and speaker, most recently presenting at the Global Waste Management Symposium in February 2020. Her presentation covered one of her pet topics, her Ph.D. focus: using grass clippings and biosolids as biocovers to remove methane from landfills.
Pre-COVID, she spent many of her days in the field. Lately, she spends a little more time anchored to her computer in her home office. There she typically works on a few spreadsheets at a time, maybe as part of a gas emissions report, a stability analysis, or settlement analysis. Then she shifts her focus to her design drawings. Dr. Iyer still manages to break away to put on her PPE – her hardhat, safety vest, and steel-toed boots. She happily drives off in a company truck to the landfill, lugging field parameter testing probes and a 10-pound ISCO to collect leachate samples; or do other fieldwork like locating LFG wells and pipes or other features that help her design.
In the summers, it gets scorching hot. And the winters can be bone-chilling cold, especially for a woman who spent most of her life in India, where she was born and raised. In her last years there, she studied the transport of heavy metals through groundwater. Then, it was on to the University of Texas, Arlington, where she earned her Ph.D. and became set on finding work at SCS, coming on board in 2019.
Among her earliest challenges was communication. “Sometimes I would be in a meeting or having lunch with my colleagues, and they would bring up baseball or other games or a Netflix series. They were new concepts to me, and I couldn’t relate. While I speak English, I was unacquainted with the vernacular. I was like, what is Super Bowl? I thought maybe it was something very big that people eat from,” she recalls. That does not stop a researcher.
Finding a way to become better acclimated became a project of sorts. She started spending weekend downtime in front of the TV to learn about these American pastimes. Baseball still isn’t her first love, but she’s happy to say, “In 2019, I went to my first Washington Nationals game with a big group from SCS, and I had at least some knowledge of what was going on.”
The ambitious civil engineer has pushed past another on-the-job challenge—one brought on by the impulse to know every detail she can nail down before setting to work. “Since I’m from a research background, I tend to dig to the very bottom to try and know the problem completely. Sometimes it’s a good thing. But I’ve had to be conscious of time constraints, gain an understanding of the minimum required to do the job well, and move on,” she says.
What first brought her to the United States was her husband, Ramesh Padmanabhan. He was working on a Ph.D. at the University of Texas at Dallas while she was studying in India, so the relationship truly began as a long-distance one. They got to know each other through a combination of old-world traditions and 21st Century channels. “Ours was an arranged marriage. Our parents introduced us, and for the first year, we met up and talked on SKYPE,” Dr. Iyer recollects. He’s a molecular and cell biologist and sometimes her consultant too.
“In my job, I need to know the biology and chemistry of microbes as they are responsible for breaking down waste, and he is my encyclopedia. I don’t have to Google as much when he’s around.” She adds: “I can’t complete my story without talking about my brother who has given me unconditional support and career advising through my life. These two men are pillars of my life.”
As a woman civil engineer who’s all about waste, she’s in the minority, but she doesn’t feel as if she is because women are moving into waste engineering. She’s one of four women on an eight-person team, who she says is “like my family. And my supervisor is a great supporter of women in STEM (science technology, engineering, and math).”
She hears from many newly degreed civil engineers, including “young ladies” with questions about waste management. They read blogs about her work that originated on SCS’s website and are on social media. “These graduates want to take their career to the next level, and they have a lot of questions about how to start solving waste issues,” she says. She tells them that solid waste management is one of the best and most stable industries they can choose and that the pandemic has driven that point home. “We are reminded through COVID that waste management is an essential business, and there will always be jobs to support it,” she says.
What Dr. Iyer loves most about her job is what she and her team imagine and draft in drawings, keeps developing, and in time, is built. “It’s like giving birth to a baby. Very exciting,” she says. Her groundwater contamination remediation work got her interested in PFAS, even before she finished her studies. “I had a lab mate in school who did PFAS research. That got me curious about these emerging contaminants. I’ve stayed vigilant to keep up with what’s happening with regulations and treatment options under research. If regulations now under consideration are implemented, our clients will have to start thinking more proactively about addressing PFAS. So, we need to learn more on a holistic level about what these contaminants can do and the best way to treat them.”
She tells the story of how her venture into civil engineering started with her father. “He wanted to be a civil engineer himself but was the eighth son, so his parents couldn’t afford tuition, and in India, you don’t go to college once you are grown with a family,” she explains. He wanted his daughter, already drawn to engineering, to pursue what had been his dream and said he thought it would suit her better than the direction she was leaning. “Had I studied mechanical engineering as I’d been thinking of doing, I would not have come into waste.” She is happy with where she’s landed.
“When you work all day and still are not tired –you still enjoy it and are happy to contribute to something good—that’s how you know it’s the right fit.”
Lately, landfill operators are putting stock in onsite landfill leachate treatment systems as a strategy to stay on top of increasing requirements in their already demanding regulatory world. Leachate treatment systems help meet tightening restrictions on liquids that landfills send to municipal wastewater treatment plants or discharge directly. And onsite leachate treatment gives operators a leg up should they one day have to deal with any emerging contaminants found on an expanding list.
With their eyes on compliance, landfill owners and operators are looking to leachate treatment systems that can ease the impact of soaring leachate disposal costs. Of course, the more contamination, the harder the hit since higher contaminants can mean higher municipal treatment plant surcharges or the landfill having to haul its leachate longer distances to a treatment plant that will accept it. Both examples usually result in higher treatment, disposal, and hauling costs.
A spike in its ammonia concentrations was enough impetus for one Oregon landfill operator to turn to SCS Engineers a few months ago. At its highest levels, the ammonia climbed to 50-fold what many small wastewater treatment plants, like the one in the Northwest, will take over the long-term.
Project Director Shane Latimer and Technical Lead Sam Cooke got on the stick to figure out how their client could keep hauling and disposing of leachate at the local wastewater treatment plant it has routinely relied on for years.
Coming up with a plan is a complex, multi-step process that requires looking through many lenses. To design a cost-effective, efficient treatment facility, Latimer and Cooke use an in-house multidisciplinary team of co-workers from Project Management, Chemical Engineering, Civil Engineering, and Geotechnical Engineering. The team performs in-depth analyses to identify the most economical and feasible technology. A design that in this case not only addresses ammonia but prepares the operator for emerging contaminants, such as the possible need for per and polyfluoroalkyl substances (PFAS) reduction, which Cooke describes as a train that has not yet arrived in Oregon but has left the station and is heading down the track.
Starting with the most immediate concern, Cooke says, “Our client had seen ammonia concentrations between 500 and 1,500 mg per liter, which is high. Acceptable ammonia levels can vary depending on the type of facility and how much leachate they expect to get compared to their total flow. But small treatment plants like the one our client depends on will set ammonia limits of about 25 or 30 mg per liter,” he says.
SCS begins with a leachate pretreatment options analysis to dive into details beyond ammonia levels – spikes in ammonia call for close attention. Still, there’s more to consider in masterminding a robust and fitting plan to manage the complex process.
“These are biological treatment systems, and there is no one-size-fits-all answer. You need to know how these systems will react to whatever is in your leachate, so you have to account for more than ammonia, or whatever your constituents of concern are,” Latimer says.
SCS’s leachate contaminant analyses use the landfill’s historical data along with what they learn from tests that SCS orders to understand alkalinity, pH, and carbon, among other leachate chemistry puzzle pieces.
“We look at concentrations of raw leachate, flow rate, pretreatment requirements, and other factors. We want to get a comprehensive picture of the problem and ultimately make the best treatment decision to get compound concentrations down to acceptable discharge levels,” Latimer explains.
What customized solution did the team design for the client in Oregon? The system of choice is a membrane bioreactor (MBR), which combines membrane separation technology with traditional activated sludge technology with optional reverse osmosis treatment. The design is a compact, efficient, biological wastewater treatment plant.
“An MBR is an elegant solution. We found it to be a good choice for this application for several reasons. It takes up relatively little space and fits well within the available plant footprint. It produces a relatively low-volume waste sludge stream. And it can cost-effectively treat multiple constituents of concern, so should new leachate chemistry issues arise, an MBR can address many of them,” Cooke says.
Being able to handle multiple concerns if and when they arise is key here. Cooke and Latimer wanted not only to get the immediate problem in check but see that the client has a dynamic and robust system to tackle whatever new challenges may be down the road.
When SCS goes into design mode, they plan ahead by engineering modular systems to add additional treatment methods if and when they’re necessary.
“For instance, MBR treats the leachate to reduce ammonia, other nutrients, organics, and suspended solids. By leveraging this treatment method first, you eliminate a lot of the bulkier constituents. But we left room for a modular addition such as reverse osmosis for “polishing,” treating MBR discharge for other minor constituents including PFAS,” Cooke says.
The client who came to SCS for a relatively inexpensive remedy for an ammonia problem now has a feasible, economical asset for leachate management.
“These investments are good security for landfill operators,” says Latimer. “If a municipal wastewater treatment plant is struggling to meet its standards, eliminating one contributing source of wastewater, like a landfill, could potentially solve several issues, such as ammonia, biochemical oxygen demand, and total suspended solids.”
But these treatment systems provide added security for more than the landfill.
“When disposal sites invest in sound leachate treatment systems, it’s also good for municipal wastewater treatment plants. It assures them that landfill operators will help them with the overall regulatory burden. We are helping them both to prepare for present and future challenges,” says Latimer.
SCS Engineers’ Gomathy Radhakrishna Iyer explains, “The structure of PFAs is a carbon and fluorine bond, and that bond is considered one of the strongest in nature. For industry, Chlorofluorocarbons (CFC), a volatile derivative of methane, ethane, and propane, creates problems globally after they’ve been released. Chlorofluorocarbons are strong greenhouse gases and are also responsible for the destruction of stratospheric ozone.
The most publicized of these compounds are those used as coolants in refrigeration and air conditioners, as propellants in spray cans and similar products, and as solvents for industrial purposes. Chlorofluorocarbons are far less abundant than carbon dioxide in the atmosphere. Still, they are 10,000 times more potent as a greenhouse gas and can remain in the atmosphere for more than 45 to 100 years. Reference
Iyer continues, “PFAS has the same kind of carbon-fluorine bond as CFC but linked to several C-F bonds like a chain making them even more inert and hard to degrade. Breaking this bond is what makes finding effective leachate treatments challenging, but certainly possible.”
It takes a savvy engineer to design safe and effective systems. We’re very proud of our Young Professionals like Gomathy – they’re smart and continue learning with the guidance of our VEPs – very experienced professionals.
Open positions at SCS Engineers for YPs and VEPs
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
Landfills located in areas with high precipitation usually experience leachate seeps on slopes. The location of leachate seeps varies, and the reason behind the seeps appearing on the slopes varies as well.
As long as the slope does not have its final cover, you can attempt to control leachate seeps no matter where the seep location. There are many remedies known to landfill operators for controlling seeps before the final cover, but leachate seeps below the final cover are not controllable. The reason is the seeps are out of reach, and you have no means to control or mitigate the situation. The only potential solution is a seep management system built under the final cover geomembrane at the time of final cover construction.
For landfills with slopes extending up to the top of the landfill without terraces, construct a leachate toe drain system (LTDS) at the toe of the slope adjacent to the landfill perimeter berm. The design will collect and convey liquids emanating from seeps further up on the slope (below the final cover geomembrane) to the leachate collection system. See Figure 1.
For landfills with terraces on the slope, construct LTDSs at every terrace. Best practices call for the location at the toe of the slope, above the terrace, the lowest point of that slope. Consequently, the terrace width prevents seep liquids from flowing further down the slope, and the LTDS at the terrace prevents the accumulation of leachate behind the final cover geomembrane at the interior line of the terrace. See Figure 2.
At the lowest point of the terrace, locate a downspout to convey liquids to the leachate collection system at the bottom of the landfill. You will also need a LTDS at the toe of the slope adjacent to the landfill perimeter berm, as discussed above. You may connect the terrace downspouts to the LTDS located adjacent to the perimeter berm to drain the liquids collected at terraces.
To prevent erosion of fines by small streams of liquids flowing down the slope below the final cover geomembrane use this best practice. This design will prevent depressions forming in the top surface of the final cover. First, place a LTDS geocomposite panel from the source of any leachate seep that you identify on the slope right before the construction of the final cover. Connect the panel to the LTDS pipe-gravel burrito at the terrace or perimeter berm. This solution provides a preferential path for liquids coming out of the seep without causing erosion. See Figures 1 and 2.
Place the LTDS geocomposite below the LTDS burrito when simultaneously constructing the burrito and the LTDS geocomposite. When constructing the LTDS burrito ahead of time, place the LTDS geocomposite above the burrito later. In either case, the contact area between the LTDS burrito and the LTDS geocomposite must be free of soil, which could impede the free flow of liquids to the LTDS burrito.
SCS has a 20-year record of accomplishment solving leachate seeps below the final cover geomembrane. Feel free to contact our landfill designers for advice.
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 and Construction Quality Assurance. He has nearly 40 years of research and professional experience in mechanical, structural, and civil engineering.
Learn more at Landfill Engineering
Pilot-Testing a Novel “Concentrate-&-Destroy” Technology for ‘Green’ and Cost-Effective Destruction of PFAS in Landfill Leachate
One of the recent recipients of EPA’s latest round of small business research grants is investigating a novel technology for treating PFAS in leachate. This project could fill a key technology gap for cost-effectively treating PFAS in landfill leachate. The technology would provide landfill field engineers and decision-makers with a cost-effective solution and mitigate the health impacts as the relevant regulations are rapidly evolving.
The technology is based on an innovative adsorptive photocatalyst (Fe/TNTs@AC) synthesized by modifying low-cost activated carbon (AC) with a cutting-edge photocatalyst, iron-doped titanate nanotubes (Fe/TNTs). The technology works by first concentrating PFAS in water onto Fe/TNTs@AC, and then completely degrading PFAS under UV or solar light. Bench-scale studies indicated that Fe/TNTs@AC can remove >99% of PFOA or PFOS from water via adsorption within 1 hour and degrade nearly 100% of the adsorbed PFAS within 4 hours of UV irradiation. Complete destruction of PFOA also regenerates the material, allowing for repeated uses.
While conventional AC or resins do not degrade PFAS, and while PFAS-saturated AC or resins are hardly regenerable, PFAS on Fe/TNTs@AC are amenable to efficient photocatalytic degradation, which not only destroys PFAS, but regenerates the material. While direct photochemical treatment of PFAS-laden water is often cost-inhibitive, the new technology employs photocatalytic treatment only for spent Fe/TNTs@AC, which is only a fraction of the raw water volume, and thus consumes much less energy.
Phase I commenced on March 1 and runs through August 31, 2020
For more info, see:
Landfill operators may add a casing pipe to their leachate force main for additional environmental protection. Consequently, the leachate force main is entirely located inside a casing pipe where the leachate force main is below ground. In the event of a leak from the leachate force main, liquids stay inside the casing pipe preventing leakage into the ground. During monitoring, checking for the presence of leachate inside of the casing pipes is routine.
For many years, I designed the installation of an HDPE monitoring manhole at each leachate removal sump station. Designed at the top of the perimeter berm, where the leachate force main is normally located, these manholes normally remain dry. The leachate force main crosses through the manhole without discharging into it. The casing pipes connecting to the manholes are open-ended at the manhole, draining directly into it. Easy to monitor, if liquids are present, you probably have a leak.
Using field operations experience, we improved the design.
A blind casing pipe above the surface leaves the leachate line exposed for piping purposes. In this design, the casing pipe does not connect to any vessel for monitoring; instead, it has a pressure gauge or small valve on it for pressure monitoring.
If the gauge reads pressure in the casing pipe, it is indicating there is liquid inside the casing pipe; leachate is leaking from the force main and filling the casing pipe causing the pressure to build. If using a valve, monitoring is opening the valve to look for liquid coming out of the casing pipe. Regularly monitored pressure gauges or valves is a standard operating procedure and easily accomplished.