The Solid Waste Association of North America (SWANA) is hosting a virtual Landfill Challenges Summit on Thursday, June 17.
This half-day, virtual event will bring together landfill, landfill gas, and biogas professionals from throughout the United States and Canada. Industry experts from the public and private sectors will discuss current and future challenges that are expected to impact landfill operations and landfill gas production, and what lessons can be applied as we move forward.
The virtual summit will be followed by an on-line networking event.
Here at SCS, we work for developers, industry, and manufacturers to help them run cleaner, safer, and more efficiently. This PBS video provides insight into how SCS brings value to the waste industry, our clients, and, most importantly, our communities.
You may ask yourself, don’t pig farms create pollution? Yes, but even that waste is reusable!
Did you know the food you buy in the grocery is supported by our environmental experts? Learn more about SCS’s environmental engineers and consultants who bring contaminated properties back to life, lower and capture greenhouse gases for fuels and renewable energy, and make possible a brighter future.
If you are interested in becoming an SCS Engineers employee-owner, watch our comprehensive video to see the breadth of services our teams offer.
Recorded Live Thursday, June 10 at 2:00 pm ET
GIS improves operational efficiency at waste facilities, landfills and helps keep development projects on schedule. GIS technology transforms volumes of collected data into maps and easy-to-understand dashboards – making staff assignments and decisions more precise and timely.
Our panelists use case studies to demonstrate how they use this proven technology in new ways to improve forensic, diagnostic, and planning activities. Join us to learn how your operation may also leverage GIS to address these challenges:
Landfills: Operators make diagnostic and forensic use of GIS to address maintenance tasks faster. We’ll cover modeling 3D wells and liquid level data, showing how GIS embedded dashboards and infographics pinpoint exactly where to assign staff. At the same time, supervisors monitor completed assignments seeing real-time results and what still needs attention.
Siting Facilities: Decision-makers use multi-criteria decision analysis incorporated into a geographic information system to account for relevant technical data, environmental, social, and economic factors during the site selection of a waste transfer station. The resulting maps and infographics are useful at public meetings too.
Property Development: Time is money on development projects. Environmental engineers use GIS to more accurately pinpoint potential contamination sources, conduct site assessments, strategize remediation solutions, and see sampling results weeks faster. Infographics and dashboards show if and exactly where to continue sampling without waiting weeks or months for reports.
Among the extensive list of landfill operating costs are those incurred for landscaping to keep the slopes trimmed. While regularly mowing large spaces is expensive, keeping sites well-groomed is essential for protecting landfill covers and providing other safeguards. Putting sheep and other grazing livestock to work eliminating invasive plants and other vegetation from properties difficult to traverse for two-legged workers could be a good alternative. Grazing is an often useful technique for maintaining traditional native plants while reducing weeds and unwanted vegetation, mitigating risk for growth to dry out and possibly catch fire or intrude on a site’s pipelines and infrastructure.
In municipal solid waste landfills near urban areas, such as in Pennsylvania, Arizona, and California, grazing animals are helping with slope management. These locations also reap environmental benefits of reduced soil erosion; improved air and water quality; better plant diversity, vigor and production; and improved wildlife habitat.
As with all landfill operations, planning is everything. The choice of grazing animal (i.e., sheep, goats, cattle, or horses) and the number of animals necessary is site-specific. To determine the best choices, SCS Engineers looks at site characteristics such as the age of the plants and the proportion of grass species present, the local climate, and wildlife species present.
A landfill operator in California using sheep to groom landfill slopes is pleased with the results after three months and plans to continue the grazing method in the upcoming years. “We use 400 sheep per acre, per day, and have 600 on-site.”
“We talked about it for years before we implemented this method,” he says. “We needed time to research the feasibility and the costs, but that isn’t a challenge for SCS; their environmental scientists have landfill expertise in gauging air, soil, water, inorganic and organic content. These are all conditions requiring careful consideration before bringing in sheep to graze.”
The operator was sold on grazing, seeing the environmental, economic, and safety benefits of this alternative to herbicides and staff maneuvering trimming equipment on steep slopes. Finding a shepherd was the next step. With all its benefits, the method does require human oversight.
Luis lives at the landfill in a trailer home, his base of operations. He grew up in Peru, herding sheep. The landfill operations staff trained him on landfill safety, and Luis, in turn, teaches landfill staff what to expect from the 600 sheep.
The herd grazes during daylight hours, clearing patches of mustard grass and weeds. “Sheep are a better choice than goats here; they are more selective and won’t eat native plants or damage the infrastructure by trying to eat it too,” says the landfill operator.
As the sheep graze on invasive grasses, they are preventing tumbleweeds and destroying the seeds while chewing. A further benefit is the fertilizer they leave behind supports the growth of native plants that require minimal grooming, are tolerant of dry conditions, and facilitate the protection of the landfill cover.
“Around here, where the climate is very dry, preventing tumbleweeds and flammable conditions is a priority. The herd is packing the groundcover down while they’re eating, providing a great alternative to mowing while helping control runoff,” says the operator.
The herd is low maintenance, thriving outdoors without shelter and needing only to have their water troughs filled. The shepherd has two helpers, a border collie for herding the sheep to new locations and another larger dog to help protect the sheep from coyotes. Both the dogs and the wildlife help cut down the number of burrowing animals, which for obvious reasons are not landfill-friendly.
Occasionally, the landfill operation staff helps Luis move the herd. He sets up new locations across the landfill as the sheep are grazing in another area. Then the dogs help move the herd to the new location. Keeping the sheep going in the right direction is hard work, explains SCS’s Regional Manager. “If one sheep breaks off, twenty more will follow. Depending on where we’re moving them, Luis may need extra hands.”
This natural “landscaping” alternative with all its landfill-specific benefits is working well. The sheep can do some damage, they sometimes rub along exposed pipelines scratching themselves, but the staff is quickly alerted to anything broken. Luis uses a lightweight grid fence to corral the animals. The battery-powered fencing helps protect the sheep at night from coyotes with a light “shocking” deterrent, similar to static electricity. It’s enough to keep the carnivores at bay along with the dogs’ help.
The SCS landfill operations team has adopted the two dogs. Their Field Services Regional Manager points out, “We didn’t plan on adopting them, but we just couldn’t help ourselves. These are hardworking animals, and Guardian, the dog protecting the sheep at night, can get Foxtail, a grass-like weed, caught in his fur. The seeds can injure dogs, so we inspect and brush them, and we watch to ensure they stay healthy. These dogs, like the sheep, are part of the team and important to helping maintain the landfill − not to mention they’re special to us.”
The sheep, dogs, and Luis are doing an exemplary job. The operator expects in two or three seasons to see a significant improvement in maintenance; each consecutive year, there is less undesirable vegetation. “It’s working well; next year, we will start grazing in January to help prevent more invasive new growth earlier in the season,” he says.
“Environmentally, I like to think we’re helping our client be a good neighbor,” he continues. “And we save the landfill 66 percent of their landscaping budget every year; that helps us all sleep better.”
The U.S. Environmental Protection Agency recommends ecological restoration and revegetation of landfills, abandoned dumps, mines, and other site containment systems designed to protect people and the environment from exposure and prevent contaminant migration. Grazing is one cost-effective and efficient option to consider supporting these priorities.
The Solid Waste Association of North America (SWANA) is hosting a virtual summit in place of SOAR this June 17th. The Landfill Challenges Summit presents sessions from 12:00 – 5:00 pm EDT and on-demand sessions throughout the conference.
The Landfill Challenges Summit brings together landfill, landfill gas, and biogas professionals throughout the United States and Canada. Industry experts, including those at SCS Engineers, will discuss current and future challenges that are expected to impact landfill operations and landfill gas production and what lessons can be applied as we move forward.
As vacant land becomes more scarce, developers are turning to former landfills, which are often large tracts in prime locations, are now use. Daniel Cooper and Somshekhar Kundral use examples demonstrating how landfills and lakefills may be reclaimed, allowing the community to realize economic benefits in previously unusable areas for development while improving environmental protection. However, redevelopment on such site poses several environmental and geotechnical challenges. The design concepts of methane gas management systems vary based on the site’s subsurface conditions, building footprint, and the perceived risk tolerance of building owners. Several gas management barriers are available in the market today and can be broadly classified into the asphaltic spray-applied liner and the HDPE liner. The use of these liner systems depends on subsurface conditions and the size of the building. SWANA CEU: .50
SCS Engineers periodically prepares SCS Technical Bulletins – short, clear summaries of U.S. Environmental Protection Agency (EPA) rules and plans. On May 21, 2021, the EPA published a Federal Plan to implement the new Emission Guideline (EG) rule for municipal solid waste (MSW) landfills. The Federal Plan is published under Title 40 of the Code of Federal Regulations (CFR) Part 62, Subpart OOO.
Read, share, download the Federal Plan for Landfill EG Rule Tech Bulletin here.
It goes without saying: landfill operators are forever working to stay on top of odors, especially when the community smells something and points to the landfill or when regulators come calling. This blog shares two odor stories: one around landfill gas and another around trash. Then it looks at what happened when an operator got a permit restriction over alleged hydrogen sulfide emissions; odor was not the problem here. It was a perceived health risk; learn how SCS proved a predictive model was off the mark.
Is Landfill Gas a Source of Community Odors? And Ensuring Compliance
Living up to landfill odor nuisance standards is tough. The underlying premise is that odors must limit peoples’ ability to enjoy life or property to create a public nuisance, but it’s a subjective call. How strong an odor is and sometimes even if it exists depends on perception, so the question becomes: when they aren’t sure what they are being measured against, how do operators comply and prove compliance?
SCS recently helped a client figure out how to accomplish this after receiving odor complaints from the community, ultimately leading to a state agency-issued violation.
“We needed to thoroughly investigate to identify and mitigate odors, then prove compliance to the state regulator. Making a strong, valid case without having a numeric standard to go by takes both creativity and a scientific approach,” says Pat Sullivan, SCS senior vice president.
Sullivan, a biologist and his team of meteorologists, air dispersion modelers, and engineers, had a good starting point. They knew landfill gas was the source of the problem. But they needed more data to get to the root of that problem, and the operator’s required surface monitoring did not tell enough of the story.
The team launched a series of studies relying on multiple investigative tools.
“When we may have to put in more gas collection components, as we did here, we want to be sure we install them exactly where they are needed. This entails going above and beyond the standard modeling with a more rigorous methodology to get a comprehensive landfill gas emissions footprint,” Sullivan says.
SCS began by bringing out a drone to reach more landfill areas than technicians on foot for better coverage. The drone can fly over slopes, areas too dangerous to walk due to constant movement of heavy equipment, and areas inaccessible because of snow and ice. As it flies, it shoots a laser, which identifies methane based on the light refraction by methane molecules—then incorporates the data into a map for a comprehensive, visual picture.
Knowing methane concentrations at specific locations is important, but determining where to be more vigilant in controlling landfill gas also requires knowing hydrogen sulfide (H2S) concentrations. Sometimes overall methane levels are within acceptable limits, but the hydrogen sulfide in it is elevated, which could be a problem, Sullivan explains.
Getting a good grasp on H2S’s potential impact is tricky, as levels can vary radically from one area of the landfill to another. Pat Sullivan, SCS senior vice president, has seen them range from 100 parts per million to as high as 100,000 at different locations.
SCS used a Jerome meter, a highly sensitive tool that precisely quantifies H2S down to low-level part per million levels. SCS took it across the landfill and then into the community in search of H2S hot spots.
At the same time that the team investigated surface emissions of H2S, they went deeper down, sampling each landfill gas extraction well for levels of this volatile sulfur compound to identify potentially problematic spots within the landfill gas system.
“For this, we used Dräger sampling tubes, a resourceful tool in that rather than sending 100 samples to the lab, we analyze them ourselves and get immediate results,” Sullivan says.
Technicians get accurate quantitative results within plus or minus about 20% and can view concentration readings out in the field. Results are recorded on field logs and entered into a database for future analysis.
SCS overlaid the methane data from the drone study with the H2S data on both surface emissions and wells to develop a roadmap to design a landfill gas system upgrade. It includes new wells and piping in focused areas and more blowers for increasing the vacuum to pull more gas.
“We saw immediate results,” Sullivan says.
“Total gas collected went up 15 to 20 percent. Complaints went down significantly, and our client has not received another violation since.”
Of course, as the landfill takes in more trash, it will generate more gas, so due diligence is ongoing.
“Problem-solving is a phased approach. You do what you determine to be most effective; evaluate; then do additional work to improve. We will continue to follow this site and fine-tune where needed to keep the system running efficiently and keep the community and regulators happy,” Sullivan says.
Taking Down Landfill Odors from Trash
New garbage on a landfill’s active face can be a source of offsite odors, but determining if the waste facility is responsible, and determining when, where, and how odors travel, takes forensic work. Landfill odor experts rely on multiple data sets and tools to understand what can be complex issues and ultimately devise the most effective odor mitigation program when necessary.
In a couple of recent scenarios in Southern California, SCS combined complaint data, meteorological data, and smoke studies to get a full picture that verified the decomposing waste was the odor source. Then staff helped nail down specific times the problem occurred and under what conditions; providing a concise window can save operators labor and other resources because they can execute proactive measures only when needed.
“We look at complaint data to learn the location, day, and time of the complaint, but these accounts are not reliable by themselves. So, we overlay this information with meteorological data to determine the wind conditions during those days and times. Weather-related data is important in vetting offsite odors because if the landfill is not upwind of the location when the complaints happen, there likely is another source,” says Pat Sullivan, SCS senior vice president.
Sullivan and his team begin their investigations in two possible ways – setting up meteorological stations at strategic areas on the landfill to capture wind-related data or capturing data from already situated stations. Then they produce wind roses from their findings, which graphically represent wind speed; how often the wind blows from certain directions; and how these two correlate. In these two scenarios, graphing wind data times during each day helped determine exactly when specific wind conditions are prevalent.
In one of the two cases, odors occurred in the summer and almost always in the morning. The data not only showed where the winds were coming from at those times, but also showed they were traveling at low to moderate speeds.
“We matched that information to complaints and confirmed that the wind conditions were indeed driving the odors,” Sullivan says, explaining the speeds were just enough to carry the odor molecules into the community but not high enough to disperse and dilute them.
“Now we have painted a picture of wind conditions that we can focus on to get more information. We are getting closer to designing a multi-tiered odor mitigation program,” he says.
The next step was a smoke study, which reveals how odors move offsite, identifying the exact pathways and movement trajectory. These details are important because to treat or disrupt odor molecules; operators need to intersect the odor plume before it leaves the site.
SCS odor experts release colored smoke at the time and location they believe odors are, based on the meteorological data. They film from a drone to get a bird’s eye view of the smoke plume as well as get a camera filming from a different angle, following the plume movement to identify its path out of the landfill. This method enables them to determine where to intersect the odors as they move through the air before leaving the site.
From this research came three recommended measures to take during unfavorable wind conditions:
One of the landfill operators now has the problem under control and has received no further violations.
The other site made many of the same changes and plans to open a second disposal area for smelly loads. This client has seen a significant reduction in complaints and violations, but it’s a work in progress. The next true test will come when Sullivan and his team reevaluate in the summer.
“We will see then if any improvements are needed and tweak the solution if needed.”
And as with our other clients, we are training operators on how to be proactive. We teach them how to identify and grade odors and how to follow set procedures. And we help them with strategy implementation,” he says.
Odor mitigation is an ongoing undertaking. The team continually assesses and quantifies emissions and potential impacts.
“We look for changes that will control odors or prevent them in the first place. And we provide clients with the know-how and support to stay ahead today and into the future. Landfills and waste volumes are growing and changing. It’s a dynamic scenario. And we continue to build on what we have proven and adjust to keep up to make more progress,” Sullivan says.
Showing That a Model Can Over Predict H2S Emissions
Hydrogen sulfide (H2S) can be problematic even at very low concentrations, so this volatile sulfur compound is on federal, state, and local regulators’ radar. Some jurisdictions require the evaluation of air toxic emissions to determine potential health impacts to nearby communities.
They are also calling for these evaluations during permitting or to decide when controls are needed. To make these impact determinations, regulators typically rely on standard H2S risk assessments leveraging air dispersion modeling that predicts concentrations at locations away from the source.
However, this methodology, which includes estimates of emissions and predicts offsite concentrations based on algorithms that mimic how air moves, is not always accurate. Inaccuracy proved to be the case at one SCS client’s site. The model overpredicted offsite measurements of H2S that the state and local agency classifies as toxic.
Ultimately, the client entered into an enforcement agreement with the state because the operator had a permit limit, based on results of the risk assessment that it could not meet.
“Respectfully, the agency came in maintaining that the levels were out of compliance; it came as a surprise and seemed questionable to our team given our experience. We felt that the air modeling and risk assessment results derived from this modeling were not accurate,” says Sullivan.
First, his team tried to adjust model inputs and variables that would yield what they believed would be more accurate data. Even though they could show improvements, the model adjustments could not obtain readings that showed compliance with the risk-based limits.
Next, they began going out monthly and measuring real concentrations at receptor locations. The team used a Jerome sensor, a highly sensitive handheld device that detects H2S down to single-digit parts per billion levels with good accuracy.
When they compared the predictions from the standard model to their readings on the same days of each month and same times of day, they confirmed the concentrations were well below the acceptable risk threshold.
“Because we did this over an extended period, we have continuous readings and a large data set from many locations that give a history and statistical validity,” Sullivan says. Every monitored value was substantially lower than the values predicted by the model.
“What that means is we could show that while there were onsite emissions, they were not escaping the landfill at levels that would exceed risk-based thresholds. That was useful in proving to the regulators that the landfill was actually in compliance with the standard, even when the model suggested it was not,” Sullivan says.
Now SCS is asking for revising its client’s permit and that the limitations are made more flexible based on real-time, longer-term findings. While the team is still waiting on the final permit decision, they’re confident they have proof that the site complies with the risk-based limit.
The outcome of this project has potential beyond possibly changing one permit for one operator, Sullivan surmises.
“We think the data developed from this study showing how the models can overestimate real-world conditions can ideally help other operators build a sound case in circumstances where they truly are in compliance.”
Staying Ahead of Odor Management at Solid Waste Facilities – This video recording is from a live session about the challenges of odors, including measuring them and the science behind them. Throughout the recording, the speakers’ field questions as they make recommendations for assessing and avoiding odors, regulatory issues, litigation, and responding to complaints.
The presentation and Q&A run for 1 hour 41 min. It’s well worth your time, with plenty of questions posed by solid waste facility operators, landfill managers, and composting operators answered.
SCS Engineers encourages you to share this video or any from our Learning Center. You can embed them at events and use them for in-house training. Look for our next webinar in June 2021. If you’d like to attend a live session or request our presentation slides, please email us at .
(40 CFR Part 60, Subpart OOO)
EPA is submitting a pre-publication copy of the final MSW Landfills Federal Plan to implement the Emission Guidelines (EG) and Compliance Times issued on May 10, 2021. The Final Plan becomes effective 30 days after publication in the Federal Register, impacting any remaining landfills without approved EG Cf rules.
EPA’s federal plan includes an inventory of designated facilities and an estimate of emissions from those designated facilities. The Agency estimates 1,590 landfills will potentially be covered in 42 states and the US territories of Puerto Rico and the Virgin Islands, and one tribal entity.
SCS Engineers is preparing a Technical Bulletin for distribution to our mailing list and on social media. The Bulletin will consolidate 133 pages into several pages highlighting significant dates and impacts for you.
Affected are MSW landfills that commenced construction on or before July 17, 2014, and have not been modified or reconstructed since July 17, 2014.
EPA is implementing emission guideline requirements for existing MSW landfills located in states and Indian country where state plans or tribal plans are not currently in effect because they were not submitted or approved.
The Final 2016 Emission Guidelines for MSW Landfills require existing landfills that reach a landfill gas emissions threshold of 34 metric tons of nonmethane organic compounds (NMOC) or more per year to install a system to collect and control landfill gas (GCCS).
It also implements the emission limits, compliance schedules, testing, monitoring, reporting and recordkeeping requirements established in the Emission Guidelines for MSW Landfills.
Unless the landfill is a legacy controlled landfill, owners or operators of MSW landfills subject to the MSW Landfills Federal Plan must submit a design capacity report within 90 days after the effective date of the Federal plan (40 CFR 62.16724(a)).
Should the design capacity report indicate a capacity equal to or greater than 2.5 million Mg and 2.5 million m3 of solid waste a landfill can accept; then, an annual NMOC emission rate report must also be submitted within 90 days after the effective date of the Federal plan, and then every 12 months until the landfill installs a GCCS (40 CFR 62.16724(c)).
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.
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.