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.
In this blog, we discuss the basics of various wastewater treatment methods in use today including process design parameters, advantages, disadvantages, and costs. Some of the wastewater treatment methods are better suited to landfill leachate treatment than others. For example, the traditional activated sludge wastewater treatment technology, discussed in this article is not suitable for landfill leachates, but it has been modified and improved so that its close cousin – for example the membrane bioreactor (MBR) – is much better suited for landfill leachate treatment. The blog is intended for those who manage projects that include leachate treatment but who are not wastewater or process engineers. We start by grouping treatment systems into three basic categories; biological, physical and chemical. Our first blog in the series focuses on biological treatment.
The oldest treatment technology for sanitary wastewater, with the longest track record, is biological treatment. It is effective for treating the type of wastewater generated by humans because it uses naturally occurring microbes to reduce organics, ammonia and other naturally occurring impurities. The modern version of this time-honored biological treatment process (from the 1960s forward) is known as the basic activated sludge (BAS) process. This is the type of treatment that is used at large publicly owned treatment works (POTWs) and the same form of treatment can be used, on a smaller scale, for landfill leachate. The wastewater to be treated, whether it is sanitary wastewater or landfill leachate, contains organic compounds, nutrients (e.g., nitrogen and phosphorus) and naturally occurring microorganisms. When given the right balance of soluble food, temperature, and oxygen, the microorganism population can be increased rapidly. In multiplying their numbers, the microorganisms absorb some of the food sources (organics) in the wastewater for energy and convert that to new cell mass (through cell growth and reproduction), carbon dioxide (CO2), and water.
The actual BAS treatment process involves pumping the raw wastewater through an open tank, aerating and agitating the liquid by mechanically adding air or oxygen typically through a set of fine bubble diffusers, then after a prescribed time, passing that water to another tank called a clarifier. The process is illustrated below.
The dispersion pattern and the buoyancy of the bubbles promote mixing of the tank contents to ensure the bugs are getting adequate oxygen. An example of a bubble diffuser disc and a typical bubble diffuser bank layout is shown in the two photos below.
A process called nitrification also occurs in the aeration tank. Nitrification is a microbial process by which reduced nitrogen compounds (primarily ammonia) are sequentially oxidized to nitrite and nitrate by the species of microbes called Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus.
A biological system, such as a BAS has a susceptibility to some chemicals in leachate that in certain concentrations can be toxic to the “bugs.” For example, high concentrations of ammonia (NH3), chlorides or toxic substances can be harmful. Also, the treatment effectiveness of biological systems drops off significantly at a wastewater temperature lower than about 50 degrees Fahrenheit. Rapid changes in concentrations of these chemicals (or spikes) also can be harmful.
In the clarifier, flocculation chemicals are added to the water to aggregate and help to settle out the cell mass. The cell mass, almost 99% water, is called sludge. Periodically some of the sludge from the clarifier is removed and brought to the front of the process where this “activated” sludge (i.e., air enriched and microbes are alive) is used to seed the incoming wastewater with robust microbial growth and boost the growth of existing organisms that break the organics down. The balance of sludge (called “biosolid”) is removed from the clarifier and is typically dried, disinfected through use of high pH material and or heat and is then used as a soil conditioner directly or as a fertilizer ingredient.
The laboratory measurement of the amount of oxygen that microorganisms use to convert the food to new cell mass is called the biochemical oxygen demand (BOD5). The five day long BOD test was the earliest measure of the organic strength of wastewater and is a rough indication of how much energy (and relative cost) will be expended to treat the wastewater. Landfill leachate is typically considered a strong wastewater compared to municipal wastewater which is considered weak to moderate strength. Many municipal wastewaters are weak because they are heavily diluted with groundwater and infiltration of rainfall.
A key design parameter for any BAS process is the Mixed Liquor Suspended Solids (MLSS). The MLSS is the concentration of suspended solids in the aeration tank. The suspended solids are mostly the active microorganisms that do the work of decomposing the organic substances. The MLSS for a BAS is typically 4,000 to 6,000 mg/l.
Many other water chemistry aspects must be considered with the BAS process. However, these have not been included to simplify this explanation.
Over the decades the BAS process has been modified to address the many different types and strengths of wastewater, increase energy efficiency, reduce treatment times, improve resilience to shock loads, and pollutant removal effectiveness. You may have heard them called Sequencing Batch Reactor (SBR), or powdered activated carbon treatment (PACT). These are variations of the BAS process. Because landfill leachate is somewhat similar in chemical makeup to municipal wastewater, with typically higher chemical constituent concentrations, the landfill sector has successfully borrowed municipal treatment technology. An improvement to the BAS process that started showing up at landfills about 15 to 20 years ago is known as the Membrane Bio-Reactor (MBR) shown here.
The MBR took advantage of advances in micro-manufacturing capability in perfecting synthetic membrane filtration fabric. The membrane, when incorporated in the treatment process, eliminates the need for a clarifier. The membrane works by separating insoluble solids from the water. The advantages of the membrane filtration include;
The membranes are manufactured either as a cylinder shown below-left, or as a flat plate used in a rack outside the BAS reactor, or immersed in the BAS reactor. The diagram shown on the right illustrates the membrane filter process.
Some disadvantages of the MBR can include:
The MBR can manage a much higher MLSS than a conventional BAS; a typical maximum for a BAS is about 4,000 mg/l as compared to around 16,000 mg/l or more in an MBR. The higher MLSS allows for treating a stronger waste stream, and the system has better cold weather and shock load resistance. It can do this because the solids eventually are removed by a membrane. In the BAS process, the chemical treatment in the clarifier forms a large volume of sludge (organic chemicals + microorganisms) that has to be kept in balance by frequent sludge wasting out of the system. Without this wasting, the sludge volume recycled to the aerobic tank would overwhelm the aeration capacity, and the process would collapse. A process flow diagram may look like the one below.
Typically, landfill leachate may need other treatment processes to supplement an MBR system to meet requirements for reducing specific pollutants and other parameters before the treated effluent can be released to the receiving water. One of the key parameters is ammonia (NH3) nitrogen.
Ammonia is produced in the landfill by microorganisms utilizing the organic substances in waste for energy and reproduction in an anaerobic (without oxygen) environment. In an aerobic environment outside the landfill, ammonia can be oxidized by bacteria in a process called nitrification, converting ammonia to nitrite and then to nitrate. When combined with enough phosphorus, nitrates released to surface waters in high enough concentrations can promote algae blooms. The algae blooms typically die off from cold, or their normal lifespan. Large amounts of dead algae compete for oxygen with fish and other wildlife. The result can be fish kills, which can further worsen the water body oxygen depletion problem.
So, in addition to the ammonia being converted to nitrite and then nitrate, the nitrate-nitrogen typically must be removed before discharge of the treated wastewater effluent to surface water. The nitrite and nitrate removal process is known as denitrification and involves reducing the nitrate to nitrogen gas which is inert and not harmful to the environment. Denitrification in the leachate treatment process can be accomplished either by ion exchange, chemical reduction, or biological processes.
The biological method is very common and is typically conducted in a tank known as the anoxic tank. The anoxic tank typically has a filter bed containing the nitrate conversion microorganisms where the nitrate-laden water is passed through for treating. No air is added to maintain an environment that is suitable for the heterotrophic microorganisms that convert nitrate to nitrogen gas. Methanol or acetic acid is typically added to provide a food source for the denitrifying culture in the filters.
Some other key process parameters for the MBR that will affect process sizing and footprint includes the following:
For example, using these unit costs an MBR plant rated at 65,000 GPD would have a basic capital cost of $1.2 to $1.4 million. This does not include a building. The annual operating cost of chemicals and energy only (not including labor), with 90% availability would be $640K to $1.07 million. Extra costs would include; a building if desired or necessary, electrical supply, equalization tank, yard piping, bench and pilot tests, and engineering. These are rough figures to give the reader a sense of the magnitude of costs. Actual costs will differ. It is always best to check with one or more vendors on the unit costs they experience with installations that they provide.
Biological processes have been adapted successfully from the municipal wastewater industry by the wastewater equipment manufacturers who service the solid waste industry to treat landfill leachate. They form the basis of a viable treatment platform that can be expanded depending on the effluent requirements and other design goals. By coupling high-quality membrane filters to remove solids with the BAS-type treatment modifications, MBR plants are revolutionizing leachate treatment. MBR plants are a more efficient and more effective treatment of higher strength leachates. Many vendors are offering modular systems that fit well with the leachate production and growth typical at landfills.
In our next blog, we will discuss membrane filtration systems that are increasingly finding application where leachate has to meet tough discharge standards. Follow SCS Engineers on Twitter, LinkedIn, or Facebook.
Learn more about Liquids Management – Leachate Services
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