Landfills are getting larger in height and greater in footprint area, but the location of leachate tanks, leachate ponds, or discharge points to an on-site or off-site leachate treatment plant usually don’t change.
A larger footprint means leachate force mains are getting longer and pumps have to work harder to push leachate through the system to a target point. Some operators carry on with the same pumps for decades and don’t monitor the performance of the pumps after expanding the landfill footprint.
SCS highly recommends that you evaluate the performance of the existing pumps again. Such an evaluation may require hydraulic analysis of the entire network of pipes along with pumps, or whatever segment of the network that is affected by the expansion. The effort is minimal in retrospect, but the operator makes sure that the system will function in an optimized zone with minimal wear on the pumps.
Sometimes the hydraulic evaluation may require up-sizing all or certain pumps in leachate sumps because not enough flow can go through the force main due to high friction loss in the expanded leachate force main. Up-sizing pumps may be achievable depending on the type of the leachate sump, i.e., riser system or vertical manholes. If the up-sized pump in a riser system is too long to fit inside a riser system or too long to the point of making routine maintenance too cumbersome, your engineer needs to come up with another idea.
Booster pumps along an expanded leachate force main can certainly be an option. Booster pumps can be the inline or offline type. Install the inline pumps on the actual force main, and position the offline type on the side so that liquids go through bends and elbows to reach the pump, and again through bends and elbows to get back in the force main. In either case, the booster pump adds hydraulic energy to the flow inside the force main to push the liquids at a higher pressure and velocity through the remainder of the force main and to the target point.
Operators need to be aware of the dynamic nature of the leachate piping network and the role of booster pumps in dynamic environments. After landfill expansion, with new cells coming online -increasing leachate generation, and when closing landfill slopes -decreasing leachate generation over time, the flow in the force main may change. Sometimes booster pumps have to be up-sized or down-sized depending on flow and pressure in the system.
Have a Leachate System question? Contact the author Ali Khatami.
A look at the confusion stemming from regulatory uncertainty of new rules limiting air emissions from municipal solid waste landfills by David Greene, P.E., SCS Engineers – Asheville, NC.
The landfill industry continues to work with EPA Administration to get a longer-term stay to work out needed NSPS/EG rule changes. At this time, industry representatives are hopeful both these related goals can be achieved.
While the new NSPS/EG rules became effective back in 2016, the concerns with the rules raised at the time still remain unresolved. Despite this, we can expect resolution though it may take some time to fix. The fog should be lifting, yielding changes that are expected to be more workable for both the landfill industry and state/local regulators. In the meantime, stay tuned and stay informed.
Read the full article with links to the NSPS/EG update in a recently published SCS Technical Bulletin.
SCS Engineers periodically prepares Technical Bulletins to highlight items of interest to our clients and friends who have signed up to receive them. Our most recent SCS Bulletin summarizes the new rules which took effect on October 28, 2016, with compliance obligations under the NSPS Subpart XXX rule beginning November 28, 2016. Originally, states and local air jurisdictions were to submit their proposed EG rules by May 30, 2017; however, there have been some delays in this process, which we condense and detail in this Bulletin. SCS will continually update coverage of this Rule on our website.
We continue SCS’s Advice from the Field blog series with guidance from an article in MSW Magazine by Daniel R. Cooper, Jason Timmons, and Stephanie Liptak.
The authors of a recent article in MSW Management Magazine present engineering ideas that provide for more efficient construction of a GCCS. Gas system operators will benefit by having fewer pumps to operate and maintain and shallower headers that are more easily accessible. Odor management will be easier along with other benefits.
Read the full article here to learn about the design elements for maximizing long-term benefits, impacting: bottom liners, location of the blower/flare station, leachate risers, extraction well targets, and external header piping.
Temporary Landfill Caps
Temporarily capping landfill slopes is becoming a common measure for landfill operators. There are many benefits to closing landfill slopes with geomembrane on a temporary basis. One of the benefits is delaying construction of the final cover. Following is a discussion of the steps that should be taken to determine whether temporarily capping the slope with geomembrane and postponing the final cover construction is a better financial/operational decision.
Cost Burden
Constructing the final cover is costly, and it is considered an unavoidable expense that has no return on the money spent. Therefore, some operators perform a financial evaluation to determine whether the final cover construction costs can be delayed (provided, of course, that such delays are acceptable to the regulating agency). When evaluating whether to delay the final cover, the cost of maintaining the slopes during the postponement period should be considered. The operator must look at the financial aspects of either closing the slopes with a temporary geomembrane or of leaving the slopes open during the postponement period.
Temporary Landfill Capping Option
The benefits of temporarily capping the slopes during the postponement period may include:
The other side of the coin is the expense associated with the temporary cap. There may be repair costs associated with the geomembrane every few years in order to ensure that the temporary cap remains intact.
Leaving Slopes Open Option
The option of leaving the slopes open during the postponement period involves maintenance expenses such as:
The benefits of leaving the slopes open are twofold: first, the operator will save the costs of constructing the temporary cap; and second, the operator will gain additional airspace as waste settles during the postponement period.
Experience with the Temporary Capping Option
As discussed above, both options provide the benefit of gaining additional airspace during the postponement period. Constructing a temporary cap involves the costs of materials and installation, including the geomembrane and the ballasting system that keeps the geomembrane in place. Generally, the financial and non-tangible benefits of a temporary cap that remains in place five years or longer are more attractive than leaving the slopes open; therefore, most operators choose to install a temporary cap. The next step in the financial evaluation should be comparing the costs of the temporary cap to permanently closing the slopes without postponement.
Final Step in the Financial Evaluation
The next question is whether it makes financial sense to postpone the construction of the final cover.
Waste settlement during the postponement period and the resulting airspace are considered the determining financial factor in choosing the right option. If the present worth value of the airspace generated from waste settlement during the postponement period is greater than the cost to construct the temporary cap at the present time, then the temporary cap option would make financial sense; otherwise, the final cover should be constructed without postponement.
It should be noted that the length of the postponement period plays a very important role in this financial equation. Longer postponement periods have the potential for a greater gain in airspace. Another incentive that should be factored into the financial evaluation is the potential return on the money set aside for the final cover construction during the postponement period.
To assist with this financial evaluation, landfill operators are encouraged to discuss these options with their landfill engineers. Settlement models can be performed to calculate the amount of airspace that may be generated during the postponement period as well as the present worth value of the generated airspace. The returns on the final cover construction costs during the postponement will just be “icing on the cake.”
Read the related Advice From the Field blogs from the landfill and LFG experts at SCS Engineers:
Contact the author: Ali Khatami or your local SCS Engineers’ office.
On October 11, SCS Engineers’ David Hostetter and Phil Carrillo present several case studies during the webinar demonstrating how Remote Control Monitoring (RMC) has lifted the burden of data collection and facilitates the review and analysis of data for use in decision-making.
In this webinar, several case studies regarding remote monitoring and control (RMC) systems for landfill gas and leachate systems will be presented. This includes a description of integrated systems which are used for data collection and analysis and how they were used to identify, troubleshoot and solve real problems in an effective and efficient manner.SCS recognized this as an issue in the industry and developed systems to streamline the process using the latest technology to help perform routine, sometimes complex, data analysis, and to automatically push reports and alerts to operators, engineers, and project managers. This has been a dramatic change that removes human error while reviewing pages of data and allows people to focus on what really matters.
RMC systems give the ability to:
Watch Dave’s video here: https://www.youtube.com/watch?v=pYezcobr1Cg
Dave explains how landfill owners/operators use SCS RMC® to view, operate, and control field equipment. The presentation covers how SCS RMC® helps to reduce operating costs – sending technicians to respond when necessary to alerts from flare systems, leachate systems, and air quality sensors. SCS helps manage all field resources and personnel better while enhancing reporting and data management too.
A variety of CCB/CCP related topics guaranteed to enhance your knowledge. Click the title to read or share these papers.
Jeff Marshall – Mitigating Hydrogen Sulfide Issues at Coal Combustion Residuals and Municipal Solid Waste Co-disposal Sites – Learn about the biological, chemical and physical conditions necessary for FGD decomposition and hydrogen sulfide generation. Marshall will explore technologies that remove and treat hydrogen sulfide from landfill gas and present recommendations for reducing the potential for FGD decomposition at co-disposal facilities.
Eric Nelson and Lindsay Motl – Working Through Location Restrictions to Expand the Ottumwa Midland Landfill – The final Coal Combustion Residual (CCR) rule introduces new challenges for companies developing new landfills or expanding existing sites. Join us to learn how Alliant Energy overcame these challenges and expanded the Ottumwa Midland Landfill (OML) to accommodate increased byproduct disposal rates from new emission control projects.
Steve Lamb and Floyd Cotter – Selecting the Right Closure Cap Option for Your Surface Impoundment or CCR Landfill – Alternative capping options have recently emerged in the industry, such as exposed geomembrane liners or synthetic turf/geomembrane liner systems. Some of these alternative capping options have many advantages over their traditional counterparts. These experts describe the advantages and disadvantages of alternative capping options.
SCS Engineers’ Phillip E. Gearing, PE is a winner of the SWANA 2017 Young Professional Award from the Wisconsin Badger Chapter. The Solid Waste Association of North America honors individuals like Phil who make a significant difference in the solid waste industry.
Phil represents the best of the young professionals working within Wisconsin’s solid waste industry. Clients, contractors, and team members appreciate Phil’s leadership and passion for doing the job right.
He is a dedicated father of three children and an avid fan of all things Wisconsin, namely Badger sports, Green Bay Packer football, and Brewer baseball. Wisconsin from head to toe! Phil was raised on a dairy farm in Jackson County near Merrillan and attended the University of Wisconsin – Madison where he earned his B.S. in Geological Engineering, Geology, and Geophysics.
Phil serves clients out of the SCS Engineers office in Madison, WI.
Read about Phil’s work and SWANA award here.
Despite the fact that you have taken every precaution, hitting utility lines or other hidden infrastructure is still relatively common. Even after all the records are consulted and metal detector tests completed, you can dig up an entire storage tank that wasn’t accounted for or find a random pipe with no apparent usefulness.
Having a tool that can get you down there without damage is a significant benefit to those in the field. SCS recommends using the Hydrovac or Air Knife technologies, tools that can save money and time when working on sites with sensitivities or a longer historical background when the risks are highest.
SCS uses these tools when drilling at a transfer station near older or deeper power lines. We find utilities can be buried deeply below ground or are not encased in metal pipes, making metal detectors useless.
When remediating a historic property for developers with nearby utility lines and there’s a question about the accuracy of the records, it is far safer and cost efficient to use these newer technologies to dig a hole as small as for setting a mailbox, or as large as digging an entire site for construction.
The Hydrovac and Air Knife will both remove soil cover and allow you to see any underground utilities or infrastructure before excavation or drilling. The Hydrovac uses pressurized water and a vacuum system to remove soil. The Air Knife accomplishes the same thing using compressed air instead of water.
SCS Engineers can provide a range of equipment sizes and capabilities including:
By Thomas Karwoski and Sherren Clark
About the Authors:
Mr. Karwoski has 30 years of experience as a hydrogeologist and project manager. He has designed and managed investigations and remediations at existing and proposed landfills; and industrial, Superfund, military, and petroleum sites.
Ms. Clark has more than 25 years of experience in civil engineering and environmental science, with a technical background in both engineering and hydrogeology. She manages multidisciplinary projects including landfill design and monitoring, brownfield site investigation and remediation, and environmental management and permitting for private and public sector clients.
Links to SCS Services: CCR, Landfill, and Remediation pages.
On Friday, Dec. 16, 2016, President Obama signed The Water Infrastructure Improvements for the Nation Act or the “WIIN Act.” Section 2301 of the WIIN Act allows states to establish permit programs to regulate the disposal of coal combustion residuals (CCR) units in lieu of the Environmental Protection Agency’s (EPA) CCR regulations and published at 40 CFR 257, Subpart D, also known as the federal CCR rule, that were effective as of October 19, 2015.
Under the federal CCR rule, enforcement has been through citizen suits brought under Section 7002 of the Resource Conservation and Recovery Act (RCRA). Following WIIN, for CCR disposal facilities operating under an approved permit program, citizen enforcement will be replaced by more traditional state and federal enforcement authorities. It will take time for states to apply for permit authority and to issue permits, and in the meantime the federal CCR rule will continue to be enforced by citizen suits, and utilities will be subject to potentially conflicting interpretations of what is required to comply at a given facility.
Other CCR-related highlights from the WIIN Act include:
The WIIN Act that was passed by the U.S. Congress on Dec. 10, 2016, is based on CCR legislation that has been introduced in the House of Representatives and Senate in various forms over the past 6 years with the support of many in the utility industry. The WIIN Act has been lauded by the U.S. Senate Committee on Environment and Public Works and utility groups alike.
For example:
“This new permitting authority fixes the main problems with the recent coal ash regulation issued by the Environmental Protection Agency, by removing citizen suits as the sole means of enforcement and allowing states to tailor permit requirements on a case-by-case basis.”
“The coal ash language will ensure that states have the authority and flexibility they need to regulate coal ash while protecting the environment as much as the current EPA coal combustion residuals rule,” said APPA Vice President of Government Relations and Counsel Desmarie Waterhouse.
Coal Ash Language Backed by APPA Is Headed to President’s Desk
“…these legislative provisions will enable states to be more involved in the permitting process for the closure of basins.”
EII Applauds Passage of the Water Infrastructure Improvements for the Nation Act
“The bill also injects greatly needed certainty into the regulation of coal ash by giving states clear permitting and enforcement authority and reducing litigation, while providing for its continued beneficial use.”
SCS Engineers will continue to track the WIIN Act and provide you with updates as states consider and make known their approach to developing a CCR permit program, or not.
For questions about the Act or more information, please contact:
Mike McLaughlin, PE, Senior Vice President
Eric Nelson, PE, Vice President
Steve Lamb, PE, Vice President
Kevin Yard, PE, Vice President
Or contact your local SCS Engineers office.
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