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Navigating landfill leachate requirements with geosynthetics

Features | July 1, 2024 | By: Yuse Lajiminmuhip, Anthony Johnson, Bill Urchik and Georgia Covarrubias

FIGURE 1 After the 20-acre Clarksburg Landfill reached the end of its service life, the city scheduled the design and construction of a remedial landfill closure cap in 2019. The city sought a solution that could meet both EPA and state regulations.

How vital is landfill leachate management? Recent guidance from the U.S. Environmental Protection Agency (EPA) on the disposal of PFAS shows that leachate management is one of the core functionalities of a modern landfill—and perhaps one of its biggest selling points moving forward.

Leachate, a byproduct of solid decomposition and precipitation percolation through waste, can contain hazardous substances, including salts, heavy metals and organic matter (Li et al. 2023). The EPA estimates the volume of leachate generated annually in the United States to be 61.1 million m3 (EPA 2022). Despite the alarming volume, only 6% of United States landfills can manage on-site leachate, with the majority relying on wastewater treatment plants (William 2019; Staley and Bolyard 2018).

However, changing regulatory conditions and other considerations could swing the pendulum in favor of developing more on-site solutions. Regardless, geosynthetics are essential to any municipal waste landfill and can be designed to support simple to robust leachate management systems. This article provides the latest summary on tackling landfill leachate with geosynthetics.

Geosynthetics and designs for landfill leachate management

Figure 2 The concentration of different per- and poly-fluoroalkyl substances in landfill leachate was collected from an extensive literature survey (5).

Landfill leachate represents a unique waste management challenge, creating a complex composition that often surpasses conventional wastewater (Figure 2). Table 1 summarizes considerations when managing landfill leachate. Despite some of these challenges, leachate offers opportunities for resource recovery, such as the extraction of ammonia, phosphorus and humic acids, which can provide environmental and economic benefits (Golwala et al. 2022; Benson et al. 2017; Iskander et al. 2016).

All these design considerations highlight the value of geosynthetics, which come in various forms  and designs to offer cost-efficient ways to design safe and long-lasting landfills (Junqueira et al. 2006).

Table 1 A summary of considerations in landfill leachate management (1, 2, 5–7).

Geomembranes as a barrier

Environmental conservation relies on barriers to keep contaminated water from polluting clean water. Geosynthetic barriers, or geomembranes, support landfill leachate management. Due to their physical properties, these geomembranes exhibit very low permeability and formidable resistance against various chemicals and compounds that would degrade many other materials (Needham et al. 2006; Rowe and Sangam 2002). They play a crucial role in landfills by effectively preventing harmful leachate migration, fortifying the protection of groundwater reservoirs and surrounding ecosystems (Touze-Foltz et al. 2021, S’habou and Salem 2023).

Continued research emphasizes the importance of material choice, precise installation and regular maintenance for effective containment (Touze-Foltz et al. 2021; Cazzuffi et al. 2010). Advances in geomembrane technology enhance stability and resilience to environmental stressors (Kavazanjian et al. 2006; Wu and Shu 2012), extending their utility to hydraulic structures and floodwater containment (Sun et al. 2020; Vorlet and De Cesare 2024).

Geocomposite acting as a transport layer for leachate collection and detection

In recent years, geocomposites have revolutionized leachate management. These engineered materials, comprised of products such as geotextiles and geonets, offer drainage, filtration and other continuous benefits. Their integration into collection systems simplifies leachate removal, reducing hydraulic pressure and enhancing containment of harmful constituents (Khire and Haydar 2005). Notably, they outperform conventional sand filters with thinner profiles, which increases airspace and offers superior hydraulic performance (Semach et al. 2011).

When employed within leachate collection layers, geocomposites present several advantages, including their resistance to biological clogging and ability to maintain landfill infrastructure functionality when paired with geotextile filters (Fourmont et al. 2012; Koerner et al. 1993). Integrating geocomposites with geomembranes in composite liner systems enhances leachate management strategies, offering contamination barriers and efficient leachate collection and disposal mechanisms.

Figure 3 Clarksburg Landfill saw significant material and labor cost reductions through the use of an AGRU Integrated Drainage System (IDS).

Geomembranes with low PFAS diffusion rates

Contemporary research and EPA guidance underscore the role of geomembranes in PFAS waste containment. Geomembranes made from linear low-density polyethylene (LLDPE) exhibit minimal diffusion, demonstrating enhanced performance in minimizing PFAS migration in landfill leachate (Di Battista et al. 2020; Ahmad et al. 2024; Rowe et al. 2023).

Experts have recommended using a double-lined composite barrier system for the best possible performance with current geosynthetic materials. This system comprises a geomembrane as the primary containment system, as described above, followed by a secondary system that uses clay or geosynthetic clay liner (GCL).

Figure 4 The Ruby Waste Rock Repository contained over 65 acres of waste from the Gilt Edge Mine. A robust closure cap with drainage was necessary to reduce acid rock drainage (ARD) from contaminating the local water supply.

AGRU lining systems for leachate management

An essential component of any leachate management plan is managing infiltration. Below is a summary of an AGRU case study demonstrating the successful implementation of closure solutions to significantly reduce infiltration and, therefore, help reduce leachate generation. The second AGRU case study details how a cap was installed in a mining waste pile to protect against water infiltration.

After the Clarksburg, W. Va., landfill decommissioned, the city initiated the construction and design of a remedial landfill closure cap. To manage costs, the city chose a design incorporating HDPE geomembrane, double-sided geocomposites and geotextiles. The chosen approach utilized AGRU IDS, a Subtitle D-compliant closure and containment solution, in conjunction with a geocomposite venting system. The project was completed in 2019. The landfill cap is expected to reduce infiltration and provide environmental protection throughout its service.

In Black Hills, S.D., Gilt Edge Mine, operating since 1876, accumulated approximately 20 million cubic yards of waste material, leading to acid rock drainage (ARD) and groundwater contamination. To provide adequate protection against water infiltration, a cap system was designed using a structured geomembrane with an integral drain layer. This barrier would be installed over the 65 acres (26.3 hectares) of waste rock. One challenge with this large area was controlling the stability of the cap system along with the flow of water along the slope, which extended longer than 1,804 feet (550 m). A series of nine 8-meter side slope benches were created. These drainage ditches can control the water flow for even 100-year storm events.

The final cover system comprised six layers. At the top was processed topsoil seeded with native grasses. Beneath that was a 900 mm (.9 m) layer of rock and soil. A 450 mm (.45 m) layer of crushed 25 mm (.025 m) rocks separated the soil from a 10 oz/yd2 grade nonwoven geotextile. The last two layers comprised an 80 mil LLDPE structured geomembrane with an integrated drain layer. The ditches were lined with a geocomposite lining system with a high-grade geosynthetic material. This project was completed in 2003. The approach offered significant material and labor cost reductions by not having to purchase and install a separate geonet drain layer thanks to AGRU IDS.

Summary

Geosynthetics are essential in helping manage landfill leachate to mitigate environmental and public health risks associated with hazardous materials.

References 

Li, Q. et al. (2023). “Challenges and engineering application of landfill leachate concentrate treatment.” Environmental Research, 231. 

EPA. (2022). “2022 Progress Report: Occurrence, fate, transport, and treatment of per- and polyfluoroalkyl substances (PFASs) in landfill leachate.” Environmental Protection Agency. 

Cunningham, W. (2019). “Locking up leachate.” Wastewater Digest.

Staley, B. and Bolyard, S.C. (2018). “State of practice of landfill leachate management and treatment.” U.S. Global Waste Management Symposium.

Golwala, H. et al. (2022). “Advancement and challenges in municipal landfill leachate treatment–the path forward.” ACS ES&T Water, 2(8), 1289-1300.

Benson, C.H. (2017). “Characteristics of gas and leachate at an elevated temperature landfill.” Geotechnical Frontiers 2017.

Iskander. S.M., Brazil, B., Novak, J.T., and He, Z. (2016). “Resource recovery from landfill leachate using bioelectrochemical systems: Opportunities, challenges, and perspectives.” Bioresour Technology, 201, 347-354.

Junqueira, F.F., Silva, A.R.L., and Palmeira, E.M. (2006). “Performance of drainage systems incorporating geosynthetics and their effect on leachate properties.” Geotextiles and Geomembranes, 24(5), 311-24. 

Needham, A.D., Smith, J.W.N., and Gallagher, E.M.G. (2006). “The service life of polyethylene geomembrane barriers.” Engineering Geology, 85(1-2), 82-90.

Rowe, R.K. and Sangam, H.P. (2002). “Durability of HDPE geomembranes.” Geotextiles and Geomembranes, 20(2), 77-95.

Touze-Foltz, N., Xie, H., and Stoltz, G. (2021). “Performance issues of barrier systems for landfills: A review.” Geotextiles and Geomembranes, 49(2), 475-488. 

S’habou, R. and Salem, Z.B. (2023). “The use of geomembrane as a remediation towards a sustainable OMWW landfilling: Case study of Agareb site in Sfax, Tunisia.” E3S Web of Conferences. 

Cazzuffi, D., Giroud, J., Scuero, A., and Vaschetti, G. (2010). “Geosynthetic barriers systems for dams.” 9th International Conference on Geosynthetics.

Kavazanjian E. et al. (2006). “Geosynthetic barriers for environmental protection at landfills.” Geosynthetics 8th International Conference on Geosynthetics.

Wu, H. and Shu, Y. (2012). “Stability of geomembrane surface barrier of earth dam considering strain-softening characteristic of geosynthetic interface.” KSCE Journal of Civil Engineering, 16(7). 

Sun, L. et al. (2020). “Stability of supported geomembrane tube flood barriers of novel design.” Journal of Flood Risk Management, 13(1). 

Vorlet, S.L. and De Cesare, G. (2024). “A comprehensive review on geomembrane systems application in hydropower.” Renewable and Sustainable Energy Reviews, 189. 

Khire. M.V. and Haydar, M.M. (2005). “Leachate recirculation using geocomposite drainage layer in engineered MSW landfills.” Waste Containment and Remediation.

Semach, A.C., Zych, G., Wolfe, W., and Butalia, T. (2011). “Laboratory analysis of geocomposites for use in drainage systems in CCP landfills.” World of Coal Ash Conference, Denver, Colorado.

Fourmont, S., Blond, E., Bloquet, C., and Budka, A. (2012). “Biological clogging resistance of tubular drainage geocomposites in leachate collection layers”. 5th European Geosynthetics Congress, Valencia.

Koerner, G.R., Koerner, R., and Martin, J.P. (1993). “Performance evaluation of geotextile filters used in leachate collection systems of solid waste landfills.” Journal of Geotechnical Engineering, 120(10).

Di Battista. V., Rowe, R.K., Patch, D., and Weber, K. (2020). “FOA and PFOS diffusion through LLDPE and LLDPE coextruded with EVOH at 22 C, 35 C, and 50 C.” Waste Management, 117, 93-103. 

Ahmad, A., Tian, K., Tanyu, B., and Foster, G.D. (2024). “Sorption and diffusion of per-polyfluoroalkyl substances (PFAS) in high-density polyethylene geomembranes.” Waste Management, 174, 15-23. 

Rowe, R.K., Barakat, F.B., Patch, D., and Weber, K. (2023). “Diffusion and partitioning of different PFAS compounds through thermoplastic polyurethane and three different PVC-EIA liners.” Science of The Total Environment, 892. 

Yuse Lajiminmuhip is the marketing business unit manager at AGRU America, Inc. and also serves as a co-chair for the IGS Sustainability Committee.

Anthony Johnson is the technical business unit manager at AGRU America, Inc. and is active within GRI, IGS, and ASTM, contributing to the industry’s development of geosynthetics and HDPE pipes. 

Bill Urchik is an applications engineer at AGRU America, Inc., specializing in geosynthetics. He has a civil engineering degree in structural and geotechnical engineering from The University of Western Ontario.

Georgia Covarrubias is a marketing assistant at AGRU America, Inc. and is attending the College of Charleston for a B.S. in marketing.  


Project Highlights

CLARKSBURG LANDFILL

Location: Clarksburg, W. Va. 

Engineering Consultant and Environmental Permitting: MSES Consultants, WV Landfill Closure Assistance Program (LCAP)

Geosynthetic Liner: AGRU 50-mil HDPE Super Gripnet

Geocomposite: AGRU 6/200/6

GeoTextile: AGRUTEX 061

Manufacturer: AGRU

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