Solid Waste Management

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Course Learning Outcomes for Unit VII Upon completion of this unit, students should be able to:

2. Evaluate the evolution of technologies related to solid waste management. 2.1 Summarize the evolution of municipal solid waste landfills.

5. Describe best practices of solid waste management in an urban society.

5.1 Articulate requirements for municipal solid waste landfills.

Course/Unit Learning Outcomes

Learning Activity

2.1 Unit Lesson Chapter 8, pp. 328–387 Unit VII PowerPoint Presentation

5.1 Unit Lesson Chapter 8, pp. 328–387 Unit VII PowerPoint Presentation

Required Unit Resources Chapter 8: Landfills, pp. 328–387

Unit Lesson

Introduction We are now in Unit VII. So far in this course, we have learned about solid waste regulations, solid waste's impact on human populations, the collection of solid waste, mechanical processes for breaking up solid waste, separation processes, biological treatment, and thermal treatment. In the course, we have found benefits to materials that end up in solid waste. For example, metals can be separated and recycled, and biologically active organic matter, such as food waste, can be separated and treated aerobically (composted) or anaerobically. Paper, wood, and plastics are prime materials for combustion. Though it would be nice to have all solid waste culminate with a beneficial afterlife, it is rare for communities not to have some leftover material. This leftover material is disposed of in landfills. Most small communities in the United States use landfills as their only option for solid waste. Though many homes in small communities may have their compost piles or some individuals who drive recyclables some distance to a recycling facility, the only institutional solid waste option may well be the landfill. Larger cities generally have many more solid waste options, such as community-wide recycling, composting, or thermal treatment. The larger communities still have landfills (often quite large), but a smaller percentage of household solid waste goes to the landfill in a large community compared to a small one. This lesson will focus on landfills.

UNIT VII STUDY GUIDE

Landfill Evolution and Best Practices

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Landfills With the passage in 1976 of the federal Resource Conservation and Recovery Act (RCRA), minimum requirements for siting, design, and operation of municipal solid waste landfills were codified by the U.S. Environmental Protection Agency (EPA). These rules are described in the Code of Federal Regulations in Title 40, Part 258, which is abbreviated as 40 C.F.R. 258 (Criteria for Municipal Solid Waste, 1991). Every state in the United States has an environmental agency. State rules must be at least as strong as the federal rules. 40 C.F.R. 258 contains Subparts A through G. The subparts cover the topics listed below.

A) General information, such as definitions and relevancy of other federal laws B) Location restrictions, such as proximity to airports, floodplains, wetlands, and seismic faults C) Operating criteria, such as daily cover and emissions D) Design criteria, such as liners and monitoring wells E) Groundwater monitoring to prevent offsite contamination F) Landfill closure to prevent future offsite contamination G) Financial assurance (Criteria for Municipal Solid Waste, 1991)

This lesson will focus on Subparts B through F.

Location Restrictions Airport Proximity Location restrictions in 40 C.F.R. 258 are related to airport proximity, floodplains, wetlands, faults, and closure limitations. A concern with airports and nearby landfills is that landfilled materials attract a variety of birds. The birds present a threat to aircraft since they can get sucked into jet engines or get churned in propellers. Not only do the birds suffer, but aircraft safety is at risk. A well-known case of geese getting sucked into passenger jet engines occurred in 2009. The plane, piloted by Captain Sullenberger, made an emergency landing in the Hudson River. The incident was re-created in a movie titled Sully, which premiered in theatres in 2016 (Joseph, 2018). Landfills should be sited no closer than 10,000 feet from airports that have jet engines or 5,000 feet for smaller airports that only have propeller aircraft—unless landfill proponents can prove that birds will not be a problem (EPA, n.d.). Floodplains and Wetlands Floodplains and wetlands have location restrictions that must also be considered and avoided. Before citing a landfill, it must be demonstrated that the landfill will not impact water flowing in any nearby floodplains during the 100-year flood. Though commonly thought of as a flood that will only occur every 100 years, that is not the definition of a 100-year flood. A 100-year flood is a flood that has a 1% or greater probability of occurring each year (Criteria for Municipal Solid Waste, 1991). A given location will likely have many more than one 100-year flood in a 100-year period.

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Wetlands, as shown in Figure 1, have water in them year-round and support a variety of waterfowl and habitats that offer a special benefit to ecosystems. Wetlands have special protections under the federal Clean Water Act (CWA). Any landfill cannot impact a wetland.

Faults, Seismic Zones, and Unstable Areas Additional items that must be given specific consideration for municipal solid waste landfills include shifting tectonic plates and unstable topography. A landfill must be at least 200 feet away from a seismic fault and cannot be located within a seismic impact zone. A seismic impact zone has experienced notable movement in the last 250 years. Unstable areas offer poor land for the support of a landfill foundation. During construction, operation, or after landfill closure, the geology/topography must be stable to avoid landfill movement. Figure 2 shows the failure of a landfill. Due to poor drainage and steep slopes, a large rainfall initiated the slope failure (Huvaj-Sarihan & Stark, 2008).

Figure 1. Wetlands (EPA, 2018)

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Operating Criteria for Municipal Solid Waste Landfills RCRA instituted important operational requirements for municipal solid waste landfills. First of all, municipal solid waste landfill staff must be educated regarding the types of materials that the landfill can accept. Hazardous materials are not acceptable; there is hazardous waste (HW) landfills. Hazardous waste landfills are sited and designed even more stringently than municipal solid waste landfills and can accept hazardous wastes. In addition to staff training, municipal solid waste landfills require daily soil cover as well as control of disease vectors, gases, leachate, and rainfall run-on or runoff. Daily Cover One of the most beneficial advances in landfill operation is the least technical. It is simply the act of depositing 6 inches of soil over each day's solid waste. This simple act of daily earthmoving is an RCRA requirement. Daily cover reduces the chance of fires and reduces odors and blowing materials. It also keeps rodents and birds from scavenging the waste, thus preventing offsite migration of litter and disease vectors. Explosive Gas Monitoring Over time, landfills become anaerobic. As discussed in previous units, anaerobic reactions produce methane. Methane is a flammable gas. 40 C.F.R. 258.23 requires that gas detection methods be installed so that methane does not reach flammable levels within the landfill and at the property boundary. Typically, gas monitoring wells are installed within the landfill and outside the landfill with regular sampling to satisfy requirements. Surface Water RCRA, as codified in 40 C.F.R. 258.27, describes requirements for surface water control. Landfill runoff cannot violate CWA standards. In other words, landfill runoff cannot pollute waterways. This is usually accomplished by diversion channels that catch rainfall and divert it off of the landfill. Most landfills are designed to minimize the amount of rainfall that infiltrates into the landfill. The more water that infiltrates, the more leachate that is produced. Leachate processing is expensive.

Figure 2. Failure of Hiriya Landfill in Israel in 1997 (Isenberg, 2003)

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Design Criteria As mentioned previously, 40 C.F.R. 258 lists minimum requirements for landfills. States are required to equal or exceed the federal requirements. 40 C.F.R. 258.40 describes landfill liner design requirements. The liner is installed along the bottom and sides of the landfill. The liner must consist of a flexible membrane (i.e., plastic) liner on top of a compacted soil liner (Criteria for Municipal Solid Waste, 1991). Most landfills use high-density polyethylene (HDPE) as the flexible membrane liner. This must be at least 60 mils thick (i.e., 0.06 inch). The compacted soil liner must have a hydraulic conductivity no greater than 10-7 centimeters per second (cm/s). Hydraulic conductivity is a measure of the permeability of the material. 10-7 cm/s is very low. The amount of water that can flow through soil is proportional to both the hydraulic conductivity and the water pressure acting on the soil. As water pressure increases, liquid flow increases through the soil. RCRA has a limit of 30 cm as the maximum water depth that is allowed to accumulate above the liner. This results in essentially no liquid leakage out of the landfill due to the low head pressure (30 cm) and the low hydraulic conductivity (Criteria for Municipal Solid Waste, 1991). Figure 3 shows the liner system. In the figure, CCL is an abbreviation for composite clay liner. This composite clay liner consists of the compacted soil previously described as having permeability no greater than 10-7 cm/s and at least 0.6 m (2 ft) thick. GM stands for geomembrane, which is the flexible membrane liner described above. The leachate collection and removal system (LCRS) is installed above the geomembrane, which typically consists of perforated pipes surrounded by gravel. These pipes convey liquid out of the landfill so that no more than 30 cm of water can pond above the liner.

Groundwater Monitoring Groundwater monitoring is essential to ensure that there is minimal groundwater or surface water impact on aquifers or the subsurface in general. Groundwater monitoring wells must be installed in the landfill to determine that liquid never exceeds 30 cm above the landfill liner. Groundwater monitoring wells must be installed outside of the landfill to measure groundwater chemical concentrations to ensure that they do not exceed regulatory levels (Worrell et al., 2017). Landfill Closure When landfills have reached the end of their useful life, they are capped. The cap's purpose is to minimize infiltration into the landfill and to minimize erosion of the cap. The cap consists of a liner no more permeable than the bottom composite soil liner. The cap liner is overlain by 18 inches of earthen material and then has at

Figure 3. Municipal solid waste landfill liner (EPA, 2004)

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least 6 inches of soil amenable to plant growth on the top. After the landfill closes, it must be monitored for 30 more years. This includes gas and leachate quantity and quality monitoring. If the integrity of the capping system deteriorates, then it must be repaired (Criteria for Municipal Solid Waste, 1991).

Conclusion The Unit VII Lesson focused on municipal solid waste landfill siting, design, and operational best practices. The RCRA addressed municipal solid waste requirements. The EPA’s requirements were codified in Title 40, Part 258, of the Code of Federal Regulations. The regulations addressed in this lesson included landfill location restrictions, operating criteria, design criteria, groundwater monitoring, and landfill closure.

References Criteria for Municipal Solid Waste, 40 C.F.R. § 258 (1991). https://www.ecfr.gov/cgi-

bin/retrieveECFR?gp=&SID=c94567294dff611654af7a3944a91d69&mc=true&r=PART&n=pt40.27.258 Huvaj-Sarihan, N., & Stark, T. D. (2008, August 14). Back-analyses of landfill slope failures [Paper

presentation]. Sixth International Conference on Case Histories in Geotechnical Engineering, Urbana, IL, United States. https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=2708&context=icchge

Isenberg, R. H. (2003, February 27). Landfill & waste geotechnical stability [PowerPoint presentation]. USEPA

Bioreactor Workshop, Reston, VA, United States. https://archive.epa.gov/epawaste/nonhaz/municipal/web/pdf/isenberg.pdf

Joseph, E. (2018, October 18). Movie review: "Sully" a win amongst suspense-craving movie goers.

https://link.gale.com/apps/doc/A559299116/AONE?u=oran95108&sid=AONE&xid=7a7ca056 U.S. Environmental Protection Agency. (n.d.). Ohio uses wetlands program development grants to protect

wetlands. https://www.epa.gov/wetlands/ohio-uses-wetlands-program-development-grants-protect- wetlands

U.S. Environmental Protection Agency. (2004, June). Survey of technologies for monitoring containment liners

and covers (EPA Publication No. 542-R-04-013). https://clu-in.org/download/char/epa542r04013.pdf Worrell, W. A., Vesilind, P. A., & Ludwig, C. (2017). Solid waste engineering: A global perspective (3rd ed.).

Cengage Learning. https://bookshelf.vitalsource.com/#/books/9781305888357

Suggested Unit Resources In order to access the following resources, click the links below. To learn more about landfill requirements listed in the Code of Federal Regulations, review the following resource. Criteria for Municipal Solid Waste Landfills, 40 C.F.R. § 258 (1991). https://www.ecfr.gov/cgi-

bin/retrieveECFR?gp=&SID=c94567294dff611654af7a3944a91d69&mc=true&r=PART&n=pt40.27.258 To learn more about landfill design and monitoring, review the resource below. U.S. Environmental Protection Agency. (2004, June). Survey of technologies for monitoring containment

liners and covers (EPA Publication No. 542-R-04-013). https://clu- in.org/download/char/epa542r04013.pdf