**2.1 Environmental impacts**

### **2.1.1 Impacts of Landfills on water, land, and air**

Environmental impacts from landfills, principally caused by leachate generation and gas production, include air emissions, climate change, groundwater pollution by leachate, and relevant nuisance issues (i.e. odor, litter, vectors, and dust) (Hanson & Caponi, 2009).

When landfills consisted mainly of excavated pits, the waste would come directly into contact with and contaminate the surrounding surface and groundwater. During a precipitation event, water percolates through the landfill system creating leachate, which is highly contaminated wastewater. The composition of leachate can be categorized into four main groups: dissolved organic matters (mainly volatile fatty acids or humic-like substances); inorganic macrocomponents such as calcium, magnesium, sodium, potassium, ammonium, iron, magnesium, chloride, sulfate, and hydrogen carbonate; heavy metals like cadmium, chromium, copper, lead, nickel, and zinc; and xenobiotic organic compounds such as chlorinated organics, phenols, and pesticides (Kjeldsen et al, 2002; Renou et al, 2008). The surface runoff creates gullies and erosion, washing debris, contaminants, and sediment into nearby surface water bodies (Duffy, 2008). Landfill leachate harms surface water bodies by depleting dissolved oxygen (DO) and increasing ammonia levels altering the flora and fauna of the water body (Kjedsen et al, 2002).

Air pollution is caused via two routes, the open burning of garbage and the anaerobic degradation of the organic fraction in solid waste. The open burning of garbage creates smoke, polluting the air and producing open debris. The natural, anaerobic decomposition by microorganisms transforms the waste organic fraction into methane and carbon dioxide, which are two primary greenhouse gases (Hanson & Caponi, 2009) and may kill the surrounding vegetation. The decomposition rate and amount of gas production depend heavily on the temperature and precipitation of the area (Duffy, 2008). Methane is a potent greenhouse gas that is 23 more time potent than carbon dioxide. Even though landfills are not the leading source of greenhouse gas production, they are the primary contributor to anthropogenically produced methane. (Hanson & Caponi, 2009) Volatile organic compounds (VOCs) are also released into the air directly from the products themselves such as cleaning fluids (NSWMA, n.d).

The produced gas and generated leachate from landfills must be properly collected and treated before they move offsite and further affect environmental and human health (NSWMA, n.d.) Of note, the leachate generated from the landfill bridges solid waste with the hydrosphere (particularly groundwater) and lithosphere (i.e. soil), while the landfill gases connect solid wastes to the atmosphere. Therefore, it is vital to understand that landfill engineered sites have a potential to pollute more than one of the Earth's spheres.

#### **2.1.2 Decomposition of solid waste in landfills**

150 Management of Organic Waste

As the human population, along with the industrial, municipal, and commercial sectors, continues to grow exponentially, the amount of waste generated will significantly increase over the years (Renou et al, 2008). The number of municipal landfills and amount of waste landfilled have declined combined with an increase in recycling and composting rates over the past 40 years in the United States (EPA, 2010). However, the majority of waste is already located in landfills (Environmental Industry Association, 2011) and landfills are still the most common form of waste disposal in the United States (EPA, 2010). As of 2003, approximately 21.3 years of landfill capacity remained in the United States, and less than ten

Environmental impacts from landfills, principally caused by leachate generation and gas production, include air emissions, climate change, groundwater pollution by leachate, and

When landfills consisted mainly of excavated pits, the waste would come directly into contact with and contaminate the surrounding surface and groundwater. During a precipitation event, water percolates through the landfill system creating leachate, which is highly contaminated wastewater. The composition of leachate can be categorized into four main groups: dissolved organic matters (mainly volatile fatty acids or humic-like substances); inorganic macrocomponents such as calcium, magnesium, sodium, potassium, ammonium, iron, magnesium, chloride, sulfate, and hydrogen carbonate; heavy metals like cadmium, chromium, copper, lead, nickel, and zinc; and xenobiotic organic compounds such as chlorinated organics, phenols, and pesticides (Kjeldsen et al, 2002; Renou et al, 2008). The surface runoff creates gullies and erosion, washing debris, contaminants, and sediment into nearby surface water bodies (Duffy, 2008). Landfill leachate harms surface water bodies by depleting dissolved oxygen (DO) and increasing ammonia levels altering

Air pollution is caused via two routes, the open burning of garbage and the anaerobic degradation of the organic fraction in solid waste. The open burning of garbage creates smoke, polluting the air and producing open debris. The natural, anaerobic decomposition by microorganisms transforms the waste organic fraction into methane and carbon dioxide, which are two primary greenhouse gases (Hanson & Caponi, 2009) and may kill the surrounding vegetation. The decomposition rate and amount of gas production depend heavily on the temperature and precipitation of the area (Duffy, 2008). Methane is a potent greenhouse gas that is 23 more time potent than carbon dioxide. Even though landfills are not the leading source of greenhouse gas production, they are the primary contributor to anthropogenically produced methane. (Hanson & Caponi, 2009) Volatile organic compounds (VOCs) are also released into the air directly from the products themselves such

The produced gas and generated leachate from landfills must be properly collected and treated before they move offsite and further affect environmental and human health (NSWMA, n.d.) Of note, the leachate generated from the landfill bridges solid waste with

relevant nuisance issues (i.e. odor, litter, vectors, and dust) (Hanson & Caponi, 2009).

years of capacity left in New Jersey (Hansen & Caponi, 2009).

**2.1.1 Impacts of Landfills on water, land, and air** 

the flora and fauna of the water body (Kjedsen et al, 2002).

as cleaning fluids (NSWMA, n.d).

**2. Background** 

**2.1 Environmental impacts** 

Typically, solid waste within landfills undergoes four stages of decomposition: an initial aerobic phase, an anaerobic acid phase, an initial methanogenic phase, and a stable methanogenic phase. The initial aerobic phase lasts only the first couple of days as oxygen in the voids is quickly depleted without any replenishment when the waste is covered. Therefore, an aerobic biodegradation of organic fraction of solid waste solely occur during a very short period, in which carbon dioxide is produced as a product and the temperature of the waste is increased. Leachate produced during this phase comes from direct precipitation or released from the moisture content of the waste itself (Kjeldsen et al, 2002). With the depletion of oxygen, the landfills quickly become anaerobic, and aerobic microbes dominate within the landfills, allowing fermentation to take place. Therefore, in the following anaerobic acid phase, the complex organic molecules are mostly degraded to volatile fatty acids, leading to a pH decrease. The initial methanogenic phase begins when methanogenic microorganisms grow in the waste, further transforming the volatile fatty acids to methane and carbon dioxide (Renou et al, 2008). The consumption of the organic acids raises the pH of the waste. During the stable methanogenic phase, the pH continues to increase. Methane production peaks and then declines as the amount of soluble materials decreases. The remaining waste is mainly refractory, non-biodegradable compounds like humic-like substances. The overall decomposition rates can be accelerated by a high moisture content and an initial aeration of the waste (Kjeldsen et al, 2002).

During different organic waste decomposition phases, landfill leachate and landfill gases may exhibit different characteristics. When volatile organic compounds dominate in the acid phase, leachate pH is typically at 3.0-4.0, under which heavy metals, such as calcium, magnesium, iron, and manganese, largely exist in leachate. Meanwhile, a huge number of biodegradable organic compounds are present in leachate, and 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) may reach a few tens of thousands of mg/L. And the organics are highly biodegradable characterized by a high BOD5/COD (typically > 0.6). However, with the further decomposition into methangoenic phase and subsequent reduction in the concentration of organic acids, the leachate pH is raised to a neutral range, and the leachate organic content is significantly reduced. COD may drop to a few hundreds or thousands of mg/L, and the organic compounds are refractory with a low BOD5/COD (typically < 0.3). And the concentrations of heavy metals in leachate greatly decrease as a result of precipitation more readily occurring at a high pH. When the landfill condition transform from aerobic to anaerobic condition, sulfate may be microbiologically reduced to hydrogen sulfide, so that the sulfate level is decreased with the landfilling time. Chloride, sodium, and potassium do not show a significant change in their concentrations throughout the decomposition, thus exhibiting an inert behavior. Ammonia-nitrogen concentrations remain high during all phases of decomposition, and thought to be the largest issue in landfill management for the long term. In leachate, monoaromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, and xylenes) and halogenated hydrocarbons are the most common xenabiotic organic compounds found. They are relatively recalcitrant. The concentrations of xenabiotic organic compounds vary broadly

Landfill Management and Remediation Practices in New Jersey, United States 153

layered above the leachate collection system, compacted, and covered daily to reduce odors, vectors, fires, and blowing litter. When the landfill reaches a permitted capacity and then is closed, a final cap is placed on the top of the landfill to prevent precipitation seeping through the waste. The final cap consists of a low permeability material such as clay or synthetic material (NSWMA, n.d.). Storm water channels are constructed on and around the landfill to direct rainwater to retention ponds for erosion control and reduce surface water contamination. Lastly, a long-term monitoring plan is implemented to ensure the liner and gas/leachate collection systems are operating properly, and the surrounding or underlying groundwater is not contaminated (Environmental Industry Association, 2011). Properly designed landfills can be inexpensive means of disposal (Hanson & Caponi, 2009), but many landfills are older, poorly designed and not managed, thus causing numerous

The Solid Waste Disposal Act of 1965 was the first regulation on waste disposal in the United States, and formed the national office of solid waste. Within the following 10 years, every state had regulations on the management of solid waste, varying from the banning of open burning to requiring permits and regulations on design and operational standards

The Resource Conservation and Recovery Act (RCRA), passed by Congress in 1976, and the RCRA Hazardous and Solid Waste Amendments in 1984 granted the US Environmental Protection Agency regulatory control over the disposal of waste (Hanson & Caponi, 2009). The program was implemented to assess the problems associated with an increasing amount of municipal and industrial wastes that the nation was confronted with. RCRA separated hazardous and non-hazardous waste and mandated the Environmental Protection Agency to create design, operational, locational, environmental monitoring standards, to close or upgrade existing landfills, and secure funding for long-term assessment of the

The solid waste program, under Subtitle D, requires states to create management plans, set criteria for solid waste, and restrict the use of open dumping. Subtitle D's regulations lead to the creation of larger, regional landfills and waste management companies, which improves environmental and economical integrity relative to the small, scattered dumps of the past. Larger waste management facilities are more cost effective in terms of capacity, volume, and operational resources (i.e. staff and equipment) to meet the increasing volume of waste

The Resource Conservation and Recovery Act addresses only active and future landfill sites, while the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), otherwise known as Superfund, focuses on abandoned or historical sites (EPA, 2011). The Environmental Protection Agency, through the Superfund program, holds the parties responsible for clean up or if no responsible party can be identified, the Agency uses money from a special trust fund. This program is a complex, long-term cleanup process involving assessment, placement on the National Priorities List (NPL), and implementation of appropriate cleanup plans (EPA, 2011). The National Priority List is a list of the sites

environmental impacts (NJDEP, 2006).

**3. Regulations** 

(NSWMA, n.d.).

landfill (NSWMA, n.d.).

(Duffy, 2008).

depending on the landfill, with respect to age and restrictions of dumping hazardous waste (Kjeldsen et al, 2002). Recently, some emerging leachate contaminants, such as perfluorinated chemicals, pharmaceuticals, and engineered nanomaterials, at trace levels have been paid special attention to. However, their fates in leachate are poorly understood. For landfill gases, oxygen and nitrogen gases predominate in the initial phase because they, trapped from air, are buried together with solid waste, reflecting the composition of air. However, carbon dioxide and methane will gradually take over as products of anaerobic degradation of organic wastes. VOCs and ammonia may be present in landfill gases. Particularly, ammonia-nitrogen exists in forms of ammonium ions and dissolved ammonia gas in leachate. During methanogenic phases, leachate pH is back to neutral and even basic, and the fraction of dissolved ammonia will be increased. Therefore, the content of ammonia in landfill gases will be relatively high at these phases, and it can be quantitatively analyzed using the Henry's law that governs the distribution of dissolved ammonia gas in leachate and ammonia gas in landfill gases.

#### **2.2 Landfill designs**

Almost everything humans do creates wastes. However, waste did not become a problem until humans left the nomadic lifestyle and starting living in communities. As the world population has increase and changed from a rural agrarian society to a urban industrial society, the disposal of waste has become more concentrated. Dumping trash in the middle of cities was common practice in the United States until scientists linked human health problems to sanitary conditions in the early 1800's. In the early 20th century North America, cities began to collect garbage and either incinerated it at a landfill or home, or placed it in an unlined landfill (NSWMA, n.d.; Duffy, 2008). One of the first landfills was created in California in 1935, which consisted of a hole in the ground occasionally covered with soil (NSWMA, n.d.). Dumps were usually small and scattered affecting many areas (Duffy, 2008). Approximately 85% of U.S. sanitary landfills are unlined (Pipkin et al, 2010) and many are not covered, coming into direct contact with and polluting the air, groundwater and soil. Open dump burning was a common practice to reduce the volume of waste and increase the remaining capacity. When a landfill was closed, soil of varying thickness and slopes were placed over the waste (Duffy, 2008).

After the passage of laws and regulations that banned open burning at dumps, waste was spread into layers and regularly compacted to reduce the total volume, increase stability, and extend the life of the landfill. Modern landfills are located, operated, designed, closed, and monitored to ensure that the environment is appropriately protected (Environmental Industry Association, 2011). Newer landfills are restricted from being built in floodplains, wetlands, fault zones, and seismic impact zones unless the landfills have structural integrity and protective measures in place to protect human and environmental health. Protective operational procedures include rejecting hazardous and bulk materials, non- containerized liquids, the restriction of open burning, securing site access, and keeping up-to-date records on groundwater, surface water, and air monitoring results. Landfills are now designed with leachate collection and liner systems to prevent the migration of leachate off-site. A liner of low permeability materials such as clay, geotextiles, or plastic, with a leachate collection and recovery system placed on top of the liner. The leachate collected are either treated on or offsite at a wastewater treatment plant, while the gases produced are burned or converted into energy (i.e. electricity, heat, steam, replacement of natural gas, or vehicle fuel). Waste is layered above the leachate collection system, compacted, and covered daily to reduce odors, vectors, fires, and blowing litter. When the landfill reaches a permitted capacity and then is closed, a final cap is placed on the top of the landfill to prevent precipitation seeping through the waste. The final cap consists of a low permeability material such as clay or synthetic material (NSWMA, n.d.). Storm water channels are constructed on and around the landfill to direct rainwater to retention ponds for erosion control and reduce surface water contamination. Lastly, a long-term monitoring plan is implemented to ensure the liner and gas/leachate collection systems are operating properly, and the surrounding or underlying groundwater is not contaminated (Environmental Industry Association, 2011). Properly designed landfills can be inexpensive means of disposal (Hanson & Caponi, 2009), but many landfills are older, poorly designed and not managed, thus causing numerous environmental impacts (NJDEP, 2006).
