Disposal of contaminated sediments/soils in MSW landfills: Need to consider the true cost

A disturbing trend among governmental agencies is the remediation of so‐called “nonhazardous” contaminated sediments/soils by deposition in minimum‐design Subtitle D municipal solid waste (MSW) landfills or landfills with equivalent design. This is done despite the fact that, in terms of protection of public health and environmental quality, the designation “nonhazardous” is misleading at best, and the fact that minimum‐design Subtitle D landfills as being allowed will not ensure protection of groundwater quality for as long as the buried wastes remain a threat. Although acknowledged in the regulatory documentation and exposed in the writings of a few in the scientific/engineering community, the environmental and public health issues that will inevitably be faced at minimum‐design Subtitle D landfills are underplayed, and even misrepresented, to the public. Discussion of relevant issues, as well as remarkable omissions, characterized the October 2004 United States Army Corps of Engineers (US ACE)/United States Environmental Protection Agency (US EPA)/Sediment Management Work Group (SMWG) conference,” Addressing Uncertainty and Managing Risk at Contaminated Sediment Sites.” This article addresses many of those neglected issues. © 2005 Wiley Periodicals, Inc.     

Washing of waste prior to landfilling

The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment.     

CCA-treated wood disposed in landfills and life-cycle trade-offs with waste-to-energy and MSW landfill disposal

Chromated copper arsenate (CCA)-treated wood is a preservative treated wood construction product that grew in use in the 1970s for both residential and industrial applications. Although some countries have banned the use of the product for some applications, others have not, and the product continues to enter the waste stream from construction, demolition and remodeling projects. CCA-treated wood as a solid waste is managed in various ways throughout the world. In the US, CCA-treated wood is disposed primarily within landfills; however some of the wood is combusted in waste-to-energy (WTE) facilities. In other countries, the predominant disposal option for wood, sometimes including CCA-treated wood, is combustion for the production of energy. This paper presents an estimate of the quantity of CCA-treated wood entering the disposal stream in the US, as well as an examination of the trade-offs between landfilling and WTE combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). Based upon production statistics, the estimated life span and the phaseout of CCA-treated wood, recent disposal projections estimate the peak US disposal rate to occur in 2008, at 9.7 million m(3). CCA-treated wood, when disposed with construction and demolition (C&D) debris and municipal solid waste (MSW), has been found to increase arsenic and chromium concentrations in leachate. For this reason, and because MSW landfills are lined, MSW landfills have been recommended as a preferred disposal option over unlined C&D debris landfills. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with US Environmental Protection Agency (US EPA) regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash in the WTE scenario, the MSW landfill scenario releases a greater amount of arsenic from leachate in a more dilute form. The WTE scenario releases more chromium from the ash on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase leachate management costs.     

Leaching behaviour of hazardous demolition waste

Demolition wastes are generally disposed of in unlined landfills for inert waste. However, demolition wastes are not just inert wastes. Indeed, a small fraction of demolition waste contains components that are hazardous to human health and the environment, e.g., lead-based paint, mercury-contained in fluorescent lamps, treated wood, and asbestos. The objective of this study is to evaluate the release potential of pollutants contained in these hazardous components when they are mixed with inert wastes in unlined landfills. After identification of the different building products which can contain hazardous elements and which can be potentially pollutant in landfill scenario, we performed leaching tests using three different lysimeters: one lysimeter containing only inert wastes and two lysimeters containing inert wastes mixed with hazardous demolition wastes. The leachates from these lysimeters were analysed (heavy metals, chlorides, sulphates fluoride, DOC (Dissolved Organic Carbon), phenol index, and PAH). Finally, we compared concentrations and cumulative releases of elements in leachates with the limits values of European regulation for the acceptance of inert wastes at landfill. Results indicate that limit values are exceeded for some elements. We also performed a percolation column test with only demolition hazardous wastes to evaluate the specific contribution of these wastes in the observed releases.     

Perpetual landfilling through aeration of the waste mass; lessons from test cells in Georgia (USA).

Municipal solid waste (MSW) landfills worldwide are experiencing the consequences of conventional landfilling techniques, whereby anaerobic conditions are created within the landfilled waste. Under anaerobic conditions within a landfill site slow stabilization of the waste mass occurs, producing methane, (an explosive 'green house' gas) and leachate (which can pollute groundwater) over long periods of time. As a potential solution, it was demonstrated that the aerobic degradation of MSW within a landfill can significantly increase the rate of waste decomposition and settlement, decrease the methane production and leachate leaving the system, and potentially increase the operational life of the site. Readily integrated into the existing landfill infrastructure, this approach can safely and cost-effectively convert a MSW landfill from anaerobic to aerobic degradation processes, thereby effectively composting much of the organic portions (one of the potentially polluting elements in a conventional landfill site) of the waste. This paper summarizes the successful results of two separate aerobic landfill projects located in Georgia (USA) and discusses the potential economic and environmental impacts to worldwide solid waste management practices.     

The active role of state laws in superfund cleanups

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) did not ignore the fifty individual states when establishing responsibility, authority, and liability for cleaning up hazardous waste sites. Although CERCLA gives EPA the ultimate authority to select a remedy for a contaminated site, the law was drafted not only to allow for state activity without EPA, but also for significant state input when EPA is involved. The relationship between a state (and its environmental laws) and EPA can help decide the remedial and financial interests of any potentially responsible party (PRP). This article discusses the relevant CERCLA provisions, recent court decisions, and resolved and unresolved issues in federal-state Superfund involvement, and recommends several common-sense strategies for PRPs when working with a state in a Superfund cleanup.     

Landfills in Jiangsu province, China, and potential threats for public health: leachate appraisal and spatial analysis using geographic information system and remote sensing

Waste disposal is of growing environmental and public health concern in China where landfilling is the predominant method of disposal. The assessment of potential health hazards posed by existing landfills requires sound information, and processing of a significant amount of spatial data. Geographical information system (GIS) and remote sensing (RS) are valuable tools for assessing health impacts due to landfills. The aims of this study were: (i) to analyze the leachate and gas emissions from landfills used for domestic waste disposal in a metropolitan area of Jiangsu province, China, (ii) to investigate remotely-sensed environmental features in close proximity to landfills, and (iii) to evaluate the compliance of their location and leachate quality with the relevant national regulations. We randomly selected five landfills in the metropolitan areas of Wuxi and Suzhou city, Jiangsu province, established a GIS database and examined whether data were in compliance with national environmental and public health regulations. The leachates of the sampled landfills contained heavy metals (Pb, As, Cr(6+) and Hg) and organic compounds in concentrations considered harmful to human health. Measured methane concentrations on landfill surfaces were low. Spatial analysis of the location of landfills with regard to distance from major water bodies, sensible infrastructure and environmental conditions according to current national legislation resulted in the rejection of four of the five sites as inappropriate for landfills. Our results call for rigorous evaluation of the spatial location of landfills in China that must take into consideration environmental and public health criteria.     

LCA comparison of windrow composting of yard wastes with use as alternative daily cover (ADC)

This study compared the environmental impacts of composting yard wastes in windrows with using them in place of soil as alternative daily cover (ADC) in landfills. The Life Cycle Assessment was made using the SimaPro LCA software and showed that the ADC scenario is more beneficial for the environment than windrow composting. ADC use is also a less costly means of disposal of yard wastes. This finding applies only in cases where there are sanitary landfills in the area that are equipped with gas collection systems and can use yard wastes as alternative daily cover. Otherwise, the environmentally preferable method for disposal of source-separated yard wastes is composting rather than landfilling.     

Probabilistic approach for estimating the release of contaminants under field management scenarios

A probabilistic approach is presented for estimating the release of contaminants by leaching, when wastes are being considered for disposal in a class of landfills but the specific landfill disposal site is uncertain. A simple percolation and equilibrium-based release model is used in conjunction with laboratory testing results and observations of field leachate characteristics for municipal solid waste landfills, hazardous waste landfills and industrial co-disposal landfills. The approach is applied for assessing the efficacy of potential treatment processes for mercury contaminated soils. For each landfill scenario, historical values of leachate pH and annual leachate generation quantities were used to derive the probability distribution functions of the field pH and LS ratio that may be expected to contact the disposed material over an estimated time period of 100 years. For each potential treatment process, laboratory testing was used to establish the treated material's leaching characteristics as a function of pH LS ratio. This approach allowed determination of distribution frequencies and limit values for release estimates instead of single point estimates. The probability of the mass of a constituent of interest released exceeding a hypothetical threshold was examined for each treatment process and landfill system. Results of the probabilistic analysis allowed for integration of a range of data and provided a good basis for assessing the efficacy of the examined treatment processes over the three assumed disposal scenarios.     

Correlation between physicochemical and ecotoxicological approaches to estimate landfill leachates toxicity

Leachates from municipal solid waste (MSW) landfills may contain a huge diversity of contaminants; these wastewaters should be considered as potentially hazardous complex mixtures, representing a potential environmental risk for surface and groundwater. Current MSW landfill wastes regulatory approaches deem exclusively on the physicochemical characterization and does not contemplate the ecotoxicological assessment of landfill leachates. However, the presence of highly toxic substances in consumer products requires reconsideration on the need of more specific ecotoxicological assessments. The main aim of this study was to evaluate the toxicity of different MSW landfill leachates using a battery of toxicity tests including acute toxicity tests with Daphnia magna and the anuran Xenopus laevis and the in vitro toxicity test with the fish cell line RTG-2. The additional objective was to study the possible correlation between physicochemical properties and the toxicity results obtained for untreated landfill leachates. The results showed that the proposed test battery was effective for the ecotoxicological characterization of MSW landfill leachates. A moderate to strong correlation between the measured physicochemical parameters and the calculated toxicity units was detected for all toxicity assays. Correlation factors of 0.85, 0.86 and 0.55 for Daphnia, Xenopus and RTG-2 tests, respectively, were found. The discriminant analysis showed that certain physicochemical parameters could be used for an initial categorization of the potential aquatic acute toxicity of leachates; this finding may facilitate leachates management as the physicochemical characterization is currently the most common or even only monitoring method employed in a large majority of landfills. Ammonia, alkalinity and chemical oxygen demand (COD), together with chloride, allowed a proper categorization of leachates toxicity for up to 75% of tested samples, with a small percentage of false negatives.     

Understanding the RCRA corrective action process

The Resource Conservation and Recovery Act (RCRA) was enacted in 1976. The Hazardous and Solid Waste Amendments (HSWA) of 1984 specify “corrective action” requirements for protecting human health and the environment from environmental contamination at active hazardous waste treatment, storage, and disposal facilities. RCRA and its corrective action requirements are designed to prevent the creation of new Superfund sites by regulating and remediating active facilities. The RCRA corrective action process has four basic components: the facility assessment, facility investigation, corrective measures study, and corrective measures implementation. This article presents an overview of the RCRA corrective action process and presents four case studies from three U.S. EPA regions.     

Landfill modelling in LCA - a contribution based on empirical data

Landfills at various stages of development, depending on their age and location, can be found throughout Europe. The type of facilities goes from uncontrolled dumpsites to highly engineered facilities with leachate and gas management. In addition, some landfills are designed to receive untreated waste, while others can receive incineration residues (MSWI) or residues after mechanical biological treatment (MBT). Dimension, type and duration of the emissions from landfills depend on the quality of the disposed waste, the technical design, and the location of the landfill. Environmental impacts are produced by the leachate (heavy metals, organic loading), emissions into the air (CH(4), hydrocarbons, halogenated hydrocarbons) and from the energy or fuel requirements for the operation of the landfill (SO(2) and NO(x) from the production of electricity from fossil fuels). To include landfilling in an life-cycle assessment (LCA) approach entails several methodological questions (multi-input process, site-specific influence, time dependency). Additionally, no experiences are available with regard to mid-term behaviour (decades) for the relatively new types of landfill (MBT landfill, landfill for residues from MSWI). The present paper focuses on two main issues concerning modelling of landfills in LCA: Firstly, it is an acknowledged fact that emissions from landfills may prevail for a very long time, often thousands of years or longer. The choice of time frame in the LCA of landfilling may therefore clearly affect the results. Secondly, the reliability of results obtained through a life-cycle assessment depends on the availability and quality of Life Cycle Inventory (LCI) data. Therefore the choice of the general approach, using multi-input inventory tool versus empirical results, may also influence the results. In this paper the different approaches concerning time horizon and LCI will be introduced and discussed. In the application of empirical results, the presence of data gaps may limit the inclusion of several impact categories and therefore affect the results obtained by the study. For this reason, every effort has been made to provide high-quality empirical LCI data for landfills in Central Europe.     

Estimating the costs of corrective action at land disposal facilities

The U.S. Environmental Protection Agency (EPA) has proposed regulations that would require corrective action (e.g., soil excavation and groundwater removal and treatment) at municipal solid waste landfills (MSWLFs) and hazardous waste treatment, storage, and disposal facilities (TSDFs). This paper presents an overview of the proposed corrective action regulations, and discusses their relationship to proposed or existing closure and post-closure care regulations. The paper then presents estimated corrective action cost curves for various MSWLF scenarios defined by landfill area, average waste thickness, and the presence or absence of a clay liner. The paper finally illustrates the economic benefits of sound closure and postclosure care by comparing estimated costs of corrective action to estimated costs of closure and postclosure care at MSWLFs.     

Pricing landfill externalities: emissions and disamenity costs in Cape Town, South Africa

The external (environmental and social) costs of landfilling (e.g. emissions to air, soil and water; and 'disamenities' such as odours and pests) are difficult to quantify in monetary terms, and are therefore not generally reflected in waste disposal charges or taken into account in decision making regarding waste management options. This results in a bias against alternatives such as recycling, which may be more expensive than landfilling from a purely financial perspective, but preferable from an environmental and social perspective. There is therefore a need to quantify external costs in monetary terms, so that different disposal options can be compared on the basis of their overall costs to society (financial plus external costs). This study attempts to estimate the external costs of landfilling in the City of Cape Town for different scenarios, using the benefits transfer method (for emissions) and the hedonic pricing method (for disamenities). Both methods (in particular the process of transferring and adjusting estimates from one study site to another) are described in detail, allowing the procedures to be replicated elsewhere. The results show that external costs are currently R111 (in South African Rands, or approximately US$16) per tonne of waste, although these could decline under a scenario in which energy is recovered, or in which the existing urban landfills are replaced with a new regional landfill.     

Current and future solid waste management system in Northern Viet Nam with focus on Ha Noi: climate change effects and landfill management

The contribution investigates the solid waste management system in Ha Noi under consideration of the interrelation between climate change effects and landfill management by means of a cause-and-effect-analysis as well as water balances using the HELP 3.95 model and gas emission data, followed by a Strength, Weakness, Opportunities, Threats (SWOT) analysis. Even landfills are sources of methane (CH₄) emissions they are also impacted by climate change. The main effects on landfill sites are the change of climatic conditions, namely the regional water balance, extreme precipitation and storm events. The results of the water balance model results show that a geomembrane surface sealing can reduce the leachate formation significantly, a fact that is also valid for the climate change scenario with higher precipitation. The risk of flooding and erosion at the landfill sites increases, which will require a customized water management. In parallel landfill gas offers the opportunity for recovery of Greenhouse Gases (GHG) and the generation of renewable energy. Some further management options are wind turbines, photovoltaic systems or biomass for biogas conversion, which was grown on closed landfill sites. The inclusion of climate friendly management options of closed landfills in a “Good Landfill Aftercare Practice” is recommended.     

Innovative reuse of drinking water sludge in geo-environmental applications

In recent years, the replacement of natural raw materials with new alternative materials, which acquire an economic, energetic and environmental value, has gained increasing importance. The considerable consumption of water has favoured the increase in the number of drinking water treatment plants and, consequently, the production of drinking water sludge. This paper proposes a protocol of analyses capable of evaluating chemical characteristics of drinking water sludge from surface water treatment plants. Thereby we are able to assess their possible beneficial use for geo-environmental applications, such as the construction of barrier layers for landfill and for the formation of “bio-soils”, when mixed with the stabilized organic fraction of municipal solid waste. This paper reports the results of a study aimed at evaluating the quality and environmental aspects of reconstructed soils (“bio-soil”), which are used in much greater quantities than the usual standard, for “massive” applications in environmental actions such as the final cover of landfills. The granulometric, chemical and physical analyses of the sludge and the leaching test on the stabilized organic fraction showed the suitability of the proposed materials for reuse.The study proved that the reuse of drinking water sludge for the construction of barrier layers and the formation of “bio-soils” reduces the consumption of natural materials, the demand for landfill volumes, and offers numerous technological advantages.     

Assessment of the state of food waste treatment in the United States and Canada

Currently in the US, over 97% of food waste is estimated to be buried in landfills. There is nonetheless interest in strategies to divert this waste from landfills as evidenced by a number of programs and policies at the local and state levels, including collection programs for source separated organic wastes (SSO). The objective of this study was to characterize the state-of-the-practice of food waste treatment alternatives in the US and Canada. Site visits were conducted to aerobic composting and two anaerobic digestion facilities, in addition to meetings with officials that are responsible for program implementation and financing. The technology to produce useful products from either aerobic or anaerobic treatment of SSO is in place. However, there are a number of implementation issues that must be addressed, principally project economics and feedstock purity. Project economics varied by region based on landfill disposal fees. Feedstock purity can be obtained by enforcement of contaminant standards and/or manual or mechanical sorting of the feedstock prior to and after treatment. Future SSO diversion will be governed by economics and policy incentives, including landfill organics bans and climate change mitigation policies.     

Unreliability of co‐occurrence‐based sediment quality guidelines for contaminated sediment evaluations at Superfund/hazardous chemical sites

Many Superfund/hazardous chemical sites include waterbodies whose sediments contain hazardous chemicals. With the need to assess, rank, and remediate contaminated sediments at such sites, as well as in other waterways, regulators seek a simple, quantitative assessment approach that feeds easily into a decision‐making scheme. Numeric, co‐occurrence‐based “sediment quality guidelines” have emerged with the appearance of administrative simplicity. However, the very foundation of the co‐occurrence approach, based on the total concentrations of a chemical(s) in sediment, is technically invalid; its application relies on additional technically invalid presumptions. Use of technically invalid evaluation approaches renders any assessment of the significance of sediment contamination unreliable. This article reviews the technical roots and assumptions of the co‐occurrence‐based SQGs, the fundamental flaws in the rationale behind their development and application, and their misapplication for sediment quality evaluation. It also reviews concepts and approaches for the more reliable evaluation, ranking, and cleanup assessment of contaminated sediments at Superfund sites and elsewhere. © 2005 Wiley Periodicals, Inc.     

Assessment and analysis of industrial liquid waste and sludge disposal at unlined landfill sites in arid climate

Municipal solid waste disposal sites in arid countries such as Kuwait receive various types of waste materials like sewage sludge, chemical waste and other debris. Large amounts of leachate are expected to be generated due to the improper disposal of industrial wastewater, sewage sludge and chemical wastes with municipal solid waste at landfill sites even though the rainwater is scarce. Almost 95% of all solid waste generated in Kuwait during the last 10 years was dumped in five unlined landfills. The sites accepting liquid waste consist of old sand quarries that do not follow any specific engineering guidelines. With the current practice, contamination of the ground water table is possible due to the close location of the water table beneath the bottom of the waste disposal sites. This study determined the percentage of industrial liquid waste and sludge of the total waste dumped at the landfill sites, analyzed the chemical characteristics of liquid waste stream and contaminated water at disposal sites, and finally evaluated the possible risk posed by the continuous dumping of such wastes at the unlined landfills. Statistical analysis has been performed on the disposal and characterization of industrial wastewater and sludge at five active landfill sites. The chemical analysis shows that all the industrial wastes and sludge have high concentrations of COD, suspended solids, and heavy metals. Results show that from 1993 to 2000, 5.14+/-1.13 million t of total wastes were disposed per year in all active landfill sites in Kuwait. The share of industrial liquid and sludge waste was 1.85+/-0.19 million t representing 37.22+/-6.85% of total waste disposed in all landfill sites. Such wastes contribute to landfill leachate which pollutes groundwater and may enter the food chain causing adverse health effects. Lined evaporation ponds are suggested as an economical and safe solution for industrial wastewater and sludge disposal in the arid climate of Kuwait.     

The use of LCA in selecting the best MSW management system

This paper focuses on the study of eleven environmental impact categories produced by several municipal solid waste management systems (scenarios) operating on a provincial scale in Southern Italy. In particular, the analysis takes into account 12 management scenarios with 16 management phases for each one. The only difference among ten of the scenarios (separated kerbside collection of all recyclables, glass excepted, composting of putrescibles, RDF pressed bales production and incineration, final landfilling) is the percentage of separated collection varying in the range of 35–80%, while the other two scenarios, for 80% of separate collection, consider different alternatives in the disposal of treatment residues (dry residue sorting and final landfilling or direct disposal in landfill). The potential impacts induced on the environmental components were analysed using the life cycle assessment (LCA) procedure called “WISARD” (Waste Integrated System Assessment for Recovery and Disposal). Paper recycling was the phase with the greatest influence on avoided impacts, while the collection logistics of dry residue was the phase with the greatest influence on produced impacts. For six impact categories (renewable and total energy use, water, suspended solids and oxydable matters index, eutrophication and hazardous waste production), for high percentages of separate collection a management system based on recovery and recycling but without incineration would be preferable.