Post-closure Care Research Articles

Evaluation of stabilization status of the landfill layers by comparing long-term monitoring data of methane emission with FOD model estimate

ABSTRACT Long-term monitoring and treatment of landfill leachate (LFL) and landfill gas (LFG) is required until landfilled municipal solid waste (MSW) is sufficiently stabilized and post-closure care can be terminated. Monitoring data of methane (CH4) emissions in LFG from a marine landfill over 30 years were compared with the IPCC first order decay (FOD) model estimates. The observed changes in CH4 showed a similar attenuation trend to the estimates, but the observed CH4 emissions were only about 30% of the estimate over 30 years; LFL is considered to be another pathway for organic carbon to be released to the environment, but the total organic carbon in discharged LFL was only about 0.2% of CH4 carbon in LFG emission over the same period. The increase in the CO2/CH4 ratio in LFG over time suggests that the discrepancy between estimated and observed emissions is due to methane oxidation in the overlying soil, in addition to the high coefficient values used in the FOD model. Total organic carbon (TOC) in LFL discharged as effluent reached a maximum value in the early stages of the landfill and gradually decreased, but only to about one-third of the maximum value after more than 30 years and a decrease in the amount of effluent. As incineration of MSW is expected to reduce organic carbon and nitrogen, the CH4 reduction effect of incineration of business and household waste and sewage sludge was investigated using FOD model estimates.

Impact of low temperature on ex situ nitritation/in situ denitritation in field pilot-scale landfill for postclosure care of leachate treatment and gas content.

Leachates and landfill gas (LFG) are the major problems for closed landfills (CL) and cause significant threats to receiving waterbody and ambient air quality. In this study, a field pilot-scale CL with ex situ nitritation/in situ denitritation process was constructed and operated continuously under wide temperature variations. The effect of low temperature on leachate treatment, and LFG content was studied. Results showed that the combined process can efficiently remove nitrogen and organic matters from leachate, and change LFG content under low-temperature condition. In the ex situ nitritaion, maximum removal efficiencies of ammonia and chemical oxygen demand (COD) were over 99% and 85%, respectively. The loading rate of nitrogen and COD reached 0.5kgNm-3 d-1 and 0.7kg COD m-3 d-1, respectively. The inhibitions of free ammonia (FA) and free nitrous acid (FNA), and low temperature were the key factors affecting nitritation. With recirculating nitrified leachate, total oxidized nitrogen (TON) was completely reduced, and the refuse decomposition was accelerated. Denitritation was the main reaction responsible in the CL. Additionally, methane content was observed lowly at non-inhibitory TON loading rate of 5.8±3.7gN ton-1 TS d-1. This decrease was not caused by the increased of TON loading, but a carbon source competition by denitrificans. The estimated COD consumption and methane reduction were 55.0kg d-1 by TON reduction, and 20m3 d-1, respectively. Hence, this study served a potential strategy for postclosure care of landfills under low temperature variation.

Influence of moisture content and leachate recirculation on oxygen consumption and waste stabilization in post aeration phase of landfill operation

Sustainable completion of municipal solid waste landfills requires post-closure care after a time when utilization of landfill gas produced from biodecomposition of organic waste be not possible/or economically feasible. Research proved that in-situ aeration is a promising approach employed for landfill aftercare. The application of post aeration operation is targeted to achieve accelerated waste stabilization to avoid long term environmental and public health impacts from landfills. In in-situ aeration operation, consumption of supplied oxygen has significant influence on biological stabilization of solid waste placed in the landfills. The consumption of oxygen is regulated by operation parameters of landfill – one of the important is presence of moisture in landfill ecosystem. This research aims to assess the influence of moisture content and leachate recirculation on the oxygen consumption during post aeration phase of landfill operation. The effect of oxygen consumption on the extent of waste stabilization achieved after experiment was also assessed. Three lab-scale landfill simulation reactors (LSRs) were used – in two of three reactors (LSR-1 and LSR-3) operation was carried out in two phases: Anaerobic and post-aeration. One reactor (LSR-2) was operated under anaerobic condition throughout the experiment and used as control. To compare the oxygen consumption, conventional landfill (CLF) conditions without excess water addition and leachate recirculation were simulated in LSR-1 and the bioreactor landfill conditions (BRLF) with excess water injection and leachate recirculation were simulated in LSR-3. In CLF 46.4% of supplied oxygen was consumed during post aeration phase while in BRLF only 0.96% of oxygen consumption was noticed. In result of higher oxygen consumption, biostabilization rate of waste in CLF was 7% higher than BRLF at the end of experiment. This study demonstrated that, in presence of low moisture in landfill ecosystem optimal air distribution can be realized which results in enhanced waste oxidization and stabilization.

Antibiotic resistance contamination in four Italian municipal solid waste landfills sites spanning 34 years

Municipal solid waste landfill is now recognized as a significant reservoir of antibiotics and antibiotic resistance genes (ARGs). This study investigates the contamination of antibiotics resistance, in 10 leachate samples collected from four MSW landfills in north Italy spanning 34 years, including ARGs as well as mobile genetic element (MGEs). Antibiotics (0-434740 ng/L) and ARGs (5.56-6.85 × 105copies/μL leachate) were found in leachate. Abundances of the measured ARGs were found to be clustered into two groups with different changing tendencies with landfilling age in different landfills. Even though some antibiotics were banned or limited in Italy, they were found to still occur in landfills and drive the long-term contamination of ARGs indirectly, indicating the persistence of antibiotic resistance. What’s more, the complexity of antibiotic resistance in leachate was found to synthetically relate to antibiotics, metals, microbes and MGEs presenting that Mn, SMX and EFC influence positively (p < 0.01) the contamination of tetW, tetQ, tetM, tetA, ermB, and cat, contributing importantly in new leachate. This study discusses the AR pollution of leachate in Italy where antibiotics are used the most in Europe, less reported in literatures. Our results suggest that a full-scale view for landfill antibiotics resistance should be considered with history of landfills, use of antibiotics and different phase in landfills, with both “relative static” and “dynamic tracking” perspective to focus on the principal antibiotic-resistance pollutants for leachate treatment, and raise the attention for landfill post-closure care and landfill mining.

Case study comparison of functional vs. organic stability approaches for assessing threat potential at closed landfills in the USA

Municipal solid waste (MSW) landfills in the USA are regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA), which includes the requirement to protect human health and the environment (HHE) during the post-closure care (PCC) period. Several approaches have been published for assessment of potential threats to HHE. These approaches can be broadly divided into organic stabilization, which establishes an inert waste mass as the ultimate objective, and functional stability, which considers long-term emissions in the context of minimizing threats to HHE in the absence of active controls. The objective of this research was to conduct a case study evaluation of a closed MSW landfill using long-term data on landfill gas (LFG) production, leachate quality, site geology, and solids decomposition. Evaluations based on both functional and organic stability criteria were compared. The results showed that longer periods of LFG and leachate management would be required using organic stability criteria relative to an approach based on functional stability. These findings highlight the somewhat arbitrary and overly stringent nature of assigning universal stability criteria without due consideration of the landfill’s hydrogeologic setting and potential environmental receptors. This supports previous studies that advocated for transition to a passive or inactive control stage based on a performance-based functional stability framework as a defensible mechanism for optimizing and ending regulatory PCC.

Air quality assessment during indoor use of the tobacco heating system THS2.2

The wastes placed at a sanitary landfill contain biodegradable, nondegradable, and semidegradable matters. The biodegradable matters will be rapidly decomposed chemically and biologically into stabilized substances such as humus and inorganic fractions, which is referred to as aged refuse in this book. For the organic wastes, most organic carbon are converted into gases, few into leachate, and others remained as aged refuse. Higher temperature will lead to more rapid degradation and result to higher conversion of the organic carbon to biogas and lower to both solid residues and leachate. The refuse at landfill might be fully mineralized and the accumulative settlement might be over 30% of the initial height after around 22–30 years closure, and postclosure care may be stopped after 22 years, while chemical oxygen demand concentrations in leachate would be reduced naturally to 300 mg/L after over 15 years. A similarity and disparity comparison for different-scale lysimeters with a refuse weight from several hundred kilograms to 10,800 tons, is made, and find that a similarity exists from viewpoint of refuse degradation mechanism and declination tendency of leachate quality and refuse composition among these varied scale lysimeter. An enough weight of waste, such as over 200 kg, should be used at lab when the landfill stabilization process is simulated. The relationships between the refuse components and composition with refuse age are explored in detail and found that the wastes can be considered to be stabilized and become recyclable aged refuse after 8–10 years of placement in China. The air quality at the aged refuse mining point is acceptable and only total bacteria and PM10 may be over the control values. Microbial communities in aged refuse are much more complex than expected. Most of the predominant bacteria in aged refuse exhibit high identity to some extremophiles found in extreme conditions such as highly alkaline and/or saline environments, rocks of an ancient gold mine, old sediments, hypertolerant to arsenic, cold sulfur-rich spring, and the Qinghai-Tibet Plateau permafrost region. The predominated bacilli-like bacteria coexisted with methanogenic archaea, with a rich source of extremophiles, especially alkaliphilic and/or halophilic microbes.

The S.An.A.® concept: Semi-aerobic, Anaerobic, Aerated bioreactor landfill

Hybrid Bioreactor Landfills are designed to enhance and speed up biological processes, aiming at reducing the duration of post operational phase until landfill completion. S.An.A.® (Semi-aerobic, Anaerobic, Aerated) concept consists in a Hybrid Bioreactor featuring a first semi-aerobic phase to enhance the methane production occurring in the following anaerobic step and a forced aeration for the abatement of the residual emissions. At the end of the last step, semi-aerobic conditions are restored and flushing applied for leaching residual non-biodegradable compounds. Results of the application of S.An.A.® concept to a lab scale bioreactor system showed that pre-aeration was effective in controlling the concentration of VFA, increasing pH and stimulating methane production during anaerobic phase; in particular with intermittent airflow the methane potential was 50% higher respect to control reactors. Forced aeration reduced organic compounds and nitrogen concentration in leachate of an order of magnitude, better performing in low airflow reactors. S.An.A.® Hybrid bioreactors proved to be an efficient system both for increasing methane production and reaching landfill completion in shorter time, suggesting that with proper landfill management, the duration of post-closure care might be reduced by 25–35%.

Green and sustainable remediation practices in Federal Agency cleanup programs

Federal agencies manage hazardous waste sites under the assumption that environmental restoration will improve the environment by returning contaminated groundwater to beneficial use, removing waste residuals from a site, treating discharges to surface water, and reducing overall risks to human health and the environment. However, the associated time-consuming and expensive operations, extensive performance monitoring, and post-closure care can lead to unanticipated environmental impacts due to both the technological nature of these cleanup activities and the related protracted timelines. These life-cycle impacts can and should be included in the evaluation of remedial alternatives. Increasingly, Federal agencies are considering these life-cycle impacts—variously referred to as “environmental footprint analysis,” “sustainable remediation,” “green remediation,” “greener remediation,” and “green and sustainable remediation”—when evaluating environmental restoration approaches. For the purposes of this paper, this concept will be referred to as “green and sustainable remediation” (GSR), with application of GSR assumed to take place across the cleanup life cycle, from the investigation phase through site closeout. This paper will discuss the history of GSR, what GSR is, who is implementing GSR, and GSR metrics. The paper will also discuss two approaches to GSR, using case studies to understand and implement it; the first will be a qualitative approach, and the second a more detailed quantitative approach.

Waste Informatics: Establishing Characteristics of Contemporary U.S. Landfill Quantities and Practices.

Waste generation is expected to increase in most countries for many decades with landfill disposal still the dominant solid waste management method1-3. Yet, operational characteristics of landfills are often poorly understood with comparative statistics substantially lacking. Here, we call for a more formal waste informatics to organize and standardize waste management knowledge at multiple spatial scales through analysis of recently reported data from 1232 U.S. landfills and other high resolution data sets. We create the first known estimate of available U.S. municipal waste stocks (8.5 billion tonnes) and go on to resolve these stocks at the county level, reflecting prospective urban mining opportunities. Our analysis of disposal rates and landfill capacities reveals that more than half of U.S. states have more than 25 years of life remaining. We also estimate the gross energy potential of landfill gas in the U.S. (338 billion MJ/yr) by examining 922 operational methane collection systems and demonstrate that the greatest energy recovery opportunities lie at landfills with existing collection systems and energy conversion infrastructure. Finally, we found that the number of landfills reaching the federally defined 30-year postclosure care period will more than triple in the coming two decades, with 264 sites expected by the year 2044, highlighting the need to develop and standardize metrics carefully to define and standardize when it is appropriate to end or scale back long-term landfill monitoring.

Performance and completion assessment of an in-situ aerated municipal solid waste landfill – Final scientific documentation of an Austrian case study

By converting anaerobic landfills into a biologically stabilized state through accelerating aerobic organic matter degradation, the effort and duration necessary for post-closure procedures can be shortened. In Austria, the first full-scale application of in-situ landfill aeration by means of low pressure air injection with simultaneous off-gas collection and treatment was implemented on an old MSW-landfill and operated between 2007 and 2013. Besides complementary laboratory investigations, which included waste sampling from the landfill site prior to aeration start, a comprehensive field monitoring program was conducted to assess the influence of the aeration measure on the emission behavior of the landfilled waste during the aeration period as well as after aeration completion. Although the initial waste material was described as rather stable, the lab-scale aeration tests indicated a significant improvement of the leachate quality and even the biological solid waste stability. However, the aeration success was less pronounced for the application at the landfill site, mainly due to technical limitations in the full-scale operation. In this paper main performance data of the field investigation are compared to four other scientifically documented case studies along with stability indicators for solid waste and leachate characteristics in order to evaluate the success of aeration as well as the progress of a landfill towards completion and end of post-closure care. A number of quantitative benchmarks and relevant context information for the performance assessment of the five hitherto conducted international aeration projects are proposed aiming to support the systematization and harmonization of available results from diverse field studies and full-scale applications in future.

Aeration of the teuftal landfill: Field scale concept and lab scale simulation

Long lasting post-closure care (PCC) is often the major financial burden for operators of municipal solid waste (MSW) landfills. Beside costs for the installation and maintenance of technical equipment and barriers, in particular long term treatment of leachate and landfill gas has to be paid from capital surplus. Estimations based on laboratory experiments project time periods of many decades until leachate quality allows for direct discharge (i.e. no need for further purification). Projections based on leachate samples derived from the last 37years for 35 German landfills confirm these assumption. Moreover, the data illustrate that in particular ammonium nitrogen concentrations are likely to fall below limit values only after a period of 300years.In order to avoid long lasting PCC the operator of Teuftal landfill, located in the Swiss canton Bern, decided to biologically stabilize the landfill by means of a combined in situ aeration and moisturization approach. In December 2014 the aeration started at a landfill section containing approximately 30% of the total landfill volume. From summer 2016 onwards the remaining part of the landfill will be aerated. Landfill aeration through horizontal gas and leachate drains is carried out for the first time in field scale in Europe. The technical concept is described in the paper.Parallel to field scale aeration, investigations for the carbon and nitrogen turnover are carried out by means of both simulated aerated landfills and simulated anaerobic landfills. The results presented in this paper demonstrate that aeration is capable to enhance, both carbon mobilization and discharge via the gas phase. This effect comes along with a significant increase in bio-stabilization of the waste organic fraction, which positively affects the landfill emission behavior in the long run. In terms of leachate pollution reduction it could be demonstrated that the organic load decrease fast and widely independent of the adjusted aeration rates whereby ammonium nitrogen load efficiently decrease later and only under higher aeration rates.

Potential SRF generation from a closed landfill in northern Italy

The aim of this work is to assess the possibility of producing solid recovered fuel (SRF) and “combustible SRF” from a landfill located in the north of Italy, where the waste is placed in cylindrical wrapped bales. Since the use of landfills for the disposal of municipal solid waste has many technical limitations and is subject to strict regulations and given that landfill post-closure care is very expensive, an interesting solution is to recover the bales that are stored in the landfill. The contents of the bales can then be used for energy recovery after specific treatments.Currently the landfill is closed and the local municipal council together with an environmental agency are considering constructing a mechanical biological treatment (MBT) plant for SRF production.The municipal solid waste that is stored in the landfill, the bio-dried material produced by the hypothetically treated waste in a plant for bio-drying, and the SRF obtained after the post-extraction of inert materials, metals and glass from the bio-dried material were characterized according to the quality and classification criteria of regulations in Italy.The analysis highlighted the need to treat the excavated waste in a bio-drying plant and later to remove the inert waste, metals and glass. Thus in compliance with Italian law, the material has a high enough LHV to be considered as “combustible SRF”, (i.e. an SRF with enhanced characteristics).

Post-closure care of engineered municipal solid waste landfills.

Post-closure care is divided into perpetual care (PPC) and long-term care (LTC). Guidelines for post-closure care and associated costs are important for engineered municipal solid waste (MSW) landfills. In many states in the USA, landfill owners are required to set aside funds for 30-40 years of LTC. Currently there are no guidelines for PPC, which is also required. We undertook a pilot study, using two landfills (note: average landfill capacity 2.5 million MT MSW waste) in Wisconsin, to establish an approach for estimating the LTC period using field data and PPC funding need. Statistical analysis of time versus concentration data of selected leachate parameters showed that the concentration of most parameters is expected to be at or below the preventive action limit of groundwater and leachate volume will be very low, within 40 years of the LTC period. The gas extraction system may need to be continued for more than 100 years. Due to lack of data no conclusion could be made regarding adequacy of the LTC period for the groundwater monitoring system. The final cover must be maintained for perpetuity. The pilot study shows that although technology is available, the financial liability of maintaining a 'Dry Tomb' design for landfills is significantly higher than commonly perceived. The paper will help landfill professionals to estimate realistic post-closure funding and to develop field-based policies for LTC and PPC of engineered MSW landfills.

Evaluation of monitoring indicators for the post-closure care of a landfill for MSW characterized with low lignin content

To understand the applicability of the termination indicators for landfill municipal solid waste (MSW) with low initial lignin content, four different accelerated landfill stabilization techniques were applied to anaerobic landfilled waste, including anaerobic flushing with water, anaerobic flushing with Fenton-treated leachate, and aerobic flushing with Fenton-treated and UV/H2O2-treated leachate. Termination indicators, including total organic carbon (TOC), ammonia-N (NH4+-N), the ratio of UV absorbance at 254nm to TOC concentration (SUVA254), fluorescence spectra of leachate, methane production, oxygen consumption, lignocellulose content, and humus-like content were evaluated. Results suggest that oxygen consumption related indicators used as a termination indicator for low-lignin-content MSW were more sensitive than methane consumption related indicators. Aeration increased humic acid (HA) and (HA+FA)/HyI content by 2.9 and 1.7 times compared to the anaerobically stabilized low-lignin-content MSW. On the other hand, both the fulvic acid (FA) and hydrophilic (HyI) fractions remained constant regardless of stabilization technique. The target value developed for low-lignin-content MSW was quite different than developed countries mainly due to low residual biodegradable organic carbon content in stabilized low-lignin-content MSW.

A cost-benefit analysis of landfill mining and material recycling in China

Landfill mining is an environmentally-friendly technology that combines the concepts of material recycling and sustainable waste management, and it has received a great deal of worldwide attention because of its significant environmental and economic potential in material recycling, energy recovery, land reclamation and pollution prevention. This work applied a cost-benefit analysis model for assessing the economic feasibility, which is important for promoting landfill mining. The model includes eight indicators of costs and nine indicators of benefits. Four landfill mining scenarios were designed and analyzed based on field data. The economic feasibility of landfill mining was then evaluated by the indicator of net present value (NPV). According to our case study of a typical old landfill mining project in China (Yingchun landfill), rental of excavation and hauling equipment, waste processing and material transportation were the top three costs of landfill mining, accounting for 88.2% of the total cost, and the average cost per unit of stored waste was 12.7USDton−1. The top three benefits of landfill mining were electricity generation by incineration, land reclamation and recycling soil-like materials. The NPV analysis of the four different scenarios indicated that the Yingchun landfill mining project could obtain a net positive benefit varying from 1.92 million USD to 16.63 million USD. However, the NPV was sensitive to the mode of land reuse, the availability of energy recovery facilities and the possibility of obtaining financial support by avoiding post-closure care.

The Emerging Issue of Solid Waste Disposal Sites Emissions in Developing Countries: The Case of Brazil

While the main concerns with municipal solid waste in developed countries like the European Union and the United States are to reduce and recycle the energy recover in order to drastically reduce the residues disposal to landfill, for developing countries the targets on waste management are much more basic. This seems to be the case in Brazil that with a new regulation, it still attempts to eradicate the inadequate waste disposal for open dumps. Thus, the aim of this paper is to depict the context, the criteria and discuss the strategies used for: the municipalities achieve the goals and adhere the plan; choice and configuration of disposal sites; and economic instruments adopted and bringing the whole scenario to discussion, including methane emissions inventory thru the case study of the Rio de Janeiro State. The Rio de Janeiro State municipal solid waste management scenario has drastically changed in last five years from 9% of residues sent to adequate destinations, to the perspective of eradication of open dumps before the end of 2014. The results indicate that only adequate disposal of waste is mandatory with the prevalence of the sanitation approach. The evidences also indicate that planning goals to reduce waste are modest and the landfill gas recover is generally accepted as the optimal solution. This paper concludes that, unless the stakeholders add to the plan a more aggressive policy to increment, the competitiveness of other waste technologies that favor the landfilling reduction and energy recover, Rio de Janeiro State will face the increase of landfill numbers and sizes, management cost, environmental and leachate impact, post-closure care expenses, contaminating life-span, and methane emissions.

Landfill aeration within the scope of post-closure care and its completion

The time frame required for post-closure care of Municipal Solid Waste (MSW) landfills is often assessed over several decades or centuries. One possibility to significantly shorten this period and, at the same time, improve the emission behavior exists with in situ aeration. Positive effects in connection with this method for biological stabilization have been investigated and published elsewhere. However, until today neither generally accepted monitoring guidelines nor completion criteria have been defined. With the paper on hand the authors propose a methodology for the assessment of both, total and remaining stabilization periods for aerated landfills. The central component of this methodology is a carbon balance. The latter is based on a detailed waste characterization in combination with online monitoring of the emissions (gas and leachate). The methodology is exemplarily demonstrated by means of data derived from a full scale project in Northern Germany. Here it could be shown that the predicted aeration period of approximately 6.4years was sufficient to bio-stabilize the landfill.Furthermore, proposals for the completion of landfill aeration are presented. In this connection, carbon balance is of particular importance since the amount of biodegradable organic carbon mainly determines the emission potential. Additional parameters, aiming at a validation of the state of biological stabilization achieved during aeration are proposed and described.

Improved methodology to assess modification and completion of landfill gas management in the aftercare period

Municipal solid waste landfills represent the dominant option for waste disposal in many parts of the world. While some countries have greatly reduced their reliance on landfills, there remain thousands of landfills that require aftercare. The development of cost-effective strategies for landfill aftercare is in society’s interest to protect human health and the environment and to prevent the emergence of landfills with exhausted aftercare funding. The Evaluation of Post-Closure Care (EPCC) methodology is a performance-based approach in which landfill performance is assessed in four modules including leachate, gas, groundwater, and final cover. In the methodology, the objective is to evaluate landfill performance to determine when aftercare monitoring and maintenance can be reduced or possibly eliminated. This study presents an improved gas module for the methodology. While the original version of the module focused narrowly on regulatory requirements for control of methane migration, the improved gas module also considers best available control technology for landfill gas in terms of greenhouse gas emissions, air quality, and emissions of odoriferous compounds. The improved module emphasizes the reduction or elimination of fugitive methane by considering the methane oxidation capacity of the cover system. The module also allows for the installation of biologically active covers or other features designed to enhance methane oxidation. A methane emissions model, CALMIM, was used to assist with an assessment of the methane oxidation capacity of landfill covers.

A review of approaches for the long-term management of municipal solid waste landfills

After closure, municipal solid waste (MSW) landfills must be managed and controlled to avoid adverse effects on human health and the environment (HHE). Aftercare (or post-closure care) can be brought to an end when the authorities consider the landfill to no longer pose a threat to HHE. Different approaches have been suggested for long-term landfill management and evaluation of aftercare completion. In this paper, research on aftercare and its completion is analyzed and regulatory approaches for the completion of landfill aftercare are reviewed. Approaches to aftercare could be categorized as (i) target values, (ii) impact/risk assessment, and (iii) performance based. Comparison of these approaches illustrates that each has limitations and strengths. While target values are typically used as screening indicators to be complemented with site-specific assessments, impact/risk assessment approaches address the core issue about aftercare completion, but face large uncertainties and require a high level of expertise. A performance-based approach allows for the combination of target values and impact/risk assessments in a consistent evaluation framework with the aim of sequentially reducing aftercare intensity and, ultimately, leading to the completion of aftercare. At a regulatory level, simple qualitative criteria are typically used as the primary basis for defining completion of aftercare, most likely due to the complexity of developing rigorous evaluation methodologies. This paper argues that development of transparent and consistent regulatory procedures represents the basis for defining the desired state of a landfill at the end of aftercare and for reducing uncertainty about the intensity and duration of aftercare. In this context, recently presented technical guidelines and the ongoing debate with respect to their regulatory acceptance are a valuable step towards developing strategies for the cost-effective protection of HHE at closed MSW landfills. To assess the practicality of evaluation methodologies for aftercare, well-documented case studies including regulatory review and acceptance are needed.

Improvement of data quality for post-closure care of landfills using a tiered decision matrix approach case studies

The development of a systematic approach which can be used as a decision-making tool to extend or shorten the post-closure care (PCC) period requires technically sound and justifiable methods. These methods can incorporate analysis and interpretation of available data and information from closed landfill. Analysis of existing data from closed landfills may present challenges due to variations in the data collection procedures, data analysis methods and reporting methodologies used during active and post-closure periods of a landfill. A tiered decision matrix was developed to assess and verify the quality of monitoring data collected and documented from closed landfills. The matrix provides a baseline for the needs to improve the quality of data collection and documentation for current and future practices. Challenges due to discrepancies in data reporting and inconsistencies in quality assurance/quality control protocols during data collection, reporting, and analyses are presented with case studies. Solutions are presented to validate and improve the quality of available data based on this study.