Evaluation Of Landfill Performance Model Research Articles

Water balance estimation for an ordinary solid waste sanitary landfill in Costa Rica

To assess the necessity of treatment systems for leachate generated by ordinary solid waste deposited in a sanitary fill, accurate estimation of the leachate and gas amount produced during biodegradation process is essential. Climatic conditions at the site significantly influence leachate generation; therefore, accurate estimation of rainfall, temperature, solar radiation, and infiltration into the fill is imperative. In this study, we analyzed the water balance of the Miramar landfill in Costa Rica, assessed the amount of leachate produced using various methodologies, and then compared these findings with the field data to identify the best methodology for specific environmental conditions. To comprehensively analyze landfill behavior, as well as the leachate and gases generated from waste decomposition, determining the hydraulic properties of the materials inside the cells is necessary. These properties must consider variables such as the types of materials present at the site, age of the ordinary waste, and their densities. The hydraulic properties of the materials were obtained from various laboratory tests, which included determining the soil–water characteristic curve necessary for assessing unsaturated conditions in the solid waste. These properties are compared with the results of studies conducted in other landfills to validate the current methodology and the obtained results, which can be used for conducting studies on leachate generation or slope stability analysis for sanitary landfill slopes. The amount of leachate generated was estimated using the methodology proposed by Delgado A. (2018). Additionally, the Hydrologic Evaluation of Landfill Performance model (HELP V 4.0) was employed, demonstrating superior estimation compared to recorded field data. The HELP V 4.0 model facilitated the incorporation of different material layers and thicknesses, weather information at the site, slopes, and drainage conditions.

Evaluation of per- and polyfluoroalkyl substances (PFAS) released from two Florida landfills based on mass balance analyses

Per- and polyfluoroalkyl substances (PFAS) have been found at high levels within landfill environments. To assess PFAS distributions, this study aimed to evaluate PFAS mass flux leached from disposed solid waste and within landfill reservoirs by mass balance analyses for two full-scale operational Florida landfills. PFAS mass flux in different aqueous components within landfills were estimated based on PFAS concentrations and water flow rates. For PFAS concentration, 26 PFAS, including 18 perfluoroalkyl acids (PFAAs) and 8 PFAA-precursors, were measured in samples collected from the landfills or estimated based on previous studies. Flow rates of aqueous components (rainfall, evapotranspiration, runoff, stormwater, groundwater, leakage, gas condensate, and leachate) were evaluated through the Hydrologic Evaluation of Landfill Performance model, water balance, and Darcy’s Law. Results showed that the average PFAS mass flux leached from the solid waste standardized by area was estimated as 36.8 g/ha-yr, which was approximately 1 % to 3 % of the total amount of PFAS within the solid waste. The majority of PFAS leached from the solid waste (95 % to 97 %) is captured by the leachate collection system, with other aqueous components representing much smaller fractions (stormwater system at 3 % to 5 %, and gas condensate and groundwater at < 1 %). Also, based on the results, we estimate that PFAS releases will likely occur at least over 40 years. Overall, these results can help prioritize components for waste management and PFAS treatment during the anticipated landfill release periods.

Analytical study on heavy metal output fluxes and source apportionment of a non-ferrous smelter in southwest China

Abandoned Pb/Zn smelters are often accompanied by a large amount of smelting slag, which is a serious environmental problem. Previous studies have demonstrated that slag deposits pose an environmental threat even if the smelters are shut down. Herein, a Pb/Zn smelter and its impacted zone in GeJiu, Yunnan, China were selected as the study area. The risk and source apportionment of heavy metals (HMs) in the soil of the impacted zone were systematically studied. Based on the hydrogeological features, the migration path and output fluxes of the HMs released from smelting slag to the impacted zone were investigated. The HM contents (Cd, As, Zn, Pb, and Cu) in the soil substantially exceeded the screening values of the Chinese soil standard (GB15618-2018). Based on the results of the Pb isotopic and statistical analyses for source apportionment, the contaminated sites and agricultural irrigation water had a large impact on the HMs of soil. The hydrological analysis results showed that runoff, as an HM migration path under rainfall, continued to affect the environment. The water balance calculations using the Hydrologic Evaluation of Landfill Performance model showed that the rainfall was distributed on site as follows: evaporation (57.35%), runoff (32.63%), and infiltration (10.02%). Finally, the output fluxes were calculated in combination with the leaching experiment. As, Zn, Cd, Pb, and Cu runoff had the output fluxes of 6.1 × 10−3, 4.2 × 10−3, 4.1, 1.4 × 10−2, and 7.2 × 10−4 mg/kg/y, and infiltration of 1.9 × 10−3, 1.3 × 10−3, 1.3, 4.0 × 10−4, and 2.2 × 10−4 mg/kg/y, respectively. Therefore, this study offers theoretical and scientific recommendations for effective environmental management and engineering remediation.

Geotechnical evaluation of Ankara clay as a compacted clay liner

This study investigates the geotechnical properties, and mineralogical and permeability characteristics of “Ankara clay” to evaluate its suitability as a compacted clay landfill liner material. The geotechnical index properties of the clayey soil samples collected from the western part of Ankara were determined. All the soil samples were tested for permeability by means of falling head compaction permeameter apparatus. The mineralogy of the soil samples were examined by X-ray diffraction and scanning electron microscope analyses. The cation exchange capacities of the soil samples were determined by the methylene blue adsorption test in order to determine the presence of swelling clay minerals in the soil samples. The influences of the geotechnical indices and mineralogy of Ankara clay on the hydraulic conductivity were investigated. Several landfill profiles containing various compacted clayey lining systems were simulated by the Hydrologic Evaluation of Landfill Performance model. All the soil samples tested led to hydraulic conductivities lower than the suggested regulatory limits (1 × 10−9 m/s) and therefore, are suitable to be utilized as compacted clay liners in potential sanitary landfill sites. Recommendations regarding field construction of the compacted clay liner are provided.

Comparative estimation of the potential groundwater recharge in Al Zerba catchment of Aleppo basin, Syria

Since groundwater is an integral component of natural hydrologic systems, an estimation of groundwater recharge is required to understand the changes in the temporal water budget and groundwater flow system. The rate of groundwater recharge varies widely in space and time particularly in arid to semiarid regions, and it is rather difficult to measure recharge directly. The aim of this study was to assess the natural groundwater recharge in Al Zerba catchment and the interaction between the surface and groundwater. The catchment is classified as an arid to semiarid climate with an aridity index of 0.25 to 0.3 and long-term average annual precipitation ranging from 300 to 350 mm. Delineation of the catchment boundary was carried out using spatial interpolation of elevation data extracted from the digital elevation model. The effects of vegetation and abstraction from pumping wells on the groundwater table were investigated. Furthermore, groundwater recharge was estimated based on water budget, water table fluctuation analysis by using rainfall infiltration breakthrough, and soil water balance using hydrologic evaluation of landfill performance model (HELP3). The results show that groundwater pumping leads negative impact to long-term decrease in groundwater levels, particularly in the dry season, while no significant effects of vegetation on groundwater were observed. Moreover, the result showed an average annual groundwater recharge ranging from 20 to 35 mm/a (about 10 to 15 % of the precipitation period 2001–2010), concentrated in the north and southwestern regions (outcrops of permeable/coarse-grained limestone and a major fault zone).

A new screening model for leachate production assessment at landfill sites

This paper presents an alternative water balance model for predicting leachate production in landfills, from the operative to the post-closure management. The developed model, based on analytical and empirical equations, provides a quantitative estimation of leachate volumes, using a water balance approach which accounts for the different rates of the incoming water, water losses and water consumption. Aging and compression are also included, allowing to assess the progressive variation of hydraulic and physical properties of deposited wastes. In this work, after a brief description of the model architecture, different applications to hypothetical scenarios and to a real landfill are presented. Namely, in order to highlight how aging and biodegradation can influence the expected leachate production, the results of the developed model are also compared with those provided by the Hydrologic Evaluation of Landfill Performance model which neglects both these processes. The obtained results showed that wastes compression may affect leachate prediction in a large extent during operative stage of a landfill, and neglecting these processes could lead to underestimation up to one order of magnitude. Also biodegradation of waste organic matter may result relevant for leachate volumes assessment, influencing water storage capacity of wastes and leading to a leachate production 2–3 times greater than those obtained neglecting these phenomena. Finally, the application of the developed model to the real landfill shows a quite good agreement with the field data, whereas the Hydrologic Evaluation of Landfill Performance model tends to underestimate the leachate volumes with errors up to 80 %.

Quantification of leachate discharged to groundwater using the water balance method and the Hydrologic Evaluation of Landfill Performance (HELP) model

Landfills are a source of groundwater pollution in Gaza Strip. This study focused on Deir Al Balah landfill, which is a unique sanitary landfill site in Gaza Strip (i.e., it has a lining system and a leachate recirculation system). The objective of this article is to assess the generated leachate quantity and percolation to the groundwater aquifer at a specific site, using the approaches of (i) the hydrologic evaluation of landfill performance model (HELP) and (ii) the water balance method (WBM). The results show that when using the HELP model, the average volume of leachate discharged from Deir Al Balah landfill during the period 1997 to 2007 was around, 6800 m3/year. Meanwhile, the average volume of leachate percolated through the clay layer was 550 m3/year, which represents around 8% of the generated leachate. Meanwhile, the WBM indicated that the average volume of leachate discharged from Deir Al Balah landfill during the same period was around 7660 m3/year--about half of which comes from the moisture content of the waste, while the remainder comes from the infiltration of precipitation and re-circulated leachate. Therefore, the estimated quantity of leachate to groundwater by these two methods was very close. However, compared with the measured leachate quantity, these results were overestimated and indicated a dangerous threat to the groundwater aquifer, as there was no separation between municipal, hazardous and industrial wastes, in the area.

Field Hydrology of Landfill Final Covers with Composite Barrier Layers

AstudywasconductedatsevensitesacrosstheUnitedStatestoevaluatethe fieldhydrologyof finalcoverswithacompositebarrier (a geomembrane over a soil barrier or a geosynthetic clay liner) for final closure of landfills. The water balance of each cover was monitored withalarge(10320m)instrumenteddrainagelysimeter.Withoneexception,thecoverslimitedtheaverageannualpercolationto,2.8mm/year (,0.4%ofprecipitation).Thegeomembranebarrieratonesite(Marina,California)waslikelydamagedduringconstruction;percolationatthis site averaged 30 mm/year (6.9% of precipitation). The annual percolation through the cover at the wettest site (Cedar Rapids, Iowa) ranged between0.1and6.2mm/year.Theannualpercolationataridandsemiaridsiteswastypicallynomorethanatrace(,0.1mm/year).Percolation fromalltestcoversgenerallywascoincidentwithhighwaterstorageinthesurfacesoillayerandlateral flowinthedrainagelayeronthesurface of the geomembrane barrier. Water balance predictions were made with the hydrologic evaluation of landfill performance model using site- specific input. Surface runoff was overpredicted and evapotranspiration underpredicted when as-built soil hydraulic properties were used as input. Better agreement was obtained when in-service soil hydraulic properties were used as input. The lateral flow was consistently overpredicted regardless of the hydraulic properties, and no correspondence existed between the predicted and measured percolations. DOI: 10.1061/(ASCE)GT.1943-5606.0000741. © 2013 American Society of Civil Engineers.

Evaluation of an Alternative Method of Leachate Collection System Design

The current practice of leachate collection and removal system LCRS design for sanitary landfills has limitations because of the uncertainties associated with a key design parameter, leachate production rate. The traditional techniques for determining leachate generation are accurate only to within one order of magnitude. One of the drawbacks is the inability of these techniques to account for short-term fluctuations in leachate generation rate caused by heavy rainfall events or leachate recirculation events. This paper presents a rational method to account for fluctuations in leachate generation by incorporating a correction factor to leachate generation rates determined from traditional techniques. The correction factor known as the peak leachate factor PLF is developed from landfill lysimeter and pilot scale test cell studies. It is defined as the ratio between peak and average daily leachate generation rate, and is proposed to be used in conjunction with the output from a leachate generation model such as the hydrologic evaluation of landfill performance model to generate a design leachate generation rate. The potential of applying PLF in the design of a LCRS in full scale landfills is evaluated by studying the scale up possibility of the hydrological behavior of laboratory lysimeters to a field scale landfill test cell. The results demonstrated that the hydrologic behavior of the field test cell is similar to that of the lysimeters. The results indicated that various categories of landfill cells will require the adoption of PLFs depending on the type of waste landfilled and climatic conditions and operational characteristics of the landfills. PLF could be an important design parameter for LCRS in landfills cells, especially those operated with continuous leachate recirculation or located in tropical climates subjected to frequent high intensity rainfall events.

Effect of Leachate Recirculation on Enhancement of Biological Degradation of Solid Waste: Case Study

This paper presents a case study of leachate recirculation at the Trail Road landfill site, located in Nepean, Ontario, Canada. The leachate collected from the landfill leachate collection system is pumped into infiltration lagoons that were built on the working face of the landfilled waste. The locations of these infiltration lagoons are constantly changing to accommodate the landfilling of the municipal solid waste in Stage 3, which has a composite liner consisting of 600 mm of compacted clay and an 80 mil high-density polyethylene geomembrane. The initial estimation of the leachate generation rates in 1991, using the Hydrological Evaluation of Landfill Performance model indicated that leachate recirculation into the landfill could be feasible for a period of 5 to 6 years, after which time a substantial amount of leachate would have to be removed from the system. The average pH of the leachate in the early stage of recirculation was on the acidic side of the pH scale; however, the pH value was in the ra...

Contaminant Leaching Model for Dredged Material Disposal Facilities

This paper describes the hydrologic evaluation of leachate production and quality model, a screening-level tool to simulate contaminant leaching from a confined disposal facility (CDF) for dredged material. The model combines hydraulics, hydrology, and equilibrium partitioning, using site-specific design specifications, weather data, and equilibrium partitioning coefficients from the literature or from sequential batch or column leach tests of dredged material. The hydraulics and hydrology are modeled using Version 3 of the hydrologic evaluation of landfill performance model. The equilibrium partitioning model includes provisions for estuarine sediments that have variable distribution coefficients resulting from saltwater washout. Model output includes contaminant concentrations in the CDF profile, contaminant concentration and mass releases through the bottom of the CDF, and contaminant concentrations and masses captured by leachate collection systems. The purpose of the model is to provide sound information for evaluating the potential leachate impacts on ground water at dredged material CDFs and the effectiveness of leachate control measures.