Geoenvironmental Practices and Sustainability

Geophysical methods used to image landfill interiors in Northern Illinois have evolved from the relatively simple one-dimensional (1D) resistivity soundings, used in the 1970s and 1980s, to more sophisticated two-dimensional (2D) resistivity and seismic refraction tomography profiles, augmented by ground-penetrating radar (GPR) and geophysical well logging. To illustrate this evolution of methods, geophysical imaging is described at two sites: the Mallard North landfill in Hanover Park, IL, and the Orchard Hills landfill, near Davis Junction, IL.Resistivity soundings from Mallard North were inverted for true resistivity. The resistivity of municipal solid waste (MSW), mixed with clay soil, was between 9 and 19 Ω-m (unsaturated) and between 2 and 7 Ω-m (leachate saturated). Refuse thickness and leachate levels were also accurately predicted.Orchard Hills 2D resistivity surveys showed most MSW had resistivities between 20 and 130 Ω-m (unsaturated). MSW resistivity near the leachate recirculation lines fell by as much as 3% after leachate injection started. Elastic properties of the waste were assessed using seismic wave velocities from seismic refraction tomography. The final tomographic model consisted of hundreds of cells ranging in P-wave velocity from 350 to 643 m/s, with an average value of 484 m/s. Two separate regions were identified: an upper zone consisting of a lower velocity (380–460 m/s), 3–6 m thick, and a deeper region of higher velocity (505–560 m/s). Poisson’s ratio ranged from 0.38 to 0.44 with the deeper waste exhibiting higher Poisson’s ratios, suggesting less rigidity.

The degradation process of a municipal solid waste (MSW) sample from a landfill in Texas (TX), USA, was monitored in a large-scale laboratory landfill simulator for 1136 days. Simple shear testing was performed on reconstituted fresh and degraded waste specimens and an “undisturbed” degraded specimen. Shear resistance at 10% shear strain was defined as the shear strength in this study. The shear strength of the degraded waste was found to be 17–35% lower than the shear strength of the fresh waste. The effective friction angles of the fresh and degraded waste were 17–21° and 12–17°, respectively. The relatively low friction angles are due to the low compaction effort and density of the specimens. The shear strength of a specimen removed from the simulator in an “undisturbed” manner was found to be nearly identical to the shear strength of a reconstituted degraded specimen.

Landslide is one of the major geological disasters that pose serious threat to the communities. The use of electrochemical stabilization techniques can provide effective remediation for shallow and intermediate depth landslide failures through cohesive weak soils. It is a promising alternative to conventional remediation measures under situations where regular construction loads might trigger catastrophic landslide failure. Electrokinetic treatment, however, requires a large amount of electricity that is typically produced with a mobile fuel-based generator. The high fuel consumption and carbon dioxide emission lead to undesirable economic and environmental consequences. Renewable energy such as the wind and solar energy provides a promising electricity supply for electrochemical treatment. This paper provides a conceptual analysis on the electrochemical treatment with renewable wind energy. The results show that electrokinetic soil improvements using a renewable generator can be more economical than the traditional generator. It is an environmental friendly option for electrokinetic stabilization of landslide.

Pseudo-dynamic limit equilibrium-based analytical solutions to predict the sliding failure of MSW landfill under seismic conditions have been proposed. The proposed methodology incorporates the influences of time period and phase in the analyses. Various MSW landfills with sidehill configurations founded on (a) horizontal and partly sloping base, (b) sloping base and (c) stepped base are analysed. Results are presented in terms of yield acceleration coefficient. Neglecting seismic vertical acceleration brings about 14–28% increase in yield acceleration coefficient for the case of stepped base. The influence of landfill length to height (L/H) ratio is more prominent for the landfill founded on sloping base. Coefficient of yield acceleration is increased by 36%, with increase in L/H ratio from 2 to 10. These results with proposed methodology can be used for seismic design of MSW landfill considering sliding stability.

Understanding of the dynamic properties of municipal solid waste (MSW) and the response of waste landfill for cyclic loads are important for safe seismic design and ensuring sustainability of landfills. This study presents estimation of the dynamic properties through field and laboratory tests of MSW landfill and dynamic response of Mavallipura landfill in Bangalore. Both field tests and laboratory tests are used to develop model to represent variation of shear modulus and damping ratio for different strain levels. Ten ground motions are selected based on regional seismicity of landfill site, and detailed site response analysis was carried out considering one-dimensional nonlinear analysis in DEEPSOIL programme. Surface response parameters have been estimated; the surface spectral response varied from 0.6 to 2 g and persisted only for a period of 1 s for most of the ground motions. The minimum and maximum amplifications are 1.35 and 4.05. This study shows that Indian MSW has less shear stiffness and loose filling, may be subject to more amplification for moderate earthquake ground motions, which need to be accounted for seismic design of landfills.

It is obvious to note that there is a significant amount of variability connected with shear parameters of municipal solid waste (MSW) landfills. To ensure uniform safety and reliability, the design approaches in the US have progressively transformed to the load and resistance factor design (LRFD) format. It may be desirable to the successful development and adoption of reliability-based resistance factors for the design of landfill slopes taking into account the significant variability of shear strength parameters. The exhaustive studies reported on shear parameters of MSW are compiled and reviewed. The mean, standard deviation, and coefficient of variation (COV) associated with shear parameters are obtained using statistical analysis. The probability density functions (PDFs) are plotted for unit weight, cohesion, and friction angle. The PDFs show that high range of variability associated with shear parameters and should be given due consideration in the optimum designs. Therefore, the present work reports a procedure for determining the resistance factors for stability number (in terms of unit weight, cohesion) and friction angle of MSW in accordance with LRFD of MSW landfill slopes that target a specific reliability index. A simple first-order reliability method (FORM) is reported to compute the ranges for the resistance factors. Perhaps, this is the first study to propose resistance factors for the design of MSW slopes. The stability number (in terms of unit weight, cohesion) and friction angle of the MSW are treated as random variables. The Spencer method of slices has been employed to formulate the performance function against the sliding failure of finite slopes. It is illustrated that the uniform safety levels can be obtained by using the proposed resistance factors.

This paper presents a summary of the sizes and site characteristics of 30 operational MSW dumps of cities of India with population in excess of one million. The impact of these dumps (which have no liners and inadequate covers) on the environment is discussed. The study presents seven options for rehabilitation of old dumps and demonstrates the use of hazard rating systems to select the suitable option. Six alternatives for enhancing the capacities of existing MSW dumps are also highlighted.

Neutralization is essential for high alkaline wastes like red mud for its effective utilization. As such, the process of neutralization involves treating the red mud with either chemicals or other waste materials. Among several factors that affect the efficiency of the treatment, surface charge characteristics and particle diameter parameters predominantly influence the performance of the neutralization. The present study focuses on examining the surface charge properties which include flocculation and dispersion and determining the particle size characteristics which include mean particle diameter under variable pH conditions. Surface charge properties are interpreted from zeta potential, ζ, measurements made on suspensions prepared with red mud waste at different pH values. The average particle diameter is obtained from the grain size analysis established on the same suspensions using the zeta potential analyser. Results indicate that the zeta potential increases with pH up to a certain pH value of 4 and then begin to fall with the further increase in pH. The zeta potential turned into negative (up to a maximum value of −48 mV) at pH value of 6.6, which denotes the point of zero charge for the red mud, from the initial positive (from a maximum of +41.8 mV) value. However, the value becomes stabilized when the pH is 10 and above. An average particle diameter of (a) 65–150 nm at pH of 3.96 and above 9.00, indicating a complete dispersed state of the grains, and (b) 1660 nm, 2176 nm and 1080 nm at pH of 1.15, PZC (i.e. pH of 6.6) and pH of 7.48, respectively, indicating likely agglomeration of the grains, was recorded with the change in pH of the suspension. The study finds that the waste possesses surface charge characteristics, which appear to be greatly influenced by the pH.

In the past decade, geotextile tubes have emerged as a new technology for dewatering high-water-content dredged sediments from water bodies, by-products, and wastes. These slurry materials are often contaminated and threaten environmental resources if improperly managed. Geotextile tubes present a means to manage these materials in an environmentally responsible and sustainable manner for industrialized and developing countries alike. Keeping sustainability in mind, biodegradable materials and the viability of natural geotextiles for the dewatering and containment system need to be explored. At Syracuse University, the research team has been assessing the viability of using biodegradable geotextiles, natural flocculants, and cellulosic materials for the geotextile tube application. The results, based on both small-scale and large-scale tests, are very promising. This paper provides an overview summary of our studies.

In situ testing methods to obtain geotechnical engineering characterization at landfill sites present considerable opportunities and some challenges. This paper focuses primarily on the use of cone penetration test (CPT) at municipal solid waste and hazardous waste sites. Lessons learned from case histories where CPT has been used, either alone or in combination with other investigation methods, provide useful information for future work in this area.

The management of municipal solid wastes (MSW) in rapidly developing economies such as India presents unique challenges as well as an opportunity to develop creative and technology-appropriate solutions, which are economically and socially sustainable in the long term. Aged wastes are defined in this paper as those municipal solid wastes which have been disposed of in dumpsites and landfills more than two decades ago. The recent 2016 fire at the Deonar dumpsite, which is the largest landfill in Mumbai, brought the spotlight on the urgent and emerging need to address the issue of aged wastes in an urban setting. This paper addresses the problem of handling and managing MSW in such settings and presents potential solutions with a focus on appropriate technological solutions. The efficacy and drawbacks of applying conventional solid waste management solutions from developed economies such as in Europe and the USA to the Indian situation are discussed. The management approaches discussed in this research may be of some relevance in the situations where the wastes are to be mined from old landfills in the USA.

Raman spectroscopy has long offered potential for analytical specificity, sensitivity, and versatility in the study of a broad array of environmentally relevant compounds. As with other optical analytical methods, the use of the technique has been hampered by challenges in optimizing the sensor-sample interface, managing turbidity for quantitative analysis, limiting fluorescence interference, preventing biofouling (particularly for long-term monitoring), and achieving low cost. As outlined herein, research over the last several years has systematically addressed each of these factors so that Raman spectroscopy is arguably ready to be revisited as a robust and flexible field measurement technique and may now warrant targeted development effort so that it may become a more routinely employed field analysis method. In addition, the developments outlined herein are believed to be applicable to material analyses in complex, turbid, and/or fluorescence-prone settings in a broad array of fields.

Global warming may change the wind and wave pattern, thus altering the dynamic behavior of offshore wind turbine (OWT). This study examines the impact of climate change on the sustainable design and wind energy production of monopile-supported OWT in soft clay incorporating future wind speed, wave height, and period. Two offshore locations, namely, at east and west coasts in India, are selected. For both the locations, wind speed, wave height, and wave period are obtained from the buoy deployed by the Indian National Centre for Ocean Information Services (INCOIS) from 1998–2006. Statistical downscaling method is used to predict the future wind speed, wave height, and wave period due to climate change for the period of 2006–2040. The observed data is compared with the downscaled data from the National Centers for Environmental Prediction (NCEP) reanalysis data to calibrate the statistical downscaling model. The general circulation model (GCM) predictor variables for various global carbon dioxide emission scenarios are used for future climate change. This study shows that the modification in design of OWT is required due to change in dynamic behavior of OWT considering future climate.

The integration of geothermal heat exchange techniques in structural pile foundation is gaining acceptance to cater the heating and cooling requirements of a building. The purpose of the present study is to analyze the response of energy pile foundations subjected to heating and cooling cycle through numerical investigations. For this purpose, a highlight of finite element method is used to simulate energy pile group. The interaction between the piles in a group is analyzed during thermal cycle and constant mechanical loading of the piles. The pile response is considered to be linear elastic. The soil behavior is reproduced using a constitutive model CASM, based on concepts of critical-state soil mechanics. The CASM model has been implemented in finite element software Abaqus through user-defined material subroutines. In the present study, the axial stress distribution in the piles in a group of six piles is analyzed. It is observed from the results that the thermal piles are subjected to heating-induced excess load in addition to the axial mechanical load from the superstructure. However, for nonthermal piles, unloading of the piles happens during heating of the thermal piles. Heating of the thermal piles causes an increase in the axial stress in the thermal piles and decrease in axial stress in the nonthermal piles. However, the cooling of the piles causes decrease in axial stress in thermal piles and an increase in axial stress in nonthermal piles. At the end of cooling, there is a setup of additional axial stress in the thermal piles as compared to the nonthermal piles. The analysis results conclude that the thermally induced axial stress should be taken into consideration for the geotechnical design of energy piles.

The importance of non-stationarity in loads and resistances of geo-infrastructure is pointed out in this paper. Temporal variations of loads and resistances are now becoming an inherent aspect of civil infrastructure systems, particularly because of the effect of climate change. Non-stationarity of loads and resistances affects the sustainability and resilience of geo-systems and, if not taken into account properly, may lead to unsustainable outcomes. Inherent in the concept of resilience is the aspect of temporal variation, and therefore time-dependent reliability estimation of a system can be related to its resilience. An example of time-dependent reliability calculation for an offshore wind turbine (OWT) foundation is presented. How such calculations can be related to the resilience and sustainability of OWTs is conceptually outlined.

Past failures of pile foundation-supported structures during earthquake had lead engineering community to develop sustainable design guideline. Dynamic soil-structure interaction (DSSI) is important in seismic design because it leads to increased or decreased response that of conventional fixed base design. Inherent variability of soil parameters and modeling considerably affects the dynamic response of structure which leads to precise estimation of safety factor. This study attempts to propose a reliability-based design solution for piled raft foundation considering interaction among soil-pile and superstructure under seismic loading. In situ variability of undrained shear strength of soil and different DSSI modeling is incorporated. Response statistics of an idealized structural system supported on piled raft foundation embedded in homogenous soft clay is calculated using Monte Carlo simulation (MCS). Probability of failure is assessed and design implications are also suggested. Finally, this study highlights importance of reliability-based design of piled raft foundation and rational choice of DSSI modeling which may help sustainable design of piled raft foundation.

INTERRA provided quality control (QC) or quality assurance (QA) for large infrastructure projects spanning transportation, storm damage risk reduction, and environmental remediation areas. Quality assurance and control have assumed increased significance in creating a green and sustainable economy.

One of the earliest research efforts on internal erosion was funded by the Government of India in 1895 at Thomason Civil Engineering College, Roorkee (Clibborn, 1902). The research was an effort to understand the 1885 failure of the Khanki Weir and use this information to refine design guidance. This led to early improvements in the analysis and design of defensive measures to prevent piping failures of dams, as well as enabling the prediction of the failure of Narora Weir in 1898. Knowledge of potential design flaws has grown significantly through research and, unfortunately, dam failures. The United States has an aging dam infrastructure, with most dams now beyond their anticipated 50-year economic life. Many of the early dams were designed and constructed prior to adequate knowledge of hydrology, liquefaction, backward erosion piping, dispersive soils, and concentrated leak erosion. While modern dam designs utilize defensive measures to address these concerns, many older dams do not. Dam and levee safety practice in the United States is currently undergoing an evolutionary phase in which risk management practices are seeing wider application in order to help prioritize dam rehabilitation work. The US Federal Energy Regulatory Commission, US Bureau of Reclamation, and the US Army Corps of Engineers are currently implementing risk-informed methodologies in their dam safety programs, and the US Army Corps of Engineers is currently extending this methodology to their navigation and levee programs. Some key challenges include needed refinements on the topics of: internal erosion evaluation and prediction, hydraulic loading from extreme events and climate change, site characterization uncertainties, combining and portraying risks for complex systems, and seismic load and post-seismic response predictions. While Col. Clibborn helped dam engineers to begin to understand the mechanics of internal erosion in 1895 and its implications to dam design, much work remains to be completed. Future studies will improve risk assessments resulting in higher confidence and improved risk-informed decisions regarding prioritization of dam rehabilitations.

Economic development over the past century has been powered largely by fossil fuels. Large, centralized coal plants provided the opportunity for increased population density and job growth, resulting in improved manufacturing capacity and prosperity. Our increasing use of oil allowed us to travel farther, transport goods faster, and develop innovative supply chains. However, not every country followed this same development pattern—30% of the world’s rural population still lacks access to electricity per The World Energy Outlook. To put this into perspective, if those in India without electricity constituted the populace of a country, it would be the fourth largest in the world. Without electricity, many people are denied many necessities and luxuries, one of these being access to the wealth of information via the Internet. Providing clean energy that enables economic development and lifts communities to a better living standard while protecting the climate is the seminal challenge for a world of nearly ten billion people. This paper showcases the use of large-scale, energy production from wind and efficiency offered by geothermal exchange by highlighting the use of applied wind energy geotechnics and thermal geotechnics—both of which are elements of the emerging discipline of Energy Geotechnics.

The objective of this paper is to evaluate the performance of coal ash-based barriers subjected to continuous differential settlements in a geotechnical centrifuge. Motor-based differential settlement simulator was used to induce differential settlements with a distortion level up to 0.125 at 40 gravities in a 4.5 m radius large beam centrifuge facility available at the Indian Institute of Technology Bombay, India. A short series of centrifuge model tests were conducted by varying the thickness of coal ash-based barriers. All the developed coal ash-based barriers were subjected to an overburden of 25 kN/m2 equivalent to that of the landfill cap covers. All the models were thoroughly instrumented with linearly variable differential transformers (LVDTs) and Pore pressure transducers (PPTs) to measure vertical settlements and pore water pressure. Digital image cross-correlation (DIC) technique was adopted to arrive at deformation profiles of coal ash-based barriers and strain distribution along the topmost surface of the tested barrier during all settlement stages. The water sealing efficiency was assessed in terms of limiting distortion level and strain at water breakthrough. A 0.6 m-thick coal ash-based barrier with an overburden of 25 kN/m2 was observed to experience a limiting distortion level of 0.068 and a strain at breakthrough of 0.98%. In comparison, a 1.6 m-thick coal ash-based barrier has not registered any water breakthrough and been noted to sustain large deformations. This centrifuge study demonstrates that coal ash-based barriers of an adequate thickness can be used as impervious barriers in landfill cap covers.

Although there are well-established methods for economic (cost) estimation of any process, the estimation of the environmental and the social effects is relatively less understood and rarely incorporated in engineering calculations. In this paper, the effectiveness of different types of vertical barrier system for a present waste dump is compared in terms of the embodied energy (EE) and carbon emission in addition to the targeted service life. The model used for the assessment is streamlined energy and emission assessment model (SEEAM). The project involved constructing the vertical barrier around Bingipura fill in order to prevent the contamination of nearby water body due to the leachate from the waste dump. Different types of barriers are analyzed: sheet pile walls, concrete barriers, and the slurry-based cutoff walls (Na-bentonite). The performance analysis was carried out in the well-established software POLLUTEv7 which indicated the effectiveness of the sodium bentonite (Na-B) slurry wall and Soil-Bentonite backfill over other two for the leachate containment.

The widespread occurrence of organic contaminants demands the use of innovative barrier materials with improved organic sorption efficiency. In the present study, an attempt has been made to assess geotechnical and sorption characteristics of organo clay and its mixture with varying proportions of bentonite. A noticeable increase in plasticity and swelling characteristics and TOC sorption efficiency suggest that organo clay can effectively be used as a sorptive amendment in barrier materials against organic fluids of low polarity without compromising on the permeability.

Preliminary field observations during the removal of a composite geosynthetic liner system that had been exposed for more than a decade are presented. The liner system was installed at a cell in a Subtitle D municipal solid waste landfill in San Luis Obispo, California (USA). The liner system consisted of (from top to bottom) a 1.5 mm-thick black HDPE geomembrane, a needle-punched geosynthetic clay liner (GCL), and a compacted subgrade. The liner system was not covered at any time since construction. The sides of the cell were relatively steep at 2H:1V slopes. Initially, the geomembrane was removed followed by removal of the geosynthetic clay liner. The geosynthetic clay liner panels were observed to be separated at multiple locations with gaps up to 220 mm wide and up to approximately 17 m long. The GCL also was relatively dry with granular consistency. In addition, a significant amount of bentonite that migrated from the GCL had accumulated between the GCL and the geomembrane at the toe of the slope.

The state of the art in geoenvironmental engineering has expanded in breadth to address a range of engineering challenges, including improvement of long-term performance of barriers for waste and chemical containment systems, remediation of contaminated sites, management of contaminated dredged sediments, and development of sustainable (green) infrastructure. Specifically, recent advancements in engineered barrier systems for waste and chemical containment include (1) improved understanding of contaminant transport mechanisms and coupled flows through engineered barriers and (2) development of innovative barriers and barrier materials. Such advancements may allow for enhanced performance of barrier systems as well as motivate future collaborative and interdisciplinary research in these areas, supporting development of more sustainable geoenvironmental practices.

Proper management of waste tires is a major problem in many regions of the world. Scrapped tires in different forms are being used in various civil engineering applications. This paper presents the feasibility study on the use of recycled tire chips mixed with sand as lightweight backfill material for retaining wall applications. Properties of sand and sand-tire chip (STC) mixtures and model tests conducted on retaining wall models with these materials are briefly summarized. Investigations on use of different STC mixtures (different proportions) indicated that STC30 mixture (30% of tire chips by weight) is most efficient in improving wall behavior in terms of displacements and pressures. To evaluate the financial benefits in the construction of cantilever retaining wall for three different sizes (3, 6, and 9 m height) with STC0 (sand alone) and STC30 mixture as the backfill material, wall designs including the structural designs and cost analyses are presented. Based on the feasibility studies, it is indicated that STC30 mixtures have lower bending moment and shear force on stem, heel, and toe. Thus, the STC30 shows the better sustainable backfill material for retaining wall structures providing a financial benefit of about 30%.

Recycling and reuse of waste materials for various civil engineering applications will not only ease problems associated with their disposal but also help preserve dwindling granular materials. In this study, a composite material made up of shredded waste tires and sand is proposed as a fill material in the construction of reinforced retaining walls and reinforced embankments. Accordingly, the pullout resistance of different reinforcements (ribbed metal strip, geogrid, and ladder-type metal) embedded in sand is obtained. In addition, the shear strength characteristics of the mixtures are obtained. Three sizes of tire shreds equal to 9.5 mm in nominal size, and 50–100 mm and 100–200 mm in length are considered. Different mixing ratios of tire shreds in the mixtures are evaluated in the study. For test conditions considered in the study, the pullout resistance factors of metal strips, ladder-type metal, and geogrid reinforcements are proposed. The shear strength of tire shred-sand mixtures in terms of friction angle is found to be in the range 30°–33° in comparison to the end-of-test friction angle for clean Ottawa sand equal to 32°.

Safe disposal of recycled construction materials and industrial by-products has become a real environmental concern. Reclaimed asphalt pavements (RAP) and fly ash are such materials, among many other recycled materials, highly produced and stockpiled across the world. The reuse of these secondary materials in civil engineering applications in large quantities is always a challenge due to their inferior properties. RAP materials in pavement base courses have proven to be a viable alternative not only to conserve the natural resources but also to reduce the environmental pollution and landfilling. Since RAP is inefficient to be used as a pavement material, they are blended with virgin aggregates (VA) or stabilized with cementitious materials.This study characterizes RAP/VA mixes stabilized with alkali-activated fly ash. The presence of the aged bitumen coat over the RAP aggregates may affect the long-term strength and durability of the design mixes; the mixes meet the strength requirements. Hence, the present study verifies the durability of the mixes by subjecting the specimens to aggressive wet–dry cycles to verify the weight loss. The permanency of the stabilizer/activator is also verified through leachate studies. The comprehensive experimental test results indicated that the RAP/VA mixes are durable and found suitable for the base course applications.

Operators of existing waste facilities try to optimize the airspace above already permitted facility boundaries because of the difficulty of permitting greenfield sites for waste disposal. One technique used successfully to maximize the airspace at active disposal sites involves vertical expansion gained by constructing a mechanically stabilized earth (MSE) berm around the perimeter of the landfill footprint. MSE berms utilize reinforcing geosynthetics in combination with soil to create a safe and cost-effective system that increases the usable airspace within a given permitted landfill footprint. This paper presents two case histories where MSE berms were used to increase waste disposal capacity within the permitted facility boundary. The first case study presents an innovative technique used in the construction of a MSE berm over soft dredge material, thereby using the berm for the dual purpose of ground improvement and the provision of additional waste disposal capacity at the landfill site. The second case study details the use of a MSE berm to optimize the footprint of spoil stockpile at a gold mine, thereby eliminating the need for transportation of spoils at the end of operations and reducing capping costs incurred during mine closure.

Cadmium is a very toxic heavy metal which serves no beneficial effect to living organism. Industrial discharge can contain cadmium and contaminate surface water. Phytoremediation, a new cost-effective energy-efficient removal technology, deserves special attention. In the present study, phytoremediation efficiency of Eichornia crassipes from cadmium-contaminated water has been demonstrated. Cadmium removal from solution was dependent upon residual cadmium concentration and treatment period. In this process, macrophytes absorb and accumulate cadmium mainly within its root system. After saturation of cadmium-accumulating sites, harvested plant biomass was dried completely to reduce its volume and then solidified after rendering it as a concrete ingredient for use in concrete industry. This process was intended to restrict mobility of cadmium by compacting it inside some inert material like concrete. Findings of TCLP test ensured this process as eco-safe disposal technique of phtytoremediated plant.

This study is carried out to prepare a sustainable management model for the cleanup of contaminated agricultural land at Jajmau, Kanpur, India, contaminated with heavy metals due to frequent irrigation by partially treated tannery effluents. The proposed model includes three steps: in the first step, the characterization of hot spot (frequently irrigated, low lying, and near the source and village) of area approx. 105 hectares has been carried out by qualitative and quantitative analysis of 336 samples, which were collected from 112 sampling points from the surface and 15 cm and 30 cm depth from the center line of 100 meter square grid to evaluate the characteristics of soil and contaminants. The data evince that the soil in the area is significantly contaminated with heavy metals: Cr (III) 71–773 mg/kg, Cr(VI) 23–32 mg/kg, Pb 27–61 mg/kg, Cu 21–55 mg/kg, Mn 363–901 mg/kg, Fe 25,812–32,201 mg/kg, Zr 280–449 mg/kg, Zn 51–185 mg/kg, and V 113–228 mg/kg. In the second step, potential human health risk has been evaluated based on conservative approach considering potential pathways, the most sensitive receptors, and long-term exposure of the highest contaminant levels on-site. The third step is focused on ranking a set of suitable sustainable remediation techniques for the site using analytical hierarchy process (AHP) method of multicriteria decision analysis (MCDA).

Bioreactor landfills are emerging as a sustainable option in place of traditional landfills because of their inherent benefits such as waste to energy conversion, early waste stabilization, landfill space recovery, and its beneficial reuse with no long-term risks of leachate treatment and disposal. However, the performance of a bioreactor landfill is dictated by the coupled processes within the landfill. Understanding the individual system processes and their interdependencies is crucial in order to numerically model this system. Till date, there is no single model which can account for coupled processes to assess the performance of bioreactor landfills holistically. In this paper, a new mathematical modeling approach is presented that incorporates coupled hydraulic, mechanical, and biological processes in bioreactor landfills. Few results obtained from numerical simulations using this mathematical framework are briefly discussed, and major research challenges associated with the numerical modeling are highlighted.

Uniform distribution of soluble and insoluble materials into saturated porous soil is often challenging for geotechnical applications, due to the random formation of fingers, i.e., a form of instability at the interface of materials with contrasting density and viscosity. A mechanism by which, one could control this random fingering tendency would support a broad array of applications where it is desirable to uniformly penetrate soil with a substance. In our previous research, the use of electromagnetic (EM) waves has been demonstrated to be effective to induce multiphase flow of dense (ρ > 1 g/cm3) materials in aqueous media, as well as to control air-channel formation in air sparging. EM waves with carefully predesigned radiation pattern were shown to induce a directed two-phase flow in aqueous and saturated porous media with relatively low energy input and minimal heat generation. A homogeneous medium of saturated Ottawa sand within a dimensionally scaled cavity (a Plexiglas tank with its walls covered with transparent, electrically conductive films), designed with a reservoir at the bottom plumbed to maintain constant head, was used to simulate the soil medium. Then, a nonaqueous liquid was supplied, an even distribution of which (throughout the soil volume) was desired. In current practice, such an application would have limited success, owing to the aforementioned fingering effects, as well as the relatively slow process of natural dispersion. Such a case is used as the control. In the study case, EM waves were then launched into the cavity using a loop antenna sharing the ground as the cavity at the best impedance-matched frequency. The EM filed was also numerically simulated using COMSOL Multiphysics finite-element analysis software. The model was also experimentally validated using experimental measurement. Observations and measurements of the induced flow are then made to assess the effectiveness of the distribution. Infiltrating materials to be studied include ionic, soluble nonionic, and biological samples, selected based on their value for various geotechnical applications. Subsequent pilot- or field-scale testing is necessary to determine ultimate applicability of the system.