Geo-Chicago 2016: Sustainable Waste Management and Remediation

Heavy metals presence in soil and groundwater is of utmost importance in terms of risk assessment as their toxicity affects natural systems. The ability of predicting the fate and transport of heavy metals in the environment relies on the efficient modeling of sorption. A major challenge of geochemical modeling is to predict sorption as a function of varying environmental conditions, which can be achieved using surface complexation models (SCM). Unlike empirical distribution factors, SCMs provide a more robust description of sorption reactions on mineral surfaces and can predict sorption as a function of pH, concentration and competing ions. Hexavalent chromium (Cr(VI)) or chromate is a common contaminant and its mobility and reactivity is affected by sorption on iron oxides. To elucidate the chromate sorption on ferrihydrite under various environmental conditions, it is important to construct a predictive model that can describe the adsorption behavior of chromate quantitatively taking into account the sorption mechanisms. This study presents a new 1-pK triple layer SCM based on the surface structure model put forth by Hiemstra (2013) and utilizing multiple surface species (monodentate and bidentate) for chromate sorption. Literature and experimental (batch isotherms and pH edge) data are employed for the calibration and validation of the SCM. Two fittings were performed, one using the literature and one using the experimental data. The model provided a very good fit for literature data with an initial concentration of 5 μM Cr(VI), especially at the low ferrihydrite suspension concentration, while it slightly underestimated adsorption at high ferrihydrite concentration and only in the pH range 7.5-8.5. Modeling of a pH edge obtained with 1 mM Cr(VI) initial concentration led to similar log Ks, however the fit was poorer above pH 6.5. The sensitivity analysis for the choice of surface species showed that this was due to the inclusion of the monodentate species, while the model with only bidentate contribution produced a much improved fit of the pH edge. Similarly, the isotherm at pH 4 is described better by the bidentate model, however the isotherm at pH 5.7 is closer to the monodentate model. Thus, the combined model accounting for both complexes is considered a better choice to capture a wider range of pH and chromate concentrations. Further spectroscopic investigation for chromate adsorption on ferrihydrite is needed to establish a more realistic model to predict adsorption.

Mine tailing and lake sediment from a former mining area in Canakkale (Turkey) were analyzed for physical (e.g. moisture content, particle size, specific gravity, and hydraulic conductivity) and chemical parameters (e.g. organic content, pH, ORP, and EC) as well as heavy metal content and sequential extraction analysis, in an attempt to evaluate their risk as a source of contaminants. Column extraction tests were conducted to investigate the leachability under model field conditions using simulated rainwater. The toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) methods were performed to evaluate the expected concentrations in the water in contact with the solid material. The results showed that both tailing and sediment in the study area were highly acidic (pH=2.2-2.92) and electrical conductivities were high. The column tests proved that Fe and Pb can be released to the waterbodies in contact with the solid materials. Pb was released easier than Fe due to its content in the more labile fractions in the sequential extraction analysis. SPLP-Pb in both tailing and sediment exceeded the U.S. EPA regulatory limit confirming the hazardousness of those materials. All of these results were used to evaluate the most appropriate remedial strategy and to recommend phytocapping as a practical green and sustainable method to mitigate the environmental risk.

Stormwater runoff and non-point source pollution in urban areas remain as a significant water quality issue for many regions of the United States. Urban development increases a variety of environmental pollutants discharge into groundwater in cities with a combined sewer system when the system surcharges the overflow. Among the common stormwater runoff pollutants, heavy metals were considered as priority of attention because they are toxic to aquatic organisms and may persist in the food chain. The heavy metal pollutants are expected to be function of land use which is expected to have a significant influence on their presence. This paper presents an investigation on the water quality of the exfiltrated runoff through permeable pavement (PP) systems and their heavy metal removal efficiency in the metropolitan area of Louisville, Kentucky. A series of field samples from surface and exfiltrated runoff were taken within different rainfall events. The heavy metal pollutant removal efficiency of the PP was investigated by comparing the concentrations in both the runoff and the underdrain. Furthermore, the concentration of heavy metal in the runoff were related with the rainfall characteristics and site condition. Results suggest that an improvement in water quality is achieved by diverting stormwater into PP.

Heavy metals contaminants include lead, chromium, arsenic, zinc, cadmium, copper, and mercury all of which can cause significant damage to human health and the environment as a result of their mobility and solubility within groundwater. In the Midwest portion of the United States, soil and groundwater based lead, zinc, and cadmium are the prominent pollutants of concern. While remedial technologies exist for heavy metals pollution, the majority of these solutions are expensive to design, maintain, and install. Drinking water treatment waste (DWTW) is a currently landfilled, relatively pure, industrial waste byproduct composed almost entirely of calcium oxide produced during water purification processes. Measured doses of drinking water treatment waste were submerged in synthetic groundwater solutions containing 0.01, 0.1, and 1.0 millimolar concentrations of lead, cadmium and zinc in order to determine if this material could provide remedial measures for heavy metals. In addition, the geomechanical properties and chemical composition of the material were determined. Removal rates varied based upon internal and external water content as well as flocculant formation. However, all tests verify that the material is capable of heavy metals removal at relatively rapid rates. This data suggests that when entrained in a previous matrix, the reactive nature of the byproduct sorbs ions in solution passing through the matrix.

More and more attention has been paid to the effects of heavy metal pollution on soil in China. Due to the addition of heavy metal ions, the physical properties of soil will be changed and the microscopic properties, such as soil structure, stress, and soil particle, of soil will also be transformed. In this article, three kinds of heavy metal ions (Zn, Pb and Cd) were used as pollutions to prepare the heavy metal contaminated soil in laboratory. Then the physical and microscopic properties of heavy metal contaminated soils were investigated. Microscopic tests include X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence spectrum (XRFS). The microstructure of heavy metal polluted soils and the fundamental reasons for the observed changes were interpreted based on the above three expriments. Besides, the fines content test and pH test were used to analyze the variation rules of relevant physical properties in heavy metal contaminated soil. At last, the soil characteristics of heavy metal contaminated silt clay were studied by contrastive analysis of the physical and microscopic test. And the characteristics of three kinds of pollutants were compared to each other. The change rule of related properties was analyzed by macroscopic physical properties of three kinds of heavy metal contaminated soil, which could provide the basis for evaluation and treatment of polluted soil.

Leaching of arsenic from ash in coal fly ash disposal facilities is a cause for concern due to possible contamination of groundwater. In this study, leachates of coal fly ash collected from a retired ash basin were characterized, and a high concentration of arsenic (V) was found in the leachates. A manganese coated sand (MCS) was employed to attenuate the arsenic concentration in coal fly ash leachates. A 10 g/L dosage of the sorbent was able to remove about 90% of arsenic content of both ash leachates. The adsorption of arsenic followed the Freundlich adsorption equation, indicative of favorable adsorption of arsenic onto the MCS sorbent. The results from the Dubinin-Radushkevich (D-R) equation were indicative of the physical adsorption of arsenic onto the MCS sorbent. Overall, the sorbent was found to be an effective and sustainable sorbent which may be used in the liner system of coal fly ash disposal and containment facilities to prevent the percolation of arsenic in the leachate down to the groundwater, or it may be used for removal of arsenic after the collection of ash leachate ex-situ.

Chromium, copper and arsenic are leached through soils which are exposed to chromated copper arsenate, a major wood preserving agent. The removal of chromium, copper and arsenic from natural waters down to environmentally acceptable levels is required because of the toxicity of these contaminant species. In this study, the removal of chromium, copper and arsenic from water is investigated using manganese oxide based sorbents. The adsorption of chromium, copper, and arsenic from water using manganese oxide sorbents was evaluated as function of sorbent dosage and time. All manganese oxide sorbents removed appreciable amounts of chromium, copper and arsenic from water within an hour. The manganese coated sand (MCS) may be a sustainable and practical sorbent based on the effective removal of chromium, copper and arsenic from groundwater, and the rapid uptake of the contaminants by the sorbents.

The simultaneously immobilization potential of dissolved Cu, Ni, and Pb in a packed column of freshly crushed steel slag fines (SSF) media was evaluated. The SSF media was characterized as USCS SP type soil with <5% passing the No. 200 (0.075 mm) sieve and the flow rates were on the order of a meter per day with a residence time on the order of 3.5 hours for a 25 cm long column containing approximately 5 kg of SSF media. The combined influent concentrations were in excess of 500 mg/L Cu and Ni, and 5,000 mg/L Pb to be consistent with concentrated waste streams and/or industrial processes. The influent pH of the multi-metal solution was on the order of 4.2; and the pH of the effluent for the test duration of 100 pore volume (PVs) never decreased below 12. Copper and nickel detection (0.05 mg/L) in the effluent was delayed for approximately 46 PV and the copper limit in drinking water (1 mg/L) was reached at 78 PV. The effluent concentrations of Pb exceeded 5 mg/L at approximately 38 PV which corresponded to an immobilization of Pb on the order of 50,000 mg/kg and 5,000 mg/kg each of Cu and Ni.

For waste solids contaminated by hazardous metals, stabilization through thermal treatments can provide an opportunity to reduce the metal release. However, mechanisms of such stabilization strategies were not clearly identified. Many waste-to-resource strategies are employed via using metal contaminated solids in a wide variety of applications, scientific investigations, and quantitative evaluation of the stabilization effects. The understanding of the metal incorporation efficiencies achieved by different metal stabilization mechanisms is also important to assist the design of reliable treatment strategies. This study investigated the incorporation mechanisms between ceramic precursors and hazardous metals (nickel and copper) under different thermal conditions. The results show the important role of forming aluminates and ferrites to significantly reduce metal leachability from products. Quantitative X-ray diffraction (XRD) technique and the prolonged leaching tests were applied to report the metal incorporation efficiencies. The metal leaching behavior on different water-mineral interfaces was also analyzed, together with the examination on the chemical composition of leached surface via the X-ray photoelectron spectroscopy (XPS) technique. With the provided information, this study identified the key mechanisms of stabilizing nickel and copper in the ceramic matrix and also demonstrates the importance of quantitative understanding in the development of safer waste-to-resource strategies.

This study reports on the leaching characteristics of COPR from the soda ash roasting process that contained 8,500 mg/kg of Cr(VI), indicating poor recovery during the leaching process. To this end, leaching with different extraction solutions was studied as a function of time. The DI water, 0.1M NaOH and 1M NaOH leaching results were similar with around 47% of the total available Cr(VI) leaching out up to 480 hours. 1M and 0.1 M Na₂HPO₄ could leach out 58% and 51% of total Cr(VI) at 48 hours, respectively. When compared with 48.7% of Cr(VI) leached by DI water, improvement is not significant. A strongly acidic (pH 0.5) 1M HNO₃ results leached even less than water due to strong sorption and reduction of Cr(VI). However, the acidity of 0.1M HNO₃ is much weaker and the leached Cr(VI) increased significantly up to 90%. Optimum leaching was in the pH range 4-5, while pH above 6 led to decrease in recoverable Cr(VI), indicating that pH control is necessary to facilitate optimum recovery. Collectively, these results indicate that up to 50% of the residual Cr(VI) can be easily recovered with minimum costs, while the remaining is tightly held within the smallest particles, so that it may not be easily recoverable by leaching alone. Treatment of this residual fraction is a more promising avenue.

Lateritic soil treated with up 10% waste wood ash (WWA) and compacted with British standard heavy (BSH) energy (relative compaction = 100%) was evaluated for its absorption and diffusion capacity for selected cations and anions commonly found in landfill leachate. Addition of WWA increased the pH of the medium which immobilized most of the metal ions within the stabilized soil and reduced the availability of ions for desorption thereby making the lateritic soil—WWA mixture more potent to attenuate the concentration of the cations. Generally with increase in WWA content retardation factor reduced while tortuosity increased. For the adsorption and diffusion characteristics, the values of apparent diffusion coefficient, D* decreased with higher WWA content for monovalent cations while it increased for the divalent cation considered; however, it decreased for the anions considered. The tortuosity factor, τ_a also behaved in a similar pattern for all the treated specimens tested. The study showed that lateritic soil treated with 4 % WWA will reduce the detrimental effect of municipal solid waste (MSW) leachate in groundwater via adsorption to the soil matrix and prevent its conductivity through soil by diffusion.

The study of kinetics of metal adsorption in minerals may improve geo-environmental applications of pollutant migration through soils. Pseudo-first-order (PFO), pseudo-second-order (PSO), exponential and Elovich models were applied to describe adsorption of Cd²⁺, Ni²⁺ and Pb²⁺ in the clay-mineral vermiculite, using data from batch tests carried out by Chui (1998). Adsorption was rapid in the first 10 minutes of contact time (more than 50% of the equilibrium adsorption had already occurred) and took place at a much slower rate henceforth. Equilibrium adsorption slightly increased with the increase of pH from 2 to 5, and was significantly lower at pH 1. For the investigated metals, PFO and PSO resulted in poor fits due to the low intensity of the initial rate proposed by these models. In general, Elovich model presented the best fit for Ni²⁺ and Pb²⁺, with coefficients of determination r² higher than 0.9. Cd²⁺ adsorption was not well represented by the tested models.

This paper presents the results of a numerical study pertaining to the significance of consolidation of a compacted clay liner (CCL) on contaminant transport through the CCL serving as the barrier component in a solid waste impoundment bottom liner system. Numerical simulations were conducted using the validated CST2 model, which accounts for one-dimensional coupled large strain consolidation and contaminant transport in saturated porous media. Simulation results indicate that CCL consolidation can play a significant role on contaminant transport through the CCL during the entire 40-year evaluation period. Analyses based on traditional advective-dispersive transport neglect the transient advective transport and changes in CCL properties caused by consolidation process and, therefore, can lead to significantly different results. For the simulations with initial CCL thickness of 0.5, 1, and 1.5 m, consolidation is shown to decrease the steady-state contaminant mass flux by 59%, 67%, and 71%, respectively, and thus ignoring consolidation would produce conservative transport result for single CCL.

This study uses electrical resistivity tomography (ERT), recently introduced as a means of detecting contaminants in the subsurface, to detect oil pollution of sand. A total of 28 stainless steel stakes were placed in a tank filled with Ottawa sand having a moisture content of 2.5%. The stakes were connected to the electrodes of the Advanced Geosciences Inc. (AGI) Supersting R1. Several control surveys were run to obtain the electrical resistivity of the sand before and after application of the contaminant. Engine oil was poured at the surface point to observe changes in the electrical characteristics at the entry spot. Several tests were performed on different days to investigate how the contamination affected resistivity. Locations with oil concentration showed no major changes in electrical resistivity over a period of 7 days. ERT surveys were found useful in detecting oil plumes and their flow in sand.

Proper estimation of contaminant transport rate through compacted fine-grained soils assumes great importance in the context of remediation of contaminated sites. Integrated use of equilibrium and mass transfer rate tests in conjunction with appropriate mass transfer models provide a useful framework for evaluating leaching of contaminants such as lead (Pb²⁺) and zinc (Zn²⁺), which have relatively low pH-dependent solubility. In this article, column experiments were set up to study the diffusion coefficients and break through times using method of slices for two semi-arid soils (Al-Ghat and Al-Qatif) for selected heavy metals (Pb²⁺ and Zn²⁺). The studies were carried out on soil samples before and after amending with lime. Breakthrough curves were obtained under different hydraulic gradients for the compacted mixtures and the diffusion coefficients for Pb²⁺ and Zn²⁺ were evaluated using POLLUTEv7 relying on advection-dispersion equation, for a liner thickness of 1m. The current study allowed us to observe the movement of contaminants in the clay liners to be predicted in real time. Break through curves showed relatively higher retention levels for the targeted metal ions. The retention strength of these soils was observed to be constant up to five pore volumes, corresponding to the pH of the effluent and pore water of soil slices. Soils amended with lime showed an improvement to the order of 10 times in retention capacity. Under pure diffusion controlled migration both soil lime mixtures performed very well and gave breakthrough times of more than 400 years whereas advective-diffusion gave break through times of 200 years for both metal ions considered in the study.

Two methods to measure radon (Rn) flux from earthen Rn barriers were evaluated in this study as part of a larger project to evaluate how pedogenesis (structural development in response to soil formation processes) affects radon flux from earthen surface covers placed over disposal facilities for uranium mill tailings. Calibration methods and flux data are presented for activated carbon (AC) passive collectors and a solid-state alpha particle detector (RAD7). Tests using granite aggregate as Rn source material indicate that the average Rn flux measured using the RAD7 is in good agreement with measurements for similar rock types. Radon concentration measured using AC samplers can be up to 60% less than concentrations measured using the RAD7. The underestimate is likely due to the presence of water vapor in the flux chambers, which reduces availability of Rn sorption sites on AC. Average Rn fluxes were similar for small (area = 0.017 m²), medium (0.071 m²), and large (2.32 m²) flux chambers. However, variability in the flux decreased with increasing sample size due to the effects of spatial averaging, from 43.4% for the small flux chamber to 2.4% for the large flux chamber.

This paper presents the results of permeation of a conventional needle-punched GCL and a dense, factory prepdrated (DPH GCL) with a synthetic multispecies solution with ionic strength I=0.0242 and pH=2.8 containing heavy metals. Both materials were permeated with water to measure a reference hydraulic conductivity k prior to permeation with the synthetic solution. The k of the conventional GCL increased from 2.2×10^-11 m/s (water) to 2.0×10^-10 m/s after 50 pore volumes of permeation (200 days). Conversely, the k of the DPH GCL slightly decreased (6.5×10^-12 m/s) relative to water (k=8.9×10^-11 m/s) after 20 pore volumes (950 days of permeation), likely as a result of precipitation of metal compounds. Solute migration through the GCLs was assessed by determining the breakthrough curves. The solute breakthrough curves of the C CGL were modeled by means of the POLLUTE software.

Beneficial reuse of municipal solid waste incineration (MSWI) fly ash depends on demonstrating that this material presents acceptable environmental risk. Leaching characteristics of trace elements from municipal solid waste incineration (MSWI) fly ash samples were investigated by laboratory leach tests. Concentrations of arsenic (As) and barium (Ba) from water leach tests (WLTs), synthetic precipitation leaching procedure (SPLP), and column leach tests (CLTs) were observed to exceed the maximum contaminant level (MCL) according to U.S. EPA drinking water standards. Concentrations of As from CLTs decreased steadily with increasing cumulative liquid-to-solid ratio (L/S), but still exceeded the MCL at L/S ratio of 10. pH dependent leaching of Ba was observed from batch and column leach tests. Leaching of Ba in one ash sample was 2–3 times higher than another sample in both WLTs and SPLP, with a higher leachate pH of 11.3. Lower concentrations of Ba (30 to 300 μg/L) were observed in CLTs with lower leachate pH. Concentrations of As decreased significantly below pH=4, then showed a steady release with concentrations of 2-10 μg/L for 4<pH<12. Leaching concentrations of boron (B) and Ba were independent of pH until pH=9. Leaching behavior of copper (Cu) followed the cationic pattern in which the concentration of elements steadily decreased with pH.

Nuclear power is an efficient source of power generation with low carbon emissions. But one of the serious problems encountered in the nuclear industry is the development of proper disposal facilities for radioactive waste. The safety of a waste disposal facility depends on the efficiency of its design against contaminant migration. The transport mechanisms of the contaminant are complex processes which involves advection, diffusion and dispersion considering radioactive decay. The heterogeneity of the aquifers and the existence of uncertainty (data and model uncertainty) affect greatly the predictive ability of groundwater flow and contaminant transport models. As a result, in a complex structural system like a near surface disposal facility (NSDF) where low and intermediate level wastes are disposed, the amount of radionuclide released into groundwater post closure is a major concern for the design. It is essential to know the probability of the concentration of radionuclide in the drinking water pathway exceeding the permissible value (probability of failure). Further, the long timescales considered in NSDF are a key feature making treatment of uncertainties more challenging and since the parameters influencing the contaminant process evolve in time, there is a need for a time dependent reliability analysis in this regard. In the present study, the contaminant migration is modelled as a convolution of the repository failure and the transport of the contaminant to groundwater through advection and dispersion. The uncertainties are modelled by considering variability in parameters and the time dependent probability of failure is estimated using Monte Carlo simulations.

Every year a large amount of dredged sediments are disposed or used for land reclamations. To reduce the time lag for construction purposes, electrokinetic stabilization is suggested as an environmentally friendly and cost effective method to dewater and stabilize the dredged mud deposited in the paddocks. However, the physiochemical changes due to the electrochemical reactions in the dredged sediments are drawbacks of this technique that need to be investigated. The type of electrode to be used in the stabilization affects the physiochemical changes, and therefore using the correct type of electrodes is important. Different electrodes are used to stabilize different types of soils. Literature suggests that aluminum is a good option as it improves the soil and causes electrochemical strengthening by inducing Al³⁺ ions into the soil. In this study, the effect of aluminum mesh electrodes on the electrokinetic stabilization of the dredged mud is investigated. After the completion of the electrokinetic stabilization, samples are taken from different depths and water content, pH, electrical conductivity and atterberg limits are determined. From cathode to anode, the liquid limit decreases and plastic limit increases significantly. Near the anode, pH is reduced by 90% and the electrical conductivity increased. Higher salt content is also observed near the anode at the bottom of the column. The lowest water content and highest strength are obtained near the anode. Almost 54 % of the water is removed from the system due to electroosmosis. Despite the electrochemical changes in the soil, its settlement was about 17% which was not very significant; however, variation of electric current shows that the aluminum mesh is corroded before the settlement of the soil is completed. Therefore aluminum mesh electrodes are not suggested to be used for electrokinetic stabilization of dredged mud sediments.

This research aims to compare electrokinetic soil technologies for the removal of pesticides from spiked soils using four different electrodes arrangements: rows of facing electrodes (flushing), a central cathode surrounded by six anodes (1C/6A), a central anode surrounded by six cathodes (1A/6C) and alternate circular distribution of anodes and cathodes (fence). In all cases, long term experiments of soils polluted with 2,4-dichlorophenoxyacetic acid (polar pesticide) and oxyfluorfen (non-polar pesticide) have been carried out in a bench-scale set-up completely automatized and operating on potentiostatic mode. Results show that the four strategies lead to very different results in terms of flushing fluid and pesticide mobilization. Flushing and fence strategies lead to higher water mobilization to cathodic wells, but the volume of water drained by gravity and evaporated are comparable and seem to depend on the water demand, resulting current intensity and temperature. Regarding herbicide transport, both, 2,4-D and oxyfluorfen are dragged towards the cathode wells by electroosmotic fluxes and transported to the anode wells by electromigration, being this last process much more important in the electroremediation of 2,4-D polluted soils. In addition to electrokinetic transport, pesticides are also transferred to atmosphere in non-negligible amounts (at least 25 % of the pesticide).

Decontamination of fine-grained soils from ionic pollutants by conventional methods is not only costly but also mostly ineffective because of their low hydraulic conductivity, low biodiversity and strong adsorption on their surface. To decontaminate soils of low hydraulic conductivity, the application electrical potential along with passing of water under hydraulic gradient has come into vogue. This method is called electro-kinetic remediation. The efficiency of removal of cations near cathode is well established, the removal of anions at anode is not that effective. In this case, the electrical potential causes the migration of anions towards the anode is inhibited by opposing osmotic flow. Hence, the removal of anions by electro-kinetic extraction method is less effective compare to cations, how it will affect the sulphate ion migration has been studied in this paper. From the study, it has been observed that the breakthrough curve of sulphate ion under electrical potential is significantly lower than under advection and diffusion only. It is also concluded that inspite of electro osmotic flow occurring in the opposite direction, the breakthrough of sulphate occurs earlier because of migration of sulphate ion towards anode under electrical gradient.

This work focuses on the evaluation of electrokinetic remediation as a technology for the removal of heavy metals from mine tailings and acid lake sediments sampled in a former mining area in Can Basin (Canakkale, Turkey). The electrokinetic treatment of mine tailing and sediment removed 20% of Pb and Fe in 9 days of treatment at 1 VDC/cm. The removal of metals was very affected by metal speciation which was determined by Tessier method. Electrokinetics could remove metal fractions I–IV in the Tessier method, especially in the closest section to the anode of the solid matrix, and the metals migrated towards the cathode and accumulated in the following sections. The results suggested that Fe and Pb could be effectively removed from the mine tailing and sediment if the advance of the acid front was favored and the treatment time increased.

Electro-osmotic consolidation has long been studied as a soft soil improvement technique. In this study, electro-osmotic consolidation at a certain depth was proposed to improve the drainage and consolidation effect. A series of experiments were performed on kaolinite to evaluate the efficiency, as well as to investigate the influence of effective anode length and intermittent current. The results indicated that the consolidation effect could be significantly improved and the unit power consumption for dewatering could be reduced with the proposed technique. An optimal anode length of two-thirds of the soil depth was recommended according to the experimental results. In addition, the intermittent current technique could also improve the drainage effect of soil submitted to electro-osmotic consolidation, and the combination of the two techniques has potential application in soft soil improvement.

In situ bioremediation is an attractive alternative compared to other methods used for treatment of contaminated soil and groundwater. There are significant challenges as well, such as availability of an electron acceptor, electron donor, nutrients and the presence of the appropriate microbial consortium in the contamination zone to biodegrade the target contaminant(s). The impact of these variables on aerobic and anaerobic microbial cultures is relevant when assessing the potential for successful implementation of such technologies. A mathematical model to tie these variables and environmental stressors is needed to better understand the microbial transport and activity in subsurface environments. Results from model sensitivity analyses and the uncertainty associated with microbial fate and transport phenomena are presented. Uncertainty analyses, using Monte Carlo simulation showed that for fine-grained soils, parameters relating to electrophoretic mobility and bacterial decay rate had the largest impact on microbial transport under low-strength electric fields.

Exposure to volatile hydrocarbons may lead to increased health risks. Consequently, there is an important interest in sensor development to detect and monitor the presence of these compounds, particularly at low concentrations. There are different kinds of detectors of volatile hydrocarbons (VHC), such as optical sensors, which have been developed by employing the phenomenon of evanescent fields for the detection of volatile organic compounds (VOC) such as hydrocarbons which include unclad, tapered and bendable fibers. However, the preparation of these fibers requires structural modification of the coating and therefore the sensor becomes fragile. These devices can only be used where there are no mechanical processes that may damage them. In this research, the optical detection of VHCs generated by electrokinetic treatment of polluted soil was evaluated. This evaluation was done by developing a fiber optic cable that was reduced in diameter to 20 μm and modified with a composite of Prussian blue and an acrylic polymeric emulsion to monitor the removal of hydrocarbons from soil when applying an electrical field.

The aim of the present work is to study the real applicability of the electro-bioremediation technology for the remediation of a diesel fuel polluted soil. Two tests were done: the first experiment used a real natural soil, polluted with diesel hydrocarbons at bench scale; the second experiment was identical but done at a higher pilot scale. It was found that the characteristics of the soil nature have determinant influence to extrapolate results obtained in the bench scale tests. It is suggested that the presence of natural species in the soil, constituting a complex matrix, could interfere in the biological degradation process of the diesel pollutant. Regarding the scale-up, it was observed that electro-bioremediation can be applied successfully at different scales and results show that it works, although the rates are strongly influenced by the size due to the very complex scale-up. The higher the scale-up, the greater are the operative problems that appear in the operation, such as formation of hollows, fissures, and dry areas.

The potentiality of the electro-kinetic remediation (EKR) system for the removal of hydrophilic and hydrophobic dyes contaminated kaolinite soil by finding the optimum conditions to obtain the higher percentage in dye removal, were investigated. A thiazine, an azo, and a triarylmethane dyes are representing hydrophilic dyes, while Sudan III from the Sudan series dyes representing hydrophobic dyes. An EKR tool (15 cm length) equipped with a DC electric current with the maximum values of 30 V. As a result, 40–55% of dye was removed from the soil sections by using distilled water. However, by the addition of some electrolytes; the percentage of dyes removed from the soil increased from 73 to 76% and 85 to 89% for sodium sulfate, and monosodium dihydrogen phosphate, respectively. It resulted that 55–64% of dyes was removed without controlling the pH. By controlling the pH in the cathode chamber, only 18%–25% of dyes remain in the soil sections, and by controlling the pH in the anode chamber, almost 90% of tested dyes could be removed from the kaolinite chamber effectively. It also resulted that Sudan III was given more better performance than methyl yellow 2. Around 70%–80 % of Sudan III removed from the soil sections by using o 1%, 3 %, 5%, and 7% concentration of SDS. It also found that anionic surfactant is suitable for removal of hydrophobic due to the ease of treatment and extraction process.

A former foundry operation and service station in northern Illinois is impacted with polycyclic aromatic hydrocarbons (PAHs) in soil. Site characterization and statistical analysis identified three PAHs – benzo(a)pyrene, benzo(b)fluoranthene, and dibenzo(a,h)anthracene – with concentrations exceeding their site specific remedial objectives in the upper three feet of soil. Project funding was not sufficient to allow for immediate site cleanup via excavation. Thus, a sustainable design was devised that relies on a combination of phytoremediation and potential limited hot spot removal in conjunction with institutional controls. In an effort to accommodate site specific challenges and short remedial timeframe of less than three years, a unique approach predicated on succession crops was developed.

Volatile organic compounds (VOCs) have been widely used in industrially developed countries such as Japan. Due to a variety of reasons, more than 100,000 sites in Japan are currently contaminated with VOCs, which require countermeasures. This paper provides a brief overview of the status of soil contamination in Japan together with remediation technologies for VOCs that cover physical, chemical and biological approaches. The concepts, mechanism, applicability and limitations of individual remediation technologies are summarized and discussed. Based on considerations of physicochemical properties of VOCs together with general characteristics of VOCs contamination, a strategy or framework for selecting feasible approaches and integrating different approaches for effective remediation is proposed. The systematic information and discussion in this paper may provide practical considerations and/or guidance for decision-making associated with the remediation of sites contaminated with VOCs.

Aldrin is an emerging and priority toxic pollutant attracting significant attention due to its global distribution, high persistence and bioaccumulation property. In this study, the degradation of aqueous aldrin by means of activated persulfate (S₂O₈^2-, PS) with ferrous ion (Fe²⁺) is investigated. The PS-Fe²⁺system achieved high levels of reduction capacity of aldrin. The effects of various factors including Fe²⁺ dosage, initial pH and molar ratios of PS/Fe²⁺ were established. The experimental results showed that aldrin is almost completely (99.9%) degraded in 180 min. with PS/Fe²⁺/aldrin molar ratio of 50/50/1. Degradation of aldrin is fitted with pseudo-first order kinetic model, and the rate constant is found to increase with increasing Fe²⁺ and PS molar concentrations, however decreased with increasing initial aldrin concentration. Degradation rate of aldrin is more favorable in acidic conditions in comparison with alkaline pH value. Aldrin and its degradation product (i.e. dieldrin) are identified by means of GC-MS spectral analysis. Additionally, simultaneous complete degradation of dieldrin with same experimental conditions of aldrin is perceived. In conclusion, iron (Fe²⁺) activated PS oxidation is a highly capable technique for aldrin contaminated ground water remediation.

The goal of this study is to understand the conditions in which heat collected from soil-borehole thermal energy storage (SBTES) systems can be used for thermally enhanced vapor extraction. Although thermal enhancement of soil-vapor extraction (SVE) has been investigated in several studies, they typically involved temperatures in the range of 50-400°C. The soil in SBTES systems typically only reaches temperatures of 40-60°C, which is not significant but is from a renewable source and can be applied for a long duration at low cost. The approach used in this study involves column tests in which a vacuum is used to draw air through an unsaturated soil layer that has a uniform initial diesel distribution. Three tests were performed in which the soil was heated to 20, 40, and 60°C and a vacuum was imposed to cause upward air flow through the soil column. The amount of diesel removed from the soil increased with temperature. Although up to 90% of the pore water was removed in the 60°C test, only a small fraction of the free-phase diesel was removed due to its low volatility. Nonetheless, the results indicate that combining SBTES systems with remediation strategies for volatile NAPLs may have a positive long-term impact on the reuse of contaminated sites.

To evaluate the air flow patterns under different surfactant-addition methods, a series of one-dimensional model tests were conducted in laboratory. The sodium dodecyl benzene sulfonate (SDBS) and river sands were selected as the test materials. Three kinds of model tests were performed including common pure air sparging (CPAS), surfactant solution-enhanced air sparging (SSAS), and surfactant foam-based air sparging (SFAS). It is found that SFAS has the highest air entry value, then CPAS, and the SSAS has the lowest value. Under the same conditions, SSAS has the highest saturation degree of air phase, then SFAS, and CPAS has the lowest value. The saturation degree of air phase of coarse grained sands is usually greater than that of fine grained sands. Surfactant enhancement can obviously improves the problem that channel number decreases with the increase of air flow rate. The air moves in a mode of channel flow in 0.5-1.0 mm sands, and bubble flow in 2.0-4.0 mm sands during air sparging. The surfactant introduction can decrease the size of air bubbles. In addition, surfactant foam moves more easily in coarse grained sands than in fine grained sands.

Recent regulations have given risk assessment a crucial role in the management of contaminated sites. In Tier 2 risk assessment procedures, often required by regulations, the migration of contaminants from the soil source towards the targets is modeled using analytical models and site-specific model parameters. Despite the use of site-specific parameters, some widely used models employed to simulate the volatilization of contaminants may significantly overestimate the emission of vapors from the soil, and, as a consequence, the exposure of human targets. The present paper describes the results of measurements of mercury vapor emission from the soil at an actual contaminated site. The measurements were carried out by means of open dynamic flux chambers. The results were compared with the predictions of widely used volatilization models, in which site-specific model parameters were used. Direct measurements of vapor emissions allow to overcome the simplifying assumption inherent to analytical models of contaminant migration and to take into account the volatile fraction of the contaminant of interest. The study pointed out that air temperature, pressure and humidity affect the vapor emission from soil; therefore, it is important to carry out surveys in different seasons.

Mechanical soil aeration is a simple, effective and low-cost soil remediation technique that is particularly suitable for soils contaminated by volatile organic compounds. However, low environmental temperatures, high moisture contents and high viscosity are associated with a severe tailing problem and thus significantly influence the remediation effect and duration. In this study, quicklime was used to remove chlorohydrocarbons including 1,2-dichloroethane, trichloroethylene and tetrachloroethylene from soils in an abandoned chemical plant site in China by using mechanical soil aeration. After 3% quicklime was added to the silty soil and silty clay during the tailing period, the concentration of residual contaminants decreased remarkably and quickly. The results showed that, firstly, quicklime can effectively enhance the remediation of chlorohydrocarbons in soil under mechanical soil aeration technique. Secondly, addition of quicklime changed the physical property of the soil and thus affect the environmental behavior of chlorohydrocarbons. Thirdly, Quicklime caused the changes of soil chemical property and thus influenced the removal of volatile chlorohydrocarbons in soils. The results provided basis for the application of mechanical soil aeration in remediation of chlorohydrocarbons-contaminated sites in broader scope.

This papers presents the experimental results of sorption of copper and desorption by surfactant from the pH-adjusted aqueous solution at varying initial concentrations onto a clayey soil through batch equilibrium. Soil sample for the experimental work was collected from non-vegetation depth through an open excavation. The pH range was varied from acidic to neutral ranging from 3 to 6 for experiments. By daily day wise observation for 10 days it was concluded that the concentration of copper metal remaining in the solution with time was non linear. Contaminants concentration was rapid for first 3 days and then its rate was slower for the rest of the days. A nonionic surfactant was tested for its desorption potential with different concentrations on the samples contaminated by copper, it was observed that desorption of metal occurs within 2 to 3 days and was found to be fairly effective with removal of more than 61.8% to 97.5%. The soil pH and variation in the time were the most important factors in controlling the removal of copper in remediation process.

In recent years, organic contaminants are receiving increasing attention due to their potential deleterious impacts to human health and the environment. Organic contaminants can easily migrate with the flow of groundwater and, depending on their chemical composition, can be extremely harmful to human bodies. Innovative remediation technologies with shorter remediation cycles, higher efficiencies and lower costs are urgently needed. Ozone is widely used in advanced wastewater treatment and remedial methods for the oxidation of organic pollutants, however the efficiency is limited by the fast degradation rate of dissolved ozone. Micro-nano bubbles can exist longer in water as compared with normal bubbles so that ozone can be provided constantly. In this paper, a combination of the micro-nano bubbles (MNBs) technology and ozonation was proposed for the treatment of an industrial site in Nanjing, China heavily contaminated by organic constituents. In the test, groundwater was extracted to be treated by ozone MNBs in bench-scale laboratory testing. Ozone MNBs showed remarkable ability in the remediation of contaminated groundwater. Based on the result of extraction test, in-situ remediation test was done in a 4 m × 4 m area. One extraction well and one injection well were used to form a extraction-remediation-injection system. The groundwater was treated with ozone MNBs and hydrogen peroxide for 3 h, and then the mixture was injected back into contaminated site. Three observation wells were used to measure the remediation efficiency of contaminants in the site. This study showed that ozone MNBs have potential application prospect in in-situ remediation of organic contaminated industrial sites.

In the age of rapid development and exploitation of water resources, the groundwater resources are not only dangerously depleted but also subjected to contamination due to various sources. To restore the contaminated aquifers using a best (or optimal) strategy, optimization models are often coupled with groundwater simulation models. The complex problem of groundwater contamination and its remediation is generally simulated by solving the governing equations of flow and transport by using numerical methods such as finite difference method (FDM), finite element method (FEM) or meshless method. On-site pump and treat method or in-situ barriers, chemical or bioremediation, etc., are some of the techniques which are applied for aquifer remediation. Further, optimization models like linear/non-linear programming, swarm intelligent techniques can be applied for cost minimization, pumping management and remediation. In this paper, details of simulation model using technique called meshless method and optimization technique using particle swarm optimization are discussed with the help of a case study for remediation of a hypothetical aquifer. Results from the proposed model demonstrate the effectiveness of such techniques and encourages applying them for other groundwater contamination remediation design plans.

The Passaic River, NJ is considered as the second most polluted river in the United States, where the lower 8 miles of the river is contaminated due to the heavily industrialization from the beginning of the 20th century. Over 100 industrial facilities have been identified as potentially responsible for discharging contaminants to the river, including, but not limited to, PCDD/F, PCB mixtures, PAH compounds, DDT and other pesticides, mercury, lead and other heavy metals. The USEPA has identified the lower 8 miles as superfund site and has proposed a remediation plan including dredging, dewatering and offsite disposal of the contaminated sediments. The objective of this study is to develop an in-situ remediation method using ozone nano-bubbles and ultrasound to treat the contaminated soil. Ozone is one of the most powerful oxidizing agents. A set of laboratory scale experiments are carried out using simulated dredged sediments from the Passaic River to identify the impact of sonication time, sonication power, pH in water and temperature on oxidizing PAHs. Once the baselines are established, the feasibility to use the proposed method for heavy metals and other organic contaminants will be examined. The data extracted from the laboratory experiments will be used to develop a field application of the technology. The observations from the pilot tests will be used to optimize the field application.

Although bioretentions have been proven to reduce stormwater runoff volumes and remove many pollutants, reports are variable as to the nutrient removal performance of this green infrastructure technology, pointing to the need for further investigation. In this work, the nutrient removal performance of six bioretentions in New York City (NYC)’s Bronx River Sewershed was quantified by identifying differences among dissolved nutrient concentrations in influent, infiltrate, and overflow liquid samples during 26 storms. Results indicate that the studied bioretentions are sources, rather than sinks, of nitrogen and phosphorus. Statistical analyses revealed higher levels of measured water quality indicators in the infiltrate of the bioretentions as temperature and the dry weather period before a storm increase, and lower levels of most indicators as the rainfall depth before sampling and the loading ratio of the bioretention increase. In this paper, the monitoring methods developed for evaluating the nutrient removal performance of the bioretentions are described, the data collected on bioretention nutrient removal performance is reported, and the statistical correlations between measured water quality indicators, local environmental conditions and the bioretention site properties are discussed.

A planned environmental remediation construction project in Northern California requires constructing a containment cover over existing dredge spoils deposited over a former marsh. Key geotechnical concerns with the cover construction include short- and long-term stability concerns and potentially large total and differential settlements. The soft subsurface soils include highly organic silts and clays (organic soils) and San Francisco Young Bay mud (YBM). Differentiation between these soils is critical for evaluation of edge stability and anticipated differential settlement across the site because the strengths and primary and secondary compression responses of the organics and YBM differ significantly. A 5-ton cone (calibrated for high sensitivity in soft soils) was used for cone penetration testing (CPT) during this investigation to enhance the resolution of the measured tip resistance and the associated friction ratio in an attempt to distinguish between the two materials. Using the 8 CPT/boring pairs, criteria were established to distinguish reliably between the organic soils and the YBM, and these criteria were extrapolated to 31 CPTs across the site to establish baseline site stratigraphy and material properties for use in design.

This paper presents results from a series of experiments which were conducted to assess engineering properties of lightly cemented very high moisture soil (VHMS). Dredged soil was collected from a dredged disposal facility near the port of Mobile, Alabama. Twelve different stabilized VHMS mixtures were prepared using two water contents (liquid limit and 100%), two cement types (portland-limestone cement and ordinary portland cement), and three cement contents (2.5, 5.0 and 10% of dry soil mass). A series of index and unconfined compression (UC) tests were conducted. UC tests were performed after various curing times to investigate trends of compressive strength with time. Specimens made with 2.5% cement showed no notable improvement of shear strength while higher cement contents (i.e., 5 and 10%) resulted in a meaningful improvement in shear strength. Results indicated that chemical cement reactions are controlled by the content of each component in the mixture. Further, UC results demonstrate an increasing trend of compressive strength with cure time as a result of hydration and pozzolanic reactions.

Large sediment remediation projects typically include extensive sampling and modeling to establish a remedial footprint that defines the horizontal and vertical extent of contamination that exceeds the remedial action level (RAL). For a sediment mega-site in the Midwest, the remedial footprint was initially established using a full indicator kriging (FIK) model to develop a 0.5 level-of-significance (LOS) surface for PCB contamination exceeding 1 milligram per kilogram (mg/kg, or part per million [ppm]). This modeling was very useful for establishing the contaminant footprint and elevation contours. The resulting model surface, core chemistry data, and design guidelines were used to create the design for dredging, capping and sand cover areas. Based on historical performance at this site, which includes over six years of dredging and post-dredge sampling, the FIK model performed well in areas with good data density and a lack of anthropogenic changes to the riverbed. If additional cores were obtained after the modeling was performed, readily-available software, Surfer in this case, was used to create an alternative elevation of contamination (EOC) surface that was patched into the LOS surface. This localized remodeling has been very effective in providing adjustments to the FIK model surface, and avoiding the need to remodel large sections of the river.

The sediment concentration is one of the important parameter in the area dealing with sediment transport. High sediment load is an integral component of Bhogdoi River, Assam, India and its role, despite being critical in the overall systemic behavior of the river, is little understood. Due to the sheer amount and the complex behavior of the sediment transport, its managements have remained a challenge. It is also essential to know the amount of sediment load carried by river system to manage it properly. In this study, an attempt has been made to estimate the sediment load by using artificial neural network (ANN) and multi-linear regression (MLR) models. For this purpose samples were collected from five different places and conducted laboratory test to know the physical and fluid properties of the sediments. In this study, it was preferred to implement a simple model to identify a direct mapping between the inputs and outputs without detailed consideration of the internal structure of the physical process. The main aim was to identify the best technique that could be adequately predicting the sediment load to a desired accuracy. The ANN and MLR was developed using 100 series of measured data, and data from Water Resources Department. ANN was developed using RBF network and also compared with results of MLR models. The result obtained by ANN model gives better prediction than the regression model.

A geotechnical characterization of sediments in the wetlands of coastal Louisiana was carried out using settling column tests and a portable free-fall penetrometer (PFFP). The laboratory and in-situ results from three sites in Lake Borgne and the Terrebonne Parish were compared, and the interpretation was complemented by a geotechnical and geochemical laboratory analysis of the sediment. The results revealed that a higher organic content (10.4%) led to a lower consolidation of the material in the settling column tests, as well as a lower in-situ seabed strength. A higher content of coarse particles (41%) resulted in a quicker consolidation, particularly on the first of the fifteen settling column test days. This was also correlated to a steeper increase of sediment strength with sediment depth in the field. A significant deviation between the two tests was the presence of a 6-20 cm thick loose top layer at the seabed surface that was only observed in the field. This was likely related to ongoing sediment dynamics. As no storms or heavy rainfalls preceded the experiments, wake waves in response to boating activities may be considered as an explanation for the limited consolidation of sediments at the seabed surface.

Capping is commonly used for remediation projects for contaminated subaqueous sediments. Placement of cap material over sediments poses challenges to the geotechnical stability of the cap and underlying sediments and requires knowledge of geotechnical engineering properties for detailed design and analysis. Sediments often encountered in capping projects are very soft, which makes collection of undisturbed samples for laboratory testing practically impossible. Because capping projects commonly cover a large area, spatial variation of subsurface conditions and geotechnical properties is significant. Conducting a comprehensive geotechnical field investigation can be difficult, time-consuming, and expensive. This paper describes various in situ geophysical and geotechnical site investigation techniques that can be used to establish geotechnical properties in order to evaluate the stability of cap placement. An example of an integrated study incorporating in situ geophysical and geotechnical investigations for a capping project is presented. A discussion of how the subsurface investigation data can be used for evaluating the cap stability is also included.

In the world, millions of cubicmeters of materials are dredged from sea or channel bottoms each year. It is both uneconomical and dangerous for the environment, when dredged materials are considered as waste and stored at the landfills or discharged at the offshore areas. For that reason, studies on the sustainable usage of dredged materials, which has high water content or organic matter, increase especially at fills, structural materials and topsoils. Generally one or two different chemical additives (lime or cement) were used with different proportions and water contents. In this study, a dredged soil from İzmir Bay was selected and the optimum combination was determined for compaction characteristics and durability. The standard Proctor test results have shown that, in the presence of 7% lime and cement the maximum dry unit weight of the samples were 1.75 and 1.65 g/cm³, respectively. However, when 3.5% lime and 3.5% cement were mixed and used together, the maximum dry unit weight became 1.72 g/cm³. In the second part of the study, the strength properties of the modified dredge material with lime and fly ash were determined in the presence of distilled water and natural seawater for their potential usage in onshore fills. Optimum lime and fly ash contents in terms of strength were determined for the Izmir Bay dredged soil by unconfined compression tests. The test results also revealed that dredged soil specimens treated with sea water had systematically greater unconfined compressive strengths than that of their distilled water counterparts.

Dredging creates geo-disturbances to the formations. This geo-shock modifies the geotechnical properties of the original formation. Soil location, area, classification and moisture content are primary drivers of the dredging activity. In this chaotic condition the effect of water content (moisture) in the dredged materials is considered in four stages. In the first stage the effect of water (hydrolysis) in the evolution stage of clay minerals and their weathering processes before dredging is discussed. In the second stage the documented and published research papers which deal with moisture content variation (low, medium or high) on clay minerals are analysed. In the third stage a conceptual model of three layer system with equal thickness consisting of kaolinite, illite, and montmorillonite with different sequences after placing dredged materials is considered. In the fourth stage the effect of torrential rainfall on different sequences of layers is considered and linked to consolidation settlement and differential settlement, to bring out multi-disciplinary approach to solve complex soil/dredged sediments problems. The shrinkage indexes of clay minerals play a major role in deciding the stability and geo-technical behaviour of dredged sediments.

Sediment (mud and sand) from man-made diversions of the Mississippi River, dredging effluent, and other sources is being used to conserve and create land to protect the Gulf Coast. The long-term settlement prediction of these newly deposited sediments is necessary to ensure the confined dredged disposal areas, coastal restoration, and marsh creation projects protect people and their property, wetlands, and various infrastructure over the design/service life. Long-term settlement predictions are usually made with the software Primary Consolidation, Secondary Compression, and Desiccation of Dredged Fill (PSDDF). PSDDF is a 1D nonlinear numerical model that accounts for settlement due to self-weight and surcharge induced consolidation, secondary compression, and desiccation. This paper uses a hypothetical case study to estimate the dredged fill height necessary to maintain a surface elevation of 1.5 ft for the next 20 years. Because there is uncertainty in the hydraulic conductivity and compressibility relationships, a reliability analysis is performed to quantify the effect on long-term settlement predictions. The uncertainty analysis indicates that the void ratio-effective stress and void ratio-permeability relationships influence the surface settlement more than the other input parameters for the dredged sediment.

Soil mixing has been utilized in the geotechnical field for over 40 years, primarily for the construction of foundation support elements. Soil mixing was first applied to environmental applications over 30 years ago, beginning in the mid 1980’s. Increasingly, soil mixing is being used in the United States to cost-effectively isolate, stabilize or treat a range of contaminated soils in a variety of applications. This paper presents a summary of some of its early applications, including the U.S. EPA Superfund Innovative Technology Evaluation (SITE) program, containment applications for chemical warfare material (CWM), and the widespread commercial development of this technology in the solidification and stabilization (S/S) of highly impacted soils as an alternative to off-site disposal. Recent advances include the trend for in-situ treatment of impacted soils via in-situ chemical oxidation (ISCO) and in-situ chemical reduction (ISCR). Finally, the newest application of soil mixing for the in-situ treatment of impacted sediments beneath our lakes and rivers is discussed.

The immobilization potential of dissolved Cd and Zn (each ~750 mg/L) in independently packed columns of freshly crushed steel slag fines (SSF) media was evaluated. The SSF media was characterized as USCS SP type soil with <5% passing the No. 200 (0.075 mm) sieve and the flow rates were on the order of a meter per day with a residence time on the order of 3.5 hours for a 25-cm long column containing approximately 5 kg of SSF media. The influent pH of the Cd and Zn solutions were on the order of 5.8 and 7.2, respectively, and the pH of the effluent for the test duration of 100 pore volume (PVs) remained above 11.5. The dissolved concentrations of Cd in the effluent remained below the detection limit (0.05 mg/L) for the entire test duration; whereas the Zn concentrations exceeded 1 mg/L at approximately 48 PV. Independent acid neutralization capacity (ANC) testing of Cd- and Zn-spiked SSF media (~500 mg/L each) coupled with geochemical modeling indicated that Cd was insoluble within the SSF. Similar trends were initially observed with the Zn testing suite, except that the aqueous solubility minimum of Zn occurs near pH=9; and its amphoteric behavior above that pH value meant it prematurely broke through the packed SSF column.

The primary objective of this paper was to investigate vegetation establishment in lightly cemented very high moisture content fine grained soil with or without geotextile tubes. This material’s intended purpose would be, for example, making use of dredged material to produce land adjacent to a port that can blend into the natural environment. A literature review indicated that there is an increasing interest in engineering with nature (or working with nature) concepts as several works were cited in the past five years, but none of them incorporated cement. After review of literature, an experimental program was reported where soils from two dredge disposal facilities were utilized in conjunction with a synthetic geotextile, two types of grass seed, and portland-limestone cement (a more sustainable alternative to portland cement). Several outdoor experiments were performed to determine vegetation establishment viability. Test results showed established vegetation, thus demonstrating viability of combining vegetation with portland-limestone cement.

Process stabilization–solidification (PSS) is a convenient technology for amending high water content dredged sediments (DS) with binders. The PSS equipment comprises of a chassis that carries a pugmill and silos of up to four binders. Primary binders such as cement can be supplemented with pozzolanas materials. In this study, physicochemical interactions of single and composite (ternary) binders on strength development of treated DS are examined based on laboratory and a large–scale field tests. The findings of this study show that the unconfined compressive strength (UCS) depends on the amount of cement in the blend. The UCS decreased with increasing water/cement ratio. It is concluded that (i) the use of constant amounts of composite binder at increasing initial water content of the DS contributes to increased water/cement ratio. (ii) Underwater discharge of stabilized DS prior to the initial setting increases the water/cement ratio of stabilized mass. (iii) Presence of mineral admixture hinders strength development of treated dredged sediments.

Solidification/stabilization (S/S) technology has been widely used to remediate contaminated soils ex-situ and in-situ. A case study of treating VOCs and SVOCs contaminated soils using S/S technology is presented here. The site used to be a chemical factory, is located in Nanjing, China. 6 types of binders are used and moisture content test, soil pH test, leaching test and unconfined compressive strength test (UCS) are carried out. The moisture content results indicate that all binders have an insignificant effect of reducing the water in contaminated soils. The addition of binders can increase the soil pH which decreases with curing time. The leaching characteristics indicate that the immobilization percentage of organic contaminants is affected by binder type and curing time. The UCS results show that the development of q_u depends on the nature of binders. Moreover, contaminated soil treated with Portland cement-Attapulgite (PC-AT) and Portland cement-MgO (PC-MgO) gets the highest q_u at 28 days.

Stabilization/solidification (S/S) technology has been wildly utilized in remediation of contaminated soils. It is sustainable to reuse S/S treated soils. This paper presents a study of the reuse of S/S treated soils as greening soils. The virgin soil is heavily contaminated with lead, zinc and cadmium. Two S/S binders (KMP and MC) study are modified to meet the demand of a neutral pH and low salinity-alkalinity environment after remediation. Synthetic precipitation leaching procedure (SPLP) test is taken place to evaluate the leaching characteristics of the two loam-mixed stabilized soils. The germination index (GI) and pot trials are used to assess the phytotoxicity of the loam-mixed stabilized soils. The results reveal that after the treatment, heavy metal concentrations of the leachate, the phytotoxicity of the KMP stabilized soil decrease remarkably to an acceptable level. The pot trial shows that there is no suppression on the cabbages cultivated in the KMP stabilized soil.

This paper presents the results of an experimental study on the chemical, leaching and strength properties of VOCs and SVOCs contaminated slurry using cement, attapulgite, and sand as binders. Toxicity characteristics leaching procedure and unconfined compressive strength tests are used in this study. The results suggest that the slurries stabilized/solidified with four binders all display strong basicity, among which slurries stabilized with B1 (cement) and B3 (cement + sand) show relatively higher pH values than the other binders tested in this study. In addition, slurries stabilized with attapulgite-based binders (B2 and B4) behave like a ductile material. All four binders can effectively reduce the concentrations of target VOCs and SVOCs leached from slurries, and B1 and B3 obtain higher immobilization percentages than the other binders tested in this study. The result of this study also indicated that the unconfined compressive strength of stabilized slurry increases considerably with time, and has a good correlation with both EC and pH of stabilized slurry.

Utilization of waste sawdust ash to enhance the engineering properties of soil and the beneficial reuse of contaminated soils would foster environmental sustainability in developing countries, especially Nigeria. This research investigates the safe reuse of crude oil contaminated sandy soil in highway pavement construction application. Sandy soils (Patani sand) sampled from the Forcados River in Niger Delta, Nigeria and were artificially contaminated with crude oil from Afisere Flow Station Delta State, Nigeria. An innovative and traditional binder mix, saw dust ash-cement (SDAC) mixed in the ratio of 2:1, was added to aged contaminated sandy soil at 5% and 10% by weight. Strength, environmental performance evaluation and microstructural tests were performed on the samples to evaluate the strength characteristics and environmental suitability of stabilized crude oil contaminated soils (COCSs). The strength evaluation tests include California bearing ratio (CBR), unconfined compression and direct shear tests. The soaked CBR value increased from 41% - 57% when stabilized with 5% SDAC and from 58% - 79% when stabilized with 10% SDAC. The leaching of a selected sample (COCSs) stabilized with 10% binder over a period of 90 days, shows the reduction of leachate TPH from 66.25mg/l after 7 days to 47.38 after 90 days.

This paper describes the process Delta Institute’s project team used to obtain and directly integrate a community’s goals and needs into an engineering-based, brownfields prioritization rubric. A two-phased approach was used to prioritize sites. Phase I reduced the initial brownfields inventory from 62 to 20, relying upon a quantitative rubric to score the community’s inventoried brownfields by assessing both site-related data and community site redevelopment goals. This initial approach was only partially successful and as such was supplemented with an alternate qualitative, community-based comparison process. Phase II reduced the interim list of 20 sites to ten. This approach began with a re-scoring of sites to produce refined, site marketability scores and summaries that were then used to inform a more time intensive, flexible, and individualized community and stakeholder engagement process. Phase II resulted in significant community input on desired reuse of the sites to reduce the number of sites to ten. Delta Institute found that while the original engineering-based approach (scoring rubric) brought significant value to the project, the more qualitative, individualized community engagement approach in Phase II resulted in a site prioritization that more truly reflected the goals of the community in an impactful way.

The Brazilian national policy on solid waste was regulated in 2010 and sets out a hierarchy of sustainable solid waste management actions: first, no generation, then reduction, reuse, recycling, treatment and finally, the environmentally adequate final disposals of municipal solid waste (MSW) “MSW refuse”. This policy also previews the universalization process of the sanitation services in Brazil and the closure of all existing dump sites in capital and metropolitan municipalities until 2018. However, the environmentally appropriate waste management process is not in course as defined by law. This process has been shortened in practice, and solid waste has been directly deposited at the sanitary landfills or old dump sites of the smallest cities. This study aims to present the real possibilities of reducing the generation of MSW refuse in the municipality of São Paulo and to illustrate the sustainable technologies and actions applicable to the São Paulo case at every stage of waste management, minimizing the amount requiring disposal at the sanitary landfills, as MSW refuse.

Nanomaterials have become ubiquitous in consumer products and industrial processes and represent an emerging waste stream with significant increases in disposal quantities expected. The fate and transport of nanomaterials in the environment have not yet been fully understood. An extensive study is conducted to broadly incorporate environmental impacts of nanotechnology into the curriculum at Cal Poly. A component of the study related to development of cross-disciplinary learning activities between geotechnical/geoenvironmental engineering courses and courses from other disciplines including environmental engineering, materials engineering, and political science is described herein. The learning activities focused on synthesis of nanomaterials with regard to material and product performance (materials engineering), with regard to fundamental soil behavior in response to nanomaterials (geotechnical engineering), with regard to fate and transport of nanomaterials in the environment (geoenvironmental engineering), and with regard to societal and regulatory issues (political science). In addition to courses from different disciplines, courses of different levels were included in the cross-disciplinary learning activities. Students in the impacted courses gained experience in collaborating with their peers from other disciplines as well as comprehended the requirement for integration of various technical and nontechnical perspectives in providing solutions to complex geoenvironmental problems.

In recent years, the U.S. Department of Energy (DOE) has constructed waste disposal facilities (WDFs) at a number of their sites for the management and disposal of waste generated during Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) remediation activities, including environmental remediation (ER) generated wastes and decontamination and decommissioning (D&D) wastes. DOE has used the CERCLA process at a number of these facilities for decision making on whether to dispose of CERCLA wastes at an off-site disposal facility or in a newly constructed on-site WDF. Somewhat unique to these WDFs is the number of federal regulations, orders, and other potentially applicable or relevant and appropriate requirements (ARARs) that drive the design approach. This paper discusses differences between the various requirements and describes how they are integrated to develop a coherent design philosophy and package of design criteria.

The authors describe experiences in implementing an interdisciplinary research experiences for undergraduates (REU) site sponsored by the National Science Foundation. The site was administered by principal investigators (PIs) from the Civil and Environmental Engineering Department and the Global Waste Research Institute (a co-sponsor of the program) at Cal Poly, San Luis Obispo. The REU program specifically encouraged and promoted interdisciplinary work through project and participant selection. Over the past three years, the PIs recruited participants from varied undergraduate disciplines including civil engineering, environmental engineering, biological engineering, biology, chemical engineering, chemistry, mathematics, and mechanical engineering. These participants have undertaken projects focused on beneficial reuse of waste products, solid waste landfill performance and modeling, energy production from wastes, nanowaste materials, and waste treatment, among others. The projects illustrated the importance of team knowledge and understanding related to various technical and professional skills when solving geoenvironmental challenges. The varied backgrounds of the participants as well as the mentors allowed for successful completion of the projects.

Introducing sustainability concepts into geotechnical education makes good sense since civil engineering projects are energy intensive and geotechnical engineers are involved early in civil engineering projects. There are two major deterrents for incorporating sustainability concepts: the majority of the 240 ABET accredited Bachelor of Science in civil engineering programs require only a single geotechnical engineering course and students must be introduced to fifteen geotechnical topics to be adequately prepared for the FE exam. Geo-sustainability is presented as four independent categories of geo-planning, optimization of the underground environment, effective and innovative use of geo-materials and natural hazard mitigation. Each category is described and examples are provided. Comparing the geotechnical engineering topics of the FE exam and geo-sustainability examples from each geo-sustainability category, it is possible to introduce sustainability concepts into a single geotechnical engineering course while still coving all FE topics. Some geo-sustainability concepts must be introduced as lecture topics while others can be introduced as problem solving exercises.

The importance of educating future generations of engineers with respect to sustainability is becoming increasingly obvious. At the U.S. Coast Guard Academy (CGA), the engineering faculty recognize the need to educate the future of our service and have developed a variety of classroom approaches to ensure students fully understand the role that climate change and sustainability play in their engineering decision making process. As a sea-going service, most of the U.S. Coast Guard (USCG)’s assets are along coastline. As the USCG’s primary civil engineering accession point, ensuring future engineers are exposed to the potential challenges that may arise due to rising sea level, predicted water shortages and changes in the availability of energy resources is an issue of readiness. Concepts of sustainability have necessarily been infused into CGA’s undergraduate engineering curriculum. The manner in which sustainability has been taught in several undergraduate courses within the civil engineering program at CGA is discussed. Teaching methods utilizing various pedagogies have been employed to ensure that graduates understand the complexity of the issues surrounding the ecological changes facing the planet while also providing a solid understanding of the practices of sustainability and the need for the education of future generations on the topic.

Status of two types of contaminated sites in India are presented, municipal solid waste (MSW) dumps in cities with population above one million and sites where subsoil is contaminated by hazardous solid waste and effluents near industrial areas. Heights and base areas of 62 dumps in 26 cities range from 2 to 29 m (i.e. 6 to 95 ft) and 2 to 53 ha (i.e. 5 to 130 acres) respectively (interquartile ranges). These dumps have potential for impact since 62% of the sites are less than 500 m from the communities, 85% of the sites have groundwater (GW) at less than 25 m depth and 40% of the sites have surface water bodies within 2 km distance. Areas of sites contaminated by hazardous waste range from 0.11 to 6.6 ha and primary contaminants of concern are heavy metals, hexavalent chromium, hydrocarbons and others. Policy initiatives being taken at the national level to remediate and control such dumps and contaminated sites are highlighted.

This paper discuss the effect of best water use ethics as a tool for sustainable water management in the Arab region. Several studies have focused on the technical and scientific dimension of water management compared to the social and soft dimension. The paper utilizes combination of cultural, ethical, and social marketing that is propagating social learning from basic education levels to raise the ethical aspects of water use management. Such approach is very needed in the arid region were water is very scares like most of the Arab region. Water resources availability has been a major constraint on social and sustainable development in the Arab region. The paper discusses the complexity of the Arab water crisis and the role of the ethical and cultural values in developing a shift in the "Arab water vision" 2025. It explains how best water ethics could contribute to its realization to ensure sustainability through a social and ethical conduct. It investigates new tools and techniques based on participation of relevant stakeholders in decision making, knowledge and experience transfer among water institutions and organization, and through reviving best ethical practices in the Arab region.

A comprehensive list of key topics covered by environmental geotechnics can probably be written by specialists in the field without much disagreement. However, there is arguably less certainly about what a university course on the subject should include and, even less, what balance of theory, experiments, design and field work it should entail. The paper reports the author’s ongoing experience in designing and teaching a course on environmental geotechnics/geoenvironmental engineering at the school of civil engineering of the University of Sydney, over the last six years. The course is set at a graduate level but open to final-year undergraduate students as well. Questions of content and teaching approach, as well as issues of how best to help students learn fundamental concepts such as Darcy velocity, diffusion, advection, and mass flux are tackled.

This paper presents the outcome of a research program aimed at investigating migration and interaction mechanisms of saline and acidic sulphate solutions through cement-bentonite mixtures with the main aim to estimate their long-term hydraulic performance and durability. A method to evaluate the mixture durability is proposed, based on the results of several column tests performed with different solutions for long times (up to about 5 years).

Elevated levels of arsenic that leach from mine tailings, sediment and soil can lead to the contamination of surface and groundwater. In this study, various types of metal oxides as immobilizing agents were evaluated. Their effectiveness was determined via leaching tests and selective sequential extraction (SSE) using mine tailings and metal oxides at different weight ratios, reaction times, and types of oxides. Commercial grade metal oxides (MgO, ZnO, Fe₃O₄, TiO₂, CaO and Al₂O₃) in the form of regular and nanoscale powders were evaluated. Both forms of ZnO (zinc oxide) had a higher capacity to immobilize the arsenic present in the mine tailings than any other oxides tested. Magnetite (Fe₃O₄) had limited effectiveness whereas all other metal oxides tested had little or no effect. The addition of 7.5% by weight of nanoscale ZnO led to a 99.4% to 99.7% reduction in the amount of arsenic leached from Noranda and Golden Giant mine tailings after 24 h in an acidified water solution at a pH of 3. SSE tests confirmed that ZnO is a very effective immobilizing agent in all five fractions. These results indicate the possibility of developing a remediation process for mining areas as well as other contaminated soils using ZnO.

Both a coated and laminated GCL from the same manufacturer are examined with respect to the interface transmissivity between the geofilm and a smooth 2.0 mm HDPE GMB. The laboratory apparatus and test methods are described. The results obtained from the interface transmissivity tests conducted under vertical stress of 150 kPa and hydraulic head of 1.2 m are reported. The preliminary results suggest similar low interface transmissivities to water of 1.2x10^-11 m²/s and 1.3x10^-11 m²/s for the coated and laminated GCLs.

Electro-osmotic consolidation is an effective technique for soft soil improvement. In this study, a multi-field coupling numerical model for electro-osmotic consolidation was proposed to simulate the dewatering and consolidation process of soft soils. Seepage, electrical, and stress and strain fields were considered and the boundary conditions could be adequately simulated. Two cases were studied and compared with the numerical results to verify the effectiveness of the numerical model. The numerical results showed good agreement with the field measurements. The intermittent current and polarity reversal conditions were simulated and exhibited significant influence on the development of settlement. The surface settlement could be more uniform with the application of polarity reversal method. The complex field conditions can be simulated, and the electro-osmotic consolidation process can be predicted by means of the proposed numerical model.

The use of robots for surface methane concentration (SMC) monitoring at municipal solid waste (MSW) landfills has the potential to improve quality of data acquisition for fugitive methane measurement over current practices. Methane concentrations vary significantly, both spatially and temporally, across a MSW landfill. However, current monitoring methods do not necessarily account for these significant spatial variations. A land-based robot coupled with commercially-available, relatively low-cost methane detection technology for SMC monitoring was field tested at an active MSW landfill. To more effectively monitor fugitive methane emissions at MSW landfills, an automatic, low-cost, field-deployable technique is needed to actively monitor methane concentrations. Three test areas within a landfill were selected; SMC surveys were performed both manually and by land-robot using the Landtec TDL-500, a tunable diode laser methane detector. The preliminary field observations indicate that a robotic platform can significantly improve quality in data acquisition for surface methane concentrations at MSW landfills; this paper also discusses the limitations of land-based robots for site-wide methane emission monitoring.

One of the most important activities when preparing a land reclamation project of brown fields is a comprehensive analysis and documentation of subsoil conditions at the site. The paper presents the site investigation methodology applied for the purpose of preparing land reclamation project of a metallurgical solid waste landfill, located in a close vicinity of a developed big city in the central part of Poland. The landfill was a part of a steel factory facilities where combustion by-products have been disposed since 60’s, without any protection systems. The paper also presents range and methodology of contaminated soil survey, waste morphology and composition analyses as well as documentation of obtained results. The research consisted of both, site investigation and laboratory tests. A detailed analysis of the results allowed precise determination of soil contamination indicators, environmental impact zones, and volumetric capacity of contaminated soil. On the basis of methods such as geoelectrical tests, boreholes, geodetic surveys and laboratory chemical analyses of samples, several maps of contamination impact zones were prepared, which at the final stage allowed completing a complex brown field reclamation plan.

Geothermal energy piles exploit the almost constant ground temperatures at given shallow depths below the ground surface to heat or cool built structures through the use of a heat pump. In such an event it is not only the heat distribution within the soil that is affected but also that of the moisture. This paper presents a preliminary investigation on the influence of intermittent and continuous operating modes of a model geothermal energy pile on the soil temperature and moisture content. Experiments were conducted for a 24 hours continuous operation, 16 hours operation with 8 hours rest, and 8 hours operation with 16 hours rest. The largest change in soil temperatures and moisture content was recorded closest to the pile and tended to reduce with increasing radial distance for all operating modes. The results obtained from this study indicated that intermittent operation with longer recovery time periods had lower effects on the soil temperature and moisture content variations.

Design and construction standards of landfills in Victoria, Australia, are subject to specific, outcome-based, liner performance criteria in accordance with the landfill guidelines known as the Best Practice Environmental Management Guideline (Siting, Design, Operation and Rehabilitation of Landfills) (BPEM). Consequently, landfill design and construction standards in Victoria have significantly improved with strictly applied construction quality requirements. The design documents for every new landfill (or landfill cell) need to be approved by the Environment Protection Authority (EPA), the Victorian government regulator, prior to commencing construction. The design documents must include plans, technical specifications and a construction quality assurance (CQA) Plan which are prepared in accordance with the BPEM. In addition to the design documents requiring assessment, the construction needs to be audited by an EPA appointed environmental auditor. While these measures have contributed towards the achievement of highly successful outcomes, these efforts are at times hindered by certain actions - or lack thereof – and have resulted in a number of problems at some landfill sites. Such problems include the inappropriate selection of materials in landfill construction, inappropriate use of vehicles and machinery, the way landfill operation is conducted, the lack of communication and the inexperience of construction staff. While all these problems have been identified and successfully addressed through the EPA’s environmental auditing system, such incidents have the potential to hinder improvements in design and construction standards, lead to additional costs and time, and result in increased frustration for all involved. This paper will discuss several of the construction problems which have occurred at certain landfill sites in Victoria and how such incidents have been addressed to ensure appropriate and effective design and construction standards are achieved.