Aquifer vulnerability assessment using the DRASTIC model at Russeifa landfill,northeast Jordan

Groundwater is inherently susceptible to contamination from anthropogenic activities and remediation is very difficult and expensive. Prevention of contamination is hence critical in effective groundwater management. In this paper an attempt has been made to assess aquifer vulnerability at the Russeifa solid waste landfill. This disposal site is placed at the most important aquifer in Jordan, which is known as Amman-Wadi Sir (B2/A7). The daily-generated leachate within the landfill is about 160 m³/day and there is no system for collecting and treating this leachate. Therefore, the leachate infiltrates to groundwater and degrades the quality of the groundwater. The area is strongly vulnerable to pollution due to the presence of intensive agricultural activity, the solid waste disposal site and industries. Increasing groundwater demand makes the protection of the aquifer from pollution crucial. Physical and hydrogeological characteristics make the aquifer susceptible to pollution. The vulnerability of groundwater to contamination in the study area was quantified using the DRASTIC model. The DRASTIC model uses the following seven parameters: depth to water, recharge, aquifer media, soil media, topography, impact on vadose zone and hydraulic conductivity. The water level data were measured in the observation wells within the disposal site. The recharge is derived based on precipitation, land use and soil characteristics. The aquifer media was obtained from a geological map of the area. The topography is obtained from the Natural Resources Authority of Jordan, 1:50,000 scale topographic map. The impact on the vadose zone is defined by the soil permeability and depth to water. The hydraulic conductivity was obtained from the field pumping tests. The calculated DRASTIC index number indicates a moderate pollution potential for the study area.     

Geochemical characterisation and geophysical mapping of Landfill leachates: the Marozzo canal case study (NE Italy)

An integrated approach including geochemical analyses and geophysical investigations, aimed at characterizing the chemical composition of leachate and at highlighting the extent and magnitude of the plume in terms of spatial distribution is presented. The reason for the specific induced polarisation behaviour over landfills was not well understood. In this work we propose an explanation for this behaviour, which is being used to detect the presence of possible leaks and to track and delimit the pollution plume for several years.As a case study the example of an abandoned municipal solid waste landfill, located in Comacchio County, NE Italy, is presented, where the operative conditions for any resistivity monitoring method were to be excluded because of the high salinity of the phreatic aquifer.     

Urban Waste Disposal and Its Impact on Groundwater Pollution in China

Waste production in cities is increasing with growing urbanization in China. As the incorrect disposal of waste can lead to environmental problems and pollution of groundwater, it is important to asses the suitability of sites for waste disposal. In this paper, 831 waste disposal sites in 295 cities in China were investigated, and suitability assessments of 508 sites were made. The results showed that the number of “suitable”, “moderately suitable”, “barely suitable” and “unsuitable” waste disposal sites accounted for 17.7%, 29.5%, 14.2% and 38.6% of the sites investigated, respectively. The pollution condition of 465 sites was examined, and the results indicated that groundwater in 282 sites was contaminated. Groundwater samples from two polluted sites were collected and analyzed to inform a proposal on urban waste disposal.     

废物地质处置中的水文地质问题分析

废物地质处置中废液的泄漏或固体废物渗滤液对地下水可能产生的污染影响是选址中一个必须考虑且不可忽视的基本水文地质问题.分析了地下水污染中的几个基本概念问题, 并就废物地质处置选址和设计中如何注意这些问题提出了相应的解决办法及对策.      

Geochemical modeling and low-frequency geoelectrical methods to evaluate the impact of an open dump in arid and deltaic environments

In Mexico, open dumps that are maintained by the municipality but provide no covering of waste are not uncommon. Further, disposal at these sites is often performed by burning. The aim of this study was to determine the leachate plume from an open dump located in a depositional deltaic environment, with arid climate, low rainfall and where the water table is about 2 m below the surface. The methodology comprised analysis of groundwater monitoring wells and geophysical and geochemical prospecting techniques. The 3D geoelectric interpretation shows a typical area of these depositional environments with low resistive values (10–20 Ω-m) associated with the presence of sands and clays interbedded. However, there is a very low resistivity zone associated with the dump’s impact which reaches values below 5 Ω-m, and it is located where the disposal and burning of wastes occurred. Another zone with values above 16 Ω-m appears as a limit for the advance of the saline. This is interpreted as a sandy lenses area. These sandy lenses with higher porosity transport aquifer’s water. Thus the dump is in direct contact by this conduct with clean groundwater. Piper diagrams constructed with the chemical data analysis reveal that the groundwater in the area corresponds to the chlorinated and/or sulfated sodium type, showing the impact caused by the dump. The monitoring well (NP8, on-site) with the highest dissolved solids content behaves anomalously and belongs to the more conductive zone according to the geoelectric profiles. The subsoil geochemical behavior is influenced by the seasonal water table variations provoking the dissolution of burned and unburned wastes, but the effects of slow flows in the direction of the regional flow are not discarded. Although the most impacted area within the dump is characterized to a depth of 10 m, there is a slow flow in the direction of the regional flow that has been moving pollutants out of the dumpsite during its almost 20 years of operation. The results of this study provide valuable information for the authorities to carry out an appropriate restoration project.     

Identification and mapping of chromium (VI) plume in groundwater for remediation: A case study at Kanpur,Uttar Pradesh

With only twenty five percent population living in urban areas, India has cities amongst the biggest in the world. Urban growth in most of Indian cities is concomitant with rise in water demand for community, as well as, for industrial purposes. The complex situation resulting from indiscriminate disposal of waste and its severe impact on groundwater quality is set for continuous worsening mainly for want of sustained effort aimed at site-specific remediation. The study, a prerequisite for actual remediation in an industrial city of Kanpur, India, envisages detailed investigation about pollutant transport, evaluation of concept of Bio-remediation and a range of other options and finally full scale implementation of the best suited. Drilling of piezometers and resistivity survey indicates that the area is constituted of alluvial sands, gravels and their various admixtures. Chemical analysis of water samples collected from piezometers and hand pumps shows the presence of hexavalent chromium rich horizons at various depths. The alarming concentration of this carcinogenic heavy metal of the order of 16.3 mg/l against the permissible concentration (of 0.05 mg/l) for drinking water and high concentration within sediments of the area poses a major threat to the entire ecosystem. The projection of migration contaminant plume of hexavalent chromium as depicted in the paper is indicative of a concentrated extent of core zone existing in shallow alluvial aquifer, which may be targeted for interception by remedial measures. The present work, elaborating on the source, potential and monitoring the migration of the pollutant plume is the first field scale study of its kind in the country. The findings of these studies are of strong relevance in addressing the ground water pollution due to indiscriminate disposal practices of hazardous waste in areas located within the alluvial zones.     

Evaluation of waste disposal site using the DRASTIC system in Southern Korea

As a systematic approach to waste disposal site screening for groundwater pollution protection, the DRASTIC system developed by the US Environmental Protection Agency (USEPA), was introduced at Younggwang County in Korea. Hydrogeological spatial databases for the system include information on depth to water, net recharge, aquifer media, soil media, topographic slope, hydraulic conductivity and lineament. Using the databases, the DRASTIC system and a GIS, the regional groundwater pollution vulnerability of the study area was assessed. The fracture density extracted from lineament maps was added to the DRASTIC system to take into account the preferential migration of contaminants through fractures. From the results of the study, a degree of groundwater pollution vulnerability through the study area was easily interpreted, and waste disposal sites could be screened for groundwater protection.     

Behavior of a municipal landfill from field measurement data during a waste-disposal period

The behavior of a municipal waste landfill on marine clay was analyzed from field measurement data. Instruments, e.g., a groundwater level sensor, piezometer, earth pressure gauge, settlement plates, inclinometer, etc., were installed and operated during the disposal period from October 1992 to November 2000. A database system was developed to manage the data from this landfill using Access (Microsoft) with Delphi programs. From the analyses, it was determined that the settlement of the landfill during the initial period of waste disposal was small because of the high leachate level in the landfill. As the level of waste became higher than the leachate level, the settlement of the landfill increased significantly due to the increasing effective pressure within the landfill. From a stability point of view, the critical time for the landfill in this study was the initial period of landfill disposal, which was caused by either the impact load of waste disposal or the time schedule of waste disposal, which was faster than the consolidation of foundation clay caused by the waste load.     

Geochemical investigation of groundwater contamination in Perungudi dumpsite,South India

Unscientific disposal of municipal solid waste causes groundwater contamination. The migration of leachate from the solid waste dumpsite to the aquifer varies according to the geohydrological profile of the dumpsite. A detailed study of the mechanism of leachate percolation to the groundwater helps to design a proper groundwater remediation technique. Multilevel boreholes were drilled in the periphery of the Perungudi dumpsite, Chennai, India. The major lithological layers and the geochemical analysis of the contaminant migrated from the dumpsite to the underlying aquifer has been studied. The distribution of heavy metals such as Pb, Fe, Zn, Cr, and Cd follows a similar trend in the pollutant source, groundwater samples around the dumpsite, and at various litho units beneath the dumpsite. The analysis thus helps to find an appropriate groundwater remediation technique to remove the specific contaminant and thereby provide a safe drinking water for the surrounding community.     

Environmental impact and vulnerability of the surface and ground water system from municipal solid waste disposal site: Koshe, Addis Ababa

Geo-environmental assessment and geophysical investigations were carried out over the only functional municipal solid waste disposal site of the city of Addis Ababa, Ethiopia, known locally as Koshe. The accumulated wastes from Koshe have impact on the surrounding human and physical environment since the disposal site was not designed. The study deserves emphasis because the city of Addis Ababa currently obtains a considerable portion of its domestic water supply from a well field developed not much farther from and along a groundwater flow direction in relation to the waste disposal site. It was found out that the leachates from the site contain high concentration of biological oxygen demand, chemical oxygen demand, chloride and sulphate besides high concentration of cobalt, nickel and zinc in the surrounding soils. The geophysical results have mapped weak zones and near-vertical discontinuities that could potentially be conduits for the leachate from the wastes into the deep groundwater system. Further, a zone of potential leachate migration from the landfill was identified from the electrical models; the location of this zone is consistent with the predicted direction of groundwater flow across the site. The results further suggested that the open dump site tends to cause increasing amount of pollution on the surrounding soil, surface and ground waters. Furthermore, it was observed that the Koshe waste disposal site has grown beyond its capacity and the poor management of the open dump landfill has reduced the aesthetic value of the surrounding environments. The need to change/relocate the existing waste disposal site to a more suitable and technologically appropriate site is emphasized.     

Nitrate contamination in a shallow urban aquifer in East Ukraine: evidence from hydrochemical,stable isotopes of nitrate and land use analysis

A combined hydrochemical and stable isotope approach was used to investigate the origin of nitrate in the shallow unconfined groundwater of Kharkiv city, Eastern Ukraine. The contamination was investigated in the context of land use within the catchment area. The observed enrichment of sulfate, chloride and nitrate suggests significant groundwater contamination in the shallow urban aquifer, which is widely used as drinking water source for the urban population. Characteristic nitrate/chloride ratios as well as stable isotope ratios (N and O) of nitrate in the most contaminated springs confirmed that septic waste from leaky sewer systems was the main source of nitrate contamination in the groundwater. Nitrate contamination is linked to the type of land use and sewage treatment regime in the catchment area. It is also modulated by the regional hydrogeology, which determines the susceptibility of a given aquifer toward groundwater pollution. A more quantitative assessment of nitrate sources based on the nitrate isotope analysis alone is rather difficult. However, our study confirms that the combination of hydrochemical tracers, robust land-use analysis and nitrate stable isotope measurements represents a valuable approach to identify the origin of the nitrate contamination.     

淮安市垃圾填埋场地质特征及其防渗评价

正确分析评价垃圾填埋场的地质特征和防渗方案,对垃圾填埋场的选址、设计以及施工运营极为重要。从自然环境、地层结构及岩性特征等方面阐述了淮安市某垃圾填埋场的地质特征,分析了填埋区含水层分布、厚度、赋水性等水文地质条件;结合室内试验和野外试验,综合确定了填埋区岩土层渗透系数大于1×10^-7cm／s,表明填埋区不具备天然防渗的条件,需采用人工防渗系统才能有效的阻滞垃圾渗滤液对周边环境的影响。     

Development of a master plan for industrial solid waste management

Rapid industrial growth in the province of Khuzestan in the south west of Iran has resulted in disposal of about 1750 tons of solid waste per day. Most of these industrial solid wastes including hazardous wastes are disposed without considering environmental issues. This has contributed considerably to the pollution of the environment. This paper introduces a framework in which to develop a master plan for industrial solid waste management. There are usually different criteria for evaluating the existing solid waste pollution loads and how effective the management schemes are. A multiple criteria decision making technique, namely Analytical Hierarchy Process (AHP), is used for ranking the industrial units based on their share in solid waste related environmental pollution and determining the share of each unit in total solid waste pollution load. In this framework, a comprehensive set of direct, indirect, and supporting projects are proposed for solid waste pollution control. The proposed framework is applied for industrial solid waste management in the province of Khuzestan in Iran and a databank including GIS based maps of the study area is also developed. The results have shown that the industries located near the capital city of the province, Ahwaz, produce more than 32 percent of the total solid waste pollution load of the province. Application of the methodology also has shown that it can be effectively used for development of the master plan and management of industrial solid wastes.     

Using Generic and Pesticide DRASTIC GIS-based models for vulnerability assessment of the Quaternary aquifer at Sohag, Egypt

Groundwater resources in the Sohag area, Egypt are currently threatened by contamination from municipal and industrial activities, and agricultural pesticides. To cope with the growing population, there has been development in the desert zone on both sides of the Nile Valley including agricultural investment areas, wastewater disposal sites, new urban areas, and industry. Use of agrochemicals in the old cultivated and newly reclaimed lands and wastewater disposal sites in the study area represent the most hazardous contamination sources. Prevention of contamination and management of the Quaternary aquifer is urgently needed. To address vulnerability assessment of the Quaternary aquifer, the Generic and Pesticide DRASTIC GIS-based models have been used. The Generic DRASTIC index ranged between 94 and 189, and the Pesticide DRASTIC index ranged between 94 and 226. The results showed that 83% of the Quaternary aquifer is characterized by the high and very high vulnerability classes to municipal, industrial and agricultural pesticides contamination. It was found that nearly all the development projects are located in the very high vulnerability class areas. Management alternatives for the Quaternary aquifer may be improved by application of these models, allowing sensitive groundwater sources to be protected for continuing use in the future.     

Application of electrical imaging to leachate plume evolution studies under in-situ and model conditions

Electrical imaging (resistivity tomography) is increasingly used as a geophysical exploration technique in contaminated land research. The present work demonstrates the efficiency of electrical imaging in monitoring pollution plume evolution under both in-situ and model conditions. The in-situ campaign was done at an unlined landfill site situated in the city of Patras, Hellas. A partially saturated zone of alluvial fan deposits underlies the site, which retards leachate percolation to the underlying water table. Electrical imaging provided details of the internal structure of the waste tip, and confirmed the presence of a leachate plume beneath the base of the landfill. This field data component provided the constraints for the design of a generic model of contaminant infiltration into partially saturated sand. The aim was to study leachate plume evolution in a laboratory environment. For this purpose, a miniaturised resistivity tomography technique, developed at Cardiff University, was used to image the resistivity distribution before during and after contaminant infiltration. Comparison of resulting two-dimensional tomography with observed plume geometry at the end of the test showed the miniaturised electrical imaging technique to be highly effective. Experiment showed that contaminant evolution taking place in the model was gravity-driven, with capillary water in the vadose zone being displaced by the denser contaminant solution.     

Magnetic and ground probing radar measurements for soil pollution mapping in the industrial area of Val Basento (Basilicata Region, Southern Italy): a case study

The joint application of electromagnetic techniques for near-surface exploration is a useful tool for soil pollution monitoring and can also contribute towards describing the spatial distribution of pollutants. The results of a geophysical field survey that was carried out for characterizing the heavy metal and waste disposal soil pollution phenomena in the industrial area of Val Basento (Basilicata region, Southern Italy) are presented here. First, topsoil magnetic susceptibility measurements have been carried out for defining the spatial distribution of superficial pollution phenomena in the investigated area. Second, detailed and integrated measurements based on a high-resolution magnetic mapping and ground probing radar (GPR) profiling have been applied to investigate the subsurface in two industrial areas located in more polluted sites that were identified during the first phase. Our monitoring strategy discloses the way to rapidly define the zone characterized by high pollution levels deriving from chemical industries and traffic emissions and to obtain the way information about the presence of local buried sources of contamination.     

Experimental and analytical model studies on leachate volume computation from solid waste

An extensive use of solid-waste landfills for disposal of municipal and industrial wastes have prompted increased attention to groundwater pollution caused by leachate generated in such landfills. The potential for groundwater contamination by leachate has necessitated engineering designs for landfills. The quantity of leachate generated from the solid waste and the movement of water through the solid waste depends on water input and the solid-waste characteristics. This paper dealt with the experimental investigations using the laboratory solid-waste leaching column to estimate the total leachate volume/leachate flow for unsaturated and saturated conditions. The hydraulic properties of the solid waste like initial moisture content, field capacity, permanent wilting point, saturation moisture content, effective void ratio, saturation hydraulic conductivity and saturation suction pressure were determined from the small-scale laboratory experiments, which are the input for analytical model study of leachate flow/total leachate volume for both unsaturated and saturated conditions. The result of analytical model study was compared with the results of experimental investigations. Comparisons of measured and computed total leachate volume/leachate flow using Darcy’s law showed reasonable agreement.     

Application of numerical modeling for groundwater flow and contaminant transport analysis in the basaltic terrain, Bagalkot, India

A three-dimensional steady-state finite difference groundwater flow model is used to quantify the groundwater fluxes and analyze the subsurface hydrodynamics in the basaltic terrain by giving particular emphasis to the well field that supplies domestic, agricultural, and industrial needs. The alluvial aquifer of the Ghatprabha River comprises shallow tertiary sediment deposits underlain by peninsular gneissic complex of Archean age, located in the central–eastern part of the Karnataka in southern India. Integrated hydrochemical, geophysical, and hydrogeological investigations have been helped in the conceptualization of groundwater flow model. Hydrochemical study has revealed that groundwater chemistry mainly controlled by silicate weathering in the study area. Higher concentration of TDS and NO₃-N are observed, due to domestic, agriculture, and local anthropogenic activities are directed into the groundwater, which would have increased the concentration of the ions in the water. Groundwater flow model is calibrated using head observations from 23 wells. The calibrated model is used to forecast groundwater flow pattern, and anthropogenic contamination migration under different scenarios. The result indicates that the groundwater flows regionally towards the south of catchment area and the migration of contamination would be reached in the nearby well field in less than 10 years time. The findings of these studies are of strong relevance to addressing the groundwater pollution due to indiscriminate disposal practices of hazardous waste in areas located within the phreatic aquifer. This study has laid the foundation for developing detailed predictive groundwater model, which can be readily used for groundwater management practices.     

Geoenvironmental site investigation using different techniques in a municipal solid waste disposal site in Brazil

Different geoenvironmental site investigation techniques to assess contamination from a municipal solid waste disposal site in Brazil are presented here. Superficial geophysical investigation (geoelectrical survey), resistivity piezocone penetration tests (RCPTU), soil samples collected with direct-push samplers and water samples collected from monitoring wells were applied in this study. The application of the geoelectrical method was indispensable to identify the presence and flow direction of contamination plumes (leachate) as well as to indicate the most suitable locations for RCPTU tests and soil and water sampling. Chemical analyses of groundwater samples contributed to a better understanding of the flow of the contaminated plume. The piezocone presented some limitations for tropical soils, since the groundwater level is sometimes deeper than the layer which is impenetrable to the cone, and the soil genesis and unsaturated conditions affect soil behavior. The combined interpretation of geoelectrical measurements and soil and water samplings underpinned the interpretation of RCPTU tests. The interpretation of all the test results indicates that the contamination plume has already overreached the landfill’s west-northwest borders. Geoenvironmental laboratory test results suggest that contamination from the solid waste disposal site has been developing gradually, indicating the need for continuous monitoring of the groundwater.     

Optimization of operational parameters for ethanol production from Korean food waste leachate

Recently, research on the production of ethanol from waste has been accelerating for both ecological and economical reasons, primarily for its use as an alternative to petroleum based fuels. In this study, response surface methodology based 2³ -full factorial central composite design was employed to optimize the parameters of ethanol production from Korean food waste leachate. The reducing sugar concentration of the food waste leachate determined by the dinitrosalicylic acid method was 75 g/L. A second order polynomial model was developed to evaluate the quantitative effects of temperature, pH and reducing sugar concentration in order to find an optimum condition for the ethanol production from food waste leachate. From the experimental result, maximum ethanol concentration of 24.17 g/L was obtained at the optimum condition of temperature (38 °C), pH (5.45) and reducing sugar concentration (75 g/L). The experimental value (24.17 g/L) agreed very well with the predicted one (23.66 g/L), indicating the suitability of the model employed and the success of response surface methodology in optimizing the conditions of ethanol production from food waste leachate. Canonical analysis indicated that the stationary point was a saddle point for the ethanol yield. Despite being a waste, an ethanol yield of 0.32 g ethanol/g reducing sugar demonstrated the potential of food waste leachate as a promising biomass resource for the production of ethanol.