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.     

Evaluation of an abandoned aggregate quarry used for uncontrolled waste disposal using remote sensing technologies (Atabey,Isparta-Turkey)

Today, waste is an important environmental problem that needs to be solved. The way it is collected and managed should be considered with respect to the negative impact on the environment. Although the Atabey aggregate quarry was operated with natural sand-gravel until 2 years ago, it was closed due to technological renovation in the crushing-screening unit and uneconomic production. This area was later used by the Atabey Municipality as a waste storage area. Thus, uncontrolled storage occurred at the quarry site. As a result, new, more intensive environmental problems have emerged in the area, such as visual pollution and the pollution of groundwater. This paper evaluates the impact of municipal solid waste disposal in an abandoned quarry site on groundwater, land surface temperature, land surface moisture, and vegetation cover using GIS (Geographic Information Systems) and remote sensing technologies. According to the obtained results, the solid wastes stored in the area caused groundwater pollution, increased surface temperature, and reduced soil moisture.     

Adverse effects of coal mine waste dumps on the environment and their management

Waste dumps generated from mining that exposes sulfur-bearing overburden can be active sources of acid generation with the potential to severely contaminate soils, surface and groundwater, and endanger both local and downstream ecosystems. A waste rock management strategy ensure that disposal of such material is inert or at least stable and contained, and minimizes the surface footprint of the wastes, and explores options for alternate uses. Reclamation of waste dumps is another or parallel alternative to decrease the potential for adverse effects. At the coal mining area of Karmozd in Iran, large volumes of wastes have been produced and disposed of without any specific care for the environment. In this paper, the impacts of waste dumps on the environment were identified and this was followed by a research program to determine the characteristics of the wastes, their acid generation potential, the availability of hazardous contaminants, and a prediction of their environmental impacts on the site. Data was collected from the target site and by comparing several reclamation alternatives using a Multi-Attribute Decision-Making technique, forestry was selected as the post-mining land use for the waste dumps. Preliminary evaluations indicated that Zelkava could be a useful tree species for this region.     

A field-scale long-term study on radionuclide transport through weathered granites at a site in southern China

A regional strategy for safety disposal of low- and intermediate-level radioactive wastes (LILW) has been implemented in China to protect humans and the environment. A joint onsite and laboratory investigation was conducted for a field site in southern China to assess the probability for safe disposal of LILW, which requires the understanding of long-term radionuclide transport behaviors under field conditions. This study presents the field-scale modeling of radionuclide transport through weathered granites for a conservative, a weakly sorbing and a strongly sorbing tracer by incorporating laboratory and field data. The field-scale radionuclide transport model was developed on the basis of a validated long-term groundwater flow model and field-measured dispersion coefficient, as well as laboratory-characterized strontium and cesium distribution coefficients in the weathered granites. The model was then used to perform the long-term transport prediction and risk assessment of radionuclide pollution for both the natural site setting and the graded site setting. Model simulation reveals that the numerical sensitivities of calculated concentrations are tracer dependent and changing with time. The conservative radionuclide is most sensitive to changes in hydraulic conductivity (K) while slightly sensitive to changes in effective porosity (φ), specific yield (μ) and longitudinal dispersion coefficient (D _L), indicating advection is the main transport process of conservative radionuclide. The weakly and strongly sorbing tracers, on the other hand, are most sensitive to changes in the distribution coefficient (K _d) and less sensitive to changes in the rest of model parameters, revealing that sorption is the main process for controlling the transport of sorbing tracers. A conservative radionuclide plume moves at an average velocity of about 54 m/a, which is too fast to be considered as safe disposal under the natural site setting. However, the plume of the conservative radionuclide could be slowed down to a velocity around 5.3 m/a due to the reduction of the hydraulic gradient under the graded site setting. Therefore, the conservative radioactive wastes could be disposed at the mid-eastern part of the site under the graded site setting because the transport path has been prolonged and thus no conservative radionuclides could migrate out of the site in a reasonable timeframe. For the sorbing tracers, however, results of the computed transport distance are 40 and 2 m at 500 years, respectively. Therefore, they can be disposed safely at the site under both natural and graded site settings. This study provides an insight to the field-scale long-term behaviors of radionuclide transport. The integrated modeling method presented in this study is most useful for the environmental impact assessment of the site conditions relevant to the safe disposal of hazardous wastes.     

城市垃圾的地质处置

城市固体废物（城市垃圾）是国际上现代化城市环境污染的主要污染源之一,发达国家非常注重固体废物地质处置的研究,这一领域是环境工程与水资源工作者研究的热点问题。我国城市垃圾对环境的污染非常严重,目前有三分之二的城市已形成“垃圾包围城市”的严重局面。随着经济的发展,我国城市固体废物的数量增长很快。如何处理庞大的城市垃圾将是关系到经济发展、水资源和环境保护的重大问题。本文介绍了我国城市垃圾的现状和目前国际     

浅层地下水氯代烃污染天然衰减速率的估算

天然衰减恢复技术是恢复和控制浅层地下水氯代烃污染的技术之一,如何简便获取可靠的氯代烃衰减速率常数是该技术应用的一个关键。趋势线分析方法是一种简便有效的方法,在污染羽状体稳定的条件下,通过地下水流向上至少3口监测井的资料,能够比较准确地估算出污染物的天然衰减速率常数和生物降解速率常数。某氯代烃污染典型区的应用实例研究表明,该区四氯乙烯(PCE)的天然衰减速率常数和生物降解速率常数分别为0·000925d-1和0·000537d-1,证实该区浅层地下水中的PCE存在天然生物降解,但降解速率比较缓慢。忽略吸附作用的天然衰减容量计算所得出的天然衰减速率常数明显小于实际结果,说明尽管典型区包气带及含水层介质的有机碳含量很少,但它们对PCE的吸附作用不容忽视。     

Comparison of volatile organic compounds in stormwater and groundwater in Seoul metropolitan city,South Korea

Volatile organic compounds (VOCs) detected in stormwater were compared with VOCs present in emission sources, air, groundwater, and influent to sewage treatment plants in Seoul to understand their fate and transport in the urban hydrological system. Stormwater is a carrier of non-point source pollutants and contains VOCs from land surfaces and air. Samples of stormwater and influent to sewage treatment plants were collected and analyzed for 61 VOCs, while the VOCs in emission sources, air and groundwater were investigated through literature reviews for comparison. The results showed that the most frequently detected VOCs in stormwater were similar to those in air. However, the atmospheric concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX), and methyl tertiary-butyl ether (MTBE) were too low to explain their frequent detection and high concentrations in stormwater. As a result, land surfaces seem to be a primary source of these VOCs in stormwater. Comparison of the VOCs in stormwater and groundwater showed that toluene and MTBE were frequently detected in both media, but more often and at higher concentrations in stormwater. This finding indicates that stormwater recharge is a source of toluene and MTBE in groundwater. Regarding groundwater, land surfaces seem to be a primary source of toluene, while urban air is the primary source in the case of MTBE. Specifically, the MTBE values in air were sufficiently high to explain its levels in groundwater, which had continually increased and remained low afterward. Furthermore, the high ratios of TEX (toluene, ethylbenzene, and xylenes) to benzene and MTBE in stormwater indicated that TEX had additional sources other than vehicles, most likely hydrocarbon solvents. These solvents seem to be a primary source of TEX and other frequently detected VOCs in stormwater. However, trichloroethylene (TCE), tetrachloroethylene (PCE) and their dechlorination intermediates were far more frequently detected and at higher concentrations in groundwater than in stormwater. Additionally, their concentrations frequently exceeded the water-quality criteria. It seems that halogenated solvents had produced contamination plumes of these chlorinated VOCs in the Seoul aquifer. Based on VOCs detected in Seoul, stormwater was mixed with groundwater in combined sewers and flowed into sewage treatment plants. The results imply that organic solvents should be handled with extreme care to protect groundwater quality.     

北京砂石坑回填物对地下水水质影响分析

本文介绍了北京砂石坑回填现状,分析了回填物的污染组分特征。以北天堂生活垃圾填埋场和老山建筑垃圾填埋场为例,分析了生活垃圾和建筑垃圾对地下水的影响程度。结合回填物的特点,提出相应的处理对策。针对已造成地下水污染的回填地区,提出科学的污染控制和治理方法。     

在某污染的工业废物填埋场环境水文 地质评价中的同位素水文学研究

本文论述了某污染的工业废物填埋场场址的地质、水文地质条件,应用水化学方法、环境同位素技术(地下水中氚及氢、氧稳定同位素)和同位素单孔示踪技术等同位素水文学领域中的新方法对区内地下水的活动条件以及填埋场场址区分布的第四系孔隙潜水和第三纪红层孔隙-裂隙水的成因进行了分析,测量并确定了填埋场下部地下水的流速及流向。研究结果表明场区地下水的运动与地表水无直接水力联系。污染的工业废物填埋后不会通过地下水的迁移造成对地表水的污染,进而证实填埋场的地质、水文地质条件对处置污染的工业废物是安全可靠的。     

Site investigation on heavy metals contaminated ground in Estarreja — Portugal

Owing to its five decades in the chemical industry, Estarreja is one of the most important industrial areas in Portugal. Intensive industrial activity along with both direct discharge of the effluents into natural water streams and uncontrolled waste disposal on the ground has, throughout the years, had strong impact on health and welfare. Recently an association between industry and local authorities was created — ERASE. The main goal for this association is to find, in co-operation with the Portuguese Environmental Ministry, a cost-effective solution to deal with the soil/sediments contamination and solid waste problem.

The ERASE association planned to build a landfill for both solid waste and contaminated soil/sediments disposal. In order to determine more accurately the volume of material to be disposed of in the landfill, a site investigation was carried out during September/November 1998. The site investigation consisted mainly of systematic soil sampling at shallow depths, both within the industrial area and along the natural water streams.

The site investigation results revealed high concentrations of toxic pollutants, mainly heavy metals (namely As, Hg, Pb and Zn), in the soil of the industrial area. Much higher concentrations were found in the sediments of the water streams, several kilometres away from the industrial complex (the pollution source area).

In most cases, concentration increases with depth, reaching groundwater. Therefore the site investigation programme carried out could not determine the full extent of the contamination. Consequently, further studies were strongly recommended, which should include a wider and deeper investigation area and groundwater sampling.     

Organic Contamination of Soil and Goundwater in the Piedimont Plain of the Taihang Mountains

The risk of groundwater contamination following the infiltration of waste surface water, is of great interest, particularly in areas experiencing water shortage. In this study, the distribution characteristics of contaminants along the Cihe River, in the piedimont plain of the Taihang Mountains, China, was investigated by measuring the soil and water samples. The main organic contaminants detected in different media include hydrocarbons, chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, and pesticides. The main contaminants found in different media are mostly derived from the river water, which can be seen from the results of waste water from the river and groundwater, from the soil samples from different depth and distance of the profiles along the river. The distribution characteristics showed that there has been a natural attenuation of the contaminants from the river during their transportation through the soils and groundwater. The sorption of organic compounds to soil organic matter is thought to be a main mechanism of natural attenuation.     

An environmental geomorphologic approach to site selection for hazardous wastes

Geomorphological features are essential parts of the environment and they represent an important conditioning factor for the development and distribution of certain biological assemblages, as well as for a variety of human activities. However, environmental geomorphology usually receives very limited or no attention at all in the process of environmental impact assessment (EIA). Nevertheless, the site selection process for hazardous wastes in environmental impact studies for individual projects plays an essential role. In order to determine the most suitable site in a region for municipal/hazardous wastes, several criteria are used, including geology, groundwater condition, climate, and land use. The present work describes a methodology taking advantage of environmental geomorphological features, and reducing these criteria in the site selection procedure in land disposal of waste; in addition, a case study is presented to demonstrate the applicability of the proposed methodology. The validity of the adopted site screening method is explained. This methodology comprises the use of a single geomorphological map to locate suitable landfilling sites for hazardous waste, instead of using separate maps for geological features, climatic features (temperature, precipitation, and speed and direction of the prevailing wind), slope and erosion. Furthermore, the present study is compared with a previous study performed in the GAP region, where the use of land resources is crucial for agricultural and water management purposes. The application of the described selection process and the verified method in this region shows that the adopted method and detailed criteria are valid.     

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.     

Case studies in organic contaminant hydrogeology

The effective management of domestic solid waste and hazardous, toxic, and radioactive waste is a major problem in the area of environmental geology and water sciences over the world. This series of case studies of organic contaminants from both solid and hazardous waste disposal facilities provides examples of these problems. The facilities were investigated to determine risks and liabilities before acquisition, to determine the site hydrogeologic conditions for design of appropriate groundwater monitoring plans, and/or to determine the potential for groundwater contamination. The results of these studies and investigations by Waste Management Inc. (WMI) and its consultants have shown certain relationships in the distribution of organic pollutants to the different geologic and hydrogeologic charac teristics of each facility. In each of the case studies, all 129 priority pollutants were analyzed in private wells and/or monitoring wells at the request of regulatory agencies. The 31 volatile organic compounds (VOCs) of the priority pollutant list were the majority of the organic compounds detected and these data are evaluated in each case study. The case studies are on disposal facilities located in glacial tills, carbonaceous weathered clay soils, weathered shale, limestone bedrock, dolomite bedrock, and alluvial and sedimentary deposits. A brief discussion of groundwater quality impacts and remedial measures also is included.Presented at the Second Annual Canadian/American Conference on Hydrogeology: Hazardous Wastes in Ground Water—A Soluble Dilemma. Banff, Alberta, Canada, June 26, 1985.     

Daily and seasonal stem radial activity of Populus euphratica and its association with hydroclimatic factors in the lower reaches of China’s Heihe River basin

The Vado Carranza dump, located in the Mexicali Valley, Baja California, northwest Mexico, was operated for more than 15 years receiving about 30 tons/day of solid wastes. The disposed wastes were periodically burned in open air. The presence of a shallow aquifer in the area makes the groundwater vulnerable to contamination processes. The purpose of this study was the evaluation of heavy metals content (Cu, Cd, Ni, Pb and Zn) in soil and groundwater in the vicinity of this dump. The results indicate high content of metals in soil, mainly at a superficial level, with the highest concentrations in the areas where burning of wastes occurred. Elevated concentrations of cadmium and copper were detected in groundwater with the highest concentrations occurring in monitoring wells located in the north side of the dump, downward of groundwater flow. Although the high content of metals in soil can be attributed to the burning of waste, other sources of pollution could be the agricultural irrigation in the vicinity of the dump. The program PHREEQC was used to model the geochemical evolution of groundwater. Results suggest that evaporation of the contaminated waters circulating below the landfill is one of the key processes that explain the increased concentration of contaminants in groundwater and its seasonal variations. As groundwater flows away from the dump, evaporation can concentrate the chemicals making the water more toxic. These results are important because they illustrate processes that are likely to occur in landfills located in other desert areas of the world.     

Pollution effects of wastewater sludge application to sandy soils with particular reference to the behaviour of mercury

Hammarsdale, an industrial centre about 40 km inland from the coastal city of Durban, South Africa experiences effluent treatment problems typical of highly industrialised centres. The majority of the factories in the area manufacture textiles, with the remainder comprising chemical manufacturers and a large chicken processing plant. Effluent produced by these industries constitutes approximately 97% of the flow to the local wastewater treatment works. This is operated by Umgeni Water, a regional water supply authority which has an interest in pollution control as part of its integrated catchment management strategy. The activated sludge treatment process employed at the works produces a sludge which, following dewatering, is transported to a nearby land disposal site which has been engineered to ensure environmentally acceptable use is made of the site. The heavy metal concentrations of the sludges produced by the Hammarsdale Wastewater Works have long been a matter of concern, in particular the elevated concentrations of Hg. Investigations of the land disposal site showed that the Hg is bound in the upper topsoil (0–10 cm), and only very low concentrations are found in the subsoil. As the soils at the disposal site possess low cation exchange capacities, the difference between Hg concentrations in the top and subsoils may be attributed to binding of the Hg by organic matter introduced by sludge addition. Current research on the disposal area is focused on the movement of Hg, N and other elements through the soil profile into plants, surface and groundwater resources, with the ultimate aim of identifying suitable crops for cultivation at the site following its use as a sludge disposal facility.     

Contaminant migration at two low-level radioactive waste sites in arid western United States – A review

 Contamination of the unsaturated zone and ground water at the Beatty, Nevada and Richland, Washington low-level radioactive waste sites shows that pathways exist for rapid lateral and vertical migration of contaminants through unconsolidated clastic sediments that comprise the 100 m-thick unsaturated zones of those arid disposal sites. Disposal of liquid wastes at the Beatty site until 1975 may have contributed to rapid migration of contaminants, but negligible amounts of liquid wastes reportedly were disposed at the Richland LLRW site and similar problems of contaminant migration exist. Pathways for vertical migration in the unsaturated zone include fractures and, at Richland, clastic dikes; lateral migration pathways likely are facies-controlled. Disturbance of the disposal sites contributed to increased infiltration of the unlined waste trenches after closure; simulations that used Beatty sample data show dramatic increases in recharge with disturbances necessary to develop the site. Because neither an arid climate nor presence of a thick unsaturated zone offer effective barriers to ground-water contamination, reliance on those factors at proposed sites such as Ward Valley, California and elsewhere is unwarranted. Received: 4 February 1998 · Accepted: 4 May 1998     

Investigation of groundwater contamination using electric and electromagnetic methods at an open waste-disposal site: a case study from Isparta, Turkey

 Geophysical methods, when integrated with soil chemical and hydrogeological methods, can be used to investigate groundwater contamination. Direct current (DC) resistivity geo-electrical sounding and very-low-frequency electromagnetic (VLF-EM) data were collected at an open waste site used by the municipality of the city of Isparta, Turkey. The groundwater at shallow depths in alluvium, which is composed of gravel, sand and clay, were expected to be hazardously contaminated under and around the open waste-disposal site, in which both household and industrial wastes are known to be disposed of improperly. In this study, we mapped the spread of groundwater contamination using a VLF-EM method, which allows fast and inexpensive data collection. The method complements the results of geo-electrical sounding. There is a good correlation between the results of the VLF-EM and the DC-resistivity methods employed for the investigation of subsurface structure of the site, where soil chemical and previous hydrogeological surveys have indicated high levels of chemical concentrations. Received: 17 January 2000 · Accepted: 12 August 2000     

极低放废物近地表处置的环境安全评价方法研究

放射性废物处置是当前严峻的环保问题之一,从经济、安全和高效角度出发,将极低放废物从中、低放废物中分离出来单独处置,对核废物的管理与处置具有重要意义。本文以我国西南某极低放废物备选处置场为研究对象,系统分析了处置的相关技术方法,重点研究了屏障技术和环境安全评价方法及其应用。针对拟建在古泥石流体山区山顶上的处置场,选取核素90Sr作为处置对象,选用盆状屏障式处置库,估算产生的核素90Sr的总活度和比活度。选用筛分的颗粒d<1 mm的介质作为屏障材料,厚度为0.5 m,批试验结果显示上述材料对90Sr的吸附效果明显;模拟计算结果显示核素90Sr在50 a内被完全阻滞在包气带中,可以达到安全处置废物的要求。     

An innovative hydrogeologic setting for disposal of low-level radioactive wastes

A natural unique hydrogeological setting favorable for safe and economical disposal of low-level radioactive wastes occurs in the flat hinterland of southeastern North Carolina. The uniqueness results partly from the absence of vertical and horizontal groundwater gradients, representing a nonflow, or null, zone. The null setting is localized to key horizons 30 to 75 feet below land surface and to areas where glauconitic sandy clays of the Peedee Formation lie under less than 25 feet of surficial sandy clays; the Peedee contains nearly stagnant brackish groundwater slightly below the proposed disposal zone.Issues to overcome include: (1) demonstrating better combined safety and economical features over conventional and prescribed settings, (2) dewatering the low-permeability disposal zone for the 20-year operational period, and (3) changing rules to allow disposal slightly below the zone in which the normal water table occurs.Favorable site characteristics of the key setting are: (1) no major aquifer to contaminate, (2) no surface streams or lakes to contaminate, (3) optimal ion exchange and sorptive capacity (clay and glauconite pellets), (4) no appreciable or distinctive vertical and horizontal gradients, (5) no elongated contaminated plume to develop, (6) no surface erosion, (7) a capable setting for injection of potential contaminated water into deep brackish water wells, if needed and allowed, (8) minimum problems of the overfilled bathtub effect, (9) no apparent long-term harmful environmental impact (normal water table would be restored after the 20-year period), (10) relatively inexpensive disposal (engineered barriers not needed and desired), (11) simple and relatively inexpensive monitoring, (12) large tracts of land likely available, and (13) sparse population.In spite of legal and political obstacles to shallow land burial, the null setting described is a capable hydrogeological host to contain low-level radioactive wastes. The setting may have safety and economic advantages over selected sites in eastern North America and over innovative technological experiences in Europe.