Case study: a 3D resistivity and induced polarization imaging from downstream a waste disposal site in Brazil

A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence (ρ < 20 Ωm), water table depth, and groundwater flow direction. A conductive anomaly (ρ < 20 Ωm) outside wastes placement was interpreted as a contamination plume. Chargeability model was also able to imaging waste presence (m > 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone (m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/ρ) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment.     

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.     

高放废物处置库甘肃北山预选区地下水的形成

在高放废物处置库场地选择和性能评价中,水文地质特征是最重要的因素之一,地下水的形成则是水文地质研究中的首要问题。在水文地质、地下水化学、同位素、CFC、地下水动态等资料综合分析的基础上,探讨了高放废物处置库甘肃北山预选区地下水的形成问题。研究结果表明,北山地区地下水以赋存于变质岩、岩浆岩、碎屑岩、碳酸岩节理、裂隙中的基岩裂隙潜水为主,地下水化学成分具有明显的水平分带性特征,地下水动态类型主要为入渗—蒸发—径流型,结合地下水同位素和CFC 特征,认为区内地下水主要由当地大气降水入渗补给形成。浅部地下水主要由现代区内降水补给形成,而深部地下水则可能由地质历史时期降水补给形成。     

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.     

Environmental geological assessment of a solid waste disposal site: a case study in Sivas, Turkey

The selection of the disposal site is probably the most important step in the development of solid waste management. In site selection, geology plays a determining role. This study evaluates the characteristics of the environment on the basis of the geological, hydrogeological and geo-engineering properties of the solid waste site of the Sivas city, Turkey. The area is underlain by the Oligocene-Miocene rocks which have limited aquifer properties. Thin Quaternary alluvium and soil cover overlie the Oligo-Miocene rocks, which are represented as well graded sand and inorganic silt of low plasticity. The Quaternary alluvium and soil cover are classified as inorganic clays having a low plasticity and the permeability varies from 1.2×10⁻⁶ to 3.11×10⁻⁶ m/s. These values are much higher than 1×10⁻⁸ m/s, which is accepted for waste disposal standards. Seepage waters have a potential to pollute the ground water and the Kızılırmak River, which is 500 m to the southwest of the waste disposal area and because the disposal site is close to the river, the potential for flash flooding poses a high pollution risk. The waste disposal area must be covered by clay layers or an impervious artificial membrane. In addition, seepage must be controlled and removed from the site.     

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.     

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.      

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.     

Landfill site selection based on reliability concepts using the DRASTIC method and AHP integrated with GIS – a case study of Bengaluru city,India

The selection of landfill sites for municipal solid waste (MSW) disposal involves consideration of geological, hydrological and environmental parameters which exhibit large spatial variability. Therefore, it is necessary to define, to what extent the chosen sites are reliable such that the probability of environmental pollution and health risks to population is minimal. In the present study, groundwater vulnerability to contamination has been assessed using the standard DRASTIC method. The results showed that the study region has 9.45% of very less, 32.94% of less, 25.47% of moderate, 22.79% of high and 9.35% of very high vulnerable zones. The study also revealed that none of the landfills are located in safe zones. This suggests that it requires proper remedial measures to avoid environmental pollution. A landfill site selection process has been carried out using the Analytical Hierarchy Process integrated with Geographical Information System tools. The obtained results showed that only 3.59?km² (0.08%) of the total area is suitable for landfills. The reliability analysis of the site suitability revealed that landfills are located at unreliable locations where the probability of risk to environmental pollution is high. The presented approach assists decision-makers in selecting reliable locations for the safe disposal of MSW.     

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.     

Deterioration of groundwater quality in the vicinity of an active open-tipping site in West Malaysia

There is an urgent need for characterization of leachate arising from waste disposal to ensure a corresponding effective leachate management policy. Field and laboratory studies have been carried out to investigate the impact of municipal landfill leachate on the underlying groundwater at a site in West Malaysia. The solid waste was disposed of directly onto an unprotected natural soil formation. This situation was made worse by the shallow water table. The hydrochemical composition of groundwater in the vicinity of the site (background) is a dilute mixed cation, bicarbonate water. The high ionic balance error of ~13.5% reveals that the groundwater body underneath the site was a highly contaminated leachate rather than contaminated groundwater. Elevated concentration of chloride (355.48 mg/L), nitrate (10.40 mg/L as NO₃), nitrite (14.59 mg/L), ammoniacal-N (11.61 mg/L), sodium (227.56 mg/L), iron (0.97 mg/L), and lead (0.32 mg/L) measured downgradient indicate that the contamination plume has migrated further away from the site. In most cases, the concentration of these contamination indicators, together with the ranges of sodium percentage (66.3–89.9%) and sodium adsorption ratio (10.1–19.7%), were found to be considerably higher than the limit values of safe water for both domestic and irrigation purposes, respectively.     

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.     

Hydrogeochemical Evaluation of Heavy Metal Loadings to Waters and Sediments by Leachate: A Case Study from the Golbasi Waste Disposal Site,Ankara, Turkey

At sites of groundwater contamination, predictions of contaminant behavior and evaluation of remedial strategies depend on identification and characterization of the geochemical processes affecting contaminant migration. Heavy-metal loadings to waters and sediments by leachate from the Golbasi waste disposal site in Ankara, Turkey, have been evaluated quantitatively using hydrogeochemical modeling. The groundwater of the waste disposal area, characterized by high concentrations of Ca, K, Cl, Cd, Pb, Zn, Cu, B, Ni, SO₄, and NO₃, contaminates the waters and sediments in the down-gradient area, Eymir Lake and a swamp along the flow path. An advective mass transport duration is ～15 years for unretarded contaminants to move from the waste disposal well area to the southern shoreline of Eymir Lake. Mixing calculations suggest that the down-gradient groundwater is formed by mixing of 40 to 72% upgradient groundwater and 28 to 60% waste-disposal-area groundwater, as well as Eymir Lake surface-water ion concentrations formed by mixing of down-gradient groundwater (3%-25%) and swamp-water ion concentrations (75-97%) along the flow path. An evaluation of the changes in concentration of trace ion-related precipitation/dissolution and exchange reactions between water and sediments for the formation of both Eymir Lake surface-water composition and the down-gradient groundwater composition indicate considerable trace-ion content of the clays (exchangers) and related reactions in the system. These results suggest that the amounts of contaminants removed from or added both to the down-gradient groundwater and to surface waters through mixing, dilution, and evaporation processes are rather small. The amounts of ions in the waters at the present stage of the contamination process are predominantly governed by exchange and dissolution/precipitation reactions.     

Integrated use of hydrochemistry and resistivity methods in groundwater contamination caused by a recently closed solid waste site

 In order to investigate the groundwater contamination by solid waste disposal using both hydrochemical and geophysical methods, the Halkalı (I˙stanbul) solid waste disposal site which was closed in 1994 was investigated. The disposal site lies on a ridge between two valleys filled with alluvium. A total of six boreholes were drilled on two lines across the Menekşe valley adjacent to the Halkalı site. Groundwater samples collected from these boreholes were analyzed for various contaminant parameters. The results indicate that TDS and chloride concentrations decrease horizontally away from the waste site whereas they increase with depth. Electrical soundings carried out at 12 locations yielded high resistivity values at the upstream part of Menekşe valley while lower values were obtained from the locations near the leachate seepage points. Received: 11 November 1997 · Accepted: 23 February 1998     

Assessment of groundwater contamination from a hazardous dump site in Ranipet, Tamil Nadu, India

Tanneries located in an industrial development area of Ranipet (India) manufactured chromate chemicals during 1976?C1996. A large quantity of associated hazardous solid wastes has been stacked about 5-m high above ground level, spread over 3.5?ha inside one of the factory premises. The study area receives an average annual rainfall of 1,100?mm. The granitic formation in the northern part of Palar River catchment has high infiltration rates and has resulted in fast migration of the contamination to the water table. Chromium levels in the groundwater were found up to 275?mg/l. The available hydrogeological, geophysical and groundwater quality data bases have been used to construct a groundwater flow and mass transport model for assessing the groundwater contamination and it has been calibrated for the next 30?years. The migration has been found to be very slow, with a groundwater velocity of 10?m/year. This is the first field-scale study of its kind in this industrial area. The findings are of relevance to addressing the groundwater pollution due to indiscriminate disposal practices of hazardous waste in areas located on the phreatic aquifer. Further, it has been reported that the untreated effluent discharge adjacent to the chromium dump site is most influential in the migration of contaminants.     

Engineering geological evaluation of geological barrier rocks at landfills and repositories

 A site specific evaluation of geological barriers is required for landfills and waste repositories. The waste-repository-rock system has to be taken into consideration for this. Since the geotechnical barrier in conjunction with geological barriers contributes considerably to long-term isolation of the harmful substances from the biosphere, it is absolutely necessary to use engineering geology and hydrogeological methods for a quantitative assessment of the barrier effect of the host rock and the geological environment. For a waste disposal mine, the load-bearing capacity of the rock, the protective properties of the surrounding rock formations and the geological stability of the area are important factors in a safety analysis, of which the geotechnical stability analysis is an important part. Such an analysis comprises an engineering geological study of the site, laboratory and in situ experiments and model calculations, long-term monitoring, and special geological and geochemical investigations. Existing geomechanical modelling techniques provide a useful tool to perform barrier integrity calculations and to design an underground disposal mine. As an example, the barrier performance of the rock salt of the Gorleben salt dome is demonstrated using various safety indicators. Received: 3 January 1997 · Accepted: 29 January 1997     

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.     

高放废物处置库预选场地水文地球化学模拟

阐明了研究区水地质条件及地下水化学特征；通过水地球化学计算，研究了地下水与固相间的反应趋势；模拟了地下水垂向流动过程中发生的水岩作用；进而从水地球化学角度对预选场地高放废物地质处置的适宜性作出初步评价。     

Impact of liquid waste disposal on potable groundwater resources near Perth,Western Australia

 Drilling of 15 boreholes at a disused liquid waste disposal site near Perth, Western Australia, has indicated that a contamination plume extends about 1000 m in a southerly direction from the site in the direction of groundwater flow. The plume is up to 600 m wide and 5–40 m thick. Chemical and microbiological analyses have indicated that contaminated groundwater contains high concentrations of ammonia, iron, and bacteria at levels that commonly exceed national drinking water guidelines. It is likely that a proposed water supply production well in the path of the contamination plume will have to be abandoned, and additional wells may have to be abandoned if the plume continues to extend in the direction of groundwater flow. There is currently insufficient information to indicate whether the plume is continuing to expand, but studies on similar plumes in the Perth metropolitan area have indicated that contaminated groundwater can move at rates up to 100 m yr^–1. Several other liquid waste disposal sites are now located in residential areas of Perth where wells are used for garden irrigation. Further work is required to ensure that there is no potential impact of groundwater contamination on public health in these areas. Received: 31 July 1995 · Accepted: 18 September 1995     

阿拉善塔木素地段地下水补给来源与演化特征分析

内蒙古阿拉善塔木素地区是我国高放废物地质处置预选地段之一,开展相应的水文地质特性评价研究对于科学评估其适宜性尤为重要,而充分认识地下水的补给来源与演化过程是了解地下水的形成机制与更新能力的基础。结合塔木素地区水文地质条件,利用水化学与同位素技术对研究区26组水样进行分析,结果显示:研究区地下水氢氧同位素与西北地区大气降水氢氧特征类似,表明区内地下水主要受到当地大气降水补给,这也与水文地质条件认识相符;区内地下水呈现高矿化度特征,TDS均值达到了2.9 g · L-1,地下水化学类型为Na+-Cl-型,表现出干旱区地下水的典型特征;此外,地下水的氯碱指数均大于0,且Mg2++Ca2+-HCO₃--SO₄2-与Na++K+-Cl-呈线性关系且斜率接近-1,说明了阳离子交换反应普遍发生在地下水化学演化过程中。塔木素重点地段地下水属于不适宜利用的高矿化度地下水,且深部地下水年龄大于5000年,循环交替能力较差。这一认识为该地段处置库选址和场址评价提供了重要的水文地质依据。