- Home
- Conferences
- Conference Proceedings
- Conferences
4th EEGS Meeting
- Conference date: 14 Sep 1998 - 17 Sep 1998
- Location: Barcelona , Spain
- ISBN: 978-94-6282-127-9
- Published: 14 September 1998
1 - 50 of 236 results
-
-
Spectral characteristics at a former industrial site using complex resistivity
Authors A. Binley, A. Eriksen, J. Gascoyne, T. Nguyen and A. KemnaThere is growing interest in using geophysical techniques for characterising former industrial, or 'brown field', sites. In particular, Olhoeft (1996) and others have prompted a number of studies into the use of speetral geo-electrical properties for assessing levels of contamination in sites polluted by hydrocarbons. We report here on the results of a recent survey using complex resistivity to assess the value of resistivity spectra in improving our understanding of the subsurface properties at a former industrial site and the extent of hydrocarbon contamination at the site.
-
-
-
A new method and instrumentation for the soil contamination survey
More LessThe new introduced method for the soil contamination survey is based on the analysis of the soil gas or vapour. This newly developed method offers fast andreliable location of contaminant sourees and trajectories of the contaminant spread. Gas from the pore space in soil and rock formations is commonly known as soil vapour. The composition of this phase, in particular the présence and concentration of organic compounds, reveals vital information about pollution of the subsurface environment. Organic compounds constitute a group of contaminants which impact severely on groundwater resources. The presence and distribution of such pollutants can be detected by a new established technique known as a Soil Vapour Analysis ("SVA") or Soil Vapour Survey ("SVS").
-
-
-
Using subsurface geophysics to avoid environmental degradation while enhancing oil recovery from a producing field
Authors A. Bouvier and T. TantawyThe Tengiz oil field in KAZAKHSTAN, located on the northern and eastern shores of the Caspian Sea, is a major oil field where Russia initiated production more than 25 years ago. In the past three years, Tengiz Chevron Oil (TCO) increased production significantly and was recently considering drilling new holes to boost output. To help to the selection of drilling locations, a 3D seismic survey using both vibrators and dynamite was conducted on the 400 km2 producing field. Because the location accuracy of the current buried pipe network is not sufficiently precise on available maps, a reconnaissance test took place at specific sites where old and recent pipes are known to exist. Most of these sites were also selected for their proximity to sensitive structures : plan facilities, manifold, dike edging the sea and office buildings where safety distances from seismic sources had to be determinated with a view to a forthcoming 3D seismic reflection survey.
-
-
-
Air pollution mapping by portable sensors and DGPS positioning
Authors M. Fernetti, M. Gasparini, G. Manzoni and A. PurgaIn 1994 we applied the satellite positioning method to environmental monitoring (Camus et al., 1994, Cefalo P.,1996). A Carbon Monoxide electrochemical sensor was mounted on a car together with a GPS positioning sensor. The car was driven along the streets of Trieste center and the concentration of this gas was measured every two seconds. By properly choosing the urban route with crossing streets, the data were processed in the form of contour levels, so allowing a mapping of the CO concentration. The data were also processed as street pollution profil es. The sensor has a delayed response of about 9 seconds. Moreover, the CO concentration as measured outside a vehicle suffers a lot of transient peaks due to the exhaustion of any car or motorbyke close to the sensor. Nevertheless immediatly repeated passages on the same street displayed the same concentration within 20%, which is quite a significant result if the measurement campaign is devoted to alert authorities and people of the dangerous pollution.
-
-
-
Magnetic mapping of soil pollution around a glass factory of Bratislava, Slovak Republic
By O. DurzaHeavy metals are important in several ways: many are used industrially in technologically advanced countries, some are physiologically essential for plants and animals - and thus have a direct bearing on human health and agricultural productivity - and many are significant as pollutants of ecosystem throughout the world. Heavy metals in soils have received increasig attention in recent years. Metals, which accumulate in the human body, such as Cd, Hg and Pb, are particular cause for concern. There have been reports of deaths and illness related to environmental Cd and Hg poisoning, and elevated levels of Pb in the blood of infants are becoming more common. These findings have provided a stimulus for more comprehensive studies of known or suspected areas of pollution and for complementary investigations of the chemical behavior of heavy metals in soils. A current method of a lithogeochemical mapping has supposed sampling of a definite soil horizon and following chemical analysis of the elements. Recent studies have shown that under certain conditions magnetic susceptibility can be used as a proxy parameter for the detection of higher heavy metals contents in soils. There were verified in many papers ( Durza et al 1993, 1996; Strzyszcz, Magiera 1996, Versteeg 1996; Kapièka 1997; Hoffman 1997; ...) that detected higher values of magnetic susceptibility of soils' samples above background indicate higher concentration of heavy metals in soil. There were recommended by Mikajev and Zogolev (1990) to use soil kappa-metry like a preliminary method that enable to border zones .Increased geochemical activity", to bring down a bulk of works and to change flexibly the method of mapping.
-
-
-
Mapping of complex hydrocarbons contaminant using geoelectric and electromagnetic methods
Authors A. Godio and G. MorelliA combined geophysical survey was carried out in a oil refinery to study the complex hydrocarbon contamination of the soil and the near surf ace aquifer, resulting from several years of leakage of hydrocarbon products. A near surf ace level characterized by a strong reflector was weIl detected using Ground Penetrating Radar; lateral changes of the strength of the reflection and the subsequent drilling confirmed the existence of a free phase of hydrocarbon in the vadose zone above the water tabIe. Because of the limited thickness of the layer embedded with the residual oil, the geoelectrical resistivity measurements were not effective for detecting this level. The resistivity measurements pointed out very low values in the upper zone of the aquifer; this effect can be associated to complex chemical reactions between the dissolved hydrocarbon phase and the aquifer system. These effects were investigated using high resolution geoelectrical tomography. Soil data resulting from several boreholes confirmed the reliability of the geophysical response. Geochemical and physical analysis of the soil and groundwater samples, combined with the geophysical investigation, allowed the definition of a reliable model ofthe polluted area.
-
-
-
Combined geophysical monitoring of a controlled LNAPL-Release
Authors M. Gruhne, F. Borner, R. Giese, Th. Richter and U. PippigThe exploration of contaminated sites represents a demanding task. Geophysical methods are predestined to deliver a high resolved spatial distribution of underground parameters. A promising strategy is to combine several geophysical methods. The development of qualified equipment and interpretation techniques should take place under undisturbed conditions. A large scale hydraulic experiment was carried out in February 1998 at VEGAS-facility (Versuchseinrichtung zur Grundwasser- und Altlastensanierung) at University of Stuttgart. One main part of the research doing there at VEGAS consists in the investigation of movement and spreading of non-aqueous phase liquids (NAPL' s) in the vadose zone. The objective was to monitor a hydraulic experiment using geophysical methods (complex conductivity tomography and cross-borehole radar tomography) and nongeophysical procedures (TDR, fluid level measurements, fluid pressure measurement).
-
-
-
Geophysical characterization of groundwater protective layers
More LessTo enable an effectice proteetion of near surface groundwater reservoirs against pollution from agriculture, industry or waste disposals the protective qualities of the unsaturated layers on top of the aquifer must be quantified. On that basis the risk of groundwater contamination can be mapped and endangered regions can be protected be governmental regulations. A mean for the protective qualities can be the percolation time from the surface to the groundwater saturated zone. While groundwater is moving through the unsaturated layer the concentration of contaminants is reduced by biological and chemical processes. These processes are time consuming, and as a rule of thumb a percolation time of at least 10 years can offer an effective proteetion of our groundwater resources.
-
-
-
Laboratory investigations to prove low concentrations of hydrocarbons in soils
Authors N. Klitzsch, F. StalImaeh and F. JacobsThe most ecological way to clean soils from organic contaminants is biological remediation. In addition to chemical analyses, geophysical measurements are an useful instrument to monitor the remediation process. Geophysical measurements can provide information of three-dimensional distributions for several parameters, e.g. temperature and resistivity (related to salt and moisture content), which are interesting for the remediation process. In a project supported by the Centre for Environmental Research Leipzig - Halle the possibilities to detect low concentrations of hydrocarbons in soils with geophysical measurements are investigated. The laboratory study is focussed on the speetral induced polarization (SIP) method. Additionally, nuclear magnetic resonance (NMR) measurements are carried out in order to understand petrophysical processes influencing electrical spectra.
-
-
-
Frequency and DC electrical Behaviour of polluted sediments in industrial areas: field and laboratory investigations
More LessThe aim of this research is to find the class and the quantity of pollutants in soils and rocks on the bases of the different electrical behaviour of organic compounds and metallic ions at the solid-liquid interface, as function of electrical frequency in the DC-.;-.200kHzrange. This research started from previous laboratory studies of the polluted sample electrical responses. The electrical behaviour of these samples has been analysed following the method of Losito et al.(1985) pointed out to investigate the phyllosilicate electrical properties. The method starts from the waveform analysis of the electrical signals, that are strongly distorted by the double-layers of clay minerals. The classical THD% (% Total Harmonie Distortion) and the HD%(co) parameters, used in this analysis, are also strictly dependent of the pollutant molecular size and give an "electrical signature" ofthe pollutant-mineral interaction. On the base of the said laboratory results, a Geoelectrical Integrated Method (GIM) has been performed and tested to investigate and monitor the presence of chemical and organic pollutants near riverbed, water tables, and urban waste deposits.
-
-
-
Geophysical studies for geoecological monitoring in Belarus
Authors I. A. Busel, V. V. Kazaryan and V. G. LobodenkoIn spite of their informative value, geophysical methods have not always being used in full measure at geological prospecting and monitoring. Let' s consider, as an example, the case history of point pollution of geological medium from oil boreholes drilling products.
-
-
-
Complex investigation of radon concentrations in soil gas and electrical tomography in Lithuanian Karst Region
Authors D. Michelevicius and R. SeckusThe national radon survey in Lithuania started in 1995. Measurements have been performed in 400 randomly selected detached houses. Two separate used by inhabitants rooms used to be selected for measurements. E-PERM electrets by Rad Elec Inc were used for registration of indoor radon concentrations. The measurements were performed during heating season for 3 or more weeks. The results indicate dependenee of indoor radon concentrations on location of house. Five regions have been detected with average indoor radon concentrations exceeding the national level (55 Bq m") by almost two times. Houses with indoor radon concentrations higher than internationally recommended and nationally adopted levels of action (400 Bq m-3 for existing and 200 Bq m-3 for new houses) have been detected during the survey. One more region with elevated indoor radon concentrations has been identified in the karstic area near Birzai. For identification of this region the data available in the Lithuanian Geological Survey have been used because the measurements in randomly selected houses have been unable to disclose uniquity of this region. Analysis of results shows with small exceptions that the main souree of indoor radon in Lithuania is soiI. Since it is necessary to create the system of radon risk mapping selective measurements of radon concentrations in the soil air have been performed. Electrical tomography measurements were also included in order to get a possible correlation between distribution of radon concentration in soil gas and apparent resistivity anomalies of subsurface.
-
-
-
Detection of anti-personnel landmines (APL) by integration of TEM-resistivity and IR surface temperature data
By C. OelsnerEvery year some 20.000 civilians are killed by landmines (UN estimates). Even if at the Ottawa Conference a convention against anti-personell landmines (APL) was signed, the old problem of mined areas remains still existent. Due to the Ottawa Convention there are following tasks among others: - mined are as must be identified, marked, and feneed as soon as possible, - all mines in these mined areas must be destroyed within 10 years. These problems up to now merely have been solved by deminers with different fully developed magnetic anomaly detection systems. Before the Ottawa Convention, mine producing industries have advertised their products under the aspects of "difficult or even impossible -detectability by conventional demining processes due to minimum iron content of the mines. Therefore the new task, which geophysics has to solve is as follows: detection of a very low conductive target in a very shallow depth from 5 cm to 20 cm. Additional disadvantage are the small sizes of the mines, which go down to diameters of approximately 5 cm. It is evident, that the methods being used must belong to those of remote sensing. In contrast to other geophysical targets a false result of measurement and interpretation will have catastrophic consequences. By UN a detection security of 99% is required. Additional demand is to reduce the rate of false alarm. From geophysical point of view this problem reminds of' 'squaring the circle
-
-
-
LNAPL Detection using ground penetrating radar
By L. OrlandoHere are reported the results obtained from the application of the georadar method for the detection ofLNAPL (Light Non-Aqueous Phase Liquids) when they are floating on the water table. In order to do this study it was necessary to fust consider the georadar response on a theoretical model, which would respond in the closest possible manner to the actual case, and then move on to the field data. The studies on the theoretical model and on the field data have shown that it is not possible to individuate the presence of light hydrocarbons floating on the water table without resorting to the evaluation of attributes. Among the numerous attributes, in this work, only the instantaneous amplitude, phase and frequency were taken into consideration. Among these attributes, the instantaneous amplitude and frequency allow detection of hydrocarbons, while the instantaneous phase gives only a better lateral continuity of reflectors.
-
-
-
The ground soiling by petroleum and other organic liquids: detection and study by GPR and seismic
Authors M. B. Rapoport and V. I. RyjkovOne of the main kinds of environmental pollution is the pollution of the ground with petroleum and other organic fluids, incJuding chemical wastes. Emission from oil wells, breakage of pipelines, leakages from huge reservoirs at the refineries, chemical plants, military bases, filling stations, airports etc- at first should belocalized and observed. Among geophysical methods to be used for studying such pollutions preferenee is given by us to impulse wave methods-GPR [1] and seismic. Although there are principal differences in the character of waves, both methods allow to make the zones of pollution contrast enough at the images obtained.
-
-
-
Detection of hydrocarbon contaminated soil with radiomagnetotellurics
More LessSoH contamination caused by hydrocarbons is a problem for the reorganisation of closed factories and tank farms. It is necessary to determine the kind and content of the contaminants. Soil samples lead to reliable results but the detailed investigation of an area requires a large number of boreholes, which are usually quite expensive. Radiomagnetotellurics (RMT) is comparable to the known VLF-R method but uses a broader frequency range (10-240 kHz). Electromagnetic sounding is possible by using several radio transmitters with different frequencies. The horizontal electric field in the direction of the radio transmitter and the horizontal magnetic field perpendicular to this direction are observed. From the ratio of the amplitudes of these fields the apparent resistivity is derived. The phase between the two fields yields the second measured value.
-
-
-
DC resistivity and time-domain induced polarization survey for the study of ground-water contamination in Bahia, Brazil
Authors A. Rühlow, B. Tezkan and O. A. L. de LimaDC Resistivity measurements were used to identify residual contaminant accumulation in sandstone aquifers by means of conductive anomalies. The contaminated regions were distinguished from conductive lens es of clay by simultaneously coIlected lP data, what would not have been possible by use of the method of DC resistivity alone.
-
-
-
Construction of a 3D hydrogeological model using 2D resistivity imaging to determine potential contaminant pathways
Authors A. C. Vickery and B. A. HobbsThe City of Edinburgh Council is currently redeveloping the West Granton area in north Edinburgh, Scotland. The area has accommodated heavy industrial use for the past 150 years and consequently has numerous possible contaminant sources. A major concern for potential groundwater pollution is the emergence of contaminants on the neighbouring foreshore. This paper concentrates on the sites of two former oil distribution terminals that have been acquired for remediation and redevelopment. Figure 1 locates the old installations used for the storage of various hydrocarbons. By 1987, all the storage tanks and surface structures were dismantled to ground level. Contaminated made ground was cleared from the eastern most site which was awarded a certificate of remediation.
-
-
-
Can resistivity methods be used to locate heave metal contaminated soils?
Authors C. Bernstone and T. DahlinThere are a large number of contaminated sites in Sweden requmng some form of remediation. In many cases the contaminants are heavy metals; here the level of contamination is often unknown. A typical investigation scheme includes chemical sampling to map the extension of the contaminant at the specific sites. Benefits could be derived from the use of additional methods, such as geophysics, to achieve a means of interpolating the result from the chemical sampling scheme. This is rather straightforward for some types of contaminants, e.g., brines that are highly conductive. An essential demand is, however, that there be a large enough contrast between composition of the natural geological environment and that of the contaminated area. In the case of high concentrations of heavy metals, a detectable physical anomaly can be expected, at least in theory. However, heavy metals are easily adsorbed into clays and organic soils. lts detection probably relies on the ohmic conductance, which can contribute to the current paths (i.e., not only electrolytic conductance) .
-
-
-
Unconventional geoelectrical methods to observe the diffusion processes of contaminants in porous media
Authors V. Copertinn, V. Cuomo, G. di Bello, V. Lapenna, S. Piscitelli, V. Telesca and S. TroisiA geophysical survey, based on unconventional geoelectrical prospecting methods, was carried out in a controlled test site located in Montalto Uffugo (CS), Southem Italy. The main objective of the study is to outline the complex geological features of subsurface and to gain information about the hydrogeological features of the investigated area. Subsequently, the geoelectrical measurements will be used to control the time evolution and spatial distribution of contaminants and to analyze the correlation between the soil resistivity and the hydraulic characteristics of aquifer.
-
-
-
Application of geophysical methods for studies of sites, polluted with old war ammunition
Authors D. Kolarov, W. Spyra and H. PetzoldOn the most part of Brandenburgland during the Second World war some battle collisions passed. As the result on battle fields a lot of different ammunitionfrom shellsplintersof grenades and mines up to non burst airbombshave remained.On the other hand Brandenburg land develops widely coal industry. As is known in south part of Brandenburgland there are some open mines for coal production.The presence of huge amountof ammunition'srests convertsa developmentof new coal deposits to very difficult anddangerousbusiness.
-
-
-
Environmental mapping using airborne geophysics in Finland
Authors J. Lerssi, T. Jokinen, J. Lohva and R. PuranenGeological Survey of Finland (GSF) has carried out systematic airborne geophysical surveys in Finland since 1951. The second program started in 1972 using a flight altitude of 30-40 meters and line spacing of 200( 100) meters (Lohva et al, 1996; Peltoniemi, 1986). Today 80 % of the country has been measured. The measurements have been made with fixed-wing aircraft. The differential GPS is utilised in navigation. In lowaltitude measurements the following systems are in use: magnetic, gamma radiation and EM. Total magnetic field is measured with a wingtip gradiometer. The horizontal spacing between the magnetic gradiometer sensors is 21 meters. Earth's gamma radiation is measured with a spectrometer which utilises a 41 litres NAI crystal detector. The electromagnetic unit is dual frequency vertical coplanar coil equipment (Poikonen et al, 1998). The frequencies are 3.1 kHz and 14.4 kHz and coil separation is 21.4 m. The survey results are used in mineral exploration and geological mapping, recently also increasingly in environmental applications. GSF has recently conducted aerogeophysical studies of some contaminated are as in Finland (Lerssi et al, 1997). Ämmässuo is a modern, municipallandfill of Helsinki. Landfill area has been mapped three times, first in the national airborne mapping program (1984) before the operation of the landfill started. The 1993 and 1997 monitoring surveys were carried out in the same north-south flight direction as in 1984 but using tighter (100 meters) line spacing. Magnetic anomalies indicate metallic waste and metal constructions. Comparison of 1984, 1993 and 1997 EM maps of Ämmässuo indicate small changes, which have been estimated guantitatively by layer model and 3-D model interpretation. By total radiation map, it was possible to estimate changes of moisture and soil thickness. Lievestuore pulp millled its waste effluent during 1935-1967 to the nearby Koivusensuo mire, where the Lipeälampi waste pond was formed. GSF carried out airborne measurements and ground surveys around the waste pond. The electric conductivity of the efflucent (mainly sodium lignosulfonate) is high and its spreding into the soils can thus be deciphered by electric methods. The AEM anomalies indicate that the most heavily polluted mire area extends north- and southwards from the pond, which was verified by ground conductivity logging (Puranen et al. 1997). Logging and seismie results were also used as a reference material in interpretation and modelling of effluent plume migration.
-
-
-
Time domain induced polarisation experiments on gasoline contaminated samples
Authors E. Martinho and F. AlmeidaRecently environmental studies have used geophysical methods to delineate oil contaminated sites (Vanhala, 1997). Organic liquids have a high resistivity and thus induction methods are not weil adapted to fine contaminated areas. On the other hand Induction Polarisation has been widely recognised as a useful method for the detecting organic electrical response In field ( Vanhala et al, 1992) and in laboratory (Vanhala et Soininen. 1995) experiments. The later author had a frequency domain approach (SIP) to the problem. On the other hand our initial work carried out in the time domain (Sumner, 1976) and is still in a laboratory phase. In order to study the induced polarisation effect in gasoline contaminated soil samples a GPIB controlled system was developed to carry out electrical measurements as it is shown in Fig.l. This System is able 10 obtain measurements at a rate of ten samples per second. Specially developed porous ceramic electrodes were built to obtain suitable electrical current contacts. Non polarizable electrodes SilverlSilver Chloride were used to measure potential.
-
-
-
Analysis of ground penetrating measurements of a tar lake
Authors B. Forkman and C. SeegraefIn this paper we combine two relatively new methods to analyse a tar lake. The ground penetrating radar measurement has become a quite important method for the analysis of near-surface conditions. The method is based on the spreading of highfrequency electromagnetic waves and on the validation of Maxwell equations. The wavelet-transform (WT) is used for the analysis of measured data. This transform can be used for the time frequency analysis, for the filtering of data and for the detection of the interference of different signal parts. The WT depends on different functions, the socalled wavetet functions, which have different properties.
-
-
-
Testfield for studies of sites polluted with old war ammunition with geophysical methods
Authors I. Wolfgang Spyra, S. Reinhardt, H. Petzold and D. KolarovOn most parts of Federal State Brandenburg battle collisions took place during the Second World War. As the result, a lot of different ammunition from shell-splinters of grenades and mines up to non burst airbombs have remained on battle fields. On the other hand. Brandenburg develops widely coal industry. As is known, there are open mines for brown-coal production in the southern part of Brandenburg. The presence of a huge amount of ammunition's rests converts the development of new coal deposits to very difficult and dangerous business.
-
-
-
Saturation and contamination dependence of electrical properties in the MHz range
Authors C. Urban, J. Schonart and A. WellerThe application of electrical and electromagnetic measurements on geotechnical and environmental problems requires detailed knowledge of the influence of lithology, pore structure and pore filling on the electrical properties of rocks. Former investigations at frequencies up to 1 MHz (Kulenkampff, 1994) have shown that frequency dependent electrical measurements yield especially information about parameters describing the pore structure due to polarization effects caused by electrochemical reactions at the internal surface. Only for highly porous media, pore filling considerably affects the complex conductivity spectra. This is one reason for the strong deviations between the results of measurements and mixing formulas like complex reflection index method (CRIM) or Bruggernann-Hanai-Sen-Shen (BHSS) which ignore surface effects (Urban, 1995). The aim of the presented work is to examine the influence of saturation and contamination of samples of different lithology and known pore structure on the electrical properties in the Mhz range to provide a data base for the interpretation of electromagnetic field measurements. Furthermore, the investigations should result in a quantification of the relation between electrical parameters and pore structure controlling the hydraulic and diffusive transport of pore fluids.
-
-
-
Measurements and estimates of tracer diffusion in the NW Mediterranean Sea
Authors J. M. Redondo, M. O. Bezerra, M. R. Soler and I. R. CantalapiedraThe eddy diffusivities in the ocean exhibit a large variation and show a marked anisotropy, not only horizontal values are much larger than vertical ones but there is a strong dependenee on the spatial extent of the tracer dye or pollutant. In the case of oil spilIs, these are strongly influenced by the buoyancy and horizontal diffusion depends on ambient factors such as wave activity, wind and currents.
-
-
-
The main problems of the technogenic radioactive water reservoirs safety on Techa River (South Ural)
Authors G. Batrak and S. SemenovDuring the creation of armament plutonium at the PO Mayak in the South Ural, the acute problem of utilization and storage of low-Ievel liquid nuc1ear wastes arises. The technology allows to discharge them into the open storage reservoirs without hydroisolation of reservoirs, whereas in the USA, bottom and sides of reservoirs are cemented or paved with asphalt. During the exploitation of storage reservoirs, there arises the danger of their overfilling or out-break, as weIl as of seepage through their body and foundation. The problem will be less acute, if the ways of rational reservoir control are found.
-
-
-
Georadar, electromagnetic, and magnetic studies of a landfill and its host sediments
Authors R. De Iaco, H. Horstmeyer, D. E. Boerner, F. Lehmann and A. GreenMany landfills are currently causing severe environmental problems, such as ground-water contamination. In view of the large number of poorly documented landfills, fast and inexpensive methods for investigating the shallow subsurface are becoming increasingly important. We have tested a variety of non-intrusive geophysical methods at a landfill located within glacio-fluvial sediments in northwestern Switzerland. Three-dimensional georadar, frequency-domain electromagnetic (EM31), and mag net ie surveys have been conducted over part of the landfill and adjacent undisturbed ground. Dense sampling of the subsurface, a self-designed algorithm for sealing the georadar data in a way that suppressed prominent noise, and application of NMO corrections were important steps for obtaining detailed and accurate images of the investigated area. From borehole information, reflections from interfaces between different gravel sheets and from the top of the underlying lacustrine layer could be identified. Timeslices revealed a general SW-NE flow-direction of the ancient river system that deposited the gravels and sands. The lacustrine sediments are an aquitard in this region. Interpolation of the aquitard, an important barrier for contaminants emanating from the landfill, between surveyareas northwest and southeast of the landfill, provide us with an estimate of the maximum dep th of the waste disposal site.
-
-
-
Evaluation of an old waste disposal site contamination, using electrical methods
Authors F. P. O. Figueiredo and A. I. S. AndradeA case of chemical pollution induced by an abandoned disposal site located on an alluvial plain has been investigated through geophysical prospection. The aim of the geophysical survey was the delimitation of the shape/dimension of the conductive contaminated plume, .which the landfill has been inducing. The plume goes down to a depth that ranges between lOm to 80 mand the resistivity of the contaminated sediments is approximately 50 ohm.m.
-
-
-
The use of geophysical techniques for the detection and characterization of landfill in areas of urban development
Authors A. Granda and J. C. CamberoThe growth of some Spanish eities has created the need to develop urbanistic projects in its surroundings, on lands that in many cases have been affected by the activity of the city itself, and specifically by the existence of garbage deposits or different kinds of waste products. The nature and characteristics or these waste deposits usually differ in every case, since they may correspond to urban solid waste with a great presence of organic matter, or inert spillings caused by industrial activities. The existence of these deposits is known with a higher or lower degree of accuracy in some cases, while it is absolutely unknown in others, because the old deposits were conditioned for a subsequent use of the ground in a way that after several years it would be impossible to identify their location just by observing the site.
-
-
-
Non-invasive geophysical mapping of chemical waste deposits and flow-paths
Authors R. D. Ogilvy, D. Beamish, P. I. Meldrum and R. MossA non-invasive geophysical survey has been undertaken to characterise the extent of contamination associated with chemical wastes deposited in dis-used sandstone quarries. The specific aims of the geophysical survey were: - to delineate the concealed edges and base of the quarries prior to the siting of sampling and monitoring boreholes - to assess whether waste fluids had invaded the surrounding sandstones and to map these contaminant migration pathways, prior to intrusive sampling A secondary aim was to assess the general capabilities and reliability of geophysical methods for waste site characterisation in this environment.
-
-
-
Optimum model in 2D geoelectrical imaging : example from a dump site with high resistivity contrasts
Authors A. I. Olayinka and U. YaramanciModelling and inversion of synthethic data over 2D geologie models have shown that, at high resistivity contrasts, there could be an increase in the model misfit between the inverted model and the true model for successive iterations. Hence, the optimum model is attained at a low iteration number. A case history, from data measured over a waste dump site, is given in which the optimum model is the structure at the second iteration; the inverted resistivities are very low at less than 30 Om down to a depth of about 10 m. These are consistent with the analyses of surface - and ground - water which indicate the presence of a low resistivity contaminant.
-
-
-
Electrical tomography survey of a landfill site
Authors M. Pokar and M. H. LokeThere are an estimated 230 landfills in Malaysia, some of which are located near communities and water sourees. Besides contamination of ground water due to chemical leachates, gas migration can also be a serious problem. Landfill gases are formed during the decomposition of organic wastes and consists of a mixture of methane (C~), carbon dioxide (C02), nitrogen (N2) and volatile organics. The use of 2D electrical tomography surveys (Griffiths and Barker 1993) to map various features in landfill sites was investigated in this research. Tests with synthetic data for different landfill models were first conducted. Surveys were also carried out to delineate the various fill materials, map leachate movement and gas accumulations. The results from two of the survey lines with possible gas traps are given in this paper.
-
-
-
The conductivity structure beneath the industrial waste site Mellendorf as derived by radiomagnetotellurics (RMT)
By B. TezkanIn Europe, especially in Germany, the application of geophysical methods to waste site explorat ion becomes inereasingly important since their contribution 1.0 the pollution risk estimation has been recognized. Applied geophysics can offer many techniques for the non-invasive mapping of waste sites and should be considered as a main source of information about interesting borehole locations. Between 1960 and 1989 an automobile company used a sand pit located in Mellendorf near Hannover for the disposal of magnesium dross and other industrial waste. After its recultivation, the waste site was covered by a layer containing soil, sand with gravel and clay. Fig.1 shows a geological stratification beneath the survey area derived from boreholes on the waste site (Renno and Christofzik, 1987).
-
-
-
Three-dimensional inversion of induced rolarization data from simulated waste
Authors A. Weller, M. Seichter and W. FrangosThe Idaho National Laboratory (INEL) Cold Test Pit (CTP) has been carefully constructed to simulate stored hazardous waste occurrences. In order to test various methods of non-invasive subsurface waste location techniques, a simulated waste pit has been constructed using safe materiaIs, and designed to resembie old waste pits as closely as possible. This Cold Test Pit (CTP) has been investigated by a number of workers using several different methods. The present work was carried out as part of the Electromagnetic Integrated Demonstration (EMID), which also inc1udes an assortment of electromagnetic techniques (pellerin and Alumbaugh, 1997). The CTP was constructed as a 13 x 70 m trench, segmented by transverse berms into cells. The southern-most cell investigated in the EMID project, contains stacked drums and boxes and a variety of randomly positioned barrels, pipes, a large metal tank, etc., this location is referred to as the Large Object Pit (LOP). The buried drums located in the center of the trench inc1ude both cardboard and metal drums containing scrap metal and nonmetallic materiais. The cell is described as being a three-meter waste seam with about 1.5 m of soil cap, thus the depth of the bottom of the waste is about 4.5 m. The cap is composed of c1ay-rich soil trucked in from other areas of the INEL complex. Host material is local soil overlying resistive Snake River basalt.
-
-
-
Assessment of non controlled land-fillings by geochemical and geophysical methods. Llobregat Delta (Barcelona, Spain).
Authors X. Font, A. Navarro, L. Rivero, A. Casas, J. Noguera and F. MartînezThe problems associated with municipal, abandoned or non-controlled landfills are of general concern, specially because of the interactions between the hazardous content of the leachates derived from them and groundwater. MacFarlane and others (1983) were the pioneers on this type of studies, later on, Cherry and others (1996) did more specific research on heavy metal thermodynamic with emphasis on providing data to assess or validate mathematical models at Borden landfill site (Canada). The main objective of this study was to characterise contaminated sites provoked by noncontrolled sand and gravel extraction quarries filled with urban, construction, industrial and chemical wastes. Using combined geochemical and geophysical data is possible to characterise contamination extension of the groundwater superficial aquifer and to deduce possible implications of water flux through landfillings.
-
-
-
Geophysical measurements for assessment leakage risk in underground waste storage
By H. MarcakThere are hundreds of kilometres of underground tunnels in the coal mining are as in Upper Silesia and in the copper mining area in Lower Silesia. This empty underground area seems to be very good place for waste deposits. Materials with different levels of toxicity may be stored in these places, when the safety of the place are taken into account. Furthermore according to polish law a system of barriers must be constructed such sites. However, a catastrophic scenario must be considered. In this scenario, the stability of underground caves are disturbed; barriers are destroyed, water fIows into caves and contaminants leave the storage. Consequently, the design of an environmentally safe underground storage system and the control of its safety is achallenge for research workers.
-
-
-
Diagnosis of waste landfills by infrared thermography
Authors C. Sirieix, L. Rouvreau, L. Bertrand, M. Frappa and C. BloquetIncreasingly strict legislation concerning the management and storage of waste is leading to the creation of a new generation of landfills, as weil as to the remediation or closure of older sites. Thus there is the problem of the long term surveillance of the old sites and the control of the new one. The mass of waste is often a black box in which intense, complex and poorly understood physico-chemical processes occur. If they cannot be controlled, they must be regularly monitored in order to intervene as rapidly as possible if the process warrants it. The thermal activity of a site is directly related to exothermal chemical activity of waste. This chemical activity produces biogases who accumulates in some particular places. Landfill managers have difficulty in characterising site activity and its change with time. There are two phenomena to control : accumulation of biogases like methane and leakage in the new sites and increasing temperature with the risk of fire underground in the old sites. Infrared thermography can be used to establish this thermal activity. We'lI described this two kind of applications.
-
-
-
Significance of magnetic and induced polarization responses over municipal solid waste facilities
Authors N. Abu-Zeid, M. Marcheti, G. Santarato and M. PaiolaImpacts of improperly managed old Municipal Solid Wastes (MSW), especially those uncontrolled and/or illegal, not only deteriorate the environment by posing it to hazards leading to soil and groundwater eontamination, but also grave the economy as remedy costs ean be very high. Therefore, the best way to proteet the environment is to minimise negative impacts of MSW and to associate them with an efficient monitoring system not only during the feasibility study but also during the whole life of the facility.
-
-
-
Application of electromagnetic reflection method (EMR) to investigate confined and perched aquifers
By F. BahloulThere are many reasons to drill a hole, for example test borings for local geological sampling, groundwater monitoring or shotpoint drilling for seismic investigation. Previous knowledge about areas endangered by artesian water is important to avoid drilling in these areas. Undesired artesian water outflow can be dangerous and causes a lot of damages. Perched and confined aquifers are common in areas of push moraines due to the interlocking of glacial sand, till and boulder clay. The groundwater levels change abruptly in steps because of steeply dipping thin layers with low perrneability between the sand layers ofthe aquifers. Owing to the differences of the electrical properties (dielectric constants and conductivity) between soils or rocks and water, electromagnetic energy is reflected at boundaries of material with different water content, since the water changes the relative permittivity of most soils or rocks by a factor 5-6. This fact makes the groundwater table a good reflector of electromagnetic energy if it is associated with a steep change in the soil's water content. The aim of the present paper is to demonstrate the possibility of using electromagnetic reflection method (EMR) to detect some groundwater table anomalies (mainly steps or a discontinuity) and its interpretation combined with the known geological and hydrogeological information to predict artesian waterand perched aquifers.
-
-
-
Geophysical investigations of alluvial aquifers in Zimbabwe
More LessGeophysical investigations were carried out on shallow alluvial aquifers in conneetion with sand rivers in Zimbabwe. The primary methods used were OC resistivity imaging and ground penetrating radar (GPR). The investigated sites are situated on so called sand rivers. i.e. rivers with a seasonal surface flow. The strata of principal interest, for local water supply and subsistence irrigation purposes, are alluvial sands present in the active stream channel or beneath flood plains. The alluvium in the present stream channels consists of coarse grained sand, generally with a groundwater table within a couple of metres depth. These shallow aquifers are widespread in the dryer parts of Zimbabwe, as well as other countries in the region. Since resource development is possible with locally sustainable technology, it is of high potential value. Investigations were carried out at two sites on the Umzingwani River and one on the Shangani River with results that agree well, which is also supported by previous research (Owen 1989)'. The geophysical surveys have been presented in detail by Einarsson et al. (1994), Ekström et al. (1996) and Beekman and Liberg (1997).
-
-
-
Geophysical imagery of strand zone
Authors J. C. Courryl and P. WatremezThis work belongs to a project for the use of geophysical techniques in the strand zone (i.e. the area situated between the low and the high tide, by extension in our work, the area between the lower level of sea and the back dune). A large part of French coasts are constituted of beach dunes which are moved by winds. The main problems of coast management are water resources management due to the saline intrusion, bedrock mapping for civil engineering problems and dune stabilization. For structural geology, usual geophysical techniques are seismic, but which is expensive. Saline intrusion are detected with electrical sounding, but is a punctual technique. The aim was to use low cost continuous methods. We tested a methodology coupling continuous electromagnetic techniques and electrical soundings. We supposed that this combination of techniques could answer to the problem of bedrock mapping and water levels detection.
-
-
-
Geophysical prospecting of bedrock aquifers in Finland
By E. LanneThere are about 5.2 million inhabitants in Finland, most of which live in the Southernmost part of the country. 86 per cent of the population is connected to cooperative or public water supplies. In 1995, the average water consumption was about 260 litres per capita per day. The proportion of groundwater of the total water withdraval is about 58 per cent. The official water policy prefers ground water aquifers, because the quality of surface-water varies seasonally and is exposed to environmental risks.
-
-
-
Application of the surface proton magnetic resonance method for the detection of fractured granite aquifers
Authors A. V. Legchenko, J. M. Baltassat, A. Beauce, M. A. Makki and B. A. AI-GaydiThe Surface Proton Magnetic Resonance (PMR) method was developed in Russia in early eighties for investigation of sedimentary aquifers. However, the magnetic resonance signal is also produced by water in any other types of rocks. It makes possible application of the PMR for water detection in fractured aquifers where traditional geophysica! methods are less effective. Results of the water prospecting project carried out in Saudi Arabia are presented. Investigated aquifers there are essentially composed of metasediments ("black slate"), granite, grandiorite and diorite. During the hydrogeological survey achieved by ANTEA in April of 1996 two promising areas for water supply were emphasized. In order to detect fractured zones these areas were then studied by BRGM using the Horizontal Loop Electromagnetic (HLEM) method. As HLEM anomalies nothing teil us about water in the fractures, exploration boreholes were also drilled and tested where these anomalies were observed. Totally 17 PMR soundings were carried out in April of 1997 using the NUMIS PMR instrument. Eight of them were performed just close to existing boreholes which have various yields ranging from 0 up to 22 m3/h. The aim of these measurements was to calibrate the PMR response. The other soundings were performed along profiles in order to investigate the lateral extends of the waterful fractured zones. Generally a good correlation between drilling and PMR results was observed. Thus, it was demonstrated that the PMR is a useful tooi for optimal location of productive boreholes in a fractured granite hydrogeological environment. For example, referring to the project in Saudi Arabia, if the PMR measurements would have been carried out at an intermediate stage between the HLEM survey and the drillings, the number of boreholes could be reduced at least twice without any loss of information.
-
-
-
Application of geophysical methods to quantify hydraulic parameters in a complex porous aquifer a case history Pfynwald - Wallis - Switzerland
Authors R. Monnet, D. Chapellier and J. FurrerThe characterization of boundaries and hydraulic properties of the layers through which the water flows in complex saturated porous aquifers is only possible through numerous measurements in wells and boreholes including also intensive geophysical surveys. Within the framework of the research project entitled « Fluid and mass transport in porouss medium: quantification and comparison of hydrogeological. geophysical and hydrochemical methods. Example of the alluvial aquifer in The Bois de Finges (Pfynwald) » financed by the Swiss National Science Foundation, a 30 meters deep borehole was drilled in the vicinity of four shallower holes reaching 15 meters.
-
-
-
Combined electrical resistivity and pumping test modelling
Authors J. Moore, R. Barker and A. HerbertContaminant transport issues, coupled with advanced numerical modelling techniques have led to an increased demand for quantitative descriptions of groundwater systems. To determine the distribution of hydraulic parameters, resistivity techniques have been employed to complement conventional hydraulic tests. The electrical resistivity of a saturated rock or sediment is a function of the porosity, the electrical resistivity of the saturating fluid, the resistivity of the solid rock or sediment. the surface conductance of the rock or soil and the tortuosity of the electrical and fluid path. It is generally assumed that for most formations with low c1ay content the electrical current is conducted electrolytically through the pore waters (Urish, 1981). This has led to numerous attempts to define a relationship between electrical resistivity and hydraulic conductivity. However, both direct and inverse relationships have been reported, thus highlighting the dominanee of surface conductance effects and the problerns incurred by neglecting its importance (Huntley, 1986).
-
-
-
High resolution electrical monitoring of fluid flow through the unsaturated zone of a sandstone aquifer
Authors V. Hatzichristodulu, R. Barker and J. TellamThe unsaturated zone is very important, not only in water resource evaluation but in contaminant transport as weIl, particularly in siting waste disposal facilities and in remediating contaminated sites. Therefore, new approaches are required so that the three dimensional detail of the zone is determined. The aims of this work are: • to test the usefulness of high resolution electrical tomography in mapping the three dimensional movement of water in the unsaturated zone and • to provide a further understanding of the processes involved in the unsaturated zone flow. To achieve the above, a high resolution imaging system was installed at a research site at the University of Birmingham. The research site consists of an Environmental Agency observation borehole and 3 piezometers, together with unsaturated zone instrumentation which has enabled groundwater levels and moisture contents to be monitored for the last two years (Digges La Touche, 1998). Two more boreholes will be drilled at the site later this year. The new imaging system is used to monitor fluid movement in the unsaturated zone over an extended period of time and during short term pumping tests. The observations may be related to the properties of the subsurface and variations in recharge.
-
-
-
Tests of the SGW-NMR technique within two aquifer characterization projects in the Iberian Peninsula
Authors J. Roy, A. Marques da Costa, M. Lubczynski and C. OwuorThe management of GroundWater (GW) resources implies, ahead of any exploitation scenario, an inventory and characterization of such resource. This is a multidisciplinary task, in which a whole array of techniques are used but the Surface version of the GroundWater Nuclear Magnetic Resonance teclmique (SGW-NMR) appears to have a potential role. NMR techniques are used in state-of-the-art applications such as medical imaging, chemical structure analysis and hydrocarbon resources exploration and quantification. The SGW-NMR technique is an implementation of this technology for the purpose of non-invasive investigations of groundwater from the earth's surface. The SGW-NMR technique has been described, among others, by Goldman et al. (1994) and Lieblich et al. (1994). The introduetion of a commercial SGW-NMR system by IRIS Instruments in the Spring of 1996, marketed under the name of NUMIS PMR, was followed with interest at ITC and elsewhere. Such interest is based on the potentialof this non-invasive technique in the domain of groundwater exploration and quantification. In fact, of high interest to us is its capacity to identify the hydrostratigraphy of the flow system, to quantify the effective porosity and to provide information related to pore size distribution and therefore to hydraulic conductivity of in-situ subsurface materials from surface measurements only (i.e. without using boreholes). This information is available in a sounding mode (i.e. as a function of depth) and is measured over a large volume of materials (106 to 107 m') so that seale effect, as observed with point souree hydraulic determinations i.e. pumping tests, are minimized (Lubczynski et al, 1997).
-
-
-
A combined application of high resolution reflection seismics and TDEM for detailed study of the coastal aquifer of Israel
Authors V. Shtivelman and M. GoldmanAn integrated geophysical study, including high-resolution reflection seismies and TDEM, was recently carried out at several sites along the Mediterranean coast of Israel (Fig. 1). The coastal aquifer consists of the Quatemary sequence of marine and continental deposits composed predominantly of calcareous sandstone (the Kurkar unit) and including a number of clay layers. Calcareous sandstones are generally porous and hydrologically conductive and considered aquifers, whereas clays are impermeable and act as aquicludes. In the places where the clays are thick and extensive enough, they divide the aquifer into distinct subunits. Fig. 2 represents lithologicallog from borehole 12/A in which various Kurkar units are designated as KAl through KA7. The sequence rests on impermeable black shales and clays of the Saqiye group of Pliocene - Miocene age. The aquifer suffers from severe salinization caused by seawater encroachment reaching as far as 1 km from the sea shore. The general objective of the geophysical survey was a detailed study of the coastal aquifer and, in particular, subdivision of the aquifer into subaquifers separated by impermeable units and evaluation of water quality within each subaquifer. At first stage, the survey was carried out at the Nitzanim site, where several observational wells were located and used for correlation purposes. Then the survey was continued to other areas where the hydrogeological control was limited by a single well at each site. The results of the survey are represented here by an example of the Nitzanim area.
-