Environmental and Geotechnical Control and Investigation with E and EM Techniques Chairpersons: A. Viljanen and J.M. Travassos 1.1 ELECTRICAL AND ELECTROMAGNETIC METHODS FOR ENVIRONMENTAL AND GEOTECHNICAL INVESTIGATIONS IN THE YEAR 2000 (INVITED REVIEW PAPER) Louise Pellerin University of Utah, Energy and Research Institute, Salt Lake City, Utah 84112, USA lpellerin@egi.utah.edu 1.2 DETECTION OF A HYDROCARBON CONTAMINATED LAYER NEAR THE RAFFINERY BRAZI/ROMANIA BY USING SHALLOW EM-TECHNIQUES B. Tezkan(1) and P. Georgescu(2) (1) Institute of Geophysics and Meteorology, University of Cologne, Germany (2) University of Bukarest, Romania tezkan@geo.uni-koeln.de Soil contaminations caused by hydrocarbons constitutes a problem of the reorganisation of closed factories, tank forms, and raffineries. It is neccessary to determine the kind and content of the contaminations. Soil samples lead to reliable result, but the detailed investigation of an area requires a large number of boreholes which are quite expensive. A test area close to raffinery Brazi was chosen. Due to several accidents in the raffinery the area is hydocarbon contaminated and an oil layer is expected at 5m depth with a thickness of 1m. A detailed radiomagnetotelluric survey was carried out in this area. Transfer functions were observed in the frequency range between 10-300 kHz. IP and DC measurements were also carried out on the same profiles. The data were interpreted by using 2D inversion techniques and the conductivity structure of the area was derived. The contaminated layer could be detected as a poor conductive zone in the gravel layer just about the groundwater table. The resolution of the contaminated layer at 5m depth was studied by using 2D forward model calculations which give an excellent test about the joint applicability of RMT with DC/IP methods for the detection of hydrocarbon contaminated soil. 1.3 LARGE GEOMAGNETICALLY INDUCED CURRENTS IN THE FINNISH HIGH-VOLTAGE POWER SYSTEM Antti Pulkkinen, Ari Viljanen, and Risto Pirjola Finnish Meteorological Institute, Geophysical Research Division, P.O.B. 503, FIN-00101 Helsinki, Finland antti.pulkkinen@fmi.fi Geomagnetically induced currents in the Finnish high-voltage power system were studied within a project between the Finnish Meteorological Institute and the Fingrid Oyj company in 1999-2000. Since it has been shown earlier that the Finnish system is not very sensitive to GIC, the project was mainly aimed to investigate the most extreme cases. The sum of the absolute values of GIC flowing through transfomers was specially chosen to the quantity describing the severity of geomagnetic event from the point of view of the power system. The study was divided into a two parts, 1. calculation of the geoelectric field and GIC using realistic ionospheric current models and the complex image method developed for a rapid computation of geomagnetically induced fields, and 2. calculation of the geoelectric field and GIC using the BEAR and IMAGE magnetometer network data. Geoelectric field distributions for real geomagnetic events were the main result of the study which can easily be applied for any power network configurations. Statistical occurrence of GIC at individual stations were derived with the help of the geomagnetic acticity index K at the Nurmijarvi Geophysical Observatory. GIC for events corresponding to each K index value were calculated and GIC statistics were derived based on the yearly K index statistics. 1.4p PROJECT ON GEOMAGNETICALLY INDUCED CURRENTS IN THE FINNISH NATURAL GAS PIPELINE A. Pulkkinen(1), A. Viljanen(1), K. Pajunpaa(1), R. Pirjola(1), L. Trichtchenko(2), and D. Boteler(2) (1) Finnish Meteorological Institute, Geophysical Research Division, P.O.B. 503, FIN-00101 Helsinki, Finland (2) Geological Survey of Canada, 7 Observatory Crescent, Ottawa, K1A 0Y3 Canada antti.pulkkinen@fmi.fi Geomagnetically induced currents in the Finnish natural gas pipeline network were studied in 1998-99 in co-operation between Gasum Oy company and the Finnish Meteorological Institute. The project involved theoretical considerations and measurements of the currents and pipe-to-soil voltages in the pipeline during geomagnetic disturbances. The theoretical part included application of the distributed source transmission line theory with new extensions that make it possible to treat an entire pipeline network affected by a realistic spatially non-uniform geoelectric field. Profiles of GIC and pipe-to-soil voltages were calculated for different geomagnetic situations. The current along the pipeline was recorded by using two magnetometers, one above the pipeline and one at the nearby Nurmijarvi Geophysical Observatory. The difference of these measurements is the magnetic field due to the current in the pipeline. The measured data were combined with theoretical model to derive statistics of the GIC occurrence in the pipeline system. 1.5p MODELLING OF SPACE WEATHER EFFECTS ON PIPELINES A. Pulkkinen(1), D. Boteler(2), R. Pirjola(1), A. Viljanen(1), and I. Yegorov(3) (1) Finnish Meteorological Institute, Geophysical Research Division, P.O.B. 503, FIN-00101 Helsinki, Finland (2) Geological Survey of Canada, 7 Observatory Crescent, Ottawa, K1A 0Y3 Canada (3) Russian Academy of Sciences, 36 Nakhimov Av., 117851 Moscow, Russia antti.pulkkinen@fmi.fi Variations of the geomagnetic field, one of the space weather effects, induce currents in conductors at the Earth's surface, e.g. in pipelines and power transmission systems. Accurate modelling of these geomagnetically induced currents is needed for risk estimations that are made by industry. Starting from the Maxwell equations, we show that currents and pipe-to-soil voltages can be solved by using tranmission line analogy. Especially, the distributed source transmission line theory is directly applicaple. The main advantage is that we can use methods familiar from the circuit theory, e.g. the Thevenin theorem. Then we can model discontinuities of a pipeline which could be difficult if started directly from the basic electromagnetic theory. The latest achievements have been the modelling of branches of a pipeline and inclusion of a spatially non-uniform geoelectric field. These new results make it possible to model the voltages and the currents in any pipeline network. 1.6p TELLURIC CURRENTS IN PIPELINES L.L. Vanyan and I.V. Yegorov Shirshov Institute of Oceanology, RAS, Moscow, Russia vanyan@geo.sio.rssi.ru Natural telluric currents are induced in the Earth by the geomagnetic disturbances caused by the ionospheric electric current systems. Considerable researches are directed to studding the physical process of a concentration of the telluric current in the well-conducting pipeline. In this connection the aim of the mathematical modeling is to predict the most dangerous localities of the pipeline. An effective technique for the mathematical modeling of the telluric current concentration in the pipeline was developed by Boteler, Pirjola et al. They used a simple analogy of pipeline and transmission line supposing the pipeline is surrounding by the equipotential surface. In the presented work, the problem is solved for the arbitrary electrical conductivity around the pipeline. The computer program, based on the combined method of solving the system of the differential equation for scalar electric potential in metal and 2D integral equation on the surface of the pipeline isolation, allows to take into account geographical distribution of the geomagnetically induced electric currents, real shape of the pipeline, geographical distribution of the Earth electric conductivity, real parameters of the protection including the places of damages. Results obtained for the case of the homogeneous space with the conductivity less 0.0001 S/m outside the straight pipeline showed an essential difference as compared with ones obtained by technique of Boteler. For values of the conductivity more 0.01 S/m results are close. 1.7p LABORATORY TESTS TO CHARACTERIZE THE CURRENTS INDUCED ON PIPELINES EMBEDDED IN 2D SOILS Ernesto Lopez and Ana Osella Dpto. de Fisica, Universidad de Buenos Aires, Conicet, Ciudad Universitaria, Pab. 1, Buenos Aires, Argentina osella@df.uba.ar Theoretical investigations were made to determine the corrosive effects of varying external geomagnetic fields on pipelines embedded in a 2D soil. They predicted an enhancement of the induced current when the pipe crosses to a more resistive soil and also showed a linear relation with the intensity of the external field. These facts implied two main risks. The first one is that the excess of currents could drain through the pipe to the soil and the other is related to the intensity of the currents, which could contribute to the degradation of the coating. Field investigations seem to confirm these predictions, but further studies should be required which allows controlling the influence of the different parameters. According to it, experimental tests were carried out in our laboratory. Pipes in different conditions (with and without coating) were embedded in media with lateral electrical discontinuities. The external field was simulated using a wave generator and measurements of the current flowing along the pipe were recorded at different points of the path to determine whether or not the induced currents follows the predicted pattern. Additional proofs were carried out to investigate if an accumulative process could take place and if so to what extent the induced current applied for a long time could damage either the pipe wall or its cover. 1.8p EXPLORATION OF A WASTE DISPOSAL SITE WITH RADIOMAGNETOTELLURIC, TIME-DOMAIN IP AND ANALYSES OF SOIL SAMPLES Stephan Recher, M. Hoenig, B. Tezkan, and F.M. Neubauer Institute of Geophysics and Meteorology, University of Cologne, Germany recher@geo.uni-koeln.de Since 1999, the collaborative research centre SFB-419 at the University of Cologne examines some of the potential effects and problems of pollution through case-studies taken from a densely populated industrial region in Germany. Solutions shall be proposed on the basics of scientific and medical analyses, simulations and predictions, taking into account social, economic as well as legal aspects. The geophysical component of the project uses electrical and electromagnetic methods for non- destructive characterization of waste disposal sites. On a waste site near Cologne/Germany radiomagnetotelluric and time-domain induced polarisation measurements were carried out at the same profiles. The RMT data were interpreted with 2D conductivity models. For the IP measurements the complete transient curve was recorded in the field using a transient electromagnetic system. A 1D inversion algorithm was developed to derive the Cole-Cole parameters from the recorded transients. At several locations at the site, where the models of RMT and IP data show anomalous features in conductivity and Cole-Cole parameters, drillings yielded soil samples which are examined in the laboratory for their physical parameters. The results offer the possibility to examine and calibrate the models of RMT and IP data. 1.9p ON THE INVESTIGATION OF HAZARDOUS WASTE SITES USING THE BGR HELICOPTER GEOPHYSICS SYSTEM B. Siemon(1), C. Stuntebeck(2,3), K.-P. Sengpiel(2), B. Rottger(2), and H.-J. Rehli(2) (1) Geophysik GGD, Hamburger Allee 12-16, D-30161 Hannover, Germany (2) Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, D-30655 Hannover, Germany (3) now at: IGM, TU Braunschweig, Mendelsohnstr. 3, D-38106 Braunschweig, Germany geophysikggd.hannover@uumail.de c.stuntebeck@tu-bs.de BGR conducted a R&D project "Modification of aerogeophysical instrumentation and data evaluation for hazardous waste investigation" funded by the German government from 1996 to 1999. The aim was to detect small buried objects using airborne electromagnetics and magnetics as well as to determine the geological and hydrogeological environment of the waste. A broad- band new EM system operating at five frequencies (0.38, 1.8, 8.6, 41, and 192 kHz) at higher dipole moments and with a novel calibration concept has been developed. The caesium magnetometer, a laser altimeter, and a positioning system were also installed in the EM bird and flown at reduced altitude down to 20 m where possible. The combination of reduced flight speed (100 km/h) and increased sampling rate (10 Hz) resulted in a sampling interval of less than 3 m. Weak signals on the order of 1 ppm (EM) and 0.1 nT (mag.) from buried objects can be detected automatically using new filtering and cross-correlation algorithms. A special test area containing typical buried waste was prepared to test the new equipment and software capabilities. After surveying the test area, several similar surveys as well as hydrogeological reconnaissance surveys were carried out on former military training areas in Germany. It was possible to detect relatively small waste occurrences, e.g., metallic objects of a steel drum size. Furthermore, the EM data were inverted into parameters of a layered ground. This information is used to determine the lithology of the waste sites and to locate channels for possible groundwater flow. 1.10p THE USE OF GEOPHYSICAL METHODS IN THE MUNICIPAL SANITARY LANDFILL OF GRAMACHO, DUQUE DE CAXIAS, RIO DE JANEIRO - BRAZIL: FIRST RESULTS Andre G. Guttmann, Sergio L. Fontes, Carlos R. Germano, and Emanuele F. La Terra Observatorio Nacional, Rio de Janeiro, Brazil sergio@on.br There has been an outgrowing concern with the environmental protection, and the water supply both in surface and in subsurface. The disposal of Municipal waste residue requires a special attention, due to the fact that it may be a source of water contamination. Geosciences are dealing in the last years with an increased use in its studies, mainly because of the original requirements of the technological development and urban growth. The new requirements are chiefly related to a way to balance the industrial and urban growth to the environmental protection. The integrated use of geophysical techniques could turn out to be an efficient methodology in the characterization and evaluation of environmental problems. The Municipal landfill of Gramacho located in quaternary terrains in the town of Duque de Caxias receives a daily average of 14.000t of waste and it holds an area of approximately 120ha. The main purpose of this study consists of the use of different geophysical methodologies to characterize a part of this landfill. A fine grid in the area is being covered by a combination of geophysical methods: TEM and HLEM, magnetics, eletroresistivity, induced polarization, etc. First TEM results evidenced a very conductive shallow surface, with resitivities lower than 10 ohmm for depths down to 100 m. 1.11p PROSPECTS OF RMT BOAT-BORNE SURVEY USING IPI-1000 DEVICE WHEN STUDYING OF WATER CONTAMINATION Mikhail Pertel, Jaroslav Nikiforov, and Alexander Saraev St. Petersburg State University, 7/9, Universitetskaya nab., St. Petersburg, 199034, Russia elmag@elmag.ecri.pu.ru Water contamination creates a number of significant ecological problems in urban industrialized regions. For a control of ecological conditions on lakes, rivers and coastal marine zones it is necessary to use the express methods of water contamination study, permitting to receive the information from the vast water spaces. The significant perspective has the boat-borne modification of radiomagnetotelluric (RMT) method. The physical fundamental of this method application at the water contamination study is the essential difference of resistivity of pure and contaminated water. The resistivity of contaminated water decreases in 10-100 time depends from degree of mineralization. St. Petersburg State University has the significant experience in the development of RMT instruments. The IPI-1000 device for foot, car- and boat-borne surveys allows to measure of apparent resistivity and phase of impedance in frequency range of 10 to 1000 kHz. For foot survey both grounded and ungrounded electrode lines are used. In St. Petersburg the ecological conditions are complicated by uncompleted construction of protective facility (dam). As the result of it there are some difficulties in natural circulation of marine waters and contaminated zones are created. The measurements in profile of latitudinal direction on Gulf of Finland intersecting dam were made using IPI-1000 device. Horizontal components of electrical field were measured by asymmetrical floating antenna and magnetic fields - by magnetic antenna. The curves of apparent resistivity and phase of impedance were obtained and two areas were mapped. First one is situated in western direction from the dam and has the predominance of marine water with apparent resistivity from 1 to 3 Ohmm. Second - in the eastern direction from the dam with predominance of fresh water of Neva river. Depending from degree of contamination the apparent resistivity is changed in this case from 90-110 Ohmm up to 20-30 Ohmm. 1.12p DETERMINATION OF HYDROCARBON POLLUTION BY TDEM Valeriya Hallbauer-Zadorozhnaya(1) and Alexander Bessonov(2) (1) Terra Sounding and Analytical Pty Ltd, Somerset West, South Africa (2) Nizhnevlzhsky Geology and Geophysics Research Institute, Saratov, Russia dkh@mweb.co.za Contamination of aquifers in Quaternary sediments by hydrocarbons in the vicinity of Saratov, Russia, was suspected. Methods were sought to enable the positioning of the polluted area as well as contouring of the degree of pollution. Hydrocarbons in geological environments produce an IP effect when EM methods are applied. This was confirmed by field tests using TDEM. Test bore holes showed the presence of hydrocarbon films around mineral particles as well as contents of such compounds in the groundwater. Data were collected from 70 field stations along several profiles with lengths of up to 200 m., using a co-axial transmitter/receiver loop of 5x5 m. Mathematical modeling, assuming thin, polarizing conductive planes and, the interpretation of the TDEM curves by s-plane inversion were the main stations in the interpretational cycle. It allowed the determination of the electrical resistivity of each layer within a cross section as well as the polarizability and decay constant. The layers containing hydrocarbons were identified by their higher resistivity, 5-7 Ohm m. The polarizability of this zone is 25-35 per cent with a decay constant of 1.8 x 10-4 sec. The surface of the polluted layer roughly follows the relief of the underlying Cretaceous sediments. This survey demonstrates the ability of TDEM measurements to detect and delineate hydrocarbon pollution by the polarizing effect of such compounds in aquifers.