Assessing a fractured landfill cover using electrical resistivity and seismic refraction techniques

Geophysics ◽  
1991 ◽  
Vol 56 (11) ◽  
pp. 1896-1904 ◽  
Author(s):  
P. J. Carpenter ◽  
S. F. Calkin ◽  
R. S. Kaufmann
Keyword(s):  
Electrical Resistivity ◽  
Seismic Refraction ◽  
Seismic Energy ◽  
P Wave ◽  
Velocity Inversion ◽  
Landfill Cover ◽  
Geophysical Surveys ◽  
Resistivity Variation ◽  
Cover Thickness ◽  
Azimuthal Resistivity

Fracturing or erosion of landfill cover materials may lead to escape of landfill gases and creation of leachate through infiltration of surface water. Periodic geophysical surveys could be used to assess landfill covers noninvasively and identify fractured or thinned areas. Models derived from electrical resistivity and seismic refraction measurements were evaluated over various portions of a closed municipal landfill in west surburban Chicago. Resistivity soundings could not delineate cover thickness over areas of fractured or new cover where resistivity contrasts with the underlying refuse were minor. Cover thickness estimates accurate to within 0.7 m, however, were obtained over unfractured mature cover where resistivities were 10–20 ohm‐m higher than in the refuse. Azimuthal resistivity variations as large as 16 ohm‐m indicate opening of cover fractures during dry weather; these same areas showed little or no azimuthal resistivity variation under moist conditions. Strong absorption of seismic energy and a velocity inversion in the refuse prevented calculation of cover thickness from seismic refraction profiles using a sledgehammer source. However, higher direct P-wave velocities (740 m/s) characterized areas of intact cover and lower velocities (370 m/s) characterized highly fractured cover. Qp for cover materials ranged from 3 to 9 and did not differ between fractured and unfractured areas.

Integration of Multi-geophysical Approaches to Identify Potential Pathways of Heavy Metals Contamination - A Case Study in Zeida, Morocco

2020 ◽  
Vol 25 (3) ◽  
pp. 415-423
Author(s):  
Ahmed Lachhab ◽  
El Mehdi Benyassine ◽  
Mohamed Rouai ◽  
Abdelilah Dekayir ◽  
Jean C. Parisot ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Seismic Velocity ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Low Frequency ◽  
Electrical Current ◽  
P Wave ◽  
Low Resistivity ◽  
Refraction Tomography ◽  
Geophysical Surveys

The tailings of Zeida's abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and very low-frequency electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.

scholarly journals PRELIMINARY GULLY HAZARD ASSESSMENT USING 2D-ERT AND 2D-SRT GEOPHYSICAL SURVEYS: A CASE STUDY IN SOUTHEASTERN NIGERIA

2021 ◽  
pp. 49-65
Author(s):  
GN Egwuonwu ◽  
EI Okoyeh ◽  
DC Agarana ◽  
EG Nwaka ◽  
OB Nwosu ◽  
...  
Keyword(s):  
Seismic Refraction ◽  
P Wave ◽  
Lateritic Soil ◽  
Risk Level ◽  
Clayey Sand ◽  
Southeastern Nigeria ◽  
Velocity Models ◽  
Refraction Tomography ◽  
Geophysical Surveys ◽  
Oriented Parallel

Two-dimensional Electrical Resistivity Tomography (2DERT) and Seismic Refraction Tomography (2DSRT) were concurrently applied in assessment of a gully site with the view of assessing its stability and risk level. Eight profile lines oriented parallel and perpendicular to the boundary of the gully were surveyed. As a result, apparent resistivity model tomograms in the range of 1-9,000 and p-wave velocity models in the range of 300-700 were obtained from the two techniques respectively. Interpretation of the models obtained show predominance of unconsolidated clay, shale intercalates, clayey sand, sandy clay and weathered lateritic soil at shallow depths. Low amplitude undulating refracting layers, landslide slip subsurface and lose horizons were also delineated at shallow depths. The predominance of weak, clayey and unconsolidated lithology at the gully site suggests evidence of unstable gravitational equilibrium which imply environmental hazard. The plausible deductions made from the two

Geophysical mapping of gypsum for exploration of reserves in the Nong Bua area of Thailand

2020 ◽  
pp. qjegh2019-180
Author(s):  
Rungroj Arjwech ◽  
Mark E. Everett ◽  
Sakhon Saengchomphu ◽  
Kittipong Somchat ◽  
Potpreecha Pondthai
Keyword(s):  
Electrical Resistivity ◽  
Construction Projects ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Raw Material ◽  
P Wave ◽  
The Core ◽  
Micro Cracks ◽  
P Wave Velocity ◽  
Increasing Demand

The increasing demand for gypsum as a raw material for construction projects motivates exploration for additional reserves. Electrical resistivity tomography (ERT) and seismic refraction geophysical methods, augmented with borehole and laboratory measurements on core samples, are used here to delineate the top, bottom and lateral boundaries of an important gypsum ore deposit in Thailand, an economically developing region. The gypsum-bearing formation is found throughout the study area to have an irregular upper boundary on account of karstic dissolution processes. The deeper transition from gypsum to anhydrite, however, is not constrained by the measurements. The P-wave velocity measured in the field is consistent with the core specimen measurements. The electrical resistivity of the core specimens, however, is substantially higher than the values measured in the field. The specimen measurements may depend on the presence of micro cracks, whereas electrical resistivity in the field may be affected by the enclosing clay-rich materials.

scholarly journals Geophysical site assessment of an active urban development site, southeastern suburb of Cairo, Egypt

2020 ◽  
Vol 54 (1) ◽  
pp. qjegh2018-151
Author(s):  
N. I. Medhat ◽  
M. Atya ◽  
E. A. Ragab ◽  
A. A. El-Kenawy ◽  
M. Abdel Zaher ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Structural Damage ◽  
Residential Buildings ◽  
Seismic Refraction ◽  
Urban Site ◽  
Site Assessment ◽  
Near Surface ◽  
Geophysical Surveys ◽  
Quarry Blasting ◽  
Ground Stability

There has been significant structural damage of newly built residential buildings in Quarter-27 District in the SE of Cairo, Egypt. A nearby active limestone quarry may also be affecting ground stability. This paper shows how a near-surface geophysical survey could characterize the site, unusually after the initial housing construction had already been undertaken. Geophysical surveys included seismic refraction (acquired between phases of quarry blasting), electrical resistivity and ground penetrating radar (GPR) 1D and 2D datasets. Geophysical results produced maps of a 3D ground model that also included water table depth, known major faults and a saturated layer that may have caused the building damage. Of the geophysical techniques trialled electrical resistivity tomography and GPR data were deemed optimal. This study shows that it is possible to undertake geophysical surveys to characterize a restricted urban site development.

scholarly journals Detection of Cover Collapse Doline and Other Epikarst Features by Multiple Geophysical Techniques, Case Study of Tarimba Cave, Brazil

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2835
Author(s):  
Yawar Hussain ◽  
Rogerio Uagoda ◽  
Welitom Borges ◽  
Renato Prado ◽  
Omar Hamza ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Low Frequency ◽  
Least Square ◽  
P Wave ◽  
Positive Anomaly ◽  
Refraction Tomography ◽  
Collapse Doline

Reliable characterization of the karst system is essential for risk assessment where many associated hazards (e.g., cover-collapse dolines and groundwater pollution) can affect natural and built environments, threatening public safety. The use of multiple geophysical approaches may offer an improved way to investigate such cover-collapse sinkholes and aid in geohazard risk assessments. In this paper, covered karst, which has two types of shallow caves (vadose and fluvial) located in Tarimba (Goias, Brazil), was investigated using various geophysical methods to evaluate their efficiency in the delineation of the geometry of sediments filled sinkhole. The methods used for the investigation were Electrical Resistivity Tomography (ERT), Seismic Refraction Survey (SRS), Seismic Refraction Tomography (SRT) and the Very Low Frequency Electromagnetic (VLF-EM) method. The study developed several (2D) sections of the measured physical properties, including P-wave velocity and electrical resistivity, as well as the induced current (because of local bodies). For the analysis and processing of the data obtained from these methods, the following approaches were adopted: ERT inversion using a least-square scheme, Karous-Hjelt filter for VLF-EM data and time-distance curves and Vp cross-sections for the SRS. The refraction data analysis showed three-layered stratigraphy topsoil, claystone and carbonate bedrock, respectively. The findings obtained from ERT (three-layered stratigraphy and sediment-filled doline), as well as VLF-EM (fractured or filled caves as a positive anomaly), were found to be consistent with the actual field conditions. However, the SRS and SRT methods did not show the collapsed material and reached the limited the depth because of shorter profile lengths. The study provides a reasonable basis for the development of an integrated geophysical approach for site characterization of karst systems, particularly the perched tank and collapse doline.

Foundation Evaluation of a Repeater Installation Building using Electrical Resistivity Tomography and Seismic Refraction Tomography

2019 ◽  
Vol 24 (1) ◽  
pp. 27-38
Author(s):  
B. Butchibabu ◽  
Prosanta K. Khan ◽  
P.C. Jha
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Seismic Refraction ◽  
P Wave ◽  
S Wave ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Refraction Tomography ◽  
Subsurface Layers ◽  
Geophysical Investigations

Geophysical investigations were carried out for evaluation of damage and to assess the possible causes for repeated occurrence of damage at one of the buildings constructed for oil pumping in the northern part of India. Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT) techniques were adopted for studying the subsurface of the area around the building with an objective of ascertaining the cause of damage. High resolution imaging was done using both the techniques in this investigation. ERT delineated the presence of low resistivity (2 ohm-m) water filled voids below the structures and mapped different subsurface layers such as sandy soil, clay and sandstone in the study area. SRT revealed P-wave velocity ( V P ) of the subsurface medium in the range of 400–3,400 m/s. Corresponding densities and S-wave velocities ( V S ) were determined based on Gardner's and Castagna's relationships. Subsequently, the V P , V S and the modulus values were used in estimating compressibility of soil and rock strata. Results showed near surface layers were characterized by high compressibility (26.673 × 10 −5 Pa −1 ), decreases with depth. This paper presents the details of the site, techniques used in the investigation and correlation of geophysical results with lithological information, and the subsequent analysis for understanding the distress in the subsurface of the study area.

scholarly journals Multidisciplinary Approach to a Recovery Plan of Historical Buildings

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Luciana Orlando
Keyword(s):  
Electrical Resistivity ◽  
Seismic Data ◽  
Electrical Resistivity Tomography ◽  
Multidisciplinary Approach ◽  
Seismic Refraction ◽  
Lateral Velocity ◽  
Resistivity Tomography ◽  
Multiple Data ◽  
Geophysical Surveys ◽  
Joint Interpretation

The paper emphasizes the advantages of employing multiple data techniques—geology, GPS, surveys of cracking, boreholes, seismic refraction and electrical resistivity tomography—to image the shallow stratigraphy and hypothesize the cause of instability of an urban area. The study is focused on the joint interpretation of the crack pattern, topographic monitoring and the features of the underground, to define the area affected by instability and the direction of ground motion with the objective to advance a hypothesis on the cause of the instability of the area and to depict the main features. Borehole stratigraphies for a univocal interpretation of the lithology of electrical and seismic data and electrical resistivity tomography to constrain the interpretation of the lateral velocity variations and thickness of seismic bedrock were used. The geophysical surveys reveals to be complementary in the depicting of underground features. The study is approached at small and medium scale.

scholarly journals Characterization of carbonate rocks using seismic wave for tunnel design stability

2021 ◽  
Vol 325 ◽  
pp. 03002
Author(s):  
Hairin Taha ◽  
Nurul Atiqah Dzulkifli ◽  
Rohayu Che Omar ◽  
Ratih Fitria Putri ◽  
Rasyikin Roslan ◽  
...  
Keyword(s):  
Wave Velocity ◽  
Carbonate Rocks ◽  
Dynamic Properties ◽  
Seismic Refraction ◽  
P Wave ◽  
Sound Waves ◽  
Geotechnical Investigations ◽  
Geophysical Surveys ◽  
Tunnel Design ◽  
Primary Velocity

The design and construction of a tunnel depends on the mechanical properties of the rock mass around the tunnel. Seismic method can be used to characterize the dynamic properties of rocks. The technique is mostly conducted in geophysical surveys and geotechnical investigations. The method utilizes reflected sound waves that can be used to describe the dynamic properties of rocks. Physical properties of carbonate rocks such as water content, density, hardness, permeability, porosity, wave velocity and abrasivity can be assessed and estimated using P-wave velocity. One of the important characteristics in rock is its ability to remain stable. In this research, seismic refraction survey was applied to measure the strength of carbonate rocks for tunnel stability design. The findings revealed that the regression between the primary velocity and the uniaxial compressive strength R2 was 0.8592, indicating that the rock was firm and solid. Observation by physical visual test showed that the rock samples with yellowish-grey and light grey colours were categorized in the weathering grade II and III, respectively. The results have concluded that the rocks in the proposed area met the full requirements for tunnelling construction.

scholarly journals SOIL ELECTRICAL RESISTIVITY MAPPING IN THE FORMOSA CITY LANDFILL, GOIÁS STATE, BRAZIL

2015 ◽  
Vol 33 (2) ◽  
Author(s):  
Wllyane Silva Figueiredo ◽  
Carlos Tadeu Carvalho Do Nascimento
Keyword(s):  
Electrical Resistivity ◽  
Surface Water ◽  
Water Runoff ◽  
Average Increase ◽  
Central Brazil ◽  
Geophysical Surveys ◽  
Survey Line ◽  
Resistivity Variation ◽  
Surface Water Runoff ◽  
Soil Electrical Resistivity

ABSTRACT. The purpose of this work was to study the surroundings of a landfill in the Formosa city, Goi´as state, central Brazil, with respect to the values of the soil electrical resistivity. In the study area, two geophysical surveys were conducted, respectively in 2012 January and May. These studies were executed in the northwest edge of the landfill, which has smaller altimetry and therefore is the preferred site for effluents migration. The resistivity variation in the study area between the two data acquisition periods showed an average increase of approximately 47% in the value of this property in the transition from the rainy to the dry season. Independent of variation derived from the seasonal aspects of precipitation, there were observed areas with high and low resistivity along the survey line and whose positions are the same in both periods. The reasons for the occurrence of these areas are related to surface water runoff, which transports material in solution from landfill, including nearby roads, to its slope.Keywords: geophysical survey, effluent migration, surface water runoff. RESUMO. O objetivo deste trabalho foi estudar o entorno do Aterro Sanitário de Formosa, estado de Goiás, Brasil, mais especificamente sua borda noroeste, no que diz respeito aos valores da resistividade elétrica do solo. Na área de estudo foram realizados dois levantamentos geofísicos, respectivamente em janeiro e maio de 2012. Estes levantamentos foram executados na região noroeste do aterro, a qual apresenta as menores cotas e, portanto, é o local preferencial para migração de efluentes. A variação da resistividade na área de estudo entre os dois períodos de aquisição de dados mostrou que em média ocorreu um aumento de aproximadamente 47% no valor desta propriedade na passagem da estação chuvosa para a de seca. Independente da variação derivada dos aspectos sazonais de precipitação observaram-se, nos períodos de levantamento, áreas com alta e baixa resistividade ao longo da linha de aquisição de dados e cujas posições são coincidentes nos dois períodos. A justificativa para a ocorrência destas zonas está vinculada ao escoamento superficial de água, a qual, ao escoar na área do aterro, inclusive pelas estradas ali existentes, transporta material em solução que tende a se acumular no seu talude.Palavras-chave: levantamentos geofísicos, migração de efluente, escoamento superficial.

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