Geoelectrical mapping for improved performance of SUDS in clay tills

Bockhorn, Britta; Møller, Ingelise; Klint, Knud Erik S.; Jensen, Marina Bergen

doi:10.1007/s12665-015-4535-z

Cited by 5 publications

(5 citation statements)

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“…When doing this, the spatial information from the resistivity data is used to determine the boundaries between the individual geological units in areas without spear-auger information. In these areas, the changes in resistivity values have been used to locate the boundaries between deposits based on a local analysis of the lithology-resistivity relation and extrapolation from the spear-auger mapping points (Bockhorn et al, 2015). With this approach, it is possible to obtain significantly more precise boundaries between the units than if using the more sparsely distributed spear-auger data alone.…”

Section: Geological Mapmentioning

confidence: 99%

Development of a high-resolution 3D geological model for landfill leachate risk assessment

Høyer

Klint

Fiandaca

et al. 2019

Engineering Geology

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Groundwater protection and risk assessment of contaminated sites (e.g. abandoned landfills, industrial waste facilities, gasoline stations, and dry cleaners) situated in complex glacial landscapes are extremely challenging. A common method to assess the risks for leakage and contamination of groundwater and surface water is to develop hydraulic models. However, reliable models need to contain information about both the three-dimensional (3D) distribution of the deposits and their hydraulic properties. Environmental risk assessments therefore require highly detailed digital 3D geological models. In order to construct models with this degree of detail, dense data coverage with high-quality data is necessary. Many studies rely of few data sources, resulting in relatively sparse data. In this study we demonstrate how 6 different data sources can be combined to gain new insight on the geological history, which is central to the subsequent 3D geological modelling. The analyses in this study include (i) geomorphology, (ii) spear-auger mapping and near-surface electromagnetic induction data, (iii) borehole analyses, (iv) geoelectrical profiling, and (v) transient electromagnetic measurements. The study area is located on the island of Samsø, in the central part of Denmark, where a digital 3D geological model is constructed. The model consists of combined layer and voxel models and covers a small area (~ 1 km 2) surrounding a former landfill (Pillemark). The near-surface geology is characterized by a deadice landscape formed by glaciers during the Weichselian ice-age. By interpreting the new data it has been possible to update and revise the geological history, which was used during the development of a highly detailed 3D geological model. This model was constructed combining layers and voxels in order to better represent the complex geology and incorporate all the details provided by the different data sources. The novel geological understanding was used to update the risk assessment of the Pillemark landfill, where a remedial pumping today is ongoing. The immediate risk is related to the migration of landfill leachate downgradient through a lacustrine sandy aquifer and wetlands. Groundwater used for drinking water purposes is abstracted from an underlying sand and gravel aquifer (Tebbestrup formation), which is protected by a clay till (mid Danish till) found in the entire Pillemark area. A vertical hydraulic gradient from the upper to the lower aquifer indicates groundwater flow. However, the actual impact of landfill on the deeper aquifer has to be assessed by a detailed evaluation of the drainage system, pumping schemes and groundwater quality in the 3 area. The 3D geological model is an important step toward the development of a groundwater flow model, required in order to establish a water balance for the hydrogeological system and estimate the vertical transport.

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Section: Geological Mapmentioning

confidence: 99%

Development of a high-resolution 3D geological model for landfill leachate risk assessment

Høyer

Klint

Fiandaca

et al. 2019

Engineering Geology

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“…Geosciences 2020, 10, x FOR PEER REVIEW 3 of 19 [37,38]. Therefore, it would be advantageous if more generic similarities between geoelectric resistance, lithology, geotechnical in situ vane tests and infiltration capacity could be achieved covering larger areas.…”

Section: Study Locationsmentioning

confidence: 99%

“…To the author's knowledge, few Danish studies have tried to establish a quantitative and/or qualitative relationship between resistivity and infiltration capacity, lithology and geotechnical tests based on large-scale data sampling. Until now, only site-specific geophysical mapping has been used to investigate the best placement of SUDSs as well as their infiltration performance in Denmark [37,38].…”

Section: Introductionmentioning

confidence: 99%

Detailed Geophysical Mapping and Hydrogeological Characterisation of the Subsurface for Optimal Placement of Infiltration-Based Sustainable Urban Drainage Systems

Andersen

2020

Geosciences

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The continuous growth of cities in combination with future climate changes present urban planners with significant challenges, as traditional urban sewer systems are typically designed for the present climate. An easy and economically feasible way to mitigate this is to introduce a Sustainable Urban Drainage System (SUDS) in the urban area. However, the lack of knowledge about the geological and hydrogeological setting hampers the use of SUDS. In this study, 1315 ha of high-density electromagnetic (DUALEM-421S) data, detailed lithological soil descriptions of 614 boreholes, 153 infiltration tests and 250 in situ vane tests from 32 different sites in the Central Denmark Region were utilised to find quantitative and qualitative regional relationships between the resistivity and the lithology, the percolation rates and the undrained shear strength of cohesive soils at a depth of 1 meter below ground surface (m bgs). The qualitative tests enable a translation from resistivity to lithology as well as a translation from lithology to percolation rates with moderate to high certainty. The regional cut-off value separating sand-dominated deposits from clay-dominated deposits is found to be between 80 to 100 Ωm. The regional median percolation rates for sand and clay till is found to be 9.9 × 10−5 m/s and 2.6 × 10−5 m/s, respectively. The quantitative results derived from a simple linear regression analysis of resistivity and percolation rates and resistivity and undrained shear strength of cohesive soils are found to have a very weak relationship on a regional scale implying that in reality no meaningful relationships can be established. The regional qualitative results have been tested on a case study area. The case study illustrates that site-specific investigations are necessary when using geophysical mapping to directly estimate lithology, percolation rates and undrained shear strength of cohesive soils due to the differences in soil properties and the surrounding environment from site to site. This study further illustrates that geophysical mapping in combination with lithological descriptions, infiltration tests and groundwater levels yield the basis for the construction of detailed planning maps showing the most suitable locations for infiltration. These maps provide valuable information for city planners about which areas may preclude the establishment of infiltration-based SUDS.

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“…Knowledge of the hydrogeological setting in urban areas is crucial because it forms the basis for understanding the fate and distribution of the contaminants. In recent years, hydrogeophysical methods have become a valuable, non-invasive source of continuous data sections, significantly improving the data coverage and accuracy of the investigated urban areas (Bockhorn et al, 2015;Pazzi et al, 2016;Prudhomme et al, 2019). Geophysical methods have been applied at contaminated sites to identify fill materials and, in some cases, map contamination plumes (Boudreault et al, 2010;Maurya et al, 2017;Vaudelet et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Hydrogeological modelling to support urban planning in harbour areas: A case study from Horsens, Denmark

Cen

Medhus

Andersen

et al. 2021

Preprint

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Historically, industries were in harbour areas of cities for easy access to transportation of resources. Today, transforming former industrial areas into living spaces has become attractive business. However, this transformation has often been challenged by high levels of soil contamination caused by the industrial use. Remediation measures are mandatory to ensure the public safety in the redeveloped areas. Detailed information about the contaminant type, distribution and transport mechanisms is required to address the contamination issues. This paper presents a workflow for investigations assisting decision making for construction work in redeveloped industrial areas. The workflow is applied to Horsens harbour (Denmark). In this area, renovation of the harbour walls introduces the risk of spreading of phenol contamination to planned construction areas. The study demonstrates how detailed information about the geology and hydrology at the site allows for scenario modelling of contaminant transport, guiding remediation efforts and aiding decision makers in developing the harbour area.

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Geoelectrical mapping for improved performance of SUDS in clay tills

Cited by 5 publications

References 50 publications

Development of a high-resolution 3D geological model for landfill leachate risk assessment

Development of a high-resolution 3D geological model for landfill leachate risk assessment

Detailed Geophysical Mapping and Hydrogeological Characterisation of the Subsurface for Optimal Placement of Infiltration-Based Sustainable Urban Drainage Systems

Hydrogeological modelling to support urban planning in harbour areas: A case study from Horsens, Denmark

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