Vanessa J. Banks

Anomalous buried hollows in London: development of a hazard susceptibility map

Engineering works carried out in central London over many decades have revealed a number of buried hollows that exhibit curious characteristics. Some extend deep into the bedrock geology and are in-filled with disturbed superficial deposits and reworked bedrock. Others are contained within the superficial deposits. They can be up to 500 m wide and more than 60 m in depth. As the infill material often has different behavioural characteristics from the surrounding deposits failure to identify them during an initial site investigation can prove costly. This paper considers their common characteristics and describes the method used to develop a buried hollow hazard susceptibility map. This map provides planners with a broader awareness of the potential location of difficult ground conditions associated with them, thereby reducing the potential for unforeseen ground conditions through effective site investigation design. The paper continues with a discussion of some of the likely processes associated with their formation, which are attributed to cryogenic processes, and concludes with potential future research directions.

Stratigraphical influences on the limestone hydrogeology of the Wye catchment, Derbyshire

Abstract Recent hydrogeological investigation of the catchment of the River Wye, Derbyshire (UK) has shown that published views of the local and regional hydrogeology lack sophistication. A conceptual model of the catchment hydrogeology has been formulated using the results of water tracing experiments, water chemistry and borehole hydrograph analyses, together with detailed consideration of bedrock lithology, geological structure and karstic process. The model highlights previously unrecognized differences in the hydrogeological behaviour of the distinct bedrock units. In conjunction with an assessment of the structural setting, the underlying stratigraphical differences assist in understanding the distribution, density and form of the springs in the catchment. A similar approach might assist understanding of the hydrogeology of other karstic aquifers.

The development of a GIS methodology to assess the potential for water resource contamination due to new development in the 2012 Olympic Park site, London

The Initial Screening Tool (IST) has been developed to enable Planners to assess the potential risk to ground and surface water due to remobilisation of contaminants by new developments. The IST is a custom built GIS application that improves upon previous screening tools developed by the British Geological Survey (BGS) through the inclusion of 3-D geological data and an enhanced scoring methodology. The key new feature of the IST is the ability to track individual pollutant linkages, from a source of contamination, along multiple possible Pathways to potentially susceptible Receptors. A rule based approach allows the methodology to be easily updated, and as a result the IST has a role in scenario planning. The application provides output in the form of an automatically generated report, in which details of the potential pollutant linkages identified are presented. The initial research area selected was the Olympic Park site, London.

Climate change: implications for engineering geology practice

Abstract The key questions addressed in this paper are: What is climate change? What are the impacts on engineering geology practice? Can engineering geologists contribute to mitigation of climate change? What research areas are engineering geologists involved with? Where should the focus for future research be? Following an overview of the papers presented for the ‘Legacy of the Past and Future Climate Change’ session of the 10th Congress of the International Association for Engineering Geology and the Environment, this paper reviews the sources of information and current models of climate change. An overview of some of the potential impacts of climate change on engineering geology practice follows. Attention has been given to areas of active research, the potential impacts on the more routine work of the engineering geologist, and the way in which the engineering geologist can contribute to climate change mitigation and adaptation. It is concluded that current planning guidance addresses climate change more fully than current engineering practice, and it is considered that there are considerable research areas open to engineering geologists with regard to potential impacts of climate change. More specifically, it has been noted that current engineering practice draws heavily on empirical approaches to design, and it is suggested that this approach should be reviewed in the context of climate change. Attention is given to a number of mitigating measures, such as ground source heat pumps, carbon sequestration, the ‘reduce, reuse and recycle’ approach to achieving sustainability and sustainable urban drainage systems (SUDSs).

Hydrogeological Significance of Secondary Terrestrial Carbonate Deposition in Karst Environments

proportion of the dissolved calcium carbonate derived from limestone dissolution. The study of such secondary deposits is important because they provide information on the palaeohydrogeology of the unsaturated zone at the time of precipitation. They also offer the potential to provide information with respect to climatic conditions through the study of stable isotopes and dating through the study of radiogenic isotopes. This chapter introduces the formational processes, depositional environments (hydrogeological, hydrogeochemical, biological and geomorphological) and post depositional history of secondary terrestrial carbonate deposits. Consideration is given to the associated research themes and techniques, in particular to the current research focus on the role of microbial communities in present day sediment-water interface processes (Pedley and Rogerson, 2010) and the implications for furthering the understanding of climate change and landscape evolution. These deposits have a world-wide distribution (Ford and Pedley, 1996; Viles and Goudie, 1990) and include speleothems, travertines, tufas, calcareous nodules, calcretes and carbonate cements, such that speleothems and tufa represent two end members of a continuum of freshwater carbonate (Pedley and Rogerson, 2010). They form in a range of climatic conditions, but are best developed in warm humid climates. Examples cited in the text include case studies from the White Peak, Derbyshire UK, which currently experiences a temperate humid climate and hosts a range of deposits as a consequence of its recent geological history. The White Peak was not subjected to glacial erosion during the most recent (Devensian, MIS 2-4) glaciation, therefore there is a potential for an extensive record of Quaternary palaeoclimatic conditions to be preserved in the secondary carbonate deposits.

Integration of Geohazards into Urban and Land-Use Planning. Towards a Landslide Directive. The EuroGeoSurveys Questionnaire

Exposure to hazards is expected to increase in Europe, due to rapid population growth in urban areas and the escalation of urbanization throughout many countries. In the framework of the European Geological Surveys (EGS), the Earth Observation and Geohazards Expert Group (EOEG) has carried out a survey based enquiry regarding the integration of geohazards (earthquakes, volcanoes, landslides, ground subsidence, floods and others) into urban and land-use planning. Responses from 19 European countries and 5 regions reveal heterogeneous policies across national borders. 17% of the countries have not yet implemented any legal measures to integrate geohazards into urban and land-use plans and half of the participating countries have no official methodological guides to construct geohazard maps. Additionally, there is a scarce knowledge about real social impacts of geohazards and resulting disasters in many of the countries, although they have a significant impact on their national economies. This overview stresses the need for a common legislative framework and homogenization of the national legislations as well as mutual guidelines which adopt the principles applicable to the management of geohazards and explain the process to be followed in the production of hazard documentation. This is especially relevant in case of landslide and subsidence hazards; although those are of great importance in Europe, there are no common guidelines and practices similar to Directive 2007/60/EC on the assessment and management of flood risk. Based on their expertise, EuroGeoSurveys (EGS) have the potential to coordinate this activity in European geohazard guidelines and to promote the interaction among stakeholders.

Superficial Hollows and Rockhead Anomalies in the London Basin, UK: Origins, Distribution and Risk Implications for Subsurface Infrastructure and Water Resources

Recent findings in London show that the subsurface is much more complex than expected, with a number of apparently anomalous features that present a direct hazard to infrastructure development and a risk to ground water management. Of these features, one of the least understood are the large superficial hollows which occur in the rockhead—in much of the London Basin, this is the top of the London Clay Formation—and which are infilled by a range of Quaternary deposits, principally alluvial sands and gravels deposited by the River Thames and its tributaries. The hollows range in size and shape. Several are a few hundred metres across and can be up to 40–50 m deep, though determining their exact form is problematic. The soil and sediment infill of the hollows differs substantially from the surrounding ground in terms of strength and drainage, as well as some differences in chemistry. This presents a real hazard to infrastructure as there is a potential for vertical and horizontal movement, flooding, as well as increasing the risk of contamination of the deeper aquifer. In the paper, the locations and characteristics of known hollows and deformed strata are reviewed and evidence for how they formed is reassessed, systematically considering different hypotheses (scour, ground ice, karst subsidence, seismo-tectonic). From this we consider the implications for continued development of subsurface infrastructure development, and for water resources.

A reassessment of the Brassington Formation (Miocene) of Derbyshire, UK and a review of related hypogene karst suffosion processes

The Brassington Formation of the Pennines is the most extensive onshore Miocene succession in the UK. It is preserved as outliers in Lower Carboniferous Limestone. During the Cenozoic, central England underwent uplift, with erosion of post-Mississippian strata from the Pennine axis in the Peak District. The Brassington Formation is hence significant in reconstructing Cenozoic geological history. It is non-marine, derived from Triassic sandstone and of Mid–Late Miocene age. The c. 60 outliers occur in three clusters over c. 220 km2. They are remnants of a sedimentary prism at least 75 m thick and with a volume of c. 10 km3. Suffosion of bedrock, conditioned by aggressive precursor fluids of hypogenic origin, was the major control on subsidence. The calculated volume of the fills in the Bees Nest and Green Clay outliers is 3.7–5.0 × 106 m3. Referenced to a sub-Miocene surface at c. 450 m OD in pre-subsidence times, the original volume of this subsidence complex was c. 21.8 × 106 m3 and the aggregated volume of the Late Neogene White Peak palaeokarst was at least 0.66 km3. Subsidence was concomitant with Pliocene uplift of the Pennine Axis, suggesting suffosion accommodation of 3 × 106 m3 per km2 or 244 m3 per annum.

Can sustainable development be achieved if geology is ignored

“Sustainable development” implies that a stable relationship between human activities and the natural world is possible such that the prospects of future generations do not diminish. Can this really be achieved in our urban centres where social and economic issues are often the driving force behind development? Geoscience information has traditionally been under-utilised in planning and development, because all too often its relevance and significance is misunderstood or underappreciated. However, this is starting to change. Using case studies from London and the Thames Gateway Development Zone, this paper discusses how technological developments, such as improvements in GIS technologies and 3D modelling software, are driving this turnaround. The paper also considers the impact of organisations not sharing ground investigation geodata and know-ledge about anomalous ground conditions across London, the huge benefits that data sharing can offer and how lessons learned in this study can be applied to other urban centres. The paper will show that within the environmental ecosystem, if one component part is misunderstood, then developing sustainably without compromising future needs will be difficult, if not impossible, to achieve. In London, difficult ground conditions cost developers time and money through project overruns and expensive engineering solutions. A more sustainable solution is in improving our understanding of the relationship between the geology (lithology) and its properties (physical, chemical or hydrological characteristics). We will show that for the urban underground to be fully utilised throughout Europe, the lack of development policies for the subsurface needs to be addressed. For a subsurface development policy to be written, stakeholders will need to regard the urban underground as environmentally sensitive, just as it does for the surface.