PhD studentship at the School of Earth Sciences, University of Leeds
funded via landfill tax credit scheme

Prediction of construction conditions in landfill cells using
geophysical surveys.

Closing date for applications: 1 July 2003

Many landfill sites in the UK are sited on glacial deposits, which are
composed of a series of sediment types including clays, sands and
gravels. The geometrical arrangement of these components, and the
overall thickness of the glacial sequence, is important for optimum
landfill cell siting, design, and selection of the best construction
method. In some previous cases, insufficient knowledge of the geological
conditions in glacial sequences has led to water ingress into landfill
cells, basal heave of the liner, flooding of the cell, and/or
instability of the side slopes. In particular, the presence of permeable
sand and gravel units has led to water ingress problems, where such
units provide hydraulic connection to the underlying aquifer. Prior
knowledge of the positions of sand and gravel units would greatly
facilitate cell depth selection and minimise risk of large unforeseen
costs arising from delays in construction due to flooding. A further,
separate advantage of more accurate and detailed site characterisation
is that it will aid in logistical planning where on-site material (i.e.
clay with specific properties) is used for construction of the mineral
liner.

The conventional approach to landfill site characterisation is based
around drilling boreholes and interpolating between these to produce
cross sections of the ground. Unfortunately, glacial sequences usually
contain sand bodies on the 5 to 50m scale that are often missed by this
approach. Geophysical methods such as resistivity imaging,
electromagnetic surveying, induced polarisation and shallow reflection
seismics have the potential to provide a great deal of information to
supplement that from boreholes.

The proposed study will use a mixture of established methods and recent
innovations from hydrogeological, glaciological and hydrocarbon
exploration, applied for the first time in the landfill environment.
Existing borehole data from will be combined with resistivity imaging,
electromagnetic mapping, induced polarisation, shallow reflection
seismics, geomorphological mapping, and comparison with modern glacial
systems to characterise glacial sequences at landfill sites where
further cell construction is planned. Soil samples will be taken using a
percussion drill and characterised for permeability. An understanding of
the three dimensional architecture of the glacial deposits will be
developed by identifying depositional processes and environments, using
knowledge of modern arctic glaciers and ice sheet margins. The
information collected by these methods will be combined to produce
conceptual geological models of the sites that will allow landfill cell
design to be optimised. The project will provide a series of published
case studies that illustrate best practise in the selection and
application of geophysical surveys to landfill siting.

Project Team

Dr Jared West is an engineering geologist with experience of using
resistivity and electromagnetic techniques to investigate
hydrogeological and geotechnical problems. He is familiar with the
issues involved in landfill siting and construction, including barrier
design, seepage analysis, and slope stability analysis. Tel: 0113
3435253 email: [log in to unmask]

Dr Tavi Murray is a glaciologist with 10 years of experience of using
geophysical techniques to investigate glaciers and their deposits. She
has also worked with Water Companies to apply geophysical techniques for
detecting pipe leakage.

Dr Roger Clark is a geophysicist with 20 years experience of using
shallow seismic techniques in near surface investigations for both
academic and industrial applications.

Contributing Third Party: A company of geotechnical or geophysical
consultants will be appointed to act as industrial supervisors. The
company concerned will have experience in use of conventional and
geophysical surveys to predict construction conditions at landfill sites

The student will probably be a geology or geophysics graduate will a
good first degree or MSc. He/she will join Leeds Hydrogeology Group,
which specialises in the application of geophysical techniques in
hydrogeology. Related research groups, such as the Glaciology and
Geophysics Groups will provide additional expertise. The student will be
trained using appropriate MSc level courses in hydrogeology, geophysics
and glaciology. On completion of the project this student will be well
placed for a career in hydrogeology, environmental geophysics or a
related discipline.


Note that full funding is available only to UK nationals and those of
other EU states. Application forms can be downloaded from following
website: http://www.leeds.ac.uk/rds/Admissions/Admis_home.htm
They should be submitted to the Postgraduate Secretary, School of Earth
Sciences, University of Leeds, Leeds LS2 9JT by 1 July 2003. Please
include references with your application. Please note that we expect to
hold interviews for this position on Wednesday 9th July.