bluuebunny/crossref_metadata_2025 huggingface dataset:
The engineering geology of the Kielder Dam
Authors: Anderson J. G. C. , McNicol R.
Published: November 2007

Kielder Dam on the River North Tyne, northwest of Hexham in Northumberland, retains Kielder Water, an artificial lake impounded in 1982. The earth embankment dam and its associated concrete structures are founded on both drift deposits and rocks of the Scremerston Coal Group, a very mixed sedimentary succession of Lower Carboniferous (Dinantian) age affected by moderate folding and faulting. Aspects discussed include the staged site investigation for determination of construction materials, the stratigraphy and structure, the groundwater regime before and after dam construction, the relief well testing and the constructional geology. The latter is described in the form of a ‘guided tour’ through the dam foundations and covers, mapping, the recognition and treatment of adverse conditions arising from tectonic and glacially related processes of the past, reservoir impounding and its effects.
Groundwater sampling techniques for organic micropollutants: UK experience
Authors: Clark L. , Baxter K. M.
Published: November 2007

Sampling for organic micropollutants on a regional scale is from existing public supply or production boreholes. These give good samples for analysis but they will be of mixed waters and may not indicate the true occurrence of organic compounds in the groundwater. The most widely applicable groundwater sampling methods from open observation boreholes in the UK are based on submersible pumps. Several systems are now in use but all have drawbacks when used for organic micropollutant sampling. The present systems, particularly when used in conjunction with straddle-packers, are suitable for studies of inorganic groundwater quality or organic pollution at concentrations above about lmg1
-1
. There are increased difficulties, however, when sampling for trace organic contaminants below concentrations of 1μg1
-1
because of the ease of cross-contamination by the organic materials so prevalent in our environment. Great care has to be taken during sampling to minimize the cross-contamination.
Airborne multispectral scanning of subsidence caused by Permian gypsum dissolution at Ripon, North Yorkshire
Authors: Cooper A. H.
Published: November 2007

Around Ripon, North Yorkshire, catastrophic subsidence locally occurs because of natural underground dissolution in the Permian gypsum. This airborne study assesses the merits of multispectral scanning (MSS) as a method of detecting incipient subsidence areas and as an aid to geological mapping. The multispectral method indicates subsidence areas by vegetation, soil colour and temperature variations. Computer enhancement of the multispectral images allow some subsidence details not seen by conventional photography to be delineated. The MSS images are two-dimensional and even the most detailed ones have a fairly coarse resolution (1.5–2.0m). Because of this, conventional 3D interpretation of stereo air photographs better indicates the morphology of the subsidence hollows and the geology.
The 1985 Bairaman landslide dam and resulting debris flow, Papua New Guinea
Authors: King Jonathan , Loveday Ian , Schuster Robert L.
Published: November 2007

On 11 May 1985 a magnitude 7.1 (Richter scale) earthquake occurred on the island of New Britain, Papua New Guinea. The earthquake caused localized property damage and initiated widespread landsliding up to 30 km from the epicentre. One of the largest landslides, with an estimated volume of 180 x 10
6
m
3
, occurred in the narrow, steep-sided Bairaman River valley. This landslide started as a rockslide in weathered limestone and rapidly transformed into a debris avalanche, filling over 3 km of the Bairaman River valley to a maximum depth of 200 m and creating a landslide dam which impounded the Bairaman River. By August 1986 the resultant lake had attained a volume of about 50 x 10
6
m
3
and posed a grave threat to downstream inhabitants of the Bairaman valley. By September 1986 the lake was close to overtopping, the people were evacuated and the dam was breached. The failure of the dam took about 3 hours and generated a debris flow with an estimated volume of 120 x 10
6
m
3
and average velocity of 20 km h
-1
that travelled 39 km down the Bairaman valley to the Solomon Sea. At the river mouth the flood was 8 m above normal river level and swept away Bairaman village. Due to the evacuation no lives were lost.
The development of layered sediment beds in the laboratory as an illustration of possible field processes
Authors: Edge M. J. , Sills G. C.
Published: November 2007

Sediments laid down under water are frequently layered, the layers being identified by changes in particle size and/or density. The paper considers an example of such layering examined in a core from the Nares Abyssal Plain using an accurate, non-destructive X-ray technique for measuring density. It also reports a series of laboratory experiments in which a sediment containing sand, silt and clay-sized particles was introduced at a variable deposition rate into settling columns. The development of the bed was monitored using the same X-ray technique for density measurement, and the occurrence of layers, marked by changes in density and particle size distribution, is noted and discussed. It is suggested that a genuinely uniform naturally occurring sediment may well be quite uncommon.
Sea-level rise and coastal defences in the UK
Authors: Clayton K. M.
Published: November 2007

Although impossible to forecast accurately, it seems highly probable that sea level will rise by 200–400 mm over the next sixty years and the annual rate of rise will increase from 1–2 to 4–6 mm/year. The rise will present no new problems to coastal engineers but existing problems will be exacerbated, drawing further attention to the lack of a coordinated sea defence or coastal protection policy. Improvement requires a strategy involving planners and engineers in a concept of coastal zone management.
Softening of overconsolidated Cretaceous clays by glacial erosion
Authors: Sauer E. Karl , Gareau L. F. , Christiansen E. A.
Published: November 2007

Throughout southern Saskatchewan the upper part of unweathered Cretaceous clay is softened by glacial shear from an originally heavily overconsolidated state. Original preconsolidation pressures ranged from 10 000 to 13 000 kPa. Shear from glacial erosion created negative pore water pressures which caused an increase in water content and decrease in density. This also resulted in a reduction in apparent preconsolidation pressure. Depth profiles of water content for three sites were plotted against reference curves for the normally and overconsolidated states. From these plots the presence of softening is inferred. Softening was found at depths from 30 m to 143 m. Large blocks of intact overconsolidated clay separated by softened gouge zones as well as folds in the bedding structures have been interpreted as disturbance by glacial shear.
Hydrogeomorphic flood hazard evaluation for semi-arid environments
Authors: Kenny R.
Published: November 2007

On pediment, alluvial slopes and plains in semi-arid environments small washes constitute potential flood hazards. Population expansion into these geologically less suitable areas represents a major engineering concern. In this study, four flood hazard zones were identified based on the hydrogeomorphic analysis of an area in central Arizona, USA. The flood hazard zones depicted as map units provide a basis for flood management plans which are highly beneficial to engineers and urban planners. As they are based on common geomorphic indicators it is considered they are applicable to other semi-arid environments.
Degradation model for rock armour in coastal engineering
Authors: Latham J-P.
Published: November 2007

A degradation model specifically for rock armour in coastal structures is proposed. The objective is to give the coastal engineer a new design tool. The model provides a prediction of the armourstone weight loss with time on the structure. This information can help in the assessment of alternative design costings while taking account of the quality of rock from different possible sources.

Factors affecting the degradation rate are the intrinsic material properties of the rock source, the production-influenced geometric properties of the armourstone, the environmental boundary conditions at the coastal site and the armour layer design concepts used. To apply the model to a given rock source, a sample of the material is tested in an abrasion mill simulation of the wear process. This gives a weight versus laboratory time plot. Laboratory time is converted to years on site using an equivalent wear time factor which is derived from a combination of nine weighted parameters. The effects of the other principal degradation mechanisms, fracturing and spalling, are included as well as abrasion. For example by using parameter estimates which couple meteorological climatic conditions with particular rock type susceptibilities, the influence of physico-chemical degradation can be assessed.
The problem of quality control and selection of armourstone
Authors: Clark A. R. , Palmer J. S.
Published: November 2007

The successful use of naturally occurring rock as an armourstone depends on the selection of suitable material which will perform the function for which it was designed.

Two recent case histories of coast protection works with a combined total of about 200 000 tonnes of rock armour demonstrates that adequate quality and selection control procedures were not utilized and as a result substantial quantities of rock were rejected, and in one case costly arbitration procedures were involved. In each case the contractor for the works was responsible for the provision of armourstone in compliance with the specification and had simple engineering geological controls been used substantial savings could have been made.
Behaviour of radon in the geological environment: a review
Authors: Ball T. K. , Cameron D. G. , Colman T. B. , Roberts P. D.
Published: November 2007

A review of the behaviour of radon in the geological environment is presented. The general geochemistry of the element is described and the factors controlling its emanation from minerals and rocks and into the disperse phases itemized. A brief summary of analytical procedures for the analysis of the radon isotopes in waters and soil gases is given. The emanation of radon depends upon the source term uranium concentration, the nature of the host mineralogy, the permeability of the host rock and soil and the characteristics of the transporting medium. Weather can have a profound effect upon the concentration of radon in soil gas but often the variation due to the geological substrate is greater. Radon is not a problem unless it collects in buildings and underground structures. Some guidelines are given for identifying areas of high radon emanation based upon existing data sets.
An introduction to geological aspects of methane occurrence and control in British deep coal mines
Authors: Creedy D. P.
Published: November 2007

Practical methods for measuring the in situ gas contents of coal seams, modelling seam gas content trends, determining rates of methane emission from strata disturbed by mining and assessing the likelihood of unusual emissions are outlined. The constraints imposed by methane on coal production are highlighted and attention drawn to its attendant hazards. Successful planning for the control and exploitation of colliery methane cannot be achieved without a sound knowledge and understanding of the geology with which the mine interacts.
The expression of faults in UK seismic hazard assessment
Authors: Mallard D. J. , Woo G.
Published: November 2007

Earthquakes occur in Britain and faults move, yet traditionally little consideration has been given to active faulting in UK seismic hazard assessment. Increasingly, digital micro-seismic data and geological neotectonic investigations are beginning to identify active faults. Hence, procedures have been developed for incorporating specific faults within calculations of the probability of exceedance of ground motion and ground rupture. Using these procedures, scoping calculations are presented which illuminate the potential impact of active faults on these hazards.
Fault detection using soil gas geochemistry
Authors: Duddridge G. A. , Grainger P. , Durrance E. M.
Published: November 2007

Soil gas surveys have been carried out at research sites in Great Britain and Italy to test soil gas geochemistry as a site investigation technique for the detection of faults and discontinuities. At a site on Oxford Clay in Gloucestershire, soil gas anomalies of high He, Rn and CO
2
and low O
2
were shown to correspond to the outcrop of a fault, identified by drilling and geophysics. Other apparently random anomalies remained unexplained and lateral migration of gas through superficial horizons complicated interpretation. Using three parallel sample lines at the same distance apart as the sample spacing it has proved not only possible statistically to remove spurious anomalies, but also to enhance and concentrate clusters of high values resulting from gas migration.

This method was used to investigate a fault in Neogene clay at Narni in Italy where a gas pathway permeable to Rn and CO
2
was identified, corresponding to a geoelectrical anomaly indicating displaced strata. Further work was carried out over a fault revealed by trenching in the Caithness Flags in Scotland. For each three-line traverse an integrated gas anomaly map was produced to aid interpretation by allowing both sharp and diffuse anomalies to be more easily identified.
Geophysical investigations of photolineaments in southeast Zimbabwe
Authors: Carruthers R. M. , Greenbaum D. , Peart R. J. , Herbert R.
Published: November 2007

The paper presents preliminary results of continuing studies in SE Zimbabwe aimed at understanding the role of fracturing in hard rock aquifers. This is a semi-arid region in which a high proportion of boreholes drilled for water supply are dry or provide minimal yields for hand-pump usage. Remote sensing, using satellite images and aerial photographs, provides a rapid means of identifying potential fracture systems but field evidence of the nature and precise location of such fractures is limited. Ground geophysical techniques such as resistivity, electromagnetic and magnetic surveying have been extensively tested over a few selected sites in an attempt to characterize their response where photolineaments occur. These data reveal the presence of anomalies, predominantly of shallow origin, some of which correspond with the lineaments. Initial results suggest that the lineaments studied do not represent major, open groundwater conduits. Drilling and borehole logging information confirms the view that fracturing is poorly developed in general. An interpretation of pump test data collected as part of hydraulic fracturing tests suggests that drilling itself results in the preferential opening of vertical fissures near the borehole but that background transmissivity is very low. The work is continuing with a programme of core drilling and cross-hole seismic tomography, the results of which will be incorporated in further modelling of the geophysical data.
Engineering description of mudrocks
Authors: Hawkins A. B. , Pinches G. M.
Published: November 2007

The term ‘mudrock’ is used to describe all non-metamorphic argillaceous deposits. A three-fold classification of mudrocks is proposed: siltstone comprising less than 25% clay fraction, claystone containing more than 40% clay fraction and mudstone restricted to the intermediate materials. ‘Metamud-rock’ is used to describe weakly metamorphosed argillaceous rocks whose strength and geomechanical behaviour has been affected by the albeit limited re-crystallization.

The paper provides clarification of the terms rock material weathering, rock mass weathering, weathering grades and weathering zones, lithorelicts and apparent lithorelicts. The criteria separating moderately and highly weathered rock are reviewed and, for mudrocks, a recommendation made that in engineering geological descriptions the boundary should be amended to 200f the material having soil characteristics rather than 50%. The term ‘completely weathered’ should be replaced by ‘extremely weathered’.

A consistent word order for soil and rock descriptions is advocated, beginning with the material strength. Recommendations are made to resolve the present ambiguities in the use of ‘to/and’ in strength descriptions. An aide memoire for the identification, description and field assessment of strength of argillaceous rocks is provided.
Aeolian sand hazards and engineering design for desert regions
Authors: Stipho A. S.
Published: November 2007

In hot climate zones of the Middle East region, the soil is generally unconsolidated, the unprotected surface sediments being continuously mobilized by the moderate to high velocity wind characteristic of the area. Movement of sand dunes, ground surface erosion and accumulation of dust clouds not only challenge civil engineering practice but seriously affect the lives and environs of the people as far as protection, economic and agricultural growths are concerned.

Special measures to combat the hazardous impact of moving sand within engineering design and project development are discussed. Attention is drawn to the limited quantity of data available and the importance of anticipating sand movement. The paper reports both actual field measurements and the procedure followed to obtain information on the sand movement pattern at a particular site. The data were used successfully to generate a pattern of sand movement and to estimate maintenance work and the quantity/quality of sand.
Field techniques and instrumentation in shallow seismic reflection
Authors: Hill Ian A.
Published: November 2007

The essential criteria which determine the effectiveness of a shallow seismic reflection survey are its resolution and its sensitivity. The factors involved in the choice of equipment and field technique are reviewed with respect to these two primary objectives.

The analysis is developed from a consideration of the energy phases produced by a seismic source and the way desirable phases can be isolated and enhanced by single-channel and multi-channel recording. Specifications for the instrumentation and the field techniques can then be derived to satisfy the requirements of the processing methods. The primary considerations are (1) to preserve the maximum possible frequency content and bandwidth in the recorded data to enhance resolution, and (2) to suppress source-generated noise energy which is the principal limit on sensitivity.
Imaging a buried river channel in an intertidal area of South Wales using high-resolution seismic techniques
Authors: Brabham P. J. , McDonald R. J.
Published: November 2007

A buried river channel in an intertidal area at Barry Old Harbour, South Wales, UK, is investigated using high-resolution seismic refraction and reflection techniques. The refraction technique is able to profile the base of the 20m deep buried valley because the Carboniferous Limestone bedrock has a significant velocity contrast with overlying water-saturated unconsolidated sediments.

Common midpoint (CMP) reflection profiling, using a single detonator as the seismic source, images the base of the river channel and the internal sedimentary sequences. Seismic reflections with frequencies in the 400 to 600 Hz range are observed from as shallow as 5 m depth (6 ms two-way time).

The bedrock profiles derived from the refraction and reflection experiments are in precise agreement.
A computer program for ground investigation data storage, manipulation and presentation
Authors: Deans I. A. , Morley R. S. , Howland A. F.
Published: November 2007

The development of a geotechnical data handling, storage and presentation program is described. The system has demonstrated its capability on a major ground investigation contract and is currently being further developed to enhance its capabilities. Use of the system will reduce the time spent by relatively expensive engineering staff on routine plotting tasks and allow them to use large data sets more fully prior to selection of design parameters.
Hydro-thermo-mechanical properties of joints in the Carnmenellis granite
Authors: Zhao J. , Brown E. T.
Published: November 2007

Hydro-thermo-mechanical tests on joints in the Carnmenellis granite from Cornwall, southwest England, were carried out using a geothermal rock test facility. Both natural joints and artificial fractures were tested at effective normal stresses up to 40 MPa, differential pore pressures to 6 MPa and temperatures to 200°C. Experimental effective normal stress-joint closure and effective normal stress-joint permeability data were fitted by a range of deformation and hydraulic models. Difficulties were encountered in finding single values of material and geometrical constants that applied to the complete range of data and samples. The joint condition factor (JCF) is introduced as a factor to account for deviation from the ideal conditions assumed in the smooth parallel plate theory. The experimental results show that the value of JCF depends on a combination of joint surface geometrical characteristics. Initial apertures increased with a rise in sample temperature depending on the joint surface geometrical properties. An empirical logarithmic relation between initial aperture, temperature and joint roughness coefficient (JRC) is proposed.
A procedure for assessing compositional uniformity of sand and gravel aggregates for concrete
Authors: Sims Ian , Miglio Bruno
Published: November 2007

Modern assessments of the suitability of aggregates for concrete frequently include the petrographical examination of a single set of samples taken from stockpiles at a particular time. This study has shown that a structured petrographical study (SPS) carried out over a period of production gives a more reliable representation of the aggregate composition and can also be used to provide reassurance about the probable future uniformity of the material. Two flint-dominated sand and gravel sources in regular operation were selected: one sea-dredged and the other land-based. Sets of processed coarse and fine aggregate samples were taken monthly during a year of continuous exploitation and supply. The samples were each subjected to quantitative petrographical examination in accordance with the draft British Standard procedure. The results have been evaluated and indicate for these samples a higher degree of compositional uniformity over a period of production than might have been anticipated from a preliminary geological consideration of the source deposits. In both cases, the main constituents repetitively occurred, but the relative proportions varied within limits. In this single comparison of one sea-dredged source with one land-based source, the sea-dredged aggregate was marginally the less variable material. The practical application of SPS is illustrated with regard to the control of flint or chert content in aggregate combinations.
The use of down-hole focused electric logs to investigate saline groundwaters
Authors: Brassington F. C. , Lucey P. A. , Peacock A. J.
Published: November 2007

During the course of a hydrogeological investigation into saline groundwater problems in a Permo-Triassic Sandstone aquifer in northwest England, an opportunity was taken to obtain focused electric logs in 12 fully penetrating coal exploration boreholes. These logs provided data of a type not usually available in a water industry groundwater investigation because of expensive drilling costs. The data have been used to examine highly mineralized groundwaters which are situated near the base of the aquifer. The technique provides information on the conductivity of both fresh and saline groundwaters, the depth at which conductivity increases and the thickness of the diffusion zone. Comparison of focused electric logs produced in mud-filled boreholes with the more usual hydrogeological technique of conductivity logs in open boreholes shows that focused-electric logs more accurately reflect field conditions.
Structural and geomorphological aspects of the Çatak landslide,NE Turkey
Authors: Genc S.
Published: November 2007

The bedrock of the Çatak area comprises Upper Cretaceous marls, shales, tuffites, limestone and basalts. This is overlain by younger colluvium, essentially loose material detached from the bedrock masses by chemical, mechanical and/or tectonic processes where older rocks crop out. The bedrock is slightly folded but highly fractured. The geological and the geomorphological field investigations have shown that jointing and faulting in combination with pervasive weathering, steep topography, water incision, heavy rainfall and road cuts have all played a significant role in the occurrence of the landslide.
On an occurrence of abnormal acidity in granular soils
Authors: Sandover B. R. , Norbury D. R.
Published: November 2007

As part of a site investigation in the late 1980s for the construction of a new road, a large number of pH and sulphate determinations were made with two thirds of samples having measured pH of less than 5.5 and one result as low as 2.3. The implications for the design of buried concrete and pipework are significant. As there was some doubt whether these values represented in situ conditions, a further programme of field and laboratory testing involving both standard and non-standard test methods was carried out. This confirmed that the low values measured in the original investigation were misleading.
Prediction of water levels in an abandoned granite quarry in Singapore
Authors: Zhao J.
Published: November 2007

A hydrogeological case study at the abandoned Hindhede Granite Quarry examined groundwater seepage, water balance, rate of water level change and attempted to predict the final water level in the quarry. In August 1996, the water level in the quarry was at about +14 m MSL, while the general ground-water level in the vicinity was at about +25 m MSL. The present water level in the quarry pit is increasing at about 3.5 m/year. It will decrease gradually in future years. The water level will reach the rock head at +35 m MSL in 6 to 12 years depending on the prevailing climatic conditions.
Introduction
Authors: Charman J. H.
Published: November 2007

The Glossop Lecture has been initiated as the most prestigious lecture of the Engineering Group of the Geological Society, to be presented by an invited eminent engineering geologist. The requirement for the presentation is that it should highlight the contribution made in the application of engineering geology to civil engineering. This may be achieved by utilizing a subject that illustrates a particular expertise or summarizes a significant contribution to the science by the invitee. Alternatively, the speaker may choose to highlight a significant case history.

I am delighted that our first Glossop lecturer is Professor Peter Fookes, an engineering geologist who I am sure needs little introduction to the majority of you. The committee had little difficulty in agreeing that he was the most appropriate, indeed the outstanding choice. His breadth of experience is phenomenal and so tonight you will be privileged to hear what is effectively an overview of geology and engineering. What could be better suited to the first of our Glossop lectures?

Peter began his career as a soil chemistry technician in the 1950s before gaining his first degree in geology at Queen Mary College, London. During this time he developed an interest in engineering and after graduation he secured a job as a field geologist with Binnie, Deacon and Gourley, now Binnie, Black and Veitch, in West Pakistan working on the Mangla Dam. He started and completed an external PhD on the engineering characteristics of Siwalik Clays under the supervision of Professor A. W. Skempton. At
Petrographic and engineering properties of sandstones from the Sneinton Formation, Nottinghamshire, England
Authors: Bell F. G. , Culshaw M. G.
Published: November 2007

The Sneinton Formation occurs at the base of the Mercia Mudstone Group and consists of sandstones with interbedded siltstones and mudstones. The sample material was obtained from core from a 63 m deep borehole sunk near Epperstone some 10 km north of Nottingham. The petrographic characteristics, namely quartz content, clay size content, packing density and particle size distribution of the sandstones, were determined for a series of depths. In addition, the density, porosity, compressive and indirect tensile strengths, hardness, modulus of deformation, Poisson's ratio and slake durability index were determined for the same depth intervals. The petrographic characteristics then were correlated with the physical and mechanical properties and the significance of the relationships assessed by Student's
t
value. The individual physical and mechanical properties also were the correlated with each other and the significance of the relationships similarly assessed.
Joint monitoring on a rock face bearing an historical bas-relief
Authors: Košták B. , Dobrev N. , Zika P. , Ivanov P.
Published: November 2007

Preservation of a historical bas-relief on a high rock face in a seismically active area in NE Bulgaria called for stability investigations including joint monitoring. Engineering geological investigations revealed structures liable to creep within the bedrock including joint deformations registered in spatial three components and angular deviations between joint faces. A distinct relationship between joint movement and individual earthquakes has been found and changes in deformation character have occurred in periods of increased seismicity. Temperature variations, and notably frost effects have been found to affect shallow joints. The paper describes a case in which relatively inexpensive monitoring has been successful in terms of interpretation of results.
Assessing the significant factors in a rock weathering system
Authors: Hill S. E. , Rosenbaum M. S.
Published: November 2007

The processes operating within a rock weathering system may be described qualitatively in the form of an interaction matrix, comprising those factors which are considered significant in the system and the mechanisms operating between them. A method of assigning site-specific values to the significant factors is developed, enabling a quantitative analysis of the effects of weathering on the rock mass. Applying an integer code to the interactions enables the individual factors' influence within the system to be assessed. An index for weathering may be derived from this analysis and used, in conjunction with an index for engineering geological properties, to characterize and zone a weathered rock mass.
Dewatering the Thanet Beds in SE London: three case histories
Authors: Linney L. F. , Withers A. D.
Published: November 2007

The construction of the Jubilee Line Extension in southeast London required the construction of a number of deep excavations extending into the Thanet Beds. These Lower Tertiary strata are predominantly silty fine sands, and in order for the excavations to be carried out in the dry, dewatering was necessary. Three examples of excavations in the Thanet Beds are described in this paper, in each of which dewatering was attempted by pumping from the underlying Chalk to induce drainage of the Thanets. Although the three sites were only approximately 1 km apart, the performance of the dewatering schemes was different at each site. One excavation proved impossible to dewater by this method, whilst the other two, although successfully completed, demonstrate very clearly the extreme variations in the permeability of the Chalk and the difficulties that may arise therefrom.
Dewatering and environmental monitoring for the extractive industry
Authors: Streetly M.
Published: November 2007

In the current climate of environmental protection, environmental monitoring data often play a crucial role in the planning process leading to the extraction of minerals from open excavations. Yet often the relatively modest capital and human resource commitments required to operate an effective monitoring network in the early stages of development are allowed to obscure the real long-term benefits of collecting high-quality data. In this paper the pressures facing those responsible for commissioning environmental monitoring networks are set out. Common problems faced are described, along with the consequences of inadequate monitoring. The economic value of good data is emphasized and ways in which this can be achieved are summarized with particular emphasis on the need for regular reviews of incoming data.
The use of recharge trenches to maintain groundwater levels
Authors: Cliff M. I. , Smart P. C.
Published: November 2007

Dewatering mineral workings may have an adverse impact on the water table in the surrounding area. Although dewatering for mineral extraction purposes is exempt from licensing under the Water Resources Act 1991, it may be controlled by conditions included in planning consents. Two sites are described where the planning authority has imposed conditions relating to groundwater control and recharge trenches have been constructed. The first is a site in the Midlands adjacent to a Site of Special Scientific Interest (SSSI) where the flora and fauna are dependent on a high water table. The second is a site close to a wetland area in West Yorkshire.
The hydrogeological effect of quarrying karstified limestone: options for prediction and mitigation
Authors: Hobbs S. L. , Gunn J.
Published: November 2007

The hydrogeological effect of limestone extraction from open pits (quarries) depends on the location of the site in the landscape, the vertical and horizontal extent of the excavation, the methods used to excavate the stone, and the extent of karstification. Groundwater quality is commonly affected by quarrying through increased fine sediment concentrations and accidental spillages. Removal of any soil cover allows direct access for pollutants into the aquifer, a problem which may be exacerbated by licensed or illegal tipping of waste following cessation of stone extraction. Quarrying also removes the entire subcutaneous (epikarstic) zone which is an important ground-water store, together with part or all of the unsaturated zone. Pumping of water from the excavation will change the ground-water balance and can alter the direction and amounts of conduit flow, particularly if the quarry extends beneath the water table. Prediction of such impacts is difficult, especially when the limestone is karstified, such that there will always be a degree of uncertainty associated with the impact of the workings. Hence, it is essential that for new quarries monitoring is undertaken prior to, throughout, and following mineral working, with options for mitigation if mineral working causes an unacceptable impact. When a quarry ceases to be worked, the direct impacts on groundwater quality may rapidly decrease but there are important implications for after-use of the site. Impacts on groundwater quantity are likely to be more long-term.
A study on the accuracy of sand and gravel reserve estimates
Authors: Wardrop D. R.
Published: November 2007

Little work has been published that compares actual yields from sand and gravel excavations with reserve calculations based on drilling. To do so sites must meet criteria of clear identification; in-house site investigation; full drilling; and properly recorded production. There are several potential sources of difference between calculated and actual figures.

Twenty-six sites were investigated, yielding from 63.64% to 152.400f calculated reserves. The mean of the results is 104.37%, the median 104.31% and the mode group 107.0–109%. This analysis confirms that, in a majority of cases, the measurement of reserves using conventional techniques is accurately carried out. A variance of ± 5 0s suggested as the geologist's target.
Decrease in the CBR of a gypsiferous soil due to long-term soaking
Authors: Razouki S. S. , El-Janabi O. A.
Published: November 2007

The effect of long-term soaking on the California Bearing Ratio (CBR) of compacted gypsiferous soil containing about 64 0ypsum was studied. Sixteen CBR samples compacted at optimum moisture content and 950f the modified AASHTO dry density were prepared in accordance with ASTM (D 1883-87). Two samples each were soaked for periods of 0, 4, 7, 15, 30, 60, 120, and 180 days with a 20 lb (89 N) surcharge load. The water in the soaking tank was changed continuously to avoid full saturation with gypsum. The tests revealed a sharp drop in CBR with soaking period, especially within the first week. Thereafter, the loss in CBR took place at a smaller rate so that the soil strength became constant after about six months. The decrease of total soluble salt and gypsum content in soil with increasing soaking period is in full agreement with the loss in CBR with soaking period. The paper reveals that a soaking period of four days can lead to serious overestimation of soil strength for these soils.
Core density scanning, degree of induration and dynamic elastic moduli of Palaeogene limestone in the Copenhagen area
Authors: Henriksen Anton D. , Fabricius Ida L. , Borre Mai K. , Korsbech Uffe , Theilgaard Anja T. , Zandbergen Julie B.
Published: November 2007

Density scanning by gamma transmission measurements on whole cores is here demonstrated to be valuable both as a sampling guide in the core laboratory, and for assessing the degree of induration of Palaeogene limestones in Denmark. Fracture intensity is also indicated. Moduli of elasticity calculated from acoustic velocities are systematically related to density (and thus porosity), so we have attempted to relate the degree of induration to the dynamic moduli of elasticity. The dynamic moduli of elasticity fall, as is commonly observed, above those measured from uniaxial compression tests. P-wave as well as S-wave velocities are anisotropic in the entire porosity interval (12%–44%). This is reflected in a significant anisotropy of the dynamic shear modulus at high densities, whereas the anisotropy for lower densities and for the dynamic Young's modulus and dynamic bulk modulus remain below the level of significance. The anisotropy probably reflects minor horizontal fractures formed during exhumation of the limestone and unloading of the cores. The density scanning tool thus proves a useful method for determination of geophysical and geotechnical parameters.
Geophysical investigation of unsaturated zone transport in the Chalk in Yorkshire
Authors: Zaidman M. D. , Middleton R. T. , West L. J. , Binley A. M.
Published: November 2007

Electrical resistivity imaging of field-scale solute transport in the unsaturated zone of the Chalk in East Yorkshire is described. The study involved application of an electrically conductive tracer to the surface of an 18 m
2
plot at a rate of 49 mmd
-1
for two days (representative of very heavy rainfall). The resistivity response of the upper 25 m over the following ten months is reported. These results are interpreted together with geological and hydrological data. The hydrogeological interpretation is that rapid bypass flow occurs along steeply inclined joints during high intensity rainfall in autumn and winter, but not usually during the summer. Joint saturation occurs locally, progressing upwards from horizons rich in thin marl layers.
Characteristics of some rainfall-induced landslides on natural slopes, Lantau Island, Hong Kong
Authors: Franks C. A. M.
Published: November 2007

The north part of Lantau Island is undergoing rapid development following construction of the new airport at Chek Lap Kok. This development, primarily on reclaimed land, is adjacent to a range of steeply sloping hills that experience levels of annual rain in excess of 2500 mm. Rainfall induced landslides on this steeply sloping natural terrain are potential hazards to developments down slope. Landslides on these natural slopes resulting from two major rainstorms in 1992 and 1993 were studied to determine their characteristics and define the geomorphological factors influencing their debris trails. These data were compared with the aerial photographic record of landslide scars within the same catchment over the period 1945-1995 to determine the potential hazard from natural terrain landslides to downslope development.

The limited data set indicates that channelized debris flows which produce long debris trails pose the greatest hazard potential to downslope development. Factors influencing debris flow paths and deposition zones were assessed from a geomorphological study of the catchment to define criteria for preliminary hazard zoning of downslope developments.
Competency assessment of two clay soils from South Wales for landfill liner contaminant attenuation
Authors: Yong R. N. , Tan B. K. , Bentley S. P. , Thomas H. R.
Published: November 2007

This study focuses on the basic test and evaluation requirements necessary for a successful competency assessment of the contaminant attenuation capability of clay soils. Two clay soils from South Wales were chosen for study. Of particular interest is the problem of specification of ‘
necessary and sufficient tests
’ for proper assessments of competency. The tests and evaluation protocols leading towards confident competency assessment of the candidate clay soils are developed. Soil column leaching studies, together with results from analyses of the physicochemical and mineralogical characteristics of the soils, are used to determine clay soil contaminant attenuation capability. The results demonstrate that reliance on a limited amount of information can lead to some inappropriate premature interpretations that can prove to be harmful. In a situation where attenuation of dissolved metals is important, only one of the soils tested is considered to be an adequate clay soil for a clay engineered barrier.
Weathering and regolith properties at an earthflow site
Authors: Trotter Craig M.
Published: November 2007

The influence of weathering on the physical, chemical and geotechnical characteristics of soils has been examined for both unstable and adjacent stable ground at a site in North Island New Zealand where earthflows have developed in regolith overlying Tertiary calcareous mudrock of marine origin. The same sequence of weathering zones was visually identified during sample extrusion for both the unstable and stable ground, although the earthflow sites were characterized by extension of weathering to greater depths. Both the characteristics of the weathering zones and the relationships between calcite content and geotechnical index properties show significant similarities to those reported for the Fuller's Earth in the UK. Variations in density and moisture content throughout the profiles are attributed to variations in the extent of stress relief fissuring, augmented by a calcite content which varies with depth and position on the slope. If the variation in dry density (and moisture content) due to calcite content alone is removed, the depth at which stress relief fissuring becomes prominent can be readily discerned and appears to be associated with the zone of basal shear in the earthflows. Physico-chemical swelling appears to be absent, even though the soil mineralogy is dominated by Casmectites. Post-failure weathering, clay mineral alteration and calcite removal are expected to provide a mechanism for promoting gradually increasing earthflow instability.
Defining a borehole capture zone in a complex sandstone aquifer: a modelling case study from Shropshire, UK
Authors: Papatolios K. T. , Lerner D. N.
Published: November 2007

The sandstone aquifer in eastern Shropshire in central England is being extensively used for public water supply. However, rising nitrate concentrations in boreholes in the unconfined parts of the aquifer are a cause for concern. Edgmond Bridge, a new major abstraction, has recently been put into service. This study examines the hydrogeology of the sandstone aquifer in the area and uses a three-dimensional numerical groundwater flow model to represent the aquifer and to define the Edgmond Bridge borehole catchment and distribution of flows within it. For an abstraction rate of 12 500m
3
/d the catchment occupies an area of 18.7km
2
and is fed by direct and valley side recharge, induced river infiltration and lateral groundwater inflow.
Editorial
Authors: West Graham
Published: November 2007

With this number of the Quarterly Journal of Engineering Geology we have a change of Editor. Dr Brian Hawkins of Bristol University, who has been the Scientific Editor of the Journal since 1987, is standing down and I will undertake this responsibility until Dr John Cripps of Sheffield University can take over the Editorship in June 1994.

During his period of office, Dr Hawkins maintained the high standards of the Journal and was responsible for a number of successful initiatives, among which were the Young Authors' Awards and the policy of encouraging papers from abroad. On behalf of the Society and the readership I would like to thank Dr Hawkins for his fine service as QJEG Editor.

The scope of the QJEG is well set out on the inside front cover of every number, but I would like to say a few words here of a more philosophical nature about the purpose of the Journal. This is to provide engineering geologists and hydrogeologists with the very best scientific papers on all aspects of engineering geology and hydrogeology, be they the results of field or laboratory research, case history studies, state-of-the-art reviews, Working Party reports or technical notes. Because the Journal sets out to be an international journal, care will continue to be taken to include papers from overseas authors and on overseas topics as well as from those in the UK. In this way, the pages of the QJEG will record the most recent advances in both the theory and
Crown hole development in the sandstone caves of Nottingham
Authors: Waltham A. C.
Published: November 2007

The Nottingham caves have been artificially excavated in the Triassic sandstone. Some of their unsupported roofs, spanning up to 5 m, exhibit progressive collapse which can develop into crown holes. Nearly all recorded roof failures have occurred where and when the rock has become saturated by water from rainfall or pipe leakages. Saturation causes the sandstone to lose rapidly about half its strength as a consequence of the breakdown of clay bridges between the sand grains.
Mining-induced seismicity in the Nottinghamshire Coalfield
Authors: Bishop I. , Styles P. , Allen M.
Published: November 2007

Between July 1989 and August 1990 over 130 earth tremors were felt and reported by people living in the Edwinstowe district of Nottinghamshire. In order to determine whether the tremors were caused by mining activity, a small aperture array of eight temporary surface seismometer stations was established around the area of coal extraction from Thoresby Colliery. Over the following l 1-month period, 785 micro seismic events were detected. The spatial and temporal patterns of this seismicity can clearly be seen to be associated with the commencement, the continuing extraction and the closure of faces. Activity is at a minimum at weekends, holidays and during periods of enforced closure due to the weather, rising to a maximum on the Wednesday of each week. Events occur within days of a face going into full production and cease at the end of the production, with good correlation between face advancement and hypocentral position. While the location of events outside of the array is inferior to those within the Thoresby take, it is clear that there are very strong indications that the majority of these events originate from the adjacent collieries, especially Welbeck, Ollerton and Clipstone. While the results establish a definite causal relationship between coal production and the local microseismicity, frequency magnitude studies suggest that the seismic hazard and risk of damage to properties is low, as the maximum magnitude recorded during this period was less than 2.5.