bluuebunny/crossref_metadata_2025 huggingface dataset:
Rockfall checkfences at Pen-y-Clip on the A55 North Wales Coast Road, UK
Authors: Nichol Douglas
Published: November 2007

The A55 North Wales Coast Road between Chester and Holyhead forms a strategic part of Euroroute E22 (Sassnitz to Dublin) and provides a major artery to the British and European motorway network for traffic arising not only from North Wales but also from Ireland via the international ferry terminal at Holyhead (Fig. 1). The highway comprises 145km of modern dual carriageway. Unfortunately rockfall activity poses a significant geohazard in the vicinity of the mountainous headland at Pen-y-Clip and especially affects the westbound carriageway approaches to the road tunnel through the headland (Fig. 2). This area has a history of high rockfall frequency and, in 1984, a rock avalanche blocked the headland road and caused a two week closure (McWilliam 1991). At Pen-y-Clip, steep slopes and adverse geological factors combine to create potentially unsafe ground above the road.

The Pen-y-Clip promontory constitutes a natural obstacle along the coastal plain and routes tend to converge towards the seaward point of the headland. The Pen-y-Clip road tunnel, opened to traffic in October 1993, was driven through the headland and a wide variety of rockfall protection measures including rockfall checkfences were incorporated into the design and construction of the project (Brady et al. 1994). The checkfences were installed in advance of construction to protect the workers on the scheme and to safeguard the headland road particularly against rockfall initiated by blasting during construction.

Geologically, the headland at Pen-y-Clip comprises a core of igneous rocks associated with the Penmaenmawr intrusion (Fig. 3). The intrusion measures
Modelling the evolution of minewater pollution at Polkemmet Colliery, Almond catchment, Scotland
Authors: Chen M. , Soulsby C. , Younger P. L.
Published: November 2007

Polluted discharges from abandoned mines are a major cause of freshwater pollution in central Scotland, often contributing high Fe, SO
4
2-
and acidity to receiving streams. The Central coalfield has been extensively mined for over a century and Polkemmet was the last colliery to close in 1985. Recent monitoring indicates that the rate of groundwater recovery is approximately 0.15 to 0.2 m per week. Without intervention, this trend would result in complete recovery by 2000 and probable discharge into the River Almond. Geochemical modelling indicates that pyrite oxidation, calcite dissolution and goethite precipitation are primarily responsible for the evolution of groundwater chemistry currently observed at Polkemmet. Predictive modelling using PHREEQE suggests that unregulated minewater discharges will have marked effects in the River Almond, with goethite being initially precipitated at a rate of up to 36 kg/day, dissolved sulphate concentrations ranging between 170 and 800 mg/l and pH being depressed to 6.5. Combined active lime flocculation and passive aerobic wetlands may be the most effective means of treating the predicted minewater discharges. Keywords: abandoned mines, hydrochemistry, surface water, underground mining, water quality
Crag aquifer characteristics and water balance for the Thurne catchment, northeast Norfolk
Authors: Holman I. P. , Hiscock K. M. , Chroston P. N.
Published: November 2007

A study of the hydrogeological controls on the Pleistocene Crag aquifer in northeast Norfolk is reported. Geophysical methods, in particular multichannel seismic reflection profiling, have provided useful information on the internal structure of the aquifer. The Crag represents a layered aquifer, with horizons of clay and silt strata able to limit the overall vertical permeability of the aquifer. A laterally continuous clay horizon is identified at around -25 mOD and is mapped as far as the coast. Shallow wells and borehotes in the Crag are prone to contamination. Nitrate is widely recorded, with concentrations of typically up to 150 mg l
-1
in shallow wells, derived from mainly agricultural sources, although deeper boreholes are less affected given the restricted downward movement of ground-water. The land drainage systems within this lowland area dominate the hydrology and hydrogeology of the catchment. Surface flows into the River Thurne are controlled by the operation of drainage pumps and a catchment water balance demonstrates that groundwater principally discharges to the drainage ditches within the extensive arable and grazing marshes in the catchment.
Hydrogeology and European legislation
Authors: Sheils A. K.
Published: November 2007

The paper distinguishes between the definitions of ground water in the UK and in European Community (EC) law. Each of the three main EC directives affecting groundwater is considered in turn, together with the associated official circulars. Examples are given of some problems of interpretation of the EC Groundwater Directive.

Details are included of a new national classification scheme for dangerous substances reaching groundwater. Threshold values are set out in a formal 'direction' for the criteria of low toxicity, persistence, and bioaccumulation.

Recent and possible EC developments relating to ground water are also indicated. For example a Ministerial Seminar held at The Hague in late 1991 proposed an action programme to be prepared by the EC Commission by mid 1993 and to be implemented by 2000; the setting up of international expert groups and possible moves towards harmonizing the monitoring of groundwater.

New European legislation for the protection of ground water may be expected within the next few years. However, further EC action is likely to depend on more general questions relating to the role of the Community.
High-purity limestones in England and Wales
Authors: Harrison David J.
Published: November 2007

Most limestone is used in the construction industry principally as an aggregate and in the manufacture of cement. A high degree of chemical purity in these limestones is not usually necessary although some restrictions on contaminants may be made. Around 10 million tonnes of limestones are used annually for industrial purposes which require ‘high-purity’ limestone or limestones of specific physical properties which are, at least to some extent, related to the purity of the limestone. Such limestones are used in the iron and steel industry, in the chemicals industry, in glass making, in fillers and pigments and in a wide range of other industries. An increasingly important use of ‘high-purity’ limestone is in flue gas desulphurization schemes in power generation plants.

This paper describes the broad geological resources of high-purity limestone in England and Wales. Most high-purity deposits occur within the Carboniferous Limestone of the Peak District, the Mendips, South and North Wales, parts of the northern Pennines and around the fringes of the Lake District. Large areas of the Chalk outcrop also contain high-purity resources, particularly part of the Upper Chalk outcrop of southern England and in the Burnham and Welton chalk outcrops of northern England. The dolomites and dolomitic limestones of the Permian Magnesian Limestone also locally contain consistently pure deposits. Jurassic, Devonian and Silurian limestones are mainly of low chemical grade.
Hydrogeological studies on the Rock of Gibraltar
Authors: Wright E. P. , Rose E. P. F. , Perez M.
Published: November 2007

The hydrogeology of an aquifer within the dolomite/limestone formation that dominates the Gibraltar peninsula has been studied with a view to the possible development of contained groundwater resources taht occur as a thin lens of fresh water overlying sea water. Recharge rates (calculated by soil moisture and chloride balance) could be of the order of 400 000 m
3
per year. This is significant in relation to the current demand for potable water of some 1 000 000 m
3
per year, 900f which is provided by desalination. Exploration drilling focused on fracture zones, but tested vertical boreholes generally demonstrated a rapid decline in water quality, even where drawdowns were very small. Exploration also revealed oil pollution of the groundwater within the Rock, most significantly near the Naval Dockyards to the soutwest and less so beneath the North Face. The greatest potential for sustained discharge was found to occur in shallowly inclined boreholes. Discharge quality was clearly sensitive to a range of factors including immediate rainfall events, tidal fluctuations, vertical permeability of the aquifer, borehole design and anthropogenic effects. Further studies are needed to determine the significance of these controls and to assess whether development of the likely resources is practicable.
Editorial
Authors: West Graham
Published: November 2007

Among the recurring suggestions listed in the responses to the 1993 membership survey undertaken by the Society, was the request for a higher profile for hydrogeology, and the inclusion of environmental geology. Hydrogeology has always featured in the QJEG (a paper on groundwater in Tehran appeared as early as Volume 1, Part 3) but the journal has not published in the environmental geology field before. We feel, however, that there is considerable potential for publications in both fields, and it has been decided that, as there are a number of excellent hydrogeological papers awaiting publication at the moment, a special Hydrogeological thematic part will be issued alongside Part 3 of the QJEG this year at no extra cost to subscribers. In addition, it is proposed to include environmental geology and waste management within the scope of the journal from now on. Readers of the QJEG can help this exciting new development by spreading the word that papers on the engineering geological or hydrogeological aspects of environmental protection and waste management can now be considered for publication.

Construction materials have always been of interest and concern to engineering geologists and this has been reflected in the pages of the QJEG from its inception. As early as Volume 1, No. 2, we had a seminal paper on the polishing of roadstones that described a test that is still in use today and which, over a quarter of a century, has contributed greatly to road safety in many countries. Construction materials continue to
Geotechnical characterization of blended coal tailings for construction and rehabilitation work
Authors: Indraratna B.
Published: November 2007

Coarse and fine refuse is produced by various coal processing equipment. For instance, fine tailings (100-500µm) are produced by froth flotation cells, whereas coarse fractions (up to 50 mm) constitute cyclone rejects. The relatively wet fine tailings have limited use in construction activities and they are generally pumped as slurries into tailings ponds. The coarse rejects have a greater engineering applicability and are utilized in the construction of tailings dams, mine access roads as well as for landfill and ballast. This study investigates the fundamental engineering properties of blended tailings, where- by appropriate fractions of flotation tailings are mixed with cyclone rejects to produce an acceptable construction or rehabilitation fill. In particular, a practical procedure to optimize the blended ratios is proposed on the basis of fundamental geotechnical testing. The applications of relevant tests are described, including Proctor compaction, California Bearing Ratios, triaxial and consolidation tests. The results confirm that blending of fines with coarse rejects enables enhanced dry densities associated with reduced permeabilities, higher shear and compressive strengths, lower consolidation settlements and increased bearing capacities. The addition of a small quantity of cement (2-5%) further improves the engineering properties of the blended matrix. The practical findings of this study should encourage coal processing plants to modify their existing disposal methods to adopt more efficient co-disposal schemes. Optimization of procedures for discarding fine and coarse rejects together would generate substantial savings, with regard to dewatering of wet tailings and rehandling of distinctly different waste gradations.
Discussion on ‘Analysis of residual subsidence movements in the UK coalfields’
Authors: Yao X. L. , Reddish D. J.
Published: November 2007

N. R. Goulty writes: Yao & Reddish published an empirical formula for the duration of mining subsidence in months,
t
, expressed as a linear function of the mining depth in metres,
h
, and the percentage of hard rock in the overburden,
p
:

t
= 1.5553 + 0.0321h + 0.037
p
. (1)

They presented a nomograph based on this formula,which they recommended as a tool for civil engineers to calculate the time span after which no precautions need be taken to protect surface buildings from further damage due to residual subsidence.

The observations used to find (1) are shown in Fig. 10 and Table 2 of Yao & Reddish's paper. There were a total of twelve observations of residual subsidence at known depths, but the percentage of hard rock in the overburden was only known in nine cases. They first found the line of regression for
t
on
h
, using all twelve observations:

t
= 3.1854 + 0.0321
h
. (2)

Then, in the nine cases for which
p
was known, they found the line of regression for the residuals, Δ
t
, between observed values of
t
and those predicted from (2), on
p
:

Δ
t
= - 1.6301 + 0.037
p
. (3)

Finally, they combined (2) and (3) to produce (1). This procedure may appear to be attractive in the absence of a complete dataset, but in fact it is not statistically rigorous and results in a prediction function which is not optimum.

Generalized matrix inversion produces the best solution, in the least-squares sense, for the
Moisture retention characteristics of coastal sabkhas
Authors: Sabtan A. , Al-Saify M. , Kazi A.
Published: November 2007

Water plays an important role in governing the properties and behaviour of engineering soils. The amount of water a soil can retain depends not only on the nature of soil, including its mineral composition, texture and structure, but also on the type and concentration of the salts dissolved in the water. In this experimental study, samples of a siliciclastic aeolian soil are mixed separately with different concentrations of salt water. The mixing waters used in these experiments are representative of the groundwaters encountered in different types of sabkhas occurring near the coastal town of Dahban in the Kingdom of Saudi Arabia. A number of graphs are prepared to display relationships between the salinity of the mixing water and the amount of water that is retained by the soil at different temperatures. In general, the higher the salinity of the groundwater, the greater is the amount of water retained by the sabkha. For the same drying temperature, the rate of moisture decrease diminishes with time. The maximum rate of moisture decrease is experienced by the soil mixed with the least concentrated salt solution.
Seismic hazard mapping of Jordan
Authors: Malkawi Abdallah I. Husein , Al-Homoud Azm S. , Liang Robert Y.
Published: November 2007

Earthquake hazard maps for Jordan are presented in this paper. These maps show the peak ground acceleration (PGA) on bedrock and modified MercaUi intensity (MMI), both with 907fb3e69crobability of not being exceeded during a period of 50, 100 and 200 years. The probabilistic PGA and MMI values are calculated based on the line source model in the computer program FRISK (McGuire 1978). The line sources in Jordan and the vicinity are identified to include nine distinctive seismic sources. The pertinent parameters of each line source, such as the
b
-parameter in the Gutenberg-Richter formula, the annual rate λ4 and the upper bound magnitude
m
1
, are determined from two sets of seismic data: the historical earthquake records and the instrumentally recorded earthquake data (1900–1991). The seismic hazard maps are intended for preliminary analysis of new designs and seismic check of existing civil engineering structures.
Weathering and weathering processes
Authors: Price D. G.
Published: November 2007

Definitions of weathering are examined and a definition of weathering for geotechnical purposes is proposed. Weathering is achieved by weathering processes, which depend upon the nature of the new environment to which the geological materials are introduced. Weathering processes are reviewed with particular reference to examples from engineering practice. The weathering product, the modified geological material and mass, is a consequence of the interaction of the weathering processes and the geological materials and mass on which the weathering processes act. Modes of weathering of particular rock types are reviewed. The paper concludes with a discussion of classification policy, recommending simplification.
Description and classification of weathered rocks for engineering purposes: the background to the BS5930:1981 proposals
Authors: Dearman W. R.
Published: November 2007

With the impending publication of the first revision of BS5930:1981 it is pertinent to set down the background to the simple statements made for the descriptive terms proposed for the weathering of rock material and the scale of weathering grades of the rock mass. The seminal accounts published in the 1950s related to the weathering of granite at engineering sites in the Snowy Mountains, Australia, by Moye, and a scientific account of the weathering of granite in Hong Kong by Ruxton and Berry. Fifteen years later, these early accounts provided the basis for two Geological Society Engineering Group Working Party Reports in 1970 and 1972 as guides to good site investigation practice. A statement on the weathered state of a rock, or engineering soil, comprised only one element of a scheme of description in which the rock name was prefixed by selected descriptive terms of the rock in the hand specimen as a material and in the mass, with suffixes used to indicate the main engineering properties, one of which was the estimated mechanical Strength of the rock material. Because a similar descriptive scheme was adopted for BS5930:1981, it was felt appropriate at that stage to omit any reference to strength in the proposed scale of weathering grades of the rock mass and the descriptive terms for the weathering of rock material. However, the strength criterion was dealt with separately in the full engineering description.

This change was part of a growing dissatisfaction with some aspects of the earlier descriptive schemes for rocks. After publication of BS5930:1981, the descriptive scheme for weath- ering was later criticized as being too restricted in scope and not easily applicable to a wide range of rock types and structural situations, although this was the original intention. As a basis for discussion, a reversion to Australian experience was proposed using a much simplified classification. The proposal envisaged four so-called condition-terms combined with descriptive terms for rock material strength, closely parallel to the original Moye classification of weathered granite material. This scheme holds out the prospect of application to a wide range of rock types in varying structural conditions.
Drakensberg basalts: their alteration, breakdown and durability
Authors: Haskins D. R. , Bell F. G.
Published: November 2007

The basalts of the Drakensberg Formation consist of a succession of lava flows which total some 1400m in thickness. Many of the lava flows are characterized by amygdaloidal zones. Many of the primary minerals within the basalts have been subjected to varying degrees of deuteric alteration which has led to the formation of clay, and chlorite and zeolite to a lesser extent. Some interstitial glass has also broken down to form clay. These secondary minerals, together with zeolites which occur notably as amygdaloidal fillings, mean that many of the basalts break down rapidly on exposure. The breakdown results principally from the expansion which occurs when the clay minerals swell on absorption of water. This gives rise to crazing.

The mineral content of the basalts was determined by modal analysis and X-ray diffraction. In addition, methylene blue adsorption was used to estimate the clay content. The secondary mineral rating was determined primarily from the modal analyses. Soak tests and free swell tests using ethylene glycol and water; water absorption, wet and dry, and freeze- thaw tests were carded out to assess the durability of these basalts. The olivine basalts and those types which contained disseminated clay spots were the least durable, some breaking down rapidly on testing. This was caused mainly by the expansion of clay minerals. Water absorption was also influenced by the presence of zeolites, notably laumontite. Another factor which has to be taken into account in relation to break down and durability is texture since this can restrict access of water to swelling minerals.
Textural and microstructural influences on the durability of Waikato Coal Measures mudrocks
Authors: Moon Vicki G. , Beattie A. G.
Published: November 2007

Data on durability, petrography and microstructure are presented for 27 specimens of Waikato Coal Measures mudrocks: fine-grained, carbonaceous rocks, which are dominated by kaolinite clays, and have low durabilities. The poor durability is not caused by swelling clays. Rather, slaking is believed to result from the release of residual stresses within the rock following weakening by water adsorption on to clay surfaces and a consequent loss in cohesiveness. This mechanism favours fragmentation into small, water-stable fragments, rather than dispersion of clays into the water. The amount of day-sized material in the rocks provides the most direct control on the durability, but mierostructural features are also recognized as important: specimens with a discontinuous matrix have a slightly lower durability than those with a continuous matrix.
The destruction of Sodom and Gomorrah: a geotechnical perspective
Authors: Harris G. M. , Beardow A. P.
Published: November 2007

This paper examines the geotechnical background to the destruction of the cities of Sodom and Gomorrah as described in the Book of Genesis. The paper inter-relates structural geology, geotechnical properties of near-surface sediments and seismicity with aspects of bitumen production and water supply. Conclusions suggest that the legendary Vale of Siddim was located to the northeast of the Lisan Peninsula at the southern extremity of the present-day North Basin of the Dead Sea. The destruction of the cities was the consequence of a seismic event leading to liquefaction of the alluvial plain constituting the Vale of Siddim. The event thus represents the first liquefaction event in recorded Judaeo-Christian history. The cities of Sodom and Gomorrah were lost beneath the waters of the North Basin as a consequence.

The paper illustrates the contribution of geology and engineering to a study of historical interest.
The misclassification matrix: a tool for validating geotechnical data
Authors: Nathanail C. P. , Rosenbaum M. S.
Published: November 2007

The misclassification matrix offers a powerful way to establish how reliable are the measurements of a geotechnical property and how well defined are the categories in a classification scheme. Using soil strength in a case history, poor agreement was generally observed between the field description of soil consistency and the undrained shear strength as measured in quick undrained triaxial tests on ‘undisturbed’ samples. A misclassification matrix was used to show the disparity between description and measurement. Errors in the description of strength may have accounted for discrepancies of one class but not of two and three classes. This suggests that the sampling process tended to result in weakening probably due to stress relief and sample disturbance effects.
The long-term weathering of PFA and implications for groundwater pollution
Authors: Lee S. , Spears D. A.
Published: November 2007

Borehole samples of weathered PFA were taken from an ash disposal mound at a major British power station. The oldest ash studied was deposited in 1975. XRD and SEM investigation of weathered PFA showed no substantial changes in mineralogy, such as the formation of secondary clay minerals, as the result of weathering. However, element concentrations in porewater and PFA varied as a function of depth indicating (a) reaction of PFA with infiltrating porewaters and attainment of equilibrium (Ca, SO4
2-
, Ba, St), (b) reaction without attainment of equilibrium (Mg, Na, K, B, Mo) and (c) elements infiltrating into the PFA from the surface (Cl
-
, NO
3
-
). The depth trends were used to assess mobility and migration of elements in the PFA mound and thus to produce information on leachate evolution in older PFA disposal sites in which leachates could either enter surface waters or pass downwards into groundwater.
Evaluation of alluvial aquifers for small-scale irrigation in part of the southern Sahel, West Africa
Authors: Hazell J. R. T. , Barker M.
Published: November 2007

Aquifers in the sand alluvium of the broad riverine flats (fadama) of the southern Sahel and northern Sudan climatic zones of West Africa are a major source of water for irrigation essential to crops in bad years. Annual recharge is from rivers flowing seasonally into the Sahel from the wetter south. Landforms which evolved in the mid Tertiary control the modern drainage. From the Pleistocene onwards rivers vigorously eroded the crystalline highlands of the Jos and Air massifs and carried the coarse alluvium far downstream. The resulting aquifers are often several kilometres wide and mostly over ten metres thick, sometimes much thicker, and are capped by late Pleistocene loessic soils. Aquifer properties are typical of the mostly coarse unconsolidated sands. The alluvial groundwater is reached and abstracted by methods appropriate in scale to family size farms. The system of farming and irrigating is socially beneficial and economically viable. The paper concludes with case studies of three rivers of Bauchi State in Nigeria. The alluvial aquifers are evaluated and related to irrigation potential, expressed as the percentage of land which may be irrigated using only the groundwater beneath it.
Regional trends in matrix porosity and dry density of the Chalk of England
Authors: Bloomfield J. P. , Brewerton L. J. , Allen D. J.
Published: November 2007

Laboratory measurements of porosity and dry density are presented for 2045 core samples from the Chalk of England. The data are subdivided on the basis of gross stratigraphy, i.e. Lower, Middle and Upper Chalk, and into four geographical areas: Northern England, East Anglia, Thames & Chilterns and Southern England. Statistical analysis of the data shows (i) that the porosity distributions for the Upper Chalk of the Southern and Thames & Chilterns regions are indistinguishable, (ii0 that the porosity distributions for the middle and Lower Chalk of the East Anglian region are indistinguishable, and (iii) that the porosity distributions for each of the gross stratigraphical units from all other regions are statistically discrete. Porosities range from 3.3% to 55.5%, with a mean porosity of 34.0%. Dry densities range from 1210 kg/m
3
to 2510 kg/m
3
, with a mean dry density of 1790 kg/m
3
. In a given region there is a trend of increasing porosity from Lower to Middle to Upper Chalk. There are systematic variations in porosity between the regions. There is a trend of increasing porosity from the Northern England region to the Southern England region, to the Thames & Chilterns region, to East Anglia. No significant systematic variations in porosity-depth gradients were observed. Chalk porosity-depth gradients are typically high, of the order of -0.07 to -0.1 porosity per cent per metre.
Ground motion amplification: an example from the city of Tangshan, China
Authors: Forster A. , Jackson P. D. , Li Xianzhong
Published: November 2007

The city of Tangshan lies on the edge of the North China Tangshan Fault in the east (Fig. 1). Movement on the Plain, south of the Yanshan mountain range in north Tangshan fault was the cause of the 1976 earthquake. eastern China (Fig. 1). It also lies at the centre of what The greater part of the city is underlain by thick was probably the most devastating earthquake in alluvial deposits which comprise various combinations recorded history. On 28 July 1976 the city was almost of clay, silt, sand and gravel. These superficial deposits totally destroyed by an earthquake of magnitude 7.8 cover an irregular bedrock topography of Ordovician whose epicentre lay almost exactly below its centre. The limestone and Permo-carboniferous sandstone, shale total number of deaths will never be known but it was and coal. A series of hills of weathered and eroded undoubtedly of the order of 240 000 (Chen-Yong
et al
. bedrock are present in the central and northern districts 1988) and may have been as high as 650 000 (Jennings of the city where they have been uplifted between the 1980). The number of those injured was about 700 000. Tangshan and Dou He River Faults.

The Tangshan region lies at the intersection of two A major effort was made to reconstruct the city after fault systems, the east—west trending Yinshan—Yanshan the earthquake and this included taking into account belt and the north-northeast trending Ji-Liu fault block engineering geological factors in the reconstruction system which consists
Rapid failures of colliery spoil heaps in the South Wales Coalfield
Authors: Siddle H. J. , Wright M. D. , Hutchinson J. N.
Published: November 2007

The exploitation of the South Wales Coalfield, particularly from the last quarter of the nineteenth century onward, was accompanied by numerous instances of instability within spoil heaps and their foundation materials. Sudden failures which were sufficiently rapid to overwhelm property and services and, in some instances, to threaten life, occurred on at least twenty three occasions, details of which are provided. It is believed that thesel included sixteen flow slides, five debris slides and two failures caused by outbursts of groundwater. At five sites, debris flow was a secondary failure mechanism. The locations of these failures are mostly clustered in those parts of the coalfield with the highest relief and with the highest rainfall, although antecedent rainfall conditions for the failures were variable. Most are shown to be associated with active tipping faces, but one flow slide is believed to have occurred on a tip four years after its abandonment and an outburst failure on a tip fifteen years old. The occurrence of rapid failures is shown to mirror the development of the coalfield but has ceased largely as a result of legislation to improve tipping practice, which was enacted following the Aberfan flow slide.
The engineering properties and behaviour of the brickearth of south Essex
Authors: Northmore K. J. , Bell F. G. , Culshaw M. G.
Published: November 2007

Brickearth occurs in south Essex where it overlies Quaternary terrace gravels and London Clay of Eocene age. In places it is as much as 8 m in thickness. Quartz is the most abundant mineral and feldspar occurred in most specimens examined. Of the clay type minerals, mica is generally more abundant than mont- morillonite which, in turn, is more abundant than kaolinite. Calcium carbonate occurs as grains, concretionary nodules and thin tube fillings.

The moisture content normally varies between 12 and 25% and the soils are of low to high plasticity. Clayey, silty and sandy brickearths are recognized, with most belonging to the silty variety. They are uniform to well sorted with most samples having a positive skewness. The porosity of the brickearths is around 40% with a mean dry density of 1.68 Mg/m
3
.

Brickearth can have a collapsible fabric. In the case of the brickearths from south Essex this was assessed in terms of collapse indices and the oedometer test. About half the samples tested in the oedometer were metastable. As would be expected, the degree of compressibility of these brickearths is high.

The undrained shear strength of these brickearths showed that they ranged from very soft to very stiff. There is a general tendency for shear strength to decrease with depth as the soil near the ground surface has a ‘crust-like’ nature.
Hydraulic pulse testing of single fractures in porous and deformable hard rocks
Authors: Rutqvist Johnny
Published: November 2007

Single borehole pulse injection tests were carried out on single natural fractures in granitic rocks at a depth of 80 to 417 metres to determine the hydraulic aperture. Pressure pulses were created by injecting a small volume of water into the fracture using a compressed-air driven downhole valve. The pulses were of short duration with a fast pressure decay and apertures as small as a few microns could be measured. The field tests were modelled with a finite element program which simulates coupled fluid flow and mechanical deformation in both the fracture and the ambient rock matrix. The results of modelling show that if fracture flow dominates, then the storativity is dominated by the mechanical deformation of the fracture. For the short duration pulse tests used in this study, the deformation of the fracture and thus the storativity is restricted by the stiffness of the ambient rock. The results of the modelling indicated that the fracture storativity is close to 3.5 x 10
8
. Field tests in hard rocks can therefore be evaluated with conventional curve matching methods using an assumed storativity to determine flow dimension and transmissivity. The known storativity makes the determination of hydraulic aperture of the fracture less subjective.
The influence of joint-planes on the mass strength of Hong Kong saprolitic soils
Authors: Au S. W. C.
Published: November 2007

Saprolitic soils containing relict joint-planes are common throughout Hong Kong in areas of
in situ
weathering of granites and volcanic rocks. A series of shear box tests on both the joints and the matrix soil of sarolitic soils is reported. The results reaffirm that the shear strength of the relict joints is much lower than that of the matrix soil, though the difference may diminish as decomposition advances. Relict joint-planes cannot therefore be ignored in assessing the mass strength for slope design in saprolitic soils, especially in the relatively less decomposed zones.
Naturally fractured rock mass quality zonation in Saudi Arabia
Authors: Sadagah Bahaaeldin H. , Sen Zekai
Published: November 2007

The intensity of joints varies spatially throughout any rock mass, therefore the description of the whole rock mass quality by a single conventional rock quality designation(RQD) value is rather insufficient.In practice, the rock mass quality changes along any line through a rock mass depending on the direction of measurement. A new statistical method is proposed for expressing rock quality data which involves deriving an empirical RQD distribution from scanline data. The method is demonstrated with reference to three different quality rock masses in Saudi Arabia. The distribution can be used in the assessment of the level of risk entailed in adopting a particular single design value of RQD.
Regional gas geochemistry in an active tectonic zone, Erzurum Basin, eastern Turkey
Authors: Salih Bayraktutan, M. , Merefield, J. R. , Grainger, P. , Evans, B. M. , Yilmaz M. , Kalkan E.
Published: November 2007

The Karasu Plain is an intermontane sedimentary basin with a Miocene—Quaternary volcanicbasement, andesitic-basalticlava flows and fissure eruptions of basaltic lava. It was filled in the early Quaternary by lacustrine fan-delta deposits, and later by fluvial-alluvial fan deposits. The basin is characterized by NNE-SSW trending sinistral wrench faults on its eastern margin and ENE-WSW trending reverse faults on its southern margin. Both systems of active faults intersect very near to Erzurum, which is considered to be the most likely site for the epicentre of a probable future large earthquake. Regional gas geochemistry has therefore been undertaken adjacent to the city of Erzurum, in order to characterize radon levels over the varied lithologies, examine the potential for geological fault mapping and assess the status of fault activity. Initially,41 sites were sampled and analysed for Rn, CO
2
, O
2
and CH
4
in soils along three traverses to the east (8.26km and 4.5km length) and to the west (6.8km length) of Erzurum. During the first investigation, 495 Rn determinations were made from 165 samples at 41 sites over a ten-day period, during which a small earthquake (M=2.95) occurred. Another 211 sites have been subsequently used for Rn investigations including one traverse through the centre of the city. Additionally,water samples were degassed for Rn and soils tested at five key sites around the Erzurum Plain. Radon was readily detected in soils at all sites. Both
222
Rn and
220
Rn were present at most. Soils over major lithologies gave characteristic signals and, in all traverses, anomalously high values coincided with active faults. Little correlation was found between spring gases (thermal and cold) and adjacent soils. De-gassed spring water Rn values proved highest along the southern margin of the basin and CO
2
values were highest along the northern edge.
Behaviour of an artificially replenished shingle beach at Hayling Island, UK
Authors: Whitcombe L. J.
Published: November 2007

Many coastal areas throughout the world are suffering from erosion, so numerous attempts are made, by constructing various forms of sea defences, to stabilize a retreating beach or reduce its rate of erosion. In recent years, artificial beach replenishment has become an established method in helping to restore a deteriorating beach. However, there has been a relative lack of information regarding the post-replenishment behaviour of many artificially renourished beaches. Results of a study of a replenished beach at Hayling Island suggest that the apparent depositional and erosional trends measured along a typical beach profile can be due to the longshore movement of a single, trapezium-shaped, mass of shingle, at a constant rate, rather than variations in the longshore transport rate.
Modelling groundwater flow in the Sellafield area
Authors: Heathcote J. A. , Jones M. A. , Herbert A. W.
Published: November 2007

This paper presents a snapshot of how numerical modelling of groundwater is being used in the interpretation of hydrogeological data for the proposed Sellafield radioactive waste repository. The main objective of the modelling at the present stage of the investigation is to help develop a conceptual understanding of the site hydrogeology, by testing whether particular concepts are quantitatively feasible and whether they are able to explain observations.

Models have been constructed with differing levels of detail: they each contribute to building a consistent conceptual model of the behaviour of the site as a whole, but they do not individually provide such an integrated conceptual model. They are presented here to illustrate the approach to developing the conceptual understanding, and to illustrate the range of quantitative approaches being applied to different aspects of the site hydrogeology.

Four groups of models are described in outline, incorporating variously porous medium and fracture flow, complex geology, anisotropic formations, and dense solutes from more than one source. These are modelled in two and three dimensions.

A two-dimensional areal model reproduces head variation observed in shallow wells penetrating the Sherwood Sandstone Group, identifying recharge and discharge areas, and constraining the hydraulic conductivity of the sandstone. Vertical section models through the geological sequence, incorporating one or two sources of dense saline water were able to reproduce qualitatively the main features observed in deep boreholes, in terms of pressure and salinity. The two-source model produces the better match to the salinity distribution.

A three-dimensional model, using simplified geology, was able to demonstrate the interaction of salinity and geology, and demonstrate how pressures and salinity may evolve with time. Three-dimensional fracture network models of the Borrowdale Volcanic Group show head variability with depth similar to that observed in some deep boreholes. A number of fracture concepts and parameter distributions are compatible with the data. The modelling work presented shows progress towards a numerically consistent conceptual hydrogeological model of the Sellafield region that can accommodate the site characterization data, and further work is under way to continue this progress.
Slope instability in historic hilltop towns of Basilicata, southern Italy
Authors: Gostelow T. P. , Del Prete M. , Simoni A.
Published: November 2007

The importance of preserving Italian hilltop towns through a general geotechnical strategy is discussed and is followed by a specificreview of the hydrogeologicalconditions responsible for regional mass movements at ancient hilltop towns in Basilicata. A historical survey of reactivations in colluvial deposits at selected sitesin the region suggested that increased activity was taking place in response to extreme rainfall events, possibly related to long-term climatic changes. The importance of natural and anthropogenic processes along critical hydrogeological boundary conditions in relation to this activity is then reviewed and one example of urban landsliding from Grassano in the Basento valley is described. Local structure, such as faulting, was shown to be especially important in the location of both groundwater discharge (springs) and the landsliding. The landslide activity in the town was also shown to be related to a period of population expansion and possible domestic water leakages following the provision of a pumped supply. It is suggested that these anthropogenic processes reduce the usefulness of empirical links between landslide frequency, rainfall extremes or other explanations involving climatic change. Finally, a strategy for landslide management based on the use of hydrogeological conceptual models and GIS technology is proposed.
Tectonically influenced glacial erosion, and ensuing valley infill: a geophysical survey
Authors: Taylor W. P. , Wilson C. D. V.
Published: November 2007

A geophysical survey has been made of the buried floor and infill of the Gilpin-Kent Valley, south Cumbria. The 18 km valley has been investigated using 50 seismic refraction spreads and 140 gravity stations. The survey has been integrated with data from boreholes and with the adjoining Morecambe Bay Barrage feasibility survey.

Five geophysical cross-sections of the valley are given, together with one from a former site investigation near Arnside. Maximum depth to bedrock on each profile lies between 40 and 90 m. The rock floor is dissected by faulting into segments of Silurian and Dinantian (Carboniferous) strata; the softer Silurian rocks have been preferentially eroded to form subglacial tunnel valleys with relief of up to 40 m. In the south the strike of the Carboniferous beds and the trend of some of the faults swing from north-south into a NE-SW direction, which governs the course of the River Kent to its mouth at Grange-over-Sands.

The valley fill consists mostly of silty clay, with some peat; beneath the clay is a horizon of gravel/cobbles that is up to 40 m thick in some of the tunnel valleys. Till has not been recognized in the survey; the gravel may be its reworked remains. The deep and irregular rock floor of the valley points to a glacial regime of vigorous erosion, both by ice and by melt water.

Geotechnical data from boreholes have been correlated, where possible, with seismic velocities and density.
Drainage characteristics of a cut soil slope with horizontal drains
Authors: Whiteside P. G. D.
Published: November 2007

Groundwater in a regraded, previously unstable slope was controlled by installation of a parallel array of horizontal drains. During a major rainstorm, the discharge from these drains was measured continuously over a period of 65 hours. The results showed that groundwater flow was taking place preferentially along highly permeable subsurface drainage paths and that the overall piezometric level was being controlled by the drains. The characteristics of the drainage curve indicate that some drainage paths only operate at times of high flow.
Corrosion Performance of Stainless Steel and Inconel in Simulated Fuel-Cell Media
Authors: Rivas Sandra V. , Cuara Edgar , Manriquez Federico , Terol Ivan , Orozco Germán
Published: November 2007

In a Proton Exchange Membrane Fuel Cell (PEMFC), the bipolar plates are exposed to oxidant conditions on one side and reducing conditions on the other. The requirement of good electrical and thermal conductivity, good corrosion resistance, low weight, a good impermeability to the reactant gases and low cost restricts the choices of materials to manufacture bipolar plates. The objective of this research is to determine the corrosion resistance of candidate bipolar plate materials in the chemical environment encountered in PEM fuel cells. Several austenitic stainless steels (SS304 and SS316) and nickel alloys have been examined (Inconel 600, Inconel 601, Inconel 625, Incoloy 800H). The out-of-stack tests involved two types of electrochemical measurements, made in solutions that simulate the atmospheres of both the cathode and the anode chambers of a typical fuel cell, bubbled with O2 and H2, respectively, at room temperature and at 50 {degree sign}C.
Cr(VI) Reduction using Polyaniline Coating on RVC Electrodes
Authors: Porras Ana , Gutierrez Sivia , Vilches Florina , Alatorre Ordaz Alejandro , Herrasti Pilar
Published: November 2007

Polyaniline coatings electrodeposited by cyclic voltammetry on RVC electrodes are studied as a system to reduce Cr(VI) to Cr (III). Various polymer film electrodeposition conditions are assessed, such as the number of scans, anodic potential limit, monomer concentration and background electrolyte concentration. The results show that to achieve a high Cr(VI) transformation rate, deposits with a large polymer mass must be obtained, and that the structures must be as open as possible in order to afford the Cr(VI) greater permeability, thus increasing the conversion rate.
Electrochemical Oxidation of Arsenites, by an Anode of Reticulated Glassy Carbon as Previous Step for Removal
Authors: Perez Sergio , Lin Ho Shui Wai , Felix Rosa Maria
Published: November 2007

The main factor that affects the performance of the arsenic removal from water is its oxidation state. It is known that As (III) is harder to be removed than As(V) due to the fact that H3AsO3 is a nonionic compound with a pK1 = 9.22 while H3AsO4 (As(V)) dissociates ready with a pK1 = 2.25. In the oxygen- poor environment like in groundwater, arsenic exists mainly as As(III). For the purpose of obtaining a higher degree of removal of arsenic from contaminated groundwater, it is necessary to oxidize the As(III) to As(V) prior to the other treatment processes. In this work an electrochemical reactor, having an anode made from reticulated vitreous carbon of 100 pores per inch (100 ppi), was used to oxidize As(III) to As (V), this eliminates the need of adding more chemical substances to the treatment system. The performance of this special designed electrochemical reactor was evaluated at various applied cell voltages, reaction time, the concentration of the supporting electrolyte (NaCl), flow rate of the arsenic (As(III)) contaminated water through the electrochemical reactor and the pH of the aqueous media. Our experimental results indicated that for an aqueous solution containing 1.0 ppm in As(III) and at 3.0 volts applied cell potential with a flow rate at 10 mL/min and 0.10 M in NaCl, the percentage of oxidation of As(III) to As(V) was closer to 100%.