bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field trial of an ejector well dewatering system at Conwy, North Wales
Authors: Powrie W. , Roberts T. O. L. 
Published: November 2007

Abstract
An ejector or water jet pump is particularly suitable for pore water pressure relief applications in fine soils since it can operate at relatively low pumped flowrates, creating a vacuum at depth inside the well. A field trial of an ejector well dewatering system was carried out in laminated glacial lake deposits at Conwy, North Wales, in connection with the construction of the A55 Conwy Crossing. During the trial groundwater extraction flow rates and pore water pressures were monitored. Some of the ejector wells terminated in the bedrock underlying the lake deposits: in many of these, the groundwater extraction flow rates were high and the drawdowns achieved were relatively low. Back-analysis using conventional methods modelled closely the observed response of near-by piezometers. On the other hand, wells terminating in the lake deposits yielded low groundwater extraction flow rates and vacuums at about 500 millibar developed. In this case, conventional analysis substantially overpredicted both the rate and magnitude of drawdown in the surrounding ground. The reasons for this are as yet uncertain: nonetheless, the results of the trial demonstrate clearly the influence of the hydraulic boundary conditions on the performance of a dewatering system.
The passivity of steel in concrete
Authors: Leek Darrell S. 
Published: November 2007

Abstract
This paper describes the chemical nature of concrete and the internal environment in which the steel reinforcement is situated. The electrochemical basis for passivity of iron in aqueous solution is discussed and the anodic and cathodic reactions which occur are detailed in relation to pH-potential (Pourbaix) and current-potential (Evans) diagrams. The observed behaviour of iron in solution is compared to the behaviour of reinforcement in concrete. The breakdown of the passive film is discussed in relation to the commonly observed causes of deterioration of reinforced concrete i.e. carbonation of concrete, the presence of chloride ions at the steel surface and sulphate attack. Results of an SEM-EDS study of chloride-induced breakdown of the passive film are presented. The effects of the surface condition of the reinforcement prior to its inclusion in concrete and the use of latent hydraulic binders and thermosetting plastic coatings (fusion bonded epoxy) in relation to passivity and corrosion behaviour are discussed.
Chemical reaction between concrete and natural groundwaters and its implications for the commissioning of observation boreholes in chalk
Authors: Song Lin-Hua , Atkinson T.C. 
Published: November 2007

Abstract
Four purpose-constructed observation boreholes in chalk were found to contain water with pH of 10-11.5 and abnormal chemistry within fourteen months of commissioning. Experiments show that this was due to contamination by alkaline porewater solutions from the concrete grout used in construction. Contamination was still detectable nearly three years after construction but was cleared by pumping. A six-hour pumping test is recommended as standard procedure during commissioning of observation boreholes.
Some observations on a comparative aerial photography interpretation of a landslipped area
Authors: Fookes P. G. , Dale S. G. , Land J. M. 
Published: November 2007

Abstract
All aerial photography interpretation must be used with caution. When well done and supported by ground truth exercises they can be a valuable aid to site investigation, depending on the quality and scale of the aerial photographs and the skill and background of the interpreter.
A rare situation has arisen where eight interpretations of a landslip complex in gently folded Tertiary marine sediments overlain by young colluvium and covered by dense equatorial rainforest were made by different professional interpreters. This is used as an opportunity to illustrate the potential difficulty in obtaining a reliable interpretation.
Five of the interpretations were made without knowledge of a major new landslip which occurred in an area of existing landslips and three were made with knowledge of the new landslip, all using the same pre-major new landslip aerial photographs. Of the five made without knowledge of the new landslip, two did not identify existing landslips at the site and three partially identified landslips but each in a different configuration. With knowledge of the new landslip the interpreters identified old features in the aerial photographs similar to the features produced or exposed by the new landslip.
Hydrogeology of the Saq Formation east of Hail, northern Saudi Arabia
Authors: Hussein M. T. , Bazuhair A. G. , Ageeb A. E. 
Published: November 2007

Abstract
The study area lies about 120 km to the east of Hail in northern Saudi Arabia, covering a surface area of some 350 km2. The paper considers its general hydrogeological situation including information on groundwater occurrence and movements within the Saq Formation, aquifer parameters, groundwater composition and variation. Heavy pumping from 186 deep wells with an average discharge of 1800 gallons/min has resulted in a continuous drop in the groundwater level since 1982 and its effects on major ionic composition for the period 1982–1989 are discussed.
Sensitivity of sandstone strength and deformability to changes in moisture content
Authors: Hawkins A. B. , McConnell B. J. 
Published: November 2007

Abstract

The loss in uniaxial compressive strength between UCS
dry
and UCS
sat
for 35 British sandstone types is discussed. The difference between UCS
dry
and UCS
sat
for the clay-rich Cretaceous Greensand was 78% while for the Siliceous Sandstone the strength decreased by only 8%. Over the whole range of sandstones, however, the view that the weaker varieties are more sensitive to moisture content is not supported. The degree of sensitivity to moisture content is controlled primarily by the proportions of quartz and clay minerals present and to a lesser extent by the rock microfabric. Research indicates that the development of pore pressure during loading is negligible especially in pure sandstones and hence does not play a significant role in moisture related strength reduction.

The work has demonstrated a large variation in sensitivity to moisture content throughout the range of sandstones studied and has shown that an increase in moisture content of as little as 1 0.000000rom the dry state can have a marked effect on both strength and deformability. A classification scheme for moisture content sensitivity is proposed.
Application of shallow reflection techniques in hydrogeology
Authors: Davies K. , Barker R. D. , King R. F. 
Published: November 2007

Abstract
Shallow seismic reflection surveys have a range of application in groundwater investigations particularly where a precise solution to a subsurface problem is required. Recent surveys have mapped depth to bedrock, depth to water table, structure within alluvial deposits and the positions of old mineworkings. Example surveys from Down Ampney illustrate the application of shallow reflection surveys in the precise location of structural faults.
Automated monitoring and interactive data evaluation for a gravel aquifer in central London
Authors: Evans Neil A. 
Published: November 2007

Abstract
Scott Wilson Kirkpatrick was commissioned by CIRIA in 1990 to undertake an investigation into the impact of urbanization on the Thames Gravel Aquifer of central London. As a part of this investigation, a computerized approach to data handling was adopted. This paper describes the approach, from the use of downhole data loggers for monitoring groundwater and hydrological parameters, through to the analysis of field data using a lumped parameter model constructed on a spreadsheet and a geographical information system developed in-house. The advantages and disadvantages of this particular combination of computer hardware and software for aquifer monitoring studies are discussed.
A review of the attenuation of trichloroethylene in soils and aquifers
Authors: Bourg Alain C. , Mouvet Christophe , Lerner David N. 
Published: November 2007

Abstract
The transport, transformation, sorption and volatilization of trichloroethylene (TCE) as a non-aqueous phase liquid (NAPL) and as a dissolved aqueous constituent, under both laboratory and field conditions, are reviewed.
NAPL-TCE is expected to migrate quite rapidly in soils and other water-unsaturated conditions, leaving droplets of organic liquid in the pore spaces. At the water table level, TCE may stop its downward movement and diffuse laterally, together with a slow migration downwards. From there on NAPL-TCE will slowly dissolve in groundwater. However, some specific hydraulic characteristics may induce rapid transport downwards away from the water table.
TCE may appear in soils and aquifers as a result of its wide industrial use and also, possibly, as a degradation by-product of other chlorinated hydrocarbon solvents. TCE can undergo abiotic and (mostly) biotic, aerobic and (mostly) anaerobic transformations leading to less chlorinated ethenes. A half-life of 300 days was observed under field conditions.
Batch and column experiments show that TCE is weakly sorbed on soil and aquifer solids with linear partition coefficients. Retardation factors in the range of l to 9 are reported from laboratory and field investigations. The adsorption is almost fully reversible.
Gaseous TCE is more adsorbed than aqueous TCE, the extent of uptake being greatly influenced by the moisture content of the solid. Soil gas surveys appear as a promising technique for the study of soil and groundwater contamination by TCE.
NAPL-TCE contamination should be quite effectively removed by steam injection. Because of its low adsorption and weak degradation under aerobic conditions, the diffuse contamination of aquifers by dissolved TCE can be extensive. In the case of localized and more severe pollution, approaches for the restoration of aquifers based on pumping followed by treatment at the surface may be effective but they usually are not economical. In situ treatment by stimulating the biotrans-formation is considered as a favourable alternative.
Great Man-Made River Project, Libya, Phase I: a case study on the influence of climate and geology on concrete technology
Authors: Fookes P. G. , Stoner J. R. , Mackintosh J. 
Published: November 2007

Abstract
The paper discusses the principal climatic and geological features influencing the design and manufacture of the large (1.6 to 4m) prestressed concrete cylinder pipes used in the 1900 km of the wellfield collector and main conveyance lines of Phase I of the Libyan Great Man-Made River Project.
Pipe design and manufacturing processes are outlined and the winning and processing of aggregates are discussed. Particular reference is made to the extremely aggressive climatic and geological conditions and to the methods employed to overcome them successfully.
Simple generalized methods for estimating aquifer storage parameters
Authors: Younger P. L. 
Published: November 2007

Abstract

In many practical applications, hydrogeologists are called upon to predict aquifer behaviour in areas devoid of pumping test data. Estimations of transmissivity may sometimes be made from specific capacity records, but in general storage parameters (specific yield and storativity) are not readily obtainable. Existing methods for estimating these parameters are few and inaccurate, especially for storativity (
S
). By returning to the basic definition of confined aquifer storage, a simple method has been developed for estimating
S
as a function of aquifer lithology and thickness alone. Variations in aquifer porosity (which are often difficult to quantify) are neglected in this formulation and numerical experiments have shown that the errors introduced by this assumption are negligible except for indurated aquifers of low compressibility (α < 10-
10
ms
2
/kg). Porosity can be more easily determined for these aquifers than for unconsolidated aquifers of higher compressibility and a more accurate calculation of
S
can thus be made. This method has been tested against storativities derived from pumping test data for wells in the Altiplano of Bolivia and a good correlation between estimates and field values was found. The importance of obtaining good estimates for
S
is illustrated by reference to a typical problem encountered in a development project in the Altiplano, where the increased accuracy obtained using the new method (instead of older less rigorous methods) has beneficial consequences for the local community.
Geotechnical assessment of some charnockites from Nigeria as construction materials
Authors: Eze E. O. 
Published: November 2007

Abstract
Charnockites are a distinctive type of granite characterized by coarse-grained texture and the presence of pleochroic hypersthene and perthitic feldspars. They occur worldwide mainly in the Precambrian shield areas but are not as abundant as other rocks of granitic affinity.
Laboratory test results for three charnockites from Nigeria indicate good quality materials that are fairly comparable in many aspects with the more tried and tested granites. However, the coarse-grained texture, the relatively high percentage loss values in the aggregate crushing value test as well as the Los Angeles abrasion and sulphate soundness values, which only just meet acceptance limits seem to indicate possible poor performance, particularly where they are to be subjected to significant impact, cavitation and scour. The compressive strengths of the samples fall below 200 MPa, which is generally considered a good average value for aggregate for most civil engineering works. However, the disparity between test results and performance records of some rocks, local availability of a rock and the high ratio of transportation to production costs of crushed stone all militate against any disadvantage these somewhat poor test results may indicate charnockites have when compared with more established rocks.
Hydrogeochemistry of Millstone Grit and Coal Measures groundwaters, south Yorkshire and north Derbyshire, UK
Authors: Banks David 
Published: November 2007

Abstract

A pilot study has been performed to ascertain the baseline hydrochemistry of both shallow (springs) and deep (borehole) groundwaters of the Millstone Grit and Coal Measures. In terms of major ion composition the majority of the shallow groundwaters in the two formations are rather similar (typically Ca/Mg-SO
4
2-
/HCO
3
-
). The deep groundwaters show more variability. In some boreholes, marked seasonal temperature fluctuations and chemical compositions similar to shallow groundwaters indicate short residence times. In contrast, several boreholes in the Coal Measures indicate highly reducing conditions, evidenced by sulphate reduction and spectacular methane exsolution at two sites in Sheffield. Some deep Coal Measures groundwaters show elevated chloride concentrations compared with shallow waters, which may indicate the influence of deep formation brines, while others yield sodium bicarbonate waters indicative of cation exchange. At the other extreme, highly oxidizing conditions, e.g. in broken ground at the Mam Tor landslip, promote pyrite oxidation and yield acidic, ferruginous waters with high contents of heavy metals including uranium and thorium. At three sites in the Coal Measures, sampling of radon was feasible, yielding values in the range 8–32 Bq/l.
Land drainage and saline intrusion in the coastal marshes of northeast Norfolk
Authors: Holman I. P. , Hiscock K. M. 
Published: November 2007

Abstract

Land drainage has caused a significant increase in surface water salinity in the River Thurne catchment of northeast Norfolk which is related to saline intrusion in the underlying Crag aquifer. A survey of surface water C1 concentration revealed values ranging from <100 mg 1
-1
to >12 000 mg 1
-1
, with C1 exceeding 10 000 mg 1
-1
at the centre of the coastal marshes. In the sub-surface, an electromagnetic induction survey demonstrated elevated apparent conductivities of 100–200 mS m
-1
at the greatest exploration depth, except for areas having higher topography where fresh, or slightly brackish water persists. An electrical resistivity survey identified a low true resistivity layer (typically <1 Ωm), assumed representative of saline water, at a depth of typically <10 m below sea level under the coastal marshes. Higher land associated with dunes and isolated blocks of elevated land within the marshes gave a saline interface at 10–15 m below sea level, and beneath the catchment watersheds at >20 m. Solute transport modelling of an artificial vertical section through the aquifer supports the field observation that the distribution of surface water salinity is primarily determined by the spatial distribution of water levels in the main drains, all of which are maintained below sea level by pumping.
Modelling the hydraulic relationship between the River Derwent and the Corallian Limestone aquifer
Authors: Carey M. A. , Chadha D. 
Published: November 2007

Abstract
The River Derwent in North Yorkshire has been identified by the Environment Agency as a river with a high priority for flow alleviation due to low flows during summer months. The river flows across the Corallian Limestone aquifer and loses flow to this aquifer, via a set of solution hollows in the stream bed. This loss in flow has been gauged, as of the order of 15 to 35 Ml/day, and in dry years the entire river flow can be lost to the aquifer. Groundwater abstraction from the Corallian Limestone aquifer varies seasonally, and is currently between 25 and 35 Ml/day, with the higher rates of pumping occurring during the summer months. One of the main groundwater abstractions is for public water supply, and this source is located about 1.5 km from the river. Abstraction from this source is largely sustained by the leakage from the river.
The Corallian Limestone aquifer and its hydraulic relationship with the River Derwent has been represented using the USGS modelling package MODFLOW, to improve the understanding of the flow regime and to provide a tool to assist in the evaluation of different water resource management options. This model has provided a good representation of the aquifer system, and in particular has shown that leakage from the River Derwent is a key factor in controlling the groundwater regime and in maintaining a water balance for the aquifer. The model has been used to examine different management options for the aquifer system, including the influence of reducing the volume of water available to leak through the river bed on the groundwater abstraction sources.
This paper will describe how the model has been applied to this aquifer system, the benefits obtained and the problems encountered.
Determination of aquifer properties in northern Qatar for application to artificial recharge
Authors: Streetly M. J. , Kotoub S. 
Published: November 2007

Abstract
The aquifer system in Qatar has been heavily exploited for agricultural purposes for over 20 years, leading to a decline in groundwater quality. In 1992 the Ministry of Municipal Affairs and Agriculture appointed Entec to carry out a two-year study into the feasibility of using artificial recharge to restore the aquifer system. This study involved field testing and modelling of the Rus and Umm Er Radhuma (UER) aquifers at four sites. Step, constant rate and tracer injection/reabstraction tests were carried out on each aquifer at each site.
The step tests on boreholes in the UER indicated that non-Darcian behaviour occurred in the aquifer and extended a significant distance from the pumping boreholes. This was not observed during the step tests on boreholes in the Rus. A variety of techniques were used to analyse data from the constant rate tests and these provided a range of values for standard aquifer parameters as well as allowing a conceptual model of flow processes in the aquifer to be developed. This understanding was used in developing finite difference solute transport models to replicate the results from the tracer tests. Values of dispersivity of 0.5–5 m were derived for the Rus aquifer whilst values in the range 10–150 m were derived for the UER. Effective porosities were high at around 0.2 for both aquifers.
An introduction to stone colonizing micro-organisms and biodeterioration of building stone
Authors: Wakefield Rachael D. , Jones Melanie S. 
Published: November 2007

Abstract
Over the last decade, the concept of stone decay being caused solely by one or two processes has been revised in favour of a more holistic notion that many operate together, are synergistic and possibly cyclical or seasonal. Certain of these processes may become predominant over others at particular times of the year or at specific periods in the history of the stone. Many researchers from different disciplines now agree that biological deterioration is of significance, and cross disciplinary work is becoming the rule rather than the exception. This short introduction gives an overall view of the principal mechanisms important in stone biodeterioration. The main groups of micro-organisms found on stone and their role in stone biodeterioration are reviewed. The final section discusses decay processes which can be brought about by many different groups of micro-organisms living together as a complex microbial community at the stone surface.
Weathering of sandstone by alunogen and alum salts
Authors: Williams R. B. G. , Robinson D. A. 
Published: November 2007

Abstract
In many places in eastern Germany, the Czech Republic and southern Poland, outcrops of the Elbsandstein are undergoing rapid honeycomb weathering and scaling in the presence of gypsum, alunogen and alum salts. Laboratory experiments have been undertaken to test the relative efficacy of these salts as weathering agents. Cubes of Lower Cretaceous sandstone from West Sussex have been repeatedly soaked in salt solutions and then oven dried at 50°C. The experiments show that alunogen causes relatively little damage, but alum salts are highly destructive, especially if gypsum is present. The addition of gypsum reduces the damaging effects of alunogen, while gypsum on its own causes minimal weathering.
Putting numbers to geology—an engineer's viewpoint
Authors: Hoek Evert 
Published: November 2007

Abstract
Assigning numbers to geology requires a delicate balance between the commonly held opinion that geology cannot be quantified and the over-optimistic view that every physical quantity can be described in precise mathematical terms. In reality, many geological characteristics cannot be quantified precisely and intelligent guesses based upon experience and logical arguments are the best that can be hoped for.
This paper explores the processes used to make some of these guesses and describes how the results are then applied to engineering design. It is shown that, with care, rational engineering decisions can be made in spite of the limitations of the input data. In recent years the development of computer hardware and software has made it much easier to investigate the influence of ranges of values for each of the input parameters. However, care has to be taken that the design is driven by sound geological reasoning and rigorous engineering logic rather than by the very attractive images that appear on the computer screen.