bluuebunny/crossref_metadata_2025 huggingface dataset:
Flood Generation Modelling
Authors: CALVER ANN
Published: July 2007

This paper summarizes recent research and development of a particular process‐based runoff generation model, the Institute of Hydrology Distributed Model. Surface and subsurface flow equations are linked in a hydrologically appropriate system to allow simulation of catchment runoff processes. Predictions can be made of channel flow, surface runoff and subsurface flow, pressure potentials and water contents. The structure and methods of the model are described and its data and computing requirements are outlined. Field and systematic applications are discussed, together with the work carried out on providing guidelines for use for the wider hydrological community.
The 1988–92 Drought in its Historical Perspective
Authors: BRYANT S. J. , ARNELL N. W. , LAW F. M.
Published: July 2007

During the period 1988–92, the south and east of England were subjected to drought conditions. Data from 10 catchments and three groundwater level records were analysed using runoff and groundwater deficit indices to place the drought in its historical perspective. In parts of eastern England the drought was the most extreme – in terms of runoff deficit – for at least 150 years. It was less notable in other parts of southern England, but still extreme.
Water and Sewerage Charges in Scotland
Authors: BOLTON P. W.
Published: July 2007

The paper outlines the statutory arrangements governing water and sewerage charges in Scotland, and comments on the factors affecting the levels of charges. Trends in revenue expenditure over the period 1989–90 to 1992–93 are considered in relation to increases in personal community water charge levels, metered water rates, and costs per household. Non‐domestic sewerage rates and industrial effluent charges are also discussed. Some comparisons are made with England and Wales and with other countries. The funding arrangements for capital expenditure and their effect on the levels of charges are described, with particular reference to debt levels and rising expenditure to meet UK and EC standards. Factors affecting future charge levels are also identified.
The Health Effects of Low‐Contact Water Activities in Fresh and Estuarine Waters
Authors: FEWTRELL L. , KAY D. , SALMON R. L. , WYER M. D. , NEWMAN G. , BOWERING G.
Published: July 2007

Four studies were carried out at separate locations to investigate the relationship between health effects and low‐contact water sports, and intensive microbiological sampling was conducted in parallel to the health studies at each site. The two sports examined were marathon canoeing and rowing.

The extremes of water quality were at the estuarine sites on the River Torridge, where pollution levels varied from a geometric mean faecal coliform value of 62/100 ml at the Appledore/Instow site to 4613/100 ml at the Bideford site.

A comparison of ‘exposed’ and ‘unexposed’ groups, 5–7 days after exposure, showed that the health effects of low‐contact water sports are minimal, within the water quality ranges which were studied.
The Management of Water Colour in Peatland Catchments
Authors: PATTINSON V. A. , BUTCHER D. P. , LABADZ J. C.
Published: July 2007

The problems of water‐colour management in peatland catchments are discussed. Colour may be managed in three areas of the reservoir catchment system: on the catchment itself, in the channel/conduit system and within the reservoir. Whilst a number of workers have considered the management of catchment areas and some have evolved tributary turnout strategies, no previous research has considered the role of the reservoir in the amelioration or enhancement of water colour. The management of water colour at Thornton Moor catchment (near Bradford) is described. In this catchment a staged approach has been adopted, with colour being managed in an integrated manner at three stages along the catchment/conduit/reservoir system.
Environmental Dredging on the Birmingham Canals: Water Quality and Sediment Treatment
Authors: BROMHEAD J. C. , BECKWITH P.
Published: July 2007

Sediments in sections of the central Birmingham canals are heavily contaminated with heavy metals and mineral oils. The sediments promote high levels of metals within the water column, which suppress the establishment of aquatic vegetation and fisheries. Sediment disturbance by boat traffic results in the release of mineral oils which cause unsightly surface oil sheens.

Studies into a variety of treatment methods indicated that removal and ex‐situ treatment of the contaminated sediments would significantly improve water quality and result in environmental benefits.

Funding from Birmingham City Council and British Waterways enabled the award of a contract with a value of approximately £800000 and commencement in February 1993 for the removal and processing of about 24 000 m3 of sediments by soil washing prior to off‐site disposal. The nature of the sediments and water are reviewed, and the results of the soils washings are discussed. The impact of the dredging operations on water quality was monitored during the works and generally observed to be localized. An environmental management plan is now being implemented and the objectives for this are discussed.
Urban Sewerage Rehabilitation in the UK
Authors: HURLEY R.
Published: July 2007

This paper reviews the history of sewerage rehabilitation in the UK and the work which led to the publication of the Sewerage Rehabilitation Manual in 1983.

The Sewerage Rehabilitation Manual planning procedure is described, and experience of its implementation since 1984 is discussed. Reference is made to changes in the water industry brought about by privatization, and to recent European and UK legislation. The current status of the rehabilitation market is then discussed and possible future developments are outlined.

The paper concludes that the existence in the UK of a standardized rehabilitation planning procedure has enabled sewerage problems to be solved more cost‐effectively than previously and has helped the industry to cope with the major changes brought about by privatization. Compatibility with the proposed European standard for sewerage rehabilitation will enable UK and European strategies to develop together.
Drainage from Roads and Airfields to Soakaways: Groundwater Pollutant or Valuable Recharge?
Authors: PRICE M.
Published: July 2007

The construction of a road, runway or other paved surface on the outcrop of an aquifer introduces an impermeable area into an otherwise permeable environment. Surface water must be drained from these areas, and the most convenient and inexpensive way of disposing of this water is usually to lead it into soakaways in the unsaturated zone of the aquifer. This approach is acceptable in that it can provide valuable recharge to aquifers in times of low rainfall. However, it carries the risk that pollutants from the surface can also be carried into the aquifer. These pollutants can be generated from (a) normal abrasion, (b) maintenance operations such as de‐icing and defoliation, and (c) accidental spillages. Although there is evidence that such drainage can carry a pollutant load, and that drainage entering soakaways can reach a public‐ supply well, there does not seems to be any evidence available at present of any public supply in the UK being seriously affected by such drainage.
Contaminated Ground Investigation: Matching Techniques to Site Conditions
Authors: CROWCROFT P.
Published: July 2007

The investigation of contaminated ground is now undertaken as a matter of course at sites which have an industrial history, and also at supposed greenfield sites, to prove their ‘cleanliness’. This paper reviews the hazards which are likely to be encountered on contaminated land, and describes the range of traditional and innovative investigative techniques used at present to obtain a full perspective of the problem. Several case studies are presented which not only highlight the value of particular investigative techniques, but also show the need for caution in interpretation of data and the desirability of confirmation by other methods.
Developments in the Thermal Drying of Sewage Sludge
Authors: LOWE P.
Published: July 2007

The application of heat to dried sewage sludge has been practised by the water industry for many years. Early technologies were effective but their utilization of energy was not so efficient. Other industries have faced up to this problem and, as a result, have developed thermal‐drying techniques which are more efficient and therefore more cost effective. In recent years, the transfer of this technology to sewage‐sludge drying has been taking place, and some companies have designed dryers specifically for this purpose. Commercial and legal pressures have also focused attention on the final product and its use in agriculture, horticulture, land reclamation, landfill, incineration, and as a substitute for fuel.

This paper reviews the work which has been undertaken to determine the changes which occur as sewage sludge is dried, and discusses the technology which is available at present. Factors influencing capital and operating costs and product choice are also included.
Water Supply Franchising in Buenos Aires
Authors: WALTON B. , BATEMAN J. S. , HEINRICH M.
Published: July 2007

This paper outlines the approach which was recently adopted by the Government of Argentina for the franchising of water services in Buenos Aires. It briefly reviews the water and sewerage services in the area and outlines the operation, background and process which were adopted by the Government to secure the franchise. The paper explains the circumstances and objectives, and describes how the franchising process developed both politically and organizationally. It also examines the franchisee and selection process, the bidding requirements, and organizational arrangements which enabled a successful transfer of the water services from public to private sector.
Waste Management Licensing: Challenges for Waste Regulation Authorities
Authors: READ S. V.
Published: July 2007

The introduction of a new and strengthened Environ‐ mental Protection Act 1990 waste management licensing system in May 1994 presented waste regulation authorities in England and Wales with important challenges in respect to the technical and legal issues surrounding this work. However, other important strategies and policies, a system of fees and charges which implements the ‘polluter pays’ principle, and initiatives relating to the Citizens Charter and market testing, may have a more profound impact on waste regulation authorities and require a fundamental reappraisal of their strategies.

The author argues that waste regulation authorities need to develop a marketing approach to the development of their strategies and policies in the future, if they are to satisfy their customers and provide the excellent service which is expected of them.
Maintenance and Operational Costs of Vacuum Sewerage Systems in East Anglia
Authors: CONSTERDINE P. EUR J. P.
Published: July 2007

Vacuum sewerage, as an alternative to conventional systems, is reasonably well known, and most civil engineers are aware that there can be significant capital savings on construction costs. These can be readily demonstrated on paper at the initial stages, but maintenance costs can only be determined from experience.

This investigation into the maintenance costs of the first two public vacuum sewerage schemes constructed in the UK compares the operational costs which were established and recorded in 1982‐83 by South Holland District Council with those recorded in 1992‐93 by Anglian Water Services Ltd.

The main body of evidence available is in the form of papers and reports prepared by Anglian Water's engineers who were taking a keen interest in this technology and monitoring its performance carefully.
Full‐Scale Testing of Mechanically Raked Bar Screens
Authors: MEEDS B. , BALMFORTH D. J
Published: July 2007

Combined sewer overflows are a known source of aesthetic pollution in urban watercourses, and screens have traditionally been used as a means of preventing such pollution. The authors have established the effectiveness of combined‐sewer overflow bar screens in preventing the visual pollution of rivers and have determined the factors which influence screen efficiency so that guidance can be given on improving the performance of future installations. A field study has been undertaken to monitor existing bar screens with different bar spacings. The hydraulic performance of the overflow chambers has been established, and the sources and type of visual pollutants have been identified. Analysis of the field data has established that screen performance (for the main polluting solids) depends on (a) screen bar spacing, (b) mean rate of flow through the screens, and (c) frequency of raking. Overall, mechanically raked bar screens are likely to achieve retention efficiencies of less than 50%.
The Sanitary Administration of Belfast in the Mid‐1990s
Authors: LAMONT J. R. , McMANUS E. W. , SUTTON G. K.
Published: July 2007

The paper presented in 1898 by F. W. Lockwood (a) provided a detailed description of the many and varied factors contributing to the health and welfare of the population of Belfast, and (b) took a forward look as to where improvements could be foreseen. This paper considers the issues which were raised almost a hundred years ago and assesses the changes and developments in the fields of politics, legislation, demography, topography, water, sewerage, environmental health, public health, waste management and housing. It is likely that Lockwood would be satisfied by the overall improvement to people's general health and their environment, although the utopia he wished for is still some way off.
Design of Settlement Tanks and the use of Chemicals to Aid Precipitation of Suspended Solids
Authors: BOON A. G. , DOLAN J. F.
Published: July 2007

Traditionally, the design of settlement tanks has been based on practical experience linked to key criteria, which have evolved from many sources. In this paper, the design criteria which affect the performance of both primary and secondary tanks are examined and a procedure, linked to critical velocities and loading rates, is put forward to enable the design requirements to be rationalized.

Based on the authors’ considerable practical experience, the proposed procedure can be used with confidence to design tanks which will achieve required performance, particularly in the case of secondary tanks (for separation of both activated and humus sludges). In particular, the importance of a correctly sized inlet stilling chamber, to reduce the feed velocity to around 0.003–0.005 m/s is explained.

The use of chemicals to aid removal of suspended solids (and hence BOD) has been practised for many years. Today, there is renewed interest, particularly for phosphate removal and for the treatment of some industrial wastewaters. The composition and nature of sewage affects the potential benefits of coagulant chemicals when added at the treatment works’ inlet. The introduction of organic polymers has significantly improved performance and reduced costs. The major disadvantage of using chemicals relates to the significant increase in quantity of sludge that is produced, which will require both treatment and disposal, increasing operational costs.
Development of the Sludge Thermal‐Drying Option for South West Water
Authors: BROWN M. J. , WHIPPS A. P.
Published: July 2007

Sewage‐sludge production in South West Water is predicted to more than double, to about 50000 dry tonnes per annum, by the turn of the century. Staff of South West Water Services have carried out a strategic review of sludge utilization and treatment options, and have developed a strategic planning computer model to assist in the financial evaluation of the many options which are available. The strategy allows for the provision of new raw sludge thermal‐drying facilities for the anticipated increase in sludge production.

Trials were carried out with an indirect dryer system to develop and investigate the operational issues and use of the dried raw product. The initial trial produced a fluffy, low‐density material with poor storage and handling characteristics, apparently associated with the high‐fibre content of the sludge. The process has been modified to include pelletization.
The Toxicity‐Based Consent and the Wider Application of Direct Toxicity Assessment to Protect Aquatic Life
Authors: WHARFE J. R. , Tinsley D.
Published: July 2007

This paper describes the value of, and progress towards, introducing direct toxicity assessment procedures for use in water quality management within the UK. The capabilities and limitations of direct toxicity assessment are compared with those of the conventional substance‐specific control and bio‐assessment measures. Progress towards the introduction of toxicity‐based consents, following an agreed strategy and standardized procedures, is reported together with the wider application of direct toxicity assessment to monitor the receiving environment. Finally, the selection of suitable ecotoxicological methods and their further development for direct toxicity assessment, are presented.
The Thames Water Ring Main: The Future
Authors: Bensted I. H
Published: July 2007

Commissioning of the Thames Water ring main Phase 2 tunnels in the spring of 1994 signalled an important milestone for major investment on London's watertreatment and trunk distribution systems. This included not only the ring main itself, but also the progressive installation of advanced water treatment processes in the water‐treatment works supplying the city, due for completion at the end of 1998.

This paper reviews the benefits of the ring main and looks at future developments, focused largely in local distribution rehabilitation and leakage control. The objectives and benefits of future possible extensions of the ring main are discussed, and a configuration is put forward as potential for development in the long term.
Gross Solids' Movement in Sewers: Laboratory Studies as a Basis for a Model
Authors: Davies J. W , Butler D. , Xu Y. L
Published: July 2007

A simple model of gross solids' movement in sewers is proposed, based upon the results of studies of part‐full pipe flow in two laboratory installations, under steady and unsteady flow conditions. The model covers advection and deposition, and is intended as one component in a comprehensive model of the behaviour of gross solids in sewers. Such a model is needed because gross solids are not included in the currently available sewer‐flow quality models, even though they can cause pollution which is of particular concern to the public

The paper describes the laboratory studies and their results. It sets out the principles of the proposed model and explains why these differ from existing models of dissolved and fine suspended pollutants.
Evaluation of Lake Vyrnwy within the Integrated Water Supply Systems of North West Water
Authors: Ringham J. E. , Walker S. , Wyatt T.
Published: July 2007

ABSTRACT In 1992, the National Rivers Authority published a discussion document on the National Water Resource Strategy which highlighted the future probability of a water‐supply deficit in the south‐east and a surplus in the north and west of England and Wales. One suggestion for rectifying this imbalance was to divert Lake Vyrnwy water which, at present, supplies Liverpool. This would allow further regulation of the River Severn, and subsequent transfer to the River Thames. Joint investigations by the National Rivers Authority and North West Water have established the implications of this diversion on the existing water resources and supply systems of North West Water.

The studies considered (a) the relationship between increased regulation releases, and reduced direct supply rates from Lake Vyrnwy, (b) the investment and operating cost implications of replacing Lake Vyrnwy supplies from sources within the southern command zone or by transfer from the northern command zone, and (c) the potential operational difficulties.

The paper describes how each of these aspects has been addressed. The results demonstrate the necessity of evaluating Lake Vyrnwy as a component of the integrated water supply systems of North West Water, and of other parts of the country.
The Effectiveness of the Land‐Drainage Consent System
Authors: Day R. A. , Fenner R. A.
Published: July 2007

ABSTRACT This paper presents the results of a study into the effectiveness of the land‐drainage consents system. The investigation studied eighteen main river reaches, each 2 km in length, in the north‐east Thames region. All works within the main channel and the 8 m margin, subject to the regulations in the Water Resources Act 1991, were recorded. The impact that each of these works might have had upon the environment, including the ability of the river to pass the peak flow and the potential for an increase in pollution, has been assessed and an overall impact rating for each reach has been determined. Each of the works identified on the reaches has been cross‐referenced with consent records held by the National Rivers Authority. Results that indicate that a high proportion (92%) of works do not have consent under the present system.
A Review Of Road‐Gully Spacing Methods
Authors: Davis A. , Jacob R. P. , Ellett B
Published: July 2007

ABSTRACT Methods of spacing gullies on surface‐water drainage schemes have changed significantly during the last thirty years as the understanding of the hydrology and hydraulics of the subject has advanced. Rules of thumb which take no account of road geometry or inlet efficiency have been replaced by more rigorous methods, the most advanced of which considers time‐varying intensity storms. The methods currently used are not consistent and vary in their approaches. This paper reviews the methods used in the past, and discusses the methods which are currently employed at present.
Strategies for Handpump Water Supply Programmes in Less‐Developed Countries
Authors: Carter R. C. , Tyrrel S. F. , Howsam P.
Published: July 2007

ABSTRACT Community water supply programmes in developing countries frequently utilize wells or boreholes equipped with handpumps as the technology of choice. Whilst simple targets concerning numbers of wells to be drilled or villages to be served are often prominent, the wider objectives of such programmes are rarely expressed in quantified terms and, as a consequence, programme impact is often disappointing as well as difficult to evaluate. Because objectives are not clear, programme strategy fails to include all the issues and activities which are necessary to achieve the maximum beneficial impact on participating communities. In the paper, target objectives, checklists of programme activities, and staffing requirements are proposed. The subject of programme impact is briefly discussed, and a realistic approach to programme evaluation is outlined. The paper is intended both as an aid to project planners and as a guide to managers and evaluators of existing well‐handpump programmes.
The Management of Sediment in Reservoired Catchments
Authors: White P. , Labadz J. C. , Butcher D. P.
Published: July 2007

The rates of sedimentation in Yorkshire reservoirs are high for the UK but low compared with those reported globally. Whilst not likely to jeopardize supply, the behaviour and properties of reservoir sediments have implications for the quantity and quality of the water.

Data suggest that the use of control and diversion structures reduces average sedimentation by 53m3/km2 per annum in the case of residuum lodges, and also modifies the nature of the sediment considerably, tending to allow the finer, organic particles into the reservoir. Trapping may be minimized by the diversion of high flows where such facilities exist, or by maintaining water levels at the maximum possible in supply reservoirs.

Management strategies to reduce sedimentation would, in many cases, require fairly simple routine maintenance of existing structures. The short‐term cost of discarded water must be weighed against the longer‐term benefits of improved quality and reservoir capacity.
The Microbiology of Lubricants and Oils for Water Supply Applications
Authors: Sidorowicz S. V.
Published: July 2007

Recent work in the US has shown that contact between lubricants and oils and drinking water can promote the growth of heterotrophic micro‐organisms. It is unlikely that these species are pathogenic, and therefore harmful to man. However, the hygienic status of water distribution systems could be affected, leading to higher heterotrophic plate counts during routine sampling. Experimental work has been undertaken to study the microbiological impact of a range of lubricants and oils on drinking water. The methods have been based on an existing procedure for the assessment of the growth potential of drinking water, i.e. the ‘assimilable organic carbon’test. The results of this work could serve as the basis of a future standard method for the rapid and inexpensive screening of oils and lubricants for their microbiological suitability in potable‐water applications.
The Removal of Bromate from Potable Water Using Granular Activated Carbon
Authors: Mills A. , Belghazi A. , Rodman D. , Hitchins P.
Published: July 2007

Bromate in drinking water, at a level of microgrammes/litre, is a problem in ozonated waters but can be adsorbed, to a certain extent, by granular activated carbon. The adsorption capacity of granular activated carbon for bromate is significantly lowered when there are high concentrations of other anions, most notably chloride and sulphate, present in the water.
Developments in UK Reservoir Engineering and Management
Authors: Johnston T. A. , Millmore J. P. , Macdonald A.
Published: July 2007

This paper presents an overview of recent developments in reservoir construction and maintenance in the UK. It highlights the increasing importance of environmental issues to successful scheme promotion and provides advice on the key issues which need to be addressed. Research into dam safety is leading to further guidance for engineers in assessing existing structures. Comments are made on future capital expenditure on the existing stock of dams, and the status of dam safety legislation is reviewed.
The Effect of Agitator Impeller Design on Maximum Shear Stress, and the Resulting Impact on the Flocculation Process
Authors: Griffiths S.
Published: July 2007

Although it is extensively researched, flocculation in the water‐treatment industry lacks a design procedure to assess accurately the performance of the different types of agitator impeller which are available. New high‐efficiency, hydrofoil‐type impellers offer substantial potential for flocculation duties in many areas, provided that they are applied correctly. This paper highlights the importance of the ‘velocity gradient’and the distribution of shear within the agitation system. The objective of the paper is to help engineers to evaluate different types of proprietary impeller designs, using various techniques to examine the shear distribution applied to the system.
Implementing Environmental Management Systems in the Finfish Aquaculture Industry
Authors: Gavine F. M. , Rennis D. S. , Windmill D.
Published: July 2007

Environmental management systems are being implemented in many sectors of industry in order to assist organizations to (a) comply with legal requirements minimizing impacts on the environment, (b) reduce waste, and (c) gain an advantage in the market place. This paper provides guidance on the elements which should be incorporated into an environmental management system for finfish aquaculture operations in the UK.
The Channel Tunnel's Marine Works for Spoil Disposal
Authors: Maddrell R. J.
Published: July 2007

After many trials and about 10 000 years, land access between Britain and the Continent was re‐established in 1991 by the Channel Tunnel link, owned by Eurotunnel and built by a consortium of contractors, Transmanche‐Link.

The Channel Tunnel Act allowed Eurotunnel to construct two 8.5 m dia. running tunnels and a 5.4 m service tunnel, with the chalk spoil disposed of as a platform at the toe of Shakespeare cliff. The platform was on the critical path because it was also the main marshalling area for tunnel construction.

Spoil disposal was a major logistic and planning issue and required nine consents from various statutory bodies. Environmental issues were important and formed part of the 121 design‐related studies which included site investigations.

About 5 million m3 of spoil were disposed of in five sequentially developed lagoons, all of which had to be closed before the spoil could be placed. The completed platform, now known as Samphire platform, is a nature area with a small area for Eurotunnel's cooling plant.
A Simple Aid for Designing Sewers
Authors: Broome J. M.
Published: July 2007

A method for constructing design charts for the rapid selection of sewer diameter and gradient is described. A variety of design criteria for sewer capacity and minimum gradient can be incorporated in the chart, which may be adapted for different ranges of pipe diameter and material. The use of the chart should ensure that the most economical combination of pipe diameter and gradient can be chosen without the need for calculation.
River Thames Flood Hydrology Design Curves
Authors: Dunsmore S. J.
Published: July 2007

A quick method of defining design peak flows and hydrographs for any point on the River Thames between Days weir and Teddington is offered as a design tool for flood analysis. This paper presents the findings of a flood frequency and flood hydrograph analysis for the River Thames. The results were used in a hydraulic analysis of the river and its floodplain at Reading, but showed a wider application of the method on the river.
Sewage Sludge Recycling to Agricultural Land: the Environmental Scientist's Perspective
Authors: Towers W. , Horne P.
Published: July 2007

During the next fifteen years, the recycling of sewage sludge to agricultural land will increase significantly in Scotland as a result of EC regulations. This paper describes how soils and related environmental data around Edinburgh can be interrogated and interpreted to assess (a) the suitability of land for sludge utilization, (b) the risk of water pollution in relation to different soil conditions, (c) the ability of soils to adsorb potentially toxic elements in the sludge to prevent transfer to water or plants, and (d) the operational security and environmental sustainability of sludge recycling. The interpretations can make a valuable contribution to the appraisal of sludge disposal policy and implementation, and provide a framework for technology transfer between engineering, environmental and agricultural interests.
Managing Emergencies: Be Prepared!
Authors: Buckley C. B.
Published: July 2007

The successful management and resolution of emergencies affecting water quality is dependent upon easily accessible and well‐documented, user‐friendly information systems to support the decision‐making process. Well‐rehearsed emergency procedures must remain a vital component in the liaison and communication matrix of all organizations to ensure that the emergency is being managed in a competent and professional manner, particularly when public health is at risk.

Careful planning is needed to ensure that the necessary facilities and resources are readily available, and this aspect may have significant budgetary implications. Arrangements, to ensure that staff (at all levels) are fully aware of their responsibilities and roles during emergencies, must be secured by a well‐structured training programme, supplemented by periodic refresher courses and planned exercises accompanied by structured debriefing sessions.
Shipping and Handling of Pesticide Cargoes: the Need for Change
Authors: Johnston P. , Marquardt S. , Keys J. , Jewell I
Published: July 2007

Of all the dangerous goods carried at sea, pesticide cargoes are unique in the dangers which they pose to the environment. In 1991, the UN International Maritime Goods Code was amended to require that specified chemicals be labelled as ‘marine pollutants’. In addition, packaging must now allow for immersion in seawater and include attempts at salvage. The potential hazards of pesticide cargoes have been illustrated by a number of accidents involving shipping and there is an urgent need to expedite the provisions of the code. Also, many pesticides which are exported are not registered for use in the country of origin. A good case exists for linking the provisions of the code to the registration process and to the ‘prior informed consent’procedure and developing ‘convention’.
Tradeable Rights for Water Abstraction
Authors: Streeter R.
Published: July 2007

The Environment Agency has a statutory duty to secure the proper use of water resources, which is now considered inter alia to include an economically efficient allocation of resources as far as is possible within the current legislation. This paper considers the practical extent to which water rights can be traded within the existing system of regulation as a means of (a) improving the economic efficiency of resource allocation, and (b) satisfying customer demand for additional supplies. Outline proposals are also made for deregulation of current legislation to encourage further trading through less restrictive regulation.
Recent Developments in the Biological Filtration of Sewage to Produce High‐Quality Nitrified Effluents
Authors: Boon A. G. , Hemfrey J. , Boon K. , Brown M.
Published: July 2007

The biological filtration of sewage remains the process which is most commonly used for small works in rural areas throughout the UK. In many cases, the need to produce an effluent of high quality with full nitrification is essential in order to comply with the standards set by the Environment Agency. Traditionally, design loading rates of biological filters have been based on historical experience of performance, and on relatively short‐term statistical evaluation of the performance of a large number of treatment works, using average and maximum values for flow and loading rates. Many works which were designed on such information have failed to nitrify consistently, particularly during the winter and spring months.

This paper describes the detailed evaluation of six full‐scale, biological‐filtration sewage‐treatment works over a period of two years, in which there were significant changes in sewage flow rate, composition and temperature, from summer to winter. The key parameters which influence the production of high‐quality nitrified effluents were determined. The conclusions are used to provide a detailed guide on the design of conventional‐media biological filters to produce, consistently, fully‐nitrified effluents.
The Benefit: Cost Analysis of River Maintenance
Authors: Dunderdale J. A. L. , Morris J.
Published: July 2007

River maintenance, involving vegetation control and channel clearance, is carried out to facilitate flood alleviation and land drainage; increasingly there is a need to justify this expenditure against the benefits obtained. This paper presents the results of a study which was carried out to assess the economic performance of river maintenance on selected rural sites in England and Wales. The evaluation methods have been simplified to provide standard data and routines for river maintenance justification in the form of guidelines, elements of which have been incorporated into‘flood defence management system’methodology.
The Impact of Micro‐Hydropower on the Aquatic Environment
Authors: Copeman V. A.
Published: July 2007

This paper considers the impact of‘run‐of‐river’micro‐hydropower on the aquatic environment, focusing on the Afon Ty'n‐y‐Ddol in Snowdonia. Hydrological modelling of the abstracted reach shows that up to 50% of the annual flow is abstracted for power generation. A sediment and benthic macro‐invertebrate study down the reach showed no significant adverse consequences due to the altered hydrological conditions when subjected to individual taxa, diversity, or quality index analysis. A reduction in‘average score per taxa’immediately below the abstraction point may require further research.
Quantitative Risk Assessment for Incineration: Is It Appropriate for the UK?
Authors: Harrop D. O. , Pollard S. J. T.
Published: July 2007

The economic benefits of waste‐to‐energy plants are well known, but what are the environmental concerns? Public anxiety with regard to the development of incineration plants has focused attention on the need for informed and transparent assessment procedures based on sound science, to ensure that the impact of such developments is acceptable from an environmental perspective.
Reconstruction of Bray Weir on the River Thames
Authors: Higgs A. W. , Campbell G. G. , Dunn P. J.
Published: July 2007

Bray Weir on the River Thames near Maidenhead was refurbished during the summers of 1993 and 1994. The existing structure, which had become unsound and unsafe to operate, was replaced by nine vertical‐lift (or buck) gates. Construction works within a cofferdam and utilizing floating plant were undertaken in two phases. Following demolition of the existing weir, a network of reinforced concrete beams was supported on new driven piled foundations. Twin leaf gates slide in guides and span between new steel A‐frames, and are lifted by pairs of threaded spindles rotated by actuators operating through gearboxes. Fine flow control is achieved by allowing overtopping of the upper leaves of the gates. Following commissioning, operational difficulties resulting from seal vibration and excessive friction on the spindles necessitated design modifications.

This paper outlines a brief history of the site, the design options considered, the contract strategy employed, and includes a description of the construction phase and subsequent postcommissioning aspects.
The Wansbeck Barrage Scheme: Twenty‐One Years of Environmental Impact
Authors: Worrall F. , McIntyre P.
Published: July 2007

The Wansbeck barrage (in Northumberland), which was completed in 1975, was envisaged as a means of removing unsightly saltmarsh and creating an amenity lake and country park. This study examines the effect of the scheme on the estuarine environment and focuses on (a) the nature of the habitat, (b) the rate of sedimentation, (c) the control on water quality within the impoundment, and (d) amenity use.
Pumps as Turbines and Induction Motors as Generators for Energy Recovery in Water Supply Systems
Authors: Williams A. A. , Smith N. P. A. , Bird C. , Howard M.
Published: July 2007

Pressure‐reducing valves, which dissipate energy, are often used in water supply systems to regulate the downstream pressure levels. If a reverse running pumpset is installed alongside such a valve, most of the dissipated energy can be recovered.

This paper describes a system of this type which has recently been installed by North West Water, with advice and specialized equipment supplied by the Nottingham Trent University Micro‐Hydro Group. The power produced by the energy‐recovery system is used to run and monitor a remote potable‐water dosing plant.
Refurbishment of Five Ancient Weirs on the River Avon
Authors: Hindle J. , Kirby I. , Treadgold P.
Published: July 2007

This paper reviews the work which was carried out during the Avon Weirs Project ‐ from feasibility through site investigation and detailed design, to construction. The design included measures to (a) ensure the stability of the structures against uplift and piping failure, and (b) provide protection to the bank and bed of the river. In addition, the design satisfied the requirement to provide fish passes at all weirs and canoe ramps at Evesham and Chadbury weirs. Most of the funding was provided by the River Avon Weirs’Trust.
Stable Foams and Sludge Bulking: The Largest Remaining Problems (Abridged)
Authors: Wanner J.
Published: July 2007

The separation of activated sludge in secondary settling tanks is the crucial step in biological wastewater treatment from the point of view of both final effluent quality and operation of the aeration plant. The sludge‐separation problems of bulking and foaming are connected with an excessive growth of filamentous micro‐organisms in the biocenosis of activated sludge.

This paper (a) describes the methods which are used for the quantification of activated‐sludge separation problems, and (b) summarizes the design recommendations for bulking and foaming control.
Grey‐Water Reclamation for Non‐Potable Re‐Use
Authors: Surendran S. , Wheatley A. D.
Published: July 2007

Direct water recycling has become an important part of water conservation in the dry areas of the world and is now being seriously considered for the UK. This paper reviews current demands in large buildings and balances these against non‐potable re‐use. Work is also described on the development of a sustainable low running cost treatment unit. Results are presented from a 751/day prototype biological process operated with a synthetic sewage, which achieved a near potable standard at a cost of 25 p/m3. The design, performance and costings of a 40 ‘population equivalent’demonstration unit are also given.
The Effect of Regional Factors on Leakage Levels and the Role of Performance Indicators
Authors: Skipworth P. J. , Saul A. J. , Machell J.
Published: July 2007

In 1997, the Government introduced mandatory leakage targets for water companies, which were designed to (a) preserve water resources, (b) guarantee security of supply, and (c) promote efficiency within the water industry. It is intended that each target should reflect the individual situation of the company and that the targets should be achievable within reasonable economic constraints.

This paper examines the numerous factors which affect leakage levels and describes how these vary regionally. The evidence demonstrates that a company's level of leakage is dependent upon the local situation and that, at present, there is no basis for comparison which ensures equality in the stringency of leakage targets.
Computational Fluid Dynamics and the Design of Sewage Storage Chambers
Authors: Stovin V. R. , Saul A. J.
Published: July 2007

Recently in the UK, there has been significant interest in the design of combined sewer overflow chambers and storage tanks. This paper describes an extensive laboratory and computational fluid dynamics study into the hydraulic performance and sediment retention efficiency of tanks. The work has shown that (i) it is possible to predict the flow field which is measured in the laboratory using computational fluid dynamics, and (ii) a critical bed shear stress may be used to determine the extent of sediment deposition. Subsequently a bed shear stress model and the particle tracking routine in ‘FLUENT’have been used to compare the sediment retention efficiency of eight different chamber designs. The results showed that the length to breadth ratio of the chamber was the most important parameter to influence sediment deposition, and that changes to the benching and longitudinal gradient of the tank had minimal effect.
Predicting the Mean Annual Flood for Small Catchments: Experience in Northern Ireland
Authors: Gardner C. M. K. , Wilcock D. N.
Published: July 2007

The paper describes six alternative equations for predicting mean annual flood from catchment characteristics, developed in and subsequent to the UK Flood Studies Report and tested for ten small catchments in Northern Ireland. The most satisfactory equation was found to be one developed in the mid‐1980s for large catchments in the Province. Equations which were developed using small‐catchment data from elsewhere in the UK performed less well. The paper considers whether there is a real difference in the behaviour of small and large catchments in Northern Ireland, and examines alternative methods of estimating the mean annual flood in partly‐urbanised areas.
Fluvial Flood Forecasting
Authors: Cluckie I. D. , Han D.
Published: July 2007

This paper describes some of the latest developments in real‐time fluvial flood‐forecasting systems which utilise quantitative weather radar information. Rain‐gauge, flow‐measuring stations, weather radar and other sources of information are fully integrated by the real‐time flood‐forecasting system and provide flood warnings for civil protection. The systems have been commissioned in various regions within the UK and are undergoing continuous development in conjunction with the UK water industry and through close involvement with various European partners via the auspices of the European Union.
The Estimation of Flood‐Response Times from Digital Catchment Data
Authors: Marshall D. C. W.
Published: July 2007

The UK Flood Estimation Handbook describes a new approach to flood peak estimation and includes a volume which summarises developments in the rainfall‐runoff method since its publication in the Flood Studies Report in 1975.

One of the improvements has been the construction of a new unit hydrograph time‐to‐peak estimation equation. The handbook illustrates how information from digital datasets can be used to compute a number of catchment descriptors which, taking the place of information abstracted manually from Ordnance Survey maps, are introduced as independent variables. The new equation is obtained from an enlarged database consisting of 1822 rainfall‐runoff events which incorporate a greater variety of catchments than were used in the Flood Studies Report.

This paper (a) summarises the extent of the research, (b) outlines the steps involved, and (c) recommends an equation for estimating unit hydrograph time‐to‐peak from digital catchment data.
Hydraulic Characteristics of Wet‐Pulverised Municipal Waste
Authors: Buchanan D. , Clark C. F. , Ferguson N. S. , Kenny M. J.
Published: July 2007

Landfill technology must adapt to the changing demands of policy makers and waste regulators if it is to continue to deliver environmentally sound and efficient waste disposal. Among the more significant requirements that may fall to landfill designers is for the pretreatment of municipal solid waste and that the fill will rapidly stabilise. This paper reports on the key relationship between in‐situ density and the hydraulic characteristics of pretreated municipal solid waste. The paper also considers the practical significance of the research in relation to current UK landfill practice, and examines the viability of the flushing bioreactor.
Constructed Wetlands and Reed‐Beds: Mature Technology for the Treatment of Wastewater from Small Populations
Authors: Cooper P.
Published: July 2007

This paper reviews the design and performance of constructed wetlands for the treatment of domestic sewage. Horizontal‐flow systems have now become accepted for secondary treatment where only BOD and SS consents are required. However, in recent years there has been increasing interest in systems such as vertical‐flow and hybrid systems which are capable of achieving good nitrification. These systems have a greater and more reliable capability for oxygen transfer. As yet, there are only a few systems of this type in the UK, but the number is likely to increase. The paper describes the performance of (a) secondary and tertiary treatment systems, and (b) sludge‐drying reed‐beds.
Arsenic Removal from Groundwater in Conjunction with Biological‐Iron Removal
Authors: Lehimas G. F. D. , Chapman J. I. , Bourgine F. P.
Published: July 2007

This paper describes an investigation using biological‐iron removal for the elimination of arsenic (III). Groundwater was spiked with sodium arsenite and filtered through a pilot unit. As the water filtered through the sand, arsenic was retained on the iron oxides which were continuously produced by the bacteriological activity. Under specific aeration and pH conditions, both arsenic and iron were eliminated. This process can be used for the design of a full‐scale biological treatment plant.