The Lower Colne Improvement Scheme: Environmental Costs and Benefits

ABSTRACT The Lower Colne improvement scheme, on a river system to the west of London, was the first in the Thames region to give equal importance to environmental and engineering aspects in a feasibility study which was carried out in the early 1980s. This resulted in a scheme proposal comprising sixty elements of discrete work, rather than a continuous new channel or embankments, which reduced the impact on the environment. Many of these separate elements comprise environmental mitigation and enhancement features. This paper focuses on (a) examples of different types of scheme, (b) the environmental advantages and disadvantages, and (c) the costs of incorporating such features into flood-defence works.     

Strategic Resource Development Options in England and Wales

This paper describes the options which had to be considered for new water resources in the development of the † National Rivers Authority's water resource strategy for England and Wales. The options included interregional transfers, strategic reservoirs, and a range of unconventional schemes including aquifer recharge, effluent re-use, groundwater abstraction where levels are rising, desalination, and transfer by sea. The main options are described and comparative costs are presented.     

Fenay Beck Flood-Alleviation Scheme

The paper describes flood detention and channel improvement schemes which have been designed to alleviate the flooding of domestic and industrial properties to a 50-year standard of protection. Landscape architects were incorporated into the design teams to cover environmental aspects.
The flood-detention dam would have been constructed mainly of colliery waste, and the design of the concrete horseshoe spillway and stilling basin was checked using a 1 : 40 physical model. River regulation would be by an automatic vertical gate activated by downstream water levels.
Following planning refusal, a channel-improvement scheme was adopted, which is presently under construction. Reduction in valley storage increased downstream flows, necessitating the enlargement of an old brick and concrete culvert within the ICI works to ensure that there were no detrimental effects within their boundary. An increased benefit/cost ratio of 3.46, as compared with 2.55 obtained for the detention scheme, was partly due to the application of new standards.     

The Treatment of Weathered Crude Oil in Kuwait

During the Gulf War about 740 oil wells were blown up by the Iraqi forces, and the unburnt oil flooded from these wells to form oil lakes. This resulted in one of the largest oil slicks in the world, causing serious damage to the marine life in the Gulf region. The oil which is exposed to atmospheric weather over a period is called 'weathered crude oil feed stock', and it is important to treat this oil not only from the economical point of view but also to consider the environmental pollution which is created. The Government of Kuwait, represented by Kuwait Oil Company (KOC) has made its best attempts to treat this oil, and most of the oil lakes have now been cleared. The objective of this study is to report and evaluate different treatment methods and measures to control and manage these oil lakes.     

The Sirofloc Process at Redmires Water-Treatment Works

The first use of the Sirofloc process in an operational water-treatment works, outside Australia, was commissioned in 1988 by Yorkshire Water at Redmires, Sheffield. The plant represents a major advancement in the development of a new type of treatment process for drinking water.
This paper describes the new treatment process and the method and reasons adopted in developing a full-scale plant. The first four months of operation are reviewed, with particular attention to the water quality produced and the performance of the plant. Further areas for development in improving the performance of the process are identified.     

Measurements of Head Variations within Observation Boreholes and their Implications for Groundwater Monitoring

As part of several groundwater investigations of the Permo-Triassic Sandstone aquifers in north west England, a detailed measurement of piezometric heads and groundwater flow within observation boreholes was made which showed that vertical differences of groundwater heads persist within aquifers. A number of case histories of these studies are presented, which are used to consider the impact of head variations on typical groundwater level and groundwater quality measurements taken in observation boreholes, with a view to recommending design criteria for observation boreholes and groundwater monitoring programmes.     

A Replacement Outfall for Peterhead

The paper describes the design and construction of an outfall into Sandford Bay, Peterhead, on a highly-exposed stretch of the NE coast of Scotland.
The outfall forms part of a drainage system that was installed in the early 1970s to reduce pollution in Peterhead Bay and to accommodate increased flows from oil-related development. It replaces the original outfall, which failed in 1979 due to wave action.
Stability of the new steel-pipe outfall, which was installed by the bottom pull method, is ensured by burial within an excavated rock trench, backfilled and armoured with graded stone.
The exposed location of the site was demonstrated during construction work when bad weather and adverse sea conditions delayed completion by one year.
The paper concludes that the full significance of prevailing sea and weather conditions, and consequently reduced working 'windows', should be taken into account in the planning and programming of outfall work, to reduce the risk of damage to a partially completed and unprotected outfall.     

Risk management in safety critical areas

This paper examines the lessons to be learned from recent disasters. From these and other evidence it deduces good practice in managing risk in safety critical areas. It explains some methods which may be used to aid decision-making for implementing risk control measures. The paper uses examples drawn from the UK rail transport sector with specific reference to current BR practice.     

UK Drinking Water: A European Comparison

Introduction of the drinking-water Directive has resulted in a much more quantified approach to drinking-water quality. Increased attention from environmental groups and the media, together with occasional breaches of the limits, have resulted in a loss of confidence in the product. Infringements depend upon the stringency of the limits and the quality of available raw water. The UK is one of the few EC countries having to use a high proportion of surface water. The Directive has now been fully implemented in all member states, but information on compliance is poor. Only the UK and Ireland produce compliance reports. Published papers indicate that infringement problems exist throughout the Community, particularly for pesticides, nitrate, lead, coliforms and iron. Nevertheless, drinking water is of very high quality within the EC, and UK supplies compare very favourably with the rest.     

A Large-Scale Grid-Based Hydrological Model of the Severn and Thames Catchments

This paper addresses the issues of scale and appropriate model complexity for large-scale hydrological models. A grid-based hydrological model, which employs the UK Meteorological Office Rainfall and Evaporation Calculation System, is applied to the Severn and Thames catchments using a grid scale of 40 km, and is shown to reproduce the observed mean annual runoff over a 10-year period to within 6% with no prior calibration. The variation in the model performance is strongly correlated with the linearity of the annual rainfall/runoff relationship and a climate index. At the monthly scale, runoff routing becomes significant, and the introduction of a two-parameter routeing algorithm significantly improves the monthly runoff simulations giving efficiencies of 90% and 88% for the Severn and Thames respectively. The results provide guidance to climate modellers looking for efficient and robust land-surface parameterizations, and indicate the potential application of such a modelling scheme to water resource managers.