Ultra-Violet Disinfection of Sewage Effluents: A Pilot Study at Bellozanne, Jersey

In March 1990 a pilot ultra-violet disinfection plant was installed at the sewage-treatment works in Bellozanne, Jersey. The pilot plant was set up to test the ability of the process to meet certain defined objectives and, ultimately, to enable the island authorities to satisfy stringent water quality objectives in the receiving waters of St Aubins Bay.
The pilot study simulated an open channel installation using medium pressure ultra-violet lamps parallel to the direction of flow. The pilot plant was supplied by Trojan Technologies Inc.
The pilot study met its objectives and confirmed the design parameters for a full-scale plant installation to follow.     

Groundwater Model of Conditions in Liverpool Sandstone Aquifer

T his study considers the groundwater conditions for the period 1948–82 in the Permo-Triassic Sandstone aquifer of the Liverpool area. During this period, significant changes have occurred in the abstraction patterns and a new railway tunnel has been constructed below sea level in Central Liverpool. To understand the flow conditions within the aquifer, detailed studies have been carried out into the aquifer properties, the influence of rivers and tunnels, and the estimation of recharge. It is found that conventional rainfall recharge accounts for only one-third of the total recharge.
Numerical model solutions were used to check the adequacy of the understanding of the flow processes and the solutions have confirmed that the rising water levels in Central Liverpool result from high recharge and a reduction in abstraction. Having validated the model by comparisons with field data, the model was then used to predict the probable future water level changes.     

Managing and Engineering Rivers for the Benefit of Man

F rom earliest times flood, famine and drought have been scourges of mankind. River engineers alleviate floods, drain the land for agriculture, and conserve water resources. They construct engineering works, guide planners and developers, and provide warnings to minimize damage caused by storms over catchments and coasts. As the country becomes more developed, problems of reconciling conflicting interests require a flexible approach. This paper examines ways of providing the basic services in a climate of increasing public clamour for wildlife and landscape protection, and recreation.     

EYE-SORE: A Sewerage Agency Summary of Rehabilitation Experience

P ublic awareness of the importance of the sewerage network is inevitably highlighted when the system suffers malfunction. Associated with surface collapse or increased pollution to a local watercourse the effects are more widely felt, whilst even programmed work is not without significant environmental impact. With its history of deteriorating and failed sewers, the rehabilitation work already implemented and the introduction of a strategic sewerage policy, the paper outlines aspects of the City of Manchester's experience and effort to eradicate the consequential scars of its heritage whilst also looking to the future.     

Economic Optimization of Distribution Leakage Control

E vry WATER DISTRIBUTION system has an economic optimum level of leakage. To maintain that optimum level of leakage there is a corresponding optimum level of leakage control activity.
Despite much work on this subject, particularly in recent years with publication of DoE Report No. 26¹, many undertakers remain unclear about their economic optimum leakage level and how much effort is required to maintain that level.
This paper describes development of an economic model which attempts to quantify optimum leakage through measurement of parameters which should be readily available or obtainable.
The model was originally developed specifically for routine sounding. However, extension of the basic principles allows development of a general optimization theory. The paper then shows how the theory can be applied to optimization of district metering     

Coping with COPA II: Actions to Improve Effluent Quality

The paper outlines some of the actions taken by Severn Trent Water to achieve compliance with consent limits since the implementation of the Control of Pollution Act (Part II) in 1985.
Prior to and since 1985, Severn Trent Water has undertaken an extensive programme to analyse the reasons for failure and carry out remedial work. A major feature of this programme, which has been further stimulated by privatization, has been the need to reduce the lead time for carrying out improvements.
The paper discusses the means by which this has been achieved, including the introduction of the 'fast-track'initiative and the 'process matrix'.
Other aspects are outlined including initiatives to develop more robust processes, computerized work scheduling, extensive training programmes and best practice studies.     

Impact of the River Maine Drainage Scheme on Hydro-Power Generation

A comparison is made between pre- and post-drainage scheme river flows recorded on the River Maine, Co. Antrim. A method of using five-year reference periods has been applied to the mean daily flows to smooth and eliminate, as far as possible, variations due to climatic changes.
Any loss of energy production which might have been due to changes in river flow was examined for turbine installations at a factory at Cullybackey. The quantities of usable water, and hence potential energy production, were calculated for each of the post-scheme five-year periods and compared with a pre-scheme five-year reference period. Any potential loss was then represented by a depreciation factor. It was found that no measurable loss of potential energy production has occurred on the River Maine in the post-scheme period.     

Environmental Implications of Treatment of Coastal Sewage Discharges

The environmental implications of implementing the requirement for treatment of coastal sewage prior to discharge, which were put forward in an EC draft Directive on municipal waste-water treatment, are examined. In order to establish the current situation, the results of a national survey of coastal and estuarine sewage discharges are presented. A review of the impact of sewage discharges on the marine environment is presented in conjunction with an assessment of the impact of sewage-treatment processes on the land and in the air. These aspects are integrated into overall conclusions about net environmental impact. Finally, a decision-tree approach to the assignment of priority to additional action required at individual locations is developed.     

An Independent Perception of Regulation in Practice

The paper reviews the regulation of water companies in England and Wales since 1989 by reference to the historical regulation of utilities in these countries. It considers how comparative competition, service standards and charging arrangements are developing. Particular mention is made of the debates over rates of return and household metering. The conclusion is that regulation, to be effective and appropriate, must be capable of evolution.