Colour Removal in a Reservoir and the Dredging and Dewatering of the Deposited Waterworks Sludge

T he A lbert R eservoir of the Yorkshire Water Authority was built in the 1850s as the final raw water storage in the chain of impounding and storage reservoirs which feed Halifax, Brighouse, and Elland in West Yorkshire (Fig. 1).
This paper describes the problems encountered with increasing raw water colour since the mid1970s, the action taken to pretreat the water at the Albert reservoir prior to pressure filtration at the Thrum Hall Water Treatment Works (WTW), and the resulting problems with the deposited alum sludge in Albert reservoir.     

The Prevention of Oil and Chemical Pollution: Proactive Approaches in the UK and Canada

In the UK, various initiatives have been launched in an attempt to provide guidance on the occurrence and avoidance of oil and chemical pollution. Despite these efforts, oil and chemicals remain a major cause of pollution. In Canada, similar initiatives have been more successful due to a participative approach to campaign development and implementation. This paper compares UK and Canadian initiatives and identifies factors which led to the success of the Canadian campaigns.     

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.     

Managing the Impact of Tourism on the Environment

Tourism is now the world's largest industry, generating earnings of £285 billion/annum. In recent years, the tourism sector has become a significant contributor to the wealth of the UK and represents about 7% of the workforce. Greater mobility and more leisure time has led to greater car use, many more short-term movements of people, and increasing pressure on the transport infrastructure. Consequently, there is real concern about the effect of increased tourist activity on the environment and how the challenge of sustainable tourism can be achieved. This paper examines how the tourism industry is addressing that challenge by balancing the benefits of tourist activity without compromising the environment. In Wales, the Wales Tourist Board is committed to sustainable tourism, and its approach is offered as an example of achievement and how conflicting demands can be resolved.     

Reservoir Sedimentation and Colour Problems in Southern Pennine Reservoirs

A study of two major environmental issues in upland water management is presented. Discolouration and reservoir sedimentation are seen to affect water managers on different timescales and to different degrees. Rates of reservoir sedimentation, adjusted for empirically derived trap efficiency, are measured and found to be higher than previously believed. A link between sediments found within the reservoir basin and the generation of colour is described.     

Quality Control of Water-Treatment Chemicals

Quality control measures for regionally purchased treatment chemicals in Severn Trent Water Ltd apply from the point of manufacture through to their arrival and acceptance on a water-treatment works. This approach involves a formalized examination of the control systems of treatment chemical suppliers and the introduction of standard documented acceptance procedures at each treatment works. These measures are intended to not only provide a high degree of reassurance to customers, but to ensure that staff of Severn Trent Water are purchasing and receiving cost-effective materials which are of an acceptable quality in terms of active constituents and background contaminants, before use in the treatment of water     

A REVIEW OF THE EFFECTS OF SEWER LEAKAGE ON GROUNDWATER QUALITY

Exfiltration (of sewage into the ground from faults in ageing sewerage networks) has been recognised for many years but has never been quantified. It was considered that this leakage did not pose a groundwater-contamination threat because it was assumed that pathogens in sewage would either die off or be attenuated before reaching the groundwater level.
This paper identifies why sewers have faults that could allow sewage exfiltration where the sewer is above a groundwater resource. Because of a lack of UK data on sewage exfiltration, research work in Germany is discussed and analogies are made between the sewerage networks of the two countries.
Until recently, it has not been possible to positively identify sewage contamination of groundwater because of other pollutants and potential sources within an urban environment. The development of sewage-fingerprinting techniques has overcome these difficulties and provides conclusive evidence of sewage contamination of shallow and deep groundwater resources in researched areas. Studies of groundwater recharge and total solute loadings allow quantification of sewage exfiltration reaching the groundwater within the Midlands conurbation. The paper concludes that urban aquifers are potentially more vulnerable to microbiological contamination from leaking sewers than has previously been assumed.     

Meeting Standards for Lead in Drinking Water

During the last twenty years, the UK has made steady progress in the understanding of the 'lead in drinking water'issue and towards compliance with a lead standard which is more stringent than elsewhere in Europe.
Evaluating the needs for corrective action has not been straightforward because of the difficulties in characterizing the pick-up of lead from lead pipes throughout whole water supply zones. Survey methods have developed over the past twenty years as the behaviour of lead pipes has become better understood, but some ambiguities may still need to be addressed.
Information from Bristol Water suggests that compliance with a new lead standard of 10 μg/1 may be feasible by corrective water treatment in some zones, based on the already accepted practice of dosing with phosphoric acid, depending on how this more stringent standard is implemented. This view is also held by Anglian Water, based on their extensive experience with phosphoric acid dosing (without any significant problems) since the mid-1980s. Therefore total lead pipe replacement, at substantially higher cost, can likely be avoided in many zones.     

The Changing Picture of Water Consumption By Power Stations

Recent advances in open-cycle gas-turbine technology have resulted in station thermal efficiencies which are comparable with the large fossil-fired stations built in the 1970s. The combination of a steam cycle to the gas turbine culminating in the 'combined cycle gas turbine' station has led to even greater generating efficiencies. These advances in power-station design have led to reductions in water demand per megawatt of electricity generated. However, water usage still contributes significantly to increasing fuel efficiency in (a) the electrical generating process, (b) reducing atmospheric emissions from stations burning fossil fuels, and (c) utilizing gas turbines. Considerations arising from the competitive electricity market and wider issues of sustainability and environmental improvements, in general, suggest that water will continue to be required for power generation in the foreseeable future.