Cost-Effective Water-Quality Modelling of Potable Water Distribution Systems

Before privatization of the water authorities in England and Wales in 1989, future water companies were instructed to provide auditable proof of their investment requirements by the production of asset management plans.
With respect to distribution systems for potable water, asset management plan studies have established that unlined ferrous mains are often the main cause of complaints about discoloured water. It has also been found that the investment in water mains rehabilitation, which is driven by water quality problems, overshadows similar investment requirements driven by high burst rates and poor hydraulic performance.
This paper describes how certain techniques of water quality modelling have been developed and refined to provide a rapid, cost-effective method for identifying requirements for water-main rehabilitation.     

Asset Management Planning: Theory and Practice

In 1988, water undertakers in England and Wales were charged with producing asset management plans as a prelude to privatization. These plans had to provide an auditable statement with respect to the condition and performance of underground assets, with a view to defining and setting priorities for investment requirements.
Some water authorities were ill-prepared for producing the required formalized plans, resulting in variable confidence limits being placed on the identified investment requirements. A need existed to refine most plans, which was reinforced by a statutory requirement to update the asset management plans.
This paper deals particularly with water distribution systems and provides an insight into the production of asset management plans. A brief review of the current approach used by a certain major water plc, to update and refine their plans, is also included. The contribution of asset management plans to the effective management of distribution network investment and operation in England and Wales should not be underestimated and is equally relevant in Scotland.     

The impact of climate change on reservoir water quality and water treatment plant operations: a UK case study

A simplified climate change impact assessment tool (SCIAT) has been developed to address the specific needs of the water industry and provides a tool to translate climate change projections into ‘real world’ impacts. Its application is demonstrated in this study to assess the impacts of climate change on the reservoir water quality and water treatment plant (WTP) operations at Grafham Water in the east of England. The primary aim is to provide WTP operators with knowledge of the potential impacts and associated probabilities of occurrence of climate change, enabling them to make informed, risk‐based adaptation and planning decisions. Using a series of coupled hydrological and water‐quality models, it is likely that there will be a decline in average reservoir water quality. Climate change will also have an impact on WTP operations, but these will be manageable within the current operational parameters.     

USE OF GROUNDWATER AGE INDICATORS IN RISK ASSESSMENT TO AID WATER SUPPLY OPERATIONAL PLANNING

Groundwater residence-time survey results on 21 public water supplies in the chalk aquifer in southern England are compared with a previous Cryptosporidium risk assessment which was carried out on the same supplies for regulatory-compliance purposes in 1999. The results indicate that residence-time indicators could provide useful corroborative evidence for rapid recharge hazard - not only in those settings already identified by microbiological surveillance, but also in the more difficult-to-identify situation where potential rapid pathways have been identified but the bacteriological indicators are negative or ambiguous. However, groundwater-mixing processes under pumping conditions are complex, especially in the chalk, and will always require interpretation informed by an understanding of the local hydrogeological and operational setting.     

Perfluorooctane sulphonate in raw and drinking water sources in the United Kingdom

There has been increasing interest in the widely used perfluorinated chemicals such as perfluorooctane sulphonate (PFOS). PFOS has been shown to be toxic, persistent and bioaccumulative in the environment and is a focus for restriction within the European Union. Limited monitoring data, especially in the United Kingdom, are available for PFOS in environmental waters, and even less for its detection in drinking water. Data available in the United Kingdom indicate that PFOS contamination of environmental waters has only occurred following specific incidents. Monitoring of 20 raw and treated drinking water sites in England, covering four seasonal periods, showed that PFOS is not a widespread background contaminant of raw and treated drinking water in England. Low levels of PFOS (0.012–0.208 μg/L) were detected at four specific sites, which were at a higher risk for contamination. At three of these sites, where PFOS was detected in both raw and final drinking water, treatment processes [chlorination, ozonation and granular activated carbon (GAC)] did not appear to remove PFOS. The findings of this work are pertinent to risk assessments now required by the drinking water quality regulations.     

National Rivers Authority National Strategy and Planning for the Future

The protracted drought from 1988 to 1992 has focused attention upon the availability of water sources in England and Wales. The drought was most severe in the east and south-east parts of England, which also coincides with the areas having (a) the least available water resources, (b) the greatest forecast increase in demand, and (c) the majority of low-flow problems due to excessive authorized abstraction. Even with increasing attention being paid to demand management, there is a need to develop further water-resource schemes. Once local options have been developed it is likely that inter-basin transfers will be required.     

A geospatial approach to assessing microbiological water quality risks associated with irrigation abstraction

All crops that are eaten raw can present a microbiological risk to consumers. Disease outbreaks in the United Kingdom and United States have illustrated that ready‐to‐eat crops can be a vehicle for the transmission of gastrointestinal disease. Irrigation water has been implicated as a possible source of microbiological contaminants. Over two‐thirds of irrigation water applied to UK salad crops is abstracted from rivers and streams. Many of these are subject to a continuous input of faecal contamination from sewage treatment works as well as intermittent inputs from livestock and sewer overflows. In this paper, we show how geospatial techniques can help to assess the relationships between treated effluent discharges and abstractions and thus provide a new insight into local‐scale assessments of irrigation water quality. The extent to which the approach can inform risk assessments and decision‐making at the farm scale is demonstrated using a case‐study catchment in eastern England.     

Statutory Water Quality Objectives and River Water Quality

This paper summarizes some of the key issues which have been considered in developing proposals for a scheme of classifying river quality for the purpose of setting water quality objectives on a statutory basis. Particular attention is given to (a) the relationship between use-related and general water quality targets, (b) the role of biological assessment, and (c) the requirements of EC directives. Following widespread consultation on the proposals, it was concluded that a clear distinction should be made between sets of 'use classes'which would serve to set statutory water quality objectives (SWQOs) and a general quality assessment scheme which would be applied independently to assess trends and general progress over a period of time. Once the classification scheme has been established by the Secretaries of State through regulations, SWQOs will be introduced to river stretches in a number of 'pilot'catchments across England and Wales, following local consultation. The setting of SWQOs will provide the focus for local decision-making on what the appropriate level of water quality should be – taking into account the desired uses of rivers, what will be required to achieve them, and the associated costs.     

Investment Appraisal in the Water Industry of England and Wales

Since privatisation in 1989, the changing nature of the water industry in England and Wales has increased the need for effective investment appraisal. Previous research highlighted many aspects of the industry that could detract from the efficacy of conventional discounted cash-flow techniques, and found that an investment-appraisal technique must fulfil a number of criteria in order to overcome these difficulties. This paper examines a number of financial and strategic management techniques for investment appraisal, and assesses their suitability with reference to these criteria. It shows that, of the studied techniques, the 'balanced scorecard'appears to be most suited for use in the water industry of England and Wales.     

An investigation of complex saline groundwater problems in the Permo Triassic sandstones of North West England

Long standing saline intrusion and connate saline groundwater problems are being studied in the Permo Triassic aquifers of North West England. This multidisciplinary study is being carried out to provide data for the evaluation of aquifer management options for the protection of valuable water resources.Major and minor ion chemistry determined from pore waters depth samples and pumped discharges are being examined in conjunction with isotope data. Geophysical logging and deep penetration surface resistivity techniques are helping to delineate saline water bodies. Packer tests down to depths of 400 metres are providing information on aquifer properties and saline water movement.