Accounting for Polycyclic Aromatic Hydrocarbons in Public Water Supplies

Asset management plans were prepared in 1989 and 1994 by water companies in England and Wales for submission to the Office of Water Services. These plans constituted the financial programming required by water companies to meet specified standards of service, particularly with respect to water quality. Detailed studies have previously established that problems associated with iron from unlined ferrous mains, particularly in soft water areas, is often the main cost 'driver'for water distribution investment. However, many of the so-called unlined iron mains were treated with a coal-tar pitch lining for corrosion protection before installation, and residues of this painted lining can give rise to unsatisfactory levels of polycyclic aromatic hydrocarbons in drinking water.
The paper describes how desk-study research, followed by the development and application of a modified 'focused downstream series sampling'water-quality modelling technique allowed polycyclic aromatic hydrocarbons to be accounted for in two water company asset management plan submissions. The paper also raises a number of fundamental implications with respect to the occurrence of these carcinogenic compounds in drinking water.     

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.     

Quality assurance and quality control practices for rehabilitation of sewer and water mains

As part of the US Environmental Protection Agency (EPA)'s Aging Water Infrastructure Research Program, several areas of research are being pursued including a review of quality assurance and quality control (QA/QC) practices and acceptance testing during the installation of rehabilitation systems (USEPA 2011). The objectives of this research effort were to collect, analyze and summarize information on the installation and QA/QC practices for the trenchless rehabilitation of sewer and water transmission mains. In addition, consideration was given to practices related to water service lines, sewer service laterals, force mains, siphons, sewer manholes, pumping stations, associated wet wells and other appurtenances. This review was accomplished primarily by conducting interviews directly with rehabilitation technology vendors, design engineers and water and wastewater utilities that have a track record of using trenchless rehabilitation technologies within their network. This paper provides an overview of how QA/QC issues have been handled in North America for trenchless rehabilitation technologies.     

Introduction of the leak-before-break (LBB) concept for cast iron water pipes on the basis of laboratory experiments

Failure of cast iron water mains in Australia is a common occurrence. Water utilities are seeking solutions to optimise the renewal and rehabilitation of ageing cast iron critical water mains (diameter ≥ 300 mm). Failure pressures of three large-diameter cast iron pipe specimens (600 mm in diameter) were tested. A large corrosion patch was machined onto each pipe section to initiate pipe failure. A large corrosion patch and significant reduction (>90%) of pipe wall thickness were needed to fail the tested pipe specimens. All three pipes under test exhibited leaking before bursting, indicating that the concept of leak-before-break (LBB) could be used for pipe failure prevention. In addition, LBB provides valuable information that could be added to the pipe asset database to make better management decisions on repair or replacement along with all other asset information. The study also found that small corrosion patches (<50 mm) with low remaining wall thickness may cause pipe leaks, but are less likely to cause major pipe bursts.     

Strategic policy analysis for infrastructure rehabilitation using system dynamics

Recent requirements for sustainable development and increasing trend for public–private partnerships (PPPs) have added additional complexities to the policy-making process in the infrastructure management domain. To support policy analysis, this paper presents a system dynamics (SD) model to analyse the impact of different strategic policies (e.g. budgeting, PPP involvement) on infrastructure serviceability, backlog accumulation and sustainability. The proposed model has been implemented on a network of school buildings from the Toronto District School Board asset inventory. Four sets of experiments with different policy scenarios over a 50-year strategic planning horizon have been conducted to investigate policies related to rehabilitation, budget distribution, government investment and PPP involvement. The proposed model was implemented on a commercial SD software incorporating all the dynamic interactions among the strategic parameters. The experiment results show that the model works as a practical decision support tool that enables asset managers to test the effectiveness of various strategic policy scenarios on long-term infrastructure performance.     

Data acquisition and analysis for water main rehabilitation techniques

The ability to regularly deliver safe drinking water is a constant challenge to municipalities worldwide. In Canada, the replacement/rehabilitation cost of water mains is estimated to be $28 billion (1997–2012). Therefore, selecting cost-effective repair and/or rehabilitation scenario(s) is essential to optimise the quality of existing water mains and minimise unnecessary rehabilitation costs. The research presented in this paper identifies several rehabilitation methods for water mains, which are classified into three main categories: (1) repair (i.e. open trench, sleeves); (2) renovation (i.e. slip lining, cement mortar lining, epoxy lining, cured in place pipe (CIPP)); and (3) replacement (i.e. pipe bursting, micro-tunnelling, horizontal directional drilling, auger boring, open cut). Due to complexity, scarcity, and enormity of data required to perform life cycle cost (LCC) and select the cost-effective scenario(s), the research presented focuses on LCC data acquisition and analysis. Data were collected from contractors and municipalities in Canada. Rehabilitation decision trees were developed as a preparation step for future LCC implementation. Breakage rate analysis was successfully developed to predict the intervals of various rehabilitation alternatives. The research presented is relevant to researchers and practitioners (municipal engineers, consultants, and contractors) to prioritise pipe inspection and rehabilitation planning for existing water mains.     

Water mains renewal planning framework for small to medium sized water utilities: a life cycle cost analysis approach

For the last few decades, concerns have repeatedly been raised about deteriorating water mains in Canada. Small to medium sized water utilities are generally impacted more due to lack of technical and financial resources. This paper presents a user-friendly life cycle cost (LCC) analysis-based decision support tool to help these utility managers to prioritize water mains rehabilitation or replacement (R/R) strategies. The deterioration curves for water mains of different materials and sizes have been developed based on their likelihood of failure. The proposed model is implemented for the water supply network of City of Kelowna (Canada). It compares the costs of various R/R scenarios for each pipe over its life cycle and suggests the most cost-effective decision to the managers to efficiently allocate their limited resources.     

Decision support model for selection of rehabilitation methods of water mains

The deteriorating condition of water mains in Canada and US calls for rehabilitation strategies that accounts mainly for budget and level of service constraints. These water mains have received ‘D’ grade in the two countries. Decision support models can assist decision makers regarding when to rehabilitate and whether to repair, renovate or replace section(s) of water mains. The literature indicates that decision models should account for life cycle cost, uncertainty, long-term planning, targeted levels of service and budget constraints. The objectives of this paper are to: identify and group rehabilitation methods, present decision support model to rank and select most suitable rehabilitation method(s), and study the impact of rehabilitation methods on the functional and structural performance of water mains. The developed decision support model accounts for life cycle cost of each competing scenario along with the associated uncertainty. The model, unlike available models, can effectively account for vagueness, qualitative assessments and human judgment associated with input data. A case study of a water main network was analysed in order to demonstrate the use of the developed model and to illustrate its essential features. The results obtained indicate that the model can support the generation of well-informed decisions in a timely manner.     

Water industry asset management: a proposed service-performance model for investment

The water industry in England and Wales has developed over the last century, from small organisations serving local communities to large integrated companies in private ownership, overseen by a government regulator. Asset management practice has developed greatly in the 17 years since privatisation, with companies able to plan their operations and investment as they believe appropriate for the provision of customer services, subject to justifying their plans to the economic, quality and environmental regulators. Investment has flowed into the industry to replace deteriorated assets and to improve the quality of drinking water and rivers. The asset base is complex and, with a replacement value of approximately £231 billion at the 2002–2003 price base index suitable approaches are required to ensure that both the water service and the sewerage service are delivered at the most appropriate long‐term cost. The 2004 UK water industry price review was supported by the introduction of a Capital Maintenance Planning Common Framework to help companies understand and explain their maintenance investment requirement. In this paper, a service‐performance model is proposed to improve managers' understanding of the way in which businesses and the environment change over time, taking account of maintenance and other strategic requirements. Although developed with the water industry in mind, the model is equally applicable to other asset‐intensive industries.     

Rural water asset management practices in Ghana: the gaps and needs

This study evaluates primary and secondary data from two districts to assess the status of asset management practices, and to examine requirements for improved asset management. Asset inventory data shows that asset management practices in the districts are currently poor, leading to high rates of nonfunctionality and low service levels. The existing ‘fix on failure’ approach to water systems’ repair has become a common practice. However, many repairs which relied on ‘fix on failure’ were found to have delayed, often due to the length of time it takes to mobilise financial resources from ‘post‐paid’ water users. This paper contends that without an improved asset maintenance, system it is likely that rural water systems in Ghana will continue to provide unsustainable services. The Findings demonstrate that improving the current asset management practices is dependent on human and financial resources, access to timely water service monitoring data at district levels, and planning and budgeting regime to reflect life cycle costs of water systems.     

State of technology for renewal of sewer force mains

This paper presents the results of a review of the state of technology for renewal of force mains. Force mains are critical components of many sewer collection systems with significant environmental and cost consequences for failure. The review identified several needs, including the need for rational and common design approaches for rehabilitation systems, quality assurance/quality control procedures, and better practices for operation and maintenance. The difficulty in assessing the condition of sewer force mains, leaving many owners with questions about the integrity of their systems, and the limited amount of technologies available for renewing a deteriorated main, has limited the amount of renewal work in the past. Most of the renewal activity has involved complete replacement of the force main. As the nation's force mains age further, greater emphasis must be placed on finding cost-effective ways to renew these critical assets. Fortunately, new products and technologies are now emerging for condition assessment, as well as rehabilitation. Some newer methods developed for gravity sewers and water distribution systems are being adapted for use in force main rehabilitation but design and performance data gaps remain to be filled.     

Experience of Cast-Iron Mains Rehabilitation in the Gas Industry

Since 1987 British Gas plc has undertaken an extensive programme of medium pressure (up to 2 bar) cast-iron mains replacement in urban locations, using a variety of rehabilitation techniques.
This paper describes the experience of North Thames Region of British Gas plc, over the period 1987–1991, when the rehabilitation of over 230 km of mains was undertaken in the size range 300–460 mm.
The techniques which were used favoured medium density polyethylene pipe wherever possible. However, about 100 km of rehabilitation was undertaken using hoselining, usually where mains were larger than 460 mm dia., or where aboveground access was restricted, or if the mains configuration included many changes of direction.
This paper deals with (a) various aspects of operating rehabilitation contracts from a public utilities viewpoint, (b) the special factors relating to the inspection and testing of hoselined mains including factors found to contribute to failure, and (c) some of the controls that have been introduced to improve reliability of rehabilitation systems.     

Sewer asset management – state of the art and research needs

ABSTRACT

Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas.     

Assessing the influence of exogenous and quality of service variables on water companies´ performance using a true-fixed stochastic frontier approach

ABSTRACT

Improving the cost efficiency and quality of service across time corresponds to two important targets for regulated water companies. Following a pioneering approach, we have evaluated the influence of a set of exogenous and quality of service variables on the English and Welsh water companies’ costs over the period of 1996–2009. A true-fixed effects stochastic cost frontier model was applied since it also allowed computing of the productivity change of the water companies and their drivers. Results have shown that quality of service has an influence on water companies´ costs. This issue is very relevant for bursts in water mains since investments in reducing them will lead to a reduction in the water supply interruptions and water losses. Results of this study illustrate the importance of developing long-term planning investment programmes in the water industry.     

Using optimisation for integrated water network management

The water industry has undergone radical change in the late 1980s and changes continue apace. We have been, and will continue to be, under increasing pressure to reduce costs and increase service within a framework where regulations are becoming tighter and demanding more information to achieve and substantiate performance. The major challenge will lie with the leaders of the industry. They have to achieve the right attitude, management technique and technical excellence to meet the requirements of change and to create adaptable organizations that can manage the challenges of change in a positive and proactive way. Cultural change has started but has a long way to go. We must overcome the traditional attitude of many water suppliers, which has typically been one of the ‘professional stewardship’ of a resource in which they supply water in the way they believe to be best. This must change and is changing to a more commercially minded management which is ‘customer centred’ rather than ‘product centred’. We must realize that our organizations manage a complex asset base which has to work towards strictly defined objectives of service quality, operational efficiency and regulatory requirements, all of which, as time goes on, are influenced more and more by substantial external forces.     

Use of Soil Maps to Predict the Incidence of Corrosion and the Need for Iron Mains Renewal

The requirement for revised asset management plans from water-supply companies and the need to prioritize the renewal of buried water-supply pipework has stimulated an interest in the spatial distribution of corrosion risk and intensity. This paper reports how the relationships between soil corrosion and the spatial distribution of soil types, as displayed on soil maps, can be combined to predict the likely incidence of aggressive soils and thereby identify those water mains which are most likely to need early replacement. The concept is illustrated by a project supported by Portsmouth Water plc.     

Simulation-based life cycle cost modeling and maintenance plan for water mains

Life cycle cost (LCC) is an essential approach to decide on alternative rehabilitation strategies for infrastructure systems, such as water mains. The research presented in this article identifies several rehabilitation methods for water mains, which are classified into three main categories: repair, renovation and replacement. A simulation-based LCC (SLCC) model is developed to compare different rehabilitation scenarios/alternatives for various types of water mains (i.e. cast iron, ductile iron, concrete, polyvinyl chloride and asbestos cement). Results show that ‘open trench’ and ‘slip lining’ are the most appropriate methods for the ‘repair’ and ‘renovation’ categories, respectively. However, the most suitable method for the ‘replacement’ category is ‘pipe bursting’ for pipe diameters less than 750 mm (<30″) and ‘open cut’ for pipe diameters greater than 750 mm (>30″). A rehabilitation plan is developed based on the SLCC results. This plan recommends repairing pipes using ‘open trench’ until the breakage rate reaches 0.5 breaks/km/year, then, replace the pipe beyond this threshold. Based on the designed SLCC model, web-based software is developed to determine the optimal rehabilitation scenarios. The developed model and software help academics and practitioners (e.g. municipal engineers) to predict the suitable new installation and/or rehabilitation programs as well as their corresponding costs.     

Evolution of research on water leakage control strategies: where are we now?

ABSTRACT

This study provides an overview of the 21st century research trends for water leakage control strategies that focus on pressure management, active leakage control, pipe rehabilitation, asset management and District Metered Area (DMA) design. The biggest contribution comes from the research team in Italy, whilst the most active researcher is based in Greece. Research in this field has gained momentum from 2008 although a couple of studies have been conducted since 2000. Control strategies are receiving attention not only from academia but also from industrial players who are looking for technological advances by collaborating with academic institutions in research and development. The main strategy to reduce water leakage is the pressure management of water distribution systems using optimal settings of a pressure reducing valve installation. Despite available technologies, the commitment from the government, the water operators and the local consumers are the most important criterion for the effective implementation of water-leakage control strategies.     

Water Quality and Management Strategies in London's Docklands

Regeneration and changes in land use in London's Docklands have resulted in new water quality requirements. Areas previously occupied by docks now form part of redevelopment projects which have made a feature of the water.
The paper describes a project to provide water that is aesthetically pleasing and of a quality suitable for water contact recreational activities.
An extensive programme of water sampling and analysis was carried out to gain an understanding of the processes affecting water quality, including the monitoring of algal growth. The river is the main source of nutrients in the docks, which results in large concentrations of algal biomass and bacterial contamination. The principal strategy is to limit light via artificial mixing systems supplemented by limiting the inflow of nutrients from the river.
The results from the water sampling programme have been used to build a 3D computer model with a supporting graphic information system to attain (a) qualitative evaluations of management and development options, and (b) short-term predictions of changes in water quality.