Abstract: The paper deals with the evaluation of a project that a Water Utility implemented in its water distribution network. The project included installation of PRVs and launching of a Public Awareness Campaign, in order to decelerate the brake rates of the various types of pipes (by dividing the whole system into pressure zones); and to decrease the urban water consumption. The project is being evaluated (ex-post evaluation) based both on its environmental and financial (money savings) impacts. Break rate forecasting models are developed, using the Water Utilityâs records, in order to determine the optimum replacement time of the pipes, based on the Present Value of all types of costs related to a pipe break. The results are compared to those of similar projects implemented in other networks having more or less the same characteristics. The interventions involved are presented and their consequences regarding the water savings are evaluated in economical terms, using a cost-benefit analysis. Finally, suggestions regarding the management of the specific network that can also be widely used to water delivery networks of other metropolitan cities are stated.
Abstract: The growth of investments related to the renewable energy sources sector rendered them profitable and competitive towards respective conventional ones, making imperative the need of examining their economic viability as investment drawings. The present study checks the feasibility of a small hydropower plant located in a small highland village, Vatsounia, Greece, utilizing the waters of a local river. The water used to produce electricity returns to the river in order to be used to irrigate cultivated land. The whole project combines high profitability while being environmental friendly. The special characteristic of this project is that a Public Base Company was established to run it. Regarding its partnership scheme, the Community itself holds 35% of the stocks, and the rest 65% has been given to the local residents (treated as individuals) with an upper limit of 2% per stockholder. This stock distribution practice is typical for a Public Base Community Company. The electricity produced is being sold directly to the Public Power Corporation according to the national law. The resulting revenues of this investment provide an important income for the local community and its shareholders. The case study presented proves that a medium-scale hydropower plant can be financially viable while being compatible to the sustainable development of the environment
Abstract: The paper presents some of the most common operational problems in water pipe networks, studied in the water distribution system of Athens, the capital of Greece. The study, which took place from 1995 to 2000, concerning individual pipes of a network with a total length of 7,000 km, was based on the leakage and pipe break records kept by Athens Water Utility. The main outcome was an easy-to-use troubleshooting manual for handling operational problems in water pipe networks. This troubleshooting manual, as a product of applied research, is a knowledge base that can form the basis of an expert decision support system for detecting, identifying, studying and solving the problems that occur in a water distribution system.
Notes: empirical study, operational and structural failures, water pipe network, troubleshooting manual
Abstract: What should System Managers prefer? Systems that never fail or systems that remain safe during a failure? The present paper tries to give an answer to this dilemma by presenting a methodology that hierarchically analyses the possible preventive maintenance actions in a water system. The whole attempt is based on appropriate indices that assess the performance level of the system, before any action is taken. This is accomplished through a technico-economical analysis that takes into account all kinds of costs referring to the repair or replacement of trouble-causing parts of the system. The methodology can be implemented to any kind of system (e.g. waterworks infrastructure concerning surface or groundwater resources). The present paper deals with a water supply network in order to present the suggested methodology.
Abstract: The water networks must be fail-proof or must remain safe during a failure? What do water system managers must try to achieve? The present paper introduces a methodology for the hierarchical analysis (in time and place) of water supply networks preventive maintenance policy, using water supply system performance indices. This is being accomplished through a technico-economical analysis that takes into account all kinds of costs referring to the repair or replacement of trouble-causing parts of the water supply network. The optimal preventive maintenance schedule suggested by the methodology is compared with the empirical-based maintenance policy applied in Athens water supply system.
Abstract: A detailed presentation of residential water use conservation techniques takes place in this paper. Its main goal is to present, as clear as possible, the operational methods-measures that are included in an integrated residential water use conservation program that is adopted-implemented in a rapidly developed area under water shortage conditions. The implementation steps and results of a urban water pricing policy program that was adopted in Athens, the capital of Greece, are finally being presented to verify its practicable character and effectiveness.
Abstract: The water resources in Northern Greece have been severely damaged due to the lack of a long-term water resources management plan, the prolonged dryness and their uncontrolled exploitation for agricultural and industrial uses. A management plan, considering environmental, economic and social factors, based on the principles of the holistic approach and the sustainable development of the total ecosystem, is being presented here, to protect and restore the water resources of Northern Greece
Abstract: The methodology introduced in the present paper, based on regression analysis of leak and breaks data records, is being used to determine the break-age functions of the pipes in a water delivery system with poor break data records. An alternative way to overcome this problem is being presented, by checking out the probable correlation between the records of leaks and breaks, based on the fact that both failures are being affected, more or less, by the same parameters, like the quality of the supplied water (e.g. aggressive water, oxygen content, natural lining layer), the condition of the soil, the pipe bedding conditions, the external loads, the climatic parameters, the erosion due to water flow behavior and the internal or external corrosion conditions. The whole idea came up from the thorough analysis of these parameters that took place in previous works (Kanakoudis 1998; 2001). The present paper, considering the whole problem as a âblack boxâ, succeeds to complete the breaksâ records using the respective (in time and place) leaksâ records in the case study of Athensâ water delivery system.
Abstract: The methodology that the present paper introduces, calculates the optimum replacement time for the pipes of a water network. This is being done through a technico-economical analysis that takes into account all kinds of costs referring to the repair or replacement of trouble-causing parts of a network. The applied methodology uses the Present Value method of economic analysis and suggests alternate ways to specify the models of break rates for the various kinds of pipes. This goal becomes possible using the - proved to exist - strong relation between the leaks and breaks that occur in the water pipes. Finally, the methodology presents a way of calculating the optimum replacement time for the pipes of a water network, by taking into account the water flow velocities (standard values and variations) into the pipes.
Abstract: The present paper is trying to implement the IWA standard international water balance for the case of the distribution network of the city of Larissa. Some of the performance indicators are also calculated and analysed. The goals of the study are to develop the IWA standard international water balance, calculate performance indicators and assess them in relation to other national and international data given by the bibliography. The final aim is to propose techniques (PRVs etc.) introduced to other Water Utilities internationally in order to minimize water losses.
Abstract: Water conservation in urban areas under water shortage conditions is not just a prospective but the only way to sustainability. When a Water Utility manager is called to decide whether a water conservation project, based on implementing appropriate water pricing policy, network upgrading measures and Public awareness activities, will have the desired results being cost-effective at the same time, has to relay on the projectâs ex-ante evaluation. This is actually a blue print based mainly on assumptions, increasing his hesitations and second thoughts. The projectâs ex-post evaluation is the only way to judge whether its approval was a wise think to do or not. Ex-ante evaluation is what is available; ongoing evaluation is usually a failure-correcting process; ex-post evaluation is what is needed. But who can fast-forward the time? Experience form projects implemented in networks having similar characteristics can be used as the most-desired time machine. The paper shares this kind of experience from the ex-post evaluation of two case studies in Greece (Athens and Thessaloniki). In Athens the project included the implementation of an aggressive Water Pricing Policy, while in Thessaloniki the project included the installation of PRVs to form DMAs. Both of them included Public Awareness Campaigns.
