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Demonstration Activities for the Reduction of Wate.. (RAKWANET)
Demonstration Activities for the Reduction of Water Losses and Preservation of Water Quality in Over-dimensioned Water Distribution Network in Rakvere Town, Estonia
(RAKWANET)
Date du début: 15 sept. 2001,
Date de fin: 15 sept. 2003
PROJET
TERMINÉ
Background
The Water Framework Directive and the Directive on Quality of Water Intended for Human Consumption set requirements for the quality of drinking water and the reduction of the environmental burden of economic activities on groundwater.
Rakvere is the biggest settlement in the Pandivere National Water Protection Area karst landscape, which is the main groundwater formation area in Estonia. Because of the poor condition of the water supply network and sewage pipes, dating back to the Soviet period, and bad ground conditions (karst, cracks, tectonic faults), waste water infiltration poses big risks to the quality of groundwater.
Due to the poor condition of old water distribution networks, water losses in the network were significant (up to 35 percent). A new water treatment plant was opened in 2001 and attempts were made to reduce water losses. The new water treatment plant resulted in a decrease in the velocity of water flow in the degraded pipelines, reducing the quality of supplied water. A comprehensive plan was needed to reduce water losses in the over-sized and degraded distribution network whilst preserving the quality of drinking water and protecting groundwater.
Objectives
The main objective of the project was to prepare a comprehensive and integrated plan for the reduction of water loss from over-sized and degraded water distribution network in Rakvere town, whilst preserving the quality of water supplied to consumers and ensuring protection of groundwater. The wider aim of the project was to ensure a safe water supply in the future without any negative health impacts, and in quantities and qualities that correspond to future demand and Estonian and EU legislation.
The project set out to close all separate old wells in the town and to supply water through the new water treatment plant. During the demonstration project it was planned to carry out all necessary activities to solve the problem of preserving water quality at requisite levels, when water flow will be reduced due to the reduction of water losses. The project aimed at addressing the goals of the Water Framework Directive, the Drinking Water Quality Directive (98/83/EC) and a number of Estonian legislative acts addressing issues of water consumption and protection.
Nine main activities were to be undertaken:
1. Design and set-up of the technical database using Access software for detailed logging of water supply, sewage network and water consumption data. The database is designed to be used as an engineering, administrative and management tool for planning and decision making.
2. Leak detection and flow measurements in the water distribution network and inspection of valve chambers to determine the need for replacement of valves.
3. Creation and calibration of a computerized hydraulic model of the water network to determine the best technical and economic solution for the water supply network.
4. Design of a water loss control and management system and a remote control system for the continuous flow and pressure measurement and regulation.
5. Reconstruction of valve chambers for closing during the flushing, installation of pre-fabricated chambers with inductive water meters and pressure meters.
6. Cleaning of the water distribution network using mechanical ('eco-pig') and hydro/pneumatic (air and water) technology. The main purpose of this activity was to carry out cleaning of ca'30 km pipelines using two alternative methods, to increase the quality of supplied water and to demonstrate new and modern techniques of cleaning of water pipelines.
7. Reduction of hazards to the ground water quality by
- closing of five old ground water wells with depth from 105 to 285 m.
- mechanical cleaning of 9,10 km of sewage pipelines
- CC-TV inspection of sewage pipelines
- preparation of a renovation action plan for the sewage pipelines
8. Setting up measures for the improvement of operation and maintenance of the water supply system for the reduction of water loss and preservation of water quality.
Results
The project worked towards a full implementation of EU legislation: WFD 2000/60/EC; 80/778/EEC and 98/83/EC on drinking water quality and 80/68/EEC on ground-water quality. The project also addressed the 6th Environmental Action Programme by integrating environmental concerns into other policies (water and sewage management; Article 2.2 of the 6th EAP) and by ensuring the sustainable use and high quality of our water resources (Article 5.6. of the 6th EAP, and Water Framework Directive).
Having carried out the planned tasks, the project succeeded in significantly improving drinking water quality (iron content), bringing it to the level required by Estonian drinking water standards. By closing old wells, an important step to reduce the leaking of pollutants into groundwater was taken. By introducing a comprehensive monitoring system, including a technical database for the registration of water supply and consumption and sewage network, leak detection and flow measurements and creation and calibration of computerised hydraulic model of water network, the project has provided tools for planning future actions for controlling the water supply, the quality of drinking water and reduction of hazards to the ground water. For more efficient detection of leakages, the system was designed for water loss control and management.
Consequently, the time taken to detect leaks decreased from 5-6 days to 2-3 days. Water losses were decreased from 37% to 21% of total extraction. The foreseen cleaning of water distribution network, originally including the comparative action of using eco-pig (mechanical) and âair-waterâ (hydropneumatic) methods, was only carried out partially. The eco-pig method proved to be too expensive and did not address the projectâs objectives and was consequently excluded. To sustain the projectâs results, the CCTV-inspection and mechanical cleaning in the sewage pipelines was carried out to develop a renovation action plan for sewage pipelines.
As a final outcome of the project, the programme for improvement of operations and maintenance of the water supply system and a water loss manual were prepared. Having carried out the activities, the project demonstrated a new efficient way of addressing the current problems in water supply and sewage systems, typical to the settlements in former Soviet countries, whilst bringing the quality and quantity of drinking water into step with EU water policy and national legislation.
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