Forslag til møteplan

Introduction

The Quality Water Project in the region of Drammen (the GVD project) is based on cooperation between nine municipalities in the region of Drammen in southern Norway.

The focus area of cooperation is water and sewerage projects where there are mutual interests beneficial for the participating municipalities
The cooperation itself is unique in a Norwegian context (Moen et al, 2008)

The region of Drammen has about 170.000 inhabitants. 150.000 have public water supply.

Figure 1: The region of Drammen (GVD) – Norway

The total water production is about 24 million m³ of water/year and there are about 1500 km of public water mains. The water production equalises to 400 l per capita per day.

The project is a result of a common master plan for water supply in the region, initiated by the municipalities and Glitre Water Works in 2004 (The municipalities of the Drammen region , 2004). The major topic to be addressed in the period covered by the master plan is reduced water demand and increased leakage control.
As indicated in Figure 2, the master plan forecasts that the capacity of the water source will be exceeded in 2035 if the increase in population continues, and no further actions are taken to reduce the water loss and the demand for water.
Figure 2: Expected growth in water production, with expected growth in population and no action is taken to reduce the water losses and the demand for water. (Master Plan 2005)
Investigations indicate that the amount of water losses in the distribution network of the region amounts to about 50 % of the total production.
In order to avoid costly investments in new water resources, with all the provisions and restrictions that might follow from this, on the use of the resource and the neighbouring land, it was decided to reduce the water losses and the water demand.
The target to reach is: “Stabilising water demand on the level of year 2004”. To accomplice this, two targets have to be reached: 1) A reduction in water loss from 50 % in 2004 to ≤ 30 % in 2020. 2) All customers must have water tariffs based on meter reading of water consumption no later that 2013. (Currently about 60 % of the customers have water meter)
The general strategy for water loss control follows the four basic methods recommended by IWA (Farly & Trow, 2003). 1: Active leakage control. 2: Infrastructure management. 3. Speed and Quality of repair. 4: Pressure management.
The work so far has primarily focused on active leakage control. 83 district metered areas (DMAs) are established using more than 100 district water meters (whereof about 25 are new). Two leakage control teams are established, using the latest technologies in noise loggers, leakage noise equipments and correlators.
I order to also focus on infrastructure management, especially the rehabilitation of water mains, a new project was started: How to select the right water mains for rehabilitation?
During the last decades, selecting water mains for rehabilitation traditionally has followed either of two approaches. 1) Rehabilitate water mains when another infrastructure needs rehabilitation. For instance sewers, road work etc. 2) Rehabilitate water mains when the number of leakages makes it obvious that rehabilitation can not be avoided. Following these strategies have resulted in too low renewal rate and thus an overall deterioration of the water distribution network, and an increase in the number of leakages and water loss.
Therefore, the GVD project decided to develop a tool that can support the engineers in selecting water mains for rehabilitation in a more sofisticated way, taking into account not only the leakage frequency, but also the probability for a new leakage to occur and the consequence of a leakage.