Flooding in Komarken

During the autumn of 2014, the Municipality of Kungälv was faced with considerable problems with old and dilapidated sewers in a couple of residential areas. These areas were affected by cellar flooding over a period of time and the situation grew more acute with each passing day. One of the areas most affected was the district of Komarken. Owing to the poor state of the sewers, a number of basements in the area were flooded. The municipality thus needed to take a strategic approach to the issue, a single measure to deal with the problem: a rapid, effective, long-term sustainable solution. The need for an effective solution eventually led to the municipality of Kungälv and Aarsleff initiating cooperation to resolve the situation.

“Relining is a tremendously effective method. Previous projects we have been involved with have taken years to complete. Residents had to put up with excessive noise, difficulties with access, puddles and dirt, all leading to complaints and dissatisfaction. This time we’ve been able to avoid complaints and the renovation has been extremely time effective.” Annelie Svensson, water and sewerage engineer, municipality of Kungälv


Areas where rehabilitation solved the problem

The rehabilitation work started with a thorough planning and surveying phase. In collaboration with the Municipality of Kungälv, Aarsleff collected the relevant drawings and, with the help of IRG Rörinspektion, filmed all the conduits in the area to get a complete picture of the situation. Then an overall assessment of the situation was made and calculations for the forthcoming work drawn up. It turned out that most of the conduits were in need of renovation and that the best solution was to take a comprehensive approach, proactively providing quality assurance for the future. Main pipes, service pipes and manholes were all successfully renewed. Property owners helped fix conduits on their land, which contributed to the successful result in the area.

Instead of just fixing the pipes that were damaged and causing problems, priorities and plans were drawn up on the basis of the respective pipelines’ needs for renovation. That is to say that when a stretch of pipeline needs fixing – as in this case – the whole stretch is renovated and no small sections are left out. If sections are left unrenovated, it often means having to come back again soon. Relining is an effective method, making it possible to renovate pipelines without having to dig up whole streets and gardens. Komarken was thus transformed in just a few days from an area with pipelines in a very poor state to an area with pipelines that are good as new again. In all, around 4,300 metres of main pipelines and 130 service pipelines were renovated.


Great benefits for both residents and municipality

The renovation work proved of great benefit to all involved. The greatest boon is that the pipelines now function faultlessly and residents no longer suffer the basement flooding that had recently become part of everyday life.


Both municipality and residents can now let go the thought of decades of problems and, moreover, feel secure in the fact of future resources being saved and available for investment elsewhere. This is because the flexible linings, according to research, have an expected lifetime of more than 100 years.


“the greatest benefit is that now all the problems can be avoided, one can feel secure that the whole area has been renovated and there is no further need to think about it for a long time to come.”

Magnus Lidberg, water and sewerage engineer, municipality of Kungälv


The final costs of proactive area renovation are lower than with unplanned reactive efforts because, among other things, fewer projects need to be undertaken. One further advantage is that the division of responsibility becomes clearer after area renovation – when the municipality has made good its share, it is easier to ask residents to maintain their own service pipes. In addition, pressure on water treatment plants is lessened; reduced infiltration means that less overflow reaches the plants and the environment avoids unnecessary damage.


The municipality of Kungälv took flow measurements in waste water pipes both before and after the pipeline renovation. The result of the comparison reveals reduced overflow to water treatment plants on account of reduced infiltration, giving the municipality clear confirmation of the benefits that the renovation has produced.

Problems with dilapidated water pipes are something that many municipalities struggle with. Large amounts of time and resources are often used on emergency measures to reduce the amount of overflow and to avoid basement flooding. Despite this, most people would probably agree that it would be profitable to carry out a comprehensive overhaul and plan efforts to solve the problem proactively. The municipality of Kungälv realised the importance of this a couple of years ago and today they are actively working to reduce overflow.