Denmark has approx. 2 million manholes in our sewer system and at least 200,000 of these manholes are so worn that they need renovation or replacement within the next 10 years, in order to prevent expensive and unpleasant surprises. The cost of traditional repair by excavation and replacement of a manhole in some cases amounts to DKK 100,000 - 150,000. The pipeline owner is usually a municipality whose tax payers are the ones paying the bill.

However, Per Aarsleff A/S, Pipe Technologies and Tunetanken A/S in Vejen, Denmark, now introduce a new method that reduces the costs of manhole renovation considerably. The method consists in lining a manhole with a glass-fibre reinforced liner fitting perfectly in the existing manhole, and which is strong enough to withstand external water pressure as well as the traffic load from the road above the manhole. The glass-fibre reinforced liner is inserted into the manhole in soft condition. By means of water pressure the liner is pressed against the manhole sides and shapes after the existing manhole. After this the water is heated to cure the liner, which becomes hard and abrasion-resistant. The actual outcome of the work is a new manhole with an expected life of more than 50 years. In the winter of 2001 Pipe Technologies and Tunetanken initiated joint efforts to finish and optimise the new manhole renovation method, subsequently tested on manhole renovation jobs in Kolding and Skive municipalities in Denmark.

The Tunetight method is part of a full-fledged programme for trenchless renovation methods in sewer systems comprising laterals, main pipes and manholes.