Goodbye to 100 manholes

In 2001, Aarsleff Pipe Technologies started working with the local authorities of Skive on inspection of 284 access manholes. One of the most significant reasons for commencing the project was that the local authorities wanted to minimise operation and maintenance costs.

Many of the 284 manholes were old and worn out. In addition, many of these had been established so long ago that they were placed at intervals of 40-50 metres. Today, we typically place new manholes at intervals of 100-150 metres. The reason for this is that we have now developed highly efficient methods for cleaning and inspection of sewer mains including sophisticated CCTV inspection equipment. Previously, manhole inspection was carried out by flashing a torch into the manhole, or perhaps by crawling down into the manhole to inspect it manually. Naturally, this resulted in highly inaccurate measuring and assessment results of the condition of manholes and pipe systems.

Once we had implemented the large-scale inspection work, we carefully reviewed the results together with the local authorities’ employees. We decided to seal up some 100 manholes. For the local authorities of Skive, this meant considerable future cost savings in terms of operation and maintenance. For instance, it meant 100 fewer manhole rings that would otherwise have obstructed snow removal in the winter season and thus be damaged.

The work of inspecting and sealing up the high number of manholes took place during a period of approx. six months. The project also included preparation of documentation stating the condition of the manhole both before and after sealing. We sealed the manholes by installing a short Aarsleff CIPP Lining in the main pipe, and subsequently we filled the manholes with sand.