Beneath Tallinn lie 50 kilometres of pipes tall enough to walk through upright

Marti Vaksmann, head of pipeline planning and construction at Tallinna Vesi, the Estonian capital's water utility, has revealed that roughly 3,000 kilometres of pipelines of various sizes run beneath Tallinn. About 50 kilometres of that network consists of pipes large enough for a person to walk through while standing at full height.

He made the comments in connection with construction work that has been under way all summer at a crossing near the city's hippodrome, where most of the repair activity is happening underground. According to Vaksmann, excavation at this particular site reaches a depth of about four metres, though in some parts of Tallinn pipelines lie as deep as 30 metres below the surface.

Old system being replaced

The existing pipes were laid almost a century ago, when Tallinn relied on a combined sewer system in which rainwater and wastewater flowed through the same pipes. At the hippodrome crossing, crews are now installing a separate pipeline dedicated to rainwater, since planners expect rainfall to become more intense over the next 50 years and want to avoid rebuilding the system again in the future.

Vaksmann noted that although the crossing may appear to passers-by as if little construction is happening, most of the work is in fact taking place below ground. He also said he personally enjoys working with pipes and does not feel fear inside tight underground spaces, though he acknowledged that many people find such confined conditions unpleasant and that someone still has to do the job.

Beyond the large pipelines, the same area also contains water supply and sewage pipes, district heating lines, and various cables running beneath the pavements. Engineers generally try to place pipelines as close to the pavement as possible, and there are no buildings directly above the section where the pipes run.