During the next few years, construction company YIT intends to build 15 new apartment blocks in a former industrial area located about two kilometres from downtown Mikkeli. The site lies on the shore of Lake Saimaa. YIT has owned it since 1991, when the company and the City of Mikkeli made an agreement on the zoning, construction and development of the area.

It was formerly used by the wood industry – a steam-powered sawmill was established there back in 1890. In 1938–1986, a plywood mill and wooden house factory operated next to the sawmill. However, the company went bankrupt and the buildings were demolished in the 1990s.

Decades of industrial activity have left their mark on the site – for this reason, soil remediation has now been carried out. “Soil studies found substances such as petroleum hydrocarbons and heavy metals. During the remediation work, thousands of cubic metres of contaminated soil were removed and replaced with clean new soil,” says Petri Pynnönen, Supervisor at Talpa Oy, which is currently carrying out a contract to install a new water main that will serve around 2,000 residents.

Slightly less than 200 metres of the kilometre-long pipe runs through the remediated area. Even though the soil is now clean, the developer, the Mikkeli Water Utility, wanted to be absolutely sure that the water main would be safe. Uponor Barrier PLUS pipes with a diameter of 225mm will be used for the section of the water main that passes through the previously contaminated area. The rest of the main will be built using ordinary Uponor PE water pipes.

Pynnönen says that the first apartment buildings were erected on this peninsula in the 1990s. “The plastic pipes available back then did not provide protection against pollutants, so the water lines were made using cast iron pipes.”

Easy to handle, quick to install

 Talpa wanted to use plastic pipes for the project – and, after hearing about the new Uponor Barrier PLUS pipes, decided to choose them. “This is our first project in which we’re using Barrier PLUS pipes,” says Pynnönen.

They proved to be very easy to handle and install. “The pipes are light and flexible, thanks to which they are easy and fast to install. Their flexibility also means that small changes in direction can be implemented safely.” 
He also praises the speed and ease of installing wraps around the pipe seams. There are just under 20 seams on the 200-metre section of pipe. “The work is going very smoothly – it only takes about 10 minutes to wrap each seam. Once the plastic wrap has been installed around the protective jacket of the pipe, a shrink sleeve is heated over it to seal it tight. The wraps and shrinks are pre-dimensioned for the pipe, so there is no need to measure or cut them to fit.