Different than in Germany, proactive in-house rehabilitation is booming in Finland. In Scandinavia, waste water pipes in residential buildings are rehabilitated after a certain period of time has elapsed. For more than ten years, Picote Service Oy Ltd. from Porvoo has also been rehabilitating waste water pipes without chiseling and demolition work inside buildings.
The company’s more than 50 employees are mainly involved in rehabilitating the drainage systems of residential and apartment buildings and single-family and smaller apartment buildings. In 2017, a project took place in the Helsinki-Pehlajesto district, which is characterised by a large number of multi-storey residential and flat blocks built in the 1950s and 1960s in particular.
Picote works almost exclusively with the BRAWOLINER® hose liner method.
To prepare the construction site, a construction container was set up in which all the required material and technical equipment was stored. For protection, the rooms were covered with e.g. cardboard before the drainage system was decommissioned. Afterwards, access was cleared for cleaning, inspection and rehabilitation.
The cleaning of the pipes was usually done from the lower to the upper floors, so that the pipes near the bottom were not blocked by sediments that had been flushed out. Prior to rehabilitation, all pipes were analysed by means of a TV inspection.
Before the liner installation, the hose liners were prepared accordingly at Picote’s factory. The rehabilitation of the downpipes was carried out from the roof to the basement. The liners were inverted, pressurized with compressed air and then sealed with a pressure lid. As a rule, the liners were cured using ambient temperature. For this purpose, the compressed air was left in the liner overnight and the pressure was permanently measured using a specially constructed monitoring device.
After the curing phase, the junctions and inlets were opened. These were first milled open on the inlet side using a vortex cutter with the drill head and then milled flat with grinding panels.
For the rehabilitation of the horizontal connection pipes, a liner inversion with a specially developed “liner gun” takes place at Picote construction sites using the open-end method. This means that the liner ends are pre-glued with a specially designed cap, which is pulled with a holding rope after complete curing.
At the end of the rehabilitation, the drainage objects were reconnected in each case. To connect to the rehabilitated pipes, the rehabilitation service provider uses a specially developed seal that is connected to the system with epoxy resin.