Acta Scientiarum Polonorum

Depression area in a small urban catchment without the possibility of outflow piles up surface waters from
precipitation, causing flooding. The extent of flooding depends on the intensity of rain, the size of the urban
catchment and the rainwater receiver. One of the methods of drainage is the accumulation of water in retention
reservoirs, and then transporting them into the receiver as in the case of the central part of Podborska
Street in Warsaw. This solution is not very effective because it requires continuous emptying of the retention
reservoir. Two alternative solutions have been proposed. The first one consists in the outflow of clean water
to the ground, and rainwater to a new reservoir on the other side of the street. The second one provides for
the outflow of all rainwater from the catchment to the existing rainwater drainage of the car park and the
administration building, as well as the construction of new retention reservoirs connected with a 0.5 m diameter
pipe with an existing retention system. The rainwater from reservoirs will flow through the rainwater
drainage of the car park and separator of petroleum substances with bypass to the existing storm sewer system
located in Krakowska Avenue. Existing storm sewer pipe with a diameter of 0.4 m, located under a two-lane
road is connected to the storm sewer system with a diameter of 1.0 m. In order to eliminate the flow intensity
under Krakowska Avenue, it was proposed to replace the 0.4 m diameter section with a diameter of 0.8 m in
order to allow more water to flow out in the future. The pipe replacement will be carried out using trenchless
technology, i.e. concrete pipes will be removed from the ground under the roadway by hydraulic cylinders.
On the other side of the street with simultaneous removal of existing pipes, the hole will be widened with
a horizontal non-steered drilling with a diameter of 0.9 m and, at the same time, new pipes with a diameter
of 0.8 m will be pressed.