Rain gardens at Przy Bernardyńskiej residential project in Warsaw
The high requirements for the design of green areas specified in the building permit became a challenge to create a space, which, apart from good architecture, was a strong point of the investment. We had the opportunity to arrange a space that was exceptionally rich in form, and thus very coherent – the shore of the lake in the form of a promenade with numerous elements of small architecture connected with a system of footbridges and bridges with the other, more natural shore.
Particularly noteworthy here is the created artificial swamp ecosystem, which acts as a rainwater receiver – a purification device and at the same time a regulator of the hydrological system. The project fits into the urban landscape as a new type of green area. Thanks to this, the unique effect of an enclave embedded like the Vistula forests in the middle of a bustling city was achieved.
The decision on the building permit obligated the investor:
- to manage the entirety of rainwater and snowmelt in the area of the investment
- rainfall and meltwater from roofs and hardened areas should be drained through the retention and infiltration tank to the ground
- rainfall and meltwater from inlets and linear drainage of balconies, terraces, and logs, as well as garage ceilings and pavements should be drained to green areas
- the emergency projection of the water is to be outside the plot to the sewer
- the amount of water discharged could not exceed 2.51 / s and the discharge of water should be suspended during high water levels in the canal
The investment is located close to the Jeziorko Czerniakowskie nature reserve and the canal on the border of the property. The facility was designed with the residents of the estate in mind as an area of recreation and relaxation, the most important devices used in the project were:
- a large pond with a filtration zone of the area of 3,500 sq m, the task of which is to maintain good water quality in the reservoir,
- roof air filter 5,500 sq m as supply to the main reservoir, infiltration zone with a floating canal of the area 1,500 sq m. Rainwater filtration in overgrown infiltration basins is the best and cheapest way to purify water. Due to its efficiency, it is used, for example, in groundwater intakes, where disconnecting drainages or absorptive wells are not allowed.
- 3 cascades with a total area of over 6oo square meters, which perform the functions of water aeration and decorative functions, for the system to function properly, it is additionally equipped with several devices, such as a pump system located in 3 pumping station chambers, plus 5 filtration chambers located under a 20-meter promenade.
The system operates as follows:
- Roof filters collect rainwater, clean it and discharge it directly into the tank.
- Water from the road surface through the separator goes to the floating channel from where it goes to the infiltration zone.
- The water circulation in the tank is designed to lead the water through the biological bed (filtration zone), for this purpose it takes water using skimmers (surface collectors), by pumps, it is pumped to the filtration marsh zone, where it is treated using filters composed of layers deposits and plants, and then filtered tafia to the main reservoir.
- Water for cascades is also drawn from the reservoir.
- Aerated water from the cascades returns to the reservoir.
- The excess water from the reservoir is discharged through bottom outlets to a collecting sump, from which it will then flow out into an unsealed infiltration basin and then into the ground at a regulated outflow.