The solution is to manage stormwater through infiltration. The
basic idea is that the ambient landscape is to manage the
stormwater, so the water is either absorbed through vegetation on
roofs or on the ground, or it evaporates, infiltrates or is
collected in water basins.
"The core in our solution is a higher degree of infiltration into
the groundwater. In this way, we can lead some of the stormwater
back into the groundwater layer. And we can lead some of the water
through a low-lying area located in the outskirts of the cadastre.
Depending on the weather, a small lake will be created here. At
other times, this area will be dry," explained Jess Krarup.
Infiltration instead of discharge leads the stormwater back into
a natural circulation. Furthermore, this reduces the load on the
municipal sewer system and treatment plant. This also contributes
significantly to the maintenance and balancing of groundwater
reserves.
- Water building up in connection
with heavy rainfall
- Depth of infiltration
bed
- Infiltration through
topsoil
- Groundwater recharge
- Permeable wearing
surface
- Road bed/fascine
- Groundwater recharge
Herlev Hospital is to expand with 60,000m2 up to 2018.This
will create more paved areas which must be able to manage large
rainfall amounts in future.As part of the new Herlev Hospital, an
extensive stormwater concept is being developed in which green
surface plants will manage stormwater on the hospital's own
cadastre (Illustration: Konsortiet NHH).
The actual infiltration of stormwater is primarily through green
surface plants such as infiltration beds, trenches and verges.
Secondly, infiltration is through permeable paving such as gravel,
stony beds or asphalt that store the water in road beds/fascines
under the actual wearing surface until it sieves down into the
underlying soil, and finally into the groundwater.
Finally, there is overflow from the lowest water basins to an
existing underground detention basin from where excess rainwater is
gradually led into the municipal stormwater sewer.
With this solution, the cadastre around the new Herlev Hospital
has been dimensioned to cope with five years of rain. However, due
to the lack of opportunities to discharge stormwater to
neighbouring cadastres, the courtyards in between the hospital
buildings have been dimensioned to cope with 100 years of rain
thereby reducing the risk of flooding indoor areas.