It only takes a few seconds for 1 liter of water to sieve into
the subsurface on Helenevej in Frederiksberg.
"It's almost like a sponge or a sieve. The water simply sieves
down into the street," explained Susanne Viuf, head of division
from the City of Frederiksberg, which is home to the first climate
street in Denmark.
The new surface on Helenevej was designed specifically to manage
great volumes of water and to keep basements in the area dry during
cloudbursts in Copenhagen.
Preparing the street for cloudbursts has cost DKK 920,000, but the
sewers at Helenevej had to be renovated anyway, and this drainage
solution turned out to be cheaper," said Susanne Viuf.
"We've avoided having to lay completely new sewer pipes, so we've
actually saved DKK 500,000 compared to a traditional solution.
Moreover, the street can hold extremely large volumes of water
compared to what a sewer pipe can hold," said Ms Viuf.
Helenevej is now able to absorb 75m3 stormwater during a
cloudburst or the equivalent of 100 years of rainfall.
The street itself is built on a stable layer of particularly
drainage-friendly gravel, and the surface is made of small square
tiles. The tiles are clicked together thereby ensuring stability.
The joints are filled with fine pebbles or crushed stones which
allow the water to sieve quickly into the ground. Below the street
are four locks that collect the stormwater which is slowly led down
into the subsurface.