Rainwater drainage

Rainwater drainage/Lokal afledning af regnvand (LAR) By Morten Hoegsdorf Student on KEA as Architectural Technology
What challenges have Denmark's
sewers in the future?
• Can it be a challenge that the city's
getting bigger?
• Can sewer take it in the future?
• Do we get more rain?
• Do we need to change the way we
directs water away from the surface?
• What about Co2?
Local drainage of rainwater in short LAR on Danish

So there need to be look on:
• Redirecting rain water or build bigger
sewers?
• Can the rain water be delay and how
(LAR solutions)?
• Is there a way for combine solutions
and lower the Co2 in same project?
• Is there one way, or do we need to
combine different solutions?
What can we do?

Drawn by ”Lulu Jacobsen, Haveselskabet”
http://www.get2press.at/default.asp?show=showpm&pmid=3837
“Lokalt afledning af regnvand”
(Danish) on translated to English
rainwater drainage.
• Dealing with local rain water by.
• Slowing it down before going
to the sewers.
• Leaching into groundwater
• Stored in container or direct
it to places with capacity to
withstand the rain.
• Minimize flooding There are variety of methods to
do help reduce the risk of water
damage in residential such as:
What is LAR
Green roof
Water penetration coatingsRain garden
Rainwater
tank

LAR
Experience
Environment
Drainage/sewers
(surrounding area)
Climate change Statutory
Dimensioning of
LAR-systems
Possible actions
By combining the knowledge of:
• Drainage/sewers
• Climate change
• Environment
• Statutory
• Experience in ”LAR”
It likelihood you have/get a good
foundation to make actions on.
From problem to solution

Note:
DMI har nedskaleret de fire scenarier, så de passer til
danske forhold (A1B, A2, B,2 og EU2C)
“Climate change in Denmark calculated with the Danish Meteorological Institute's
regional climate model HIRHAM5 on the basis of projections carried out with the
global climate model ECHAM5 in connection with the EU project ENSEMBLES. All
figures in the table show changes for the period 2021/2050 relative to the normal
period 1961/1990”
“.klimatilpasning”
http://en.klimatilpasning.dk/knowledge/climate/denmarksfutureclimate.aspx
Around the globe, people are talking
about climate change, but how will this
effect the world and Denmark in the
future and how?
“In the long term, the magnitude of
changes in climate will depend on how
much greenhouse gas is emitted globally
in the decades to come” (Klimatilpasning)
But are we sure that it only greenhouse
gas there effect the climate?
What about “over population” there
contribute to the
waste, consumption, deforestation and
bigger city's?
Global Issues:
http://www.globalissues.org/issue/198/human-population
Future climate in Denmark:

“The table shows selected extreme weather indicators for the four climate scenarios.
The figures show the differences between the periods 2071-2100 and 1961-1990. As
described above, the figures for the A1B scenario have been calculated with another
model system than the figures for the other scenarios. The last column shows the
models' present value as the average between the two present-value simulations in
the study. The present-value results are not completely identical with the measured
values for the period 1961-1990, but are fairly consistent with these.”
Many claim that we get more extreme
weather in Denmark, but how accurate
is it and can we believe it?
“The uncertainty of the temperature
calculations is 1.5ºC for the A2 and B2
scenarios, and 0.7ºC for the EU2ºC
scenario. This means that there is a 90%
probability that temperature increases in
the three scenarios will be between 0.7ºC
and 4.6ºC in the period 2071-2100.”
(Klimatilpasning)
More extreme weather in Denmark:

Statistics statement claim that we:
• Going to be more people on
earth, due to better life
conditions, this contribute to
bigger city’s, and therefore less
area, in that particular city to
consume the rain water, duo to
more sewage in the sewer.
There are a possibility for:
• More extreme weather if we
follow that same path.
So what can “LAR” help With?
Facts and possible in the future city’s.

Illustrations on his slide by Lærke Kit
Nielsen, Orbicon
LAR metodeguide 2010
http://www.spildevandscenter.dk/english/
LAR solutions can:
• Be flexible so they can fit where there is a need.
• Often be significantly less expensive compare to
expand the sewers.
• Create new small green areas and brings water into
the city.
• Improve the city's microclimate and provides more
space for experiences and nature.
Nedsivning = infiltration
Fordampning = evaporation
Kloak = sewer
The countryside A crowded city LAR city
What LAR can help in the city’s

If the water flow are bigger in the
sewers can take “capacity”, can be due
to urbanization (physical growth).
What can there be done?
• Necessary to extend the sewers
New sewers in the area
• Incorporate a LAR facilities there
can slow down the water so that the
sewers capacity can take it
Illustrations on his slide by Thomas Aabling, Søren
Gabriel og Karsten Arnbjerg-Nielsen
http://www.laridanmark.dk/dimensionering-af-lar-
anlaeg/31582
New sewer capacity
Time
Sewers capacity
Waterflow
Necessary
LAR
capacity
Sewer vs LAR
“It requires sophisticated models to find exactly
this volume, better make it bigger then it is
require”
Method guide 2010 Spildevandscenter Avedoere.

LAR systems and sewage works
completely differently
The sewers:
• Can take up to a certain point before a
flood.
The LAR system:
• Can slow down the water for a time
period.
• Can direct it away for storage to
evaporate, or into the sewers
• But there is are a risk for a flood, if the
volume of the rain are more intense
what it can transport away.
Illustrations on his slide by Thomas Aabling, Søren
Gabriel og Karsten Arnbjerg-Nielsen
http://www.laridanmark.dk/dimensionering-af-lar-
anlaeg/31582
Time
Precipitationpr.mm/10min
Sewer vs LAR

Existing sewage outline from:
HTK Forsyning A/S Lervangen 35D 2630 Taastrup.
Sewages from the
residential
Rain water sewages
New residential area sandbox seniors in Denmark (DK)

Sewages from the
residential
Rain water sewages
Detention pond
Detention pond:
• Option for the rain water to be
stored.
The down side of it:
• Pushing the problem to a other
place.
• Can it withstand all the water
and do it have to be filtered?
The surrounding area

Sewages from the
residential
Rain water sewages
Only delay the rain water:
• Can take lower rain volume
• The area getting more green.
• Need places there can take the
water if needed.
Can there be use a LAR solution?
Option for Green Roof
Space for Water penetration
Spare for faskine
Road Road
Road Road

Source : LAR metodeguide 2010 and Lærke Kit Nielsen from Orbicon.dk
Spildevandscenter Avedoere, Copenhagen
” The assessment is based on the deployment over existing land use so
as to reduce leakage, the grass is assumed to be on existing lawns, and
thus get 0 in space requirements. The methods that are expensive to
build gets 3, and the methods that can.”
Choices are based on experience
Methods guides is
available
online, where
organizations and
companies together
developed their
experience, over
time.

Sewages from the
residential
Rain water sewages
The best way to handle rain water is
by:
• Combined different methods like.
• Green roof, rain garden, water
penetration coatings, ditches,
fascine, lake, wetland
• The lack of space.
• There need more focus on it.
Combination of delay and storage.
Green Roof Detention pound
Water penetration
Faskine
Road Road
Road Road

My conclusion and experience
Summary:
• We are not 100 percent that are going to be more volume rain in future. But we are getting
bigger city’s
• = More water in sewers, less green area if we don’t act.
• LAR facilities can provide green area and taking care of rain water but:
• There is a risk for a flood, if we do not take extreme weather to account and make sure
that water can get away.
• Combining space, connection to sewer and money available in the area in a early stage of
construction.
• A better result in the end.
• Some claims that trees and greenery reduces Co2, but I’m not 100 present confident about it
but.
• Green area attracts wildlife, microclimate and people like oasis.

Thanks for listen have a nice day

Rainwater drainage

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