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 Englishrainwater 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 coatings Rain garden

Rainwater tank

http://www.get2press.at/default.asp?show=showpm&pmid=3837

http://www.get2press.at/default.asp?show=showpm&pmid=3837


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:

http://en.klimatilpasning.dk/knowledge/climate/denmarksfutureclimate.aspx



http://www.globalissues.org/issue/198/human-population


“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 2010http://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 = infiltrationFordampning = evaporationKloak = sewer

The countryside A crowded city LAR city

What LAR can help in the city’s

http://www.spildevandscenter.dk/english/


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

Wat

er fl

ow

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.

http://www.laridanmark.dk/dimensionering-af-lar-anlaeg/31582



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

Prec

ipit

atio

n pr

. mm

/ 10

min

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)



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



Rain water sewages

Only delay the rain water:

• Can take lower rain volume

• The area getting more green. The down side of it:

• Need places there can take the water if needed.

Can there be use a LAR solution?

Option for Green RoofSpace for Water penetrationSpare 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.



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 down side of it:

• 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

Education

Rainwater drainage