Sustainable drainage systems (autosaved)(tg)

Sustainable drainage systems (autosaved)(tg)

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  Name: Thomas Geoghegan Student No: D06112565 Module: Sustainable Design Lecturer: Sonya Daly Submission: Presentation report & Presentation Project Site: Sea View Bungalow, Lurgacloy, Clogher Ballina, Co Mayo.
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  Table of Contents Page No 1. Background on Sustainable Drainage Systems (SUDS)...........................................2 2. Selecting the best SUDS option...................................................................................3 3. Above ground attenuation options..............................................................................4 3.1 Basins & Ponds...........................................................................................................4 3.1.1 What are they......................................................................................................4 3.1.2 How they work...................................................................................................4 3.1.3 Quantity.............................................................................................................. 5 3.1.4 Quality................................................................................................................ 5 3.1.5 Amenity.............................................................................................................. 5 3.2 Filters & Swales..........................................................................................................6 3.2.1 What are they......................................................................................................6 3.2.2 How they work...................................................................................................6 3.2.3 Quantity.............................................................................................................. 6 2
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  3.2.4 Quality................................................................................................................ 7 3.2.5 Amenity.............................................................................................................. 7 4. Case Study.....................................................................................................................8 4.1 Marlborough School...................................................................................................8 4.1.1 What are they......................................................................................................8 4.1.2 How it works......................................................................................................8 4.1.3 Benefits.............................................................................................................. .9 5. Why choose above ground attenuation systems?....................................................10 6. Appendix Presentation...............................................................................................11 1. Background on Sustainable Drainage Systems Drainage design in the past has been simply using a rational method size pipes to ensure water is removed as quickly as possible to ensure flooding of other areas and pollution wash off into a natural environment. A Best Management Practice is commonly used throughout the world. This is not used in the UK and Ireland, possibly because the word drainage is not included. It is referred to as Sustainable Drainage Systems (SUDS). SUDS can be quoted as offering a “total solution to 3
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  rainwater management whiletraditional drainage can be considered as only providing a “collection and disposal” Suds also apply in rural developments. Over 80% of our rivers are below ground status. Most pollution comes from: - Underperforming small treatment plants - Overloaded communal septic tanks - Clusters of single unit septic tanks - Farmyard runoff Over the past decade Irelands parks have been developing a more sustainable approach with integrated constructed wetlands. This holistic approach has been successful with dealing with farmyard runoff, industrial waste, sewage as well as urban pollution. 2. Selecting the best SUDS options When selecting SUDS it is important to consider quality, quantity and amenity equally. Too many occasions has quantity been of the highest priority. The diagram below shows the old thinking of conventional approach and is now thinking of designing for flooding to balance each element. 4
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  Figure 1.1: Diagramof conventional vs integrated There is no correct way in choosing the best suds, so several options may meet the criteria and have to be judged accordingly. Selecting and design suds are multi disciplinary processes. There influenced by factors like planning, water resource, architectural and landscape requirements. Once an assessment of the site drainage technique is done it can be selected. The selection wool is based on the surface water management train and is designed to lead the designers through selection process in: - Design techniques to meet design criteria - Drainage techniques at the top of the management train are preferred to those further downstream - There is no single correct solution and must look at external factors - The drainage system is in accordance with drainage systems Don’t approach the selection process as purely technical. Decide to put it as a wider context. For example ponds; very great environmental enhancer and increases property values a lot but overall may be overridden by other considerations. 3. Above ground attenuation options 3.1 Basins and Bonds 5
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  3.1.1 How theywork Basins are areas for storage of surface runoff are free from water under dry weather flow conditions. These include - Flood plains - Detention basins - Extended detention basins Ponds contain water in dry weather and are designed to hold more when it rains. They include: - Balancing and attenuation ponds - Flood storage reservoirs - Lagoons - Retention Ponds - Wetlands Basins and ponds tend to be found at the end of surface water management trains. They can be used to source control and can be implanted if extended treatment of runoff is required for wildlife or landscape reasons 3.1.2 How they work Basins and ponds store water at the ground surface as: - Temporary flooding - Flood plains - Permanent ponds 6
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  Figure 1.2: HowBasins and ponds work These are designed to manage under quantity and quality 3.1.3 Quantity They store floodwater and release it slowly once the risk of flooding is over 3.1.4 Quality Basins and ponds Treat run off by: - Settlement of solids in still water - Conditions and promotes settlement - Adsorption by vegetation of soil 3.1.5 Amenity The opportunities basins and ponds offer are: - Sports and recreation - Wet ponds are great to store water for reuse - Be part of public open space 7
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  3.2 Filter stripsand swales 3.2.1 What are they? Filter strips and swales are vegetated that rain water evenly off impermeable areas. Swales are long shallow channels whilst filter strips are gently sloping areas of ground. Figure 1.2: How Filter strips & swales work 3.2.2 How they work They work by mimicking natural drainage patterns by allowing rainwater through vegetation, slowing and filtering the flow. Swales are also designed for: - Infiltration - Detention 8
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  - Treatment of runoff 3.2.3 Quantity Swales are designed for: - Conveyance systems - Check dams to increase attenuations - Infiltrations Filters trips are designed for: - Attenuation Flow - Reduce drain impermeable areas 3.3.4 Quality Swales and filters remove polluting in the solids through filtration and sedimentation. 3.3.5 Amenity Swales and filters trips are often interpreted into surrounding land use Examples are: - Public open space - Road verges Grass and flowers can be planted for wildlife after the swales are in 9
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  4. Case Study 4.1Marlborough School Location: Redeltorn, Worcestershire England Description: A school development which originally was designed with conventional drainage that flowed to a pump station from where it was pumped to a school. During construction it became clear that one playground area could not be drained by gravity to the pumping station Main suds used: - Swales - Detention Basins 4.1.1 How it works The suds scheme implemented following the contour of the site and drains downhill to an ipsley stream (Removing the annual charge from the sewer construction). 10
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  Swales collect overlandflows from: - Adjacent site - Runoff from car park - Playgrounds Hence providing source of control The retention basins drain the main driveway that is connected to a constructed wetland (pond) which also takes runoff from the roof. 4.1.2 Benefits The suds system has brought a valuable amenity and teaching resource for the school 11
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  5. Why choose above ground attenuation systems? - Installed and maintained at a lower cost compared to more traditional systems of drainage - Problems can be observed and dealt with as they arise(swales) - Can be incorporated into any terrain 12
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  6. Appendix 6.1 Presentation 13