Sustainable Urban Drainage - Case Study Example

Sustainable Urban Drainage Introduction Health and hygiene is an important factor in the life of human beings. Many practices have evolved over the years in this regard and others continue to evolve depending changes in the external environment. New research has also brought forth improved means of safeguarding the health and hygiene of individuals and the society as a whole. One important factor in external hygiene is to have in place a proper drainage system that will effectively remove waste and rain water. In the past it was enough to have a system which basically utilizes the law of gravity to remove waste and water and empty it into a larger water body like a lake, pond, or sea. But as technology and urbanization has developed, it became imperative that waste management be made more responsible in terms of protecting the society as well as the environment. New waste management methods and technology was developed for this. But even then, the issue of proper eco-friendly drainage systems have continued to trouble communities worldwide. As a solution, the concept of a sustainable urban drainage system has now evolved especially in the UK. This presentation is a report to the conurbation in the UK for the implementation of a sustainable urban drainage system for that area. It will cover the advantages and problems if any of the concepts along with pointing out why it is more beneficial to the community in comparison with a traditional drainage system. The Significance of Proper Drainage System The need for a proper drainage system cannot be over emphasized, especially in urban places, where the sources of waster water are plenty. There are mainly two sources of waste water in an urban place. They are household/industrial waste and rainwater. Settlements of the past were usually on high ground so that waste and rain water would drain off naturally obeying the laws of gravity. But urbanization has made this concept impractical and the need for planned drainage systems began to emerge. As households and industries grew, the quantity and quality of the waste began to be an issue. The waste became more toxic and damaging for the health and the environment. Most drainage systems cannot handle unusually heavy rain which eventually causes temporary flooding. This rain water mixes with the waste water causing the floodwater to be unhygienic. It may permeate into the ground and mix with the groundwater. This situation is extremely difficult to rectify. In such a scenario, it is essential that the area has a proper drainage system that is efficient, will be sufficient to handle additional load, is sustainable, and does not damage the environment. Disadvantages of Traditional Drainage System The importance of a proper drainage system is in fact a result of the drawbacks of the conventional drainage system. They include polluting the land, flooding in times of unusually high discharge; can prevent recharging of groundwater, and damage to environment and wildlife. Flooding of areas where hazardous industrial materials are stored is an additional hazard. Another disadvantage is that it is very costly to build and maintain a traditional drainage system. Additions to handle increased discharge due to increased community size are difficult. Most modern drainage systems will have artificial means to handle water (like pumps and locks) which is costly to maintain in terms of manpower, and money. Many drainage systems have purification plants which are costly to maintain and operate. There are further disadvantages of traditional drainage systems that may arise if regular maintenance is not done. People have the habit of throwing rubbish and other solid waste into the drain causing it to clog frequently. Even though it is mostly under the ground, it takes up a lot of valuable space which can otherwise be used for other productive purposes like underground cabling. It needs a lot of components (apart from pumps, purification systems, and locks) like filters, adapters, and envelopes etc. More components mean more investment and maintenance costs. The Sustainable Urban Drainage System (SUDS) The word ‘sustainable’ with regard to the environment has now become a buzzword around the world today. The concept was first thought of during the Earth Summit held in Rio de Janeiro in 1992 and was formulated as a policy named Agenda 21. “Agenda 21 is a comprehensive plan of action to be taken globally, nationally and locally by organizations of the United Nations System, Governments, and Major Groups in every area in which human impacts on the environment” (Documents). The word sustainable is now added to practical all areas of development and growth. Words like sustainable development and sustainable management of forests have become common today. This concept was adopted into drainage and the concept of sustainable urban drainage came into being. It should be noted that such a system need not be implemented only in urban areas and hence that word is often omitted. The correct usage would be sustainable drainage systems. The concept of SUDS in the United States is referred to as Low Impact Development (LID). Both SUDS and LID are primarily aimed at better management of rainwater runoff so that it will not burden a city’s drainage system. Advantages of SUDS There are several advantages in using a sustainable urban drainage system in an area. In terms of cost, it is cheaper to install and implement than traditional drainage systems. As mentioned earlier, damage to the environment is minimised by lowering pollution. Surface water design is an important factor in any drainage system. SUDS offer many new and improved methods regarding this. Due to this reason, chances of flooding due to heavy rains is reduced or even eliminated. Water table can be replenished to a large extent because SUD system allows seepage of good water back into the ground. The above advantages will be clearer by explaining how the system works. Concrete and cement pavements and courtyards yards are not accepted when implementing SUDS. This will only help to collect the rainwater on the surface and let it flow into the existing drainage system. This is what causes flooding due to overload of the system. In the case of a sustainable urban drainage system, only porous materials are used for this purpose. Infiltration trenches are dug alongside roads, car parks and other public spaces so that rain water can infiltrate into the ground at the source itself. This water usually forms underground reservoirs and will seep into other water bodies. Tanks or basins lined with stones can also help to infiltrate rainwater into the ground. Catchment areas to collect such water will encourage to some extent wildlife and plant growth even in urban settings. All these steps will prevent overflow of rainwater into drainage systems which ultimately results in elimination or reduction of flooding and mixing with urban waste. Techniques used in SUDS SUDS is not confined to using a single technique or method. A single method or a combination of methods can be used according to the landscape and the type of soil in the area. New methods are also developed regularly. Some of the common methods that can be used in your area are described below. Prevention: “Prevention plays an essential part in the Management Train. This includes both the prevention of run-off and the prevention of pollution.”(Prevention). The concept behind prevention is quite simple and logical. Rainwater is not allowed to collect and drain. Instead, the methods mentioned in the previous section will allow the water to seep into the ground thereby preventing flooding and mixing with sewage. Another method for example would be to allow rainwater from the roof of a house to flow into a lawn instead of a concrete courtyard. Swales and filter strips “Filter strips and swales are vegetated surface features that drain water evenly off impermeable areas. Swales are long shallow channels whilst filter strips are gently sloping areas of ground” (Filter Strips and Swales). A diagrammatic representation of both techniques is given below. (Source: SUDS) Both these constructions will help to slow the flow of water and help for penetration into the ground. It will also help to filter any hazardous chemicals and substances that may be mixed to the rainwater. Filter drains and permeable surfaces These are quite similar in principle to the techniques mentioned above, except that they are made below the ground. Grass, paving stones and porous materials can be used to line the permeable drains. The permeable surface plays the part of trapping any impurities that may be present in the water. Infiltration Basins The principle here also is similar to the techniques mentioned earlier. “Infiltration basins temporarily store storm water runoff until it infiltrates the surrounding ground through the bottom and sides of the basin” (Infiltration Devices). These shallow depressions help to collect rain water and encourage infiltration. Usually a passage for water (for example by means of a pipe) is placed to allow water to flow into and out of the basin. (Source: SUDS) The first few inches of rain will wash off all pollutants that lie on the road or pavement and is washed into the infiltration basin. There are two types of such basins, namely on-line and off-line ones. In the case of the former, the basin gets to hold the full flow of water and when it fills the remaining water is let out through predetermined points. The disadvantage is that some of the pollutants may also be washed out along with the outflow of water. Offline basins typical allow inflow and outflow of water into it through pipes which will allow the pollutants to settle on the bed of the basin. This will prevent most of the pollutants to flow out. These can be collected at cleaned at periodic intervals. Basins and ponds: These are much larger is size and will (usually) hold water throughout the year. They are also the most important factor in the growth of wildlife in an area where they are situated. “Basins and Ponds are the main component of SUDS that can be adapted for wildlife” (Making SUDS suitable for wildlife). Lagoons and lakes can also be included under this category. Legal and statutory considerations “With respect to SUDS, this concentrates primarily on the provisions of the Town and Country Planning Act, the Local Government Act and the Water Industry Act. This legislation sets out powers for local authorities to carry out maintenance of SUDS systems and to receive payment for these activities” (Legislation Review). With regard to this area, model agreements are available which can be used as a basis when implementing SUDS in your area. This is because many stakeholders will be involved when implementing a project of this size in your conurbation. They include local government authorities, landscape developers, builders, factory and industrial establishments, and individual households. It is better to have a clear cut agreement at the start of the implementation of the plan to avoid problems in the future. Some of the problems that may be faced is given in a later section in this report. The requirements of having a SUDS as a part of the drainage system can be put as a planning obligation in the agreement. Alternatively it can be shown as a condition in the development plan. In case there are many parties or stakeholders involved it is better to have a mutually agreeable agreement with regard to implementation and maintenance of this system. Potential problems: SUDS like any drainage systems require maintenance even though not to the extent seen in traditional drainage systems. As mentioned earlier, some of the stakeholders (example builders) will be responsible of maintenance of a part of the system since it is situated within their premises. Issues as to ownership and maintenance can arise in such cases. Some of them may not cooperate unless the terms and conditions are laid out clearly and all parties involved play a part in the maintenance of the system as a whole. A clear cut agreement is necessary before the start of the implementation of the project. Another problem is maintenance of larger water bodies like ponds and lagoons. Civic authorities may not be familiar with such ecological features and may not do a good job in promoting growth to wildlife. But both these problems are not serious and can be solved through effort and foresight. Cases Successfully implemented SUD projects can be seen across a number of sites in the UK. These areas can be checked by competent authorities working with you before implementation. They include Lamb Drove - SUDS residential scheme, Hopwood Motorway Service Area, Matchborough First School, Bognor Regis Sports Centre, Wessex Water Operations Centre and Bristol Business Park (Case studies). Conclusion Most of what has been mentioned above can be incorporated into the SUD system that is to be implemented in your area. A detailed survey of the area has to be made before a final decision can be made. This is especially true in the case of larger water bodies like ponds and lagoons. In any case this project will definitely be a big step in improving the drainage system in your locality while maintaining and helping the environment and wildlife to grow. Reference Case Studies, SUDS: Sustainable Drainage System: Promoting Good Practice-a CIRIA Initiative, Viewed 24 January 2009, from Documents, UN Department of Economic and Social Affairs: Division for Sustainable Development. Un.org. Viewed 24 January 2009, from Legislation Review, Model Agreements for Sustainable Water Management System, SUDS: Sustainable Drainage System: Promoting Good Practice-a CIRIA Initiative, Viewed 24 January 2009, from< http://www.ciria.org/suds/model_agreements.htm > Making SUDS suitable for wildlife, SUDS- an Ecologist’s View, Viewed 24 January 2009, from Prevention, Sustainable Drainage System (SUDS)-Techniques, Environment Agency, Wales Viewed 24 January 2009, from SUDS, Infiltration Devices-What are they, Sustainable Drainage System: Promoting Good Practice-a CIRIA Initiative, Viewed 24 January 2009, from Infiltration Devices, Project of the Month: Infiltration Devices, Iowa Lime stone Producers’ Association, Viewed 24 January 2009, from Infiltration Devices, Filter Strips and Swales, SUDS: Sustainable Drainage System: Promoting Good Practice-a CIRIA Initiative, Viewed 24 January 2009, from Welcome to the Sustainable Drainage Website, sustainablrdrinage.co.uk, Viewed 24 January 2009, from Why Smart Drain, Smart Drain: Advanced Micro Siphon Drain Belt. Smartdrain.com. Viewed 24 January, 2009, from Read More