PERMEABLE PAVING SOLUTIONS

Transcription

1 BRETT LANDSCAPING Commercial Support CI/SfB April 2010 (90.4) Ff2 PERMEABLE PAVING SOLUTIONS USING CONCRETE BLOCK PAVING

2 BRETT LANDSCAPING Commercial Support WHY SUSTAINABLE DRAINAGE? Sustainability is today a major factor within the construction industry, influenced by both planning guidance and legislation. In most cases, we can see that the key drivers behind this change are the conservation and management of two of our most precious commodities energy and water. It is for this reason that Sustainable Drainage Systems (SUDS) are becoming an essential component of our built environment, as they add value to all three areas of sustainability. The effective integration of SUDS into master planning, for both urban as well as residential developments, will enable us to better manage our water resources. As a long established manufacturer and supplier to the built environment, Brett recognises its responsibility to develop, promote and support products, including permeable paving, for use within SUDS design. These products must be capable of seamless integration into all forms of the hard landscaped environment to enhance water quality, minimise flood risk and improve the management of our most valuable natural resource - water. The effective use of SUDS can help to mitigate the impact of the more extreme weather events that we are seeing as a result of changing climate patterns and of our ever increasing demands on land usage. Today virtually all developments and products are assessed to see how they can add environmental, social and economic benefits to the built environment. Environmental quality We need to maintain or improve our water to preserve the natural environment We need to reduce SUDS Deliver benefits in all three areas of development We need to use our natural that does not compromise future availability which can have catastrophic economic effects the Economic frequency of major flooding events Social resources in a way Sixfields, the largest permeable paving project in the UK, uses Brett Omega Flow. 2

3 Contents Flood and pollution risk 4-5 Legislation and guidance 6-7 Permeable paving as a solution 8-9 Permeable paving and management train Brett Permeable paving ranges OMEGA FLOW 12 ALPHA FLOW 13 About Brett 14 Case study 15 3

4 T234 BRETT LANDSCAPING Commercial Support FLOOD AND POLLUTION RISK Growing urbanisation has resulted in the increase of impermeable areas - roads, driveways, parking facilities, pedestrianisation and roof surfaces. This, coupled with higher density patterns of construction, has led to ever-larger areas with very rapid water run off and a proportionately reduced area where natural, permeable drainage can occur in a controlled manner. This means that rainfall moves very quickly from impermeable hard surfaces through to watercourse with little reduction in either volume or speed. In turn, this means that there exists a progressively higher risk of flooding. Permeable paving has the ability to attenuate the speed and volume of run off, thereby minimising local flood risks and collectively, mitigating flood risk over larger areas. THE URBANISATION: RUN OFF EQUATION The speed of water run off can vary by up to 90% from an undeveloped rural area through to a heavily urbanised area, as we can see from the illustrations below. Given increasing urbanisation, the new agricultural techniques and rapid expansion of cities and transport infrastructure that we have seen over the past century, the risks from faster run off and more pollution are obvious. 5% 95% 30% 70% Rural undeveloped Agricultural 95% 5% 70% 30% High density urban Suburban 4

5 POLLUTION Another direct result of the increase in urbanisation is the environmental pollution from hydrocarbons and heavy metals resulting from vehicle usage and power generation. These come on top of the other water contaminants like dust and faeces that occur within an urban environment. Fast and uncontrolled surface water run off carries this pollution with it almost undiluted, directly into our water courses, where it can be harmful to our wildlife. CHANGING WEATHER PATTERNS Climate change is an inevitable factor for us all: in the UK the effects have been seen in warmer, wetter, weather with more frequent extreme rainfall events. This storm water drains rapidly from the typical urban environment, causing an early peak in flow rates that can overwhelm older sewers, many of which date back to the Victorian era, and trigger a widespread flooding event. This can be contrasted with how SUDS replicate the natural flow of water with a higher base flow, as water is retained in the system, leading to a reduced and delayed peak flow rate. This serves to greatly reduce the risk of a major flood event as well as offsetting the effects of climate change and urbanisation. Pre and post-suds development run off hydrographs following storm rainfall over an urban area. Traditional drainage systems pre-development Storm Event Higher and more rapid peak discharge With SUDS systems post development Steeper recession Flow (m³/s) More run off volume Lower and less rapid peak Gradual recession Higher base flow Time 5

6 BRETT LANDSCAPING Commercial Support LEGISLATION, GUIDANCE AND HOW SUDS PROVIDES SOLUTIONS The pressure to develop is unrelenting. An ever increasing demand for new housing is resulting in the use of more greenfield sites and the loss of their natural drainage patterns. The need to minimise the impact of these changes has been recognised in the Code for Sustainable Homes, where surface water management is one of only four mandatory elements with the objective being to provide drainage that is as effective as the natural landscape was before the development. At the same time, the demand to utilise more brownfield land requires more stringent pollution control to prevent pollutant leaching and to maintain water quality. It is for this reason that flood risk, run off and pollution are now amongst the most heavily legislated and monitored areas of planning and construction. Given that surface water management is a relatively new area of construction, it is fair to say that the way in which the planning, guidance and legislation fit together to form a logical hierarchy, is complex. PREVAILING POLICY AND LEGISLATION Pollution Flood All-encompassing European Water Framework Directive (WFD) 2000 Requires that surface water discharges are managed so as to mitigate their impact on the environment. Incorporated into UK legislation in The Pitt Review 2007 Independent review and recommendations after the 2007 floods. Future Water for England 2008 This strategy sets out the Government s long-term vision for water and the framework for water management in England The Flood and Water Management Act 2010 The Act responds to recent pressure to introduce legislation and addresses the threat of flooding and water scarcity. It draws together the previous recommendations of the Pitt Review and the strategy of Future Water for England thereby giving effect to the WFD in the UK and providing a cohesive approach to water management. Authorities are now required to develop flood risk management strategies and sustainable drainage systems in certain new developments. This will help to manage and reduce the flow of surface water into the sewerage system as well to improve water quality. 6

7 SUSTAINABLE DRAINAGE AS A SOLUTION SUDS offers a hierarchy of techniques for surface water management designed to replicate the natural drainage pattern. The objective is to reduce the impact of urbanisation on watercourses and also to deal with surface water run off as near to the source as practicable by infiltration and attenuation. This is termed source control. As well as the preventative measures that SUDS can offer to reduce the volumes of water entering the water course, its source control principles can also intercept pollution by the introduction of filtration and containment at, or near, the point of contamination. THE BEST OUTCOMES The three-fold objective of SUDS is to provide drainage techniques for urban developments which: 1. Attenuate the flow rate of water run off. 2. Minimise the levels of pollution passing into the watercourses at run off, therefore preserving the aquatic environment. 3. Enhance amenity, by preserving the environment and wildlife habitats. Control and minimise water quantity SUDS Enhance amenity and wildlife Improve water quality Brett offer a range of permeable pavement solutions - a proven source control technique in handling surface water run off.and controlling pollution. Our technical experts have been associated with the development of national standards and have a wealth of experience in the practical application of permeable paving as SUDS solutions. A T E R IA L M R IB A C P D A S S E S S E D We also offer training to your personnel in the specifier, Local Authority or contractor sectors through our RIBA approved CPD seminars. To arrange a CPD seminar, please contact Brett on The environmental benefits of SUDS 7

8 BRETT LANDSCAPING Commercial Support PERMEABLE PAVING SYSTEMS BENEFITS Run off control Conventional pavements, car parks and hardstanding areas are designed to simply shed water from their surface, whereas permeable pavements allow the water to pass between each block and into the underlying sub-base. Here it can be stored, channelled or slowly released in one of three ways - into the ground, passed on to a further stage of SUDS management or passed into the drainage system. But it is the attenuation of water that is important, enabling permeable paving systems to reduce first flush, control peak rates and total volume and frequency of run off by employing the principle of source control. Permeable paving can also be used to handle run off from surrounding impermeable areas such as roofs and surrounding impermeable areas so long as a factor of approximately 2:1 is maintained, thereby maximising the hydraulic capability of the permeable paving. Pollution control The second major benefit of permeable pavements is their ability to reduce pollutants, at or close to the source. Pollutants can be retained on the surface of the pavements (especially where there is little or no fall), before being carried through to the laying course and sub-base layers during a rainfall event, where they can be trapped and degraded over time. CIRIA*, the leading body in the research for SUDS, states that 60-95% of suspended solids and 70-90% of hydrocarbons can be removed by permeable pavements in this way. This means that not only do they not require oil separators, but are also more efficient at removing a wider range of pollutants than conventional oil separators would be. *Construction Industry Research and Information Association Space efficiency Permeable pavements are a very space-efficient solution and ideal for high density housing and construction projects. The removal of the need for oil separators and attenuation tanks results in greater space efficiency and cost savings. The ability to install pavements without the associated underground pipework used in conventional drainage systems, provides additional cost benefits to projects. Permeable paving run off and pollution control Pollutants trapped in laying course and/or geotextile Pollution combines with rainwater and infiltrates Rainfall Rainwater infiltrates Permeable paving Laying course Hydrocarbons bio-degraded in sub-base Geotextile (optional) Geotextile Sub-grade Sub-base 8

9 PERMEABLE PAVING DESIGN Permeable pavements must be designed to deliver two objectives: 1. Supporting the planned traffic loading 2. Managing surface water effectively Two sets of calculations are therefore required when designing permeable pavements. Structural design Assessment of traffic loading pre and post-construction Assessment of sub-grade California Bearing Ratio (CBR) value Determination of sub-base thickness A temporary dense bitumen macadam (DBM) layer can be used during site construction to prevent damage to the sub-base. Prior to commencing construction of the block layer, the DBM should be cored or punched with 75mm holes on a 750mm orthogonal grid. However, this method may reduce the storage capacity of the pavement and require a deeper sub-base to compensate. Hydraulic design Assessment of sub-grade permeability Selection of System A, B or C dependent upon sub-grade permeability, existing or ground pollution (especially on brownfield site developments), water table levels and proximity to Source Protection Zones Determine design return period and rainfall data. The return period is an event occurring on average once over a defined period, typically this is 1 year in 30, 1 year in 100 or 1 year in 100 plus 20% Allow for additional drainage for adjacent areas which can include drainage from roofs. As a guide, a ratio of impermeable to permeable paving should be approximately 2:1 Determine sub-base thickness required for water storage. This may need to be deeper depending upon the slope of the pavement as a steeper slope will reduce the storage capacity of the sub-base Determine discharge rates. Select the greater sub-base depth The Brett Commercial Support team can assist with all aspects of this process. Contact Permeable paving Permeable paving Laying course Geotextile (optional) Laying course Geotextile (optional) Permeable sub-base Permeable sub-base Sub-grade Geotextile Sub-grade Impermeable flexible membrane Sub-grade System A: total infiltration All water falling onto the pavement infiltrates down through the joints between the concrete blocks, passing through the constructed layers below and eventually into the sub-grade. The sub-base layer may act as a temporary storage device. System B: partial infiltration Similar to System A, but with a series of perforated pipes or fin drains at the formation level at the bottom of the sub-base, to allow the remaining water to be drained to other systems such as sewers, swales and ponds or watercourses. System C: no infiltration Allows for the complete capture or attenuation of the water using an impermeable membrane placed on top of the formation level. Pipes or fin drains restrict the outflow of water from the pavement. 9

10 BRETT LANDSCAPING Commercial Support USING PERMEABLE PAVING IN SUDS MANAGEMENT TRAIN SCHEMES Management train or treatment train are terms used for an integrated sequence of measures employed in a SUDS scheme which, taken together, control volumes of run off and reduce pollution before discharge. These measures are designed to emulate the natural catchment process. The critical function of any SUDS system is to control surface water run off as near to its point of origin, that is where the rain falls and/or accumulates, as possible. Termed source control, this can mitigate the speed of run off, direct and guide it before finally controlling its passage off or through the surface. Permeable paving, when used as part of a SUDS management train design, is used to control run off by infiltration and attenuation, whilst at the same time, introducing various levels of pollution control. Conventional tiled roof Green roof Run off Impermeable paving Swale Soil Permeable paving Source control The illustration above shows how permeable pavements can be integrated into a SUDS management train. With its spare hydraulic capacity, permeable pavements are ideal as a source control for run off from roofs as well as adjacent impermeable pavements or other impermeable hardstanding areas. Site control 10

11 THE FOUR PRINCIPAL STAGES OF A SUDS MANAGEMENT TRAIN Run off to grass Evapotranspiration Storage 1. Prevention good site design and effective housekeeping measures can help minimise run off and pollution levels. These approaches should generally be included within the site management plan to ensure that they are implemented. Infiltration Conveyance 2. Source control effective control of run off at or very near its source, this can be achieved with features such as green roofs, soakaways, rain gardens and permeable pavements. When rainwater is harvested on site it can be re-used as a source of non-potable grey water thereby reducing the demand for fresh mains water. Evapotranspiration Conveyance 3. Site control planned management of water in a local area or site examples would include routing water from building roofs and car parks to soakaway or infiltration areas and then to storm tanks or a detention basin thereby attenuating the flow of water entering the system after a storm event. 4. Regional control designing a system that can efficiently manage the run off from a site, or several sites, typically resulting in a balancing pond or wetland. This provides a natural method of handling excess water thereby reducing the risk of flooding events. Balancing pond Discharge to storm or main drainage Regional control 11

12 BRETT LANDSCAPING AND BUILDING PRODUCTS Commercial Support PRODUCTS OMEGA FLOW Brett Omega Flow is a classic rectangular block profile and purpose designed nibs to enhance permeability. This contemporary, clean style will complement most environments and has been designed for use in either hand or machine lay applications. In addition to Omega Flow, we also offer a wide range of complementary products, including kerbs, which can further enhance any project using Omega Flow permeable block paving. Where planned for use in machine lay applications, Omega Flow comes pre-palletised in clusters of 48 or 64 blocks for use in standard 45 herringbone block paving patterns. MACHINE LAY B R E T T Brindle (BR) MACHINE LAY B R E T T MACHINE LAY B R E T T Charcoal (CL) MACHINE LAY B R E T T Application and Installation Brett Omega Flow is suitable for a wide range of paving applications. For further details please refer to BS 7533 Part 3: 2005 and Part 13: PLEASE NOTE: This product is specifically designed to be hand or machine laid in permeable pavement applications with permeable sub-base materials & techniques. Colour As shown. Other colour requirements will be considered on request. Texture Smooth surface with a 6 x 4mm chamfered edge. Manufacture and testing Brett Interlocking Concrete Blocks are manufactured and tested in accordance with BS EN 1338: All Brett production facilities operate to a BS EN ISO 9001: 2008 registered quality management system. Permeability rates Brett Omega Flow has been independently assessed to have a water permeability rate of 4,265 mm/h when laid in accordance with our recommendations.this compares with a typical UK rainfall intensity of 75mm/h. Autumn Gold (AG) Burnt Oak (BO) Strength Characteristic tensile splitting strength not less than 3.6Mpa when tested in accordance with BS EN 1338: Abrasion resistance The abrasion resistance is designated as Class 3, when tested in accordance with BS EN 1338: Durability Brett Concrete Paving Blocks are resistant to weathering, including freeze-thaw and to the varying traffic requirements described and specified in BS 7533: 2001 Part 1 and 2. Packaging The blocks come void packed as standard to reduce site wastage, however when required for machine lay applications they come palletised for ease of use. Omega Flow standard blocks specification table Block Thickness Code Plan size Blocks Area (m 2 ) Blocks Cluster size Pack weight (mm) ± 3mm (mm) ± 2mm per m 2 per pack per pack (mm) (kg) Standard 60 OF X n/a 970 Standard 80 OF X n/a 1030 Omega Flow machine lay clusters specification table Block Thickness Code Plan size Blocks Area (m 2 ) Blocks Cluster size Pack weight (mm) ± 3mm (mm) ± 2mm per m 2 per pack per pack (mm) (kg) 48 cluster 80 OF80ML 215 x x cluster 80 OF80ML x x Notes This product is specifically designed for use in permeable pavement applications and with permeable sub-base materials and techniques. In the manufacture of concrete products, colour consistency cannot be guaranteed and variations in shade may occur. Care has been taken in the calculation of the estimating factors contained in this document, however, when they are used to prepare quantities, Brett Landscaping cannot be held responsible for any shortfall or excess of materials that may occur during the installation on site. Add BR/CL/AG/BO to specify colour. For example, the code for an Omega Flow 80mm thick, large block in Charcoal would be OF80CL for hand lay product or OF80MLCL for where machine lay product is required in a 48 block cluster. 12

13 ALPHA FLOW Small Medium Large Brett Alpha Flow is a classic, cobble-style, block paver with three block sizes which all have tumbled edges and interlocking spacer nibs designed to enhance permeability. The three unique Alpha Flow block sizes allow for the creation of a wide range of differing random patterns that will all interlock. Brett can supply a range of the most popular of these patterns to make it easy to install on site. Brindle (BR) Charcoal (CL) Application and Installation Brett Alpha Flow is suitable for a wide range of paving applications. For further details please refer to BS 7533 Part 3: 2005 and Part 13: PLEASE NOTE: This product is specifically designed to be laid in permeable pavement applications with permeable sub-base materials and techniques. Colour As shown. Other colour requirements will be considered on request. Texture A rustic, cobble-type paving block with a surface tumbled edge detail. Manufacture and testing Brett Interlocking Concrete Blocks are manufactured and tested in accordance with BS EN 1338: All Brett production facilities operate to a BS EN ISO 9001: 2008 registered quality management system. Permeability rates Brett Alpha Flow has been independently assessed to have a water permeability rate of 3,386 mm/h when laid in accordance with our recommendations.this compares with a typical UK rainfall intensity of 75mm/h. Autumn Gold (AG) Strength Characteristic tensile splitting strength not less than 3.6Mpa when tested in accordance with BS EN 1338: Abrasion resistance The abrasion resistance is designated as Class 3, when tested in accordance with BS EN 1338: Durability Brett Concrete Paving Blocks are resistant to weathering, including freeze-thaw and to the varying traffic requirements described and specified in BS 7533: 2001 Part 1 and 2. Packaging The blocks come void packed as standard to reduce site wastage. Alpha Flow specification table Block Thickness Code Plan size Blocks Area (m 2 ) Blocks Cluster size Pack weight (mm) ± 3mm (mm) ± 2mm per m 2 per pack per pack (mm) (kg) Small 60 NLAFS x n/a 1250 Medium 60 NLAFM x n/a 1250 Large 60 NLAFL x n/a 1250 Small 80 NLAFS x n/a 1215 Medium 80 NLAFM x n/a 1215 Large 80 NLAFL x n/a 1215 Notes This product is specifically designed for use in permeable pavement applications and with permeable sub-base materials and techniques. In the manufacture of concrete products, colour consistency cannot be guaranteed and variations in shade may occur. Care has been taken in the calculation of the estimating factors contained in this document, however, when they are used to prepare quantities, Brett Landscaping cannot be held responsible for any shortfall or excess of materials that may occur during the installation on site. Add BR/CL/AG to specify colour. For example, the code for an Alpha Flow 80mm thick, large block in Charcoal would be NLAFM80CL 13

14 BRETT LANDSCAPING Commercial Support ABOUT BRETT We work closely with architects and specifiers from both the private and public sector to create working partnerships that succeed through every level of design, application, installation and final use. PRODUCT Brett Landscaping is the second largest manufacturer of block paving in the UK and our Cliffe site is today the largest manufacturing site of concrete block paving in the UK. We have in our portfolio many renowned and long-proven brands such as Trief and Kassel specialist kerbs - in fact Brett is now one of the leading safety kerb manufacturers in Europe. These well established and highly effective products are complemented by an innovative and comprehensive design service and technical support. Through our expertise, gained over many years, we are able to offer extensive support through to the design and installation of our products. SERVICE Few areas of construction have as much published guidance and legislation covering them as the future of our urban landscapes. As a leader in hard landscaping solutions, we believe that it is our responsibility to provide advice to our clients, guiding them through the relevant legislation in order to achieve the optimum hard landscaped environment. This can range from master planning and meeting pre-tender conditions through to complying with statutory requirements and provision of integrated system solutions. Brett continually demonstrates that good advice, good design and good products go together to provide the very best hard landscaping solution. Integrated design, specification, ordering and delivery packages can be provided for projects of all sizes - furthermore, our advice continues to be available on maintenance, refurbishment and cleaning, long after the project finishes. OPERATIONS When it comes to our operations, we go beyond the standard levels of monitoring environmental impact so that we can operate as efficiently and sustainably as possible. Measuring Up is Brett s own manufacturing, environmental and sustainability auditing system, specifically developed to help us achieve these goals. Quality, Safety, Health and Environmental Management Systems A fully integrated management system QHEST, (Quality, Health, Environment, Safety Together) has been developed to run across the Brett business enabling us to benchmark and continually improve our operational efficiency. The ongoing development of the QHEST integrated management system will ensure that Brett remains at the forefront of system design and compliance. The Group s activities are certified through BSI, QSRMC or SIRA Certification Services. Within Brett Landscaping, we now have the following accreditations in place: BS EN ISO 9001:2008 for Quality Management BS EN ISO 14001:2004 for Environmental Management OHSAS 18001:1999 for Health and Safety Management ENVIRONMENT AND SUSTAINABILITY Our internal sustainability programme extends across land management and bio-diversity, enabling us to take definite and positive steps toward minimising our impact on our surroundings - from quarry restoration to funding of local community projects. We constantly strive to reduce our impact on the environment by minimising our energy usage and maximising the recyclability of our materials, so that they have the minimum impact on the environment both now and in the future. Brett is a lead signatory to the UK Concrete Industries Sustainable Construction Strategy and you can specify Brett hard landscaping systems with the confidence of frequently achieving an A+ or A rating under the BRE Green Guide - depending upon the type of sub-base material used. 14

15 CASE STUDY BRETT PAVING IS SPECIFIED FOR THE UK S LARGEST PERMEABLE PAVING SCHEME The Sixfields development sits on the bank of the River Nene and is part of Northampton Brownfield Initiative - a mixed urban regeneration containing new housing, a rugby club, football pitch and large car parks, as well as a nature reserve. This location boasts the UK's largest permeable concrete block paving scheme, covering 52,000m² and was constructed using Brett's Omega Flow permeable paving to provide a flooding and drainage solution on this environmentally sensitive site adjacent to the River Nene floodplain. Because of the benefits of permeable paving there was no need for catch pits or oil interceptors on the site, as any hydrocarbons would be broken down naturally within the permeable pavement construction layers. This helped to reduce the overall project cost to the client as well as maximise the available space. This site can therefore be seen to have met all the criteria of a SUDS project in terms of attenuating water run off from the site, improving the quality of water leaving the site and enhancing the amenity of the surrounding area. Background Sixfields had been derelict since the 1970s when it was used as a landfill site after previous use for gravel extraction. The site also encompassed a sensitive nature reserve containing a unique habitat for wildlife. The old landfill site was first sealed off with a clay capping layer half a metre thick. This was then compacted using high-energy ground compaction techniques in order to minimise future settlement. The use of Omega Flow block paving was specifically designed to accommodate any future differential settlement. Northampton Borough Council specified traditional asphalt designs and conventional drainage for roads linking car parks on the development. Culverts were constructed under these roads and discharged via interceptors at controlled outfalls. Storm conditions still allowed first flush contaminants to be discharged. A concrete block permeable paving SUDS solution was sought for the construction of the two large car parks. The solution Brett Landscaping advised the client on the advantages of a sustainable drainage solution: Omega Flow. The two main car parks were constructed of 19,000m² and 16,000m² respectively of Omega Flow permeable paving. This would allow rainwater to be attenuated and released at a constant rate through five outfalls into a brook. Finally, 17,000 m 2 of roadway linking the car parks was also constructed using Omega Flow. 15

16 COMMERCIAL SUPPORT Please do not hesitate to contact Brett Commercial Support on for assistance. Our highly trained team are always happy to help if you require further information on any of our products and services - including swatches and samples, installation techniques or expert on-site assistance. ACCREDITED CPD SERVICE Brett offer a range of RIBA accredited CPD presentations. Contact Brett Commercial Support for more information. NBS PLUS SPECIFICATIONS NBS Plus Specifications are available on request from Brett Commercial Support. OTHER BRETT PRODUCTS Brett manufactures and supplies a wide range of landscaping products for both commercial and domestic applications. Call us for more information or advice on standard, made to order or bespoke products. STOCKISTS The majority of our products are available throughout the United Kingdom from our established network of stockists. Contact Brett Commercial Support to locate your local stockist. Brett Landscaping Sileby Road Barrow upon Soar Loughborough Leicestershire LE12 8LX Commercial Support Phone: Fax: