WET News

20 WET NEWS october 2015 Search for suppliers at wwtonline.co.uk CPM Group Precast concrete drainage www.cpm-group.com cPM 's off-site Solution team offers flood protection products and rainwater and stormwater management systems that include modular tanks, rainwater harvesting systems, widewall chambers and flatpack tanks that are suitable for the water industry. Flood Control International Flood protection www.floodcontrolinternational.com the company is a leading specialist in flood protection, designing, supplying and installing a range of barriers, gates, doors and glazing for commercial, utility and retail applications. Installations are for flood depths up to 4.5m. It also has a range of contamination containment barriers to prevent water course pollution. Inero UK Flood protection www.inero.co.uk the company is an agent for Swedish manufacturer Inero's range of rapid deployment flood protection barriers. the barriers are an alternative to heavy, complicated, time-consuming flood protection systems. McCloy Consulting SUDS www.mccloyconsulting.com It is an independent, environmental consultancy specialising in SUDS, pollution control for environmentally sensitive projects, and Flood risk Assessment (FrA). It is at the forefront of implementation of the design and implementation of SUDS and can count a number of major clients including attenuation and permeable pavement manufacturers and suppliers. UK Flood Barriers Flood mitigation technology www.ukfloodbarriers.co.uk the company specialises in passive flood technologies that require no manual intervention and no power source. these innovative, long-term and cost-effective solutions are in action in the UK and throughout the world, effectively protecting vital assets and communities from the growing risk of flooding. Wickham Laboratories contamination monitoring www.wickhamlabs.co.uk Wickham Laboratories offers a service to monitor contamination resulting from flood and sewage pollution. It uses robust microbiological test procedures to determine the extent of microbiological contamination health hazards and can advise on how to conduct safe and effective clean-up operations. Specifiers file: The kit: D-rainclean Stormwater Management www.storm-water.co.uk Following a review by the regulating authorities, developers at cribbs causeway retail Park on the outskirts of bristol turned to Stormwater Management's D-rainclean bio-remediation drainage channel to prevent contaminated surface water run-off generated by a heavily trafficked car park from polluting the nearby river trym, a delicate ecosystem that is home to a wide range of protected fauna. the initial SuDS proposal for the site, which has more than 12 million visitors a year, was to use a porous pavement that would collect and pass run-off through an oil interceptor before discharging into the river. With such high volumes of traffic and the associated potential for surface contamination, the regulators and planning authority considered that a more robust and effective sustainable drainage solution was needed to minimise any pollution risk. trash screens ecS engineering Services www.ecsengineeringservices rotherham borough council has had new trash screens installed as part of a series of flood alleviation schemes. It contracted ecS to design, fabricate and install two new trash screens on brook Dike to the north of rotherham. the proper design of the screen is essential in order to prevent it becoming a flood risk in itself, and information gained about the location helped to determine the type and size of debris likely to accumulate at the screen. As the ratio of debris length to bar spacing increased, so does the risk of blockage. the first installation required a single tier, three-sided screen with an access ladder and perforated platform fitted with hand railing. the new trash screen offers a much greater surface area for the water to flow through, even if a large amount of debris has been captured, which ensures that the increased water flow can still enter the culvert. the second installation was a much larger, two tier screen designed to fit within the existing concrete wings of the culvert entrance. the design offered a greater surface area than the original screen as well as additional access platforms to allow the collected debris to be removed. A solution: Assessing drainage potential A s part of the government's pledge to tackle flooding in the UK, in April this year it introduced a policy (part of the Flood and Water Management Act 2010) that requires all new developments and redevelopments in England and Wales to have drainage plans for surface water run-off. The new mandatory consideration of Sustainable Drainage schemes (SuDs) is part of a commitment from the government to make better use of the planning system to secure sustainable drainage systems. The primary purpose of SuDs is to mimic the natural 'greenfield' drainage of a site prior to development. This is achieved by capturing rainfall and allowing as much as possible to soak into the ground close to where it fell, through infiltration systems, or slowing down its entry into the watercourse through retention systems. Any pollutants such as metals or hydrocarbons from roads or car parks are reduced, and the water entering the local watercourse is subsequently cleaner. There are many different SuDs features to suit the constraints and design of a site, including green roofs, rain gardens, ponds, wetlands, infiltration basins and swales (shallow ditches). In high density, commercial and industrial developments, permeable paving, attenuation storage and soakaways may be an option. Infiltration As a result of the new policy, new developments will no longer be able to automatically connect to surface water drainage or combined public sewers. In order to manage surface water run-off, developers are being required to implement sustainable drainage, and SuDs will generally replace traditional underground piped systems that use grates or stormwater drains at street level. Capturing rainfall run-off onsite and infiltrating it into the ground (infiltration SuDs) is the preferred method for depends on the site constraints and the requirements of the individual planning authority and the Lead Local Flood Authority. The capacity of the ground to receive infiltration depends on the nature, thickness and permeability of the underlying material and the depth to the high groundwater table. The final proportion of the site drained by infiltration will depend on topography, outfall levels and a suitable drainage gradient. It is important to note that, even if the whole site cannot be drained by infiltration, the use of partial infiltration is encouraged, with the remainder of run-off discharged via other SuDs systems. Drainage potential Drainage capacity will naturally differ between sites, but the impending launch of ESI's Infiltration Maps will help developers assess the drainage potential and the associated design risks for a site, allowing drainage to be incorporated at the master planning stage. These maps will be able to identify how much potential capacity the local area has to receive water (high, medium or low). In some cases further analyses will be required if ground permeability is variable or high groundwater levels may occur. Infiltration into contam- inated land should be avoided and alternative SuDs designs are available to overcome this. Paul Ellis is technical director at ESI managing surface water without increasing flood risk downstream. Design capacity The greatest benefit to general flood risk is if all run-off is infiltrated on site. However, this may not be feasible due to physical and economic constraints in which case infiltration may be considered as a part of an integrated drainage solution. The final design capacity for an infiltration SuDs system SuDS aim to mimic natural greenfield drainage and the use of infiltration maps will help avoid contaminated land, says Paul ellis. Different SuDs features include green roofs, rain gardens, ponds, wetlands, infiltration basins and swales

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