Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/391624
24 WET NEWS OCTOBER 2014 With around one million properties unable to connect to mains sewers, Geoff Oakley reveals why engineers must think within legal frameworks. The challenge: Ensuring safe and legal off-mains drainage Sewage treatment plants should be considered as the preferred default solution T here are an estimated one million properties in the UK that cannot readily connect to the mains sewer to support the sanitary facilities within the building. Each property will present engineers with a unique set of challenges pertinent to the demands of the specific site, building use, and facilities, all of which must be addressed within legal frameworks to avoid the risk of prosecution. Before drainage is installed, the site should be subject to an inspection in accordance with both 2010 Building Regs and the DETR report 3/99. The inspector must address a number of issues including: • Managing all effluent safely, legally, and avoid- ing any instances of local pollution • Connecting to the mains if at all possible • Dealing with foul water within the boundaries of the property if necessary • Sizing/specifying the solutions correctly based on the type and volume of waste, as well as other variables such as seasonal loading A sewer connection for the building requires sufficient gravitational forces to move the waste to the sewer; if gravity is insufficient then waste will need to be pumped to the sewer using a suitably sized pump sta- tion in accordance with Build- ing Regs. Only if any connection is deemed to be impractical will the next best option, a private drainage solution, be explored. Whichever route is finally decided upon, the solution must be correctly specified to suit the application in order to avoid the unappetising pros- pect of overflowing toilets and drains – either of which could lead to the property owner and the builder being prosecuted under The Public Health Act 1936. Commercial waste considerations Waste from commercial appli- cations is produced from a vari- ety of sources and will vary in strength, dilution and quantity, all of which will need to be taken into account. To illustrate: "Most commonly, people miscalculate the depth of the incoming drain and fail to accurately measure the distance and height to the main sewer into which they're planning to pump." THE CONCEPT • Kingspan Klargester Envirosafe sewage treatment plants employs a three-stage process, featuring an innovative plug flow combination of aerobic and anoxic processes in a fluidised bed arrangement • Process is self-establishing and does not require the addition of cultures or chemicals • Engineered to manage a wide variety of applications and discharge qualities • Maintains optimum performance despite shock organic loadings and hydraulic surges • Detrimental effects of modern disinfectants and cleaning materials are minimised NEED TO KNOW Low profile covers for minimal visual impact Delivers more than 90% pollution removal – maximum efficiency Certified to European standard EN12566 part 3 – high performance guaranteed Control panel issues an immediate alert should a problem occur THE VERDICT Environmental standards are becoming more demanding in the UK. Envirosafe has been designed to deliver flexible, high performance criteria enabling it to adapt to projected future demand. Further, it offers a high performance plant of up to 300 PE for sewage treatment in domestic and commercial applications in a single tank. This is a great move forward in reducing both physical and carbon footprint. • INSIGHT DRAINAGE Each property presents engineers with a unique set of challenges. Each site should be inspected before drainage is installed • Staff toilets or public washrooms will have rela- tively high waste strength, as the foul water will have no additional dilution from, say, showers or washing machines • Commercial kitchens may require a grease trap to avoid blockages • Holiday camps or visitors centres will both have sea- sonal fluctuations in loading Hotels, pubs and clubs may require more detailed and com- plicated designs depending on a number of variables. For example, the design of a system for a hotel needs to con- sider some or all of the follow- ing: star rating, market / type of customer, meal provisions (breakfast, lunch, dinner), event catering (weddings, busi- ness conferences), leisure facili- ties, bars, restaurants and style of food served, and laundry requirements. It may have twin / double rooms, or cater mainly for young families.