|
Simplified sewerage, also called small-bore sewerage, is a sewer system that collects all household wastewater (blackwater and greywater) in small-diameter pipes laid at fairly flat gradients. Simplified sewers are laid in the front yard or under the pavement (sidewalk) or - if feasible - inside the back yard, rather than in the centre of the road as with conventional sewerage. It is suitable for existing unplanned low-income areas, as well as new housing estates with a regular layout.〔(Simplified Sewerage Design Manual, Duncan Mara, Leeds University )〕 It allows for a more flexible design.〔Tilley, E., Ulrich, L., Lüthi, C., Reymond, Ph., Zurbrügg, C.: (Compendium of Sanitation Systems and Technologies - (2nd Revised Edition) ). Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland, 2014〕 With simplified sewerage it is crucial to have management arrangements in place to remove blockages, which are more frequent than with conventional sewers. It has been estimated that simplified sewerage reduces investment costs by ''up to'' 50% compared to conventional sewerage. Simplified sewerage is sometimes also referred to as conventional sewerage with appropriate standards, implying that most conventional sewers are overdesigned. The concept of simplified sewerage emerged in parallel in Natal, Brazil and Karachi, Pakistan in the early 1980s without any interaction or communication. In both cases particular emphasis was given to community mobilization, an essential element for the success of simplified sewerage. In Latin America, and particularly in Brazil, simplified sewerage is also known as condominial sewerage, a term that undercores the importance of community participation in planning and maintenance at the level of a housing block (known as ''condominio'' in the Spanish and Portuguese use of the term). == Background == In developing countries, connection to sewer systems is often costly for poor households, despite typically low monthly sewer tariffs. This apparent paradox is explained by the high costs of in-plot and in-house sanitary installations that have to be paid entirely by the user, by sometimes high sewer connection fees levied by utilities, and by a lack of community consultation. As a result, in many cities in developing countries conventional sewers are laid at high costs under a street, while many users on that street do not connect to them. In Brazil, in some cities connection rates in the early 1990s were less than 40% of the intended beneficiary population.〔 *Gabrielle Watson: Good Sewers Cheap? Agency-Customer Interactions in Low-Cost Urban Sanitation in Brazil, The World Bank, 1995, p. 7〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「simplified sewerage」の詳細全文を読む スポンサード リンク
|