Environmental and Economic Benefit of Subsurface Horizontal Drainage Construction

Abstract

In Uzbekistan, as in other arid regions, land that is irrigated needs drainage. For this purpose subsurface horizontal drainage is widely used. Three methods of construction have been developed such as: trench method with narrow trench, with a wide trench and the trenchless method. Each of these methods influence to environmental condition of soils in a different manner. Most damage is caused by the wide trench method and the least by the narrow trench. For each of these methods the optimal construction cost can be calculated in a similar way. The costs are influenced by local engineering and geologic conditions. These conditions are divided into three groups, according to soil condition in vertical walls of trench as follows: stable and unstable above water conditions and unstable under water condition. In stable soils the most efficient and widely used method is the narrow trench, for which technology and equipment are available, including drainage machine with an active trencher.