ABSTRACT
Production and drainage facilities include production wells, collector wells, galleries, construction dewatering well-point and deep well systems, drains, and mines. Well efficiency is specified for a particular pumping period duration and is defined as the actual production well specific capacity divided by the theoretical production well specific capacity. Galleries are horizontal groundwater supply facilities consisting of open trenches, ditches, buried conduits, buried drains, or tunnels. A production well sometimes encounters several layers of sand and gravel having different grain sizes and gradations. The spacing of production wells is often dictated by practical considerations such as property boundaries and existing distribution of pipe networks. Economically speaking, the farther apart production wells are spaced, the less their mutual interference but the greater the cost of connecting pipeline and electric equipment. Design and construction techniques for water supply production wells apply to deep wells used for dewatering. Underground drains are either placed above the aquifer base or rest on the aquifer base.
