1.1 The growing demand for water in the world increases the need for conserving the available water supply. In open conveyance systems, conservation of irrigation water and reduced maintenance costs through control of weeds and seepage losses can best be accomplished by providing a dependable impervious lining. Nonreinforced concrete lining, which has a high hydraulic efficiency, is a dependable means of water control and seepage reduction in canals. The purpose of this Standard is to provide standards and specifications for the installation of concrete slip-form canal linings in the interest of reducing costs and assuring quality control.

1.2 The use of continuous excavating, trimming and lining equipment is the most economical method for construction of concrete-lined, trapezoidal canals. Available equipment permits construction to practical tolerances in alignment, grade and concrete thickness. The universal acceptance and use of standard trapezoidal canal sections will enable manufacturers to standardize excavating and lining equipment. This will permit a reduction in special engineering and equipment manufacturing costs, will make replacement and service parts readily available, and will result in a net reduction in the cost of completed linings.

1.3 This standard is restricted to irrigation canals that have a bottom width less than 1.8 m (72 in.), and a total depth of lined section not greater than 2.1 m (84 in.). Linings for larger canals usually involve more complex engineering and economic considerations; and they may require special criteria and construction requirements for the canal section, as well as for the lining.

1.4 The wide variance in design requirements by those involved in designing irrigation works prohibits developing criteria for establishing freeboard or foundation treatment. The scope is limited to establishing standard dimensions and shape of the canal section.