ROADFORD-RESERVOIR - DESIGN, CONSTRUCTION AND PERFORMANCE

Roadford Reservoir, the largest in South-West England, forms a major e lement in the water resources of South West Water. Roadford Dam is for med of 1000 000 m(3) of material, largely rockfill, and has an asphalt ic concrete membrane on its upstream face, Extensive ground and materi al investigations were undertaken in advance of the design of the emba nkment, The reinforced concrete draw-off tower and the bellmouth overf lows were partly constructed by slipform methods, A concrete cut-off l ocated at the upstream toe is extended to a depth of 40 m by a grout c urtain, Construction began early in 1987 and was substantially complet e by October 1989 when reservoir impoundment began, The dam foundation was covered with drainage material before rockfill was placed; the la tter was produced by ripping and dozing to provide a well-graded homog eneous fill. Hydroelectricity is generated from water releases from th e reservoir, Care has been taken to blend the works into the landscape , to preserve the wild life and fishing in the area, and to cater for leisure and recreation needs.