Ethiopia

Legadadi Dam

Engineering for storage plant and urban water supply

Ethiopia

Legadadi Dam

The purpose of the reservoir is to regulate the flows in the Sendafà river, tributary of Legadadi river, and use them for the water supply of Addis Ababa. The dam was built in the 60s to meet the increasing demand for potable water.

“Every day in Ethiopia hundreds of people die because they don’t have access to water”. These were the words uttered by Negus Neghesti, the King of Kings, Haile Selassie, to a very young, twenty-seven-year-old, Giorgio Pietrangeli. With such a professional and moral investiture, the Legadadi project could only have been realized in record time. Legadadi represents an important milestone in Studio Pietrangeli’s history.

Legadadi dam consists of eight different dam types, designed to better adapt to the different geological conditions of the foundation.

The two main dam types, are Hollow Gravity Concrete Dam (main dam) and Bituminous Face Rockfill Dam (saddle dam).

This dam, 44 m high, creates a 40 Mm³ reservoir which regulates the river flows. The released water passes through a treatment plant with a capacity of 50’000 m³/day.

The spillway consists of three bays controlled by flap gates, discharging into a 163 m long chute, which in order to reduce the erosion in the river bed, end with a flip bucket type energy dissipator.

The bottom outlet, located in the dam body, includes twin pipes with a diameter of 900 mm with emergency closure, two guard valves, two regulating valves and two energy dissipating cone valves Howell-Bunger type.

The intake consists of a tower with three inlets at different levels, an artificial gallery crossing the secondary dam and a steel pipe to transfer the flows from the intakes to the treatment plant.