Son La Dam,
​Vietnam

Geomotion Chosen to Supply Instrumentation to South East Asia's Largest RCC Dam

The $3.5 billion Son La project is under construction approximately 360km north west of Hanoi. It is a 138m high structure with RCC volume of approximately 3.1M m3, with a peripheral spillway with a capacity of 35,000m3/s. Located on the right bank, the spillway has eight gates in addition to 16 low level gates to control water levels during the flood season.

---

Overview

The client is EVN of Vietnam, the lead consultant is PECC1 with the sub consultant Colenco Power Engineering of Switzerland. Geomotion work with their Distributor Viettronics Dong Da, JSC who will be carrying out the installation of the monitoring system.

Son La is considered to be of national importance and will supply 9GWh annually to the grid. River regulation will also enable the 1980MW Hoa Binh plant, which is downstream, to operate fully. Coincidentally Geomotion also supplied instrumentation to the Hoa Binh Dam in the early 1980's.

Son La is the second of four dams to be built on the river and is an integral part of the largest hydropower project currently under construction in south east Asia. Upon completion the whole scheme will have an installed capacity of 6,532MW and will provide flood control, water supply and regulation.

Purpose

Compared with conventional gravity and concrete face rockfill dams (CFRDs), RCC dams are generally the preferred choice of designers when working in the tropical conditions experienced in south east Asia, especially as the dry season can last only about six months.

The multi purpose dam situated on the Da River is to serve four purposes:

1. Protection from overtopping of the Hoa Binh embankment dam in extreme flood conditions
2. Annual flood peak attenuation downstream
3. Enhanced downstream dry season flow regulation
4. Annual average generation of 9500Gwh

Construction of Son La dam is on a tight schedule, though, because of the need to improve flood control on the Da river. The significant number of flood events that occur each year during the wet season means that river diversions must be able to handle large floods.