Ertan Dam | Trevi

Sichuan Province – P.R.CHINA

Ertan Hydroelectric Project is one of the most important hydropower projects carried out by Trevi, located on the Yalong River in the South of China (Sichuan Province). The associated underground power station, where 6 generators are allocated, is able to produce energy of 3,300 MW.

Trevi Construction Co. Ltd. Hong Kong (belonging to Trevi S.p.A. Group) has been awarded two sub-contracts. The first (Lot A) consists in the execution of an impermeable cut-off wall into alluvial soil for the upstream and downstream cofferdams. The second contract (Lot B), which is the subject of this brochure, comprises the consolidation, impermeabilisation and drainage of the rock for the dam foundation. For the execution of works, Trevi cooperated with a Chinese specialized contractor “The 8th Hydroelectric Engineering Bureau of Changsha” (Hunan Province).

Owner	Ertan Hydroelectric Develop. Corp. (P.R.China)
Contractor	ERTAN JOINT VENTURE
Duration of work	1993 – 1994 (Lot A) 1994 – 1998 (Lot B)

The Ertan Hydroelectric Project (Arch Dam Works-Contract No. ET/IC1- Lot 1) has been executed by the Ertan Joint Venture formed by Impregilo S.p.A. (Sponsor), a local company, the Eight Hydroelectric Engineering Bureau, Dumez, G.T.M. and Torno S.p.A.

The owner is Ertan Hydroelectric Development Corporation and the dam design has been worked out by Chengdu Hydroelectric Investigation and Design Institute, Ministry of Energy and Ministry of Water Resources, of Peoples Republic of China.

The main features of the structure and reservoir of the Arch Dam are:

¥ Height: 240 m.
¥ Volume of concrete: 5 millions cu.m.
¥ Design flood discharge: 20,000 cu.m./sec.
¥ Reservoir storage capacity: 5.8 billions cu.m.
¥ Maximum head of water: 189.2 m.
¥ Annual output: 17,000 GWh

The Project includes two earth and rock cofferdams across the Yalong River, which allowed the excavation of the concrete Arch Dam foundation.

The two cofferdams, designed by the Ertan Joint Venture, are 62 m (upstream cofferdam) and 30 m heights (downstream cofferdam) and comply with the traditional design for earthfill dam with a central core in clay interned by coarse quarry materials (rip-rap). Peculiarity of the two cofferdams is that it is one of the first projects in the world having an impermeable cut-off made of Jet Grouting columns executed with the bi-fluidw method (Lot A).

A further feature which makes the Ertan Hydroelectric Project such an important work is the impressing impermeable curtain grouting and drainage curtain of the rock of the arch dam foundation executed on the basis of avarious and complex galleries pattern