Major rehabilitation commences on Toachi-Alluriquín tunnel, Ecuador

6 December 2023

The Electric Corporation of Ecuador (CELEC EP) has initiated crucial repair work on the Toachi-Alluriquín headrace tunnel, a pivotal component of the Toachi Pilatón hydroelectric project. This project, a key aspect of Ecuador's new hydroelectric generation complex, is slated to contribute 254.4MW of power to the National Interconnected System (SNI).

To expedite the completion of civil and complementary works integral to the hydroelectric project, the CELEC EP Hidrotoapi Operational Unit has entered into a contract with the US Army Corps of Engineers. The targeted repair zone within the tunnel spans a 10m section at kilometer 6 + 114. Here, the restoration efforts involve addressing fractured lining, removing compromised concrete, and reinstating affected reinforcing steel. Concrete injections will be executed to consolidate the coating, ensuring the stability of the rock mass in the afflicted areas.

In strategic locations along the tunnel, one-way valves will be installed, facilitating controlled drainage to prevent excessive pressures on the tunnel structure as the repair progresses.

The rehabilitated tunnel is designed to transport water from the Toachi dam to the powerhouse of the 204MW Alluriquín Power Plant. Constructed with reinforced concrete boasting a resistance of 350 kg/cm2, the tunnel spans 8.7km, featuring an internal diameter of 5.6m and a thickness of 35cm.

Upon the successful repair of the tunnel and subsequent filling of the Toachi dam reservoir, the hydroelectric project's hydraulic circuit will be finalized. Coupled with the installation of electromechanical equipment, this ensures the seamless operation of the entire hydroelectric complex, encompassing the already operational 49MW Sarpullo plant (since March of this year), the Alluriquín plant (204MW), and a mini-plant at the dam's base (1.4MW). Collectively, these elements contribute to a total installed power of 254.4MW.

The comprehensive agreement with the US Army Corps of Engineers extends beyond tunnel repairs, encompassing initiatives to enhance dam waterproofing on the Toachi River and address issues such as the repair of the balance chimney. Anticipated to generate 92 gigawatt-hours (GWh) monthly, this hydroelectric project is poised to provide clean electricity to over 670 thousand homes, each consuming an average of 138 KWh per month. This service is expected to commence in the last quarter of 2024.


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