Abstract

Su-Pan 1 is a small hydropower project with installation capacity of 30 MW, maximum water head of 250 m, and maximum discharge of almost 17 m3/s. The project is located in SaPa district, Lao Cai province, Vietnam, and in outskirt of a national protected forest (Hoang Lien forest).

After due considerations, it was found that underground solution is an optimum solution for the project from both environmental and economical point of view. The project was built with 2740 m headrace tunnel, underground powerhouse, and 415 m tailrace tunnel. The project was successfully put in operation in December 2018 and in good production since then.

This paper presents practical experiences during the design and construction of the project, particularly focuses on the rock engineering issues including rock mass evaluations and rock stress measurements. Experiences learned from this project can be used for similar hydropower projects in future.

Introduction

Su-Pan 1 is a small hydropower located in four communes Su-Pan, Hau Thao, Ta Van, Ban Ho, belonging to Sapa district, Lao Cai province, Vietnam. Main features of the project are installation capacity of 30 MW (two units), maximum water head of 250 m, and maximum discharge of almost 17 m3/s. The project consists of a concrete arch dam with maximum height of 52.5 m, a headrace tunnel of 2.7 km (tunnel width D = 4 m), underground powerhouse, and tailrace tunnel of approximately 0.4 km. The project was competed and commissioned in December 2018 (first unit), and January 2019 (second unit).

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