Slope Rehabilitation Using ACEMat™ R for the Service Road around Power Plant

The construction of a small hydropower plant in Taiwan lasted five years, during which the slope collapsed, and the service road was interrupted by typhoons or heavy rainfalls for several times, leading to the serious delay in construction schedule. The delayed construction period was up to 7 months, resulting in the Taipower Company several times to extend the construction period. The authority was pushed to actively pay attention to the surrounding environmental safety and raised additional budget for emergency disaster mitigations.

The geological distribution at the site is mainly Lushan formation, which is mostly composed of black to dark gray hard shale, slate, and interbedded phyllite and dark gray hard sandstone. Due to strong developed cleavage, the strength of rock mass is totally controlled by cleavage, leading to steep terrains with highly decomposed and weathered exposed rock in some areas. During the construction, the site had been attacked by a series of typhoons and heavy rains, the most serious of which was Sinlaku Typhoon. Because of the high fragmentation and the poor stability of many slopes along the road, several serious collapses occurred, resulting in the only road connecting outside of the site being washed away. In addition, a large amount of collapsed debris also obstructs the road, causing the interruption of roads transporting construction equipment, materials, and manpower for quite a long time. To catch up with the schedule of the project and minimize the risk of natural disasters in the future, Taipower Company decided to carry out the slope restoration immediately.

Considering the difficult geological conditions at the site and the construction costs of materials and equipment, as well as the needs of aesthetic and ecological protections in mountainous areas, the slope restoration in this case excludes the traditional shotcrete slope protection method. All the damaged slopes were determined to use geosynthetic ACEMat^TM R for rehabilitations. The construction of ACEMat^TM R at the site was easy. It was fixed at the surface of the slope by using anchoring nails. In addition, horizontal and longitudinal drainage ditches were installed to facilitate the discharge of rainwater or runoff on the slope. Based on such arrangement, the resistance to erosion and the stability of the slope have been greatly improved. ACEMat^TM R is flexible and adaptable to the changeable terrain. It can be intimately attached to the slope surface for better surface protection and planting productivity. The lightweight product also helps to reduce the difficulty of construction.

Energy Conservation and Carbon Reduction
During the construction, ACEMat^TM R greatly reduced the needs of transportations for materials and equipment. It eliminated concrete for the construction of soil and water conservation, which achieved an excellent effect of energy saving, carbon diminution and cost reduction. In addition, negative carbon emissions after planting make a particular contribution to the global goal of net-zero emissions. The combination of light green three-dimensional net-like system and the diamond-shape galvanized wire welded mesh has been used to replace the traditional shotcrete slope protection. It has the advantages of fast construction, reduced equipment and manpower consumption, and overall cost saving.

Sustainable Eco-environment
The green slope surface reduces the negative perception compared with exposed decomposed rock by passers-by. In addition, the green landscape of the slope after planting indicated the restoration has been successful. The greening effect of slope surface is remarkable, which is more favorable to the breeding of insects, birds and animals. The ecological environment in the region, therefore, gradually will be recovered and the adverse impact of the project will be reduced to a minimum.

Sustainable Energy Supply
The target power plant is one of Taipower's sustainable power supply chains. A safe and stable service road is mandatory for the completion of the construction in mountainous areas. After the rehabilitation of all damaged slopes in this case, the power plant had been successfully completed. The smooth construction has ensured energy security and also contributed to the management and maintenance of the future operation of the power plant after completion. This is especially true after typhoons or heavy rainfall. It ensures a safe road for the power plant service and guarantee the stability of the sustainable power supply.