The vibrant small hydro power industry in Sri Lanka saw a further green accomplishment in the south of the country approximately 2km from Dehilanda in Wellawaya at the river Kuda Oya. With a capacity of 1.2MW and approximately 5.7GWh output per year, which will be fed into the national grid of Sri Lanka water, the hydro power plant will supply water to about 6,000 households. The owner, the private company Wellawaya Hydro Power, opted for a sustainable and environmentally sane penstock solution with Hobas CC-GRP pipes.
Centrifugally cast glass fibre reinforced plastic (CC-GRP )pipes were installed in Sri Lanka for a penstock solution to supply about 6,000 households with water. (photos: Hobas)
Environmental considerations played a crucial role in the decision making process for the most suitable pipe material. “Since the plant is situated in the jungle, we wanted to make sure to best protect flora and fauna. We decided to bury the penstock because it would have otherwise crossed and divided animal trails,” says Roshan Prabatha Wickramasinghe, Director of Wellawaya Hydro Power. Thanks to the possibility of optimally adapting the line to the terrain, only a 3m wide section had to be cleared for trenching. The tested and approved method of angular deflection accommodated in the couplings as well as angular cut pipe ends reduced the number of bends required.
Pipeline installation
The construction of the 1,460-m-long glass fibre reinforced (GRP) pipeline leading to the turbine at a head of 95m commenced in 2011. Hobas delivered pipes designed for different pressure classes ranging from PN 1 to PN 12.5. While gravity pipes were utilised for flatter parts of the route, pressure pipes were installed in especially steep sections, where the comparably light pipe material benefited pipe transportation and handling considerably. Some parts are in fact so steep that a mechanically operated winch had to be employed to pull the pipes to the trench. “This would have proved very difficult if not impossible with other pipe materials which are heavier by far,” adds Wickramasinghe.
After 18 months construction time the pressure test was conducted and successfully passed so that the plant could be put into service. Shrubs and trees were quickly replanted along the backfilled trenches so that soon there will be no trace of construction works and nature can take its usual course. Not only is the operator content with the result but also the villagers: Apart from electricity, locals got the opportunity to be trained and to operate the hydropower plant.
Year of construction 2011 – 2013
Construction time 18 months
Total length of pipe 1,460m
Diameter DN 700 – 1,100
Pressure class PN 1 – 12.5
Stiffness class SN 5000 and 10000
Head 95m
Capacity 1.2MW
Installation method Open trench
Client Wellawaya Hydro Power (Pvt) Ltd
Designer Munex (Pvt) Ltd
Construction company Dolphin Marine Lanka (Pvt) Ltd
Sri Lanka offers good opportunities for hydro power
Hydro power has played a major role in electricity generation in Sri Lanka since the commissioning of the first hydroelectric power plant in 1950. Due to the country’s humid climate conditions and its hilly terrain, Sri Lanka offers good opportunities for generating hydroelectric power both through larger government-owned and private small hydro power plants. In 2012, a new small hydro facility was put into service at the river Wewa Ganga in the village of Kokawita, close to the city of Kalwana in the southwest of Sri Lanka. The pipe system supplies 1,000 households with green energy.
478m Hobas GRP pipes DN 2,000 to 2,200 were laid in the rich green rain forest.
www.hobas.com
