Handling sediments down under4 July 2002
Sedimentation problems can occur for a variety of reasons in different reservoirs and catchment areas. Details are given below of several companies' experiences of dealing with the problem
HYDRO TASMANIA CONTRIBUTES TO OVER 60% of Australia's renewable energy. It owns 27 hydro, one thermal and two diesel power stations and a wind farm.
The company's sedimentation expertise includes working on the Poatina sediment study in the Central Highlands of Tasmania, Australia. The project started in August 2001 and is continuing.
Hydro Consulting provided solutions to sedimentation issues in the Poatina power station intake channel. Based on the company's feasibility study, recommendations to dredge the channel were accepted and detailed design began in April 2002. Dredging began less than one month later. Specific tasks included:
• Determination of geometry and volumes of the sediment.
• Determination of hydraulic properties of the channel
• Design of both a temporary and permanent storage containment facility.
• Environmental reporting.
• General advice and technical response including sediment management, dredge operation, pumping routes, sediment settling properties, containment construction, and access road design.
• On site representation for dredging, containment construction, turbidity monitoring, environmental auditing and stakeholder liaison and management.
Hydro Consulting also worked for Sithe Pacific Development on the San Roque multipurpose project's environmental impact assessment from October 1997 to October 1998. The projects is located on the Agno river, North Luzon, Philippines.
Consulting prepared a comprehensive updated environmental impact assessment including environmental risk assessment (ERA) and
environmental management plan (EMP) to obtain the necessary Environmental Compliance Certificate from the Philippines government.
The ERA including assessing the risks associated with sedimentation of the reservoir formed by the proposed 200m high San Roque dam.
The identified risks were investigated in detail. This involved evaluating the likely geomorphological changes to the Agno river system downstream of the proposed dam and calculating the risk of sediment infilling of the proposed reservoir.