Columbian dam deconstruction a complex challenge

The project, to raise the full supply level of the Urra Dam in the state of Cordoba, required the removal of a 5.2m high section of the existing concrete spillway, and structural modifications to the remaining crest to accommodate fusegates.
DecoTEC’s contract, with dam operating authority Empresa Urra SA ESP, was the first work of its kind by an Australian company in Columbia, and worth an estimated 5% of Australia’s annual export trade with the South American country.
DecoTEC told the dam authority that conventional demolition using hydraulic breakers could cause micro-cracking to the remaining structure and recommended the use of wire-sawing and concrete bursting instead.
“We were able to show the dam’s owners, that this was also the most time-efficient and cost-effective method, as well as meeting their environmental goals,” said DecoTEC managing director Alan Moss.
Application of the wire-sawing involved a series of innovative solutions to complete unusually deep and accurate cuts. “The cross-section of the dam wall was 12m deep and the design called for a fall in the cut profile of 2%, so accurately drilling the hole for the wire was vital,” said Moss.
Access to the work area was difficult and working platforms had to be designed and constructed on both the upstream and downstream faces of the dam.
To maintain vehicle access to the bridge that tops the dam, a 120t crane was set up on the abutments. A series of comprehensive studies were undertaken into the complex rigging requirements involved in using the crane to remove the concrete blocks from under the bridge deck.
Alan Moss said the Colombian project was logistically complicated by the location of the dam on the remote Sinu River.
“As anticipated, the bigger challenges were logistical rather than technical, due to the extreme isolation of the dam, the language barrier and the custom clearance arrangements for importing plant and equipment to Colombia.
“To overcome these challenges required significant co-operation between DecoTEC’s Australian and New Zealand-based technicians, the Columbian employees and the Urra Dam’s project manager.”
Specializing in structural modifications and deconstruction, DecoTEC achieves seamless modifications and controlled demolition, bringing together all project elements - from concept and feasibility through to tooling and implementation.

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