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Last Updated : 2024-04-24 03:13:00
4 August 2017 11:58 pm - 6 - {{hitsCtrl.values.hits}}
Norwegian expert Bent Aagaard who inspected the Uma Oya Multipurpose Development Project that had caused many problems in the Bandarawela area has said that the machinery used for the Project had not been capable of proper strengthening of the tunnel wall and to seal them with strong grout materials.
Mr. Aagaard made these remarks in the interim report submitted to President Maithripala Sirisena at the President’s Official Residence in Colombo today.
Mr. Aagaard said the preliminary studies had not forecast the possibility of large water seepage in the tunnel; “‘Excavation must be done by using suitable machinery on the tunnel wall and grouting all the leaks in the tunnel to ensure that there will be no seepage in the tunnel in the future,’ he added.
He further said the contractors had not been prepared for large scale water ingress in the tunnel. He advised that it would be necessary to get special grout material and machinery before remaining the four and a half kilometer stretch of the tunnel is dug as a part of it is below the residential areas.
He was of the view that a better comprehensive preliminary study could have prevented the water ingress into the tunnel leading to a severe water dearth in some areas.
Meanwhile, President Sirisena said it was regrettable that a series of problems had arisen during the project as the previous government had hurriedly commenced the project without proper study of the feasibility report and the Environmental Impact Assessment (EIA).
The President requested the expert to provide a full report on how the leakage could be completely stopped and the reasons for not taking into the consideration the water leakage in the previous reports; “The government plans to obtain expert advice prior to implementation of the next project in which a 22 Km long tunnel is to be constructed,” he added.
ravin Saturday, 05 August 2017 07:02 AM
Aiyo!! why we wait so long and get specialist to hear not proper machinery used. I remember few of our expert politicians(commission agent of any wrong doings of our mother land ) were making same remark.
G M Jayawardena Saturday, 05 August 2017 08:46 AM
This is a good project indeed; diverting the flowing water to scarcity area while generating electricity. They could have consulted the experts like this to cap the water seepage, especially from the English and French engineers who dig the euro tunnel under the English channel sea. The water and the water pressure above the Uma Oya are nothing compare to the water in the sea and the pressure above the euro tunnel. Once the water seepage is capped the water situation in this affected area will become normal when the area receive the rains. They should not halt the project at this situation as it may cause very sever disasters. As we all know the mountains receive water from the sea through the rains and that water flow back to the sea through the rivers. There cant be any environment issues as certain NGOs claim because diverting only the part of flowing water...The property damage should be compensated.
Haramanis Saturday, 05 August 2017 09:06 AM
With due respect to the Norwegian expert and all.As anybody who has been practically involved in tunnel construction will inform, It is near impossible to determine accurately the ground conditions and water ingress that can be expected in a tunnel that is being constructed several 100's of meters below ground surface. All that can be done during investigations from the surface is to approximately estimate what will occur underground. Drilling investigations for example are mere pinpoints in a long tunnel and will just show the conditions in the immediate vicinity of the hole. Then together with mapping and imagery you can predict - approximately what you might find. What is being emphasised herein is that until you actually open up the tunnel you would not fully know the conditions you will find underground.However once you open up you will need to apply good engineering solutions to deal with water - grouting (may be using different types of material) ground freezing etc,
Bingo Saturday, 05 August 2017 01:33 PM
You sound like a frog in the well. These things are peanut if you travel bit of outside your Island. Typical Islanders mentality cant do anything properly.
Haramanis Saturday, 05 August 2017 08:16 PM
With due apologies to Mr Bingo - who thinks harnessing nature is peanuts!!. The situation at Uma Oya where there is drainage of groundwater into the tunnel can be expected. Simply put, it is like locating a drain along low lying land. Water from the higher.areas will find its way to the drain. In the case of the tunnel, which is being driven through rock, it may cross or run along weak areas (seams, joints or fault or shear zones in the rock) bearing water. The water will then drain into the tunnel. The result will be draining of wells, paddy fields, streams etc being fed by the water bearing seam or joint etc. This happened for example in Samanalawewa Tunnel where the tunnel crossed a water-bearing quartzite seam. It drained all the wells and paddy fields fed by this water.We had to bowser in water to the affected areas.
Haramanis Saturday, 05 August 2017 08:33 PM
Uma Oya contd.Once the Samanalawewa tunnel was lined and grouted up, the water table built up again. Recent visits to Samanalawewa Project area showed all the paddy fields etc as green as ever. Problems - either with water or fault zones have occurred in all the tunnels in Sri Lanka - this is normal. For example Polgolla, Canyon, Kotmale etc. tunnels had geotech problems . The solution is an engineering one plus social and environmental to handle effects on the people and environment. It is interesting that drainage of water into the tunnel (or extraction of water from the ground) can cause large land subsidence - a ground subsidence of 14m has been recorded at Wairakei geothermal field (NZ) due to ground water extraction. This may be the cause of collapse of houses etc. at Uma Oya due to foundation failure. The Project is a good project and should be continued and completed.Overall the effects of construction has not been managed correctly and has become highly politicized.
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