- Water released through spillway to the delta
- Godavari River diverted to 6.6 km
POLAVARAM, India, June 11, 2021 /PRNewswire/ — The first step towards the realising decades’ old dream of the Polavaram Project finally took place today by initiating the water releasing through the spillway. By removing the ring bund, the Godavari River diverted to spillway through the approach channel. Under the supervision of state water resources department officials, Megha Engineering and Infrastructures Limited (MEIL) engineers successfully executed this critical exercise. Mr Alla Nani, Deputy Chief Minister and Minister for Health and Mr Anil Kumar, Minister for Irrigation participated in the even virtually. Mr Narayana Reddy, Engineer-in-Chief, Mr Sudhakar Babu, Chief Engineer, Polavaram Project, and Mr Ranga Rajan, Associated Vice-President, MEIL, were present. The officials conducted a traditional pooja on this auspicious occasion.
Speaking on this occasion, “We have achieved an important milestone by releasing the Godavari water to the downstream through the approach channel. This is the crucial development in the construction of the Polavaram Project. By Overcoming the heavy floods and Covid crisis, we have achieved the targeted works as per schedule. To meet the government’s target to provide water to the Kharif season from June 15, we have executed the diaphragm wall at the earliest and closed the cofferdam. We constructed the approach channel, spill channel, spillway in the toughest times,” Mr Ranga Rajan, Associate Vice-President, MEIL, said.
Progressing at a Brisk Pace
The spillway, three gaps (ECRF 1,2,3), hydropower plant and the water transport works are crucial in constructing Polavaram Project. MEIL has completed the spillway at a brisk pace under the engineering principles (work manual and protocol). The approach channel, spillway gates, spill channel and pilot channel work was almost completed in the current season. Because of these constructions, the cofferdam was able to stop the Godavari River flow and the Godavari delta did not get the water from the upstream.
From now onwards, both Godavari districts, Tadipudi, Pattiseema, Pushkaram and other Godavari delta areas, will get the irrigation and drinking water through the approach channel. Until recently, these areas used to get the water through natural river flow. The Godavari River flows between June to December period and large-scale floods occur during August, September and October months. Godavari receives water from the Sileru and Machkand hydropower plants in summer and reaches the Godavari delta at a minimal level. The water diverted through the approach channel from today merges with the Godavari again through the pilot channel.
The water level in the Godavari is rising after the closure of the upper cofferdam. The submerged villages were evacuated and provided rehabilitation. The meteorology department is expecting heavy rains in the Godavari tributary Sabari River catchment area. As monsoons have already actively spread, heavy rains in Chhattisgarh, Odisha and Sabari, Pamuleru catchment areas are expected. In such a case, the water should be diverted over the spillway. Even if there is no major flood, we need to divert the water into the Godavari River through an approach channel, river sluice and pilot channel to cater for the needs of the Godavari delta.
It is inevitable to avoid water shortage for Kharif season. By removing the temporary bund at the beginning of the approach channel, the Godavari River flow diverted to the right side for 6.6 kilometers. This will release the subsequent heavy flooding to downstream by lifting the radial gates. With today’s water release, it will be easier to take up the earth cum rock-fill dam works at the Gap -2. This is the reason MEIL has sped up the upper and lower cofferdam construction works.
An Engineering Marvel: The 6.6 km River Diversion
The most volatile river Godavari’s diversion for 6.6 kilometres has completed. The second largest river in the country experiences floods ranging from 35 lakh to 50 lakh cusecs. Diversion of these massive floods for 6.6 kilometres is not an easy task. It is an engineering marvel on any parameter. The Godavari River’s natural flow, diverting to the right side, will continue even after completing the project.
Three gaps to be constructed in the middle of the river, Earth Cum Rock Fill (ECRF) dam, also called Gap-2, are the largest. This ECRF dam can withstand the pressure of the 50 lakh cusecs flood. To construct this vital structure, the upper cofferdam has become a necessity. The length of the approach channel, spill channel and pilot channel is 6.6 km. These structures are built parallel to the right side of the main river. The approach channel was built up to 2.4 km towards the spillway. The spill channel is 3.1 km from the spillway, and the pilot channel is 1.1 km from the end of the spill channel. The upper cofferdam was constructed 2480 metres long and 42.5 meters in height, and three gaps. MEIL has filled the upper cofferdam gaps as per the government decision. As a result, even 30 lakh cusec flood flows through the approach channel and the construction work will not be obstructed.
The fastest execution of works
Megha Engineering and Infrastructures Limited (MEIL) have completed the work required to divert the Godavari River flow in a record time. To turn the Godavari to the right and reach the spillway, excavating the approach channel to 2.4 kilometres was necessary. It looks like another river. Of the 1,54,8800 cubic meters of earth excavation, MEIL completed 1,04,88,00 cubic meters. Out of 5.92 crore cubic meters of earthwork, 5.24 crore cubic meters is already completed. The works are progressing round the clock.
Of the total CC blocks (spillway) of 17 lakh cubic meters, MEIL completed 15.17 lakh cubic metres. The crucial spillway can regulate 50 lakh cusecs of flood and releases to the downstream. It is larger than the Three Gorges Dam, which can regulate only 47 lakh cusecs. To withstand the flood pressure, the world’s largest gates erection and 15.17 cubic meters of concrete work was completed. To operate the gates on the hydraulic method, 22 power packs to 44 gates were fixed. 28 Radial gates were raised to release the flood in this season.
So far, 76.29 per cent of project headworks was completed. Many villages, including Polavaram, are at risk of flooding as water diversion takes place through an approach channel. Up to one lakh cusecs of floods in the spillway will not have any adverse effect. However, flood above 12 lakh cusecs will have an impact. Flood at a minimum level will affect nine habitations. As the flood increase to 28 meters high, the flood-prone habitations will increase. If the flood reaches the spillway level (45.72meters), about 235 habitations will be flooded. Accordingly, the government is preparing a plan and rehabilitating the villages.
Megha Engineering and Infrastructures Ltd. (MEIL) established in 1989, is one of the fastest growing infra companies in India. Over the years, MEIL has constructed numerous structures like large civil constructions, oil and gas pipelines, pump houses, large water treatment plants, dams, reservoirs, power transmission lines, power generation units, tunnels – and all of them have an important role to play in improving the quality of life of the common man for many years into the foreseeable future.
For more information, please visit: https://www.meil.in/