The crucial and the most difficult diaphragm wall has been built across 1396.60 metres stretch (length). With a width of 1.5 metres and going to depth of 95 metres (at some points) into the river, the diaphragm wall has been built with a great strength. It’s learnt that the construction has been done from the depth of 2 metres below the discovery of the stones under the depth of river which is a herculean task.
The diaphragm wall built to eliminate seepage below the dam in order to minimise water loss and increase stability will make the Polavaram Irrigation Project (PIP) unique.
This diaphragm wall will serve as the foundation for the Polavaram Dam with stone and clay and will be built 150 feet above the diaphragm wall. The diaphragm wall was an underground sealing (cut-off wall) for water retaining structures. Water tightness, plasticity and erosion resistance were the most important criteria. The whole Polavaram Dam has the capacity to store 194 TMC water. Polavaram will be the first major irrigation project in the country to have a diaphragm wall.
The work of the diaphragm wall has been launched by Chandrababu Naidu on Feb 1st, 2017 and the whole diaphragm wall was built in two seasons (two summers) with officials, workers worked very hard for 412 days to complete it before the time. The whole cost of the construction is estimated at Rs 430 crore.
The contractors, L&T, and German engineering company Bauer has made it possible. On Sunday alone, 8500 cubic metres of concrete work was done and thus marked its completion. AP CM Chandrababu Naidu is going to visit today.