Shortcuts in Construction Lead to Collapse of Sunkishala Intake Well Structure

Hyderabad: The retaining wall of the under-construction intake well and pump house complex at Sunkishala, where work was initiated by the BRS government, has collapsed, affecting plans to create a permanent solution for drawing water from Nagarjunasagar for the twin cities.

The wall collapsed at the Rs 2,215-crore Sunkishala project on August 1 but came to light when an employee put a video of the incident on social media. The wall collapsed during the shift change, and no one was injured. Typically around 100 workers are present at the location.

Sources said the contractor was continuing the work even after water level in the Nagarjunasagar was nearing the full tank level. As entry of one of the tunnels was kept open, the intake well was flooded. This leading to the collapse of the safety wall due to the pressure of the water.

Construction materials including earthmoving equipment and machinery submerged in the water.

The Sunkishala intake well project was stated by the earlier BRS government to be a significant component of the Krishna Drinking Water Supply Project (KDWSP) to supply water to the GHMC area until 2050.

Reacting to the incident. Legislative Council Gutha Sukender Reddy said that there was no necessity for the Sunkishala scheme and he had earlier opposed it. The money spend on the Sunkishala project could have been better spent on the Srisailam left bank canal tunnel, he said.

Inquiries with officials revealed that there were possible deviations in construction sequence of the retaining wall with the agency awarded the work, Megha Engineering and Infrastructure Limited (MEIL), with officials overseeing the project apparently approving the taking shortcuts in the construction process.

The work is being executed by the HMWS&SB and HMDA.

Incidentally, this is the collapse of a retaining wall built by MEIL, the first being the incident at the Lakshmi pump house at Kannepally in July 2022, part of the Kaleshwaram lift irrigation scheme. There too it was revealed by officials that tie beam structural support was inadequate, as these were added later for the same reasons as at Sunkishala.

According to officials, the retaining wall at Sunkishala collapsed as it did not have the required strength to withstand the water pressure from the tunnels designed to draw water into the intake well. The problem arose because ‘tie beams’ – horizontal cement concrete beams in this case – that support the vertical pillars of the retaining wall were not cast simultaneously along with the pillars.

“Typically, the tie beams are cast as the pillars are built. But in this case, the contractor realized that if the tie beams are built simultaneously as planned at 10-metre intervals, its engineers cannot use the booms used to pump and pour concrete to build the pillars as the tie beams would hinder free movement of the booms,” an official explained.

A decision was taken to first build the pillars and then add the tie beams. But before this latter part of the work could be completed, water from the tunnels pushed the retaining wall down, he said.

On whether the deviation from the sequence of construction plans was officially approved, officials were not forthcoming. “The agency said the beams were interfering with speedy construction of the retaining wall crucial for completion of the intake well works, and so it was left to it to figure a way out,” an official said.

Sources in the HMWS&SB admitted that the water board was trying to get the works completed this year as the water level was very low in Nagarjunasagar and that no one anticipated that the reservoir will fill up quickly. Asked if such an eventuality was not considered, given history of how quickly both Srisailam and the Nagarjunasagar could fill up once the monsoon sets in, officials said, “the company thought it can complete the work but it too did not expect the water levels to rise this quickly.”

The project is being constructed at Palthi thanda in Peddavoora mandal to ensure continuous Krishna water supply to Hyderabad for drinking water purposes in the summer. Once this project is completed, the Water Board can draw water from lower than-dead storage level at Nagarjunasagar, something it does now each year by installing temporary pumps.