Asks agency to provide comprehensive rehab plan to save barrage
Hyderabad:The irrigation department, in a strongly worded letter to L&T PES-joint venture (JV), has asked the agency to stop cherry-picking the contents in the National Dam Safety Authority (NDSA) report on Medigadda and other Kaleshwaram project barages, accept that it did not provide documentation or seek approvals for the quality of concrete used, and focus on providing, as instructed, comprehensive rehabilitation proposals to save the Medigadda barrage.
The department also said “it may be appropriate” for the company to “accept the (NDSA) report” and furnish the proposals not just for the damaged Block 7, but for the entire Medigadda barrage. This, the letter dated May 31, said is to “safeguard the structural integrity of the barrage and protect lives and livelihood of dependent communities.”
The department’s letter also warned that inaction in taking up rehabilitation measures could result in damage similar to Block 7 — which had partially subsided with some of its piers developing serious cracks —in “other blocks of the Medigadda barrage as similar failures cannot be ruled out.”
The company was told that it failed to follow the ‘method statement’ with respect to quality control, particularly with reference to constructing secant pile cutoff walls which are ‘vital subsurface components of a barrage,” indicating that this resulted in formation of holes, and the ultimate serious damage to Block 7 of the barrage.
It said the company did not provide any documentation to show that it received approvals from “the competent authority in the irrigation department,” on the concrete mixes it used. This, it said, “resulted in uneconomical concrete mix for various grades of concrete on account of increased cement content, besides increased heat of hydration of concrete,” which in turn, may have impacted the “integrity, water tightness, and other parameters” of the cutoffs.
The irrigation department further accused the company of cherry-picking from the NDSA report saying “the agency has not considered the entire report but only commented on issues favourable to them.” It said the company’s comments with respect to the NDSA report on aspects related to ‘lack of quality control in execution of the work’ were ‘controversial’, the department said, and that L&T should see the NDSA report in its totality.
It said the Pt. No. 13 in the NDSA report’s executive summary, that the company cited in its letter, also pointed out the existence of holes near piers 20 and 21 of Medigadda and in the downstream cutoff near pier 17. “These played a significant role in formation of piping,” the department told L&T referring to the holes formed in the sand under the foundations.
It also pointed out that NDSA said that in Annram and Sundilla barrages, the primary reason for formation of holes in cutoffs was the inherent weakness of the RCC/PCC piles, and quality of construction of secant piles. The letter said the same reason “may be” applicable to Medigadda barrage also. The agency “instead of analyzing the reason for holes in the cutoffs, on the contrary reported inconsistencies in the NDSA report,” the department’s response pointed out.
Dismissing the concerns raised by the agency, the department said the NDSA report, prepared by its expert committee, followed “taking a collective view after examination of records, designs, and drawings submitted by the I&CAD department, and concerned stakeholders and agencies.”
The department made it clear it was now up to L&T PES-JV to not only submit comprehensive rehabilitation plan for the Medigadda barrage, and also ensure safe disposal or stabilization of the damaged Block 7 without the work impacting the adjacent Blocks 6 and 8 of the barrage.
Infograph
What L&T PES-JV said:
Quality control manual submitted to irrigation demartment on 14-7-2016.
Method statement given during construction, protocol followed.
Quality checks proofs submitted regularly, department gave quarterly satisfaction reports;
Third party test for materials, design mix by third party labs.
Irrigation department response:
No record to show method statement given by agency was agreed to by the department.
No proof of concrete mix designs verification at site, or irrigation concurrence, before starting, or during construction.
Agency picked points suitable to it, not entire NDSA report.
Poor construction at Annaram, Sundilla 'may be' applicable to Medigadda.
