The six-member National Dam Safety Authority (NDSA) experts team led by former Chairman of the Central Water Commission (CWC) J. Chandrashekhar Iyer that arrived in here on Wednesday left for Medigadda Barrage after holding an introductory meeting with the irrigation authorities led by Minister N. Uttam Kumar Reddy.
During its three-day visit, the experts are scheduled to Visit Medigadda and Annaram Barrages on March 7 and Sundilla Barrage on March 8.
The team sought preliminary data on Annaram and Sundilla barrages on 19 aspects including barrages layout planning, topographic survey and alternative site selection studies, geological and geotechnical details of foundation strata including borehole log details, SPT results, plate load test results, if any, and others.
Other data/inputs sought by the team includes instrumentation data of barrages – peizometer, stress cells and others till date; details of all distress conditions observed in the barrages till date; drawings of barrages; sectional drawings of the barrages structure showing geological profile; pre-monsoon and post-monsoon inspection reports, EAP and others since the barrages have been added as specified dams by NDSA.
Design calculations of barrages, hydraulic (surface and sub-surface) and stability, safe exist gradient calculation, maximum and minimum stress under raft for various design conditions; foundation improvement work, if any; quality control reports; third-party monitoring reports, if any; physical model study reports, if any, pre-monsoon and post monsoon cross-sections/soundings on the upstream and downstream of the barrages since their commissioning along with actual retrogression.
Relevant clauses of contract agreement regarding defect liability period; completion reports of each block consisting of all components; photographs taken in the upstream and downstream of barrages about cracks marked, if any; drawings showing transverse secant pile cut-off under the double pier and detailing of joining top of piles with pier; condition of all gates and condition of stop log and service gate grooves were also sought.
After returning to the City on March 9 from the field visit/inspection, the experts team will hold another meeting with the authorities of Irrigation Department as well as representatives of contract agencies to chart out the schedule for detailed geological and geo-technical investigation at the site of barrages to find the exact causes for the damage/failure.
