NDSA report not based on investigation, built as per CBIP manual, says Telangana Govt

HYDERABAD: The Special Chief Secretary of the Irrigation and Command Area Development Department of Telangana Dr. Rajat Kumar on Saturday held a meeting with senior officials and engineers about the report of the National Dam Safety Authority (NDSA) on the sagging of a pier of the Lakashmi Barrage which is a part of Kaleshwaram Lift Irrigation Project (KLIP) and replied to the report sent by the chairman of NDSA , Sanjay Kumar Sibal.

“We have studied your comments and suggestions comprehensively and noted that many of them are either unsubstantiated or made without a full appreciation of the facts,” was in a nutshell what the Department had to say about the NDSA’s half-baked report.

First of all the Department said that it was wrong on the part of the NDSA to say that the Irrigation Department submitted only 11 out of the 20 documents required by the six-member NDSA committee. All the documents desired by the NDSA team were shown to the committee during the inspection and subsequent interactive meetings. Subsequently, another NDSA committee letter was received on October 27, 2023 evening requesting to furnish the said 20 documents by October 29. “Though we were given no working days to prepare the reports, which are considerably voluminous, we sent 17 of the documents to the committee through email on October 29.

The Telangana Government said that it was surprised that conclusions had been made about the causes of failure of Lakshmi Barrage without any investigative work by the committee. “As you are aware that, the correct causes can be determined only after proper inspection of the foundation and other related structures, which are currently underwater. Currently a coffer dam is under construction by the agency to divert the water and facilitate the thorough inspection of the affected portions of the barrage. Only once this investigative work is completed, we would be able to assess the correct reasons for the sinking of the piers in the barrage. As such at this point of time, we are unable to agree to your conclusions,” the Telangana Government pointed out.

Negating the point raised by the NDSA that the primary reason for the failure is the settlement of the raft which could be due to various reasons including failure of the upstream secant piles due to barrage load, the Irrigation Department mentioned: “It is to inform that the upstream and downstream secant piles in Medigadda barrage are provided with a flexible joint with the main raft. The prototype for this flexible joint was developed by the Central Water Commission (CWC) and used in the Tapovan project in Uttarakhand. This would eliminate the possibility of barrage loads directly impinging on the piles.”

Further, the secant piling activity was carried out in accordance with the prescribed BIS standards and other relevant guidelines. The alignment of secant piling on upstream and downstream of blocks and cross cutoffs in double piers was done by constructing the RCC Guide wall. RCC Guide wall is constructed all along the alignment of secant piles, the primary secant pile of PCC is driven alternately leaving the RCC Secondary Pile. The verticality was observed on the pile driving machinery provided with a dial gauge for ascertaining the verticality. Secant piles are driven through the Guide wall by maintaining the verticality and no deviation in verticality has been observed in the Guide wall as no damage occurred during the driving of Secant piles.

Additionally, the secant piles are provided with pile caps that were connected with a connecting slab between the pile cap and raft junction by providing the copper water stopper and rubber water stoppers as per extant guidelines. The gap between the pile cap and rafts was water-tightened by providing water stoppers at junctions. The materials used in the Secant piling were tested regularly as per IS codes for Cement, Coarse aggregate, Fine Aggregate, and Steel in the field labs and the Cube Compressive strengths are done for 7 days and 28 days, the acceptance criteria for different grades of concrete are carried out as per the IS 456 and IS 10262.

Followed stringent quality control

“We would also like to emphasize that stringent quality control checks have been conducted while executing of the Secant piles and plinth connection between Raft and cutoff. The tests conducted for Secant piles and Raft are herewith enclosed. We therefore are the opinion that your comments related to poor quality control during project execution are unsubstantiated,” the reply said.

The barrage has been designed as RCC raft duly following the IS Code 6966 - Part 1(1989) and CBIP Manual No 179-Volume 1 & 2. The stilling basin floor is designed as RCC raft duly considering the uplift pressures. Pressure Relief Valves are also provided as a drainage arrangement in the stilling basin to relieve the uplift pressures on stilling basin raft.

“Detailed modeling studies have been done jointly with IIT Hyderabad. The final recommendations are here with enclosed for your kind perusal and we would be happy to receive your specific comments on them, if any. However due to the continuous rains in the basin and flows in the barrage for the last 3 years, an opportunity to implement the modification was not available till date,” the Telangana Government said.

Taking the attention of the NDSA ti the eighth para of irs report the Irrigation Department said that the letter had made certain observations regarding non-observance of NDSA provisions by the concerned authorities. “In this context, we would like to inform though Dam Safety Act was effective from 13.12.2021, the regulations made thereupon did not provide clarity regarding the height and other details of the specified structures. The Telangana SDSO has sought several clarifications from NDSA in this matter. As a matter of fact, the NDSA has appreciated the role of the Telangana SDSO in the development of the revised guidelines. As per these clarifications, Medigadda, Annaram and Sundilla Barrages were included to the List of Specified Dams only on July 12, 2023.

Since the inclusion of Medigadda Barrage to the updated list was in the month of July 2023, pre-monsoon inspection could not be carried out. Other inspection reports as required under the Act were already submitted and the post-monsoon inspection would be carried out in November 2023. “We assure that all the provisions of Dam Safety Act 2021 are being scrupulously complied with.

Full operations after restoration

The suggestions made were already known to the dam authorities and as explained to the committee during the meeting, action on restoring full operations of the barrage had already been initiated. Operations of the barrage would start after the agency rectifies the damages.

Annaram and Sundilla

“The comments pertaining to Annaram and Sundilla barrages are unsubstantiated as the expert committee did not even visit the two barrages. However, we assure you that both the barrages are included in the list of specified dams under the NDS Act and the SDSO is taking all the necessary measures to fully comply with the provisions of the Act,” the Telangana Government said.

“We would like to submit that diversion structures such as barrages are subjected to multiplicity of loading conditions like the surface flows, sub-surface flows, uplift pressures, scours and exit gradients, tail water level etc. These challenges individually and collectively are considered in the design process for Medigadda barrage in various combinations. The BIS have published 3 codes specifically meant for various aspects related to the Design of Barrages in addition to guidelines on various related aspects like Cement, Concrete, Steel, etc that are used in the construction of Barrages. Further, the CBIP had also published manuals on Barrages in two volumes to support for deeper understanding. The CDO of Telangana state, which is considered as a premier institution of the country, has diligently followed the said guidelines cited above for all the Projects, more specifically for prestigious projects like Kaleshwaram. The Irrigation Department of the State is also known for it’s excellence and the world-renowned structures like Nizamsagar, NSP, Srisailam, Pochampad etc are the pride of the nation.”

Approved by Jal Shakti Ministry

The Kaleshwaram Project was approved by the Technical Advisory Committee of the Jal Shakti Ministry on June 6, 2018 after thoroughly examining all the aspects like Hydrology, Costing, Irrigation Planning, environmental clearances etc. In particular, the design of the barrage was extensively studied by the Costing Directorate of the CWC with respect to functionality and costing. The then Chairman of the Central Water Commission, S. Masood Hussain along with CWC Chief Engineers visited Kaleshwaram project on April 9, 2018. The Chairman appreciated the Telangana government for the speedy execution of work and said that they had not seen any irrigation project of such magnitude and described the project as an “Engineering Marvel”.

Further, the completion of the Kaleshwaram project, had tremendous positive impact on the economy and ecology of the state. Agriculture production in the state has increased by 300 percent. The average groundwater level has increased by over 7 metres due to supply of surface water for irrigation and recharging of underground aquifers. A tremendous growth was seen in the fisheries and tourism sectors. The overall positive impact of Kaleshwaram Project has resulted in Telangana leading in India with the highest per capita income of Rs 3.17 Lakhs, up from about 1.28 lakhs at the time of the formation of the state.

“We therefore request you to cooperate with the state agencies in the speedy and effective restoration of this prestigious and beneficial project in a purely professional manner without any extraneous considerations, as this would be of tremendous,” the reply concluded.