Judicial review on technical matters is limited to instances of illegality or irrationality, emphasizing deference to expert opinions.

JUDGMENT Syam Kumar V.M.,J.

This writ petition is filed by the petitioners, inter alia, for a writ of mandamus directing the respondents to stop the sand and silt removal in the upstream and downstream areas of the Moothikayam Regulator cum Bridge (RCB) across the Thoothapuzha, and seeking ancillary reliefs. 2. Placing reliance on Ext P6, a letter issued by the Executive Engineer dated 17.07.2025, wherein the Executive Engineer has suggested the constitution of a technical committee to conduct a technical inspection regarding the allegations of defects in the construction of the RCB, it is submitted on behalf of the petitioners that the said letter confirms the apprehensions raised by them in the W.P.(PIL) thus necessitating issuance of directions as sought for. The statements in Ext. P6 letter, especially regarding the necessity to identify the Temporary Bench Mark (TBM) used for calculating the Maximum Flood Level, and the fact that the TBM recorded 12 years ago is currently unavailable due to changes in the area, including the floods of 2018–19, have purportedly lead the Executive Engineer upon examining the design drawing provided by the IDRB and the construction drawing provided by the KIIDC, to conclude that there is a difference of approximately 2 meters from the solid rock at the bridge’s foundation level to the bridge’s deck slab. This, it is submitted, substantiates the petitioners' apprehension of the possibility of flooding arising from the construction of the RCB.

3. We have heard the learned counsel appearing for both sides.

4. We note that the second respondent/KIIDC has filed a detailed counter affidavit, wherein paragraphs 18 to 22 deal with the specific aspect pointed out by the Executive Engineer in Ext.P6. It reads as follows:

“18. The objective of the de-siltation project is to restore the regulator structure to its intended capacity and ensure the effective functioning of the shutters. In addition, the desiltation process will not go below the original bed level of the river under any circumstances; i.e., there will be no dredging / desilting beyond the apron level of the regulator. The desiltation project involves only the removal of deposited sediments, i.e., desilting is proposed for the purpose of their maintenance, upkeep and disaster management.

19. The flooding is not caused by the design of the RCB, but by unprecedented sediment deposition. The water level had already risen to that height prior to the construction of the structure. The increase in water level during the flood is associated with sediment deposition and is not related to the RCB structure. This fact directly reinforces the urgent necessity of the proposed desiltation process to restore the cross-sectional area of the river. The construction of regulator cum bridge was carried out as per the original approved plan.

20. It is submitted that Exhibit P5 i.e., the document dated 02.06.2025 is an official communication informing the District Administration about the status of the project sanctioned by the High-Level Empowered Committee on desiltation chaired by the Chief Secretary, Government of Kerala. KIIDC has proceeded with the desiltation work based on the direction and approvals received from the Government.

21. It is submitted that the comments given by the Executive Engineer/1st respondent in Exhibit P6 that "Up on examining the design drawing provided by IDRB and the construction drawing provided by KIIDC, a difference of approximately 2 meters is seen from the solid rock at the bridge's foundation level to the bridge's deck slab. This substantiates the complainant's argument" is against the fact, as explained below.

As per Irrigation Design and Research Board (IDRB) drawing No.21/2016 issued on 22-11-2