‘Lake lacks surplus flood disposal system except for one sluice-controlled gate valve’

Mysore/Mysuru: The technical team from Cauvery Neeravari Nigam Limited (CNNL) that visited the Kukkarahalli Lake and carried out an inspection last Monday has submitted its interim report.

Former Member of Karnataka Tank Conservation and Development Authority Dr. K.M. Jayaramaiah; Executive Engineer of Engineering Wing of University of Mysore Prathap and Assistant Executive Engineer Shivalingaprasad had requested the CNNL team to inspect the Lake and suggest remedial safety measures in the wake of water seepage from the Lake bund and also the damage caused due to water overflow.

H.K. Sampath Kumar, Technical Consultant (Designs) of CNNL noted in his report that the Lake does not have any surplus flood disposal arrangement apart from a sluice controlled by gate valve which cannot efficiently dispose of the flood during an emergency.

Following concerns that the Lake bund or the embankment could collapse due to heavy rain and the residential and commercial areas could face catastrophic consequences, the team has suggested construction of a ‘rock toe’ in the downstream of the Lake to reduce dampness due to seepage in the downstream embankment as an immediate safety measure.

Gated head regulator

Further, it has been recommended to construct a gated head regulator on the left flank of the bund for flood disposal as a permanent measure. During inspection it was noted that there is slight wetness on the lower portion of the bund downstream at two to three locations.

At present, no cracks or settlement is observed and clear water is emerging out of the surface which is not alarming. Soil samples have been collected from the downstream slope of the bund for investigation by the engineers from the Karnataka Engineering Research Station (KERS) and a report is awaited, the CNNL interim report noted.

The CNNL team has recommended that the key plan or the schematic map indicating all the inlet point location, tank bund and downstream valley must be prepared. “Further, the surplus water has to be discharged downstream of Lingambudhi Lake located on the downstream of Kukkarahalli Lake and hence dimensional sketch of surveyed downstream valley details has to be prepared,” the report said.

Soil test report

Safe bearing capacity (SBC) test report and soil classification report at the location where the gated head regulator is proposed has to be prepared. Tests should also be conducted on soil parameters such as moisture content, permeability and specific gravity of the existing Lake bund to assess the safety and stability of the existing bund, the report has recommended.

Dr. K.M. Jayaramaiah told Star of Mysore that the CNNL and the KERS can submit a joint report on the remedial measures to be taken to save the Lake instead of submitting two reports. “The CNNL and KERS authorities can brainstorm and arrive at a common report so that a definite conclusion can be reached and immediate measures taken,” he said.