In mid-November the Tamil Nadu Water Supply and Drainage Board will start the underground drainage work in Kurichi and Kuniamuthur. Larsen and Tubro Limited will execute the ₹412 crore work on behalf of the board, which, in turn, has taken up the work for the Coimbatore Corporation.

Board officials in the know of developments said with the ground-breaking ceremony completed a couple of days ago, the board would start work after Deepavali, as a portion of testing work remained to be completed in the next three weeks.

During the three-year construction period, the board would lay pipeline for 482.65 km in Kurichi and Kuniamuthur, which it had divided into 13 sewerage zones. The two areas comprised 14 wards of the Coimbatore Corporation.

The pipelines would form part of the collection system of the project, which also included 11 pumping stations, 19 lift stations and five lift manholes. There would be 17,654 manholes as well. The collection system would initially convey 30.53 million litres sewage a day. The sewage would reach the sewage treatment plant in Vellalore and the treated water would flow into River Noyyal.

The board officials said that the 30.53 million litres sewage generation would be until 2020, when the population in the two areas, including floating population, was projected to reach 2.97 lakh. From 2020 to 2035, the sewage generation was estimated to go up to 40.26 million litres a day as the population was projected to touch 3.92 lakh.

The underground drainage project would hold good up to 2050, when the projected population would be 5.17 lakh and sewage generation 53.07 million litres a day.

The second phase of the project would be the construction of the sewage treatment plant in Vellalore, for which the board was in the process of finalising the tender. Once completed, the underground drainage scheme would benefit nearly 69,700 residents.

As for underground drainage coverage for the other nine added areas, the board officials said that they were in the process of completing the survey work, which would take six to 12 months. The survey work would help prepare estimates, based on which the board would float tenders.