Works to provide underground drainage to 49 out of the 72 wards in the city were under progress and the aim of the Corporation was to complete these within the stipulated time of two-and-half years, said Mayor R. Venkatachalam.
The works began towards the end of 2009, after orders for these were issued on September 2 that year.
Launching the works in Ward 63 on Sunday, the Mayor said 2,200 testing pits had been dug and lines laid over 32 km in Wards 12 and 13 and 54 to 60.
On the work launched on Sunday, he said the drainage in the ward would help in providing sewer connections to 8,000 houses.
A Chennai-based private firm was implementing the scheme to provide a large part of the city with underground sewers, including more than 500 layouts that were regularised after a long wait.
The scheme was being implemented at Rs.377 crore under the Jawaharlal Nehru National Urban Renewal Mission, with 50 per cent of the project cost being met by the Central Government in the form of a grant.
The State Government provided a grant of 20 per cent.