MUMBAI: The downpour has poured water over the civic body's claims of cold mixes being the solution to potholed roads.

Besides leaving some stretches pockmarked afresh, the heavy rain also washed away the cold mix that was used to fill the potholes this year. According to the BMC data, of the 17,243 potholes reported this season, 16,035 were attended to, but a source said at least 20% of the filled-in craters were re-exposed following the rain. Even engineers inspecting the roads to check the efficacy of cold mix-the technology approved and being used for road repair-have admitted that the mixture has come off at several spots.

"There are a few instances of the cold mix being washed away in the rain. The potholes are under defect liability and if the craters are re-exposed, the contractor will have to fill them again, without billing for it more than once," said a senior civic official from the roads department. Tilak Bridge, road 32 in Matunga, the road outside CST, the stretch near Elphinstone station, the road near Bimbisar Nagar in Goregaon are examples of potholes coming up on the same spots.

The shoddy job and the wastage of money has raised the hackles of corporators. "The money spent on filling potholes is wasted. The civic staff do not take care to supervise the execution of the project by contractors and even substandard work is being tolerated," said BJP corporator Vinod Shelar.

This year, the civic body rejected the hot mix technology and zeroed in on cold mix for road repair. The three methods, Wonder Patch, Patch Master and Hindustan Colaco, are supposed to fill craters quickly and effectively. For the project, the civic body allotted Rs 40 crore. The advantages of the cold-mix technology are that the work can be finished quickly and efficiently and the material is supposed to have more power to sustain wear and tear than other material used. After repair, a road can be opened to traffic earlier than when asphalt is used.

Earlier, the civic body had filling potholes using either hot asphalt, or a hot sprayed bitumen with stone chips mixed into the hot mix.