Two contractors have been fined for silty water discharge and inadequate earth control measures.
Chye Joo Construction and The Builders (Hup Huat) were fined $30,300 and $14,400 respectively this month, PUB said yesterday.
The offences, committed between October and December last year, were uncovered during PUB's regular site inspections and after public feedback.
The national water agency said the contractors have since tightened their earth control measures and silty water is no longer flowing into drains. Such measures are implemented at construction sites to safeguard Singapore's water resources by ensuring silt is not washed from exposed earth into the waterways after rain.
Chye Joo built undersized silty water treatment plants and holding ponds at two worksites in Jalan Gali Batu and Jurong Road, which were up to six times and 22 times undersized respectively. This caused silty water to overflow into the roadside drains and waterways.
Other offences at the Jurong Road worksite included failure to install a perimeter drain to channel surface run-off to a holding pond.
At the Jalan Gali Batu worksite, the silty water contained a concentration of suspended solids that was almost 400 times higher than the permitted limit. The water overflowed to the footpath and roadside drains along Mandai Road.
At another worksite in North Buona Vista Drive, silt built up within a treatment plant, causing it to overload and discharge into a drain.
As for The Builders, it did not build a large enough silty water treatment plant at its Fernvale Street worksite. Cut-off drains were not constructed to contain silty water within its Fernvale Street and Tampines Avenue 5 worksites. There was also no CCTV system to monitor the quality of the water before it was discharged into the drains.
Currently, there are about 1,000 construction sites that involve earthworks. PUB conducts site checks every two weeks or once every two months, depending on the stage of construction work and the size of earthworks. It has taken 100 contractors to task each year in the last three years for failing to comply with earth control measures.
The public can report sightings of silty discharge or pollution in drains and canals to the PUB's 24-hour call centre at 1800-2255-782.