A total of 128 contractors were prosecuted and fined in the first 11 months of the year for carrying out construction works that made alterations to or interfered with the public drainage system, or violated the earth control measures regulations.

Earth control measures are implemented at construction sites to safeguard Singapore's water resources by ensuring that silt is not washed from exposed earth surfaces into the waterways after rain.

Some of the unauthorised alterations made to the drainage system include building structures, pipes and concrete walls in the drains.

Altogether, there were 203 offences committed within that period, PUB said in a statement yesterday.

Among the companies fined were Hwa Seng Builder, Koon Construction & Transport Co and Sato Kogyo (S).

The national water agency said that it uncovered these offences during regular inspections of construction sites and investigations arising from public feedback.

"PUB takes a serious view of construction works that affect our public drainage system, as (they) may cause flash floods and impact water quality in our catchment and waterways," the statement added.

Its director of catchment and waterways Yeo Keng Soon said that silty discharge and unauthorised interference with drains and canals may result in the accumulation of sediment and affect drainage capacity.

So, it is important for the construction industry to maintain high standards in its earth control measures and operations to protect Singapore's public drainage system, he added.

Some of the common offences are having inadequate treatment capacity, inadequate holding pond capacity, and the lack of cut-off drains that separate clean water from silty water.

These lapses would result in silty water overflowing from the construction sites to nearby waterways during heavy rainfall.

Drainage issues: Repeat offenders face punitive measures

Welltech Construction, which was one of the repeat offenders this year, was fined $11,200 for discharging silty water into roadside drains on two occasions, in November last year and January this year.

Last year, it received four convictions for the same offence.

Mr Kenny Chng, project director of the company, told The Straits Times yesterday that it has taken all the necessary precautions to prevent such incidents from re-occurring.

PUB stated that it has conducted joint seminars and sharing sessions on erosion and sediment control with the contractors as well as provided tools - such as drainage and earth control measures checklists - for contractors to use and implement such measures effectively throughout various stages of construction work.

The agency added that contractors who are found guilty of repeat offences will face punitive measures, such as tightened screening of their drainage and earth control measures plans and more frequent inspections of their sites. There could also be heavier penalties imposed for subsequent offences.

PUB penalised 104contractors (involving 141 offences) last year for drainage system violations or providing poor earth control measures at their sites.