REFUSE chutes at 20 HDB blocks all over the island will periodically squirt water on rubbish in a one-year pilot project to prevent it from catching fire.
The idea is to wet the refuse collected within the chutes by discharging water at pre-determined timings so that it will not be easily ignited by, for example, a cigarette butt thrown into the chute.
The Singapore Civil Defence Force (SCDF), National Fire and Civil Emergency Preparedness Council, and the HDB will install the Timer-based Water Release System at the 20 blocks of flats islandwide - 10 built before 1990 and 10 newer ones - next year.
The SCDF declined to give details on how often the water will be discharged, saying that this will be calibrated during the trial to ensure prudent use of water.
Rubbish chute fire is the most common type of residential fire and has been occurring more frequently. In the first half of this year, 819 fires occurred in rubbish chutes and bins, compared to 680 the year before.
It formed more than half of the 1,493 fires that happened in residential premises, SCDF statistics showed.
"The installation of the system would serve as a pre-emptive measure to reduce the occurrence of such refuse chute fires," said a spokesman for the SCDF.
"While they generally do not pose a major fire risk, the resulting smoke inconveniences the residents.
"It also drains the SCDF fire-fighting resources in attending to more than a thousand of such minor fire incidents annually," he said.
In all HDB blocks, the flushing system used to clean the chute can double up as a water-sprinkler if a fire occurs. But this can be activated only by rubbish collection workers at the ground floor.
Each HDB block constructed from 1990 has a central refuse chute which ends in a bin centre.
The bin centre is fitted with heat detectors that can trigger the flushing system, but these sensors detect only fire in the bin centre, and not directly within the chute.
Previously, the SCDF, the council and the HDB carried out two trials to address the problem of chute fires, but both methods that were tested had drawbacks.
In 2006, automatic sprinklers were installed within some rubbish chutes in some older blocks in Jurong West, but installation costs were high and the moist environment within the chutes corroded the heat detectors over time, rendering them ineffective.
In 2011, buttons to activate the chute flushing system were installed in the common areas of some blocks in Tanjong Pagar GRC, so residents could press them to release water down the chute if a fire broke out.
However, this led to a number of false alarms and the buttons were pressed when there were no rubbish chute fires, resulting in water wastage, said the SCDF.
It added that more rubbish chute fires tend to occur during the festive season - about half of the 819 cases from the first half of this year happened in January and February due to indiscriminate disposal of lighted materials such as sparklers, charcoal and incense materials.
The SCDF has been visiting clusters of flats that show high incidences of rubbish chute fires to remind residents to refrain from throwing lighted cigarettes, charcoal with embers or flammable substances such as oil and paint into the rubbish chutes.
Retiree David Kwok, 63, said: "The new system is good because it is proactive and doesn't wait for fires to start or smoke to appear before being activated.
But the downside is that it may waste water, and rubbish that is wet can be heavy for the workers when they clear it."
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