Ash being used to build stretch of road here

By Sharmilpal Kaur

ASH from burnt rubbish is being used for the first time to build a road here.

Work has already begun on the road-widening project near Pandan Reservoir in the West.

It will see about 1,200 tonnes of ash from the Senoko incineration plant being used in a 150-m stretch of Jalan Buroh, which is being widened by two lanes.

The recycled ash will be used for the base, which will then be covered with asphalt.

The rest of Jalan Buroh, which is more than 8.5 km long, will be widened using normal materials like granite in the base. The road will be opened in March.

Environment Minister Lim Swee Say, who was at the work site yesterday, told reporters that the trial road would be monitored closely over the next six months to make sure it is safe.

Groundwater samples will be taken regularly to monitor the environmental impact of the ash.

Some international reports on the use of ash in road construction say it could harm the environment. But other studies say that if properly managed, it is safe enough. When asked about this issue, Mr Lim said some countries blended the bottom ash with fly ash, which could release potentially cancer-causing dioxins.

The bulk of the incinerated waste is known as bottom ash, normally used in road construction. The rest is known as fly ash, which can be toxic as it contains more heavy metals and has a higher lime content.

He said: 'In our case, we adopt the best practices. Firstly, we do not blend the bottom ash with fly ash. What you are seeing here is purely bottom ash.'

He said the bottom ash was carefully processed and screened, with steps having been taken to ensure the ash is not harmful.

For example, large items and ferrous metals like lead, which can be toxic, are removed before the rubbish is incinerated. After burning, the ash is left to age for eight weeks, to stabilise it.

Experts from the Environment Ministry (ENV), Public Utilities Board, Land Transport Authority and Hanson Pacific, a firm experienced in processing ash for use in European roads, are part of the team formed to work on the road project, the second to be funded by ENV's $20-million innovation fund.

So far, about $50,000 has been spent on processing the ash.

On whether using the ash will mean cheaper roads, Mr Lim said although there were some savings, the real gain lay in reducing the amount of ash sent to landfills.

Singapore throws 7,600 tonnes of rubbish a day, most of which is incinerated and sent to the landfill at Pulau Semakau. The 1,600 tonnes of bottom ash produced each day make up half of the trash disposed there.

Mr Lim said: 'The key issue is not about cost, but about sustainability, because where are we going to find a Pulau Semakau every 30 years?'