Stone crushers forced to adopt dust suppression system

An edited version of this article was first published in The Express Tribune on Apr 8, 2013.

Islamabad – A government environmental watchdog’s efforts to curb air quality degradation due to stone crushing at the Margalla Hills are bearing some fruit.

At least one of the stone crushers that operate in Taxila has installed a dust suppression system and another is using water to settle the dust generated during the crushing process.

Around 100 stone crushers operate on the western end of the Margalla Hills National Park and the Rawalpindi District Environment Office (DEO) has been on a crusade lately to limit their activity.

Although stone crushing is a major threat to the natural habitat and forestation in the Margalla Hills, the DEO is focusing on the air pollution aspect of stone crushing.

The dust clouds generated by grinding boulders and rocks into fine gravel and by emissions from the vehicles used for gravel transportation contribute to particulate matter in the surrounding air.

The Express Tribune had previously reported that studies conducted by the DEO and the Pakistan Environment Protection Agency (Pak-EPA) estimate particulate emissions from stone crushing to be 33 to 40 times more than national environment quality standards.

The DEO suggests stone crushers adopt dust suppression techniques such as wet scrubbers and sprinklers. Now, Khawaja Stone Crusher is perhaps the first crushing unit to experiment with such a system.

The dust suppression technology used by Khawaja Stone is not advanced or complicated. It uses tarps to cover the crushing plants where rocks are broken down into fine pebbles. Water, pumped from a nearby tank and supplied using regular garden hoses, is sprayed on the rocks as they are being disintegrated using shower heads.

“The dust is generated when a rock, usually six inches in diameter, is broken to make gravel,” Muhammad Mansha, manager at Khawaja Stone Crusher, said.

Mansha claimed the dust has been reduced by around 95 per cent.

Shaukat Hayat, the Rawalpindi DEO secretary, said the effectiveness of dust suppression is being tested by the DEO. But Hayat admits that this is a start for the crushers who previously did not even acknowledge their crushing plants were a source of air pollution.

Another company, Afridi Stone Crusher, is using water through regular pipes to settle the dust.

“There used to be so much dust it was impossible to sit here,” said owner Zia Afridi, sitting at his office near the crushing site. “Now, the situation is much better.”

This change of attitude among the stone crushers might be because of action taken by the Punjab environmental tribunal.

Most of the new stone crushers in the area, working on lease permits issued by the Punjab Mines and Minerals department, never conducted initial environmental examinations to get a No Objection Certificate (NOC) from the provincial Environment Protection Agency (EPA) before they started work. The NOC is a legal requirement under the Pakistan Environmental Protection Act 1997, which was adopted by Punjab in 2012 post-devolution.

In February, the tribunal fined six stone crushers Rs30,000 for operating without NOCs, on th basis of notices served by the DEO. The tribunal also ordered them to be fined Rs1,500 per day if they do not come into compliance within two months. The two-month period will be over when the tribunal conducts its proceedings on April 11 and 12 in Rawalpindi.

Water is the main cost associated with the dust suppression mechanisms. Some of the stone crushing units, such as Khawaja and Afridi, had already invested in water through boring to provide drinking water for their staff.

“Excluding water, the other equipment for dust suppression costs less than Rs100,000,” Mansha said. “But water boring alone costs nearly Rs200,000.”

Crushing units without water will have to buy water tankers if they install a suppression system. The daily charges for the water tankers might be high, but perhaps stone crushers would consider it if there is no lapse in the collection of the Rs1,500 daily fine precedent set by the tribunal.

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