CHENNAI: The draft on environmental standards and guidelines for asphalt or bitumen hot mix plants, released by the Central Pollution Control Board (CPCB) earlier this month, has relaxed many of the standards, say environmental activists.
The draft was recently released by CPCB on their website for public feedback. Hot mix plants are mainly used for mixing of stone aggregates with liquid asphalt or bitumen for construction of roads. Preparation of bitumen mix in hot mix plants generates emissions containing particulate matter as well as gaseous pollutants like SO2, NOx, CO, O2, VOCs.
“While it is a good decision for the government to set emission standards for hot mix plants, the parameters are very lenient giving scope for exploitation,” said Kankana Das, an environmentalist. Such plants had for long skipped the eyes of regulation with respect to pollution and emission standards, until recently.
There are no standards for hot mix plants until now, and so CPCB along with National Productivity Council, had conducted a scientific study to establish baseline environmental standards. There are at least 577 hot mix plants across the country according to data CPCB collected from State pollution control boards.
CPCB had studied 15 hot mix plants which were of different type (batch type and drum type) and size to carry out emission monitoring. PM standard for batch mix plant has been set at 150mg/Nm3. However, none of the nine plants studied by the government released such levels.
Similarly, the standard for drum mix has been set at 300mg/Nm3. “Such high levels are dangerous for the environment,” said Kankana.