Sept. 7: The soil conservation department will take up silt-trapping measures at Jyotinagar hill to prevent siltation in the stormwater tunnel at Noonmati.

“The government has realised that any effort to improve the drainage system in the plains will be futile, unless erosion of the hills is checked. Consequently, Dispur has directed the soil conservation department to take steps necessary to prevent erosion of the hills,” a source said.

“In the first phase, we have decided to take up soil and water conservation measures on the Jyotinagar hill, as heavy erosion in the hill has made the stormwater tunnel completely ineffective,” the source said.

The soil conservation department is planning to rope in experts from the Indian Institute of Technology (IIT), Guwahati, and the Geological Survey of India (GSI) to prepare the project in a scientific manner. “We will work on the information provided by the IIT and the GSI on city hills, before preparing the detailed project report,” an official of the soil conservation department said.

The project, which is expected to cost nearly Rs 5 crore, will be funded by the Guwahati Metropolitan Development Authority. It will involve afforestation efforts and construction of concrete structures.

“We will go for massive plantation in the hills, and at the same time concrete structures will also be constructed to trap the silt at the source, so that it does not get deposited in the drains,” the source said. In the next phase, similar measures would also be taken up for other hills in the city.

The mechanical measures will include construction of silt retention dams, spillways and drains with silt pit in the hill.

“These structures will trap the silt and allow only water to flow to the tunnel, considerably reducing the problem of siltation,” he said.

The department is planning to engage the local population in the project. Local groups can be used for collecting the silt from the silt-retaining structures.

“We can form local groups that can collect the silt, which is of a very fine quality, and, therefore, can be used for construction purposes. The groups can earn money by selling the silt,” the official said.

“Checking erosion of the hills will be an integral part of the efforts to improve the drainage system,” he said.

The Noonmati stormwater tunnel was constructed by the National Building Construction Corporation at a cost of Rs 19 crore to divert excess rainwater from East Guwahati to the Brahmaputra.