Saturday, November 07, 2009

Work to clean up storm drains can save lakes, tackle water shortage

Work to clean up storm drains can save lakes, tackle water shortage

BWSSB's project, to be completed in 2012, will prevent sewage water from flowing into storm water drains. Only treated water will be let into lakes while storm water will be reused for non-potable purposes to address water shortage and harness rain water. Senthalir S reports

Senthalir S



The city's dying water bodies are going to regain their health as a civic project is under way to treat storm water and prevent sewage from contaminating it.
Right now, any waste, including sewerage, that enters a storm water system is discharged untreated into the water bodies we use for swimming, fishing and drinking. But a new project being implemented by the Bangalore Water Supply and Sewerage Board (BWSSB) envisages separating sewage water from rain water. While the sewage water will be recycled after treatment, the storm water will be used for non-potable purposes.
The new project, billed to address both the acute water shortage facing the city and harnessing rain water going down the drains, proposes to delink sewerage lines from storm water drains. While the water in sewerage lines will be directed to the treatment plants to render it fit for recycling, the rain water that enters the storm water drains will be diverted for non-potable purposes.
"Tertiary treatment plants will be used to treat sewage water and the treated water will be either reused or allowed to flow into the lakes. At least 20% of the treated water will be used for non-potable purposes and the rest will be released into the lakes. The storm water drains will collect rainwater and this will be utilised for non-potable purposes," a senior BWSSB official said.
Giving out the project details, the official said that at present, most of the sewerage lines are linked to storm water drains. This not only pollutes the rain water but also contaminates ground water and lakes.
According to the project, to be taken up under the Jawaharlal Nehru National Urban Renewal Mission, sewerage lines will be changed and placed beside the storm water drain; they will run parallel but will not be linked, thereby preventing the possibility of sewage water entering storm water drains.
Another official said that due to increase in population, the load on sewerage lines has doubled. Thus there is a need to replace all old lines and repair the ones that are blocked.
Under the Environment Action Plan, the project has been divided into Phases A, B and C. "All the four valleys -- Vrishabhavathi, Hebbal, Chellaghatta and Koramangala -- will be covered under the three phases. We are aiming at making the storm water drains free of sewage water by 2012," said the official.
In the first phase, the Hebbal valley project will be undertaken on a pilot basis. The project has been sanctioned for Rs35 crore. Sewerage lines of 450mm thickness and above will be replaced. About 6km of sewerage lines will be replaced in the pilot project. "The project has been formally approved. Tenders have been issued and the scheme will be completed in a year,"
he said.
The BWSSB plans to take up the project on piecemeal basis. After Hebbal valley, the other three valleys will be cleared of sewage water.
"Work on these three valleys will be taken up in two phases. Work of immediate nature like repair works will be done immediately. The estimated cost for this is Rs330 crore," the official said.
However, experts feel that there is a need for focused work on cleaning up the storm drains.
"Before a new building comes up, the water board should be on the vigil. They should correctly place the sewer lines so water does not get into storm water drains," said Capt Raja Rao, chairman of Environment and Power Technologies Private Limited.
Only if such steps are taken will the city be free of water pollution. For better functioning, the water board should be spilt into two entities, one focusing on water supply, and the other on sanitation. This will increase the accountability of the board, he said.

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