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Wednesday, February 6, 2008

Delhi's Interceptor Sewage Project


The Delhi government plans to add another 50 kilometers of sewers at a cost of Rs. 1950 crore along the three major drains to intercept sewage from 150 minor drains, from where the sewage will be passed on to pumping stations and finally transported to sewage treatment plants for treatment.

But according to recent studies of CSE(Centre For Science and Environment) and there article its just a wastage of money.And according to CSE, the river will continue to remain dead, despite the massive amounts of money being spent.So here i just wanted to briefly focus on there article, so that we must come to know why they think such about this big budget project.

According to CSE & there article: More than Rs. 1500 crore has already been spent in trying to clean the Yamunas 22-km stretch through Delhi. Money aside, the interceptor plan is full of gaps. The project is not based on any authentic estimates of the amount of sewage that is generated in the city. It completely overlooks similar, expensive failures elsewhere as in Agra and Varanasi. Even if forcefully pushed through, the river will need millions of litres of freshwater to dilute the intercepted and treated sewage; water that is just not available.

PROJECT's DETAIL:
Government wanted to tap drains carrying sewage from colonies not connected to the city sewers. Interceptor sewers to be used for tapping is seen by the government as a temporary solution to the problem of untreated water reaching the Yamuna.The government plans to lay sewers throughout the city in the long run.

The project is a toned down version of a Rs 3,150-crore proposal first mooted by the Delhi Jal Board in 2006. It involves laying 50 km of interceptors, 2-3 metres in diameter, to intercept 150 small drains discharging into three major drains in the capital—Najafgarh, Supplementary and Shahadra. The three drains contribute 70 per cent of the discharge of 3,600 million litres a day (MLD) of sewage into the Yamuna.

Another 13 drains will be tapped into sewers under rehabilitation. Four drains including one near the Sarita Vihar bridge carrying about 690 MLD finds no mention in the plan, which has been cleared without undertaking surveys directed by the supreme court.

The intercepted waste will be taken to a pumping station and then to a sewage treatment plant (STP). At places, the route is very circuitous. For example, sewage from a drain near the Yamuna Vihar S T P would be sent to a distant pumping station, when pumping directly to the plant would have been prudent since, each kilometre of sewer costs almost Rs 20 crore. Also in monsoons the wastewater will bypass the interceptors into the Yamuna.

Delhi’s STPs can reduce sewage’s biological oxygen demand to only 20mg/l (if they work); 3 mg/l will make the river fit for bathing. So the treated water will need more than six times dilution. But where’s the water? The Yamuna lacks freshwater almost nine months a year.

WASTAGE OF MONEY:
  • Rs 1,950 crore for interceptors is in addition to Rs 387 crore under the Yamuna Action Plan II and Rs 1,500 crore spent on Yamuna cleaning in Delhi. But interceptors have failed in Agra, Varanasi and other places.
  • They will not work in Delhi as well because even if all the city’s sewage (3,600 M L D) is intercepted and treated the river would require 24,000 MLD of freshwater for diluting it to make it fit for bathing, at a conservative estimate.
  • Sewage generated in Delhi is increasing. Water supply management is no solution. More freshwater used means more sewage and more money for treatment. Manage demand.
  • Augment and optimize current STPs. Treatment at source reduces pumping costs. At places drains can be developed into treatment units. Treat residual wastes at the mouth of the river.
  • Re-use effluents and ensure treated effluent is not mixed with untreated effluent before it flows to the river. Have policies to promote safe re-use so that the river has freshwater.

Source: www.cseindia.org
Compiled By: Saurav Chakraborty

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1 comment:

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