AMITA BAVISKAR on Delhi's sluggish sewage: No covering up this mess
Contrary to global efforts at restoring covered streams, the Delhi government’s initiative to concretise and pave nallas is a misstep that will increase drainage problems and destroy vegetation
Like millions of people living in Indian cities, my home is next to a ganda nallah. Only an embankment separates my neighbourhood from the sluggish stream of sewage. On summer evenings, the nallah announces itself with a stench that infiltrates our flats, a bouquet of rotten-egg hydrogen sulphide and methane. Brass lamps and bronze idols are tarnished within a day of being polished. Fridges and air-conditioners need to have their refrigerant gases replaced every year because of leaking pipes. If noxious fumes from the nallah can corrode metal, we wonder what they are doing to the soft tissue of our lungs.
Problems like these are now being addressed by government initiatives to cover up the nallahs. This has already happened in Delhi’s affluent Defence Colony, while work is under way on Kushak Nallah in central-south Delhi and the Shahdara drain in east Delhi. The earthen bed and sides of the nallahs are being concretised and the top paved over. The covered area is to be used for road-widening, parking lots and shops. Many neighbourhood associations support these projects as a solution to a long-standing problem that mars their quality of life and lowers property values. However, instead of improving their environs, covering up nallahs is likely to make their life much worse.
ECOLOGICAL CRISIS
Concretising the channel of a nallah means that it can no longer replenish groundwater. Covering it makes it harder to remove debris and sludge. During the monsoons, constricted flow results in backed up drains and flooding. Reduced oxygenation causes more gaseous emissions, increasing the stink. Manynallahs are lined with trees and shrubs that shelter wildlife. Walking along mynallah once, I was surprised by a raucous party of Grey Hornbills stripping the figs off a peepal tree. But when the vegetation is cleared to enable construction, precious green spaces get decimated. As the environmental NGO, Yamuna Jiye Abhiyan, has argued in a case being heard by the National Green Tribunal, covering nallahs is a decided misstep, one that will take the city further down the path of ecological crisis.
UNDERSTANDING THE LANDSCAPE
How do we then deal with the polluting presence of the nallah next door? This problem requires not kneejerk solutions but an understanding of the natural landscape which the city inhabits. Most nallahswere once seasonal streams that followed the lay of the land, flowing into lakes and rivers. The nallahnear my home was a channel of the Sahibi river, connecting the Najafgarh jheel (lake) in west Delhi to the river Yamuna. It absorbed monsoon overflow, irrigated crops and provided drinking water. So did the Kushak Nallah, a tributary of the Yamuna which was dammed at Satpula in the 14th century by the Tughlaqs. After Independence, as the city grew bigger and denser, public sanitation projects installed underground sewers that debouched into these water bodies. Today, the Najafgarh jheel has vanished and the nallah that flowed from it has become one of Delhi’s three major sewage canals, carrying the combined liquid filth of west and north Delhi to the river Yamuna.
Even in municipal plans, these streams were not originally designated for carrying sewage. They were meant to be storm water drains, bearing runoff from the rains, just as they had done over the centuries. But the signal failure of the authorities to treat the sewage generated by this city of 14 million has led to the nallahs being hijacked for this purpose. A performance audit by the Comptroller and Auditor General earlier this year reported that the Delhi Jal Board collected and treated only 54 per cent of the 680 MGD (million gallons per day) sewage produced by the city. Almost half of the sewage in the city flows untreated through 350 km of nallahs into the Yamuna, turning this once-beautiful river into a black, stinking sheet of sludge.
In theory, Delhi has been building sewage treatment plants (STPs) and now has installed capacity to treat 543 MGD of waste. However, all these plants work below capacity because the Jal Board did not simultaneously build the sewers to carry the waste to the plants. Without these connecting pipes, the STPs are slowly rusting away — a plant in Ghitorni built in 1997 has not worked for a single day, another in Rohini works to 5 per cent capacity — while untreated sewage continues to flow through the nallahs. To this day, Delhi has no comprehensive sewage management plan. In 2008, the Delhi Jal Board launched an ambitious plan to build ‘interceptor sewers’ along the Najafgarh, Shahdara and supplementary nallahs to catch the flow from subsidiary drains and deliver it to STPs but five years and Rs 1,978 crore later, there is little to show for it. Instead, the authorities are steaming ahead with Operation Cover-up.
Tragically, this is being done at a time when cities around the world are waking up to the wisdom of restoring covered streams to life. .. read more:
