Plan based on wrong es­ti­mates

The pro­posed Sew­er­age Master Plan 2031 that prom­ises to end Delhi's drainage trou­bles un­der­es­ti­mates the waste­water vol­ume of the city


Sew­er­age Master Plan 2031 has been drafted on the grand prom­ise of end­ing Delhi's drainage woes, but with false as­sump­tions

Dno­to­ri­ous for its over­flow-ELHI IS ing drains and poor san­i­ta­tion. The sit­u­a­tion is so bad that just half of the city’s pop­u­la­tion has sew­er­age con­nec­tion. Me­dia re­ports show that cases of wa­ter-borne dis­eases like cholera are re­ported more from ar­eas lack­ing sew­er­age sys­tems such as Ro­hini and Shah­dara. This un­der­scores the need for con­nect­ing ev­ery house­hold with proper sew­er­age sys­tem—a task that of­fi­cials of Delhi Jal Board (djb), the city’s wa­ter util­ity, say will be achieved soon. “It is just a ques­tion of time and the whole of Delhi will be con­nected to sew­ers,” says Rad­hey Shyam Tyagi, mem­ber (wa­ter), djb.

The rea­son for djb’s op­ti­mism is the re­cently drafted pro­posal of Sew­er­age Master Plan for Delhi 2031.The new plan in­volves lay­ing 9,807 km of sewer net­works and pro­poses 75 new sewage treat­ment plants (stps) at 38 lo­ca­tions. It also plans to in­crease the city’s to­tal waste­water treat­ment ca­pac­ity from 2,700 mil­lion litres of wa­ter per day (mld) to 4,383 mld.

But a closer look shows that the plan, though am­bi­tious, has failed to ad­dress the ba­sic is­sues that have crip­pled the city’s sew­er­age sys­tem. The djb’s draft pro­posal, pre­pared in col­lab­o­ra­tion with gov­ern­ment un­der­tak­ing wapcos and pri­vate con­sult­ing firm aecom, was made pub­lic on Septem­ber 10 for com­ments and sug­ges­tions.

Flawed as­sump­tions

The pro­posal has been drafted with the as­sump­tion that merely in­creas­ing the num­ber of stps can solve Delhi’s san­i­ta­tion prob­lems. But past ex­pe­ri­ence shows it will not work.At present, the city has 34 stps at 21 lo­ca­tions. Th­ese plants work at only 57 per cent of their ca­pac­ity.The draft is silent on how to make the ex­ist­ing stps op­er­ate at full ca­pac­ity. It also con­ve­niently as­sumes that the 75 pro­posed stps will op­er­ate at their full ca­pac­ity.

The other prob­lem is that while cal­cu­lat­ing the amount of waste­water that will be gen­er­ated be­tween 2011 and 2031, djb has ig­nored the ground­wa­ter ex­trac­tion through pri­vate bore wells.The wa­ter util­ity has no data on how much ground­wa­ter is be­ing ex­tracted in the city. This might sub­stan­tially in­crease the city’s waste­water as the gen­eral thumb-rule is that 80 per cent of wa­ter used gets con­verted into waste­water.

One of the prob­lems with the ex­ist­ing sew­er­age sys­tem is that treated wa­ter from stps get mixed with waste­water be­fore it reaches the Ya­muna. This hap­pens be­cause the drains that are sup­posed to carry the treated wa­ter get pol­luted with waste­water that is re­leased from un­sew­ered colonies near the drains. Un­der the master plan, djb claims

this mix­ing of treated sewage and waste­water will not hap­pen be­cause the en­tire city will have sew­er­age con­nec­tion. But since it is un­der­es­ti­mat­ing the ac­tual waste­water out­put of the city by not in­clud­ing the dis­charge on ac­count of ground­wa­ter ex­trac­tion, the prob­lem of waste­water find­ing its way into drains will re­main (see ‘A fu­tile ex­er­cise’).

“If th­ese as­sump­tions fail, it would be a great blow to the plan,” says Manoj Mishra of Delhi-based non-profit Ya­muna Jiye Ab­hiyan. Mishra says the plan is also silent on the de­sign im­prove­ments that are re­quired in the ex­ist­ing stps.The present stps need to be up­graded to be able to treat waste­water with high bio­chem­i­cal oxy­gen de­mand and to­tal sus­pended solids. Since the new and old sys­tems would be in­te­grated, only de­sign­ing new ones to han­dle the im­pu­ri­ties would not serve the pur­pose. Tyagi says the up­com­ing Ya­muna Ac­tion Plan (yap)-III will look at the de­sign upgra­da­tion re­quired in the ex­ist­ing stps. yap-I was launched by the Union gov­ern­ment in 1993 to im­prove the wa­ter qual­ity of the Ya­muna. It was fol­lowed by yap-II. But the two projects have failed to im­prove the qual­ity of the river. In fact, Cen­tral Pol­lu­tion Con­trol Board data shows that de­spite the two yaps, Ya­muna’s pol­lu­tion lev­els have wors­ened over the years.

The other ma­jor prob­lem is that many of the ex­ist­ing stps are lo­cated in ar­eas where not much sewage is gen­er­ated. This has hap­pened be­cause find­ing land for stps in an al­ready crowded city is dif­fi­cult, ac­cord­ing to the draft of the master plan. Find­ing land for the 75 new stps will be a big chal­lenge. Deepak Lakhan­pal, deputy chief en­gi­neer of wapcos, says the plan is ef­fec­tive but needs to be im­ple­mented soon. Since djb is plan­ning to get it im­ple­mented in phases, the gap be­tween phases might in­crease the pop­u­la­tion and waste­water gen­er­a­tion in many ar­eas. “This would make the cal­cu­la­tions go hay­wire,” ad­mits Lakhan­pal.

An op­ti­mistic Tyagi says djb will soon hold a work­shop and fi­nalise the plan, which he claims “will im­prove the qual­ity of life”. The Sew­er­age Master Plan for Delhi 2031 is no doubt am­bi­tious, just like Delhi’s ear­lier at­tempts to clean the Ya­muna. The trou­ble is that this too will fail if djb does not get its fo­cus right.


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