The city of Chandigarh has a well planned underground network of pipes for the disposal of sewerage generated in the city. It is obligatory for every residential/ non residential.
The sewerage system of the city has been designed by taking into account the natural slope of the city, which is from north to south. The sewage of The city flows under gravity in various pipes of different diameter ranging from 6” to 18” S.W.Pipes and 24”x36” to 66” dia circular Brick sewer. The total length of the sewer lines in the city is 890 km. The sewage is carried to a site in the south of the city where a plant has been constructed for its treatment and the treated sewage is than disposed off in an open Nallah. There are few pockets in the city which are at lower level and thus the sewage of these pockets cannot be discharged under gravity into the sewerage system of The city. The sewage of these pockets is pumped into the sewerage system and thereafter it flows under gravity to the Sewage Treatment Plant.
The Sewage Treatment Plant, spread over an area of 48 acres, is located at Sector 66 of S.A.S. Nagar in Punjab Territory which is at a distance of about 4 km from the nearest planned Sector 47. The present capacity of the Sewage Treatment Plant is 30 MGD although about 48 mgd sewage is received at the Sewage Treatment Plant. The sewage received at S.T.P. is subjected to primary, secondary and tertiary treatment. Out of the 48 mgd sewage received at the Sewage Treatment Plant, 35 mgd is treated upto secondary level and out of this 10 mgd is further treated upto tertiary level. The tertiary treated sewage is recycled back to the city for irrigation of open spaces/ gardens. The Secondary treated sewage is disposed off in an open Nallah. There were frequent break downs in the supply of tertiary treated water due to leakages in the line. Zero velocity valves have been provided in the line for avoiding break downs.
The increase in the population and increasing water supply has resulted in increased sewage flow. This has necessitated augmentation of sewage treatment plant. For the treatment of sewage and the disposal of treated sewage into the open choe, the construction work of 5 mgd sewage treatment plant at Raipur Kalan has been taken into hand. This is likely to be commissioned by the end of next year. Efforts are also being made to enhance the existing capacity of the Sewage Treatment Plant at Diggian from 30 mgd to 50 mgd. Further, a study is being conducted wherein the big campuses like Punjab University, PGI, Govt. Hospital Sector 32 etc. will be required to install captive treatment plants in their campuses. The sewage generated in these campuses/ institutions will be treated at these captive plants and the treated sewage will be used for the irrigation of open spaces in these institutions. This will not only help in reducing the burden on the sewerage network of the city but also help in reducing the cost of taking the sewage from the residential and commercial premises to the S.T.P. and thereafter recycling it back to the city after treatment for irrigation of open spaces/ parks.
There are many unauthorized colonies in the city. To check the residents of these colonies from defecating in the open areas, the community toilets in the form of sulabh sauchalyas and mobile toilet vans have been provided in these colonies. The Corporation has provided 47 mobile toilet vans and constructed 20 sulabh sauchalyas in the colonies. In order to mechanise the system of cleaning of sewerage system, sewer cleaning machines have been procured by the Corporation.