On The Drain Front… A Brief History of the City’s Sewerage & Drainage System (1700s ~ 1950s)

It appears to have taken 16 years to complete the main sewers of Clark’s Scheme.  By 1875 nearly 38 miles of brick and 37 miles of stoneware pipe sewers were constructed. The pumping plant at Palmer’s Bridge comprised two 30 and one 45 PHP vertical centrifugal steam pumps and two huge silt-pits provided with penstocks. These penstocks also shut off the flow of the sewers from the channel to the Beliaghata Canal. During the rainy season they were opened so that the sewers could discharge fully into the canal providing a great relief from storm-water overflows between Upper Circular Road sewer and the Circular Canal. The drainage works of the Southern Division were finally completed in 1878 and those of the Northern Division between 1885-86.

Clark’s original scheme was not complete when the Corporation was compelled to undertake additional works to prevent the discharge of storm-water into the canal. Calcutta’s Canals (Circular, New Cut, Bhangur Khal, Kestopur and Tolly’s Nullah) though excavated principally for navigation, helped in draining the City to a considerable extent by carrying storm-water until the end of the nineteenth century. In 1880, however, the Government Irrigation authorities objected to the storm-water being discharged into the canal, although there could be no doubt that the canal had intercepted the natural surface drainage channels of the city.  The Government in 1881-82 stopped the discharge of storm water into the Circular Canal. The city drainage was thus disoriented and the escapes into the Circular Canal had to be checked by a long intercepting sewer that diverted the drainage to the existing Town Head Cut.

After a long controversy with the Government the Corporation reluctantly agreed in 1881 to: (i) construct an intercepting sewer to increase the dimension on the outfall channel (the open cut) to a capacity of about 90,000 cubic feet per minute; (ii) to construct tide-gates of four openings 10 feet wide at Makalpotta; and, (iii) to divert the storm-water of the northern area of the city to the Beliaghata Canal below Dhapa. 

This intercepting sewer ran parallel with and close to the canal from Habsi Bagan Road to Palmer’s bridge, where it joined the outfall channel. But unfortunately it was constructed, like most of the city sewers, with the smaller sections joining the larger invert to invert and the levels at which it was constructed did not allow it to take the required discharges from the storm overflows without causing the water to stagnate in the low-lying areas of the city.  There were 37 miles of main or brick sewers and 147 miles of pipe sewers in Calcutta by 1890.

The Added and Fringe Areas, covering 8188 acres, were incorporated in the town of Calcutta in 1889. The development of these areas was entrusted to a committee, called the Suburban Improvement Committee. For the purpose of drainage the new areas fell naturally into 3 blocks:

                       I.         The portion west and south of Tolly’s Nullah, including the new docks. This drained towards the south and southwest;

                     II.         The area east of Tolly’s Nullah, including Ballygunge and Entally. This drained towards the Bidyadhari; and

                   III.         The area lying between the Circular canal, Circular Road and the Eastern Bengal State Railway lines, devoid of all drainage except in so far as the drains of Calcutta provided outlets

Under the Suburban Sewerage Scheme executed between 1891 and 1906, 12.5 square miles (32 sqkms) in the newer southern areas of the city were covered. A new pumping station was constructed at Ballygunge and the capacity of the Palmer’s Bridge station augmented. The drainage system could, therefore, dispose off storm-water from one-fourth of an inch rainfall per hour plus 40 gallons of sewage per inhabitant per day. This ‘combined drainage’ flow was brought through the underground sewerage network to Palmer’s Bridge and Ballygunge pumping stations. It was then pumped into high-level sewers meeting at a place called “Topsia A”. From here, the discharge flowed by gravity directly into Raja Khal, a creek of the tidal river Bidyadhari.

Burdened with the outfall of the entire city’s drainage system, the Bidyadhari began to show signs of rapid deterioration. In 1928, the Government declared it to be a dead river. The city was thence almost trapped in a drainage deadlock. At this juncture, Dr Birendranth Dey (1891-1963) came up with a new scheme for both the outfall and the internal drainage system. The Outfall Scheme comprised of:

                       I.         Lined dry-weather flow channel from Topsia A to the river Kultigong at Ghusighata, discharging into the river through a sluice at the outfall

                     II.         Storm-water flow channel (the Suburban Head Cut) from Ballygunge drainage pumping station to the Kultigong at Ghusighata, discharging through the above mentioned sluice

                   III.         Storm-water flow channel (the Town Head Cut) direct from Palmer’s Bridge Pumping Station, joining the dry-weather flow channel near Topsia A at Bantala, where provision was made for two sedimentation tanks for primary treatment of the dry-weather flow

                   IV.         Storm-water flow channel from the Dhapa lock pumping station, joining the channel with the above mentioned one at Makalpota

     This Scheme was commissioned only in 1943. It has since undergone major modifications and expansion to meet the rapid growth of the city’s area and population.

 

concluded