Cyclone and Storm Surge - Iczmpwb.org

3.7
3.4 Drainage Scheme of William Clarke
The first major modifications in the drainage system came in the wake of the Sepoy Mutiny, 1857,
when the responsibility of governance changed hands from the East India Company to the Imperial
throne of England by the Proclamation of Queen Victoria. Meanwhile, the Calcutta Municipality had
been established earlier in 1841 and the scheme for the "Water Carriage System" of the city as
prepared by its first engineer, Mr. William Clarke, was sanctioned on April 20, 1859 and cost an
estimated Rs. 34 lakh. The plans under the proposal were executed between 1860 and 1875. known
in civic parlance as the "Town System" as separate from the "Suburban System" which came later,
was combined sewerage cum drainage system, designed to drain an average rainfall of 6 mm (1/4
inch) per hour with cent percent run-off in addition to 182 litres (40 gallons) of domestic sewage per
capita per day. The underground drainage system comprised various sized conducts from 6.1 m (20
ft.) dia. brick outfall sewers to 15 cm (6 inches) dia. pipe drains. The main sewers, draining 4600
acres (around 18.50 sq. km.) of land and running generally from west to east, were connected on the
summit points to the penstocks opening into the Hooghly river to flush the sewers by the river water.
The bottom points at the east extreme were connected to the intercepting sewer laid along the
Circular Road. The underground drains measured around 2.44m high and 1.83m wide, with an eggshaped
cross section. Sewage was lifted at the Palmer's Bridge pumping station to a high level
sewer leading to Tangra and finally flowing into the Raja khal, an offshoot of the Bidhyadhari river,
which was a thriving tidal channel at the time. Three storm-water overflows were provided running
into the Circular canal. But the canal authorities resented this undesirable inflow into the canal and
finally further intercepting sewers were laid under the Canal West Road to intercept all these
overflows and to lead them on to the Palmer's Bridge pumping station. Later, in 1896, the scheme
was modified to include an additional drainage area, thus resulting in a total area of 19.2 sq. km.
Most of the drainage network as established under the Clarke’s scheme is still giving service to the
city, though the outfall into the river Bidhyadhari had to be changed later due to its high siltation. This
aspect is discussed in section 2.4.7.
3.5. Drainage scheme of Hughes and Kimber
Hemmed in by the Hooghly river on the west and the Salt lakes on the east, the city grew largely in
the south in preference to the north, where adequate land was difficult to come by. To meet the
drainage requirement of these freshly built up areas in the south, the Ballyganj pumping station was
proposed. The Palmer's Bridge pumping station also needed augmentation in capacity to dispose a