The Water Treatment Plant (capacity 4400 m3 per hour) constructed by Calcutta Metropolitan Water and Sanitation Authority is located at Serampore on the western bank of the River Hooghly, 20 Km north of Calcutta. The Plant aims at serving a population of ten lakhs in seven municipal areas in Calcutta Metropolitan District. The municipalities are Baidyabati, Bhadreswar, Champdani, Konnagar, Rishra, Serampore and Uttarpara-Kotrang all within the district of Hooghly.
Raw water is first drawn by pumps from the river Hooghly through a 60 metre long Intake Jetty, located 700 metres from the Plant. The Raw Water Pumping Station presently has 3 pumps, each capable of drawing and delivering 2250 m3 of river water per hour. The station has space for providing 3 additional pumps in future. Water is conveyed to the Treatment Plant through a 1100 mm dia pressure pipeline.
In the treatment plant, raw water is first treated with Alum and Chlorine churned in a Flash Mixer (4.2m dia), flocculated and sedimenied in two Clariflocculators (47.5m dia with a detention time of 3.5 hrs. each). The clarified water, with an output turbidity of less than 15 p.p.m. is passed through 10 Rapid Gravity Filler beds (filtering capacity 440 m3 per hour per bed) in the filtration plant. The filtered water after disinfection by chlorinators flows to the Clear Water Reservoir (Capacity 9 million litres). The filtered and disinfected water is pumped into the 27 Km long Primary Grid through pumps located in the Clear Water Pumping Station. This station has six pumps, each capable of delivering 2100 m3 of water per hour with a total head of 60m. The sludge from the plant is disposed through a pump-house to the Sludge Drying Ponds having a total volume of 1100 m3.
The Primary Grid runs from Serampore to Chandannagar Garh in the north and to the Bally Khal in the south and crosses the railway lines by tunnels under the tracks. The pipe materials used range from the conventional Mild Steel (spirally welded and plate fabricated), Cast Iron and Pre-stressed Concrete to the non conventional Glass Fibre and Ductile Iron. The pipe dia ranges from 600 mm to 1200 mm.
There is also a system of 21 Km length of secondary grid pipes in 20 branches with diameters ranging from 300 mm to 400 mm for conveying the water from 20 take-off points on the primary grid to municipal zone centres. Seventeen out of these branches terminate at Under Ground Reservoirs (UGR) - capacities of which range from 0.9 to 2.5 million litres and the other three end up in existing Overhead Reservoirs (OHR). The integration with the existing Municipal Water Supply system takes place at the UGRs or OHRs, which act as the nodal points for distribution of safe drinking water to the consumers.
Project Costs
The construction cost for col lection, pumping, treatment and storage units at the Head Worts is Rs. 12 Crores and the cost of laying 27 Kms of Primary Grid is another Rs. 16 Crores.
4400 m3 per hour capacity Water Treatment Plant at Serampore
Utilisation of diaphragm wall as a structural member in Raw Water Pumping Station: First in India.
Use of glass-fibre reinforced pipe in the Water supply field through 1100 mm dia Raw Water Rising Main : First in India.
Production rate: Area ratio for a Conventional Treatment Plant 1548 m3/hour/Hectare: Highest in India and one of the highest in the World.
