Ahmedabad: From canals to your taps, here's how

The water's journey is actually quite impressive. From a lake or a reservoir (the source), to the nearest treatment plant and sometimes also the furthest, to finally reaching a commercial complex or a residential building, the journey is long, tedious and costly.

Ahmedabad is the largest city in Gujarat, and the administrative capital as well. It is also a crucial industrial and economic centre of power. Yet, water remains an ongoing issue in this city, which has a population of 5,633,927or 56 lakh (2011 population census), making it the fifth most populous city in India. Ahmedabad, formerly known as Karnavati, received a deficit rainfall of -48 per cent last monsoons.

FUNCTIONING OF TREATMENT PLANTS

Each treatment plant has three units for treatment. First stage is the screening where water passes through a cross-wire gauge with a tiny pore. Impurities which are bigger than the pore size get removed

The second is a chemical process. Untreated water has a neflometic turbidity unit (NTU) value. The water received by the city has a NTU value of 10, depending on the season. According to the WHO guidelines, the water should have 5NTU during summer and in winter it could be around 10 NTU. To maintain the WHO norms, chemical dosing is used. The water is treated with a dosage of aluminium sulphate alum. The process removes at least 90 of the impurities.

After this, the process of sedimentation comes into play. The water is made to settle which results in impurities getting settled at the bottom of the tank. The impurities are then dumped using a traction bridge. The water is then filtered by two methods — decline rate type and gravity sand filter. The second method uses a mould, normally called a filter media, made of fine coarse silica sand. The mould has 350 mm of gravels and 750 mm of fine silica sand. Impurities are rooted out through this process. At least 1,450 litre of water is filtered per second. Later, a back wash process is used in order to clean the filter media so that it isn't choked. This process is repeated every 6 weeks for maintenance.

The last stage of treatment is chlorination. Chlorination is done to remove the bacteria and odour from the water. Chlorination gas is used for this final stage.

24/7 METERED WATER PROJECT

At present, AMC is working to provide a 24/7 metered water to citizen. For the pilot project, three wards – Jodhpur, Naranpura and Vadaj — have been selected. A Water Policy will be drafted for the same, in which citizens will get water round-the-clock, by paying charges as per the metre. Currently, 30% of the general tax is being considered as water tax per property occupier in AMC jurisdiction

NEW ADVANCE TECHNOLOGY: SCADA

Smart City Project Supervisory Control and Data Acquisition (SCADA) has been set up for round-the-clock monitoring of the water treatment and the distribution system. The project has been set up for three water treatment plants and 148 water distribution stations. It will monitor the quantity and the quality of water supplied in various areas

WATER TREATMENT PLANTS

Raska Treatment Plant: Till 2000, AMC took water from the Dharoi dam, which is located 150 km away from the city. Back then, water scarcity arose due to insufficient monsoon. When the AMC realised that the city may face a water crisis that summer, a canal was constructed within a time span of 180 days. This project, called the Raska Project, is now the main source of water for the city. The work was completed at the cost of Rs 100 crore. The Raska Project, at that time, supplied 300 MLD of water taken from the Mahi canal.

For the project, water from Mahi river is routed from the Vanakbori weir or a low dam, through the Mahi canal, till the tail-end of the Shedhi branch canal near the Zinger village. A water pump house has been constructed towards the end of the Shedhi canal, to handle 130 cusecs of water. Water is then pumped to the Kotarpur plant through its 32 km-long pipelines

Kotarpur treatment plant: The Kotarpur treatment plant was constructed by 1987 with a capacity of treating 650 MLD of water in 24 hours. Surface water from Dharoi dam was used. In 2003 and 2006, two intake wells, with a capacity of 165 MLD of water and 330 MLD of water, were constructed. By 2006, Narmada's water reached Ahmedabad

Jaspur treatment plant: To cater the daily water need of North-West Zone and South-West Zone, the Jaspur water treatment plant was commissioned in 2006 with capacity a of 275 MLD of water, which is now at 400 MLD

30% – cut in the water supply for the rabi crops. Of the total 17,654 cusecs of water being released into the Narmada Main Canal, 13,500 cusecs has been allotted

Water treatment in pictures 

The length of Narmada canal network is envisaged at 71,746 km (which would finally be around 69,000 km due to reasons such as urbanisation, de-command, among others). Of this, 50,795 km canal network is already in place.

In the inlet area of the treatment plant, three essential functions take place: The raw wastewater must be transported to pump stations without disruption. At the same time, the flow rate and level of the wastewater are measured.

Main pumping stations, which supply water to the distribution system, are located near the water treatment facility or a potable water storage facility, and pump directly into the piping system

The mission of the Central Laboratory is to “provide water, wastewater and water treatment, chemical testing services for physico-chemical and microbiological parameters, and perform analytical services”.

CENTRAL LABORATORY

Monitoring the quality of the water quality is the main task assigned to the Central Laboratory, which was established in 1976-77 and upgraded in 2014. Samples of drinking water are collected and analysed for physico-chemical and bacteriological analysis on a daily basis. These water samples are collected from the water treatment plants, french wells and isolated AMC bore wells in and around its jurisdiction

6,500 to 7,000 samples are analysed at the central laboratory every month. An equal no of samples are checked for residual chlorine level as well. The laboratory works according to the WHO guidelines and the Indian Standard Specifications — IS 10500: 2012 on the Drinking Water Quality

LEGEND HAS IT

Legend has it that it was Shiva who brought the goddess Ganga to Gujarat and that is how Sabarmati came into existence. In the years gone by, Sabarmati river was known as Bhogwa. The river takes credit for 'hosting' (so to speak) two of Gujarat's most important cities — Ahmedabad and Gandhinagar. Ironically, this river, which is historically rich and known world over, does not supply a drop of water to Ahmedabad city's resident. Sabarmati's water is only used for irrigation purposes for farmlands

• AMC purchases water for Rs 3.14 per 1,000 litre. (Every year in April, the cost increases by 10 per cent)
   
• Cost for a resident 30% of the general tax

City’s water sources (Narmada main canal/Shedhi Branch Canal/Dharoi dam)

Underground mild steel pipeline (Diameter varies from 2,500 mm to 2,000 mm)

Water Treatment Plants (Kotarpur, Jaspur and Raska)

Through underground mild steel and ductile iron pipeline (Diameter varies from 2,100 mm to 450 mm)

Water Distribution Station (192 WDS in the city)

Through underground ductile iron and cast iron pipeline (Diameter varies from 70 mm to 150 mm)

WATER SUPPLY INFRASTRUCTURE

• Water supply 1,290 million litre per day (MLD)
   
• Water treatment plants 3
   
• Water distribution stations 192
   
• Water trunk mains 400 km
   
• Water distribution network 4,005 km.
   
• Population coverage by water supply 92%
   
• 90% with surface source, 10% with ground water
   
• U/G & OHT storage capacity (192 WDS) 1,391.22 ML
   
• Per capita water supply 140 to 160 LPCD