MANAGEMENT OF WATER SUPPLY DURING ACUTE WATER SCARCITY IN 2003 - 2004

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  1. As on 1st January 2003, the combined storage in the three lakes viz. Poondi, Cholavaram and Redhills which form the surface source for Chennai City water supply was 2,907 Mcft out of the total capacity of 7,412 Mcft and in Chembarambakkam lake, which is also supplementing the Chennai City water supply, the storage as on 1.1.2003 was 792 Mcft against the full capacity of 3,645 Mcft.

  2. There was no scope for getting any substantial quantity of water from the Telugu Ganga Project before October - November 2003. The ground water source from the Araniar Koratalaiyar Basin located in the North of Chennai City was also depleting due to poor rainfall continuously for the past 2 to 3 years. In view of this situation, it was resorted to supply water to the Chennai City on alternate days through pipeline with effect from 18.1.2003 at the rate of 175 ML on supply days and 25 MLD on non-supply days through tanker lorries.

  3. In view of the available poor storage in the lakes and also there was no prospect of getting any appreciable quantity of water from the Telugu Ganga Project, owing to poor storage in reservoirs there, measures were taken to maintain the minimum requirement of water to Chennai City by taking up various drought contingency measures. Under the drought contingency programme, more number of agricultural wells were hired from the Araniar Koratalaiyar Basin area, pipe laying work, construction of sump and pumping arrangements were carried out on a war footing. The quantum of extraction of ground water was gradually enhanced from 60 MLD to 100 MLD from July 2003 onwards. Simultaneously, system improvements were carried out by laying higher size transmission main in Redhills and in Well Field area to convey more water to the 300 MLD Water Treatment Plant at Redhills. Also, action was taken to lay 1000mm f Ductile Iron pipe from Poondi to the underground tank at Redhills Water Treatment Plant for conveying about 40 MLD of ground water from the hired agricultural wells in Poondi Well Field area.

  4. Further, to augment the water supply to maintain the minimum supply levels in Chennai city, water was conveyed through tanker lorries from distant sources located at Mamandur, Palur, Karunguli, Thiruporur area, Poonamallee area, Minjur, Panjetty, Gummidipoondi and Kannigaiper area. Water from distant sources ranging from 130 to 150 km distance was transported at the rate of 4 MLD during July 2003 and stepped upto 100 MLD during the month of May 2004. This stepping up of distance source water was coordinated with the fall in the yield of the Bore wells in the Well Fields in Araniar Koratalaiyar Basin so as to maintain the total availability of water.

  5. Since there was no improvement in the storage of water supply and no water was received under the Telugu Ganga Project, piped water supply to Chennai City was stopped from October 2003. Thereafter, the water supply to Chennai City was maintained through tanker lorries by filling 14,600 HDPE/Steel tanks erected all over the city and also by organising about 7000 number of street supplies by operating about 13,000 trips per day. Due to continuous drawal of ground water source, the extraction which was at 100 to 105 MLD in May 2004 was gradually reduced to about 50 MLD in Sep. 2004 due to depletion of water level. For meeting the people's need for water, for other than drinking and cooking purposes, 1000 I.M.-II pumps were erected during 2003-2004 and 1,731 during 2004-2005 and the total pumps available/yielding were 6,327 including the pumps already existing.

  6. To maintain the minimum water requirement of the Chennai City, the Chennai Water Supply Augmentation Project-I (New Veeranam Project) was taken up and the works were commenced in November 2002, after finalising the tenders. The formal launching of the Project works was held on 2.2.2003 in a Government function at Cuddalore and the Chennai Metrowater was directed to execute this work on a war-footing so that the system will be ready to convey water to Chennai City in time.

  7. In July 2003 itself, detailed investigation and assessment was made in the Neyveli Aquifer for the extraction of ground water to meet the Chennai City's water requirement by utilising the Chennai Water Supply Augmentation Project's (New Veeranam Project) pumping system, pipeline and other infrastructures. Accordingly, 45 Bore wells were erected with submersible pumpsets (30 for operation and 15 as standby) in between Gadilam river and Paravanar river over a stretch of 30 km. based on a detailed investigation and recommendation for the extraction of 60 MLD from the Neyveli Aquifer by the Ground Water Wing of PWD. Necessary pipeline for connecting the Bore well water to the underground tank of Water Treatment Plant at Vadakuthu was also carried out. By the middle of April 2004, most of the works in the treated water pumping arrangements and treated water conveying mains from Vadakuthu to Porur were completed under New Veeranam Project.

  8. The initial trial operation and flushing of the pipeline using the Bore well water from the Neyveli Aquifer was commenced on 15.4.2004 and on completion of the trial operation, water was let out into the Porur lake on 31.5.2004. Since this water was used for flushing the pipeline, upto 14.7.2004, the water extracted from the Neyveli Aquifer was let out into the Porur lake and re-conveyed to the Kilpauk Water Treatment Plant for treatment and supply to the Chennai City. On completion of the flushing of the pipeline and after stabilization of the pumping and pipeline system of the New Veeranam Project, water was pumped from the newly constructed Porur Water Distribution Station to the Chennai City pipeline grid system with effect from 14.7.2004.

  9. Total quantity of about 7,546 ML was pumped from the Bore wells at Neyveli Aquifer from 15.4.2004 to 13.10.2004. The water level fluctuation and quantity of water in the Neyveli Aquifer were closely monitored by analysing the details from April 2004 onwards i.e. from the beginning of the extraction of water from the Neyveli Aquifer to Chennai City. Eventhough the overall extraction from April 2004 to October 2004 for Chennai City water supply was 7,546 ML, the water table raised from the original level before pumping of about 67.40 metre (average) in May 2004 to 63.40 metre in November 2004 due to frequent rain in that area and also due to controlled extraction from the Bore wells. In respect of quality of water, it was found that the TDS level was between 130 and 660 mg/lit. before pumping and during pumping, the TDS was observed as 100 - 600 mg/lit. and as such, there was no deterioration in the quality of water due to the extraction of water for Chennai City from Neyveli Aquifer.

  10. The Chennai Water Supply Augmentation Project-I (New Veeranam Project) was fully commissioned with trial operation commenced on 16.9.2004 by drawing water from the Veeranam Lake. On completion of the trial operation, drawal of water from Veeranam Lake started from 20.9.2004 and the extraction of ground water from Neyveli Aquifer was reduced gradually in tune with the increased drawal from Veeranam Lake and stopped completely with effect from 13.10.2004. The entire scheme was in full operation with effect from 13.10.2004 afternoon. Taking advantage of the increase in storage of the Veeranam Lake due to local rains and also receipt of water from the river Cauvery/Kollidam, alternate day water supply through the pipeline was commenced on 13.10.2004. From 10.11.2004, the transportation of water from distant sources was completely stopped since the major contribution of city water supply was made by the receipt of 180 MLD from the Veeranam source. Daily piped water supply was commenced from 01.11.2005. due to the normal rainfall during the monsoon 2005.
   
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