The project to strengthen Red Hills reservoir, the city’s major drinking water source, has taken off after several decades. The work gains significance as some of this work is being carried out for the first time since the reservoir was built in 1876. Up until now, the WRD has only taken up maintenance work worth Rs.5 lakh every year on the reservoir.
The Water Resources Department (WRD) has initiated the project at a cost of Rs.10.56 crore. Work is already progressing to plug holes in the two masonry weirs of the reservoir.
Officials of the WRD said while one weir is 178 metres long, the other is 220 metres long and 15 feet deep. The reservoir was originally a small tank with a capacity of 500 million cubic feet (mcft) and the structures then functioned as surplus weirs to release excess water from the water body. Now, these masonry weirs are water-retaining structures as they have been replaced by two shutters.
In 1997, the storage capacity of the reservoir was increased to 3,300 mcft and the depth to 21.20 feet to cater to the drinking water needs of Chennai and also to store Krishna water received from Andhra Pradesh.
“These weirs were built using locally-available laterite stones and they have turned porous over the years. We are drilling holes at regular intervals in the weirs and plugging the pores with a mix of cement slurry. This is probably the first time that the structures are being strengthened since the reservoir was constructed,” said a senior official. Also, the rear portion of the weirs are being stabilised and this work will be completed in two months.
The department is also planning to start repair work of the two shutters. “We are also widening the bund from the existing 5 metres to 7 metres to increase its stability. Filter arrangements on the earthen bund will be provided to collect the water seeping and to dispose of it. Otherwise, seepage will spread across the bund and affect the structure,” the official said.
there is also a proposal to fence the area along GNT Road and install sentry boxes. The bund runs to a distance of 7 km, and often people gain entry through the open, water-spread area and misuse the water body. However, the length of the bund cannot be extended as it would prevent run-off from the catchment areas from entering the water body.
The water level of the reservoir was brought down to 10.46 ft to take up the project. At present, the water body receives 300 cubic feet per second (cusecs) from Poondi canal to supply to the city. The project is expected to be completed in a year.
