BMC ‘well’ in time for rains…………Sukhada Tatke
MUMBAI: The dark clouds are expected to keep their date with the city this year and hopefully bring bright tidings for the water reservoirs. With the weather bureau predicting a normal monsoon that will most likely arrive in the first week of June if not end-May, the BMC hopes the rains fill up the catchment areas this time around. But it is not taking any chances.
An unusually hot and early summer sapped most reservoirs dry, some lakes reaching their lowest drawable levels. As the city started feeling the pinch of the water cuts, the civic body resorted to traditional methods like digging wells to supplement the lakes, besides cleaning existing wells to increase capacity. The rains less than three weeks away, the BMC now plans to dig more wells in the next two months, so it can tap groundwater even if the lakes don’t suffice.
Last week, the civic standing committee passed a proposal to dig 100 ring wells in the city. The construction will have to be undertaken in addition to the civic bodys ongoing work of digging new borewells and cleaning the existing ones. The BMC has appointed three contractors—one each for the eastern suburbs, western suburbs and the city—to construct new ring wells.
“We have allocated Rs 40 crore to de-silt and repair the wells, besides Rs 10 lakh per filtration plant. The water from the wells will be used for non-potable purposes such as gardening, flushing and can be put to other non-drinking uses,” said Vinay Deshpande, BMC’s hydraulic engineer, adding, “We identified wells in each ward and got all of them cleaned. In areas where there were no wells and corporators or residents had put in requests for constructing the same, we did a feasibility check and then dug the wells.”
An official said the city has around 7,000 borewells and 5,000 dugwells, which have the potential to yield 600 million litres per day (MLD). While the figure is not enough for the city, considering that Mumbai uses 70% of its water for non-potable purposes, even in a good monsoon, the BMC can reduce pressure on reservoirs by tapping these alternate sources for non-potable water.
A report by the hydraulic department shows that there had actually been an overall increase of 8.77 lakh litres of water in the wells after the municipal corporation cleaned and desilted more than 100 underground wells earlier this year.
Geologist S K Gupta conducted a survey for BMC to check groundwater status two months ago cautioned, “Wells can’t be dug haphazardly and the groundwater table needs to be taken into consideration.”
However, he said, since the quantity of water in the wells is directly dependent on the surcharge level in the ground, the wells would be of no use if the rains are inadequate this year. In fact, earlier this year, a civic-appointed team of geologists suggested that the many existing wells be dried to allow them to be refilled when the next monsoon arrives. Once it rains, water will seep into the underground rock layers and act as a natural rainwater recharge. One way to do it, say officials, is rainwater harvesting, by which the run-off of the surrounding surface water can be captured and act as a natural recharge.
Owing to the delayed and insufficient rainfall last year, the stock in the lakes in catchment areas is lower than needed. While at least 13 lakh litres of water is necessary in all the lakes to be able to sail smoothly through every year, last year’s rainfall barely managed to fill up 10 lakh litres.
“The water in the wells is naturally proportional to the rains. A good monsoon will mean more water stored in the wells which can be of help in the dry period post-October,” said a hydraulic department official.