For 24x7 water, relay pipes and revise design: New advisor

Nagpur: Supposed to be completed six years ago, the city faces a wait of a few more years to get 24x7 drinking water supply. The newly-appointed advisor has suggested laying of new pipelines, construction of more overhead water tanks, retrofitting works, installation of heavy pumps, revision of entire design, detection and repair of leaks in all areas before 24x7 water supply reaches the entire city.Honorary advisor Sanjay Dahasahasra, in his report submitted to Nagpur Municipal Corporation (NMC), claimed drinking water can reach all consumers this year if some short term works are implemented.

“There are 68 elevated service reservoirs (ESRs), so 68 operational zones or command areas. Currently, 24x7 water supply is available in some areas of 33 zones. However, water does not reach taps of all residents in many zones. Most consumers have constructed underground storage tanks as water does not reach even the first floor. Therefore, there is a need to revisit and redesign water supply arrangement,” the advisor observed.Dahasahasra studied the hydraulic models of three zones — Nara Existing, Nara Amrut and Anandam. “Residual nodal pressures are designed for about 8-12m. Operator Orange City Water Private Limited (OCW) throttled isolation values installed at ESRs to maintain 2m pressure. If these valves are opened, it was apprehended that existing pipelines may burst as pressure at highest elevation mode goes beyond 2m at critical nodes. But the system has failed to fulfil condition of even 2m, as water is not reaching some places,” the advisor said.Dahasahasra also said fears of bursting pipes are unfounded. “Existing pipes can sustain maximum 26m residual nodal pressure,” he said. He suggested a model to increase pressure, so water reaches all households in these three zones. “After studying hydraulic model of other zones, this process can be adopted everywhere,” he said.The advisor has stressed the need to install variable frequency drive pumps at all ESRs. Currently, water reaches households with pressure created automatically as water is released from ESRs.Dahasahasra said a major discrepancy in the design of the zones is that they are oversized. “Each zone has over 3,000 connections. They should be divided into two district metering areas (DMAs). For this, retrofitting of existing network, removal of few existing pipelines and addition of more is required.”The NMC has already executed works worth over Rs1,000 crore for replacement of 700km pipeline, and Rs700 crore to replace pipelines over 400km, and construction of more 45 ESRs etc.NMC, in reply to advisor, requested for more details and estimated cost of the suggested works. “Designs were prepared with 12m residual head, not 2m. Trying to increase pressure beyond 12m would mean either changing diameter of existing pipelines and retrofitting works, which would lead to additional financial burden,” it said.