Metro Rail construction teams are by now used to hitting huge hard rocks, utility pipelines and cables while laying foundations for piers and pillars.
However, they were in for a surprise few days ago when while digging on the Public Gardens – Telugu University line and the M.J. Market stretch, they encountered a decades-old Nizam era storm water drain. The drain, which was 10-feet deep, was not detected during the soil testing phase and came to the fore only when the excavation was taken deep for laying the foundation of the Metro Rail piers.
The storm water drain was functional and water was gushing through it at considerable velocity towards Chaderghat and Musi River. Officials, however, admitted that it was difficult to ascertain the origin of the drain.
“It’s a beautiful construction. Generally, we do not expect any pipeline at such depths. No one knew about it,” said Hyderabad Metro Rail managing director N.V.S. Reddy.
He pointed out that neither the GHMC nor the Water Board (HMWSSB) had any maps or drawings to show the existence of such a drain. The water might be flowing in from near the tracks adjacent to the Nampally railway station, which gets flooded during heavy rain, Mr. Reddy reckons.
The drain was also built in such a manner that the water flow was contained within the series of curves and could have been connected to underground storm drains with links to Lakdikapul and Masab Tank, officials said.
The challenge for the engineers of HMR and the concessionaire L&T Metro Rail Hyderabad (L&TMRH) would be to now build piers foundations in such a manner that they either circumvent the storm water drains altogether, by building an parallel pipeline of three metre-diameter or more.
