The new windmill has been trying its best to be of service. There were a few anxious days when a part had to be replaced, the piping and pump to be changed and ways of managing it, to be understood. It pumps water now, but with some notable caveats. After digesting the unpleasant messages it delivered, I have learnt to see the pointReturn challenge very differently. Not only is the task greater, but solutions are more involved. The new windmill has already proved itself a wise and eloquent teacher.
The borewell at pointReturn is 6″ in diameter, and 200′ deep. Water stood at 20′ below the ground. It was reasonable to assume that there was plenty of water down there, as predicted by the diviner. We put in 60′ of 2.5″ dia pipe and fitted a 2.5″ pump. For each revolution of the wind-wheel, this pump will draw and deliver 1.2 litres of water. The maximum speed of the windmill is 60 revolutions per minute [rpm]. So it is quite easy to calculate the draw down per minute at maximum speed: 60×1.2= 72 litres per minute [lpm]. As the pump was 40′ below the water level, we assumed the water recharge will be steady and equal the draw down.
Within hours of the euphoria of the pooja on May 24, however the pump began to deliver erratically. It would go dry often and after a while, resume. The message was clear: the rate of recharge was slow.
In a few days, we replaced the existing arrangement with a 2″ dia pipe and pump and also lowered the whole thing to 120′. Being smaller, at full speed this pump would draw only 60×0.8 = 48 lpm. We expected this to solve the dry run problem. Indeed, it seemed it did. For over two days, it pumped quite well and then went utterly dry. Earlier with the 2.5″ pump, pumping would resume after a pause, but now not a drop came. The mill was stopped for several hours to allow recharge but that didn’t help either.
Speculation then began. We finally concluded that water was leaking past the piston or the foot valve. Why it should happen to a new pump was a mystery. The borewell was not suspect. Over a good part of two full days, the mill had pumped and the borewell had not run dry. We had to investigate.
We lifted the whole arrangement again – to discover the foot valve seal had broken to pieces. Naturally, the pump could not discharge. [Two days later, Aureka discovered a worker had fabricated the seal from some very old material stock] With renewed excitement, we lowered the pipes and the pump, its foot-valve now fitted with a new seal.
It began to pump steadily and after about 50 hours, it got erratic: it’d go dry, resume for a short while and go dry again. This stumped everyone. I was in deep despondency unable to understand the message from the mill. I then decided to sit still to visualise the goings on below ground where water lives. What I concluded was first very disheartening and then very liberating. I understood much about the realities of water and trembled at how little most of us know about a water famine we could be headed for.