After getting a few quotes to test the flow rate of our Well, the ‘mean gene’ kicked in and we did it ourselves.
This afternoon, someone said to me, ‘So, what is your scientific qualification to do this? Fighting the desire to say something appropriate, I said, “I failed maths at school”. When the expectations are low, you might as well live up to them.
Last weekend Dr Mike, philosopher of Maths, and I devised a test for our Well and tested it.
On Friday I rented the wrong pump. Our Well is 6 metres deep and luckily the pump arrived with a 2 metre hose. In the process of ringing to ask for an 8 meter hose, I discovered that if you want to test your Well, you should NOT rent a pump that needs to be primed and cannot be run ‘dry’.
Chosen pump would require us to pour enough water vertically down an 8 metre hose to fill it before we start the the pump. That’s a lot of water to pour into a well and I suspected it wouldn’t stay in the hose long enough for us to start the pump. (but mind you, I don’t have a scientific qualification!)
Photo below shows kindly rental firm coming to Easterdown on Saturday morning to bring us a generator + submersible pump. At no extra charge!
This is the kit:
Mike, the King of String!
All it takes is a bit of string and a bit of wood
Then you hook everything up with Jubilee clips
Using this as an excuse to teach me a bit of maths and making me do lots of adding up, Mike worked out that we have a refresh rate of a Gallon a minute. Not a great rate, but enough.
Mike worked out we have. conservatively, approximately 300 gallons in the Well at the moment, following a very dry spell. We expect to use less than the Environment Agency’s per person per day consumption ( 150 litres, pp, pd).
The well is 6.17m deep.
The water surface was 5.4m down and the pump occupied about 0.3m.
This means that we had about 0.5m of water above the pump.
We previously estimated the cross-sectional area of the well to be 1.17sq m, but let’s very conservatively say it is 1sq m (at that depth).
If we pump it down to 5.9m then it refreshes to 5.6m in 2hrs. This is 66gallons or 300 litres. We could do this every 2 hours. If we did it more frequently from 5.9m (say each half hour) then the refresh rate would be higher (by 50%).
The Environment Agency say that the per person per day water requirement is 33 gallons or 150 litres (but in the future households should use 20% less than this) so a household of 6 people would require three 2hr pump-refresh cycles.
The test Data:
21st September –
Initial depth (measured with string and a ‘bob’) to top of water 541 cm
After pumping till nearly dry – 596.5 cm
After 20 mins 589
After 5 hours 552
22nd September –
Initial depth – 541
after 20 mins – 589
596.5 to 589 -> rate .375 cm per minute (1st 20 minutes)
589 to 552 -> rate .132 cm per minute (4 hours 40 mins)
after 5 hours, still 7.5 cm to reach top (541)
20 hours later, the well was full again.
589 to 559.5 -> rate .25 cm per minute (1st two hours)
559.5 to 552.5 -> rate .12 cm per minute