Bowbridge Spill Weir
About two weeks ago, work was carried out to investigate a potential blockage in the spill weir at Bowbridge. On the odd occasion, it has over topped and water has flowed into a neighbours patch.
With some material extracted from that exercise, mostly junk thrown in during the house construction nearby, it seemed appropriate to undertake a test to see if there had been any improvement. Our concern is that under flood conditions, the problem might be repeated.
Yesterday, Gough's Orchard syphon feed was set going with the intention to fill the canal all the way to Bowbridge, so that the maximum we can achieve was being bypassed round the lock. Then, under a controlled test, the paddles at Griffin Mill would be lifted and send a lock full surge down to Bowbridge and see if it could cope.
Most of these conditions were met this morning. There was a reasonable flow over the weir, however, the syphon had stopped a few hours earlier due to a lack of battery power (we understand why). There was no quick way to restart it, so the test went ahead anyway.
By cycling up to Griffin Mill, to open the paddles, it is possible to get back to Bowbridge before the surge wave appears. Watching the arrival of the water and seeing the change in conditions was most interesting. Quite dramatic, in fact.
You can just see the brick arch of the inlet in this image
Observations of the inlet and outlet points confirmed that the bypass conduit was handling the flow well with still plenty of room at the top of the feed aperture. Some polystyrene beads were ejected from the outlet, possibly more to come.
This test will probably be repeated on Monday, given we are happy that full flow conditions across the pounds have been met.
