On Monday, 5 August 2019 10:57:19 UTC+1, newshound wrote:
On 04/08/2019 23:26, wrote:
On Sunday, 4 August 2019 22:42:12 UTC+1, tony sayer wrote:

A lake near here was drained a few years ago for maintenance
of its dam. They used two siphon hoses each about 15cm diameter
and it took about two weeks.

Each hose had a strainer at the sucking end. I don't know how
the siphons were started, but they kept going happily until the
lake was nearly empty.

John


Presumably a non-urgent job?

Yes, the dam had been leaking for at least a year before they fixed it.
Here it is: 51.344159, -0.384329
They installed interlinked steel pilings on the upstream face once
the lake (called Middle Pond) was drained.
The outlet ends of the siphon pipes were not submerged - the flow of
water was enough to prevent air from bubbling back up. The pipe
diameter was something like 10 to 15cm.

John