Hogfan, I suggested heppy make the vent supply line (for water to raise and lower in) to be always angled downward into the pond pool....it will not matter if soil or grass enters the supply pipe....the crud will migrate into the pond...the hole into the supply pipe does not even need any seal at all. If water rose, it is on the pond side of the dam core, so no harm getting things wet, and again, any soil entering would be a minor, meaningless amount. there is no danger of erosion...Last, if your dam "settles" much, if at all, it was never compacted and constructed properly to begin with.
I also suggested installing an access basin around the vent tube crossover and vent supply pipe...and adding valve in the vent tube, along with another TEE on the vent tube between the siphon and valve, so the siphon can be manually started in case you need to do a draw-down or draining of the pond
The vent supply pipe does not need the TEE, only the siphon inlet. Capping the supply pipe, and drilling a couple 1" holes at the lowest point will keep it clear, and then several 1/2" holes elsewhere will allow it to easily stay at pool level.
Last edited by Rainman; 08/28/18 09:11 AM.
