How to Maintain a Weir Box
Although simple devices, Weirs Boxes do require periodic maintenance to provide accurate flow measurement.
THE WEIR BOX INSTALLATION
Inspect the weir pool floor, removing sediment and debris as necessary
Verify that the crest is horizontally and vertically level.
Verify that the crest is at least 2 Hmax above the maximum downstream water level.
Clean the crest of any debris, ragging, vegetative growth, etc.
Inspect the weir crest for nicks, burrs, rust, ice, or any other condition that affects flow over it.
Verify that the zero elevation at the point of measurement is the same as the bottom of the weir crest.
Inspect the weir plate / carrier for signs of leakage. While the weir plate / carrier are factory sealed, the stresses of shipment and installation may require that additional sealing be conducted after the weir box has been installed.
Inspect the inlet and outlet end connections for signs of leakage.
Downstream CHANNEL
If the discharge is free-spilling, inspect the downstream channel for signs of scour – reinforcing the channel as necessary.
Remove any debris, growth, etc. which may impede flow through the downstream channel.