During routine weir maintenance, which item should be checked?

• A. Volume of the basin
• B. Level indicator
• C. Power supply
• D. Wet bulb

Answer: (A)

Weirs discharge water based on the head, or depth, of water above the crest. Having adequate basin volume is essential because it lets the water level rise and fall with inflow without quickly hitting the top of the basin or overflowing, which keeps the head stable and the flow measurement accurate. If sediment buildup or debris reduces usable volume, level changes can become abrupt or readings can drift, compromising measurement and operation. While monitoring the level indicator helps you see the current head and the power supply keeps any electronic parts running, neither ensures the stable head that adequate basin volume provides. The wet bulb isn’t related to how a weir functions, so it isn’t a maintenance focus here.