Leap Weirs

A leaping weir is formed by providing a gap in the invert of a sewer through which the dry weather flow falls and over which a portion or all the storm flow leaps forward. Leaping weirs have the advantages of operating as regulators without moving parts, but they often have disadvantage of concentrating grit in the low-flow channel. During a storm all flow may leap over the gap, stopping the flow in the low-flow channel with an undesirable effect on the sewage treatment plant being fed by that channel.

The falling stream may be made to pass through a sloping rack or grating to divert stones and other falling objects from the interceptor. The grating should be sloped steeply to prevent paper and leaves from sticking to it, and a channel should be provided to divert drippings from the grating back to the dry weather interceptor.