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Tables (for airfields)
Compute the number of pipes.
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Np = Qdes divided by Qpipe
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Qpipe is obtained from a pipe capacity table.
Compute length.
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In place length = S1 (width of slope) + width of road (or runway) + S3 (width of other slope =
__________ round up to next even number and add 2 feet, if no headwall downstream.
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Order length = (In place length) (1.15). Round up to the next even number.
Check outlet velocity, V. If V is greater than Vmax provide erosion protection, or select a pipe of a
smaller diameter.
Use the smallest pipe with the least number of pipes.
EN5465
5-22