File:HY8image16.jpg

The input variables required for this calculation is the following:

• Baffle Block Height Ratio — The ratio of the baffle block height to baffle block distance from the culvert.
• End Sill Height to Maximum Depth Ratio — ratio to determine the end sill height from the maximum depth.
• Basin Width — The channel width is recommended for the basin width.

The following figures show the design of a Contra Costa basin.

Variables from the figure

• D — Diameter of culvert
• y₀ — Outlet depth
• y₂ — Approximate maximum water surface depth
• y₃ — Basin exit velocity
• V₀ — Outlet velocity
• V₂ — Exit velocity
• h₁ — Height of small baffle
• h₂ — Height of large baffle
• h₃ — Height of end sill
• L₂ — Length from culvert exit to large baffle
• L₃ — Length from large baffle to end sill
• L_B — Basin length