Catch Basin Spacing Calculator
Calculate maximum catch basin (inlet) spacing based on gutter flow capacity, cross slope, and design rainfall intensity.
Inputs
ft/ft
ft/ft
ft
ft
in/hr
Results
Maximum Inlet Spacing
2,330 ft
Inlets per 400-ft Block
1
Gutter Flow Capacity1.87 cfs
Inlet Intercept Capacity1.54 cfs
Inlet Efficiency82%
How to Use This Calculator
- Enter roadway longitudinal slope (%), cross slope (%), gutter width (ft), and maximum allowable spread (ft).
- Set rainfall intensity (in/hr) for the design storm event.
- Review Maximum Inlet Spacing (ft) and Inlets per 400-ft Block.
- Use this to plan storm drain layouts during roadway design or retrofit projects.
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