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Sediment Basin Sizing Calculator

Size a construction sediment basin from the disturbed area draining to it, on the standard storage-per-area rule.

Computed in your browser — nothing you enter is uploaded. Figures are presented in United States units and terminology, and each formula’s basis is cited under regulatory standards below.

Last verified 2026-08-27 · v1.0.0

Market
Imperial · sales tax

Basin storage volume

791 yd³

Check your inputs

The storage-per-area rule is a widely used screening basis. Your permit may instead require a design-storm calculation, which can give a materially different volume.

Drainage area
4.94 acres
Drainage area in acres
4.94 acres
Wet storage
659.21 yd³
Sediment storage
131.84 yd³
Total in cubic yards
791.06 yd³
Clean out when sediment reaches
65.92 yd³

Running these inputs gives 791 yd³ as the basin storage volume. Total in cubic yards carries the most weight in this calculation, at 791 yd³. Expect some drift against the real job; the calculation is solid but conditions on site are not. Currently reading for United States — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.

Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Regulatory standards & verification citations

  • 3,600 ft³ of storage per acre of disturbed drainage area — the sizing rule used in the EPA construction general permit and in most state SWPPP manuals
  • Equivalent metric rate: approximately 252 m³ per hectare of disturbed area

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Frequently asked questions

Where does 3,600 cubic feet per acre come from?
It is the storage rate used in the federal construction general permit and carried into most state stormwater manuals — a screening rule that gives a basin enough volume to settle out the sediment a disturbed acre typically produces in a design event. Its metric equivalent is about 252 cubic metres per hectare. Several jurisdictions have moved to a design-storm calculation instead, which is why the rate here is editable.
Can I reduce the basin by diverting clean water?
Yes, and it is the most effective thing you can do. The rule sizes against disturbed area draining to the basin, so run-on from undisturbed ground that you route around the basin instead of through it comes straight off the requirement. It also improves performance: diluting sediment-laden water with clean water does not help it settle.
Why does the basin need dead storage below the outlet?
Because it captures sediment, and that sediment accumulates in the bottom. Without an allowance below the outlet the basin loses its working volume as the job progresses and eventually passes sediment straight through. The allowance buys time, and the clean-out trigger — commonly half the sediment storage — is what actually keeps it working.