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Permeable Interlocking Concrete Pavement (PICP) Infiltration Storage Calculator

Calculate the stormwater storage volume provided by a permeable pavement's aggregate reservoir layer.

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 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Stormwater storage volume

3,180 gal

Check your inputs

Void ratio depends on the specific aggregate gradation used — confirm the actual void ratio for your chosen open-graded base material (commonly tested per ASTM C29) rather than assuming a generic value.

Running these inputs gives 3181 gal as the stormwater storage volume. 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

  • Storage volume = surface area × reservoir depth × aggregate void ratio, the standard method for estimating the water storage capacity within a permeable pavement system's open-graded aggregate base

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Frequently asked questions

Why does storage volume depend on the aggregate's void ratio?
The open-graded stone in the reservoir layer is not solid — it has open voids between the stones where water actually collects. Only that void fraction of the layer's total volume (surface area × depth) is available for stormwater storage, which is why the void ratio directly scales the storage volume.
Should I use a generic void ratio like 0.4 for my design?
Only as a preliminary estimate. Void ratio depends on the specific aggregate gradation used, and should be confirmed for your chosen open-graded base material — commonly tested per ASTM C29 — rather than assumed, since actual values for open-graded stone are typically in the 0.3–0.4 range but vary by source and gradation.
Does this include storage in the bedding or choker course layers?
No — this calculates storage in the main aggregate reservoir layer only, using the depth and void ratio you enter. Additional storage in bedding, choker, or sub-base layers with different gradations should be calculated separately and added if applicable.