How is bioretention cell area determined?

A_bio = WQV / (k × Δh + d_surface), where WQV is the water quality volume (typically the first 25–40 mm of runoff from the contributing area), k is the media hydraulic conductivity (typically 25–50 mm/hr for engineered media), Δh is the ponding depth, and d_surface is available storage depth. Per US EPA Low Impact Development Manual (EPA 841-B-00-003).

What sizing ratio is typically used for bioretention cells?

Common guidance: bioretention cell area = 5–10% of contributing impervious area. Many jurisdictions require sizing for the 1-inch (25 mm) water quality storm with 24-hour drain time. The Minnesota Stormwater Manual recommends a minimum infiltration rate of 25 mm/hr for the underdrain setback zone and a media depth of 600–900 mm.

Bioretention Cell Sizing Calculator

Size bioretention cells (rain gardens, bioswales) for stormwater volume capture and water quality treatment per local LID design standards.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Size bioretention cells (rain gardens, bioswales) for stormwater volume capture and water quality treatment per local LID design standards. Use the bioretention sizing result to inform your clinical assessment.

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Frequently Asked Questions

How is bioretention cell area determined?

What sizing ratio is typically used for bioretention cells?