🌿 EPA / ASCE LID (Water Quality Volume WQv Acre-Feet, 24-48 Hour Filter Drawdown)

Stormwater Bioretention Basin Calculator

Size urban stormwater bioretention basins and rain gardens under EPA Low Impact Development (LID) & ASCE guidelines: calculate required Water Quality Volume (WQv in Acre-Feet based on 90th percentile storm event and watershed impervious fraction), calculate ponding surface area, verify complete 24 to 48 hour drawdown, and civil contracting profits.

1. Project & Operating Inputs

Contributing Watershed Area (Acres e.g. 15.0 Acres Commercial Development)

Watershed Imperviousness (% e.g. 75.0% Parking Lot / Roof Surface)

Customer Invoiced Bid Price for Excavated & Planted Bioretention Basin ($)

Mass Grading, Engineered Soil Media, Native Plants, Underdrain & Tech ($)

2. Financial Breakdown & Yield

EPA LID BIORETENTION

Turnkey Bioretention Basin Project Profit

Civil Stormwater Contracting Margin

0.0%

Gross Revenue / Bill

Total Project CapEx

Operating / Direct Cost