Design Calculators
Engineering-grade sizing tools with documented methods, visible intermediate steps and printable worksheets. All calculations run in the browser — nothing is uploaded.
Dry Swale Design Calculator
Dry swale design from definition to detail: channel geometry, engineered soil media and underdrains, check dam spacing, and a fully worked two-fork design example.
Open calculatorStormwater Pond Design Calculator
Size a stormwater pond against the full volume stack — water quality, channel protection, overbank and extreme flood — with outlet hydraulics and a fully worked 38-acre example.
Open calculatorSimple Method Runoff Calculator
Annual runoff volume and pollutant loads from drainage area and impervious cover.
Open calculatorSand Filter Design Example
Worked sizing example for a surface sand filter — treatment volume and filter bed area.
Open calculatorInfiltration Trench Design Example
Worked sizing example for an infiltration trench — recharge, storage and drawdown checks.
Open calculatorPollutant Removal Database
Median removal efficiencies by practice and pollutant, with sources.
Open database