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sci.stormwater-runoff-pollutant Calculator
Calculates the first-flush pollutant load in stormwater runoff from event mean concentration and runoff volume. The first flush effect: the initial 20% of runoff carries 50–80% of total pollutant load — treatment systems sized to capture the first 25 mm are often the most cost-effective.
Inputs
Runoff Volume M3
Three-dimensional space occupied (m³ or L). 1 m³ = 1,000 L.
Emc Mg L
Amount of solute per unit volume. Higher concentration = more solute dissolved.
Removal Efficiency Pct
Useful output divided by total input, as a percentage. 100% is impossible due to losses (heat, friction, resistance).
Results
pollutant load (kg)
Sample size or count used in the calculation.
load removed by BMP (kg)
Reference formula or conversion factor shown for context.
discharged to receiving water (kg)
The value at the specified point or condition.
load = V × EMC / 1000
Reference formula or conversion factor shown for context.
TSS typical EMC
Reference formula or conversion factor shown for context.
phosphorus EMC
pH of the solution. Below 7: acidic. 7: neutral. Above 7: basic (alkaline).