Real sediment-basin sizing, RUSLE soil-loss, Camp's-equation, and forebay-design problems — solved end-to-end with every formula, every assumption, and every number shown. Each example uses the same SEDCAD4 engine that powers the HydroComplete app, so you can open the scenario and tweak any input.
Full RUSLE → Camp's → 7-bin Stokes/Camp pipeline on a Charlotte residential subdivision. Comes out at 65.5% trap efficiency — below NCDEQ's 80%, so the example walks through forebay/PAM/upsizing remediation.
Same 1-acre Asheville site solved four times: bare grading, straw mulch, erosion blanket, temporary seed. Shows where the C-factor row in the RUSLE table actually moves the needle.
Inherited a basin design from a similar prior project. Run the math before submitting: A_s and Q give the capture particle, then 7-bin Stokes/Camp gives 67% trap efficiency — below NCDEQ. What to do.
A widely-repeated rule says forebays raise trap efficiency. The math says otherwise: 65.5% → 66.0% with 10% forebay, → 67.0% with 40% forebay. Forebays do other useful things — but they're not a capture-rate fix.
Same 5-acre basin from scenario 1. With 5 ppm anionic PAM dosed at the inflow, the 7-bin trap efficiency moves from 65.5% to ~92% — without enlarging the basin. Dosing rate, application methods, cost, and the NPDES turbidity story.