Institutional civil hydrology and stormwater economics model. Sizes commercial roof rainwater harvesting catchment runoff, calculates Rational Method peak storm flows (CFS), dimensions modular underground detention cisterns, models cooling tower make-up water displacement, evaluates municipal stormwater utility fee credits (30%–80%), and projects 20-year net present value (NPV).
| Civil Hydrology & Economic Metric | Underwritten Value |
|---|---|
| Peak Stormwater Runoff Rate (25-Yr Event) | 5.22 CFS (2,344 GPM) |
| Runoff Coefficient (C) • Smooth Membrane Roof | 0.95 (Impervious Surface) |
| Cooling Tower Water Make-Up Displacement | 100% of Harvested Water Utilized |
| Annual Sewer Discharge Fee Reduction | $9,050/yr (No sewer fee on evaporated water) |
| 20-Year Cumulative Operating Cash Flow | $512,400 |