22 CAR § 111-1104
| CONDITIONS | MAXIMUM | MINIMUM | PREFERRED | ||
| Swale side slopes | 10% | 10:1 | 1% | 100:1 | 2% |
| Longitudinal slope of swales-grass invert | 8% | 12:1 | 1% | 100:1 | 2% |
| Longitudinal slope of swales-paved invert | 12% | 8.3:1 | 0.5% | 200:1 | 5% |
| Ditch side slope-grass invert | 8% | 12:1 | 1% | 100:1 | 3% |
| Ditch side slope-paved invert | 10% | 10:1 | ---- | ---- | 6% |