The mound downslope side should also be no steeper than 3:1 (rise:run) for safe mowing. Since the site slopes away, a downslope width correction factor is required for the width adjustment. The downslope width correction factor can be calculated as 1/[1 - (Mound side slope factor, or run)*(Site slope)]. Downslope width correction factors are provided in Table 4 for a 3:1 mound side slope for various site slope. (Note: Downslope width normally is larger than basal width.)
| Table 4. Downslope Width Correction Factor for a 3:1 Mound Side Slope | |
|
| Site Slope (run/rise) | Correction Factor | |
|---|---|---|
| 1 | 1.03 | |
| 2 | 1.06 | |
| 3 | 1.10 | |
| 4 | 1.14 | |
| 5 | 1.18 | |
| 6 | 1.22 | |
| 7 | 1.27 | |
| 8 | 1.32 | |
| 9 | 1.37 | |
| 10 | 1.43 | |
| 11 | 1.49 | |
| 12 | 1.56 | |
| 13 | 1.64 | |
| 14 | 1.72 | |
| 15 | 1.82 | |
Downslope Width = (Mound side slope factor, or run)*(Mound sand fill downslope depth + Aggregate depth + Distribution protection depth)*(Downslope width correction factor)
Downslope Width:
The recommended mound side slope is 3:1 in this design example and the corresponding downslope correction factor is 1.56.
| Downslope Width | = (Mound side slope factor)*(Mound sand fill downslope depth + Aggregate depth + Distribution protection depth)*(Downslope width correction factor) |
| = (3)*(28 inches + 9 inches + 6 inches)*(1.56) | |
| = 201 inches | |
| = 16.75 ft |