Table 3. Toe scour depth. 



Revetment 



Scour depth 



Reflection 

 coefficient 1 



Type 



Maximum 



possible 



(feet) 



Estimated 

 (feet) 



Riprap 

 Gabion mats 

 Lok-Gard blocks 

 Tire mats 



5 

 5 

 5 



5 



2 

 2 

 4 

 3 



low 

 low 

 high 

 moderate 



1. Appendix. 



Step 6. Slope Length : Revetment slope length is the sum of the 

 vertical elements converted to slope distance (Table 4): 



Table 4. Revetment slope length. 



Revetment 



Runup R 

 (feet) 



Water 

 level 



Water 

 depth 



(feet) 



Scour 

 depth 



(feet) 



Vertical 

 height 



Type 



Length 

 (feet) 



Range 

 (feet) 



Total 

 (feet) 



Riprap 

 Gabion mats 

 Lok-Gard blocks 

 Tire mats 



51.9 

 53.1 

 70.5 

 59.1 



4.4 

 4.8 

 8.3 

 5.7 



6 

 6 

 6 

 6 



4 

 4 

 4 

 4 



2 

 2 

 4 



3 



16.4 

 16.8 

 22.7 

 18.7 



Step 7. Armor Unit Weight : 



Riprap Revetment . Using Hudson's (1974) equation with 

 Kffi? = 2.2 to calculate stable rock weight (SPM, ch. 7), 

 the median riprap size is 700 pounds. 



Gabion Mat . Dimension 12 by 3 by 1 foot, nominal volume, 

 1.33 cubic yards filled with rock at 1.6 tons per 

 cubic yard. Unit weight 1.33 cubic yards by 1.6 tons 

 per cubic yard = 2.1 tons; each mat covers 36 square feet. 

 Estimated stable for H of 3 to 5 feet (App.). 



Lok-Gard Blocks . Interlocking block 23 by 8.6 by 5.6 

 inches; weight 75 pounds each. Stable for 5- foot wave 

 height (App.). 



Tires . Used car tires (26-inch outside diameter) bolted 

 through the tread and filled with sand cement. Weight 

 about 300 pounds each. Estimated stable for H of 3 to 5 

 feet (App . ) . 



17 



