Equation (1) is used to compute W15 (armor) 



W 15 (armor) = 0.4 * W 50 = 0.4 x 201 = 80 kilograms (179 pounds) 

 which is used to compute the minimum Wss (filter) using equation (3) 



D 15 (armor) (80/2,644) 1/3 /80 ^/ 3 



(80/2,644) ' 3 /80 \V 3 

 " (W85/2.644) 1 /? = V^j 



D 85 (filter) 

 which gives the minimum Wss (filter) = 1.25 kilograms (2.76 pounds). 



The maximum runup is computed using the three methods given in examples 3 and 

 4. Taking Stoa's (1979) method first, for d s /H = 1.2, the smooth-slope 

 reduction factor for runup on riprap, r, is given in Table 4. For a 1 on 

 1.5 slope, r = 60. The smooth-slope runup is computed by interpolating 

 between Figures 7 and 6 (Figs. 9 and 10 in Stoa, 1978). To use the figures, 

 calculate 



HI 



1.52 



gT 2 9.8(5) 2 



= 0.0062 



which gives 



rrf = 1.0 and £r = 2.63 (Fig. 7) 



"O No 



=7 = 1.5 and |j- - 2.43 (Fig. 6) 

 H o H o 



therefore, for ds/H^ =1.2, R/H = 2.55. Following the procedures illus- 

 trated in example 4, the maximum runup may be computed 



Rmax = R s (^r) = Cr) (Ho) (fr) ^g*- = (0.60) (1.52) (2.55) (1.25) 



= 2.91 meters (9.55 feet). 



Computing the maximum runup by the method developed in this report 

 requires using a = 0.956 and b = 0.398 in equation (8), thus 



R s 0.956 0.956 . , Q 



= ■ r-T = —. = l.HO 



H s 0.398 + (H S /L ) /2 cot 6 0.398 + (1 .08/39.01) 1/2 (1.5) 

 and the maximum runup is 



«-x-«.(^)-0..)(^)(^)-tt-08)(l.*8) 



1.25 



=2.00 meters (6.56 feet). 



Computing the maximum runup by the ETL 1110-2-221 method requires using 

 a = 1.0 and b = 0.40 in equation (8), therefore 



26 



