VII. ECONOMIC CONSIDERATIONS 



An economic analysis of revetment plans can be made by comparing 

 initial construction and design-life maintenance costs for the revet- 

 ments considered to select the final design. Some design considerations 

 are organized into a matrix which can be used to compare alternative 

 revetment designs (Table 1). 



Table 1. Revetment analysis matrix. 



The size of the matrix will depend on the number of independent vari- 

 ables allowed to change in an analysis. These independent variables are: 



(a) Revetment type, 



(b) design life, 



(c) allowable damage, 



(d) revetment slope, 



(e) filter type (semi-independent), and 



(f) toe type (semi-independent) . 



VIII. USE OF THE MATRIX 

 The following is an example of how to use the matrix (Table 1) : 

 *************************** EXAMPLE PROBLEM ***************************** 



GIVEN: 



(a) 100 feet of low bluff on Lake Superior is eroding. 

 Bluff slope is about 1 on 3. 



(b) Design life, 20 years (selected). 



(c) Design wave H = 5 feet at toe of structure; 

 period T = 7 seconds. 



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