Step 8. Construction Cost : 



Develop quantity and cost estimates for all 

 revetments (Table 5) . 



Assume the following costs: 



Gabion mat (galvanized) $24. 



Riprap $8 per ton. 



Gravel $3.50 per ton. 



Cobbles (4- to 6-inch diameter) $3.30 per ton. 



Filter cloth — $0.15 per square foot. 



Used tires free. 



Cement — $0.03 per pound. 



Beach Sand (for sand cement) free. 



Lok-Gard blocks $1.25 each. 



Installation (estimated labor and equipment) — 

 $1 per square foot of revetment surface. 



Table 5. Quantity and cost estimates. 



Description 



Unit Quantity Unit cost 



Riprap (Coverage 100 feet X 52 feet = 5,200 square feet) 







Riprap armor W 50 = 700 pounds (3.25 feet thick) 



tons 



1,000 



$ 8.00 



$ 8.000 



Rock underlayer W 50 = 70 pounds (1.5 feet thick) 



tons 



460 



$ 8.00 



3,680 



Gravel filter (1 foot thick) 



tons 



310 



$ 3.50 



1,085 



Installation 



square feet 



5,200 



$ 1.00 



5,200 



Subtotal 



$17,965 



Total cost including 25-percent contingency 



$22,500 



Gabion (Coverage 100 feet X 54 feet = 5,400 square feet) 



Gabion mat 12 feet X 3 feet X 1 foot (36 square feet each) 



each 



150 



$24.00 



$ 3,600 



Cobble fill (2.1 tons each Gabion) 



tons 



315 



$ 3.30 



1,040 



Filter cloth 



square feet 



5,400 



$ 0.15 



810 



Installation 



square feet 



5,400 



$ 1.00 



5,400 



Subtotal 



$10,850 



Total cost including 25-percent contingency 



$13,600 



Lok-Gard blocks (Coverage 100 feet X 71 feet = 7,100 square feet) 



Lok-Gard blocks (1.38 square feet each) 



each 



5,154 



$ 1.25 



$ 6,440 



Gravel bedding (1 foot thick) 



tons 



420 



$ 3.50 



1,470 



Filter cloth 



square feet 



7,100 



$ 0.15 



1,060 



Installation 



square feet 



7,100 



$ 1.00 



7,100 



Subtotal 



$16,070 



Total cost including 25-percent contingency 



$20,100 



Tires (Coverage 100 feet X 60 feet = 6,000 square feet) 



Tires 



each 



1,480 



free 







Bolts with washers 



each 



4,440 



$ 0.50 



$ 2,200 



Cement 



pounds 



29,600 



$ 0.03 



890 



Filter cloth 



square feet 



6,000 



$ 0.15 



900 



Installation 



square feet 



6,000 



$ 1.00 



6,000 



Subtotal 



$ 9,990 



Total cost including 25-percent contingency 



$12,500 



18 



