Site: 



DALE HOLLOW LAKE 



Installation: The breakwater is moored by two anchors located at the extreme 

 ends of the structure. Each anchor is a 55-gallon drum filled with con- 

 crete. The mooring lines are of wire rope and are 24.4 m (80.0 ft) in 

 length . 



Field Experience 



Operation: A host of problems are listed as infrequently occurring, but all 

 are considered minor problems of little consequence. These problems 

 include instability, structural failure, collision damage, interference 

 with boating traffic, inadequate buoyancy, anchoring system failure, 

 mooring- line failure, coupling failure, and litter entrapment. Under 

 typical storm conditions with waves 0.5 m (1.5 ft) in height and 9.0 m 

 (29.5 ft) in estimated length, the transmission coefficient is 0.50. 



Maintenance: Scheduled maintenance consists of periodically inspecting the FTB 

 and replacing broken bands. 



Cost: The total construction cost for this breakwater was $330. This figure 

 translates to a cost of $6.01/m 2 ($0.56/ft 2 ). Annual maintenance costs 

 are estimated to be $60, covering mostly labor. 



Benefits: The operator felt that the breakwater had a positive effect on 



boaters' comfort, adding that he now has much fewer maintenance problems 

 with his marina. He regarded the FTB as having a negative effect on 

 waterfront appearance. The operator also rated the breakwater as 

 providing high performance in suppressing waves, meeting design goals, and 

 satisfying his needs. Overall performance was rated high. 



Project Analysis: It is likely that the problem of coupling failure will 



increase in magnitude dramatically in the next 2 years. Under moderate 

 wave action, FTBs coupled with nylon strapping have been known to fail due 

 to the banding chafing, fraying, and finally failing. Because site 

 conditions are modest and maintenance includes checking the strapping, it 

 is possible that this problem can be sidestepped, but this is still 

 unlikely. In other respects, the project should fare well since the site 

 is relatively tame. 



