For Shinnecock, assume the following: 



NOD = 25 1 total days - 7 holidays - 64 weekend days = 1 80 days 



HD = 8 hours 



RR = 0.12 



PB = 0.15 



ALM = 0.03 



RMP = 0.10 



Therefore, at Shinnecock Inlet: 



EOT = (180 x8)[1.00- (0.12 + 0.15 + 0.03 + 0.10)] = 864 hr/year (7b) 



The PB, ALM, and RMP correction factors to some extent account for weather delays. But 

 because no equipment is in the water, delays due to weather should be minimal. In fact, at Indian 

 River Inlet, storm conditions are the preferred operating condition because of the increased 

 transport being fed to the fillet. If the plant did not operate during storms, large quantities of drift 

 would not be captured and thus lost to bypassing. Also, because no equipment is in the water, 

 there should be no impact to normal navigation use (boating or dredging). 



The target system capacity (the design operating rate in cubic meters per hour or cubic yards 

 per hour) can thus be calculated as 1 16 mVhr (152 ydVhr) (100,000 m 3 /year + 864 hr/year). 

 However, for flexibility to bypass larger quantities if needed, the design capacity should be 150 

 mVhr (196 ydVhr), which equates to 129,600 mVyear (170,000 ydVyear). Additional capacity 

 can be attained by increasing the number of hours worked in a day, increasing the number of days 

 worked in a week, or expanding the operating time beyond the Labor Day to Memorial Day 

 period. 



A cost analysis for this alternative includes the cost to purchase each element as well as labor 

 to operate the plant for a year. The equipment purchase cost (analogous to a mob/demob cost for 

 floating plant) is amortized over a project life of 30 years using an interest rate of 7-3/8 percent. 

 The estimate is based on similar costs of construction and operation for the Indian 

 River Inlet bypass plant from HQUSACE (1991) and Delaware Department of Natural Resources 

 and Environmental Control (Appendix G). At the time of this investigation (1997), construction 

 costs (Table 15) were determined by comparing cost indices from 1983 and 1989 to 1997 as 

 listed in Engineer Manual 1 1 10-2-1304 (HQUSACE 1996). 



Chapter 5 Bypassing Alternatives 59 



