used for supplying building materials, would be retained on a 

 stand-by basis to insure a ST?)ply of repair materials. 



b. Tiverton barrier . Operation of the barrier would involve 

 the closing of the sector gates, stoplogging of openings in the 

 dike, and patrolling the land side of the dikes. Personnel would 

 be maintained on a stand-by basis for these operations and periodic 

 maintenance . 



F-22. COST ESTIMATES 



The cost estimates for the Lower Bay barriers are based on 

 the plan as recommended and with assumed favorable foiuidation 

 conditions at the East barrier for the minimum amount and on less 

 favorable foundation conditions at the East barrier for the maxi- 

 mum amount. 



Details of the estimated minimum first costs of the Lower Bay 

 barriers, based T:pon the recommended plan, assuming a foundation 

 settlement of eight feet in the West barrier and a settlement of 

 20 feet in the East barrier, are given in Table F-5. Estimated 

 minimum annual charges are given in Table F-6. 



Details of the estimated maximum costs due to a 50-foot settle- 

 ment of the East barrier and to the addition of gates in the West 

 barrier are shown in Table F-7. Estimated maximum annual charges 

 are detailed in Table F-8. 



F-23. ALTERNATIVE SITES 



a. General . Several alternative sites were studied in detail 

 for the location of protective barriers throughout Narragansett 

 Bay. A brief discussion of these sites is given below: 



(1) South Street barrier . This site, just north of the 

 Fox Point location, was studied and a barrier similar to that at 

 Fox Point was considered. The small amount of savings in the cost 

 of the struct\ire over the Fox Point barrier when cosapsred with 

 the benefits ruled it out in favor of the Fox Point location. 



(2) Fields Point barrier . A barrier made xtp of rock 

 fill and earth fill sections with a large punping station 

 (30,000 c.f .s.) was considered. It would also have two gated 

 navigation openings. The high cost of punping made this site 

 marginal. Buildup ruled the site out. 



F-17 



