F-19. AVAILABLE I'iAIERIALS 



Adequate unopened quarry sites are available for stpplying 

 derrick stone and quarry nin rock for the Lower B^ barriers. 

 Sand and gravel are available in sufficient quantities to pro- 

 vide the fill under the Fox Point barrier gravity section (see 

 Appendix E). 



F-20. PLAN OF CONSTRUCTION 



The structures in the Lower Bay barriers would require 

 about 3 years to construct, assuming good foundation conditions, 

 axKi k years with unfavorable foundations. The construction 

 schedule for each of the structures would be as follows: 



a. East barrier . Before construction can be initiated on 

 the East barrier, a more con^slete investigation of the foundaticn 

 must be made. The first constniction items would include the 

 opening of quarry sites, access roads, and loading facilities. 

 Placement of rock by floating equipment would be continuous 

 through the 3 or U-year construction period. 



b. West barrier . The procedure for construction of the 

 West barrier would be similar to that of the East barrier. 



c. Tiverton barrier . Construction of the Tiverton barrier 

 is based on dredging of the Portsmouth-Tiverton Channel, coffer- 

 damming for the gate structure and appurtenances, placement of 

 the rock and earth dikes, and building the access roads. 



(1) During the first year, the channel would be dredged, 

 the cofferdam and the concrete for the gate structures placed, and 

 the barrier constructed across the channel. 



(2) Completion of the gate structure, removal of coffer- 

 dam, installation of gates and equipment would be accoii?)lished 

 during the second year or early in the third year. 



(3) Land dikes, access roads, and appurtenant works 

 would be constructed concurrently with the barrier and the naviga- 

 tion gates. 



F-21. OPERATION AND MAINTMANCE 



a. East and West barriers . The barrier would require periodic 

 maintenance in order that no disintegration of the structure should 

 occur and navigation aids would be properly maintained. Quarry sites, 



F-16 



