c, West barrier . 



(1) Descrlptlcp . This stnictare, 7,100 feet long, 

 of the saaie general type as the East barrier, would cross the 

 Vfest Passage about 600 feet south of the Jamestonn Bridge (see 

 Plate 6), A navigation opening UOO feet vide and UO feet deep 

 at Jiean low water would be centered on the existing ship channel, 

 which passes between the two main piers of the bridge. Alterna- 

 tive sites as far south as Bonnet Shores were considered, as 

 discussed in Appendix F, 



(2) Geology . The West Passage site crosses a pre- 

 glacial depression whose depth is not known but may approach 

 UOO feet west of the ship channel. Materials in the depression 

 are fine-grained below an elevation of UO feet beiow m.s.l. 

 and somewhat coarser above, presenting moderately favorable 

 foundation conditions for the barrier. A rock foundation for 

 gates exists beneath the center of the ship channel at an 

 elevation of 80 feet below m.s.l, (see Appendix E). 



(3) Design . The West barrier design would be sub- 

 stantially the same as for the East barrier with regard to 

 grades, slopes, and cross-section, althou^ the wave action 

 may be a little less severe at this site, 



d, Land wall . 



The highway across Round Swamp on Conanicut Island 

 would be raised to 22 feet above mean sea level and protected 

 by stone facings on the slopes to prevent flooding across the 

 Island. 



e, Tiverton barrier . 



(1) Description . This structure would consist of an 

 earth-and-rock fill dike along the shorelines of the Island Park 

 and Tiverton areas at the head of the Sakonnet River, and a 

 crossing at the Old Stone Bridge between Island Park and Tiverton 

 (see KLate 7). The total length would be 9,U25 feet, of which 

 about 1,200 feet would lie between the existing bridge abutments 

 In the river, A navigation opening 100 feet wide and 30 feet 

 deep, referred to mean low water, would be provided which would 

 be closed during hurricanes by a pair of sector gates. The 

 existing to^m beaches would be maintained on the seaward side of 

 the dikes, with access ramps provided. 



U5 



