(3) Provide openings large enough to prevent adverse 

 effects on water quality, marine life and normal uses of the baor. 

 In the preliminary design navigation openings were selected as 

 follows : 



East barrier: 50-foot depth and 1000-foot width 

 at mean low water. 



West barrier: UO-foot depth and UOO-foot width 

 at mean low water with 1 on 1,5 

 side slopes. 



Tiverton barrier: 30-foot depth and 100-foot 



width at mean low water; closed 

 during a hurricane by a pair 

 of sector gates. 



With the selected navigation openings, model tests, adjusted 

 for wind effects, show that the design flood wotild rise to eleva- 

 tions of U.Q feet above mean sea level at Newport and 8.9 feet above 

 mean sea level at Providence. Substantially con^jlete protection 

 would be obtained for a flood equal to or less than the tidal flood 

 of September 1938 • Model tests were made for various other sizes of 

 openings. Thus it was determined that the largest opening which 

 would give effective protection is about 60,000 square feet (see 

 paragraph 62). Although such openings meet the needs of commercial 

 vessels, larger openings are desired for Naval vessels, as discussed 

 in paragraph 7U* If the navigation opening in the East barrier is 

 increased to 1,500 feet by 60 feet, the design flood as reduced by 

 the barriers would rise to an elevation of 7*3 feet above mean sea 

 level at Newport and 11.3 feet above mean sea level at Providence; 

 substantial damages would result from both the design flood and a 

 flood of the 1938 magnitude. 



The only possible means of providing the large openings 

 required for naval use, and yet obtaining effective protection, 

 are through the use of gates. Gates to close openings 1*00 feet 

 or more in width and over 60 feet in depth are without precedent. 

 Detailed design studies and model tests would be required before 

 recommending such construction. Operation and maintenance of 

 gates ejcposed to a tidal s\irge of 13 feet and ocean waves of 2$ 

 feet would be very costly. 



59. LANDS, RIGHTS-OF-WAY AND RELOCATIONS 



Access to the site of the Fox Point barrier presents no 

 serious problem. Rights-of-waor would be necessary, but materials 

 could be obtained from existing soxirces, and relocations wDtG.d 

 be relatively slight. 



I48 



