38 



paragraph U5. The locations of the structures of these plans are shown 

 on fig. 15 J the details of the West Passage and East Passage navigation 

 openings of plan 30 are shown on fig. 17 and those of the other plans 

 are shown on fig. I8. The navigation opening in the Sakonnet River bar- 

 rier was similar to that of plan 29 (opening 100 ft wide by 30 ft deep); 

 however, this opening was completely closed for all tests of plans 30 

 through 3^- 



57- In plan 30^ the first plan including the Fox Point and Lower 

 Bay barriers, the Lower Bay barriers and navigation openings were iden- 

 tical with those of plan 29- The astronomical tide test of plan 30 was 

 made for conditions of the normal spring tide range of ^.1 ft at Newport, 

 and hurricane tide tests were made for this tide in combination with the 

 1938 hurricane tide and the 20-knot design hurricane tide. The effects 

 of plan 30 on astronomical tide ranges and elevations and on hurricane 

 tide elevations, and its effects on times of high water for both astro- 

 nomical and hurricane tides are shown in tables h and 3^ respectively. 

 The effects of this plan on both astronomical and hurricane tides 

 throughout the bay system were almost identical with those of plan 29 

 described previously. Astronomical tide ranges at gages located up- 

 stream from the Lower Bay barriers were reduced by an average of about 

 23 per cent, and hurricane tide elevations at Providence were lowered 

 from +15.1 ft to +7'9 ft mlw for conditions of the 1938 hurricane tide 

 and from +I7.2 ft to +9-1 ft for conditions of the 20-knot design hur- 

 ricane tide. Wo current velocity measurements were made in the naviga- 

 tion openings of plan 30- 



58. The locations of the barriers in the other plans of this series 

 (31 through 3^) were identical with those of plan 30^ the only difference 

 between plans in this series being the arrangement and size of navigation 

 openings in the East and West Passages (see fig. I8). The combined areas 

 of the East and West Passage navigation openings for this series of plans, 

 measured at approximately mean-tide level at We^vport (+2.0 ft mlw), were 

 as follows: 104,7C0 sq ft for plan 33; 9^,300 sq ft for plan 32; 73,500 

 sq ft for plan 3I; and 71^0^0 sq ft for plan 3^- The comparable area for 

 plan 30 was 83,900 sq ft. The model test conditions (astronomical and 



