c. Design 



(1) Layout . Various alignments of the Fox Point barrier 

 were considered. The proposed plan would fit the existing condi- 

 tions best, would cause the least disruption to the operations of 

 the Narragansett Electric Ccanpany, and would tie in best with any 

 proposed futtire wharfage or highway use. A layout m.th the pump- 

 ing station on the west end of the barrier was considered, but 

 the proposed laj^'out would provide much better access to the site, 

 both for construction and for maintenance, and would be more 

 economical to construct (see Appendix F). 



(2) Construction materials . Several different tj^pes 

 of construction were considered, and a detailed design and cost 

 comparison was made between the proposed concrete gravity section 

 and an earth-and-rock-fill section. The concrete section was 

 slightly superior from the viewpoint of economy, engineering 

 simplicity, and adaptability for future use, 



(3) Grades. The 1938 hurricane flood level at Provi- 

 dence has been measured at 15.7 feet above mean sea level. The 

 design flood would be three feet higher. The design of the 

 barrier, with deck for wharfage or highway use at 12,5 feet above 

 mean sea level, and backwall at elevation 22,5 allows for 3.8 

 feet of freeboard. 



(U) Pumping capacity . The pumping station would con- 

 tain five large pumps having a combined capacity of 8,000 cubic 

 feet per second at a differential head of 22 feet. With a design 

 hurricane surge and a flood runoff of this amount, the pumps 

 could therefore draw the pool down to an elevation of about three 

 feet below mean sea level. In case of the improbable combination 

 of a full flood runoff of 9,200 cubic feet per second in the river 

 and a design tidal stirge in the bay, the pumps could discharge the 

 full runoff by reducing the differential head. This would be 

 accomplished by allovring the fresh water pool to rise to an eleva- 

 tion of three feet above mean sea level, a stage well below damage 

 level and little above the mean hirh T^jater line. At the time of 

 a hurricane surge, both the sluice urates and the cooling water 

 intake throurrh the barrier would be closed. The cooling water 

 would be taken from and later discharged into "t^e fresh water pool, 

 without increasing the pumping requirements. 



U3 



