MN VU\ HURRICANE SURVEY INTERIM! |REPORT NARRAGANSETT BAY AREA RHODE ISLAND MASSACHUSETTS New England Division - Boston, Mass. I5 FEBRUARY 1957 E ¢2b?9€00 TOEO go ACEO AO 1OHM/TaiN CORPS (OF ENGINEERS, 0.3. ARMY OFFICE OF THE DIVISION ENCINEER: NEw ENGLAND DIVISION LSU Causeway Street soston 14, Mass. NEDGW 21 Macch 1957 SUBJECT: Interim Rapert, Hurricane Survey, Narrajansett Say Area, Rhode Island and Massachusetts Car =) Division Bagineer South Atlantic Division 336 Old Pest Office %ulldin. Atlanta 1, Georgia L. In compliance with iastcuctions from the Chief of Engineers, eight (S) copies of the Interim -..epori, turricane Swvey, Narragansett Say Area, Rhode Island and Massachusetts, prepaved vy this aftice, are inclosed under separate cever. 2. The report has becn prepared pursuant to the authorization contained in Public Lew 71, c&ch iengress, and is one cf @ series of ceports which, when completed, wiil coastitute a survey of uc coasia: area of New England subject to hurricane tidal floodaii.z. 3. As the ceport has not yet »¢en approved by the Chief of Engineers, the contents are not for prslic release. FOR THE DIVISION ENGINEER: : 1 Incl. MILES L. WACHENDOUT Rpt, Narra ‘ay, Lt. Col., Corps of “agineers w/Appendices and Executive Officer d4ES Supplement (Copies 36 thru 43) (tinder separate cover) i i% al wi a ohh, v1 ie We ey POE irri, ay 7 i Ment a - v= - “he as asa a oie q rf ¢ “a I ae vi f wo P Paras : H FF ne i Be a “ ‘ : Wisk. oh j a te Ah oA bs bot " 7. 1 ’ \ f L] 4 i i 7 0 Te Ga ey vi Pree, (at vie + ‘n ee Po gee Doh x : rm On a ve satan iaaaeest is "asia an : Ga HC: enti Re rk mE At | JOSRSVRO Livan Pie : 38 t3e «4 Op Pedy nea ; ¥ » ae fe | eae | ao 4a ; ye? qe 21ebokga eres ices | pee — thems aaa, wine ak 4 é , welede id Jet a jut echeen ror5 Aly wey hs oe y Bini me wt writ \eiabeos Sess Pade ) tote e at “be Tyrone Le ge. aT TS) amy 5 a pero es se INTERIM! |REPORT NARRAGANSETT BAY AREA RHODE ISLAND MASSACHUSETTS Corps of Engineers, U.S. Army - Office of the Division Engineer New England Division - Boston, Mass. I5 FEBRUARY 1957 Oe (0) fll 0 Paragraph WE WwW po ~“ Oo 10 11 TABLE OF CONTENTS Title GLOSSARY SYLLABUS AUTHORITY SCOPE OF SURVEY General Engineering Studies Special Studies Coordination PRIOR REPORTS Hurricane Reports Navigation Reports DESCRIPTION Location and Extent Tributaries and Harbors Tides and Currents General Geology and Topography a. Structure b. The Rocks of Narragansett Ray c. The Sediments of Narragansett Bay d. Topography Area Maps ECONOMIC DEVELOPMENT Population Industry Fisheries Agriculture Navigation Transportation Recreation Defense Establishments Page Www (wy ™ A oOo © VIVVIIWASH Paragraph 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Title CLIMATOLOGY Climate Temperature Precipitation HURRICANE TIDAL FLOODS OF RECORD Historical Hurricanes Recent Hurricanes Hurricane Frequency HURRICANE CHARACTERISTICS General Description Origins and Tracks Winds and Barometric Pressure Rainfall Waves Tidal Surges DESIGN OF HURRICANE TIDAL FLOOD Analysis of the Hurricane Surge Wind Field and Barometric Pressure Astronomical Tide and Tidal Flooding Storm Tracks Selection of Design Hurricane Tidal Flood Design Hurricane Flood Levels Design Waves and Wave Run-Up Stream Flow Coincident with Hurri- cane Tidal Flooding Design Stream Flow il 13 13 13 14 14 15 17 17 17 18 18 19 20 20 21 22 (ala, 23 23 23 24 EXTENT AND CHARACTER OF THE FLOOD AREA 26 Paragraph 43 44 45 46 47 48 49 50 5 aya Title HURRICANE TIDAL FLOOD DAMAGES Experienced Damages Recurring Damages Average Annual Losses Scare Costs EXISTING CORPS OF ENGINEER'S PROJECTS IMPROVEMENTS DESIRED Views of Local Interests Proposals for Protection a. Upper Providence River Barrier Plans b. Lower Providence River Plans c. Greenwich Bay Plans d. Lower Narragansett Bay Barriers e. Series of Subsurface Barriers f. Sakonnet River Barriers g. Local Protective Measures Public Hearings HURRICANE FLOOD PROBLEMS AND SOLUTIONS Hurricane Flood Damages Possible Protective Measures Con- sidered for Narragansett Bay a. Hurricane Warning and Emergency Flood Mobili- zation Measures b. Revision of Zoning Regulations and Building Codes c. Local Protection (1) Individual Measures (2) Protection Against Flooding by Local Barriers, Dikes and Walls iii 29 28) 30 30 30 31 oyh Sill 31 Sil 31 Sic 32 32 33 34 34 34 Paragraph 53 54 55 58 Title HURRICANE FLOOD PROBLEMS AND SOLUTIONS (Cont'd) d. (3) Protection Against Wave Action by Breakwaters (4) Protection Against Erosion by Low Walls and Bulkheads Large-scale Tidal Flood Barriers The Hurricane Flood Problem Studies of Alternative Barrier Plans ae b. Considerations Governing Selection of Barrier Sites (1) Navigational Requirements (2) Tidal Circulation and Fresh- water Discharge (3) Build-up (4) Local Wind and Wave Effects Alternative Plans of Protection (1) Lower Bay Barrier Plan (2) Middle Bay Barrier Plan (3) Fields Point Barrier Plan (4) Fox Point Barrier Plan Selection of a Plan of Protection ae b. Fox Point Barrier Lower Bay Barriers HURRICANE FLOOD CONTROL PLAN General Fox Point Barrier a. b. Ce General Description Geology Design (1) Layout (2) Construction materials (3) Grades (4) Pumping capacity Lower Bay Barriers a. b. General East Barrier iv Page Paragraph 59 60 61 62 63 (1) Description (2) Geology (3) Design c. West Barrier (1) Description (2) Geology (3) Design d, Land Wall e. Tiverton Barrier (1) Description (2) Geology (3) Design f. Hydraulic and Hydrologic Considerations g. Navigation Openings Lands, Rights-of-Way and Relocations Operation and Maintenance a. Fox Point Barrier b. Lower Bay Barriers Highway Crossings Utilizing Barriers a. Fox Point Barrier b. Lower Bay Barriers Degree of Protection a. Protection by Fox Point Barrier b. Protection by Lower Bay Barriers Effects of the Plan on Normal Conditions in Bay a. Fox Point Barrier b. Lower Bay Barriers (1) Basic studies (2) Tidal range and currents (3) Navigation (4) Temperature and salinity (5) Pollution and fisheries (6) Beach erosion Page HURRICANE FLOOD CONTROL PLAN (Cont'd) 44 44 44 45 45 45 45 45 45 45 46 46 46 47 48 49 49 49 49 49 50 50 50 50 52 Be 52 52 53 53 53 Sas 54 Paragraph Title Page HURRICANE FLOOD CONTROL PLAN (Cont'd) 64 Additional Studies of Lower Bay Barriers 54 a. Design Flood 54 b. Negotiations with the Navy 55 Cc. Model Tests and Analytical Studies 55 d. Foundation Investigations 55 e. Pollution 55 f. Fish and Wildlife 55 g. Design Studies 56 65 Views of Local Interests 56 66 ESTIMATES OF FIRST COST Sil 67 ESTIMATES OF ANNUAL CHARGES SY ESTIMATES OF BENEFITS 68 Evaluated Tangible Benefits 61 69 Unevaluated Tangible Benefits 63 70 Intangible Benefits 63 ECONOMIC JUSTIFICATION al Benefit-cost Comparison 64 2. PROPOSED LOCAL COOPERATION 64 aS APPORTIONMENT OF COSTS AMONG INTERESTS 66 74 COORDINATION WITH OTHER AGENCIES 67 a. Federal Agencies 67 b. State Agencies 68 c. Local Agencies 68 DISCUSSION ie The Problem 69 76 Solutions Considered 69 77 Selection of Plan 70 vi Paragraph Title DISCUSSION (Cont'd) a. Lower Bay Barriers b. Middle Bay Barriers c. Fields Point Barrier d. Fox Point Barrier 78 Costs and Benefits vy CONCLUSIONS 80 RECOMMENDATIONS vii Page 70 70 70 70 lal 72 73 “8? tins a2) vi soLeeu ray Cy CM MOR ARP LOD CONTROL Fiat (Cound ateis 78d Selb itio.t a) Py) yt ay be Cate NRRL es | ifd Lower Baye gtihchie ahlert a ay , 54 | ea = 6 Pane Fp 1b (et 54 , Gases ie eese tha Haney SSS ie . Medel Tors wat Maalytlem a Sapbhes ayoratheeo ovis he Pyoestion [ycukh eee ya 7 vo e, IV MOON om > y Ben Re Vi iiitite ae | ite Nee Yee ir ee 7 nO La sal ket @) Gti ’ 56 RA PULA I peli a a ee ee i Punt Kl y wi oF ay : "i it us “7 ma " . Coe MATEN de ken rere ri Fi Pumioate A Y & wollte ay Cnevaleet: (pes Mekeiae ye WENN: ditt buat | i) " by ie aii ‘ We ; . a MT all | y wie ’ / 1 one ie Number FIGURES Title Population Distribution Paths of Tropical Storms of Hurricane Intensity Tracks of Selected Hurricanes Following Page 10 14 1/7 TABLES Population of Cities and Towns Hurricane Occurrences Design Wave Heights Reduced Flood Levels With Plan in Effect First Costs and Annual Charges Fox Point Barrier First Costs and Annual Charges, Lower Bay Barriers - Estimate of Minimum Cost First Costs and Annual Charges, Lower Bay Barriers - Estimate of Maximum Cest Recurring and Preventable Tidal Flood Damages Economic Data of Proposed Plan 59 60 62 64 PLATES Title General Plan Extent of Tidal Flooding and Damages. September 1938 Flood Fox Point Barrier Plan Fox Point Barrier Plan. Plan, Profile and Sections Lower Bay Barrier Plan. East Barrier. Conanicut Island to Newport Neck Lower Bay Barrier Plan. West Barrier. Plum Beach to Conanicut Island Lower Bay Barrier Plan. Tiverton Barrier. Portsmouth to Tiverton Narragansett Bay. Hurricane Flood Levels. September 1938 Flood Reduced by Fox Point and Lower Bay Barriers Mt. Hope Bay - Sakonnet River. Hurricane Flood Levels. September 1938 Flood Reduced by Lower Bay Barriers PHOTOGRAPHS Following Page Hydraulic model of Narragansett Bay constructed at Waterways Experiment Station, Vicksburg, Mississippi 3 Flood waters swept up the Providence River flooding industrial areas in Providence. Hurricane ''Carol'"', August 1954 6 Wave action at Bristol, Rhode Island. Hurricane "Carol", August 1954 19 Flood waters receding from center of business district in Providence. Hurricane ''Carol", August 1954 26 Flood damage at Conimicut Point, Warwick, Rhode Island. Hurricane of September 1938 27 Wreckage left in Providence by subsiding flood waters. Hurricane Carol", August 1954 28 Sandbagging of entrances to an electric generating station during a hurricane ''Scare" 28 Business district of Providence. Hurricane "Carol'', August 1954 34 Site of Fox Point Barrier 43 Site of East Barrier 44 Site of West Barrier 45 Site of Tiverton Barrier 46 Small boats wrecked at Barrington, Rhode Island. Hurricane of September 1938 63 Paragraph A-l A-2 1 — 1 0 WN i 0. 0 oaonNto ul pf BOWED now APPENDICES Title APPENDIX A - HISTORY OF HURRICANE TIDAL FLOODING HISTORICAL RESEARCH SUMMARY OF HURRICANE OCCURRENCES DESCRIPTION APPENDIX B - HURRICANE SURGES AND TIDAL HYDRAULICS NORMAL CONDITIONS IN NARRAGANSETT BAY General Astronomical Tides Factors Influencing Gravitational Tides Currents Temperature Salinity Flushing Silting Recording Tide Gages In Narragansett Bay Corps of Engineers' Tide Gage Program HURRICANE TIDAL FLOODING General Hurricane of September 21, 1938 Hurricane of September 14, 1944 Hurricane of August 31, 1954 Frequency of Tidal Flooding A-2 w 1 (as. He Dod wo How onww APPENDIX B (Cont'd) Paragraph Title Page DESIGN HURRICANE TIDAL F LOOD B-16 Wind Field B-20 B-17 Storm Surge at Mouth of Bay B-20 B-18 Storm Surge in Narragansett Bay B-21 B-19 Selection of Design Storm Surge B-21 B-20 Waves B-22 EFFECT OF BARRIERS ON TIDAL FLOODING B-21 General B-22 B-22 Description of Model B-23 B-23 Model Testing Program B-23 a. Middle Bay Barriers B-23 b. Lower Bay Barriers B-24 c. Field Point Barrier B-24 d. Fox Point Barrier B-24 B-24 Analytical Routings B-24 B-25 Wind Set-Up B-25 B-26 Ove rtopping B-26 B-27 Summary B-26 a. Fox Point Barrier B-27 b. Lower Bay Barriers B-27 (1) East Barrier B-27 (2) West Barrier B-27 (3) Tiverton Barrier B-27 EFFECT OF BARRIERS ON NORMAL CONDITIONS B-28 General B-28 B-29 Tides B-28 B-30 Currents B-28 B-31 Temperature B-29 B-32 Salinity B-29 B-33 Flushing B-29 Parag raph Title APPENDIX C - HYDROLOGY AND STREAM FLOW C-l Introduction C-2 Temperature and Precipitation C-3 Runoff and Stream Flow C-4 Hurricane Rainfall C-5 Hurricane Runoff a. September 1938 Flood b. September 11, 1954 Flood (Edna) c. August 19, 1955 Flood (Diane) -6 Design Storm 7 Design Flood for Fox Point Barrier a. Woonasquatucket River b. Moshassuck River C-8 Design Flood for Lower Bay Barriers a. Blackstone River b. Woonasquatucket and Moshassuck Rivers c. Pawtuxet River d. Taunton River C-9 Design Stream Flow a. Fox Point Barrier b. Lower Bay Barriers APPENDIX D - FLOOD LOSSES AND BENEFITS D-1 Measurement of Flood Damages a. Damage Surveys b. Loss Classification D-2 Experienced Damages a. Tidal-Flood Losses b. Providence, Rhode Island c. West Side: Narragansett Bay d. East Side: Narragansett Bay and Mount Hope Bay D-3 Recurring Damages a. General b. Evaluation of Individual Flood- Protection Measures c. Normal Recovery d. Normal Growth Page Ce eh a ag Se YVIVYMNHUNMKNUHO A ANKE AAIAAAAAAA GaGa ea 1 i] i oP DOD @ QO OOO) © 1 So} (9) to) la) Io Io I Conta ROR On eae GUD aaa Paragraph D-4 1 anon fp WD KH bit es ey te in to E-9 E-10 E-ll E-12 E-13 E-14 E-15 E-16 APPENDIX D (Cont'd) Title Annual Losses and Benefits a. General b. Average Annual Losses c. Average Annual Flood-Prevention Benefits d. Scare Cost Benefits APPENDIX E - GEOLOGY AND FOUNDATION DATA PART I - NARRAGANSETT BAY Physiography and Geology Subsurface Investigations General Foundation Conditions Geology of the Fox Point Site Geology of the East Barrier Site Geology of the West Barrier Site Availability of Quarry Stone Availability of Concrete Aggregates a. Fox Point Site b. Lower Bay Site Conclusions and Recommendations a. Foundation Explorations (1) Fox Point (2) West Barrier (3) East Barrier b. Quarry Development c. Inherent Physical Geological Changes PART Il - SAKONNET RIVER Physiography and Geology Subsurface Investigations Geology of the Tiverton Site Availability of Quarry Stone Availability of Concrete Aggregates Availability of Earthen Borrow Conclusions and Recommendations 1ppsetpepep bp bb te t 8 b dd NUS AAKAOCUUA hWNNN SR SIS Sok So ol eS HRA Ee oF DoMDMDOIA Paragraph F-10 F-11 F-12 F-13 F-14 APPENDIX F - DESIGN STUDIES AND COST ESTIMATES Title INTRODUCTION SURVEYS AND EXPLORATIONS DESIGN CRITERIA BASIS OF COST ESTIMATES Cost Estimates Unit Prices Contingencies, Engineering and Overhead Annual Charges FOX POINT BARRIER Description and Pertinent Data a. b. Cc. d. e. f. g. General Barrier Sluice Gate Structure Cooling Water Intake Structure Pumping Station Land Walls Pertinent Data Design ae b, Cc. d, e. f. g. General Barrier Sluice Gate Structure Cooling Water Intake Structure Pumping Station Foundations Land Walls Modifications to Sewers and Drainage Lands and Damages Plan of Construction Operation and Maintenance Cost Estimates a) ea) 5) a) ) FS) a] a) es) a] al tea To] Ye) 1) Co) Us) es) a] Pa NAOTODDOUN UNUM Oh AB WW WW Ww Paragraph F-15 APPENDIX F - DESIGN STUDIES AND COST ESTIMATES (Cont'd) Title Alternative Plans for Fox Point aXe b. Ge d. e. f. General Alignment No, 1 Alignment No, 2 Rock and Earth Fill Barriers Concrete Barriers Control of Level of Providence River LOWER BAY BARRIERS East Barrier a. b. Description and Pertinent Data Lands and Damages West Barrier ae b. Description and Pertinent Data Lands and Damages Tiverton Barrier a. b. Description and Pertinent Data Lands and Damages Available Materials Plan of Construction a. b. Ce. East Barrier West Barrier Tiverton Barrier Operation and Maintenance ae b. East and West Barrier Tiverton Barrier Cost Estimates Alternative Sites a. General (1) South Street Barrier (2) Fields Point Barrier (3) Conimicut Point Barrier (4) Middle Bay Barrier (5) Sakonnet River Barriers Paragraph a0 -1 -2 -3 APPENDIX G - PUBLIC HEARINGS General Digest of Public Hearings Letter of Comment a. Letters of Comment on Pollution Ce Letters of Comment by Fish and Wildlife Service a. b. Local Cooperation ae b. Ce. AND VIEWS OF OTHER AGENCIES Es iy) @ en | — — — Rhode Island Hurricane Survey Advisory Committee tot = = U.S, Public Health Service Rhode Island Public Health Service Massachusetts Department of Public Health L} _ I NN U.S. Fish and Wildlife Service Massachusetts Division of Marine Fisheries { i) The Honorable Dennis J, Roberts, Governor, State of Rhode Island Governor, Commonwealth of Massachusetts The Honorable Walter H. Reynolds, Mayor of Providence G-2 a) 0) aa (2) (@) 0) OO O(N) () (6) @) Ly) mw t te No. A-1 APPENDICES - TABLES Title History of Hurricane Tidal Flooding, Narragansett Bay Area Summary of Other Notable Storms that Caused High Tides Astronomical Tides, Narragansett Bay Temperature and Salinity Observations by Narragansett Marine Laboratory Tide Gages - Recording and Non-Recording Pertinent Data on Recent Hurricanes - Hurri- canes since September 1938 Hurricanes or Severe Storms - Narragansett Bay Area Elevation - Frequency Data - Hurricanes or Severe Storms at Provid2nce, Rhode Island Effect of Barriers on September 1938 Hurri- cane and Design Tidal Floods Flushing Rates Temperature and Precipitation at Providence, Rhode Island (1904-1954) Streamflow Data at U.S.G.S, Gaging Stations, Narragansett Bay Area Hurricane Rainfall Summary of Hydrologic Data No. D-1 APPENDICES - TABLES (Cont'd) Title Page Description of Damage Areas, Narragansett Bay D-4 Experienced 1954 Hurricane Tidal Flood Losses by Area and Type, Narrangasett Bay, Massa- chusetts - Rhode Island D-5 Experienced 1954 Hurricane Tidal Flood Losses by Town and Type, Narragansett Bay, Massa- chusetts - Rhode Island D-6 Description of Damage Areas Used for Economic Analyses D-14 Recurring Tidal Flood Losses - Major Hurricanes and Other Storms During Past 50 Years D-15 Design Criteria and Selected Top Elevations F-2 Pertinent Data - Fox Point Barrier F-4 Estimated First Costs for Fox Point Barrier F-8 Estimated Annual Charges - Fox Point Barrier F-11 Estimated First Costs - Minimum Amourt Lower Bay Barriers F-19 Estimated Annual Charges - Minimum Amount Lower Bay Barriers F-21 Estimated First Costs - Maximum Amount Lower Bay Barriers F-22 Estimated Annual Charges - Maximum Amount Lower Bay Barriers F-23 APPENDICES - PLATES B-1 Tide Curves - Hurricane of 21 September 1938 B-2 Tide Curves - Hurricane of 14-15 September 1944 B-3 Tide Curves - Hurricane of 31 August 1954 B-4 Tidal Elevations at Providence B-5 Frequency of Tidal Flooding from Hurricanes and Storms at Providence, Rhode Island B-6 Hurricane Flood Levels - East shore of Narragansett Bay B-7 Hurricane Flood Levels - Sakonnet River, Mount Hope Bay, and Taunton River from Sakonnet Point to Dighton, Massachusetts B-8 Effect of Proposed Plan on Design and 1938 Hurricane Tidal Elevations C-1 Drainage Basin Map C-2 Isohyetal Map, Storm of September 17-22, 1938 C-3 Depth-duration Curve, Design Storm for Fox Point Barrier C-4 Depth-duration Curve, Design Storm for Lower Bay Barriers C-5 Discharge Hydrographs from Transposed September 1938 Rainfall at Fox Point Barrier C-6 Discharge Hydrographs from Transposed September 1938 Rainfall at Lower Bay Barriers APPENDICES - PLATES (Cont'd) Title Data for Economic Analysis, Damage Zone 4b Geology, Geology, Geology, Geology, Geology, Geology, Geology, South Street and Fox Point Sites Fields Point Site Conimicut Point to Nayatt Point Site Middle Bay Site Lower Bay-East Barrier Site, Sheet 1 of 3 Lower Bay-West Barrier Site, Sheet 2 of 3 Lower Bay-Tiverton Barrier Site, Sheet 3 of 3 Tidal Barrier Studies - General Plan APPENDICES - axci3IT No. Title B-1l Protection of Narragansett Bay from Hurricane Tides: Interim Report on Hydraulic Model Investigations To Accompany Appendix B GLOSSARY HURRICANE SURGE: the mass of water causing an increase in elevation of the water surface above predicted astronomical tide at the time of a hurricane; it includes wind set-up; sometimes the maximum increase in elevation is referred to as the surge. HURRICANE TIDE: the rise and fall of the water surface C1+ring a hurricane, exclusive of wave action, KNOT: a velocity equal to one nautical mile (6080. 2 ft.) per hour (about 1. 15 statute miles per hour). OVERTOPPING: that portion of the wave runup which goes over the top of a protective structure. PONDING: the storage of water behind a dike or wall from local runoff and/or overtopping by waves. POOL BUILDUP: the increase in elevation of water surface be- hind a structure due to runoff and/or overtopping by waves, RUNUP: the rush of water up the face of a structure on the breaking of a wave. The height of runup is measured from the still-water level. SIGNIFICANT WAVE: a statistical term denoting waves with the average height and period of the one-third highest waves of a given wave train. SPRING TIDE: a tide that occurs at or near the time of new and full moon and which rises highest and falls lowest from the mean level, STILL WATER LEVEL: the elevation of the water surface if all wave action were to cease, STORM SURGE: same as "hurricane surge," GLOSSARY (Cont'd) WAVE HEIGHT: the vertical distance between the crest and preceding trough. WAVE TRAIN: a series of waves from the same direction. WIND SET-UP: the vertical rise in the stillwater level on the leeward side of a body of water caused by wind stresses on the surface of the water. BUILDUP BELOW BARRIER: the increase in water surface ele- vation in feet immediately downstream from the barrier re- sulting from construction of the barrier. SYLLABUS The Division Engineer finds that a serious problem of hurri- cane tidal flooding exists in the densely populated Narragansett Bay area. The acuteness of this problem is indicated by the fact that tidal flood damages in the area in 1954 totalled $92, 000, 000. A recurrence of the hurricane tidal flooding that has been experi- enced in the past twenty years would cause damages totalling ap- proximately $220,000,000 at 1956 price levels. He concludes that protective barriers in Narragansett Bay are economically justified. The Division Engineer recommends a two-unit solution of the problem: a. For the protection of the City of Providence, Rhode Island, the immediate construction of a concrete barrier and pumping station across the Providence River at Fox Point in Providence, The estimated cost is approximately $16,500,000 at present day prices. b. For the general protection of Narragansett Bay, the con- struction of rock-fill barriers across the East and West Passages in Lower Narragansett Bay and a barrier across the Sakonnet SYLLABUS (Cont'd) River at Tiverton, subject to more detailed design studies of the structures and their effects on navigation, pollution and fisheries. The estimated cost of these barriers, based on optimum founda- tion conditions, is $69,000,000. Some revision of this estimated cost may be expected upon completion of the detailed design studies which the Division Engineer recommends. Under the most unfavorable foundation conditions the estimated cost of these barriers is $109, 000, 000. U.S. ARMY ENGINEER DIVISION, NEW ENGLAND CORPS OF ENGINEERS 150 Causeway Street Boston 14, Masse NEDGW 15 February 1957 SUBJECT: Interim Report on Hurricane Survey, Narragansett Bay, Rhode Island and Massachusetts TO: Chief of Engineers Department of the Army Washington 25, D.C. ATTOITLON: ENGW AUTHORITY 1. This report is submitted in partial compliance with authorization contained in Public Law 71, 8th Congress, lst session, adopted 15 June 1955, which reads: "Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled. That in view of the severe damage to the coastal and tidal areas of the eastern and southern United States from the occurrence of hurricanes, particularly the hurricanes of August 31, 195, and September 11, 1954, in the New England, New York, and New Jersey coastal and tidal areas, and the hurricane of October 15, 195, in: the coastal and tidal areas extending south to South Carolina, and in view of the damages caused by other hurricanes in the past, the Secretary of the Army, in cooperation with the Secretary of Commerce and other Federal agencies concerned with hurricanes, is hereby authorized and directed/to cause an examination and survey to be made of the eastern and southern seaboard of the United States with respect to hurricanes, with particular refer- ence to areas where severe damages have occurred. SEC. 2. Such survey, to be made under the direction of the Chief of Mmgineers, shall include the securing of data on the behavior and frequency of hurricanes, and the determination of methods of forecasting their paths and improving warning services, and of possible means of preventing loss of human lives and damages to progerty, with due consideration of the economics of proposed breakwaters, seawalls, dikes, dams, and other structures, warning services, or other measures which might be reouired." SCOPE OF SURVEY 2. GENERAL This interim report of survey scope comprises the results of an examination and survey of hurricane tidal flooding in the Narragansett and Mount Hope Bay areas of Rhode Island and ifassachusetts. It is one report of a series in preparation which, when completed, will constitute a full survey of the coastal areas of New ingland subject to tidal flooding from hurricanes. In the preparation of this report, extensive basic data was collected and analyzed because of the limited information available on hurricane tidal flooding when the survey was initiated. All available data on tidal hydraulics, hurricane characteristics, past hurricanes in the area, and the oceanography of Narragansett Bay were utilized. Various engineering and special studies were carried out, and work was coordinated with various Federal, state and local agencies. 3. ENGIN#sRING STUDIES Detailed hydrographic surveys were made as a basis for analytical and experimental studies of protective works in Narragansett Bay, both for hurricane tide and normal tide conditions. Field investigations were made of tidal flood damages in the entire survey area. Field investigations also included topograrhic surveys, soundings and borings for each of the barrier sites investigated, except that in the deep waters of the Lower Bay seismic investigations of foundation conditions were made instead of borings. All of the many plans of protection proposed by iriterested parties were considered in order to determine the most practical and economical means of protection against tidal flooding. The more suitable plans were thoroughly investigated, and designs and estimates of costs and benefits prepared. lh. SPECIAL STUDIES A hydraulic model of Narragansett Bay, 250 feet in length and 100 feet in width, at the Waterways Experiment Station in Vicksburg, Mississippi, was used to investigate the characteristics of normal and hurricane tides in the bay and the effectiveness of barriers in reducing hurricane flood levels. The Beach Erosion Board, assisted by the Texas A&M Research Foundation, using data on maximum hurricane wind velocities and durations obtained from the U.S. Weather Bureau, assisted in studies of a design hurricane flood. Limited ‘studies were made of the behavior and characteristics of hurricanes. Studies were made of wave action and the effect of barriers in the Lover Bay on navigation, pollution and fisheries. The Narragansett Marine Laboratory of the University of Rhode Island contributed to these studies. Se COORLLVATION This report has been prepared with the cooperation of various Federal, state and local agencies, who have assisted in furnishing information and advice in the solution of the many complicated problems of the survey. Fublic hearings were held at Providence, Newport and #all\ River to acquaint the people in the area with the results of the survey and to enable them to present their views thereon. Details of coordination with other agencies are described in paragraph 7h. PaiOn REPORTS 6. HURRICai eS REPORTS There are no previous reports by the Corps of Engineers specifically on the subject of hurricanes and hurricane protection in the Narragansett Bay area. Part II, Chapter XXXIX, of the un- published report of the New England-New York Inter-Agency Committee on "The Resources of the New mnsland-New York Region", prepared pursuant to a Presidential directive of October 9, 1950, contains a section devoted to hurricanes in the northeastern United States. The general nature and extent of damages caused in the region by the hurrican2s of September 21, 1933; September 1h, 19h); August 31, 195 (Carol); September 11, 195 (Edna) and October 16, 195) (Hazel) are discussed therein, together with the problems of establisning protective measures. 7. NAVIGATION AwPOx'lS Numerous reports have been prepared and submitted for the improvement of many of the channels and harbors in the Narragansett Bay area and others are in preparation. ae. Among the more recent reports, which have been the basis for authorized projects, are the following: Report Providence River and Harbor, R.I. Review Report: H.D. No. 173, 75th Congress, lst session. Wickford Harbor, RI. Survey report: S.D. No. 11, 79th Congress, 2nd session. Taunton Hiver, Mass. Survey report: H.D. No. 03, 7ist Congress, 2nd session; Survey Report: H.D. No. 196, 80th Congress, lst session. Sakonnet Harbor, R.I. Survey report: H.D. No. 36, 82nd Congress, 2nd session. Bullocks Point Cove, R.I. Survey report: H.D. No. 22, 83rd Congress, 2nd session. Project Dredging 35-foot approach channel from deep water in Narragansett Bay to Fox Point. Adopted August 26, 1937. Project completed in 1950. Construction of breakwaters and maintenance of channel. Approved 2), July 196. Project completed in 199. Channel 12 feet deep to Taunton Municipal wharf; a small craft anchorage 8 feet deep at Dighton; and turning basin 12 feet deep at Taunton. Adopted 3 July 1930 and 30 June 1948. Provides for extension of existing breakwater and dredging of harbor. Approved 3 September 195). Provides for breakwater and jetty, dredged channel and anchorage areaSe Authorized 3 September 195). b. Reports currently being prepared which consider various improvements within the Narragansett Bay area are the following: Newport Harbor, kel. Survey report: fiver and Harbor Act of 2) July 196. ‘Greenwich Cove, RI. Preliminary examination and survey: House Resolution, adopted 16 August 1950. ‘ Apponaug Cove, RI. Survey report: House resolution, adopted 27 June 1956. To determine feasibility of im- proving navigation by deepening part of waterfront channel and providing a small-boat basin. To determine possibilities for development of a small=-boat harbor. To determine possibilities for development of a small=-boat harbor. *S[@AZT POOTJ BUeDTAINY Jutonpetz ut srais -Ieq JO SSoUdAT}IATJa JY} pue Avg iJOSUeDEIICN UI SUOTJIPUOD [epl} JO SOTpNys ul TOO} e{qenytea e SEM [epoOW sy, “a.UeptAcCIg paeMmoy Aeq Jo YZNOW Wor YJI0U SuryooT ‘tddississtw ‘sinq ‘uolje1G yUoUITIedxgq sAeMI92}IEM 12 po2zONaZsuOD Avg }JOSUeDeIIEN JO [epoum II[ne1pAPy 1 1% <2 7 * oy b r z ~ a = bay 3 ay peck: \ pryecpeusbbs 2 *~ a WPEAE, OF 103 e Mery peheuset Wickford Harbor, k.I. Review report: House Resolution adopted 27 June 1956. To determine possibilities for further development of a small-boat harbor. c. Other navigation studies authorized within the Narragansett Bay area on which reports will be prepared are the following: Dutch Island Harbor, R.I. Preliminary examination: River and Harbor Act of 2) July 196. Pawtuxet Cove, R.I. Preliminary examination: House Resolution, adopted 5 April 199. Providence River and Harbor, R.I. Survey report: Senate Resolution, adopted 6 January 1950. intracoastal Waterway, R.I. Preliminary examination: Senate Resolution, adopted 13 April 1950. Bristol Harbor, R.I. Preliminary examination: House Resolution adopted 29 July 1955. Seekonk River, R.I. Survey report: Senate Resolution, adopted 6 January 1950. To determine possibilities for development of a small- boat harbor. To determine possibilities for development of a small- boat harbor. To determine teasibility of improving the harbor for commercial navigation. To determine possibilities for development of a navigable waterway, particularly through State of Rhode Island. To determine possibilities for development of a small- boat harbor. To determine feasibility of improving the river for commercial navigation. DESCRIFTION 8, LOCATION AND EXTENT The Narragansett Bay area includes about one-half of the totel area of Rhode Island, The bey and connecting tidal waters form a deep indentation in the Rhode Island coastline between Foint Judith on the west and Sakonnet Foint on the east, extending three-fourths of the length of the state in a northerly direction past Providence, the state capital (Flate 1). Mount Hope Bay, which extends northeast from Narragansett Bay proper into Massa- chusetts ten miles beyond the city of Fall River, and the Sakonnet River are considered part of Narragansett Bay for purposes of this report. To the south and southeast the bay lies directly exposed to the open ocean, making it vulnerable to the force of hurri- cane surges sweeping up the Atlantic coast. The shoreline is characteristically irregular and marked by numerous forelands, sandy beaches and inlets, and bold, rocky shores. Woodland and thick vegetation border the shore where it has not been developed for residential or industrial use, The total area of the bay is about 176 square miles. From Brenton Point to Newport to Providence, along the main axis of the bay, the distance is about 26 miles. The width of the bay averages four to five miles. Three large islands, Aquidneck, Conanicut and Prudence Islands, - and about a half dozen smaller islands lie within the bay. Conanicut and Prudence Islands divide the main portion of the bay into two long and narrow parts known as the East and West Fassages; Aquidneck Island separates the Sakonnet River from the East Passage, 9, TRIBUTARIES AND HARBORS The most important streams tributary to Narragansett Bay are the Blackstone River; the Taunton River, with Fall River Harbor at its mouth; and the Providence River. The Blackstone River, which has its source in Worcester, Massachusetts, has a drainage area of 540 square miles. Its tidal reach is known as the Seekonk River. Portions of the Seekonk River and Providence River con- stitute Providence Harbor, which with Fall River Harbor are the two most important commercial ports in the area. Newport Harbor and Lower Narragansett Bey are of major importance to Naval vessels. ii Si cea muy yyy eee erent Es ee 2 oe S Y ae Se wialaly on Sethe Flood waters of Hurricane "Carol" (August 1954) swept up the Providence River flooding industrial areas in Providence. Photo by C. Demerjien xe eK 1 i i i t < ‘ wie Ve i ‘? y i A L ee i / i i oh \ 1 4 ’ T , 1 We i i i ‘ y 1 Naw, : i ™ i v ' i f ny ‘i Fights « ’ iT © ¢ \ it + i 4 . i ly ii nn" 7) L ahi ® 7 nN if Mi } fa he yaa “iy Pi) aah a + a “i ea a ass Li I Ca n « ; 5 a } he Pheer alee Ne vent sands soaps LIE, ne ay ee pet ry a i hy or : he ee oes ere b i ‘Pe ae fT ane ee) tai, oa J i re wee ee nate j i ‘ é » i Le mii " OO, el iy ‘ al @. 10. TIDES AND CURRENTS Ocean tides enter the bay throush the East and West Passages end the Sakonnet River. Two approximately equal tides occur each day, a tidal cycle averaging 12. hours. ean tide ranges from 3.5 feet at Newport to 4.6 feet at Frovidence and spring tide from h.4 feet at “etrmort to 5.7 feet at Providence. Tidal move- ment is nearly simultaneous throughout the bay,, high and low tide for most points occurring within twenty minutes of high and low tide at Newport. Hirh water at Frovidence occurs about 10 minutes after hich water at Newport. The usual maximum flood or ebb current is from 0.5 to 1.0 knots; however, in narrow areas of the bay, the current is as much as 2.75 kmots as at the Sakonnet River bridges. For spring tides, the usual maximum velocities are about 20 percent greater than the above values. 11. GENDRAL GEOLOGY AND TOPOGRATHY a, Structure, The bedrock of the eastern and southeastern seaboard lowland of New England is predominantly gneissic and granitic, except where complicated by the presence of schist, as in the case of southwestern Khode Island, or where a low spot in the crystallines contains residual vounger sedimentary rocks. Many of the igneous rocks have been attributed to the Devonian Period, while rocks in the two most prominent depressions, the Boston Basin and the Narragansett Basin, ere largely carboniferous; thus the entire area is predominantly lower to middle Faleozoic in are. Glaciation and stream erosion were much more effective in tie sedimentery rocs of the basin than in the surrounding crystallines, and ceused the entire basin to exist as a depression. Narragansett Bay, however, occupies merely the southwestern portion of the basin, end represents the surface floodinse of some of the deeper valleys of the denression, Attempts have been made to visualize distinct structures in the basin. The rocks have been described as dipring steeply in a series of broken synclines and a rough estimate of two miles has been ventured for the thickness of Carboniferous strata represented in the basin, but the inter- pretation involved postulation of numerous faults, and appears somewhat contrived. b. The rocks of Narragansett Bay. The rocks of the bay are largely sandstones and shales, sometimes coaly, es in the deposits of the old "coal" mine north of Newport. Mineral alteretion is quite pronounced locally, presumably owing to adjacent granitic contacts north of the entrance to Mount Hope Bay, Newport Head, the southern tip of Jamestown Island, and the coast of Narragansett, the latter granite heving been established only rather recently as a younger intrusional body. Rock surface beneath the bottom sediments of the bay is highly irregular, attaining minus elevations of about hCO feet in places, with adjacent areas forming shallow rock pavements with almost no sediment cover, the rough structural configuration having been complicated by extensive pre-glacial erosion to form gorges now under a deep cover of glacial and post-glacial sediments. c. The sediments of Narragansett Bay. Borings indicate that the glaciers swept the bay, leaving a cover of their own, quite thick in places. The usual resulting sequence up-bay, resting on bedrock, is cobbles and boulder clay or reworked till, a ccnsider- able thickness of outwash silts and sands, capped by a few to fifteen feet of organic silts of recent origin; while deep gorges in the middle and lower bay areas trapped accumulations of silts and clays, sometimes in excess of 100 feet. d. Topography. Topography is governed by geological structure in that heavy outwash deposits from East Greenwich to Quonset pro- vide a low flat plains fluvio - glacial sands east of Point Nayatt present a slightly and undulating terrace; and projections of the old sedimentary rock structure stand out as moderately high islands. Maximum elevations of about 300 feet occur where the crystalling old land nears the bay, notably west of Greenwich Bay. Maximum elevations within the basin attain about 125 feet. 12, ARMA MAPS The area under study appears on standard quadrangle sheets of the U. S. Geological Survey at a scale of 1:31,680 and on a Geological Survey topographic map of the states of Massachusetts, Rhode Island and Connecticut at a scale of 1:500,000. The area is also shown on the Providence topographic sheet of the Army Map Service at a scale of 1:250,000. Narragansett Bay and the navigable parts of its tributary streams appear on U. S. Coast and Geodetic Survey charts Nos. 236, 278, 352, 353, and 1210, which are now being revised (1956). The Coast and Geodetic Survey is also preparing detail maps, at a contour interval of one foot, of areas in Providence subject to tidal flooding. ECONOMIC DEVELOPMENT 13. POPULATION Narragansett Bay lies in one of the most densely populated areas of the country. In density of population, Rhode Island ranks first and Massachusetts third in the United States. The population of the Narragansett Bay area is more than 725,000 (1950 census), including 586,000 in the Rhode Island portion and 139,000 in the Massachusetts portion. Aporoximately 85 percent of this population is urbane Populations by towns are given in Table 1 and the distribution of the population is shown in Figure l. TABLE 1 POPULATION OF CITIES AND TOWNS NARRAGANSETT BAY ARHA (1950 Census) City or Town Population Providence, Re lho eeeeevneeeeeeeve278 e082 8088088088 2h8 67h Fall River, MasSe @overeecercersceeeceseesceseee® 111,963 Pawtucket, I oslo @eeeeeesrececesreeseereere ee eT eeeene 81,136 Cranston, Rollo Coeeseecesevrecceessesececerteeene 55060 Warwick, Rollin coo0000b0d0000000000005000000000 43,028 Newport, ete @eceseeceoevseseseeceseeseese2eree eee ee 37,56L Bast Providence, Reale eececcsecccreccccsccccce 35,07) Moron Kanes town, “itelletledis «sles \clsicie a cls e ele clele slele 14,610 Bristol, Relo cocccccrcccseccescssescesecccese 12,320 South Ki.nztstown, Hele COeeeseecreegseeseeeoce sea 10,148 Seniciescien NEES cogcogccoocdoo ds bdognnadanoouD 6,566 Welreria ie Rtsuel lalate otatetatatale atelelejeta’alsieteyale ele) siei ets clelele 6,513 Barrington, Rele nccccccccccccsccccvesesececce 6, 2h6 Middletown, Rollo SeOCeeceveceesccercesevecvsevcecce 7,382 Portsmouth, ieee eiitteleteleleveleotel cls) ersiele s/s) cilc! ele! slclelisiclel ele 6,578 Swansea, MaSSe escccesccccccccsrescececsvecees 6,129 Seekonk, MaSSe eocccccvccsscescccccvcccccccc ce 6,10) Tiverton, Rele enccceccccsccccccccevcccevccece 5,659 Bast Greenwich, Rele cscscccccccccccccccsccccs 4,923 Dighton, MaSSe eecccercccccccesccccccccccsocce 2,950 Narragansett, REGIE G eoceceeeeeoceeeoeeseeegereeeeos 2,268 Freetown, MasS. scccccvcccccccerscaccscscecces 2,10L TABLE 1 (continued) POPULATION CF CITIES AWD TOWNS, NARRAGANSETT BAY ARBA City or Town Population Jamestown, Rele @eeeeesceeweeeeeaeeeseteoeoneeee 2,068 Little Comptor., RallgG oco0ad dd oGOGOKGAD00000C 1,556 Berkley, Masse @eeneeteeeeeoeeeeteeoeseoeeeene0@ 1,28) lh. INDUSTRY Most of the major industrial arees of Rhode Island and the ine dustrial city of Fall River, Massachusetts, are lccated ir the Narragansett Bay area. The employed labor force numbers approxi-= mately 196,200, of whom 63 percent are engaged in manufacturing, in contrast with the United States average of 25 percent. The economy of the area is centered around three major industries, textiles, metal trades and jewelry, constituting 80 percent of the manufac~ turing employment and 51 percent of the total employment of the areae Providence and Fall River are the chief manufacturing cities. Providence alone accounts for 7 percent of the metal trades and 91 percent of the jewelry-silverware industry. Fall River accounts for 50 percent of the textile and epparel industry of the area. 15. FISHERTES Fishing is one cf Rhode Island's oldest industries, dating back to early colonial times. Today, the value of the annual commercial catch of firfish end shellfish is about 5,000,000; this amount may vary somewhat from year to year. Ir 1955, more than $l,,600,000 worth of finfish and shellfish were landed at Kkhode Island ports, an increase of 11 percent over 195!:. The commercial finfish include both foodfish and "trash" fish, the latter used to produce animal feeds, glue fertilizer and other products. Flounder, herring, butterfish and scup are the principal varieties of commercial food- fish. The hard clam (quahog) fishery is of considerable importance, its value amounting to about $2,000,000 annually. Other shellfish species of somewhat less commercial importance are bay scallops, soft clams, oysters and lohsters. The estimated annual expenditure for marire sport fishing is more than $3,000,00C. The principal sport fish species are striped bass, bluefish and tautoge 10 IS 7 “ f > TA WwW 7 4 / x / a i fr ee Tie Pr. - As 2 (o} f FE | xr = | (c) =— a | P= I a4 i Fea = a —_—_—_ PAWTUCKET a So CRANSTON @ -—s N ( \ \ \ \ ot KS) tp cea RT ei e ‘s f SCALE IN MILES HURRICANE SURVEY NARRAGANSETT BAY LEGEND RHODE ISLAND-MASS. POPULATION DISTRIBUTION 1000 Population CORPS OF ENGINEERS U.S.ARMY NEW ENGLAND DIVISION DEC 1956 BOSTON, MASS. FIGURE | sia Pe seca i a t ‘ HORA ARO al , Oo iaue “*.. Pitese: Ne ah and he a fies a write tote obec In eh: Se A Pins vce itera pcan saree a maoul wo Sud, A GARDE. The ‘epoanmyl’ 4 neetdom, acter. | i mafulegn Bayi igs ea ror dics pet 7 mn ag. | are eer’ ie) Gia’: - i. af Yaa CG sitehalod oat onl easenisewe RL La tip cents Ne Bayi Nii NON) ea tap dell ak mig nel 2 ws ait i penn yy es wid , / ‘ohare. Viele ean rer ‘sacri dade. Capable ter # per Tinh Werines Aie Mae noe ayy TY aevARATSAK “ Copan i 16. AGRICULTURE Agriculture holds a relatively unimportant position in the economy of the area. Although the land of the state of rhode Island is fertile, only 1.5 percent of the labor force of the state is en- gaged in farming as a primary employment, and this percentage is decreasing as urban development expands into farming areas. In the less industrialized areas, however, particularly along the Middle and Lower Bays, there are a number of thriving farms. 17.2 NAVIGATION Narragansett Bay, one of the deep water harbors on the Atlantic coast, is the seaway to the ports of Providence and Fall River, which rank third and fifth, respectively, in commercial tonnage in New England. The total amual tonnage passing through the bay is about ‘ 10,000,000 tons, of which about 75 percent is destined for the port of Providence. Three distinct types of vessels comprise the traffic in the bay, — deep-draft commercial vessels, Naval vessels, and small fishing and recreational craft. The deen-draft commercial vessels carry cargo consisting prin= cipally of imports of petroleum and petroleum products, and of coale In 1955, these commodities accounted, respectively, for €5 percent and 10 percent by weight of the total cargoes received at Providence. In 1955, annual commercial vessel traffic passing through the bay totaled 2bout 370 vessel trips a year for vessels havirg drefts of 30 feet or greater and about 230 vessel trips for vessels having drafts between 25 and 30 feet. Commercial vessels having drafts of less than 25 feet made approximately 25,000 vessel trips to and from the various ports within the bay. Naval vessels using the bay include all types of modern fight- ing ships, which are part of the Atlantic Fleet (see paragraph 20). Thousands of small fishing and recreational craft navigate the waters of the bay in connection with commercial and sport fishing and sail- ing and motor boating. In recent years, tne number of pleasure craft, both sailboats and motorboats, has increased spectacularly. 1@. TRANSPORTATION The area, containirg the second largest metropolitan region in New England, is served by an extensive system of highways, railroads and airlines. Major highways radiate from Providence connecting the area with Boston, Worcester, Hartford, New London and New Bedford. da: U. S. Route 1 from Boston passes through Providence and then follows the westerly shore of Narragansett 3ay for nearly its entire length. The chief east-west highway is JU. S. noute 6, connecting Providence with Hartford, Fall River ard the Cape Cod area. State Route No. 11h serves Newport and other communities along the easterly shore. The main line of the New York, New Haven and Hartford Railroad from Boston to New York provides daily passenger and freisht service for the Providence area. Branch lines serve Fall Kiver and Newport. The Theodore Francis Green Airport in Yarwick, about 7.5 miles south of the center of Providence, is the center of commercial aviation. Major airlines provide regularly scheduled flights to all parts of the United States. 19. RECREATION Narragansett Bay has long been famous as @ recreétion and vaca- tion center. Newport is one of the oldest resorts in the United States. Other famous resorts are Jamestown and Narragansett. With more than 250 miles of coastlire, Narragansett Bay naturally features salt-water sports. Bathing is enjoyed from early summer until late September at public and orivate beaches. Striped bass, bluefish and tauLloe are ponular attractions for sports fishermen. A large number of yacht clubs and boat yards maintein facilities for small boats and fishine craft. Ir the summer there are frequent yacht races, includins suth national events as the lewport to Bermuda and Newport to Annasolis races. 20. DEFEISS ESTABLISHMENTS ‘Within the Lower and Middle Bays is one of the primary Naval bases of tne United States. The waters provide a natural land—locked, deep-water, ice-free harbor for the largest ships of the Navy. A complex of docks, repair yards, berthing areas, airfields and train- ing schools occupies large stretches of the coast, particularly in Newoort, Yorth Kingstown and Portsmouth. Among the more immortant establishments are the Newport Nav2l Base; the Naval War College and the aval Underweter Ordnance Station, both in “Newport; the Naval Air Station at Quonset Point in North “ingstown; the Naval Construc- tion Rattalion Genter at Davisville in North Kingstown; and the Naval Net vepot in Portsmouth. 12 CLIMATCLOGY 21. CLIMATE The temperate and changeable climate of the bay area is marked by four distinct seasons which are characteristic of the latitude and of New Encland. Owing to the moderating influence of the bay and nearby ocean waters and particularly to the veri- able movements of high- end low-pressure areas associated with continually chanzing weather patterns, extremes of either hot or cold weather are rarely long lasting. In the winter, coastal storms frequently bring rainfall, in contrast with snow in interior areas. In the summer, cooling relief from hot, humid weather is provided bry sea breezes from the east and southeast, thunder storms from the west, and cool air from the north. The prevail- ing winds are northwesterly in winter and southwesterly in summer, High winds, heavy rainfell and ebnormally high tides occur fre- quently in the hurricane months of Auzust, September ana October. 22. TENPERATURE The mean annual temperature of the area is approximately 50°F. February, the coldest month, has a mean temperature of 29°F, and July, the warmest month, has a mean temperature of 73°F, Freezinz temperatures, which are common from late November through Merch, occur on an everage of 105 to 110 days a year. The lowest temperature recorded in Frovidence was -17°F on February 9, 1934, and the hirhest temperature was 102°F on August 26, 1918. 23, PRECIPITATION The averaze annual vrecipitation is about 5 inches and is rather evenly distributed throuchout the year. teasurable pre- cipitation occurs on an averare in sbout one day out of three. The average annual rainfall at Providence, since the esteblish- ment of the Frovidence office of the U. &. “leather Bureau in 190 is slichtly greater than 39 inches. The heaviest pre- cipitation recorded at Frovidence for a 2ij-hour period was 6.17 inches on September 16, 1932. ‘inter snowfail in Frovidence averages 34 inches. A minimum of 11.8 inches was recorded during the winter of 1936-1937 and a maximum of 75.6 inches during the winter of 1947-1918. Further information on climatology will be found in Appendix C. 13 HURRICANE TIDAL FLOODS OF RECORD 2h, HISTORICAL HURRICANES Narragansett Bay, with its axis north and south and its mouth open to the Atlantic Ocean, lies in the path of the sreat hurri- canes which aprrosch the New Eneland coast. Since 1620, there have been recorded 25 damaging hurricanes and 38 hurricanes that narrowly missed the area without infiicting imrortant flood damege. Records indicate that during the period from 1635 to 1900 hurricane flooding of demsging proportions occurred nine times, in Aucust 1635, Aucust 1638, October 1723, October 1761, September 1815, October 1866, September 1869, October 1878 and December 1878. Detailed data on hurricanes producing tidal flooding aiong the southern New England coast are siven in Appendix A. The earliest hurricanes recorded in New England, including the Narragansett Bay area, appear in Governor William Bradford's "History of Plymouth Plantations, 1620 - 1647," and in Governor John Winthrop's "History of New England," which describe violent storms in 1635 and 1638 that created flood levels apparently higher than the recent floods of 1938 and 1954. Referring to the hurri- cane of Auzust 1635, Governor Winthrop wrote: "The tide rose at Narragansett fourteen feet higher than ordinary and drowned 8 Indians flying from their wigwams."" Of the storm of August 1638, Governor Winthrop wrote: "It flowed twice in 6 hours end about Narragansett Bay it raised the tide 1) or 15 feet above the ordi- nary sivring tide, upright." During the Great Gale of September 23, 1815, the flood waters rose to a height of 1.2 feet above mean sea level or 11.8 feet above mean high water at Providence. 25. RECENT HURRICANES Very early accounts of hurricenes in the area are brief, but since 1815, and particularly in the last 50 years, accounts have become increasintly more complete because of the growing number ot trained observers and rapid advences in the knowledge of meteorolocical phenomena. The contemporary reriod from 1901 to the present is mrked by fairly complete end scientific accounts of hurricanes. ‘1338 pee % SEPT. 16-31 AUG NZI9, 1958 OCTOBER : as x Dy, all cs RN AUGUST "5 HURRICANE SURVEY NARRAGANSETT BAY RHODE ISLAND PATHS OF UEC STORMS HURRICANE INTENSITY CORPS OF ENGINEERS, US ARMY NEW ENGLAND DIVISION BOSTON, MASS DEC 1956 FIGURE 2 ; emi cpedbseer iin ame sis setwrelesissbadebneciamasemensenes yell rial died eeu ( ’ r we 3 ‘ 1 ve I i ee ee * | an: Pia ¢ d Bae { ex aera oe Move ‘ Fa ee 1 ‘ 7 ae { " : a { 7 . ] i V4 ' t ee oe m7 ae S| Wel he) bes Oe Phy sales bic Ta OT ag 7 . vane | when ee i aT; {oye Mi He | . hed Ser Ah kool i ae v4 ' aan he ) < | ‘ < ey | wrt et mix $ ) ¢ ie Si iy $4) rd < 4 ; te, oy P ti yor ~ t 4 i i A Nuies ah Bien yh f 2 “ rot ni, & cs] + any ae me a E fe : nN =* 4) 4 7] S = b Tata Ry i + Se Raed “4 He! . neg ies simi: 74 val “heh Mie eee OY A ve ) Die et oa he Med in New Revi pani Ca en When at TO Vg? w ted Ww Ate oy Qovrenie ERA “HJ ind mya rg wt a coal nth e Mero bal t a ‘wet A 9 Sov Ws Babee} rt ta ena linge Mia Ree ane," whch dae Sth qtiveep Ses MASS SA gn ie bP eipetad: Ci oot lean Me & pasyns y back Ne setts booed i y ) metth ‘ “Ler ten J vr soe oo ge Se Aiest koe ie ae niet Bis oa ‘ pert og nate PE hi pend ee Ame Mis «eeu avn 9 6 wiih Te ee ‘Lis ee. jaf, Ls ate Pr, wth sty * . ; % ¥ \ sre Oras Ny zt ae ares al whee | whe nS aa bree ine ) ae Toad suai ‘uu? Meemoka’ cert = ae : sae a KMMee soaiNONT 40. RAT AR, Me MSE iets \, Thee aL yi i The three most damaging hurricanes since 1900 occurred in the 17 year period between 1938 and 1954. Two of these, the hurricanes ‘of September 1938 and August 195) (Carol), vroduced flood ievels of 15 to 16 feet above mean sea level at Frovidence, Both hurri- canes were nearly coincident with grevitational high tide, which contributed significantly to the severity of the flooding, The hurricane of September 19h); although a severe storm, struck at a time of low tide and flooding was consequently less severe. 26. HURRICANE FREQUENCY The distribution of recorded hurricane occurrences in the Narragensett Bay area by estimated degree of intensity is shown in Table 2, The fact that there is a record of 39 hurricane occurrences in the first 55 years of the 20th century (1901-1955), as compared with 2h occurrences in the 266-year period between 1635 and 1990 is attributed to the lack of records on early storms and is not believed to be indicative of any trend tovard greater frequency of occurrence in recent times. TABLE 2 HURRICANE OCCURR™NCES , NARRAGAWSSNTT BAY AREA Century 17th 18th 19th 20th 1635-1700 1701-1800 1801-1900 1901-1955 Total Intensity Major Tidal 2 2 5 3 12 Flooding i.oderate Tidai No Record a 5 if 13 Flooding Threatened No Record 3 6 22) 38 Area, Fath neer 2.1, Coast Totals 2 6 16 39° 63 As indicated by recorded facts, the Narragansett Bay area has experienced severe hurricane tidel floodine upon eivht occasions from 1815 to 1955, or an averare of one occurrence in 20 years. However, reliable informstion on hurricane hirh-water marks is availeble only for the three recent hurricenes of 193, 19h and 1954. There are no detailed data on the tidal-flood levels attained 5 in the five great hurricenes of the 19th century. Descriptive material of a generai nature incicates that the levels of flooding in these five storms probably did not exceed the levels experi- enced in 1938 and 1954. Using the three recorded high-water marks attained in recent hurricanes and the estimated flood levels in five hurricane occurrences during the 19th century, an eleva- tion-frequency curve hes been prepared. In preparing the curve, account hes been taken of the historical hurricanes of 1635 and 1638, their frequency being esteblished on the basis of the period from 1635 to 1955 and their elevations of flooding being assumed as higher than the 1938 flood level. With respect to seasonal variation of hurricane occurrences in southern New England, the period of greatest activity extends from early Aucust to the end of October. However, records indicate occurrences as early as the middle of June and as late as the middle of December, 16 HURRICANE CHARACTERISTICS 27. GENERAL DESCRIPTION The term "hurricane" is applied to an intense cyclonic storm originating in tropical or subtropical latitudes (between 5° and 20°) in the Atlantic Ocean north of the Equator. Accumulation of heat close to the surface of the water vrovides energy for water vaporization and the movement of masses of moist tropical air. A hurricane is characterized by low barometric pressures, high winds (75 miles per hour or greater), heavy clouds, torrential rain, tremendous waves and tidal surges. 28, ORIGINS AND TRACKS Most hurricanes that have affected the eastern coast of the _United States have formed either near the Cape Verde Islands or in the western Caribbean Sea. Hurricanes originating near the Cape Verde Islands move westward for a number of days with a forward speed of about 10 miles an hour, then usually turn north, frequently crossing the West Indies and sometimes striking the eastern coast of the United States. Hurricanes originating in the Caribbean generally move northward, striking Cuba, the Gulf ‘Goast or the eastern coast of the United States. After re curvature, the forward speed usually increases to 25 to 30 miles an hour, occasionally to 60 miles an hour, Cape Verde hurricanes commonly recurve (turn northward then east of north) any time after reaching the mid-Atlantic. Hurricanes that affect New England most severely usually arrive from the south-southwest after recurvature east of Florida and after skirting the Middle Atlantic coast. 29. WINDS AND BAROMETRIC PRESSURE The highest winds of a hurricane are those within a circular region extending from the edge of the "eye", or calm center, out- ward for 10 to 15 miles. The diameter of the eye is usually about 15 miles, although the eye of a mature hurricane is frequently 20 to 30 miles in diameter, Wind movement is not directly toward the low pressure cyclone center or eye of the hurricane but approaches the center in a counter-clockwise spiral. Consequently, the high- est wind velocities occur at points to the right of the center of the hurricane where the spiral wind movement and the movement due to forward motion of the center are in tle same direction. Since destruction by the wind is greatest in the area on the right side of the hurricane, tis area is kmown as the "dangerous semicircle". ay Atmospheric pressure falls rapidly as the center of the hurri- cane aovroaches and as the velocity of the wind increases. !inimum barometric readings do not always occur in the center of the eye. In some instances, the minimum is reached at the beginning of the calm period while in others the minimum is reached at the end of the calm period. Usually the barometric low is about two inches below the normal sea level pressure of 30 inches, Jlowever, in several hurricanes pressures of 2s much as three inches below normal have been recorded. In the United States, the lowest baro- metric pressure ever recorded was 26.35 inches at the northern end of Long Key, Florida, on Sevtember 2, 1935. 30. RAINFALL Another characteristic of a hurricane is the heavy rainfall that usually accompanies the storm, At the edge of the disturbance rainfall is light, normally in the form of showers. As the center approaches, the showers increase in frequency end intensity, be=- coming heavy to excessive near the eyee The heaviest rain usually falls ahead of the eye, driving torrentially from spiral bands of clouds that sometimes produce nearly two inches of rain per hour, For ea 24-hour period, amounts exceeding 20 inches are not uncommon. Record rainfall near the Narragansett Bay area occurred during Hurricane Diane (August 1955) when 18.15 inches of rain fell at Westfield, Massachusetts, on the 18th, 32. WAVES Much of the hurricane camage is caused by waves generated by hurricane winds. Vessels at sea suffer greatly in the northeast quadrant of the hurricane and in the confused seas of the storm center where waves 15 feet or more in height have deen revorted. These mountainous waves appear in wild nyranidal masses and the magnitude of their destructive mower is revealed only in the appalling record of lives Jost and shins sunk at sea or wreclced on Ssnoals and shores. Such gient ocean waves will traverse tremendous distances while diminishing in size and etreneth, reaching distant shores one or two cays in »cvance of the hurri- cane and causing damage even before the onset and retease of the fury contained in the storm proper. In the deep water of the open ocean, the height, period and velocity of many of the waves produced 2re a function of the wind velocity. ‘The ultimate size of the waves cenends unon the force and duration of the wince and the fetch or cistance the wave travels. As ocean waves cone into slical waters, their forward movement is slowed by friction on the bottom, and tnuey rise to 2 new height 18 74° ne 70° ie 66° N C A N A D A / \ Da) es) Sea Tans | 31 AUG 1954 a / “N yi, rc - 4 , NEW ,) BRUNSWICK Bil SE IES} 14-15 SEP 1944 Eastport n 44° [Sal "DIAN e" 17-20 AUG 1955 5 PROVIDENCE @ > NARRAGANSETT BAY 68° | HURRICANE SURVEY NARRAGANSETT BAY, R.I. TRACKS OF SELECTED HURRICANES CORPS OF FRGINFERS US ARMY NEW SL AND DIVISION 40" Ew ENGLAND Divisio ——- BOSTON, Mans Orc +958 SS | STALE IN MILFS FIGURE 3 — nm ' ‘ , Taree f NA Th Doge ae Pei i 6 hy fia nah e bier bo ter soe j 4 i My This et dl i ‘ny A lees i he “L. i hag ; a ere em icecbemen Tris jab) tae . ‘oat, ‘ A par . : an ! ee Pus mio i tg) i Ly eed pee Ni Pri Fi Th” | ica Soe bY A Rangel ‘ow nT. ; 1 SRR ie FER, eg a Pupttiotd yg Naren peck: e . Co ae Bary sores before they are dissipated in shoal waters or break on the shore, Driven by hurricane winds, the breaking waves will run up on a shelving beach or overtop vertical structures well above the wave heights, so that reports of wave and flood damage from 5 to 25 feet above water level are not uncommon. Hurricane waves do great damage to shorefront land and buildings and to vessels and small craft. In the hurricane of 1938, the waves within Narragansett Bay carried a number of lighthouses off foundations which were well above normal water levels, 32. TIDAL SURGES Although hurricane winds have caused the deaths of thousands, and thousands more have lost their life in ships destroyed at sea, most of the losses of human life and property in hurricanes are due to flooding. Flooding, one of the most devastating effects of a hurricane, results from movement of the storm surge, or substantial rise in water levels, onto a shoaling coast and into a bay or inlet. The. surge is caused by a combination of hurricane winds and low barometric pressure in a storm having a track and speed of forward movement synchronized with the normal pattern of tidal movement and oscillations of the sea in the oven ocean, Usually the rise of the sea is gradual as the center of the storm approaches but sometimes it comes with great swiftness. Rising waters accompanying hurricanes have been called "tidal waves", although they are not tides in the ordinary sense. The history of terrible storms reveals many instances of cities and towns flooded, with thousands of lives lost, evidence that such rises are not always gradual. Usually the level of the storm surge is increased by a rising ocean bed and favorat:le shore contours, factors which similarly affect the astronomical. tide in shore locations. The ordinary rise of the tide amounts to only one or two feet in the onen oceans, while its ranze is often ten to twelve feet at coastal points. In certain bays and channels the rise is 25 to SO feet above low water. The times of ebb anc flow of such tices are, of course, well known, but the storm curge cones so rarely to any one commu- nitv that it is seldom anticipated in its fvlly ceveloned form, A well-defined storm surge is not developed unless the slope of the ocean ted and ccntovr of tie coastline are favorable to its rise, in combination with the »roner cirection of the storm track ana speed of movement. 19 im the cper ocean the rise due to the stor: surge seldon exceeds 3 feet, but it increases considerably on the continental shelf and alongs the coastline where it builds uo in height, in muca tiie Sane way thet a grounc swell ':vilds up in shoal water, An uccditional rise in level occurs due to the effect of hurri- cane wines ‘lowing over shoaling coastal waters and shallow bays and inlets, depending on the fetch, the cepth of the water, and the wind intensity anc duration, The rises in level from the cominetion of of °shore surge and local tind effects may range from & to € feet above normal. hich tide on the coast, and to 12 or 1 feet above norma] high tide in bays and inlets. DE5iGN HURRICANE TIDAL FLOOD 33. ANALYSIS OF THP HURRICANE SURGE 4s a hurricane progresses over the open water of the ocean, a tical surge is »uilt up, not.only by tine force of the wind and the forward movement of the storm wind field, but also by differ- ences in atmospheric pressure accompanying the storm. This surge is further increased as the storm approaches land over a gradually shoaling ocean ted and is influenced ccnsiderably by the contours of the ccastline., An additional rise results when the tidal surge invades a bay or estuary and hurricane winds drive waters to higher levels in the shallow waters. Tidal surges are greatcr and the tidal flooding more severe in coastal communities which lie to the right of the storm path, cue to the counter-clockwise spiraling of the hurricane winds and the forward movement of the storm. ‘he actual]. height reached by a hurricane tidal surge and the consequent damazes incurred depend on many complicated factors. 3h. WIND FIELD AND PantGIETRIC PRESSURE The maximum gust of wind recorded in any hurricane in Mew England is 186 miles per hour; a sustained 5-minute velocity of 121 miles per hour was recorded in the September 1938 hurricane at the Blue !ill Observatory, Milton, Massachusetts, about 30 miles north of Providence. At Providence, the maximum recordec l-ninute sustained wind velocity was $5 miles per hour, with a S-ninute sustained blow of 67 miles per hour and maximum estimated gust of 125 miles per hour, in 1938. During the hurricane of September 19), the maximum gust in New ingland was 10h miles per hour at Chatham, Massachusetts, about 5 miles east of New Bedford. Peak gusts measured during Hurricane Carol (August 20 uOTS STUIUIOT yuaeurdo[aaaq roqaepP Joystag Aq pazyturqns oj04d "19ajeM YSTY UBAUT BAOQE 422} [7 61 39913G ‘“($G6I IsNsNy) ,,[OIeD,, FUeITIAIN} dutinp pues] epoyy ‘TO stig 3e uoT}Ie BALM Sor Ke er emndes Ls bigs Avent Ota! A nm ad i ‘ if te 7 n a ee eee (gece ae ne, el TEP Ae es Wy wat) wht og ae cg zs i) at "A ; ) ; ‘ ie bie - ( ” d a ‘ . w - re 7) ed ‘ bake iotiesy 4 i‘ { i jl j i Mi Ro a) i, \ Ad is 1954) were 12 miles per hour at Mount Wasnington in New Hampshire (170 miles north of Providence), 130 miles per hour at Block Island, Rhode Island (45 miles southwest of Providence), 125 miles per hour at the Blue Hill Observatory and 105 miles per hour at the Theodore Francis Green Airport in Warwick, Rhode Island, (7.5 miles south of the center of Providence). The diameter of the low-pressure area in the center of hurri- cane storms has measured as mich as 30 miles but usually ranges from 10 to 15 miles. The lowest barometric pressure ever recorded in the Western Hemisphere was 26.35 inches in the Florida Keys during the hurricane of 1935. The minimum in New England was 28.0), inches re- corded at Hartford, Connecticut, during the 1938 hurricane. The minimum at Providence was 28.51 inches in the September 19) hurri- cane; the lowest pressure recorded in New England during this storm was 28.30 inches at Westerly, Rhode Island. In Hurricane Carol (August 195),), 28.20 inches was recorded at Storrs, Connecticut, and 28.79 inches at Providence. Further data on wind velocities and barometric pressures in past hurricanes are included in Appendix ‘Be 35. ASTRONOMICAL TIDE AND TIDAL FLOODING An important factor influencing the height of the hurricane surge is the stage of the normal tide at the time the surge arrives at the coast. The September 1938 hurricane tide reached Narragansett Bay approximately concurrent with the predicted high tide, whereas the August 195), hurricane tide occurred about two hours after the predicted high tide. The September 1938 surge elevation at Providence was 15.7 feet above mean sea level and the August 195]; elevation was 1.7 feet above mean sea level, but the difference between predicted tide height and surge height was 13.3 feet in 195) and 12.6 feet in 1938. Thus the 195) flood would have been about two feet higher and about 0.7 foot above the 1938 flood level had it occurred at the time of high tide. The September 19) hurricane tide arrived at Providence about one hour before the predicted low tide and therefore did not produce major flooding. It reached an elevation of only 9.9 feet above mean sea level at Providence although the rise above predicted tide elevation was 11.6 feet. In determining future tidal flood levels, one factor to be con- sidered is the rise in mean sea level that is taking place along the New England coast. Continuing investigations being made by the U. S. Coast and Geodetic Survey in regard to changes in sea level indicate that mean sea level has risen at a rate of approximately 0.02 foot 23, per year since 1930 (see report by the Council on Wave Research in Proceedings of the First and Second Conferences on Coastal Engi- neering, 1952). If this trend continues and storms of the magnitude of the 1938 and 195), hurricanes were to occur at the end of the next 50 years, flood levels would be approximately one foot higher than were actually experienced in these storms. The effect of rising sea level is to increase the severity of future hurricane tidal flooding. 36. STORM TRACKS Each of the three great recent hurricanes namely those of 1938, 19) and 195 followed a path from 20 to 80 miles west of Narragansett Bay, thereby placing the bay in the sector of the strongest and most damaging hurricane winds and in the sector where the storm surge is highest. Figures 2 and 3 show these storm tracks, 37. SELECTION OF DESIGN HURRICANE TIDAL FLOOD In the design of protective works, structures must be built of sufficient height and strength to withstand the most severe combi- nation of storm tide and wave action that can reasonably be expected. A "design hurricane" for use in determining the required height of protective structures has been established through the joint co- operation of the U. S. Weather Bureau and the Beach Erosion Board, assisted by the Texas A & M Research Foundation. The basis of the design storm is a transposition of the 19), hurricane because this storm when it was off Cape Hatteras, had the greatest amount of energy of any recorded storm along the Atlantic Coast. However, he 19); hurricane when it struck New England was not nearly so serious as either the 1938 or 195) hurricanes because (1) its energy had been partly dissipated over the land north of Cape Hatteras, and (2) it struck at a time of low tide. In deriving the design hurri- cane, the 19) storm was transposed so that it would be over water between Cape Hatteras and the New England coast, resulting in less drop in barometric pressure at the center of the storm than actually occurred in 19));. The transposed hurricane, having the intensity of the 19); hurricane off Cape Hatteras, was assumed to move with a forward speed of 0 knots (about 6 miles per hour) in a northerly direction and to pass over New England with its center 9 nautical miles west of Providence. This would place Narragansett Bay in the most critical area of the storm. Wind velocities were ascertained by the U. S. Weather Bureau for the passage of the storm, and a velocity of 76 miles per hour, the sustained wind velocity over most of the Narragansett Bay area, was selected as the design=-storm velocity. The storm-tide potential at the entrance to Narragansett Bay was determined, including a preliminary estimate of the height of the surge after its propagation along the coast and up Block Island Sound to the entrance of Narragansett Bay, 22 38. DESIGN HURRICANE FLOOD LEVELS The computation of storm-tide potentials, including a description of the method used, is contained in a report dated March 1956, "Dynamic Storm-Tide Potentials," prepared by the Devartment of Oceanography of the Texas A & M Research Foundation in connection with research for the Beach Brosion Toard. In accordance with procedures outlined in this report, the 19), design hurricane storm-tide potential off Newport Harbor at the entrance to Narragansett Bay was calculated to be 12.8 feet above mean sea level or approximately two feet above the level of the 1938 hurricane. By a combination of analytical methods and model tests, the level was determined to be 18.7 feet above mean sea level at Providence or about three feet above the actual 1936 flood elevation. The full development of the design hurricane is given in Appendix B. 3°. DESIGN WAVES AND WAVE RUN-UP Wave heights with the design wind velocity of 76 miles per hour are estimated to be 25 feet from crest to trovgh at the entrance to the bay and from 6 feet to 9 feet within the bay depending on the fetch and depth of water (see Table 3). These are "significant" wave heights and would be exceeded by individual waves by as much as 60 percent. The amount of wave run-up (the height above still-water level reached ty the rush of water up a structure on the breaking of a wave) on the seaward side of protective works would exceed the wave heights shown in Table 3. LO. STREAM FLOW COINCIDENT WITH HURRICANE TIDAL FLOODING Heavy rainfall is normally associated with great hurricanes. Warm, moisture-laden air is carried in over the land from the ocean by northeasterly winds in advance of a hurricane causing heavy preci- pitation before and at the time the hurricane strikes. Consequently, high river runoff and severe flooding are likely to occur at the same time as a hurricane tidal flood. An -example of this situation was provided by the hurricane flood of September 1938 when many of the rivers in New England overflowed their banks and caused extreme flood losses one day in advance of the hurricane, while on other rivers, such as the Thames River above New London, Connecticut, fresh-water flooding occurred two hours before salt-water flooding. See Appendix C for a detailed discussion of stream flow. 23 “ABLE 3 DESIGN WAVE HBICHTS NARRAGANSETT EAY Significant Wave Height Period Fun=-U9 (ft) (sec.) es Lower Bay Barriers East Barrier South Side 25 11 31 (Stone Break- water) North Side 6 5 Ras n n ‘Iest Darrier South Side 20 aay 25 " n North Side 7 5 9 ‘ u Tiverton Barrier South Side 9 fi aBt tt " North Side h L9) e WR WN Fox Point Barrier South Side 6 5 6 (Vertical Con- crete Wall) 265 265 " 1? ine) North 3ide hl, DESIGN STHEGI FLOW Of the great storm rainfalls recorded in New gngland, only the September 193€, Seotember 19), and August 195) (Carol) rainfalls were associated with major hurricane storm tides. Since the Sep- tember 1936 storm had the greatest rainfall. of record associated with hurricane winds and the highest recorded tide levels, it was adopted for design studies. The storm rainfall, which was centered 2h, over Buck, Connecticut, was transposed to the area in Narragansett Bay above the investigated tidal barriers. For studies of the area above Fox Point in Providence, the 2li-hour storm rainfall of 9.5 inches was centered over the Woonasquatucket and Moshassuck River Basins, and for studies of other areas the 72-hour storm rainfall of 14.2 inches was centered over the Blackstone River Basin. 25 EXTENT AND CHdracTser OF TYE FLOOD ARwA 42. ‘Lhe hurricane of Juzust 1954 (Carol) caused destructive tidal flooding along most of the 250-mile shoreline of the Narra- zansett Jay area between Point Judith on the west and Sakonnet Point on the east. Flood levels ranged from 9.8 feet above mean ‘sea level at Newport to 14.7 feet above mean sea level at Provi- dence. Flood levels in tie nurricane of September 1938 were aigher by one foot. Some 20,500 acres in the States of rhode Island and tlassacnusetts were inundated in each of tre two floods. The 1938 Flood took more than 250 lives in Rhode Island alone. In the 1954 hurricane 19 lives were lost in zhode Island, the majority by crowning in the flooded areas of Narragansett Bay and tne south shore. By far the principal flood damave center is the city of Providence, woere about one-third of the area's population of more than 725,000 reside. In tne 1954 flood, about 500 acres of the commercial and industrial center of Providence was inundated and damages amounted to aproximately one-third of the total flood damages sustained (see paragraph 3). The remaining two-thirds of the damages aredistributed around tne eastern and western shorelines of the bay and in the Massachusetts communities bordering Mount Hope Bay. The larger Rhode Isiand suburban and residential communities on the shorelines are Cranston, Warwick, Warren and Bristol in the Upper Bay and Newport in the Low2r say. Fall River, Massachusetts is tne largest community on Mount dope Bay. The shorefront nas been extensively developed for recreational purposes. in tne Lower Bay, where najor U. 5. kaval installations are locuted, losses to Naval property nave been neavy. For a fuller aiscussion of the extent and cnaracter of the flood area, see sppemeub se Uo 26 ae ae aoarece cgi: Sot een) bass : C a i iit on ms OW mec terete: nt Se ane oe. en eee Flood waters of Hurricane "Carol" (August 1954) receding from center of business district in Providence. Waters rose as high as eight feet at peak of flood. Photo by Dennis A. Murphy Pit aera es Net beri if t ; ian |i Say . sot) gothooes (hee! tonguds Aiea ta font 4 ih sade agi A& 2BO% cue y ; ‘ " : er A a w) oe peat, ah stat “@ oid a4 a a yt "oh oh , ian iy at hae BAL) fa i HURRICANE TIDAL FLOOD DAMAGES 43. EXPERIENCED DAMAGES Hurricane Carol of August 195 left in its wake a total flood loss of about $92,000,000 in the Narragansett Bay area. Almost 80 percent of this loss was sustained by residential, commercial and public property, including U.S. Naval property. The remainder was sustained by industrial, rural, highway and railroad property, and public utilities. See Appendix D for a detailed discussion and tabulation of damages. The city of Providence suffered far greater damage than any other locality caught in the path of Hurricane Carole losses in the city amounted to more than $41,000,000. The heart of the businesssectim was inundated by to 8 feet of pol- luted salt water. Hundreds of commercial establishments suffered heavy losses, including in many instances a total loss of stock and equipment. Industrial losses in the city amounted to over $6,700,000. Along the western shoreline of the bay south of Providence, from Cranston to Point Judith, tidal flood damages amounted to al- most $28,000,000. Two areas particularly hard hit on the west side were ‘arwick and North Kingstown. Tidal flood losses on the east side of the bay were almost as high as those on the west; in the area extending from East Providence to Sakonnet Point, including the Mount Hope Bay area, damages totaled more than %23,000,000. Flood damages in the hurricane of 1938 were even greater than in Hurricane Carol. Although no accurate evaluation of experienced 1938 damages is available, it is estimated that a recurrence of the 1938 flood stages at price levels prevailing in 1956 would cause losses of about $120,000,000, of which nearly $8,000,000 would be incurred within the Massachusetts portion of the Narragansett Bay area, as shown in Plate 2. In addition to the evaluated losses in the Narragansett Bay area, there are categories of losses which were not included or in- cluded only in part, because loss information in usable form was meagre or unavailable. Available evidence indicated, however, that these losses were substantial in the tidal flooding of 1938 and 195). These categories consist of (1) tangible losses to non-fixed or transient items such as craft afloat and vehicles parked on streets or in parking lots; (2) tangible losses outside the immediate flood area; and (3) intangible losses such as loss of life, health, security, and detrimental effects upon national defense, which are either indeterminate or monetarily unmeasurable. 27 4. RECURRING DAMAGES Estimates have been made of the damages for flood stages equi- valent to those of the 1938, 19h, 1954 and design hurricanes and for other recent hurricanes and severe storms based on stage-damage relationships obtained from the damage surveyse These recurring losses are summarized in Table 8 at 1956 price levels. In the development of recurring losses allowances have been made for (1) the anticipated effectiveness of individual plant flood protection, (2) the recovery of loss potential at property completely destroyed, i a general change in price levels due to increased costs, and (4) the estimated economic growth of the area. lS. AVERAGE ANNUAL LOSSES Average annual tidal flood losses in the Narragansett Bay area have been estimated at $5,922,000 at 1956 price levels. These losses were derived by correlating stage-damage,stage-frequency and damage- frequency curves in accordance with standard practice. A stage-fre- quency curve, based upon the known peak elevations of recent hurri- canes and hish water and peak elevations estimated from historical data of flood-producing storms of the past 321 years, was correlated with stage-damage relationships, referenced to the 195) hurricane tidal-flood crest, to arrive at damage-fre uency curves, as described in Appendix D. In view of the lack of precedent for estimating annual losses due to tidal flooding, an alternative method of estimating annual losses was used for comparison, based upon the assumption of a ‘recur- rence within the next 50 years, under economic conditions existing in 1956, of the hurricanes of 1938, 1944, and 1954, and 22 flood- producing storms. A recurrence of the flood stages of these hurri- canes and storms within the next 50 years in the protected area would cause an estimated total loss of #227,200,000, or an average annual loss of #4,5l,000 in the 50-year period. The annual loss derived by this method is comparable to that derived by the fre- quency method. 6. SCARE COSTS In addition to damages from tidal flooding, losses are incurred in the flood area by the institution of temporary preventive meas— ures upon advice of hurricane warnings, whether flooding occurs or not. Scare costs of a single hurricane warning are estimated at 325,000. Based on a frequency of three hurricane warnings in a 10- year period, average annual scare costs amount to $98,000. Appen= dix D discusses in detail the derivation of recurring losses, an- nual losses and scare costs. 28 "0D [euanor aoueptraorg Aq oj0Y4d ‘peseurep A[snotaes si9yj0o Aueur pue poeforjsep ei1am sawi0y 09 vey stoUr usYyM (FG6T ISNSNy) ,,JoreD,, FuUBdTIINY BSutinp paerind90 uotjoNI4sep Te[TUIS “S61 Tequieqdeg so auRdTAIN]] “pue{s] espoyy “YAMIeM ‘JUTOg yNoOTUITUOD ye edeUTep pooTT nog 2 Apagproons RS cs pantiok pena. cad He sapecne ; i haps ne ey Wreckage left in Providence by subsiding flood waters of Hurricane "Carol" (August 1954), Photo by C. Demerjien [ee ms settee ee > Sandbagging of entrances to an electric generating station. In addition to actual flood damages, losses are sustained due to temporary preventive measures taken during a hurricane ''Scare'. Photo by E. F. Walsh EXISTING CORPS CF ENGINEERS' PROJECTS 47. There are no existing or authorized hurricane protection proj- ects in the Narragansett Bay area. Twelve vrojects for the improve=- ment of navigation have been authorized of which eight have been completed. In addition, there are six authorized navigation surveys and four authorized preliminary examinations for navigation. Although these projects would have no effect on hurricane-induced tidal flooding, the projects which include breakwaters would reduce wave action. The projects would also have some influence on the selection of sites for, and the design of, proposed protective structures. In addition to navigation projects in the area, there are four authorized flood control projects on the Blackstone River, two of which, the local protection at Woonsocket, Rhode Island, and the Worcester Diversion project, are under construction. The others include a local protection project at Pawtucket, Rhode Island; and a flood control reservoir at West Hill, Massachusetts. Only the reservoir project would affect the runoff from the Blackstone River, None of the others would reduce flood flows entering Narragansett Bay from tributary rivers during heavy rainfalls accompanying hurri- canes and so would not affect the design of hurricane protection structures. IMPROVEMENTS DESIRED 8. VIEWS OF LOCAL INTERESTS The three hurricanes of 195, - Hurricane Carol (August 31), Hurricane Edna (September 11) and Hurricane Hazel (October 15), following so closely on the disastrous flooding of 1938, served as powerful stimulants to local interests to seek positive means of protection against hurricane tidal flooding. The danger resulting from recurring hurricanes was clearly recognized as a grave threat to the economy and growth of the area, Jitizens' groups, municipal officials and representatives of the State of Rh.de Island earnestly pressed for quick actior on legislation for tidal flood controle Delegations from Rhode Island and other New sngland states, partici-~ pating in Congressional hearings held as an aftermath of Hurricane Carol, urged that hurricane damage surveys of stricken areas in New England be made with a view to recommending protection. ‘The Governor of Rhode Island, in testimony before a Senate Public Works subcom- mittee, declared that most of the damages in Providence resulting from Hurricane Carol could have been prevented by dams or seawalls 29 in Upper Narragansett Bay. He also asserted that vrotective works were 2 Federal responsibility. Local interests urged rederal participation, claiming that Since, in princivle, salt-water flooding is in no way different than fresh-water flooding, Y"ederal responsibilities in river flood con- trol should be extended to include tidal flood control. Further, local interests expressed the ovinion that protective barriers in Lower Narragansett Bay wovld justify Federal particivation since the interests of two stetes would be involved, ard an important area in the bay necessary to the national defense would be affected. The cost of such large-scale engineering structures, it was considered, would be more than the states and municipalities concemed could reasonably be exoected to spend. l9e PROPOSALS FOR PROTECTION A number of specific proposals have been «¢.dvanced by local interests for hurricane floed orotection. The majority of these proposals have been for consideration of barriers or dams at svecific locations in the bay tnat would afford meesuresle protection against tidal rises for the areas tehind the berriers. b+ least 15 plans involving 25 locations for barriers, as listed below, were preserted in sufficient detail to merit careful examination and review. a. Unser Providence River barrier plans (1) Ship Street, Providence (2) Sovth Street, Providence (3) Point Street, Providence (4) Fox Point at Tockwotten Street, Providence. Two alter- native plans provosede be. Lower Providence River plans (1) Harbor Junction ssharf, Providence (2) Sassafras Point, Providence (3) Fields Point, Providence, to dast Providence. Three alternative plans nropvosed (4) Pawtuxet Point, Edgewood, to Sabin Point, East Frovidence (5) Gaspee Point, Warwick, to Bullock Point, East Providence (6) tonimicut Point, warwick, to Nayatt Point, Barrington 30 c. Greenwich Bay olans (1) Cowesett to Cedar Tree Point in “arwick (2) Sally Rock Point to Buttonwoods in Warwick d. Lower Narragansett Bay barriers. A plan for barriers across the Yast and West Passases near the mouth of Narragansett Bay. e. Series or subsurfece barriers. A plan for subsurface barriers in the Middle and Lower Bays. f. Sakonnet River barriers (1) The Hummocks, Portsmouth, to Tiverton (2) Island Park, Portsmouth, to Tiverton (3) McCurry Point, Portsmouth, to Tiverton (4) Sandy Point, Portsmouth, to Tiverton (5) Black Point, Portsmouth, to Little Conpton g- Local protective measures. In addition to the above bar- rier plans, locel interests in the towa of Sristol nave requested consideration of a breakwater in the harbor to protect waterfront property and commercial and pleasure vessels azeinst hurricane waves. A number of towns have éelso proposed the protection or acquisition of vulnerable beach areas and zoning of ereas below an elevation of 20 feet above mean sea level, to be eccomplished jointly by the State of Hhode Island and Town gzovernments. 50. PUBLIC HEARINGS Public hearings were held in Providence and Newvort, Rhode Island, and Fall River, Massachusetts, on 1, 2 and 3 October 1956, respectively, to permit locel interests to cresent their views con- cerning the character and extent of the protection desired and the neec for such imorovenents. A total of 163 attendea the meeting ir Providence, 151 in Newport and 65 in Fall tiver. Federal, state and local officials; representatives 2f civic, commercial and industrial interests; and private individuals attended the hearings. A majority of the participants approved of hurricane flood-control structures in the Providence area and at the mouth of Narragansett Bay. A sum- mary of the views and ovinions expressed at the hearings appears in paragraph 65 and in Appendix G. 31 HURRICANE FLOOD PROBLEMS ANDC SOLUTIONS Sle URRICANE FLOOD DAMAGES Hurricane damages result chiefly from (1) salt-water flooding by the hurricane surge (2) action of storm-driven waves, (3) fresh- water flooding resulting from torrential rains, and (l) effect of high-velocity winds. This report is limited to the damages arising from salt-water tidal flooding and wave action. Fresh-water run= off and flood damages are considered only to the extent that they affect areas subject to tidal flooding. Along low coastal areas and in narrow river valleys, flooding is generally the chief con- cern. Hurricane Carol (195) caused severe flooding of shore- front areas in the Narragansett Bay area, and in the following year Hurricane Diane inflicted enormously heavy flood damages along river valleys in Connecticut, Massachusetts and Rhode Island. Hurricane damages result from loss of life and property, hazards to health, disruption. of normal economic activities, and costs of evacuation and reoccupation. Some types of damage cannot feasibly be prevented although they may be relieved by careful planning. Effective protection against hurricane winds, for instance, can be relieved to some extent by the adoption of higher builaing-code standards, as has been done in some localities. Damages resulting from tidal flooding of coastal areas or fresh- water flooding of river valleys, however, can be significantly reduced in many cases by adequate protective structurese 52. POSSIBLE PROTECTIVE MEASURES CONSIDERED FOR NARRAGANSETT BAY Protective measures fall into the following categories, dis= cussed below: (a) hurricane warning and emergency flood mobilization measures; (b) revision of zoning regulations and building codes; (c) local protection, i.e., protective structures such as dikes, walls, breakwaters, bulkheads and local tidal barriers designed to protect ind@tvidual portions of the shorefront subject to tidal flooding; and (d) large-scale tidal flood barriers designed to prevent a hurricane surge from entering a major portion of the bay. ae Hurricane warning and emergency flood mobilization measures. A hurricane warning system, combined with emergency mobilization, would materially aid in preventing loss of lite and property. However, such a system would not alleviate the problem of physical inundation of land areas. Considerable time is required for emergency pre- cautions for homes, buildings, goods and other property such as boarding-up 32 and sand=-bagging lower floors and windows, evacuating low-lying areas, removing goods and equipment to higher levels, pulling small craft ashore, driving vehicles to high ground, and flying aircraft out of the area. A warning system, no matter how — extensive and elaborate, may not provide sufficient time for adequate precautions. The hurricane of 1938, for example, which was at one time reported stalled off Cape Hatteras, North Carolina, swept over the Narragansett Bay area, almost wnannounced, only 8 hours later. Hurricane alerts and near misses that result in "scares" only seriously interfere with the normal activities of the affected residents and mean undue hardship and great economic loss. The entire central business area of Providence, for instance, was evacuated, after long hours of sandbagging and construction of barricades, in anticipation of Hurricane Hazel (September 195h) which eventually moved up Chesapeake Bay and across Lake Erie into Canada, avoiding the Narragansett Bay area entirely. For the Narragansett Bay area, a "scare" has been estimated to cost about $325,000. Adequate hurricane warnings are necessary, however, to supplement any plan of protection for Narragansett Bay, partic- ularly for barriers with gated openings where closures of the gates against tidal‘ flood rises would be contingent upon evaluation of storm conditions. As part of its responsibility for improved weather services in connection with major storms and hurricanes, the Weather Bureau has established a "severe weather" network along the Atlantic coast, utilizing powerful radarscopes. The Weather Bureau office in Rhode Island, at the Theodore Francis Green Airport in Warwick, is linked to this network by means of a radar installation on Nantucket, which has a range of about 250 miles. This installation is backed by others at Boston, Worcester, Hartford and New York City. b. Revision of zoning regulations and building codes. Con- sideration of the warnings and emergency measures above leads to thought of more permanent relocation of goods and equipment to higher floor levels, relocation out of the flood area entirely, or of more substantial construction to resist the destructive forces of high water and waves. State and local governments have proposed adoption of zoning restrictions to prevent new construction in critical flood areas and revision of building codes to require sturdy structures for areas where buildings were demolished by the storm tide. For existing concentrations of homes, commercial establishments and industries, such measures have met with strong opposition because of the high investment in property and the prospective loss to property owners and municipalities. The responsibility for enacting legislation on zoning and building regulations lies with the states and mmicipalities con- cerned. After Hurricane Carol (1954) the State of Rhode Island embarked on a shore development program to aid communities by acquiring, for recreational and wildlife development, private 33 shorefront property endangered by recurring hurricane floods. Sub-= sequently, the program was modified to stress beach erosion control rather than shore development. A number of communities have applied for state aid under this program. ce Local protection. Four general classes of local works have been considered. (1) Individual measures. Since Hurricane Carol, a number of the larger industries and business establishments in the flood area have installed permanent or semi-permanent measures to protect their physical plants against hurricane flooding. These measures includes (a) Construction of flood=-proof structures. (b) Construction of flood walls around individual properties. (c) Permanent closure of windows and other openings exposed to flood waters. (d) Installation of valves or gates to prevent backup in pipe lines. (e) Installation of pumps to control seepage : and interior drainage. (f) Changes in the utilization of space subject to flooding. Most of these protective measures constructed by private interests are as yet untested and of uncertain effectiveness. They are also costly, not only in materials and labor, but also by reducing productivity. It is inconceivable how such measures can be generally adopted over the bay area without proving vastly uneconomical as com- pared to alternative flood protection methods. (2) Protection against flooding by local barriers, dikes and walls. To be effective against hurricane tidal flooding, such structures would require heights of approximately 20 feet or more above mean sea level to protect against wave attack and wave over=- topping. At many locations high walls or dikes would block access to the shorefront and would be objectionable to property owners. Losses at only a few locations, such as Providence, along the 250 miles of shoreline of the bay would warrant the high costs of such works, which are likely to cost in excess of $500 per linear foot, exclusive of pumping stations, provision for storm water drainage and gated openings for highways and railroads. At Providence, the high valuation of the area, the long history of disastrous flooding and the relatively narrow width of the Providence River indicate construction of a barrier across the river as a local protection measure. A barrier at Fox Point, Providence, is described in para=- graph 57. 3h Bia Business district of Providence during Hurricane "Carol" (August 1954). Millions of dollars in merchandise was lost. Foundation damage to the Howard Building in the center was a major reason for condemning this pduilding, which is being replaced by a modern, flood-proof structure. Photo by Tony Petre - si cio rz. Pe a a ie A a iit. ih sa “ sith a " tw SY ignapnyrs” oh ut Peg ideleniali (3) Protection against wave action by breakwaters. In areas susceptible to heavy wave attack, both during normal and hurricane conditions, breakwaters may be required to protect small craft and shorefront property against wave action. Studies of breakwaters have been requested for the protection of Bristol Harbor, an area highly vulnerable to wave attack. (4) Protection against erosion by low walls and bulkheads. Flood waters and wave action cause widespread erosion of exposed shores. Many owners of shorefront properties have constructed concrete walls or bulkheads to protect against erosion by waves and storms. These structures, costing as much as $100 per linear foot, are subject to overtopping during major hurricanes, necessit- ating costly repair or rebuilding. Although low walls and bulkheads are highly practical for individual shorefront properties, in no sense can they provide adequate protection against tidal flooding. d. Large-scale tidal flood barriers. A barrier, or series of barriers, stretching across such an indentation as Narragansett Bay, would protect the entire area above itself. Such a structure, if gated, could be designed to entirely prevent the entry of the tidal surge into the protected area; or, if provided with properly designed openings and placed below a sufficiently large area of water, would so restrict the entrance of the tidal surge as to reduce flood tides far below damage levels. The practicability of large-scale barriers of this kind depends upon extremely complex requirements of length, depth, tidal and current conditions, and the needs of navigation. The narrow passages and openings in Narragansett Bay provide a variety of natural sites for such barriers. 35 53. THE HURRICANE FLOOD PROBLEM The engineering problem of hurricane flood protection in Narra-= gansett Bay is one of selecting a feasible structure or combination of structures which will provide economically justifiable protection for as large a part of the bay's 250 mile shoreline as vracticable, with a minimum cisruption of existing or potential navigational, industrial and commercial, residential and other interests in the area. Review of the possible alternative methods of hurricane tidal flood control in the area indicates that while, at first glance, indivicual structures at the most seriously affected localities might appear most economically justified, the cost of these structures tends to be prohibitive, or their effectiveness doubtful. Since, at best, local structures such as dikes, walls, breakwaters, bulkheads, or small barriers can protect only a few miles of shoreline, the tidal flood damages which they prevent are greatly exceeded by their costs, except in limited areas of very high concentration and valua- tion of property, as in Providence. Conversely, although the costs of large-scale barriers are very high, the reduction in damages accruing te them tends to make them economically justifiable be- cause of the great length of shoreline which a single barrier, or series of inter-related barriers, will protect. Since nearly two-thirds of the very heavy hurricane tidal flood damages incurred in Narragansett Bay are distributed over a variety of localities; exclusive of Providence, along the nearly 250 miles of shoreline, it is clear that large-scale barriers will tend to be more economically justified than local protective structures, In view of this, the engineering problem of protection resolves itself into one of determining that barrier site and design or combination of barrier sites and designs which is most practicable from an engi- neering noint of view, and which will offer economically justifiable protection for the maximum area, Sh. STUDIES OF ALTERNATIVE PARZIER, PLANS Preliminary studies were made of the 15 plans proposed by local interests, and listed in paragraph 9. All of these plans are essen- tially for tidal flood barriers at various sites within the bay. After studies of these proposals, the following general considerations governing the selection of sites and designs of tidal flood barriers in Narragansett Bay were developed. a. Considerations governing selection of barrier sites. It is self-evident, of course, that the selection of barrier sites will be governed by considerations of necessary length, water depth, 36 and foundation conditions. Certain sites otherwise desirable will prove impracticable because of unsatisfactory foundation conditions; at other sites, excessive lengths or depths may render benefit-cost ratios substantially less favorable, or vrohibitive. Several other factors, however, constitute major considerations in barrier site selection. Among these the most significant are (1) the navigational requirements of vessel traffic within the bay and within the Providence River; (2) the necessity of adequate provision for tidal circulation and the discharge of fresh-water drainages; (3) problems created by build-up of the tidal flood level in the area below a barrier; and (4) fetch above the barrier in which water levels and waves may in- crease to damaging elevations. (1) Navigational requirements, Except for very important special requirements for Naval craft, which must be pro-= vided witn adequate navigational openings in any proposed barrier in the Lower Bay, navigational requirements present no problem at either extreme of the bay. A barrier placed at the head of navi- ’ gation, of course, presents no requirement for navigational openings. ' In the Lower Bay, ungated navigational ovenings of wholly adequate width for all present or prospective commercial vessel traffic can be provided while still admitting such a small percentage of the tidal surge as would create only a slight rise over the 120-square- mile area of the bay. A barrier placed below the confluence of the Blackstone and Providence Rivers, however, would have to be provided with watertight navigation gates which could be closed in > time of a hurricane warning. (2) Tidal circulation and fresh-water discharge. A barrier must be so designed as to provide, either by openings or sluice gates, for adequate tidal circulation to prevent pollution and the passage of interior fresh-water drainage. Barriers placed in the mid-bay or lower bay present no problem in this respect, since tidal circulation would not be adversely affected and the water area above the barrier would be sufficiently large to absorb all fresh-water drainage with only a few inches rise. A completely closed barrier at the head of navigation would present no serious problem, inasmuch as sluice gates would be adequate to provide tidal circulation and fresh-water drainage from the Woonasquatucket and Moshassuck Rivers under normal conditions, and pumping stations could be provided to take over when the sluice gates would be closed ‘ during a hurricane alert. Barriers located below the confluence of the Providence and Blackstone Rivers, however, would have to be provided with pumping stations adequate to meet a peak flood flow of 30,000 cubic feet per second from the Blackstone River drainage area, and would therefore require unusual pumping equipment and electrical power. 37 (3) Build-up. Wydrauwlic model tests have demonstrated that a barrier ccnstructed across Narragansett bay to hlock a storm surge wovld create some tuild-up, or increase in the water level below the Darrier, This bhuild-un cepencs mainly on the relative areas above and below the barrier. Jieasurenents showed that build- up increases from a negligitle amount at the head of the Providence River to a maximum of 2 to 3 feet in the iiddle Bay and falls off to about 0.5 foot near Newport. (4) Local wind and wave effects. A barrier that will effectively block ocean waves and hurricane tidal surges may not pro- vide complete vrotection for all damage areas within the bay. As the fetch ahove the barrier increases, the reduced waves grow in magnitude, and the wind drives the shallow bay and river waters to higher levels. Waves generated in the 25-mile length of Narragansett Bay may reach a height of € feet from crest to trough. The wind effect in the length of the bay, depressing levels near the mouth and increasing levels at the head of the bay, is 3 to h feet, depvending on wind direction and duration. This tipping of the water surface is greatest in the Upper =ay where waters are shallow. Appendix B contains a more detailed discussione b. Alternative plans of protection. All proposed barrier sites were reviewed in the lisht of these considerations. four alternative vlans for tidal flood barriers were selected as offering the best possibilities for protecting the Narragansett Bay area. A brief description of each follows: (1) Lower Bay barrier plan, A plan for rock-fill barriers, with navigational openings, across each of the three en- trances to Narragansett bay - an East barrier across the East Passage, a West barrier across the West Passage, and a barrier across the head of the Sakonnet River at Tiverton. This olan would provide general protection for the Narragansett Bay area, preventing more than 90 percent of the $120,000,000 damages which the September 1938 hurricane tidal flood would cost today. Dimensions of the navi- gational onenings through each of the barriers were desisned to achieve a halance between effective vrotection and the requirements of navigation, and to permit normal tidal flow in and out of the bay without setting up violent currents -round the openings. Con- struction would ranze hetween $69,000,000 and $109,900,000, depending on the uccessity for additional features for pollution control, fish an¢ wildlife and provision for settlement. 38 (2) liddle Bay barrier plan. a plan for three rock= fill barriers, with navigational ovenings, across the West Passage south cf Greemwich bay, across the sast Passage south of liount iiope Bay, and across the head of the Sakonnet Niver at Tiverton. This plan would protect all of Upoer Narragansett Bay, including liount Hope Bay, and would »revent about 75 percent of tre damages which the September 1938 hurricane would cause today. The water surface behind the barriers would be large encugh to cGispense with the need for pumping of fresh-water drainage. Since the build-up is a maximum in the tiiddle Bay, the barriers would produce more severe flood con- ditions in the areas below than would occur with no barriers. These barriers would cost approximately $70,000,000. (3) Fields Point barrier nlan. A plan for a rock= and earth-fill dam at Fields Point, Providence, across the Providence River, with a pumping station and gate for navigation. This dam would provide protection for all of Providence and a major part of East Providence at a cost of about $8,000,000, and would prevent about 50 percent of the damages the September 1938 flood would cause today. Pumping of river drainage would be necessary. Build-up of about 0.8 foot below the barrier would increase flooding along both banks of the lower Providence River and in the liiddle Bay. (4) Fox Point barrier plan. A plan for a concrete dam at Fox Point, Providence, across the Providence River, with a pumping station and sluice gates for tidal interchange. This plan would provide complete protection for the center of Providence at a cost of about $16,500,000. Although only a very small area would be protected, it is an area which accounts for about 35 percent of the total flood damages in the Narragansett Bay area. Navigation gates would not be required since the site is close to the head of navigation. Since the build-up below this barrier would be negli- gible, no significant increase in flooding would occur below it. 39 55. SELECTION OF A PLAN OF PROTECTION As indicated in paragraph 53, preliminary study indicated that tidal flood barriers offered more effective and economically justifiable protection for Narragansett Bay than individual local protective structures. Analysis of the four barrier sites selected for complete study on the basis of preliminary investigations serves to eliminate all potential sites between the confluence of the Blackstone and Providence Rivers and the Lower Bay. As indi- cated in paragraph 5) and again in paragraphs 5b (2) and (3), build-up, which increased from a negligible amount at the head of the Providence River to a maximum of between 2 and 3 feet in the Middle Bay, after which it decreases to about 0.5 foot at Newport, would cause a seriously damaging increase in the tidal flood levels below the barrier sites, either for the Fields Point location or for the considered Middle Bay location. Similar problems would clearly obtain for any proposed intermediate points. In addition, as noted in paragraph 5), the Fields Point site, or any other below the confluence of the Providence and Blackstone Rivers, would radically increase construction costs by reason of the very heavy pumping facilities necessary to discharge the flood flows of the Blackstone River. In addition to these considerations, however, a barrier located in the Providence area, and designed to provide local protection to the city, will eliminate about 35 percent of damages incurred in the entire Narragansett Bay area, leaving virtually the whole bay, including extensive Naval installations, with no protection. Conversely, Lower Bay barriers, although they will overwhelmingly reduce damages throughout the majority of the shoreline, will not provide satisfactory protection for Providence and the Upper Bay area inasmuch as the 25-mile fetch up the Bay will allow hurricane winds to generate damaging storm waves with high levels at the head of the bay. In view of this, it is considered that both barriers are necessary to provide a satisfactory plan for the over-all protection of Narragansett Bay against hurricane tidal flooding. Consideration was therefore given to specific locations for the Fox Point and Lower Bay barriers. a. Fox Point barrier. In the 0.8 mile of the Providence River between the head of navigation and the confluence of the Providence and Blackstone Rivers, there would be no significant difference in pumping requirements, construction costs, or build-up below the barrier. The Fox Point site, therefore, was selected as being farthest downstream, and hence, protecting the greatest area of the center of Providence. A barrier at ite) Fox Point would give the highest ratio of hurricane protection for expended money of any single site in the bay. It would completely protect downtown Providence, including the South Street and Manchester Street steam-electric plants of the Narragansett Electric Company. b. Lower Bay barriers. The most practicable sites in the Lower Bay are in the three narrow entrances to the Bay. For a closure of the Hast Passage at the mouth of the Bay there is little choice among alternative sites, since the narrowest reach, off Bull Point opposite Newport, is only about one mile long. In this reach, deep waters, up to 165 feet deep, cannot be avoided. The site selected for the East barrier after careful study is about 2,500 feet southwest of the 5-degree turn in the navization channel of Bull Point. ‘his, more than any other alternative site, would facilitate passage of Naval and commercial vessels. After study of five alternative barrier sites in the West Passage in a 3-mile reach extending from the Jamestown Bridge south to Bonnet Shores, a site about 600 feet souta of the Jamestown Bridge was selected. Although barriers farther south in the west Passazte would protect a larger area, the Jamestown Bridge site was chosen to take advantage of better foundation conditions, with consecuent need for smaller quantities of rock in construction, and to combine the opening in the barrier with the 600-foot navigatioral opening in the existing bridge Span. In similar fashion, various sites were considered to close off the head of the Sakonnet ttiver. A site at tne existinz stone bridge at Tiverton, connecting Tiverton and the Island Park area in Portsmouth, was selected as providirs protection to the greatest part of developed property in the immediate area, at the minimum construction cost. hl HURRICANE FLOOD CONTROL PLAN 56. GENERAL The plan selected for the protection of Narragansett Bay against hurricane tidal floodins consists of (1) a barrier located at Fox Foint on the Providence River, designed to pro- vide protection for the greatest vracticable area of the center of Providence; and (2) a series of Lower Bay barriers, comprising the east, west, and Tiverton Barriers, all provided with naviga- tion openines, designed for the general protection of Narragansett Bay. 57. FOX POINT BARRIER a. General description. This structure, about 1,100 feet long, would be 3 concrete gravity dam across the Providence River in Frovidence, from Henderson Street on the west bank to Fox Foint on the east bank (see Plates 3 and). It would include four sluice gates for normal river flow, and a pumping station for passing river flow under flood conditions. Reinforced concrete land walls at eithcr end would tie into high ground on Blackstone Street on the west end and Benefit Street on the east end. The four sluice zates, each 20 feet wide by 2h feet high, would be of a drop type, closing by gravity when released, to prevent entry of flood waters from the bay. They would be capable of discharg- ing all river flow, including full flood runoff, at times of no hurricane surge. The concrete pumphouse would contain five large pumps capable of discharging storm water drainage and river flow through the barrier when the, sluice gates would be closed to a tidal surge. An inlet structure with control gate and sheet piling canal, at the west end of the barrier, would provide about 1,300 cubic feet per second of cooling water for generating sta- tions of the Narragansett Electric Company. b. Geology. The Providence River at Fox Point is shallow and underlain by organic silt up to 15 feet in depth, except in dredged areas, Below the silt are layers of sand and silt, with some gravel, having a total thickness of 50 to 70 feet. Below this is elecial till, slopins gently to the west, ata depth varying from about 82 feet below mean sea level at Fox Point to about 115 feet below mean sea level near the west bank. Firm beering would be furnished by a penetration of foundation piles into this glacial till. For more detailed geological in- formation see Flate hand Appendix E. L2 c. Design (1) Layout. Various alignments of the Fox Foint 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 Company, and would tie in best with any proposed future wharfage or highway use. A layout with the pump- ing station on the west end of the barrier was considered, but the proposed layout 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 types of construction were considered, and a detailed design and cost compari.son 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. ; (4) 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 surge in the bay, the pumps could discharge the full runoff by reducing the differential head. This would be accomplished by allowing the fresh weter 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 hich water line. At the time of a hurricane surge, both the sluice sates and the cooling water intake through the barrier would be closed. The cooling water would be taken from and later discharged into the fresh water pool, without increasing the pumping requirements. 43 58. LOWER BAY BARRIERS a. General. The Lower Bay barriers described below are based on preliminary studies. Completion of detailed design studies that would prove satisfactory to all interests must await the results of furtner studies of the effects of the barriers on present conditions within the bay, principally on navigation, pollution and fisneries. The final plan may differ from the plan erein described in providing for larger navigational openings,an the West barrier, and the addition of navigation and sluice gates. b. Hast barrier (1) Description. This would be a massive stone structure extending from Conanicut Island 3,200 feet to Newport Neck (see Plate 5). It would have a quarry-run stone core, capped and faced with heavy derrick stones to a depth of 20 feet below mean sea level. Tne top would be 20 feet in width, at an elevation of 22 feet above mean sea level. With sides Sloping one vertical on two horizontal the maximum base width of the structure would be more than 700 feet. The barrier would be oriented at right angles to the existing navigation channel, and a navigation opening 1,000 feet wide and 50 feet deep at mean low water would be centered upon this channel. (2) Geology. Tne East Passage of Narragansett Bay at the barrier site occupies a deep trough with water depths reaching 160 feet below m.s.1. Seismic indications are that bedrock lies at a depth of 00 or more feet below.m.s.l. The character of the materials overiying bedrock could not be determined by the seismic method because velocity determinations about equalled that of water. The assumption that fine-grained materials comparable to those found elsewhere in the bay exist at the site has led to the adoption of large settlement factors. (3) Design. In view of the huge quantities of fill necessary, the problems of placing it in deep water, and the probability of violent wave attack, rock fill would appear to be mandatory for the Hast barrier. Guarry-run rock would be adequate for the core, but the need for protection against wave action would require that the top and upper sides be protected with derrick stones of 20 ton minimum size. Complete protection against the 25-foot waves that could occur at the Hast barrier might require even larger stones. [rounoyD Jueuidojeaeq pues] spouy Aq 0104ug *(yseq) 2U3tI ay} UO WUIOd xO 0} (iseMmM) JJ2AT FU} UO J901}]G UOSIApUaH WOIJ TAATY BOUSpPTAOId Ssodoe Aatiteg yulod xO J JO 3431S YAIMUYVA LNIOd XO 4 oe Se An hot 45) oe ‘ + deer eee *sutuado uotjestAeu 4Oo;- d ae 17831 ¥-000 ‘T & YIM y20dma } UMOJSAWeF WOIJ JUIPUTJXO Weep [[-YAIOI & 9q p[NoMm Totiieg sty, ‘“Ietiieg yseq jo she @ LSV3 be. Sie. ho) ‘ 2 8 ue ce. West barrier. (1) Deseription. This structure, 7,100 feet long, of the same general type as the East barrier, would cross the West Passage about 600 feet south of the Jamestown Bridge (see Plate 6), A navigation opening 00 feet wide and LO feet deep at mean 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 hOO feet west of the ship channel, Materials in the depression are fine-grained below an elevation of 40 feet below m.s.1. 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.1. (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, although 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) Deseription. This structure would consist of an earth-and-rock fill dike along the shorelines of the Island rark and Tiverton areas at the head of the Sakonnet River, and a crossing at the Old Stone Bridge between Island Park and Tiverton (see Plate 7). The total length would be 9,425 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 meer low water, would be provided which would be closed during hurricanes by a pair of sector gates, The existing town beaches would be maintained on the seaward side of the dikes, with access ramps provided. u5 (2) Geology. All materials with the exception of 5 to 10 feet of surficial orgenic silts ir the vicinity of the ship channel are granuler, ranging from fine sand to gravel. Bedrock lies at about 00 feet below m.s.l., but outcrops near the east abutment of the barrier (see Appendix E). (3) Design. The major part of the Tiverton barrier is above mean sea level, and therefore an earth-and-reck-fill structure with the slopes protected with placed rock would give the necessary stability at greater economy than rock fill. The position of the barrier, about 11 miles above the mouth of the Sakonnet River, would result in a much less severe wave condition than at the East and west barriers, and a top eleva- tion of 20 feet above mean sea level has been selected. f. Hydraulic and hydrologic considerations. The design of the Lower Bay barriers was based on criteria and preliminary studies as follows: (1) The design tidal flood of 12.8 feet above mean sea level at the mouth of the bay. This was based on initial studies of maximum winds by the U. S. Weather bureau, and of tidal surges by the Beach Erosion Board and Texas A & M Research Foundation. (2) Build-up in the flood tide levels below the East and West barriers at the mouth of the bay of approximately 0.5 foot as determined from hydraulic model tests. The build-up south of the Tiverton barrier is more than 2 feet. (3) The design wave height of 25 and 20 feet at the East and west barriers from crest to trough, derived by the Beach Erosion Board and substantially confirmed by observations of the Narragansett Marine Laboratory. (4) Wave run-up on the structures above the design tidal flood would result in overtopping of the Hast and West barriers by 6 feet or more. Preliminary studies indicated it was impracticable to design the structures sufficiently high to avoid overtopping; the volume of water carried into the bay could be absorbed by the 120 square-mile drainage area of the bay with a rise of less than 0.3 foot. Further study of slopes of structures and stone sizes is required to assure design of a stable structure. L6 Ee Rae We eee Vee ion opening. Photo by Providence Journal Co, co ee o Lov) (ss) wn n he} QO, ~~ n Cb) > () pe} ~ (a) i/3) (e} & (5) Gy Gs} ue} ee Ho “A eH ’ a4 ie) [e) H (>) o a Mo) = 3 {e) 3 is) o od hi Lo o fsa) n co te} 600 feet south of the Jamestown Bridge with a 600-foot navigat Site of West Barrier. "OD [euinos sduaeptaoig Aq oj0Ug ‘adplIg 9UOJS PIO 3 3}eS UOTJEDTALU JOOJ-QOT © UJIM SP2Ie UOJIOATL pue YIVq Pues] JO soeuty -a10ys suoTe 2AIp [[Y-YoI pue yive ue eq pfmnom Tatiieg sty, ‘“1eatiieg uojIaATy jo aig : er : We NS Cre wm ia ” ae: : aS : bo . ere 70% ee fj Me, 3 wave NOLUSAIL (5) Unusually high tides are likely to occur in advance of a hurricane surge, as they did in September 1938, causing some inflow and a small rise of the bay in advance of the hurricane surge. (6) Inflow of hurricane waters through the navigation openings was based on model tests. Further testing would be desirable to determine the most effective shape of the openings and distance across the sill normal to the opening. (7) Design streamflow of 8,000 cubic feet per second (fresh-water runoff) would result in an increase of approximately 0.3 foot in the level of the bay. (8) The rise in water level from Newport to Providence (wind setup) as a result of design wind blowing across the 25-mile fetch is estimated at 3.1 feet but would vary widely with wind direction and intensity. (9) Emptying of the bay to normal levels would occur rapidly after a hurricane has passed. The northwest winds which follow after passage of the storm center would very likely speed this up. Since the waters of the bay would be tipped upwards to the north it is likely that the water will rock back towards the barriers at the mouth. The rise in water level likely to occur in the Lower Bay would be small because of the damping action of the islands and the deep water in the lower end of the bay above the barriers. g- Navigation openings. These are a key to effective design of the Lower Bay barriers. The navigation openings were selected with a view to: (1) Fixing the openings small enough to effectively restrict the entrance of hurricane surges and provide a reasonable degree of protection in the bay as a whole. (2) Provide openings of large enough width and depth for the passage of commercial and Naval vessels, without creating excessively fast currents under normal conditions. 7 (3) Provide openings large enough to prevent adverse effects on water quality, marine life and normal uses of the bay. 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: 0-foot depth and 400-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 would rise to eleva- tions of 4.8 feet above mean sea level at Newport and 8.9 feet above mean sea level at Providence. Substantially complete 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 74. 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 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 exposed to a tidal surge of 13 feet and ocean waves of 25 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-way would be necessary, but materials could be obtained from existing sources, and relocations would be relatively slight. 8 The Lower Bay barriers would require one or more new quarries and rights-of-way to the water for barging or to the site for end dumping. At the west ena of the West barrier, a number of small beach houses would require relocation. The east end of the East barrier would tie into higher ground at one of the large estates in Newport. At the Conanicut Island ends of both barriers, and for the land wall on the island, lands and rights-of-way would be required. The Tiverton barrier would require shorefront easements, rights- of-way and a few relocations. It is easily accessible from both ends. 60. OPERATION AND MALNTENANCE ae Fox Point barrier. The Fox Point barrier would ordinarily require no operation and the sluice gates would be left open for river flow and tidal flushing. During the hurricane season, however, maintenance personnel would stand by. The sluice gates and cooling water intake gate could be closed very quickly, nence, their closure would not be necessary until a relatively late stage of the hurricane warning, but preferably at a low tide. Upon the close approach of a hurricane, the gates would be closed, and the fresh water pool kept low by pumping. Maintenance of the pumps and motors within the pumping station would necessitate periodic testing, involving running all motors and pumps for a short time and checking performance. b. Lower Bay barriers. The East and West barriers as presently considered would require no operation. Maintenance would be limited to replacing stone dislodged by wave action, and maintaining the quarry as a source of rock fill. The Tiverton barrier would require operation of the sector gates. These gates would be closed before the hurricane danger became acute, and would be left closed until the danger had passed. Therefore, periodic testing of the gates and operating machinery and ordinary maintenance of embankment, concrete features, and equipment would constitute the chief operation requirements. 61. HIGHWAY CROSSINGS UTILIZING BARRIERS a. Fox Point barrier. The design of the Fox Point barrier is adaptable to possible future use as a highway crossing, and access to and across it is a feature of the present plans. 49 b. Lower Bay barriers. The size of the navigation opening and the vertical clearance required would make a highway crossing of the Lower Bay barriers expensive. Such a crossing at the Tiverton barrier would not be necessary, because of a newly constructed highway bridge less than one mile upstream. 62. DEGREZ OF PROTECTION The Fox Point barrier, as the first unit of the plan to be constructed, would provide full protection for the center of Providence. The Lower say barriers, to be constructed later, would afford general protection to the bay and practically eliminate high-water damage from floods equal to those of 1938 and 195), although some wave damage would remain, particularly in the upper bay area. However, the degree of protection pro- vided by the Lower Bay barriers will depend on the dimensions of the navigation openings, which are subject to adjustment in final design studies. Tne degree of protection which would be provided by each unit of the plan is set forth in further detail below: a. Protection by Fox Point barrier. At the time of a hurricane warning, sluice gates in the barrier would be closed as near to low tide as practicable and pumps operated to maintain the pool level above the barrier below mean sea level. In the event of the combination of the design stream flow from the Woonasquatucket and Moshassuck Rivers coincident with the design tidal flooding from the bay, a very unlikely occurrence, the pool level might rise as high as 3 feet above mean sea level, which is well below the zero damage elevation of 6.7 feet above mean sea level. b. Protection by Lower Bay barriers. The effectiveness of the Lower Bay barriers in reducing hurricane tide levels has been based mainly on the data provided by the hydraulic model of Narragansett Bay constructed at the waterways &xperiment Station in Vicksburg, Mississippi. Using prototype data from hurricanes of record, the model has reproduced both normal and hurricane tides with and without barriers in place. In the model, the Narragansett Bay area has been reproduced to a horizontal scale of 1 to 1,005 and a vertical scale of 1 to 100. Movement of the tides are reproduced on a time scale of 1 to 100 so that the normal astronomical tidal cycle of 12.) hours in the bay is reproduced in about 7.5 minutes. A tide generator is used to Simulate normal ocean tides, the rise and fall of water levels being measured at gaging stations at various points in the model. Similarly, hurricane surges are reproduced by a large wave machine and the tidal surge can thus be superimposed on the astronomical tide. Results of the model were adjusted for wind effects in the bay (see Appendix B). The model tests have shown that with a surge equal to that which occurred during the hurricane of September 1938, Lower Bay barriers would reduce the still-water level at Providence by 5 feet, from an elevation of 15.7 feet above mean sea level to an elevation of 7.7 feet. At Newport, the level would be reduced by 7. feet from the observed level of 11.0 feet above mean sea level to an elevation of 3.6 feet. Plates 8 and 9 show maximum tidal levels that actually occurred in the area during the 1938 hurricane and the reduced levels that would occur with the Lower Bay barriers in place. With a design flood, the still- water levels would be reduced by 3 to 10 feet. The reduction in hurricane tide levels with the plan of protection in effect is shown in Table for key locations in the bay. TABLE ) REDUCED FLOOD LEVELS WITH PLAN IN EFF scCT NARRAGANSETT BAY AREA Experienced Reduced Locality Flood Level Flood Level Reduction Sept 0 Sept ° Sept e 1938 Design 1938 Design 1938 Design Flood Flood Flood Flood Flood flood Providence [See Pega Tes Ona) PeZr0()P 15. 7(D hr y527) 7.72) 8.9(2) 8.02) 9.8(2) Bristol and 13.6 Woyath ey? 5.9 8.9 10.2 Hast Greenwich rall River 13.8 16.3 5.1 6.3 8.7 10.9 and Somerset Newport 11.9 113/09 BP 3R5 4.8 7.4 8.2 Notes: Elevations are in feet above mean sea level. (1) Above Fox Point barrier (2) Directly below Sox Point barrier mil 63. EFFECTS SF THE PLAN ON NORMAL CONDITIONS IN BAY a. Fox Point barrier. The Fox Point barrier would be constructed close to the head of navigation in Providence and would contain no navigation openings. About 700 feet of wharf Space for commercial navigation could be provided at the barrier, wiich would replace existing wharfage used by a small amount of commercial shipping above Fox Point and provide additional wharfage for the port of Providence. Under non- hurricane conditions, the sluice gates of the Fox Point barrier would provide for free movement of tidal flow and unrestricted circulation througn the barrier. The tidal range would be unaffected in the 0-acre area above the barrier and no addi- tional pollution problem would be created. During a hurricane alert, when the sluice gates would be closed to prevent tidal flooding of the area behind the dam, runoff from the Woonasqua- tucket and Mosnassuck givers, plus storm sewage from the city of Providence, would be pumped through the dam. As fish and wildlife values and recreational values are non-existent above Fox Point, the barrier would have no effect on these. The design provides for continuing the supply of 1,300 cubic feet per second of cooling water to the plants of the Narragansett Electric Company. The cooling water drawn from below the barrier would be discharged into the pool above the barrier, thus providing a discharge through the sluice gates considerably in excess of the freshwater flows from the rivers. b. Lower Bay barriers. Barriers designed for the Lower Bay to orovide protection against hurricane tidal flooding must of necessity restrict tne entrance of the tidal surge so as to lower the flood tide level below the point where significant damages are incurred. Such structures will restrict the tidal range and cur- rents within the bay, with possible long range effects on tempera- ture, salinity, flusning and important related matters, such as navigation, pollution and fisheries. Extensive research, model tests and studies of these complex matters would be required for a satisfactory final design. The preliminary studies of these effects are discussed below. (1) Basic studies. The present conditions in the bay were determined from available data of the U. S. Coast and Geodetic Survey and a special hydrographic survey by the Narragansett Marine Laboratory of the University of Rhode Island. Regular observations of the latter extended over a period of 9 months and provided essential information on temperatures, salinities, currents and circulation, and bottom conditions. Preliminary estimates of the effects of the Lower Bay barriers on these conditions were made from hydraulic model tests and studies by the Narragansett Marine Laboratory and other agencies, as described below: (2) Tidal range and currents. Model tests have shown that the Lower Bay barriers would decrease the tidal range by approximately one-third. Mean high tide elevation would be lowered about 0.8 foot and mean low tide elevation would be raised an equal amount. Tidal currents would probably be reduced about 30 percent, excent in the navigation openings as noted below. The distribution of normal tidal currents and their direction would be unaffected. The effect of the reduction in tidal range on naviga- tion is discussed below. (3) Navigation. While the reduction in tidal range would not materially affect the low-water deptn of the dredged navigation channels it would affect the depth available in the Upper Bay for navigation and berthing of the largest commercial vessels whicn depend on high tide. This matter may be resolved by sluice gates in the barriers which would eliminate most of the reduction in tidal range. At the time a final decision is reached on the size of the navigation openings, it would be possible to determine whether the problem of ship clearance is serious enough to warrant modifying the barriers by introducing sluice gates. At the openings in the barriers maximum flood and ebb currents between | and 5 knots could be expected. This would adversely affect navigation, particulariy small boats of low engine power. For comparison, currents through the Cape Cod Canal range from 3 to 6 knots and at the entrance to Long Island Sound currents range from 3.8 to 5.6 knots. The navigation openings referred to mean low water of 1,000-foot width by 50-foot depth in the East barrier and hOO0-foot width by hO-foot depth in the West barrier, are con- Sidered by the Navy to be inadequate to provide the requisite margin of safety for Naval use under all circumstances. Negotia- tions are in progress with the Navy on dimensions that will meet their requirements and at the sam time retain a high degree of protection in the design. (4) Temperatures and salinity. Preliminary studies indicate that the effect of the barriers on water temperatures within the bay would be negligible, amounting to no more than 0.5°F. Normal salinity ranges from 18 parts per thousand at De Providence to 32 parts per thousand at Beavertail Point. Due to the reduction in tidal range that would result from the barriers, the salinity within the bay would be reduced by about 1 to 3 parts per thousand. (5) Pollution and fisheries. Effects of the Lower Bay barriers on pollution and fisheries are undetermined. Their evaluation is a difficult problem involving intimate knowledge of the present physical, chemical and biological makeup and balance in the bay and the new balance resulting from the barriers. Analytical studies are in progress by the U. S. Public Health Service and U. S. Fish and Wildlife Service. In conjunction with these studies, additional tests are in progress using the model at tne Waterways Experiment Station, both with and without the barriers, of the salinity regimen and distribution, flushing action and dilution of wastes, sedimentation patterns and rates, and temperature range and distribution in Narragansett Bay. (6) Beach erosion. Detailed information concerning beach erosion in the area above the Lower Bay barriers of Narragansett Bay is not available. It is known, however, that beach erosion problems exist along sections of the shore in Warwick and Jamestown and possibly in other areas. The Lower Bay barriers are not expected to have any harmful effects as far as beach erosion is concerned. On the contrary, they would have definite beneficial effects by reducing wave attack behind the barriers. 64. ADDITIONAL STUDIES OF LOWER BAY BARRIERS The combination of structures which comprise the Lower Bay barrier plan is not one that can be built immediately. The scope of the problem is such that further expensive studies and research investigations are required. These studies include the following: ae Design flood. (1) Determination of the maximum probable hurricme as a check on the selected design wind field. (2) More complete investigations of tidal surges for effects of three different types of storms. (a) the fast moving storm, which gives a high sharp crest 5h (b) the slower moving storm, which gives a lower crest but a greater volume, and (c) the stalled type. b. Negotiations with the Navy. (1) Decisions on the minimum size of navigation openings acceptable to the Navy in the light of protection requirements and strategic considerations. (2) Investigation of the need for traffic control and construction and maintenance procedures. c. Model tests and analytical studies. (1) Additional tests of barriers under flood condi- tions with emphasis on (a) openings desired by the Navy; (b) the most effective shape of the barriers; and (c) surges having a lower flood crest but greater volume than the design flood. (2) Tests on sedimentation, tidal flushing and salinity. (3) Analytical studies of termperature changes, based upon the salinity tests in the model. d. Foundation investigations. Deep water borings and sampling at tne East barrier site, for correlation with the seismic explorations and for testing. Borings at the West barrier site to supplement the boring records relating to the Jamestown Bridge, 600 feet to the north. e. Pollution. Studies of flushing rates and tne effect of barriers on pollution of the bay waters. f. Fish and wildlife. (1) Completion of the inventory-type studies now in progress of existing biological conditions, and shellfish and finfish. (2) Studies of the bay as a spawning amd nursery area for oceanic fish species. (3) Studies of the tolerance of various species to Changes of termperature, salinity and the like. 2 (4) Determination of the effects of barriers on fisheries and resultant changes, if any, in navigation openings and sluice gates. g- Design studies. Completion of the studies described above is required as a part of the design studies for the Lower Bay barriers. 65. VIEWS OF LOCAL INTERESTS At the public hearings, local interests presented their views on the proposed plan of protection (see paragraph 50 and Appendix G). The views and opinions of the groups am individuals who attended the hearings are summarized as follows: a. A majority, including the Governor of Rhode Island, the Providence Hurricane Protection Committee, and the Mayors of Providence and Fall River, expressed general approval of the two- unit plan of protection, consisting of the Fox Point barrier in the Upper Bay and the East barrier West barrier and Tiverton barrier in tne Lower Bay and Sakonnet River. The Governor of Rhode Island also urged continuation of studies of the effects of the barriers on the natural resources and physical conditions within the bay. In regard to financing, he stated that the policy set forth for river flood control projects should be followed, the Federal government assuming costs of all basic construction and local interests assuming costs of all necessary rights-of-way and land acquisitions, and of maintenance. He also stated that local protection would be necessary wherever barriers by then- selves could not prevent damaging flooding of some areas. A group representing the Town of Bristol requested consideration of breakwaters in Bristol Harbor to protect against damaging waves. b. Several individuals, while endorsing the two-unit plan of protection, were concerned with the effects of the Lower Bay barriers on fish and wildlife, pollution, navigation, Naval require- ments and the physical characteristics of the bay. Others expressed opposition to the Lower Bay barriers on the grounds that taney would have adverse effects on present conditions within the bay or that their ultimate effects on present conditions could not be evaluated for several years, and proposed local protection or other methods, such as better hurricane warning systems, Federal flood insurance and individual protection measures, as alternatives. 56 ESTIiWATES OF FIRST COST 66. 11 estimates nave seen prepared on the basis of 1956 price levels, usins unit orices based on actual bic srices for Similar work in the region, with corrections to allow for the size and cnaracter of the provosed plan. The total estimated first cost of the Fox Point barrier is $16,500,000. Tables 5, 6 , and 7 summarize the principal items of first cost; detailed costs are given in Appendix F. The total estimated first cost of tne Lower Bay barriers ranzes from a lower limit of about $69 ,000,0V0 to an upper limit of about »109,009,000, denending on Naval recuirements, foundation conditions, and facilities installed for pollution control and fisneries. The lower limit mignt be maintained uncer optimum conditions, sucn as a nigh degree of foundation stability anda a minimum of further caanges in design. The upper limit allows for larger foundation settle- ment in tne Sast barrier ana includes provision for navigation gates and possible sluice gates in tne west barrier. BOTIMATES OF ANNUAL CHARGES 67. 4nnual cnarges are based on 2.5 percent interest on the investment, amortized over 2 50-year period, »lus the estimated costs of maintenance and opctration. The estimated annual charges are 732,000 for tune ox Point barricr. Annual charges for the Lover 3ay barriers ranze from -»2,5U0,000 for the lower limit of first cost to 5,167,000 for the upper limit. Tables5, 6, and 7 sumnuarize tne annual charges; a detailed sumnary is given ir Appendix F.- 57 TABLE 5 FInST COSTS AND ANNUAL CHARGES Fox Point Barrier = Providence, Rhode Island Item Federal Local Total ” FIRST COST AND INVESTHENT Construction of Barrier and Pumping Station $15, 345,000 Lands and Damages $200, 000 Electric Power Installation 835,000 Sewer and Drainage Modifications 120,000 Total First Cost $16,180,000 $320,000 Interest during Construction 40), ,000 8,000 $16 58,000 ANNUAL CHARGES $328,000 Interest on Investment $ 414,000 $ 8,000 Amortization 170,000 4,000 Estimated Tax Losses 2,000 Maintenance and Operation 134,000 Total annual charges $ 58,000 $118 , 000 58 $15 , 345,000 200 ,000 835,000 — 120,000 316,500,000 412,000 __ $16,912,000 $ 422,000 17,000 2,000 134,000 $ 732,000 TABLE 6 FIRST COSTS AND ANNUAL CHARGES Lower Bay Barriers - Narragansett Bay Estimate of Minimum Cost Federal Local Total Construction of barriers, dikes and walls $ 67,273,000 $% 1,617,000(1) $ 68,890,000 Lands and Damages - 110,000 110,000 Total First Cost $ 67,273,000 $ 1,727,000 $ 69,000,000 Interest during Construction 2,527,000 65,000 2,592,000 Total Investment $ 69,800,000 $1,792,000 $ 71,592,000 ANNUAL CHARGES Interest on Investment $ 1,742,000 $$ 45,000 $ 1,787,000 Amortization 715,000 18,000 733,000 Estimated Tax Losses Operation and Maintenance 57,000 $ 2,514,000 $ 66, 000 operation and maintenance of structures. 59 3,000 3000 000 3 57 $ 2,580,000 (1) Cash contribution to first cost in lieu of anmal FIRST COSTS AND ANNUAL CHARGES TABLE 7 Lower Bay Barriers - Narragansett Bay Estimate of Maximum Cost Item Construction of barriers, dikes and walls Lands and Damages Total first cost Interest during construction Total Investment Interest on Investment Amortization Estimated Tax Losses Maintenance and Operation Federal $ 105,203,000 $ 105, 203,000 5,260,000 $ 110,463,000 1,133,000 as 4,023,000 Local Total (1) $ 3,687,000 $ 108,890,000 $ 3,987 ,000 $ 114,450,000 ANNUAL CHARGES $ 100,000 § 41,000 3,000 $ 14,000 $ (1) Cash contribution to first cost in lieu of annual operation and maintenance of structures. ESTIMATES OF BENEFITS 68. EVALUATED TANGIBLE BENEFITS Renefits which have been evaluated for the plan include flood- damage prevention benefits and benefits from elimination of scare costs. Eenefits that may be realized from breakwaters and other measures in several localities will be presented in a future report. Average annual flood-damage prevention benefits were derived by determining the difference between annual losses under present conditions (see paragraph 45) and the losses remaining after con- struction of the projects in the plan. Annual flood-damage pre- vention benefits in the areas of the bay protected by the plan amount to $5,902,000, of which $1,697,000 would accrue to the area above the Fox Point barrier and $1,, 205, 000 to the area between the Fox Point barrier and the Lower Bay barriers. Benefits from the elimination of scare costs would amount to #98,000 annually, of which $36,000 would accrue to the area above the Fox Point barrier and %62,000 to the area between the Fox Point barrier and the Lower Bay barriers. Total annual benefits for the two-unit plan amount to $6,000,000. A recurrence during the fifty-year amortization period for the project of the flood stages produced by the three most severe hurri- canes of the past 50 years (1905-1955), those of September 1938, September 19), and August 195), and a recurrence of the flood-produc- ing storms and other hurricanes in this period, would result in a savings of $226,880,000, amounting annually to $),538,000. Including scare cost piindneien benefits, the annual savings would amount to $4,636,000. Substitution of the design storm for the hurricane of 1938 would result in a total 50-year savings of $309,960,000, or $6,199,000 annually, amounting to #6,297,000 with scare-cost benefits. Table 8 presents these recurring damages, the damages that would be prevented by the plan of protection and the damages that would remain in the bay area. These residual damages do not reflect wave action within the protected areas because available data do not permit reliable estimates of such damages. 61 Hurricane September 21, 1938 September 1h, 1sht August 31, 195); (Carol) TABLE 6 RECURRING AND PREVENTASLE TIDAL FLOOD DAMAGES (1956 Price Levels) Narragansett Bay Area Other Hurricanes and Sever’ Storms (1905-1955) Total Design Hurricane Damages Recurring Preventable Flood Damages by Pler $120, 220,000 $120,010,000 6,260,000 €6,&60,000 92,239,000 92,120,000 7,£90,000 7,890,000 $227 200,000 $226, 880,000 $203 , 960,000 £203 ,090,000 62 Residual Damages 210,000 none 110,000 None $320,000 $870, 000 69. UNEVALUATED TANGIBLE BENEFITS The planned protection of the Narragansett Bay area would result in additional important benefits which have not been monetarily evaluated. Substantial benefits would stem from the prevention of tangible damage to transient items such as vessels afloat and vehicles parked on streets or in parking lots. Benefits would also be realized from the reduction of intangible losses, including loss of life, health, and the threat to national security. Refer to Appendix D for a detailed discussion of the derivation of annual losses and benefits. 70. INTANGIBLYe BENEFITS Intangible benefits loom large in the total benefits to be derived from the construction of proposed barriers. Loss of life would be prevented. Dangers of disease arising from polluted flood waters and water supplies would be eliminated. Insecurity and worry amone the residents concerning unpre=- dictable hurricane flooding causing loss of life and property would no longer be a concern. Protection would stimulate all segments of the economy and improve the general welfare of the residents. With vital Naval interests in the area, the plan would significantly contribute to the national defense. 63 ECONOMIC JUSTIFICATION 71. BUNEFLIT-CIST COrPARISON The Fox Point barrier, the first unit to be constructed, would nave a benefit-cost ratio of 2.37 to 1.9. The benefit- cost ratio for tne Lower Hay barriers would range from 1.65 to 1.0 to 1.02 to 1.0. These ratios correspond to the range of first cost of the Lower Bay barriers from $69,000,000 to #199,090,909. Average annual benefits of the two-unit plan are estimated at 36,000,000. The benefit-cost ratio for the plan as a whole ranges from 1.22 to 1.0 to 1.81 to 1.0, as summarized in Table 9. From another viewpoint, benefits of approximately $203,000.000 that would be attributable to the two-unit plan from one design hurricane flood would more than pay for construction of the project. Of the total, $78,000,000 would accrue to the Fox Point barrier and the remaining $125,000,000 to the Lower 3ay barriers. TABLE 9 ECONOMIC DATA OF PROPOSED PLAN, NARRASANSETT BAY ARSA (1956 price levels) Average Benefit-Cost Ratio Annual Average Annual Charges Lower Upper Unit Benefits Minimum Maximum Limit Limit Fox Point 31,733,000 # 732,000 $ 732,900 2.37:1.0 2.37:1.0 Barrier Lower Bay l ,267,,000 2,580,000 l 5167 ,000 MoOPsLoO) W66Ss60 Barriers Total $6,000,000 $3,312,000 4,899,000 1.22:1.0 1.81:1.0 PROPOSED LOCAL COOPERATION 72. Officials of the State of Rhode Island at the public hearing on 1 October 1956 expressed the view that policies for Federal financing of flood control projects should be applied to hurricane flood protection projects, and have indicated their willingness to participate on this basis in paying such costs as land acquisitions, changes in local facilities and maintenance. 64 IITINW xew Aq 0j0Ud ,TOLeD,, VUeDTIINY sutai b Tainp pot ‘ ¢ s pertns50 000 000 ‘o¢ jnoqde oO} sutjunoure ‘a3 (FS61 ss0e0yy) ; eulep }e0q-T[eus AY §?d) tvolwar ya24)° Log EO gis epost: Fp Ps ins to LGIue 9 Sg) quisyte’ ¢ pa 4 acKed st prettrsro esi Bose MAT } Nay be cere tematty a : . " ~ ‘3.0; = Tee penal th Ty. . Me ¥ By ort) ih GS te ' iL. e vo a+ P “pasar ot: Live): : 7 alia 4 : gp SOD Te D Fy Krde : deine f > ote ernie aD ane ay P ‘ { ees Be be pte: i" Sic / ae sewacised 4, Tali Po Na y ED) seta , . a i) “00, ooo” Day : AD ‘ ws an Frown ia 1% estan. f pee i neo at fir nonetrichvet « Ded poo linee : y se th: Sa eae a shee mocedey ‘> Le ats. ® The Fox Point barrier, which would protect the business center of Providence, is presented as a local protection project with construction by the Federal government and operation and maintenance by the city. On this basis, local interests would be required to participate as follows: : a. Provide without cost to the United States all lands, easements and rights-of-way necessary for the construction of the project. The cost has been estimated at $200,000. b. Provide without cost to the United States all relocations of buildings and utilities, sewers and related facilities, The cost has been estimated at $120,000. c. Hold and save the United States free from damages due to the construction works. d, Maintain and operate all works after completion in accordance with regulations prescribed by the Secretary of the Army. Maintenance and operation have been estimated to be $134,000 annually, the present worth of which amounts to $3,800,000 over the 50-year amortization period, The Lower Bay barriers, consisting of the East, West and Tiverton barriers, would protect several cities and many towns in two states and also large Naval installations. Navigation, fisheries and pollution control would be affected. The project would be constructed, operated and maintained by the Federal government, Cost of operation and maintenance would be borne by local interests. Benefits would be largely general, accruing to a diversity of interests in the region. Local interests would be required to participate as follows: a. Provide without cost to the United States all lands, easenents and rights-of-way necessary for the construction of the project. The cost has been estimated at $110,000. b. Hold and save the United States free from damages due to the construction works, No cost estimete is available, but it is possible that this could be a substantial item considering interests of the fishing industry, pollution control and navigation, c. Contribute in cash to the first cost of the barriers a sum in lieu of annual operation and maintenance. This contribution is estimated to ranze from $1,617,000 to $3,687,000, depending on the final design, The annual cost of operation and maintenance 65 is estimated to range from $57,000 to $130,000. As an alternative, local interests could contract to psy amually the cost to the United States for the performance of this work. APPORTIONMENT OF COSTS AMONG INTERESTS 73. 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SNYNOddyY \ 2 a batt al Taxnimve 7 ‘ i Al ys waza} 000 '008'L$ $ } NOISNV¥D ij HLOSOHSAY a ; | wes sla n NOILVI07 dVW | AVG 1L3SNVOVENUN NOLHSIG 000'009 ‘Ib $ Aa1yyse AHNONSSRS NOLNAWSL CORPS OF ENGINEERS ecorvuent | __} | 91.__ iinet PUMPING STATION BARRIER 1 / EX nc MOT RIO ROCK FILL wT Aes J Bri" © FOX POINT BARRIER PLAN SCALE IN FEE 400 9 400 800 1200 1600 s é =e eS . + ait eunimcrom ) | oun, H x PELE : (3 “hase age ; ; ‘ ue * j 4 y ” 5 a LOCATION MAP SCALE mw MILES eer - # HURRICANE SURVEY NARRAGANSETT BAY BHODE ISLAND FOX POINT BARRIER PLAN ROVIDENCE RIVER RHODE 18L an TO ACCOMPANY REPORT DATED 15 FEB 1957 i i receipt Y fy ee (a neg t rt Re AD nciainiinne ee ea fa ee ete es ee err CORPS OF ENGINEERS x WARM wartn “oN —Saavekte enol 2) CABLES Presa ra SCALE IN FEET ° ALLENS AVE TOP OF LAND WALL V HD Original ground tine 200 HENDERSON ST e225 Stop log structure STEEL SHEET PILING CONCRETE WALL PUMPING STATION STEEL SHECT PILING 4 SLUICE GATES CONCRETE BARRIER Eb 12 5 DOWNSTREAM “COOLING WATER “INTAKE ROCK FILL Seng i — Pile cut-off El ~370 Stee! sheet piling fo EL. -60L SECTION THROUGH SLUICE GATES CONCRETE BARRIER PUMPING STATION Va Rock fill PROFILE SCALE IN FEET 20% HORIZONTAL VERTICAL 123 DOWNSTREAM S/DE 4-3 = Sheet pile — cut -otf Construction Joint Sheet pile cut-otf Fi -120 Pile cut-off rr! SECTION THROUGH CONCRETE BARRIER SCALE 500 Bt 37 = =a 50° DEC 252 | Structurol_ [f | concrete 2h 6} Congrruction Pressure relict fe slot — f 4 Litting mechanism —> DOWNSTREAM Gote open- Sheet piting U.S. ARMY 10° Stone apron 20'L Typ in vicinity of goles —pregge tine (Tre @ gotes 6 dam sect) Piles @ S'r6'cc Stagger botter pile (Tre @ gotes & gam sect) Sheet piling carried to Et -6O! IN Feet itting mechonism Structural concrete Pressure celiel Ne closed Z a Sheet pile cut-off, ex_190 opron Dredge line (See section through concremm borrier) Piles corried to firm foundation SECTION SCALE in FEET ° 10 RAILROAD Stop log storoge TOP OF LAND WALL EL 225 Stop log structure Stop log slor Sheet pile cut-off FEL -265 Tremie concrete , . . » , n- oh en Eu oe Steel sheet piling to EL.-602 THROUGH COOLING WATER INTAKE GATE SCALE IN FEET LAND SIDE ‘Structure! concrete BAY SIDE CONCRETE LANDWALL NOT TO SCALE (Typ for barrier & pumping station) VICINITY MAP SCALE IN MILES (ek he Oe Pa DOWNSTREAM SIDE } in hae with downstream ~~ -*4 2 face of dom< 125 Stop log stor ~ 9 es 4 Typical born sides 50 a Pite cul- 3 >! Sheet piling \Maies s'0€ tetirm SECTION THROUGH PUMPING STATION SCALE 20 ° 20 “o —— SSS im Peer NOTE Elevations are in feet and are relerred fo Mean Sea Level Datum CORPS OF ENGINEERS U S ARMY CFICE OF Tmt OTon (wane HURRICANE SURVEY NARRAGANSETT BAY RHODE ISLAND FOX POINT BARRIER PLAN PLAN, PROFILE & SECTIONS DEC 1956 TO ACCOMPANY REPORT DATED IS FEB. 1957 PNA-I-1002 smear 2 2 ces pete En zumabain she 18» DAs skp nd nl DEI Rag saviee : Mh wea a Le ai CORPS OF ENGINEERS ELEVATION IN FEET MSL width of Ungated Opening fo be 1/000; Depth-500 Miw — CONANICUT ISLAND f 13E eho TOP OF BARRIER £1 -5/6 MSI Approsimate Botiom on $4 -1000G 20100 30100 PROFILE ALONG & BARRIER SCALE IN FEET VERTICAL © FT ADAMS BULL POINT SCALE IN FEET 1500 ELEVATION IN FEET M.S.L ae ? - POINT OF— TREES OCEAN SIDE QUARRY RUN ROCK Approximate Bottom SECTION B-B SCALE IN FEET OCEAN SIDE Bay SIDE DERRICK STONE, 20 TON MIN, 12. QUARRY RUN ROCK Approximote Bottom SECTION AWA SCALE IN FEET U.S. ARMY acon parouat? VICINITY MAP SCALE im MILES. (ir vies TT BAY SIDE — 20. TOP OF Sith, Et -5/6 NOTES Bose mop and contour elevations are taken from a biawup of USA Quadrangle sheet No 6766 IV NE, and are recorded /n feet above Mean Sea Level Contour iatervel is 10 feet. Soundings are shown to the mearest foot ang are referred to the plane of Mean Low Water Soundings are from survey of Sept 15 fe Sept 22, 1935 Tides (referred to Mean Low water} From USC 8 GS. Chart No. 2356 Beavertall Polat Mewporr Mean High Water 3.5 teer S3.5feer Mean Sea Level 1.6 feet 6 teet CORPS OF ENGINEERS U S ARMY HURRICANE SURVEY NARRAGANSETT BAY RHODE ISLAND LOWER BAY BARRIER PLAN EAST BARRIER CONANICUT ISLAND TO NEWPORT NECK TO ACCOMPANY REPORT CRAG USOT ® DATED IS FEB. 1957 PNA-FI003 oer ims wrt (de ys» San aya may thet An deme eepariseaai a.k.a yaad op ASEM — Se so +. Cam hens ‘ne i } ee to Cee no 4 i ie. Paka The ee # “void we PORT Wp RanAAR PF eeOuA 3, a CORPS OF ENGINEERS U.S. ARMY es. , | 3 Sl ZX@ ELDRIOGE f sh "St | : a + » BARRIER 3 ” Wy Behe PASS : =a alovE ) VICINITY MAP fs a so v <9) oTCMLE IN BLES | / AGHANN Sabatier RR so ” PH fe \ EN PLAN SCALE IN FEET 500 o 500 1000 1500 2000 PLUM BEACH TOP OF BARRIER EL. 22.0: 10'x 10" CULVERT WIDTH OF UNGATED OPENING TO BE 400FT., DEPTH - 40.0MLW DERRICK STONE, 20 TON MIN., L2. OCEAN SIDE BAY SIDE: CONANICUT ISLAND s Approximate bottom SECTION A-A SCALE FEET 30 ° x0 ‘o SSS Approximate bottome ELEVATION IN FEET MSL i a = bt wu rr re = z —— =) = < > wu a a NOTE: Base map and contour elevations are taken from blow up of US A Quedrongle sheet No. 6767 tii SW and ore recorded =10+00 0400 10+00 20+00 30+00 a0+0e 30+00 60+00 70+00 B0+00 in feet above Mean Seo Level. Confour ini is ten feet Soundings are shawn fo the nearest foot ont ore refered. PROFILE ALONG ¢ BARRIER en eee Sen aera Samed deh bh hansl SCALE Ww FEET ae chart No 500 o OF! soo food! Tides (referred to Meon Low Water) from USC. & — GS chort No 236 VERT ss o so 100 ——_ Beovertail Pont ‘Newport Mean High Woter 35 teer 35 feet Meon Seo Level 16 feet 16lewt fee's 122.0 ee wisHis0 ue DERRICK STONE, 20 TOW MIN., 125 BAY SIDE CORPS OF ENGINEERS U S ARMY OCEAN SIDE BAY SIDE OEE ome mite ors START DERRICK STONE, EL ~200> ith eae aaes | eaiee HURRICANE SURVEY TOP OF - Lt Ee Soo arerurceretl| INIAIRIRUAIG AUN SE: Telia GLANS QUARRY RUN ROCK ie RHCDERISERRD. ‘ LOWER BAY BARRIER PLAN EL.-46.0- Approximate bottom WEST. BARRIER SECTION C-C SCALE IN FEET 30 ° sc 60 PLUM BEACH TO CONANIGUT ISLAND SECTION B-B SCALE IN FEET 30 3 30. = i pend [scae_as swoww TO ACCOMPANY REPORT ‘DRAWING ROMBE® PNA-I-1004 cer 2 oS DATED IS FEB. 1957 PLATE 6 et 9 epee es il : | intermittent Shrub Piontings a) Deep Rooted Gross Spes flies ~\ \ Filter Loree} PARE AVENUE —1 Selected Full a se (Groce! Ti) SECTION B—B toce Treuteg Grove) Rood 5" Cone Post for Coble Railing T Plocea Rock 1-6" Select Stone a aeleet Stone rMSL20_ ECTION F-F 4 (F ¢ FRERRD SMELL — Sh 6 a ~ JLo Catch Bosin for Storm oiong River Front Property Evixting Mouse NG +Lkcom Selected Frit Were TiN) TOP OF BARRIER |Retale for) rain SECTION C-C —= Rood Borrier oe PLAN SCALE IN FEET 200 0 200-400 —100' GATED OPENING 0 x oowl BARRIER EL. 200 ELEVATION — PROFILE OL 400-800 SCALE: io Qe og. ieee for | Porkiny Wa HILLSIDE | |= ave—|_ | Sanoqwer, A ae Earnng brage ‘aporoeen SCALE FOR ALL SECTIONS IN FEET _—— Top of Borrier*E! 20.0 Fenger Piles bet hn CORPS OF ENGINEERS U S ARMY FICE OF Tae Brett emcee ‘Sew trcaawo one soxton mash HURRICANE SURVEY NARRAGANSETT BAY RHODE ISLAND LOWER BAY BARRIER PLAN TIVERTON BARRIER a y ~_Sheainong I be lett in pioce TO ACCOMPANY REPORT DATED I5 FEB. 1957 SECTION 6=-G PNA-1-1005 smcer Sor 3 2-0 eoerome a ee ~ vat mae wg ne HOR yet ; CORPS OF ENGINEERS U.S. ARMY As sees ee UNO RE ee | PROVIDENCE —-+———— EasT PROVIDENCE ——— -|+-—- BARRINCTON BRISTOL —= PORTS MOUTH >} MIDDLE TOWN --f-— —— 0O= FOX POINT- T Pe ee | | ee = o | PRGYIDENGE ae NORTH KINGSTOWN HURRICANE FLOOD SEPTEMBER 1938 REDUCTION /N WAVE ACTION CUO ME THAIAIE | | — REDUCTION IN STILL WATER LEVELS (ORO Mm Presents IN FEET ABOVE MS._L IN FEET ABOVE M.S.L. = ELEVATION ELEVATION NOTE :- Lower Bay Barriers "FLOOD “REDUCED yt : Navigation Openings Ungated an = fost Posse 1000's 50'MLW BY BARRIERS eaten 400's«0'mcu | FOX POINT BARRIER E : COMPLETE PROTECTION 5 ‘ Se ~ : CORPS OF ENGINEER: OFFICE OF TRE Dreise0s HURRICANE SURVEY NARRAGANSETT BAY RHODE ISLAND HURRICANE FLOOD LEVELS SEPTEMBER 1938 FLOOD REDUCED BY FOX POINT AND LOWER BAY BARRIERS “Al DEC . 1956 SAP aU) Mm Wikis S f TO ACCOMPANY REPORT Deawing NUMBER DATEO IS FEB 1957 PNA-3-1000 sueatt ow 2 PLATE 8 2 BRD CORPS OF ENGINEERS U.S. ARMY +—— O= PETERS POINT = — = BERKLEY FALL RIVER + —- TIVERTON MASS. RHOCE ISLAND a E % z SWANSEA | “-WARREN os : : r IGH TON SOMERSET : oe DIG + MERSE canis ——— AQUIDNECK ISLAND ATLANTIC OCEAN 4 a3 : a oe ‘ ao | REDUCTION IN WAVE ACTION : 87 70 12 FEET IN FEET ABOVE MSL. IN FEET ABOVE M.S.L. Sa REDUCTION IN STILL WATER LEVELS TIVERTON BARRIER 8709 FEET ELEVATION ELEVATION NOTE:= Lower Boy Barriers Tiverton Borrier 100's30' Gated Opening Novigation Openings Ungoted East Borrier (000's50' M.t.w. FLOOD REDUCED All Wes! Barrier 400'x 40' MLW. BY BARRIERS : oa 7 ESTIMATED MEAN HIGH WATER HURRICANE SURVEY ESTIMATED! MEAN LOW WATER Vet wunm|MT, HOPE BAY-SAKONNET RIVER iw MASS.- RHODE ISLAND HURRICANE FLOOD LEVELS 7 SEPTEMBER 1938 FLOOD REDUCED BY LOWER BAY BARRIERS SCL AS SHOWN TO ACCOMPANY REPORT — Deane ONBER DATED '5 FEB. 1957 PNA-3-1001 Ror ade 3 PLATE 9 i eres ile beaieslebvearviiore - entirely ~ - r Lf ue rn i oy { : \j Nh ir iy at seh Big eu