Criteria for the Depths of Dredged Navigational Channels
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The National Academies Press
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1 INTRODUCTION As elaborated in succeeding chapters of this report, several considerations affect decisions about the depths of dredged navigational channels. These can be separated into two general categories, the requirements of navigation (principally the underkeel clearance required in a variety of physical conditions) and those of achieving and maintaining dredged depths, but in actuality, they must be considered together. AS noted by Kray (1973), "=is is to provide for smooth operation and to avoid costly accidents for inadequately designed channels and maneuvering areas, and an excessive cost of constructing and maintaining the overdesigned navigational facilities." Table 1 indicates the scope of concerns for navigation and maintenance in the channels of deep-draft ports and harbors--those 30 ft or more in depth.* The costs of dredging to maintain channel depths and the tonnages of trade accommodated by these channels are obviously considerable. *The U.S. Army Corps of B gineers defines deep-draft navigational projects as those 14 ft or more in depth. The concern of this study is the navigational channels of the major coastal ports and harbors--the 85 ports and harbors reached by navigational channels 30 ft or more in depth. 1-1

1-2 Table 1 Costs to maintain channels and harbors of major ports in the United States by dredging, and 1978 trade, by tonnage* Annual Average Port Depth Maintenance Cost 1978 Tonnage (in feet) (in thousands) Alaska AlabAt'~a Anchorage Harbor 35 $1,453.6 2,226,200 Mobile Harbor 40 5,303.2 17,336,800 California Humboldt Harbor & Bay 35 1,243.9 1,435,900 Stockton 30 979.8 2 ,277 ,600 Suisun Bay Channel 30 147.4 1,164,800 San Pablo Bay 35 503.1 7, 082,600 Oakland Harbor 35 1,143.3 6,232,500 Richmond Harbor 35 1,182.1 15,902,900 San Francisco Harbor 40 39.1 50,4()L,500 Los Angeles-Long Beach 45 144.0 60,780,900 Harbor San Diego Harbor 35 0 2,360,;200 Connecticut Bridgeport Harbor 35 2;24.8 3,732,600 New Haven Harbor 3S 566.9 11,323,200 New London Harbor 33 7.8 2,550,600 Delaware Florida Georgia IWW Delaware to 32 10,322.9 10,226,200 Wilmington Harbor 35 1,851.0 2,162,100 New Castle 35 1,202.2 8,278,;200 Delaware City 35 516.5 3,556,400 Charlotte Harbor 32 1,322.5 1,067,300 Canaveral Harbor 36 2,438.7 2,341,500 Panama City Harbor 32 210.0 282,900 Port St. Joe Harbor 35 167.8 326,200 Pensacola Harbor 33 633.6 1,538,600 Palm Beach Harbor 33 209.9 728,600 Jacksonville Harbor 38 3,098.7 13,119,400 Key West Harbor 30 25.7 202,600 Tampa Harbor 36 2,309.4 46,866,400 Miami Harbor 38 20.3 3,098,900 Port Everglades Harbor 42 83.7 11,929,300 Brunswick Harbor 30 3,490.5 1,259,000 Savannah Harbor 38 10,429.8 10,633,400

1-3 Annual Average Port Depth Maintenance Cost 1978 Tonnage (in feet) (in thousands) Hawaii Port Allen Harbor 35 63.7 89,300 Nawiliwili Harbor 35 535.3 765,900 Kahului Harbor 35 671.2 1,922,100 Hilo Harbor 35 352.2 1,272,700 Honolulu Harbor 45 167.7 7,140,500 Louisiana Calcasieu River & Pass 40 7,336.1 13,563,000 New Orleans 40 16,661.9 77,231,400 Baton Rouge 40 18,297.5 123,937,800 Maine Portland Harbor 35 613.4 21,964,800 Maryland Baltimore Harbor 42 2,477.6 37,074,600 & Channel Massachusetts Cape Cod Canal 32 4,096.6 12,226,600 Fall River Harbor 35 133.2 4,642,300 Boston Harbor 40 181.1 24, 700 Mississippi Gulfport Harbor 30 1,899.2 950,000 Pascagoula Harbor 38 2 ,485 .5 18 ,258,200 New Hampshire Portsmouth Harbor 35 140.7 3, 293, 300 New Jersey Camden 30 264.6 1,787,400 Gloucester 35 245.4 1,690,000 Paulsboro 40 2,522.9 17,372,800 New York Hudson River, Albany 32 1,907.5 10,440,500 New York-New Jersey 45 12 ,905 .7 119, 317 ,600 North Carolina Morehead City Harbor 40 1,969.6 2,069,400 Wilmington Harbor 38 3,041.6 7,422,800 Oregon Yaquina Bay & Harbor 32 1,379.2 668,500 Coos Bay 45 3,652.3 S,218,900 Portland 40 12,567.1 16,524,952 Astoria 40 881.7 1,159,300

1-4 Annual Average Port Depth Maintenance Cost 1978 Tonnage _ {in feet} (in thousands) Pennsylvania Penn Manor 40 1,376.6 4,041,200 Philadelphia 40 6,702.0 37,067,600 Chester 35 4.1 28,100 Marcus Hook 40 3,446.4 23,731,900 Puerto Rico Mayaguez Harbor 30 106.7 335,300 Ponce Harbor 30 77.7 911,400 San Juan Harbor 48 852.9 10,147,800 South Carolina Charleston Harbor 35 5,816.9 9,548,800 Texas Brazos Island Harbor 36 3,116.6 1,162,900 Matagorda Ship Channel 38 2,610.3 3,963,200 Freeport Harbor 36 3,590.8 18,657,400 Galveston Harbor 40 1,638.8 7,004,300 & Channel Corpus Christi 45 ~ 6,202.1 46,244,500 Sabine Ports 40 7,981.8 69,740,900 Houston 40 8,312.5 81,221,825 Texas City 40 1,954.1 23,627,800 Virginia Norfolk Harbor 45 2,801.7 25,286,900 Newport News 45 932.0 5,740,900 Washington Grays Harbor & 30 4,668.4 2,664,000 Chehalis River Vancouver 40 1,185.5 1,558,800 KalamA 40 199.6 262,500 Longview 40 4,645.5 6,108,500 Everett Harbor & 30 457.0 2,167,900 Snohomish River Bellingham Harbor 30 140.8 891,000 Seattle Harbor 34 376.5 11,357,500 Ediz Hook-Port Angeles 30 19.3 2,774,100 Tacoma Harbor 35 44.5 9,667,300 a Rounded to the nearest hundred tons *SOURCE: From U.S. Senate Committee on Environment and Public Works (1981), Report to Accompany S. 1692, National Harbors Improvement and Main- tenance Act of 1981, 97th Congress, 1st Session, pp. 29-32.

1-5 Thus, economic considerations (specifically excluded from the panel's analysis) dictate that the depth and other dimensions of a channel be minimal, but consistent with the safe passage of ships calling at the port or harbor. These ships,-over the past decade and a half, have been increasingly larger. Some examples of common ship types and their-design data are given in Table 2. The hydrodynamic forces and effects experienced by these vessels in navigational channels differ markedly from those experienced in the open ocean. The draft and attitude of a vessel change continuously while it is under way in a navigational channel, owing to the combined effects of natural and ship-generated forces and the dimensions and layout of the channel. Vertical excursions present the danger that the vessel may ground or strike bottom. Ships are rarely reinforced in the areas most likely to be scratched or breached by grounding or striking bottom, nor is such reinforcement feasible, owing to the enormous forces that develop in such an accident. Thus, these casualties present risks from the leaking of hazardous or polluting cargoes. Damage to the ship, loss of cargo, and containment and cleanup operations can be expensive: the breaching of the tanker Tamano inbound to Portland, Maine, in 1972 cost more than $2 million in vessel damages and pollution mitigation. The designed configuration of a navigational channel, according to the National Waterways Study (1980), "influences the probability of vessel casualties." In considering strategies to enhance the safety of domestic waterways, the report states: "the only single action which by itself could reduce accidents is the structural improvement of the waterways." Depth is an important component of the designed configuration of a navigational channel. In the interest of providing the technical basis for design and maintenance of dredged navigational channels, the panel undertook an evaluation of the criteria used to determine channel depths in the United States. The panel reviewed o Criteria used in the United States for channel depths; o Considerations important to the evaluation of channel depths; o Voluntary consensus standards developed by international organizations; and o Criteria used in other maritime nations with highly developed port technology. It also assessed the adequacy of the criteria used in the United States. The results of the panel's review and appraisal are briefly summarized in succeeding chapters of this report: Chapter 2 discusses regulatory and institutional issues. Chapter 3 deals with considerations important to determining channel depth (ship movements and sedimentations. Chapter 4 addresses the adequacy of criteria for dredged depths of navigational channels and compares those of the United States and other countries, international organizations, and shippers. Chapter 5 sets out the panel's conclusions and recommendations. Abstracts compiled by the panel in a preliminary search of the literature constitute Appendix A.

1 - 6 Table 2 Gown ship types and their design data Cargo Capacity Length Beam "me (dot, unless noted) (ft.) (ft) Draf t (ft) Ferry STAMEN ISLAND 2,721 310 70 12 Tugboat JALBAR 1,010 126 36 Bulk AI.TNES Tanker MARINDUS 4,550 301 10,000 470 Shrine FRANK CA=E 23,000 643 Tender 49 60 85 21 23 25 Tanker EXXON GALVESTON 27,240 552 95 29 Dry Cargo A~ITRITI 16,952 468 69 31 Container~hip EUROLINER 40,800 798 100 32 ROMEO BOOGABm.T ~ 31,500 749 105 35 Barge Carrier YF:t IUS TUCHIK 36,382 874 115 36 Navy Tanker HUDSON 37,276 672 89 36 LNG Carrier EL PASO SOUTHERN 126,000m3 846 135 37 Ref. ined Product BALDBVTTE 244bbl 665 84 31 Tanker Tanker ESSO PORTI`AND 50,084 645 120 37 Crane Ship SARITA 42,000 677 121 37 Barge Carrier AIMERIA LYKES 38,410 876 106 39 Dry Cargo AMERICAN TRADER 29,749 820 100 41 Containership KORRIGAN 57,200 947 43 Ore/Bulk/Oil ULTRASEA 83,437 893 106 46 Bulk WORLD DULCE 133,361 570 142 52 Bulk SAMRAT ASHOK 72,600 856 58 ore SlIINRXU MARIJ 88,800 959 59 Tanker SAN DIEGO 188,500 952 166 59 Ore/Bulk/Oil RHETORIC 77,000 996 - 60 Ore/Oil BRAZILIAN WEALTH 141,800 1099 72 Bulk/Oil LAUREL W=A~1 72,300 940 72 Tanker ESSO PACIFIC 508,000 1280 233 83 a a Not acac~odated by dredged channels of the United States