CORPS OF ENGINEERS. U. S. ARMY SPILLWAY AND LOCK APPROACH JIM WOODRUFF DAM APALACHICOLA RIVER, FLORIDA MODEL INVESTIGATION TECHNICAL MEMORANDUM NO. 2-340 WATERWAYS EXPERIMENT STATION VICKSBURG, MISSISSIPPI ARMY·MRC VICKSBURG. MISS. MAY 1952 .~;;~- -~ , : ~~~~e~~~:;~ ~~ ~~;~:~i~;~~i --:=':'::':: :::==:== = :.::-_.- .__ . _ - -:-_==~~--=:;:=;.- ~ -::=..;=::--= -- .,... :.7"T::'i:T=-- I:Jb ~lII" ,. ~ . FR ONTISPIECE . J im Woodruf f Dam i PREFACE Authority to conduct hydraulic model investigations of Jim Woodruff Dam was granted by the Chief of Engineers in an indorsement dated 8 May 1946, to the District Engineer, Mobile District, CE. The studies were accomplished at the waterways Experiment Station during the period March 1948 - March 1949. During the course of the tests Messrs. George Gaines, Co E. Bentzel, R. P. Hobson, F. F. Escoffier, and G. F. Brown of the Mobile District, and Messrs. C. Po Lindner, G. H. Mittendorf, and R. W. Pierce of the South Atlantic Division, visited the Waterways Experiment Station at frequent intervals to discuss test results and to correlate these re­ sults with design work concurrently under way in the District Office. The investigations were conducted in the Hydraulics Division of the Waterways Experiment Station by Messrs. E. S. Melsheimer, C. J. Powell, and C. W. Brasfeild, under the general supervision of Messrs. F. R. Brown and T. E. Murphy. iii CONTENTS FRONTISPIECE, Jim Woodruff Dam PREFACE. i SUMl\1ARY •• v PART I: INTRODUCTION, 1 Design Features of Jim Woodruff Dam ...•••• •• 1 Need for Model Analysis .••••• 3 PART II: THE MODELS 5 Model-prototype Scale Relationships •. 5 Description •••••• 5 PART III: TESTS AND RESULTS 8 Upstream Lock Approach •••• 8 Forces on Barge TowS in Upper Lock Approach ••••••••• 15 Downstream Lock Approach •••• •• •, 16 Gated Spillway (Section Model) ••••••••'• 17 Open-crest Spillway (Section Model) • 25 Overflow Dike (Section Model) •• 28 Gated Spillway Operation 0 • • , . 29 Cofferdam Stages •• 0 32 PART IV: DISCUSSION . 34 TABLES 1-7 PLATES 1-72 v SUMMARY Model investigations of Jim Woodruff Dam were concerned with the hydraulic performance of the gated and open-crest spillways, the overflow dike, and navigation conditions in the upper and lower approaches to the locko Currents in the lock entrances and swell-head conditions at river stages overtopping the overflow dike were of particular interest. Four undistorted scale models were used in accompltshing the investigation: (a) two section models vnlich reproduced to a scale of 1:30 a 30-ft portion of the open-crest spillway and a 30-ft section of the overflow dike, respectively; (b) a section model reproducing to a scale of 1:38.4 a 96-ft portion of the gated spillway; and (c) a comprehensive model which reproduced to a scale of 1:100 the two spillways and lock and a portion of the dikeo It was determined from the model studies that certain alterations to the gated spillway and overflow dike appeared desirable in order to effect improvemepts in hydraulic performance and economies in construc- tiono The corrective features necessary to effectively and economically eliminate the hazardous cross currents existing in the upstream lock approach of original design were also determined from the model studies. The alterations necessary for over-all improvement in performance of the Jinl Woo~ruff Dam are summarized below~ a. A flat, broad-crested weir 12.5 ft wide with sloping upstream and downstream faces (type 2 design) to be used for the gated­ spillway sectiono Use of the type 2 weir also permits the end sill to 'be moved upstream 25 ft. This alteration furnished maximl@ spillway efficiency and considerable saving in con- struction costs. bo A 10-ft-radius flip bucket to be added on the downstream face vi of the overflow dike to prevent scouring attacks at the dike toe. CQ Slotted guide walls with curtain walls in the slots located at elevation 68.0 and the area between the guide walls exca­ vated to elevation 5000 (type K approach) to be used in the upstream lock approach. SPILLVlAY AND LOCK APPROACH, JIM WOODRUFFDAM APALACHICOLA RIVER , FLORI DA Model Investigation PART I : INTR ODUCTION Design Features of Jim Woodr uf f Dam* 1 . Jim Woodr uf f Dam is under construction on the Apalachicola River, appr oximat ely 1 , 000 ft downs tream from t he conf l uence of the Chat t ahoochee and Fl i nt Rivers and about 0 .5 mi l es above Chattahoochee , Fl or ida. Figure 1 is a vi ci ni ty map of the area. The dam is one uni t of a compr ehensive plan to pr o- vide a 9-f t depth f or navigation on the Chat t ahoochee River f rom its mout h to Columbus , Georgia. 2 . The proposed structure wil l consist of a dam wi t h i t s axi s about nor mal t o t he river channel, providing at extreme :G UL F l ow f l ow a 33- f t pool di f f er en- SCALE INMILES tial bet ween el evation 77 . 0 and 2 5 0 2 5 5 0 75 tO O 125 lJLX - -- 44 . 0**; and a r eservoi r ext ending Fig . 1 . Vicinit y map * Inf or mat i on on the prot otype obtained from "Def i nite Pr oj ect Repor t , Jim Vloodr uf f Dam, Apalach icola River, Fl orida . " ** Al l elevati ons are i n f ee t above mean sea l evel. 2 up the Chattahoochee River to the vicinity of Columbia, Alabama, and up the Flint River to a point about 18 river miles above Bainbridge, Georgia. The principal features of the dam from right to left bank are shown on plate 1 and consist of: (a) a conventional concrete gravity-type ogee overflow section with crest at elevation 79.0j (b) a single-lift lock 82 ft wide ·by 450 ft long with top of lock walls, guide and guard walls at elevation 82.0; (c) a gated spillway with crest at elevation 48.0, having sixteen 3005- by 40-ft split-leaf, vertical-lift gates operated by a gantry crane from a "bridge with deck at elevation 107.0; (d) a powerhouse for a 30,OOO-kw plant with intake section constituting a portion of the dam; (e) a grout-protected, riprapped, rolled-fill earth section with top at elevation 10700 adjoining the powerhouse to accommodate the high- tension switchyard and transmission substation; and (f) a grouted, riprap- protected rolled-fill overflow dike with crest at elevation 85.00 3. Alterations to the gated spillway were effected during the course of the model studies. Present plans call for the use of a flat broad-crested weir 1205 ft wide with sloping upstream and downstream faces. Details of the spillway weir as modified are SL10wn on plate 2" 4. Data pertinent to the structural and hydraulic features of the Jim Woodruff Dam, as originally designed, follow: a o structural Length of uncontrolled spillway 1584 ft Elevation of crest of uncontrolled spillway 79.0 Length of gated spillway (gross) 760 ft Length of gated spillway (net) 640 ft Elevation of crest of gated spillway 48.0 Elevation of spillway bucket (uncontrolled spillway) 69.4 Radius of spillway "bucket (uncontrolled spill~Tay) 8 ft 3 Elevation of stilling basin (gated spf.Ll.way) 15.0 Length of stilling basin (gated spillway) 38ft Size of lock 82 ft x 450 ft Lift (maximum) 33 ft Elevation top of lock walls 82.0 Elevation of lock floor 26.0 b • Hydraulic Maxim~ estimated flood 1,210,000 cfs Maximum estimated head on crest (open-crest spillway) 34.9 ft Maximum estimated head on crest (gated spillway) 65.9 ft Maximum estimated flood stage (elev) 113-9 Maximum flood of record 273,000 cfs stage for maximum flood of record 83.1 Elevation of normal upper. lock pool 77.0 Elevation of normal lower lock pool 4400 Need for Model Analysis 5. The design of the Jim Woodruff Dam structures was based on sound theoretical design practice; however, concern was expressed as to flow conditions in the upper and lower lock approaches, and currents through the span of the existing highway bridge which crosses the river channel about 0 0 4 mi below the dam 0 The difficulties and uncertainties inherent in an analytical solution of the effect of design features re- suited in model tests being accepted as the most reliable means of fore- casting the suitability of the individual designs for these elements. A comprehensive model was constructed to investigate navigation condi- tions above and below the lock, and,to provide a basis for comparison between the current patterns created by the original design and those occurring with various alternate designs. Section model.s wer e used to study details of the various structures, particularly as they affected 4 energy dissipatton and discharge coefficients. The latter information was needed 'because available data on discharge coefficients for submerged flows such as will obtain at Jim Woodruff Dam were inconclusive. Also, discharge coefficients were particularly critical for the case at hand, since it was necessary to know the swell head at which the dike at elevation 85.0 will be overtopped in order to determine the amount of protection required for its downstream face. 5 PART II: THE MODELS Model-prototype Scale Relationships 6. The accepted equations of hydraulic similitude, based on Froude ls law, were used to express the mathematical relationships between dimensions and hydraulic quantities of the model and the prototype. General relationships existing for the Jim Woodruff models are presented in the following table: Comprehensive Dimension Ratio Model Section Models Length Lr 1:100 1:30 1:38.4 L 2 Area ~ = r 1:10,000 1:900 1474.56 ~l/2 Velocity Vr = 1:10 1:5.477 1:6.197 5 2 Discharge Qr = Lr / 1:100,000 1.4929 1.9146 7.