I r JIit

l •

"'

HYDRAULICS BRANCH OFFICIAL FILE COPY

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

BUREAU OF RECLAHA.T.ION HYDRAULIC LABORATORY

OFFICE FILE COPY

WHEN BORROWED RETURN PROMPTLY

HYDRAULIC MODEL STUDIES OF TANT ANGARA DAM OUTLET WORKS MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT

SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY, AUSTRALIA

Laboratory Report No. Hyd-441

DIVISION OF ENGINEERING LABORATORIES

COMMISSIONER'S OFFICE DENVER, COLORADO

CONTENTS

Purpose of the Study • • • • • • • • • • • • • • • • • • Conclusions • • • • • • • • • • • • • • • • • • • • • • Introduction • • • • • • • • • • • • • • • • • • • • • The Investigation • • • • • • • • • • • • • • • • • • •

The Model o • • • o • • • • • • • • o • • • • • •

Gate Structure Studies • • • • • • • • •. • • • • • Regulating gate • • • • • • • • • • • • • • • • Flow pas sage • • • • • • • • • • • • • • • • •

Stilling Basin Studies • • • • • • • • • • • • • • • Preliminary operation • • • • • • • • • • • • • Basin floor elevation • • • • • • • • • • • • • • Baffle piers • • • • • • • • • • • • • • • • • Basin-tunnel transition • • • • • • • • • • • • Wave suppressor • • • • • • • • • • • • • • •

Recommended Design • • • • • • • • • • • • • • •

APPENDIX

Letter from Snowy Mountains Hydro-Electric Authority

Page

1 1 2 2 2 3 3 4 4 4 5 5 6 6 6

dated March 7, 1958 • • • • • • • • • • • • • • • .• • 1 Computations • • • • • • • • • • • • • • • • • • • • • 4 Memo to Chief, Canals Branch dated April 1, 1958 • • • • 6

LIST OF FIGURES

Figure

Preliminary Control Structure • • • • • • • • • • • • • 1 Preliminary Fixed Wheel Gate • • • • • • • • • • • • • 2 Preliminary Gate Chamber • • • • • • • • • • • • • • • 3 Recommended Fixed Wheel Gate • • • • • • • • • • • • 4 Discharge Coefficient, Recommended Gate • • • • • • • • 5 Gate Chamber Throat, Pressure Distribution • • • • • • 6 Gate Chamber Throat, Various Designs • • • • • • • • • 7 Preliminary Model with Maxim um Flow • • • • • • • • • 8 Preliminary Model, Jet Paths • • • • ·• • • • • • • • • 9 Recommended Baffle Pier, Pressure Distribution • • • • 10 Stilling Basin Development • • • • • • • • • • • • • • • 11 Recommended Control Structure, 160 1 Head • • • • • • • 12 Recommended Design, Maximum Flow. • • • • • • • • • 13 Discharge Chart, 5 to 50 Percent Gate Opening • • • • • • 14 Discharge Chart, 50 to 100 Percent Gate Opening. • • • • 15 Recommended Control Structure, 105 1 Head • • • • • • • 16

ACKNOWLEDGMENT

The author wishes to express his appreciation to

Messrs. John R. Ewers and Peter T. Brown., Engineers with

the Snowy Mountain Hydro-Electric Authority, Australia., for

their able assistance during this hydraulic mociel study.

UNITED ST ATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

Commissioner's Office- -Denver Division of Engineering Laboratories Hydraulic Laboratory Branch Hydraulic Structures and Equipment Section

Denver., Colorado Date: September 23. 1958

Laboratory Report No. Hyd-441Compiled by: D. Colgate Checked by: Wo E. Wagner Reviewed by: J. W. Ball Submitted by: H. M. Martin

Subject: Hydraulic model studies of Tantangara Dam outlet works-­Murrumbidgee-Eucumbene Diversion Project--Snowy Moun­tains Hydro-Electric Authority. Australia

PURPOSE OF THE STUDY

This model study was made for the purpose of developing an adequate Gontrol structure and stilling basin for the Murrumbidgee­Eucumbene Diversion tunnel.

CONCLUSIONS!/

1. The fixed wheel gate as shown in Figure 4 will operate satisfactorily for heads up to 160 feet. The streamlined upstream edge of the gate bottom will prevent fluctuating pressures and excessively low (cavitation) pressures on the bottom web of the gate. The baffle plates on the sides of the gate are necessary to restrict the undesirable downward flow between the outside wall of the slot and the gate.

2. The side walls in the passage or "throat., " downstream from the control gate slot., should be streamlined to prevent cavitation pres­sures in this region. An elliptical shape., with a minor to major axis ratio of 1:5 as shown in Figure 7F., will keep the wall and floor pressures in a safe range for all gate openings and discharges.

3. The stilling basin floor should continue level with the bottom of the gate water passage for a distance of 61. 58 feet from the downstreamface of the control gate., then sweep upward on a 78-foot-radius vertical curve for 29. 48 feet., then follow a reverse 78-foot-radius vertical curve for an additional 29. 48 feet to come tangent to the invert of the down­stream tunnel at Station 4+30. 96., (Figure 12).

!7 Subsequent to these model studies the plans for Tantangara Dam were modified and the maximum head on the control gate was reduced from 160 feet to 105 feet. The stilling basin discussed in this report was developed for a maximum head of 160 feet. After the modified plans ' were received., computations were made for a reduced size stilling basin to accommodate the lower head of 105 feet. Appendi~ I containsthe computations and recommendations for the modified structure.

. h ld b placed 49. 58 feet downstream

from the �on{r�f ::f!1f0P�f J�: t�; for�ation of t.he hydraulic �mih

e which will dissipate the energy of the high velo

dc1ty flow eI'iie:e �aintained

basin Flow without objectionable surges an waves, w . in the· entran�e to the 10-mile-long unlined tunnel by placing �O t_rans­verse beams and a 20-foot-long wave suppressor across the asm as

shown in Figure 12.

5 The roof of the basin should be 3 feet higher than the downstrea� tunnel roof to provide an air passage above the waves andsurges that occur in the basin upstream from the wave suppressor.

6. When the reservoir is near maximum elevation and t_he gate

is between 16 and 25 percent open, the jet sweeps t�e backwater into the basin and the control gate operates under free. d1schar�e: For <;>ther

combinations of head and gate opening, the water m the stilling :t>�sm backs up against the gate and it operates under submerge� con_d1tions. Figures 14 and 15 are discharge charts for !he gate s howing discharge versus upstream head for various gate openings; however, these c�arts are valid only for conditions as they exist in the recommended design of the control structure.

INTRODUCTION

The Murrumbidgee-Eucumbene Diversion Project is located in the Australian Alps area of southeastern Australia. The Snowy Moun­tains Hydro-Electric Authority� which is responsible for the develop­me nt of the project, has established its headquarters at Cooma near the site of construction approximately 220 miles southwest of Sydney. Tantangara Dam, about 40 miles northwest of Cooma, is a part of this project. The associated reservoir stores water from the Murrumbidgee River, and this water may be diverted as required through the outlet works and a 10-1/ 2-mile-long unlined tunnel to Lake Eucumbene .

Tantangara Reservoir feeds water into a 10-foot-diameter pressure tunnel at heads up to approximately 160 feet. The control structure, 300 feet downstream of the inlet, contains two 6- by 7-foot

· fixed wheel gates; the upstream one is used in emergencies and the downstream gate ·regulates the discharge of water from the pressure tunnel to an underground stilling basin. An unlined 10-foot 2-inch horse­shoe tunnel extends 10-1/2 miles downstream from the stilling basin, and is designed to flow free under the maximum discharge of 600 cfs .

The model studies discussed in this report were performed to determine the most economical and hydraulically acceptable design for the control structure.

THE INVESTIGATION

The Model

The model of the outlet works control structure, built to ascale of 1:10., was sufficiently large to permit accurate calibration

2

and determination of the hydraulic characteristics of the system. The ,model included the gate chamber and gates, the stilling basin, and a short section of the horseshoe tunnel downstream from the stilling basin (Figure 1). The conduit upstream from the gate chamber was not modeled.

The fixed wheel control gate model was built up of brass plates and included two non-rising operating stems (Figure 2). One side and the top and bottom of the gate chamber were welded 1 / 4-inch plate; the other side was made of 3/ 4-inch transparent plastic (Figure 3) to enable viewing of the gate leaf and flow patterns in the chamber during operation. One side and the arched roof of the stilling basin w~re of transparent plastic; the remainder of the basin was made of 3/ 4-inch plywood. The roof section was made as a unit so that it could be easily removed to allow access to the basin. ·

Water was furnished to the model through the laboratory venturi meters, with which accurate discharge measurements as low as 0. 4 cfs (125 cfs prototype) could be made. The depth of water in the outlet tunnel was controlled by means of a tailgate at the downstream end of the model.

The pressures in this report are expressed in feet of water with atmospheric pressure as a datum.

Gate Structure Studies

Regulating gate. The model fixed wheel control gate had a diaphragm-type pressure cell mounted flush with the bottom of the lower web on the gate center line. This cell together with four piezom­eters, two in the gate bottom and two in the side of the gate, were used to determine vibration tendencies and pressure distributions pertaining to the gate. For conditions of maximum design head and discharge, the control of the jet beneath the gate shifted rapidly between the upstream and downstream lips of the gate (Figure 4 D-1). The average pressure beneath the gate, as determined by piezometer readings, was approxi­mately 40 feet of water positive (prototype), but recordings made with the diaphragm-type cell disclosed the presence of rapidly fluctuating pressures which dropped down into the cavitation range.

The extended upstream gate lip was cut off flush with the bottom web of the gate (FJgure 4 D-2), leaving a sharp, right angled . corner on the upstream edge. With this design and with maximum head and discharge, the average piezometric pressure beneath the gate was about 95 feet and the magnitude of the pressure fluctuations was decreased to about 20 feet. However, the pressure fluctuations were sufficiently intense to cause considerable vibration of the gate leaf.

The -upstream edge of the gate bottom was rounded as shown in Figure 4 D-3. With this configuration, the pressure fluctuations on

,the gate bottom were about 10 fe~t. The upstream edge was then stream­lined as shown in Figure 4 D-4. With this design., the maximum pressure fluctuation was about 4 feet. This shape (Figure 4 D-4) is recommended for the bottom of the control gate.

During studies of the water passage downstream from the control gate, it was noted that a high-velocity jet flowed down the space between the side of the gate and the outside wall of the gate slot. When this flow was restricted, the pressures on the side walls downstream from the gate were somewhat improved. Consequently, a plate was attached to either side of the gate at the level of the lower web to partially block this flow and thereby improve the pressure conditions in the area of the elliptical throat. The recommended fixed-wheel con­trol gate is shown in Figure 4.

Flow passage. Under conditions of maximum design head and discharge, cavitation pressures were found to exist downstream from the slot_s of the regulating gate (Figure 6). Attempts were made to relieve the low-pressure zones by means of air vents (Figure 7B). These vents were unsatisfactory due to the fluctuation in pressures and the adverse effect the additional air had on the operation of the basin.

A plate projecting into the stream was installed at the down­stream face of the control gate slot (Figure 7C). With this flow passage the jet oscillated from side to side and increased the turbulence in the basin. An air vent was inserted in back of the restricting plate, but the conditions in the basin were not improved.

Several shapes of streamlined "throats" just downstream from the gate slots were tested. With the shape consisting of a simple curve (Figure 7D), the pressures on the .side walls were in the cavitation range, but with elliptical shapes (Figure 7E and 7F) pressure conditions were improved; the amollllt of improvement depending on the minor-major axis ratio of the ellipse (Figure 6). It was found that an elliptical shape with a minor-to-major axis ratio of 1:5 kept the pressures up to a mini­mum of negative 3 feet for maximum head and discharge conditions. This shape (Figures 6 and 7F) is recommended for prototype construction. The discharge coefficient for the recommended gate is shown in Figure 5.

Stilling basin Studies

During the initial testing of the stilling basin, the arched roof was in position over the stilling basin. However, to provide more rapid access to the floor of the stilling basin for changing baffle piers and transition sections, the roof section was replaced by vertical walls above elevation 3964. The roof was reinstalled for the tests of the recommended design.

Preliminarct operation. Tests on the preliminary design stilling basin (Figure BA an llA) indicated 'in general that the operation was

4

unsatisfactory. Large surges and waves traveled the length of the basin, filling the basin to the top of the arched roof and breaking away to form a trough 12 or more feet deep (Figure BB and C). This action was accompanied by surges of air alternately blowing out and sucking in at the downstream end of the horseshoe tunnel.

At maximum head and discharge the jet from beneath the gate followed one of two paths., In one instance the jet shot up to the surface of the stilling pool and skipped across the water surface causing ex- · tremely rough fl.ow conditions (Figure 9A). In the other instance, the jet descended to the floor near the upstream end of the basin (Figure 9B) and flowed along the floor to the downstream end of the basin and, on rising to enter the tunnel, caused a severe boil and generally rough conditions in the basin (see Figure BB and C). The direction of the jet could not be predicted but, once established, both types appeared to be stable and are examples of a flow phenomena reported by Bakhmeteff 1 /.

Basin floor elevation. With the preliminary design the probable path of tlie jet downstream from the control gate could not be predicted. This uncertainty was eliminated by raising the basin floor to the level of the floor of the-gate (Figure llB). With this configuration, the jet remained on the basin floor throughout the full range of discharge and head.

Baffle piers. In order to stabilize the formation of the hydraulic Jump, various sizes, numbers, and placement of baffle piers were tested to determine the best combination for optimum stilling basin performance. The recommended installation consists of two stream­lined piers, 3 feet high, placed 49. 58 feet downstream from the con­trol gate as shown in Figure 12. Pressures on the sides and top of the baffle piers were measured to assure that adverse pressure conditions did not exist. The results of these pressure studies are shown in Figure 10.

Three chute blocks placed 10 feet downstream from the control gate (Figure llB) tended to decrease the turbulence and the roughness* of the water surface in the hydraulic jump. However, since the velocity of the jet in this area is about 100 fps, the da.J:).ger of cavitation exists and the use of the chute blocks is not recommended.

1/ "The Flow Through Slits" by B. A .. Bakhmeteff and N. V. Feodoroff Proc. Fourth Midwestern Conference on Fluid Mechanics, 1955.

*When the basin is operating under maximum discharge and head, the Froude number is 14. 6. This is in a range where the hydraulic jump is normally quite rough.

5

Basin-tunnel transition. The surging hydraulic jump caused large surface waves which carried downstream into the horseshoe tun­nel. Added to these waves were surface undulations resulting when the water downstream from the baffle piers surged upward to enter the tun­nel. It appeared that a gradual transition from basin to tunnel would tend to decrease these latter disturbances.

Some flow improvement was obtained by sloping the basin floor downstream from the baffle piers upward to the level of the horseshoe tunnel (Figure llC). However, in each of the arrangements tested, sur­face disturbances occurred above each abrupt change of slope. The sur­face disturbances were reduced ·by using a floor transition consisting of two long-radius vertical curves. The best flow conditions resulted with a transition about 59 feet long starting 12 feet downstream from the baffle :g,i.ers as shown in Figure 11D. This transition permitted a gradual increase in velocity from the 22-foot-deep flow in the basin to the 8. 5-foot-deep flow in the horseshoe tunnel. However, large surface waves originating in the hydraulic jump continued to surge into the horseshoe tunnel portal.

. Wave suppressor. Tests of various forms of wave suppressors were undertaken to find a means of reducing the large surface waves. Flat-plate-type wave suppressors wer·e placed at various locations across the full width of the basin. No beneficial results were obtained with the suppressors placed upstream from the baffle piers. When the suppressor was placed in the path of the rising jet downstream from the baffle piers (Figure llE), the surface undulations were reduced but objectionable surface boils occured above each end of the suppressor. A series of transverse beams were placed across the channel in the area of the highest part of the jump. The beams improved surface conditions con­siderably and it was found that a 20-foot-long wave suppressor, in com­bination with the beams, produced satisfactory water surface conditions in the entrance to the horseshoe tunnel. The recommended arrangement of beams and wave suppressor is shown in Figure 12. ·

The roof of the stilling basin was raised 3 feet above the level of the roof· of the horseshoe tunnel to permit the passage of air between the large waves upstream from the wave suppressor and the roof of the basin.

Recommended Design

The recommended control structure is shown in Figure 12 and 13C. The structure will operate satisfactorily for any combination of head and discharge up to the maximum design head of 160 feet and a discharge of 600 cfs. The flow conditions existing when this system operates under maximum head and discharge are conducive to an ex­ceedingly rough hydraulic jump (Figure 13A). However, the transverse beams and the wave suppressor will assure a tranquil water surface at the entrance to the downstream tunnel (Figure 13B).

6

When the Tantangara reservoir water surface is near maximum, and the control gate is opened between 16 and 25 percent, the jet sweeps the water away from the downstream face of the gate and it operates under free discharge conditions. For other combinations of gate opening and head, water rushes upstream from the crest of the jump and sub­merges the gate. The discharge charts for the gate in the recommended design are shown in Figures 14 and 15.

7

. 0

Af .... --------------

.~2.95

t-·l..;

=ct. 'l'

2.95·1

r4-J

,••6,)811·•~•·•••••12,011 ••••-••• i

=ojj .! T ~ 0.75·~1 'r' ! -~r : J-- -- - '' ___________ t.

-~

r _J

'

i,... ...... -... ----19.0a·······-----·- i -·-·-·---------2.2.651 -------·-------~ :~

! Downstream foce of / 1' ! gate chamber flange----··

}-7t 1 I I

I :: i•+ L;,,-l2.4'ft, C

L .. _______________________________________________________________ 1j;:~;---------------------- --------- 15!...o.o~-- - --~=--------_j_, __ ----__________ -j

ELEVATION Ii. SECTION B

y ,,~====-:~=~~

j·i l""t.4 i i ' .. l::a ' .. i~ :> i .....

r I

i ! ! ! L __

-- -Left foce of stilling basin of plywood

SECTION B-B

I I I I I -. ! • 1-+i " H-t-'!.' ... -4.38~·-6.94·-~

1.31:.1 li.5a' 1.5ai1 ',1,37"

SECT ION PLAN A-A

SECTION C-C PLEXIGLAS

·-r ! I

-~ ! i

w-·-t­~-2.65-·>t

GATE OUTLINE

J N

!.'!!

MURRUMBIDGEE-EUCUMBENE DIVERSON P.ROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC_ AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS PRELIMINARY CONTROL STRUCTURE

SHOP DRAWING I: 10 SCALE MODEL

:0 ..... ~; ..,c

:u "'

•,L p'f I

~ I I I I a1 ~t, : I I

.: I I ~ I I

Lli1· nt . i : : 1· ~ I I

7 I I

41· ; I I

•.l, I : : I I

1___1: nr •J, I I ~ I I 7 I I

i ! 1~ -,-_

VIEW B-B

=;

l

·..-... : of operating stems

'•, ~-Extend this flange '•,,,_ '·,,,, to top of gate

~ ·-------- ,,--- ---- -----, f-- -, ---- i ' ' ' ' I ' I

' ' :+f-1:3:!JE=iEIS:::::::f , ' I

: 1· i : i 1· ,· 1 : ' ' ' ' ' ' : : 1

' . ' ' m '

lo ;;; ..

i I r l ,.2 piezometers ;~d;·r)

'

•' ~ ~ O>

7 ,,.-l;; • skin plate 1 ~-- on downstream J/1 face

/1 ' . ' ' 1/I ·s l .

~ N

~ 1,,.-1¾ diameter hole in : ,,: the center of web to , ,( : allow for slip-fit of•.;, -i iif·

-' : : o pressure cell ~

, ¾ • N Rs operating stem ,/ 1s' Ion~

(2 Reg d)

0 0

~ of gate-~--

o -;-- o_ 4-. --.----ri,~-----l~- i_

01 I \ . I l -.-·-··-r -I

01101- l I t' --i------i->--- --- ----- -- --- - ---- - _ _.., __

01101 , @ ' 9l2 --r------1---1 -

~r·:,mf J-,-"·~ ..... ~ " L~~t. --=~~~=~-=~=::l l ~ !*-------- 2.5 ---------- '--See detail C ~ ~ :.c .. .:. _____________________ 6.475'

j ~J-- 125° -1-<j

~l~l'-121·--t----m,·-----t-0~~ -i·----$'--t'_ -- ------ 'r--- -

-- - ---- .L.l.. - - -

'

0 "

SIDE ELEVATION DOWNSTREAM ELEVATION Gate symmetrical about C£.

\ i. 0.112) flange-+-/ /,-Drill for No.2 machine bait

,. c!//-8 skin plate

_,.,-~ of gate ~ N o·

f------------,.---,-'-·.,,':n "'"' a9 __ u_

~-,,~i----~:~···· ~--',i>--1 "'J / ,,,-Tap for No. 2 machine bolt

-----i ·' ., g

~ ~ 0 ' Ly-+---! _j_j

Jo112t-~-5:~~~-2!j DETAIL C

LOWER SEAL

! / j ·----2 piezometers in _./' · ~ ~ .,.,.

0 1 bottom web-----/ l J ~:

f============~=F==:!==~~=1:---f.J_ ms' --~--~:~:_----~~;·~'.3!~_::~ :l:;_j

1-o---

TOP VIEW Gate symmetrical about 'i..

Pressure eel I to be

~;ltt :i~. bottom

Use No. 4 bolts .J

-·---=~--T ~ : .,.--Rubber seal

_ _t_ ,{ __ ,/ i ~~::,t ·b

m o N "'

l --1 r Lo.os2 !

-=:l": ~ : Gi :

1/~------1___1.

SECTION A-A

-M~.25' i__: --,

+ ,-o-.... + ' ,,, ' 1

"! I / \ : 0 t + ;

/\~ ~I

__ /1 .,,+ ...,:.,.__~-:..-., + I J

~

'::;

,/' ·,,_ Drill bolt holes to match pressure cell

PRESSURE CELL PLATE

MURRUMBIOGEE-EUCUMBENE OIVERSON PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS PRELIMINARY FIXED· WHEEL GATE

SHOP DRAWING I: 10 SCALE MODEL

.. ~~ o,;, '=c z'° ~"' !> ~"' t

I

1h1111·~· I +

• +III I ~ +

-------,

t ttt:j'f­li I +--H---I I I I+

I I I+ I I

C II I+ fl I,+

1 ·; 'I; !i-!f c , I +

II rt~·-Lk--H N~=~;r:lt]

I I I I I 7'

ELEVATION Hidden surfaces tot

---------------·······-22.65·----··-··-------------->t

r 1r111 II' -~ ~L37' -~ J -~ f-· ------4.38~---->t<---2,95~--------6.94°!--------..;.;:~2.95'-..J,.. _____ 5.43·------ -I I I ' I I ! 1 I

., I I 0-++---- ------ ------ -----'--I

1 I I I I I I I

f-1:.i~t~~i 'ob=

~ 1.

SECTION A-A

!

L, ob

o/ _t

+7 .+ I ~

+ + + +

r·q- + L...lJ + k 'I; 1 l :1 !'•,! I i 11 + + +.J i,.; I : r------.----n I! ·1 ! I 11 I I I I

I I I I

+

+

+

r + .$ i + + l•o I ·~ 1

'l Chamfer-• I !! : I

,. -·,:_

..JLur-r __t_:_j_ I+ + + I ~ I ; r·---#=====::::::;;:=I ' + ' i -------7.20----------r~

·ii + I '6 :I ~ + ::

IZ" + - (Plexigld---J>

+ ,.--¼"steel plate ! -:----I=====::;::=

- --ft + + + + u,_1 +

+

+

+

+

+

=g !'.!

H-- 1'Plexiglos

k-----·----·- ,'---·-12.70. -·-----·---------.~--j"Steel plate,'

ELEVATION OF FLANGE-INLET Outlet flange same dimensions Do not drill outlet flange

I " t3.0··· !

----11 '.~:; -~o.75 11 r ,-1 ! !:l

1.2;;,.i ""t.;75"

-' I l + l i I ! ii

+

+ , I : 11 t- -+ 1 : • I ·l, ,r _____ i ___ lJ -

-~ r 1, -.,, ! 'l5 f- -+ I I + + +-x- -' + : ~ ! •J I } \ ! :-..ii+ + +~d- ·,+: et/ •• / : i,; \ !

.1. --+ + + + +-l. + + \ + ! ' l : \; _i

.,.;Lo•k..:,eq,sp.of 1 ... -·~-2eg.sp.of2.2Z-.!c---Jeq.sp.ofLB~----/~..__GJand section from

/ 111nonrlslng stem gate

PL A N : ~~~: ~4~:1:.=1.~ ! 11ft shaft, each side . i

!

')"Steel plate II r ~ ! ~ l .. !

1 steel plate j j

I _i ! li--,~--~-, .. ·-~ -rt.--2.4,....:

ELEVATION COVER PLATE

SECTION B-8 SECTION C-C

MURRUMBIDGEE-EUCUMBENE DIVERSON PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUT.LET WORKS PRELIMINARY GATE CHAMBER

SHOP DRAWING I: 10 SCALE MODEL

~ ., C:

z"' P"' !"'

FIGURE 4 REPORT H0YO, 441

·c,_-.

Bcffle plate, r··_---------- 2'-s" ____ . __ ,_, -------------------------- s'-o" ------------------------- -~-•-.

~--\r:-1/:: ___ ~: _____ :~2s;·~-~~ ® l>-- ~-'-' .• -'-'-"'-...;..........:....'-'--'--'--'------,

Baffle plate-,

610

' ' =-1.., "' - ' N

' '

-:· .. ·. -· . ·.: .. :--,.

L>­c

L ; r.L· ,........,._...£SL~~¢:----------------:rl:---::,-~L.~~-----l · ,;. -----------------------?~ .J~ ~-"<i·.'. -~ .. :- .. ·-:: :: .. ·-~>:-: •· I . I . ·_.,':'::

I I

P L AN A-A

Lower beam, upstream face----

.,,_~ ... -Flange

- 1.095

' '

... N

'f' '

_____ L

D-1

: /

Web

,-Web

! I \ 1 k--1 6 11- ........ ~ ---~

: . ' D-2

n _,,web

, .......... ~ !

D-3

I - • ~.'!<;,,C)

I/ : W b • - : .,/ e ' :

1.293"- ____ ..

2. 500• ...... --------

D-4 Recommended

SECTION C-C BETWEEN@ AND®

1r Skin plate-------------,

~

---------...... / '

( 0 ' ' /

' ----/

,,,.----- ........ / '

( 0 Baffle plate at ' '

,/ ..... ___ .,.,..

I -~

R, I I

~

~

I

~ I

I ___ '(_

T '

I -A !7 ' I I I

this location-----.,.____ v ~ : fl ....

"' R = N <i> :

'f- II -.Li 0.751~:Jk-------·21.461~----J k--- 3.50

ELEVATION B-B

6 1 x 7' FIXED WHEEL GATE

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS

DEVELOPMENT OF RECOMMENDED GATE SHAPE 1:10 SCALE MODEL

110

i >,1----,---1 g .. CP .. .. E ....

.l!! 0 CP

~ ·-~--8 -f ®

ELEVATION

x2 y2 ->t 2..s'~·-5.83!--->1 2..511+/~ + o.so8• =I

Baffle Plate-. --

i.as-!'-J

Fixed-Wheel Contro I Gate

L,.. A

FIGURE 5 REPORT HYD. 441

HALF PLAN c-c

., N l'-uj ....

,---i 'r' ' I j_~

i.c-------19_31!'--------..l 4.85'1..-

S EC TIO N B-B H-=; H \ {,-Origin

----... +.......J. . ' I lL.J ... _!l-"_i ... -------0-.8....,81,....... ___ _

: -+

---6 (\I

f ->t 3.501 ~ f * u.----Lr"·;j_

P L A N

~ • 1.895~ -1 ( --., ' ~ >·!-------,

,7: Pt, -,,, -----~A_Q:.L i I

l.29311R-- • ..,.,...,/;• .8 : •a, j 11 : Iii

/ Ii> I "' o<·------2.0.41-------- ... 4.85 ,.... I C\J I ~

I

A CHAMBER SECTION A-A

8 GATE

RECOMMENDED INSTALLATION

0 .85 I I I

0 Q ·- Cd=

A v'2.g (Ho- H1)

0 .B A = 6 x Gate opening in feet

0

0

0

.8 \

\ .Bl

\ .8

' J' 0 .7

0 .78 \ ,.,,

o. 77

0 .-o. 75

74 0.

73 o. 0 10

\

" ' ,/ r-..... r----. ~ ---·-· I

' 20 30 40 50 60 70 80

GATE OPENING-PERCENT OF HOOT TRAVEL

C DISCHARGE COEFFICIENT

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS DISCHARGE COEFFICIENT

RECOMMENDED DESIGN

/ /

90 100

610

FIGURE 6 REPORT HYO. 441

.•• •• •. • •.•.I o ,: .': : : • ·: ~ ... ···:.--• . ·. :• ::· ... . :• =::: ::: ... ..

:·: .!: :-. ; ~ ; ::: -:·:: :-:~ -:~:: ... : .: . -: .:.:_ ..

30" X 30" GATE SLOT

FLOW :>-

7.01 gate opened 20 %.

Velocity 5ft. os from gate is 97 ft. per. sec.

Pressures shown are o.oa' above the floor.

Approach passage Is 6' wide

. .. ·:.

... ::--=< -----------61" ---------~ ;., I

:=:-:- ·· :· -:· :',: :·:·:: :_.-_. :•i: :. : :·: '-:·.-·· = ·:: ·: ·: :·:·: d-=::-: ,'1 \,J,~~ 1. 5" R : : --~----- ---- _ _J \ '-P.T. ' ' -square corner

. -----------61" ---- --- >I :;·------40"------.>l I )-;'.·;:;•;:: ;,,,;;,.·.:·::·· .. :·.·=-'I.-...·,:·.=:: :•::.I:.'.'.:

',---t:'._:4 Ellipse : '~Origin of 1Ellipse

-----~---~-_J tP.r. '-Tangent extension

40

30

a::: I.LI

20 .... C(

~

IL 0

.... 10

I.LI I.LI IL I

Q C( 0 I.LI ::c

I.LI a::: ::::, (/) (/) -10 I.LI a::: a.

-20

-30

0

:<-- ----- 54.5"-- ---->I i:.-----42"------>l I :·.:: ·. ··.· ... : .·· .... •. :.-.: .. -:::.1· :J. .....

\_ -~llipse ! 1-,origin of ~, ___ __J

~ ,:

\

\\ 1, I,\

\ I

I

i I

ti I I

\ J I

\~ _rt.

\\ \ \ ,/ V \

~ 1/j' .• -1!5 Ellipse (recommended) I --· ---I ---"*"" I ---/J 'tx- .L -·- ~--~ 1: 4 Ellipse with - K_... ,1 ........... ' tangent extension .... .,

~I j .... i..e-- ----- --, .... -.::! ,, .,,

_r,, .... .... -.J _ ... --i:4 Ellipse

I

I I f- -I-Square corner

r I ---- <-7.5" Radius ,- Cavitation pressure

I

~

10 20 30 40 50 INCH ES DOWNSTREAM FROM GATE SLOT

MURRUMBIDGEE- EUCUMBENE DIVERSON PROJECT SNOWY MOUNTAINS HYDRO·EL.ECTRIC AUTHORITY; AUSTRAL.IA

TANTANGARA DAM OUTLET WORKS PRESSURE DISTRIBUTION IN GATE CHAMBER· THROAT

VARIOUS DESIGNS 1:10 S A L

60

Elli pse

70

610

r------3of------1 ---Control gote

/_/- slot

·-------------6(' ---------------...: -~ ! •

Flow

A PRELIMINARY

,..4"Air vent / 3 inches above floor

B AIR VENT

.,L .. 1-=-----------' ·co Q "A· t ··r·· .. _-4 1r ven ' ·---.Projection

C PROJECTION INTO THE STREAM

With and without air vent

D

FIGURE 7 ... REPORT HYO. 441

.• ---··7. 5"Rodius : I r-1- It) ...,

' :-----... ~-------------- 61 11 -------------.>i !

7.5• RADIUS STREAMLINED THROAT

xz yz ,/(40)2 + lio)t=I

'/ ,..Origin

'( I I •

I ----J I 2 i 11 :···---.~---~;-r·-·, ,..,. ____ · -40 --- --·------ 21 ----~

Extension/

E 1:4 ELLIPSE STREAMLINED THROAT

With and wilhout extension

~ + _r:_ = I '',/ (54.5)2 (I0.9)2

:-Origin

I { ........ ---<,>------0 ___ __, =~ :

,---K--: ! I I ! ~---------42!~-------->K-1,;-,,.J ,12.5 11

, .. _ .. ,

F 1:5 ELLIPSE STREAMLINED THROAT

Recommended

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS DEVELOPMENT OF RECOMMENDED GATE­

CHAM BER FLOW PASSAGE 1:10 SCALE MOOEL

A. Preliminary Model.

B. From Sta. 3+25 to Sta. 4+20 G. 0. ·= 24o/a; Q = 600 cfl:f.

C. From Sta. 3+90 to Sta. 4+90 G. 0. = 24%; Q = 600 cfs .

Figure 8 -Hyd. 441

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS Preliminary design; note rough water surface

1 :10 scale model

A. Jet shooting up to the surface.

B. Jet flowing along the floor.

Figure 9 Hyd. 441

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS Preliminary design showing both level and rising jet

1:10 scale model

FIGURE 10 REPORT HYO. 441

--.-l 6" ~­I i --r--,-

• J ,1' I I I ~3"R I I _,

0 0 I()

I I

: o~F OG I C D

OH

,5.2811

1 I,, -->I 9" j<J~

I I I I I I 'P. T

-J--l-----' "1 . . -1() I 'o 23 11 -=1- -- ------1 . C\I OK

J a, in <'!

--t--1 I I I -.,.

C\I I I I

~,1s"----;Ht-----J _ _j __ _ I I \ __ J ___ ..,A_.e ________ ~ -<---------.---\ x2 y2 *

I I r--------3.50 I :-,-, ~, ,STA.3 + 60.0

PEIZOMETER

HEIGHT ABOVE FLOOR

I I

---------~ I

A B

.2 .2

C D

.3 .4

E

.5

(1.1896)2 +(.2691)2= I : -a,

F G H

.6 .6 .6

J

2.75

C\I co d

K

2.75 ( FEET ) PROTO.

DIST. DOWNSTREAM

PIER FACE

0 0 .02 .I .2 .35 .7 1.75 0 .75 ( FEET ) PROTO.

~ 25 >-1-

~

OA

0 20 a:: a a. I-I.LI ~ 15

I.LI a:: :::> 10 Cl) Cl)

I.LI a:: a. 5

610

D

W.S. 19. 7 FEET ABOVE FLOOR

Q = 600 C.F.S.

GO= 20.3%

H

MURRUMBIDGEE- EUCUMBENE DIVERSON PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARA DAM OUTLET WORKS PRESSURE DISTRIBUTION

RECOMMENDED BAFFLE PIER I: 10 SCALE MODEL

610

FIGURE II REPORT HYO. 441

,,-El. 3969, 32

7 __ El. 394 7. 57 l:',EI. 3943.57

.,.,,.,.T o 10L2" Dia. Horseshoe

tunnel

I : Lsta. 3t 15.5 Sta.4t65.5J

A. PRELIMINARY DESIGN

,,r3 chute blocks /2 baffle piers

rEI. 394 7. 57

L __ .J.-___________ l \c::-3 baffle piers ______________________ _J I : \.. Sta. 3t 25 \.. Sta. 3+ 63

_)

_)

8. ADDITION OF BAFFLE PIERS AND CHUTE BLOCKS

"', I ' --- ------

- Ste. 3+56j : Lsta. 3 +87

Lsta. 3+63

---

C. ADDITION OF SLOPING FLOOR

P.C.

' Sta. 3t 50J -..Sta. 3 +72

,-El. 3972.62 ....£........ ,,-El.3469.32

: ~ ~--IOL>j

P.T.

! Lsta. 4 + 40. 96 I

Lsta.4+30.96

0. ADDITION OF CURVED FLOOR AND SHORTER, WIDER BAFFLE PIERS ROOF RAISED 3 FEET

Sta. 3 tao: r Sta. 4+00 i::::::===::::i: _El.3964.30

E. REMOVAL OF CHUTE BLOCKS AND ADDITION OF SIMPLE WAVE SUPPRESSOR

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY;AUSTRALIA

TANTANGARA DAM OUTLET WORKS STILLING BASIN DEVELOPMENT

I: 10 SCALE MODEL

., 0

Gate Slat····'!'

A B C D

7 r . ____ r>- r>- . . Deta1 I E -. ,.,._ 10- ---<>i ,

~------------------------.:;:>a=:,,..,...-------l--' ~-- ------~-Y-

Shelf El. 3967.22 · ••

r~r : <O

121000000 ~--Sta. 3 + 78.00

I .!..I CS>.

'···P.T.

' -..., !

-$ ~:~---,~~:::~~-t. El. 3947.57···

~ ' ' )

. El. 3959.14 ~ Sta. 4+ 30.96

D "' CS>.

~

-.-1 A

Gate

4>-B

~~c. ~.394757 s~. 3+1~00

ELEVATION

···P.R.C. El. 3953.36 Sta. 4 + 01.48

' ' I Ill

>i6 ~

' ,' : ,:3uR I : ~I

,,,.~."T"": ~ 111111111111111111111 If?[ : I : I i I I I I ' l I, I :

T·~',_:, ·o

0

'?

.:L I ' ' :-""-----3.50 - ------~

ELEVATION ~--10.0---~ -- ------- -- - --- - 34.50--- --- -- --- ~--- - --18.0-- -- - --~-- ------ - -:1 ---3,~ .00 -- - ----- - ~--- -- - 20.00 ------>,2.96r*- -10.0-->:

Sta. 3+ 15.50---~ 10-16 x 16 Baffles Wave suppresser : Transition ~- - ----- - -- - · -- ------·- - - - - - - --- - --- - - --- - ---- - ----- --- -- · 115 46--- - - - - · --- - -- - -- --- -- - - - --- - -- - -- -- - -- ---- - -- - - ---~

El. 3947.57

' PL AN '

-~-- -=r~ =<O 8' - .s'J_,.

Y. I :C\J I

I

El. 3972.30

-ill "!

'"' 7·f ·~, : =~ ';'

--- _J_j

·c,, ~~-- --f-r·

'·Roof of Stilling Basin \

~-161~>1 I

:. ___ :_y_ I

PLAN

Pl E RS

"' <O 0

Shelf, EL 3967.22···

A-A B-B

s·~ -~ :!.Sta. ,

~~22 , , ,, , ~ 4+08.00 '

<'"-i:J ~/ ------------- --

DETAIL E

MURRUMBIDGEE- EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY;AUSTRALIA

TANTANGARA DAM OUTLET WORKS RECOMMENDED STILLING BASIN FOR 160' HEAD

1; 10 SCALE MODEL

"'11

C, C :u ITI

N

A. From the Gate to Sta. 4+05 (Gate seal is Sta. 3+10.42)

·. G.O. = 190/o; Q = 600 cfs.

B. From Sta. 3+90 to Sta. 4+85 G.O. = 190/o; Q = 600 cfs.

C • . Recommended Design.

MURRUMBIDGEE-EUCUMBENE DIVERSION PROJECT SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY; AUSTRALIA

TANTANGARADAM OUTLET WORKS Recommended design

1:10 scale model-

~~ 'C~ 0 '1 ::l.m Ill .... ~c., ll-. ~ ill>, ....

160

150

146

I

I

I 130

120 a:: w ~ 110 ;:: la. o 100 1-w w 1a. 90 iJ' I-

~ 80 w J:

t- 70 ~ ~ 60 w J:

...J 50 ~ 0 I- 40

30

20 I

I 10

0

I ,

/ /

J J / I I I /

GATE OPENING- PERCENT 5 / I

I / V i / 10

I I /

' /

I / 15 V

I / /

I V ..,v / V' 20/

I I ~v i/"' / /

/ I / ~/ ,

_25/ / I ,,

I I ~/ V V /

V"

/ / ~

I I V V' V / 30 _........

,/ ~ / ,_,.. J ..............

I V V ..v V / 35- ....--/ / / ~ ............... ~_........ l..--- l.---"" 40"

I / /' V v- ~ ..- ............... ~ ~ -/ / ~ ............... .............. l.---"" .-- -45----- ---- i--- so-

I / V V ............... - .............. - ----~ ~ ~ --/ ~ ............... ~ l-----~ -- i-----/ l..,......-"' .-. --- -- --- --/ V / V'" ~ -- c::::; t:::::=== ::::::-: -:::::: c::--- ~ - 500 525 550 575 600 625 65

/ V L....--"" _.... ~ t:::::::= ~ /' ~ ~ MURRUMBIDGEE- EUCUMBENE DIVERSION PROJECT

/ SNOWY MOUNTAIN HYDRO•ELECTRIC AUTHORITY, AUSTRALIA

TANTANGARA DAM OUTLET WORKS DISCHARGE CHART

25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 DISCHARGE, CUBIC FEET PER SECOND

0

.,, i5 C :u

"' i

42

I 40

38 I

36 i

34 0:: ILi

~ 32 3:: IL. o 30 1-1,J ILi 11.. 28 w· I-

~ 26 ILi :I:

1- 24 ~ ~ 22 ILi :I:

-I 20 ~ 0 I-

18

16

14

12 ~~ -

.........-::: ~ ~

~ -~

....-!:: ~ ~ ~

GATE OPENING PERCENT 5/

// / V / / / V /

V ~ V /

~ V / / J

V / V ::::=:: ~ / .-, :::::: ------~ ~ % ::::-:::: ::::---:::: ~ % %

/ :::::.--::::: ::::::::; ~ ~ _.

~ ~ ~ ~ ~ ~ -~

~ -=

/ -~

,/ V ~v

/ / / / /

V V /

/ / I/ J

V

V ,

V / / / /

V / / V / ,,, / I/ ~

i..-55 ;I' V / .,,, /

,..so 65/ / V ~ J ./

V V 70 v / l/ I/ / 75/ / ~ 80 .-

r:::-~ /..- 85- t::--:: 1/ .__.,,,,,. ~ 90 -:::::: ~

~ t::::=":: ---~~100 ::::::::::~ =--=--= c:::-----

500 525 550 575 600 625 65

MURRUMBIDGEE- EUCUMBENE DIVERSION PROJECT

SNOWY MOUNTAIN HYDRO-ELECTRIC AUTHORITY, AUSTRALIA

TANTANGARA DAM OUTLET WORKS DISCHARGE CHART

100 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475

DISCHARGE,CUBIC FEET PER SECOND

0

~il 13~ a~ , ..... ,~

Cl 11 0 .. I

. ;;

;

A C D r>- r>- ·o :~··j Detail E····::Y==>; . l"""' ........... 1-J. {~) : -J. ... . p O O O D ~-.c~_S/Wave supp~esser 1 r-2.96'

l -i , 1 : I ~------ 20.00------>-: j

7 B r>-

i .,; :'·······16······~·· 8 Beams -26.00······>-1 -:_ __ ;,.i. ~, ~===+, == t i : 8 1 11 I :

~----~;~-~-.~:~---! ~ . --; -----------t.----------Y- 0-~~~-o---~ ': I --P.C. j ~ ~ :

~. ··· · · · ·· ·············· 46.08' ······· ······ ········>f"· ·· 12.o'···>f<·· ••···• ····26.48' -········-·J,. .. !. ...... 26.48'·············~

~ ;>- .ELEVATION ~ ~>-

NOTES A model study (1: 10 scale) was made to deter·

mine the stilling basin design for o discharge of 600 cfs. and a head of 160 feet at the gate.

Subsequent to the model study plans were modified to require a discharge of 600 cfs. and a head of 10s feet at the gate.

The dimensions shown on this drawing result­ed from a compu ta lion for the new require­ments based on the results of the model study.

' ' ' ·.;, <D "'

' . . fi ' I I 17° "d ~ 1 1 1 6, <'Basin varies rom 6.43 o o. w1 e >··········-··-···············-· 10.0·->s

~1:~·:---:------------ -------------- .... -~,·~ ..... jj I fr I Ii if I 1' 11-111 I ':>t: ·-0.88

.'I'. ' ' :...-----------42 o'~-----------~ ' SIDE ELEVATION '

r ' -0

O> ,-:

T : I I

' I I I I I

:L

' ,'3' +

•'!-'

iA-A

c-c

ie-B

PLAN

D-D TRANSITION

---------- - Stilling Basin Roof ',

-~ \ Shelf···

Wave suppresser····

I ' '

··Stilling Basin Wall T =~

~ CO I II re:--------- 33.o• --------~ . : ,..; i"49.0 ->j ,··PT , ___ j_

_y __ t--- . . + : _p··Origin : :r· T •_:,

~ -__ x_•_ .. __ v_•_ II I ~ ' (i4.2752)2 (3.2292)2 ':'

(Inches) i ____________ J ___ i "o ~

----i.--- ·4 PLAN

BAFFLE PIERS

~ T pll///J/F/L1 . '., .. ·:::: j' ---24-->i 18 '"*·24·->i •

1 I I I

·--, ~ . ~I - ... ,. ..... ,._'"'""""' ............ ,= "--...___ Beams / 0 SNOWY MOUNTAINS HYDRO-ELECTRIC AUTHORITY;AUSTRAUA

_____ _......,,, TANTANGARA DAM OUTLET WORKS

DETAIL E RECOMMENDED STILLING BASIN FOR 105'HEAD

"Tl

Ci)

C ::u Ill

OI

APPENDIX l

COPYCJW

UNITED ST ATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

Snowy Mountains Hydro -Electric Authority P. 0. Box 332, Cooma North, New South Wales, Australia

Airmail: March 7, 1958

To: Assistant Commissioner and Chief Engineer Attention D-220

From: Senior Engineering Advisor

Subject: Murrumbidgee-Eucumbene Tunnel Designs--Murrumbidgee­Eucumbene Diversion

Design of the Murrumbidgee-Eucumbene Tunnel including intake, control and outlet works was carried out by the Bureau on the basis of information and requirements outlined in the Authority's In­terim Project Report of January 1957. The designs prepared by the Bureau comply with all requirements_ given therein and include an energy dissipator immediately downstream of the control gate.

Subsequently, plans were modified to include construction of a concrete gravity dam at Tantangara with full supply level at RL 4035, which is 72 feet less than the reservoir level adopted for the design of the tunnel and associated works. In view of this change in operating lie ad savings may be effected by moving the gate shaft up­stream, thereby reducing the depth of the shaft and dimensions of the energy dissipator immediately downstream of the gate.

Some regulating conditions, as recently summarized by the Engineer-in-Charge Civil Engineering Design, follow:

"Consideration has been given to ihe desired degree of regulation of flow through the tunnel. No difficulties are foreseen in regard to operation of the tunnel in the free-flow or in the full­flow condition, but it seems undesirable that the tunnel be operated in a condition intermediate between full-flow and free-flow as any transient pressure waves could cause damage in the unlined tunnel.

Three alternate methods of gate operation have been con­sidered and these methods are compared below:

METHOD A

. Flow regulated so that the tunnel flows part-full at all times. In this method the gate is required to regulate for 20o/o of the time as for the remainder of the time the river flow is

less than the free-flow capa~ity of the tunnel (500 cusecs). How­ever, the maximum discharge capacity is less than that for full flow operation (6 20 cusecs).

METHODB

Flow regulated so that tunnel flows either part full or full for its entire length and operation in the intermediate condition is avoided as far as practicable. This method would involve opera­tion in accordance with Method A up to RL 3992., which is the level

- in Tantangara Reservoir above which it is possible to fully open the gate and achieve full-flow throughout the tunnel. This would permit the discharge capacity of the tunnel to be increased to 620 cusecs for the higher levels in the reservoir. The main disadvantage of this method is the operation in the transition stage for short periods when the reservoir water level passes through RL 3992.

METHOD C

Flow regulated so that tunnel operation is intermittently full flow or zero. This method would require that the gate operated intermittently for a large proportion of the time., which means that the flow would pass through the transition stage each time the gate is opened. In order to ensure that the tunnel flowed full at all times it would be necessary to raise the minimum operating level from RL 3960 to approximately RL 3992.

It is proposed in the Investigations Report that remote con_. trol be provided for the regulating gate together with remote indication of the gate position. It is also proposed that remote indication of water level be provided. Thus., it will be possible to have the remote control of gate opening depend on reservoir wat~r level and the selection of the amount of gate opening can be either maqual or automatic. It is con­sidered that the control of gate opening would be a more routine and less complicated procedure if the tunnel were operated part-full at all times. As the difference in the maximum discharge capacity (part-full and full) is only approximately 120 cusecs it is considered that opera­tion in the part-full condition will not cause any significant loss in water diversion.

Operation of the tunnel part-full at all times is preferred (Method A). This method avoids operation in the transition stage be­tween full and part-full and control of gate opening would be fairly straightforward. "

A sketch DT-H-9 "Murrumbidgee Portal - Murrumbidgee­Eucumbene Tunnel - Alternative Arrangement" (two prints enclosed) has been prepared which., together with the above notes., summarizes present requirements., and it is asked that designs proceed along the suggested lines and within the broad limits of the proposed change in­dicated in Section B (17) of Supplementary Notice No. 1 to Contract No. 20., 034.

It is regretted that finalization of Authority thoughts on this feature of the Project has been delayed. Several alternatives, which involved relatively major changes, have been under consideration and were only eliminated definitely as of this date.

In duplicate Enclosure

3

s/ Fred E Cornwell t/ Fred E. Cornwell

Senior Engineering Advisor

As a result of the change in plans mentioned in the foregoing letter from SMHEA, the maximum head on the control gate was reduced from 160 to 105 feet, permitting a reduction in the size of the stilling basin. The new basin dimensions were computed as follows, without additional model studies: -

1. Values existing in the basin as determined by model studies and recommended for the initial plan:

H = 160 feet; Q = 600 cfs

V 1 = 99 fps

D1 = 1. 42 feet

D2 = 22. 5 feet

L = 7 4 feet (end of hydraulic jump)

,99 F = I. 42 g = 14. 6

2. Computed from Laboratory Report No. Hyd-399 (Laboratory Research Study on Stilling Basins):

a. For the initial plan:

n1 = 1. 42 feet

F = 14. 6

D2 = 20 D1 = 28. 4 feet (Hyd-399)

L = 2. 8 D2 = 79. 5 feet (Hyd-399)

b. For the modified plans:

H = 105 feet; Q = 600 cfs

D1 = 1. 72 feet

V 1 = 82 fps

82 F=1. 72 g=ll.0

D2 = 15. 2 D1 = 26. 2 feet (Hyd-399)

L = 2. 8 D2 = 73. 4 feet (Hyd-399)

3. Computations based on the ratio of the dimensions for the initial and modified plans as determined from Hyd-399 and applied to the initial model study results-:

4

Hyd-399 Initial Modified Initial Modified Ratio test (Test X Ratio)

D2 28.4 26.2 0.923 22. 5 20.75

L 79. 5 73.4 • 923 74.0 68.25

4. These computations indicated that the basin dimensions de­termined by model study for the initial plans could be modified and new dimensions recommended for the modified plans without the need for further model studies. Consequently, the following memorandum was prepared for the Bureau design branch concerned with this control struc­ture. ·

The drawing, Figure 16, shows the recommended stilling basin for the revised maximum head of 105 feet. Since the relative elevations of the gate and the horseshoe tunnel downstream from the stilling basin have been reduced 1. 75 foot, the discharge charts, Figures 14 and 15, may be used for modified stilling basin as shown in Figure 16 by reduc­ing the total head values by 1. 75 fedf.

fee+

5

COPYCJW

Memorandum To: Chief, Canals Branch

Attention: W. W. Schneider

From: Chief, Division of Engineering Laboratories

Denver, Colorado April 1, 1958

Subject: Murrumbidgee-Eucumbene tunnel intake control structure

Model studies have been completed for the design of a stilling basin to dissipatethe energy of 600 cfs entering the pool with a velocity of 99 feet per second. The plans at the time of the model study assumed a reservoir water surface elevation of 4107 and a stilling basin floor elevation of 3947. 6, or a head of about 160 feet on the gate. Recent modification of the plans by SMHEA indicate that the maximum reservoir elevation will now be 405.2 which reduces the head at the gate to about 105 feet. The discharge will remain at 600 cfs. The authority by letter dated March 7, 1958, asked for revised dimensions for the energy dis­sipator using the lower design head.

The stilling basin determined by model study was somewhat shorter and shallower than the minimum values computed using the data from Hydraulic Laboratory Report No. Hyd-399. The water sur-face in the jump was extremely rough; hqwever, by placing 10 beams and a 20-foot-long wave suppressor across the basin, tranquil flow was maintained in the entrance to the 10-mile-long unlined tunnel which leads to Adaminaby Reservoir. To arrive at an acceptable design for the new basin, computations were made (using the Hyd-399 design curves) for the initial head conditions and for the lower head of the modified plan. The ratio of these values was applied to the basin dimensions developed by model study to determine the minimum dimensions for the new basin. These dimens~ons are shown on the accompanying drawing.

The basin design for the initial plans was the most economical which could be developed by model .study, and the computed dimensions of the modified basin are considered a minimum for proper operation of the stilling basin. It is believed that the new basin under the smaller head will operate as satisfactorily as that developed for the higher head, and that further model studies are unnecessary.

The information contained in this memorandum will be included in the Hydraulic Laboratory report covering the studies made on the con­trol structure. The report will be completed in the near future.

s/W. H. Price

6