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ALASKA POWER AUTHO~ITY
SUSITNA HYDkOELECTRIC PROJECT
DESIGN TRANSMITTAL
SUBTASKS 6.02~ 6.03J 6.06 -PRELIMINARY
DESIGN CONSIDERATIONS
FEBRUARY 1981
ACRES AMERICAN INCORPORATED
1000 Liberty Bank Bui1ding
· Main at Court
Buffalo, New York 14202
Telephone (716) 853-7525
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A1aska Power Authority
Susitna Hydroelectric Project
Task 6 -Design Development
Subtasks -6.02, 6.03, 6.06 -Design Transmittal
Preliminary Design Considerations
Associated with Projec~ Definition Studies
TABLE OF CONTENTS
Pa~
1 -INTRODUCTION --------~------------------------------------------1
2 -APPROACH TO PROJECT DEFINITION STUDIES ------:------------------1
3 -ELECTRICAL SYSTEM CONSIDERATtnNs -------------------------------l
4 -GEOTECHNICAL CON~IDERATIONS ------------------------------------2
4.1 -Main and Sz.ddle Dams -------------------------------------2
4.2 -Temporary Cofferdams ------------:,------------""------------2
5 -HYDROLOGIC AND HYDRAULIC CONSIDERATIONS ------------------------2
5.1 -General --------------------------------------------------2
5.2 -Sizing of Hydraulic Components ---------------------------3
6 -ENGINEERING LAYOUT CONSIDERATIONS ------------------------------3
7 -MECHANICAL CONSIDERATIONS -~------------~-----------------------3
7.1 -Powerhouse ----------------------~------------------------3
7.2 -Overflow Spillway -------------------------------~--------4
7.3-Miscellaneous Mechanical Equipment-----------------------4
8 -ELECTRICAL CONSIDERATIONS --------------------------------------4
8.1 -Powerhouse -----------------------------------------------4
8.2 -Switchyard and Transmission lines ------------------------4
9 -ENVIRONMENTAL CONSIDERATIONS ----------------~------------------4
9.1 -Flow Constraints -----------------------------------------4
9.2 -Water Level Fiuctuation Constraints ----------------------4
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1 -INTRODUCTION
The objective of documenting the following design considerations is to
facilitate a standardized approach to the engineering layout work being done
as part of Subtasks 6.02 11 lnvestigate Tunnel A1ternative 11
, 6.03 11 Evaiuate
Alternative Susitna Developments" and 6.06 11 Staged Deve1opment 11
• The
mate.ri a 1-presented is very· pre 1 imi nary and deta i 1 ed enough on1 y for the
project definition studies. The numbers presented are very often based on
judgement and should not be confused with the more ciefinitive ''design
criteria 11 which will be produced next year
Throughout the execution of Subtasks 6.02, 6.03 and 6.06 the design
considerations were modified and several draft copies of this document were
issued for internal use. This final documG~t outlines the final version of·
the design considerationsq
2 -APPROACH TO PROJECT DEFINITION STUDIES
The general approach to the ~reject definition studies ifivolves three
steps:
(i) Single Site Developments:
All sites are treated as single projects.
(ii) Mu1tisite Developments:
Two or three sites are developed in a series. This means that
the downstream sites may have installed capacities, spillway ~nd
diversion czpaciti~s, and drawdown levels which differ consider-
ably .rom the single site development.
(iii) Staged DeveloQments:
Development at a site may be staged, i.e. the dam crest level ~~y
be i ncr·eased and the powerhouse capacity expa'nded.
Although the steps follow consecutively, there is considerable overlap~
and work could be progressing on all three steps at the same time.
This document essentially addresses the step (i) type studies. Careful
interpretation of the information is required when applying it to stage (ii)
and (iii} studies. If modifications are requ·ired to the basic data presented
here the appropriate departmental c~ordinator should be contacted.
3 -ELECTRICAL SYSTEM CCii!;JDERATIONS
The current total system load factor is reported to be of the order to 50%
to 55%. The 'IJCC proj8ctions indicate that this may go up between 56 and 63%
in future years.
Initially, all projects should be sized for a 45 to 55% capacity factor and
should incorporate daily peaking to satisfy this requirement. As a later
step, some of the proposed developments could be reanalized for higher or
lower capacity factors.
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All projects should be capable of meeting a seasonally varying power demand.
Tab 1 e 1 \vas deve 1 oped from data contained in the l~CC Subta:s k l. 02 report
and 1 ists the monthly variation in power and energy demand t ·:.t should be
used.
The installed capacity and reservoir level regulating rules should be
established so that the firm energy output of the project is maximized.
Ltsted below are the power/energy definitions to be nsed for this study.
The list is limited to terms used in the project definition studies. The
definitions are preliminary and may be modified during the subsequent steps
of the feasibility studies.
Average Monthly or Annual Energy -The average monthly annual energy
produced by a hydro project ov~r a 30 year period of operation.
Firm ~~onthly or Annual Energy -The/minimum amount of monthly or annual
energy that can be guaranteed eve~ during low flow periods. For purposes
of this preliminary study this should correspond to the energy produce~
during the second lowest energy producing year on record. This corre:~,Jnds
roughly to an annual level of assurance of.95%.
§econda~i Energy-Electiic energy having limited availability. In good
water years a hydro plant can generate energy in excess of its firm energy
cap~1ility. This excess energy is classified as secondary energy because
it is not available every year, and varies in magnitude in those years when
it is available.
Installed Capacitx -The rating of generators at design head and best gate
available for production of saleable power.
a
4 -GEOTECHNICAL CONSIDERATIONS
4.1 -Main arid Saddle Dams
The geotechnical considerations o:·e summarized in Table 2.
4.2 -Temporary Cofferdams
It will be assumed that all cofferdams are of a fill-type. Since much of
the ori"inal river bed material under the main dam shell may have to be
excavated, all cofferdams should be located outside the upstream and .:own-
stream limits of the main dam.
5 -HYDROLOGIC AND HYDRAULIC CONSIDERATIONS
Tables 3~ 3A, 4 and 5 list the provisional hydrologic and hydrauiir: par-ameters
to be used. Table 6 det~ils pr ... limfnary freeboard requirements whne an
example is worked out tn TaBle 5A to~ca1culate freeboard requirements.
5 . 1 -GP (t era 1
Figures 1~8 illustrate the storage capacity at eacn ~am site for different
water levels .
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5.2 -Sizing of Hydraulic Components
(a) Power Conduits -For uam schemes the sizes should be based on the
maximum velocities listed in Table 5. For long tunnel schemes the
dia~eter should be determined such that the cost of energy is minimized.
(b) Diversion System -The cofferdam-diversion tunnel system is to be sized
as follows:
1. Size ·diversion tunnel for maximum velocity (Table 5) for the design
diversion flow. Calculate head loss in the tunnel and fix top of
upstream cofferdam (allow 10' freeboard).
2. Calculate height of downstream cofferdam from approximate stage-
discharge relationship.
(c) Spillwax -Size spillway to accommodate the Project D~sign Flood shown
in Table 3/3A. Utilize supplemEntary emergency spillway if necessary.
All service spillways should be fitted with downstream stilling basins.
The capacity of the structure should be checked for the PMF with a
reduction up to 91 in freeboard (Table 6). The energy to be dissipated
should not exceed 45,000 hp per foot width under PMF conditions.
6 -ENGINEERING LAYOUT CONSIDERATIO~~
~~~_,s..
Table 7 lists the components that should be incorporated in the engineering
layouts and describes the types of components to be used. This table shotild
be used as a guide for a 11 1 ayouts. ,.
7 -MECHANICAL
7.1-Powerhouse
(a) Number of Units
In general, a decrease in the number of units will result in a reduction
in powerplant cost. For preliminary studies assume:
unit capacities lOOMW to 250MW;
-minimum number of units = 2;
-maximum nunJb(~r of units = 4.
(b) Turb"'ines
Assume rated net head approximately equal to:
minimum net head~ 0.75 (maximum net head-minimum net head).
For rat,ed heads above 130 ft. units will be vertical Francis type wi t.h
s·t.af:l !;piral cases. For lower-heads assume vertical Kaplan units.
The tLrbines will be directly connected to vertical synchronous
generator~.
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7.2-Overflow Spillway
The. spillway gates will be fixed wheel vertical lift gates operated by
double drum with rope hoists located in an enclosed tower and bridge
structure. Maximum gate size for preliminary design should be: ·
-width ----~--· _, __ 50 ft.
-height ---------60 ft.
Provide 3 ft. freeboard for g3tes over maximum operating water level. The
gates will be heated for winter operation.
7.3-Miscellaneous Mechanical Equipment
Cost estimates should provide for a full range of power station equipment
including cranes, gates, valves, etc.
8 -ELECTRICAL CONSIDERATIONS
8.1 -Powerhouse
Generators will be of the vertical synchronous type. Separate transformer
g~lleries will be provided for main and station transformers. Provision
will be made in the cost estimates for a full range of miscellaneous
operating and control equipment including where necessary allowance for
remote station operations.
8.2-Sw~~chyard and Transmission Lines
Switchya~d should be located on the surface and as close to the powerhouse
as possible. The size of the yards should be approximately 900 x 500 ft.
Cost estimates should a 11 ow for trans'" iss inn 1 i nes and substations (see
Table J).
9 -ENVIRONMENTAL CONSIDERATICNS
For this step, environmental considerations will be limited to the effect
on fisheries. In order to avoid a severe detrimental impact on the fisheries
habitat tentative water level fluctuations and downstream flow release
tonstraints have been developed and should be adhered to.
9.1 -Flow Constraints
Table 8 lists preliminary values of minimum flows required downstream of any
development at all times. The lower flows are based on preliminary as·sess-
ment of requirement of resident fish while the higher flows are estimate~
anadromous fish needs.
9.2 -Water Level Constraints
Daily reservoir level fluctuations should be kept below 5 ft. whi1e
seasonal drawdown should be limited to 100 to 150 ft.
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TABLE 1 -Monthly Variation of Energy
and Peak Power Demand
1. Monthly energy variation as a fraction of the total firm energy:
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
.086 .101 .109 .100 .094 .086 .076 .069 .067 .066 .070 .076
2. Monthly variation of peak demand as a fraction of the installed capacity:
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
.80 0.92 1.00 0.92 0.87 0.78 0.70 0.64 0.62 0.61 0.64 0_70
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GENERAL CONDITIONS
1. Dam Type
2. U/S Slope
3. \)/S Slope
4. Gen,eral Foundation Conditions
5. Required Foundation Excavation
(in addition to overb:.rrden)
6. Required 'Foundation Tre.atment & Grouting
7o Seismic Considerations
(MCE = Maximum Credible Earth1uake)
8. Powerhouse Location
9. Permafrost
10. Construction Material Availability
11. Remarks
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TABLE 2
GEOTECHNICAL DESIGN CONSIDERATIONS
DENALI
Earth-Rockfi11
4:1 (H/V)
4: l .
0
All structt···es would. have soil
foundationso Depth to bedrock
is believed to be 200'+. Inter-
stratified till and alluvium
foundation materia_l, local
liquefaction potential,. 40'+
alluvium in valley.
Abutment
Ch, nnel
Total Excavation Depth
Core Shell
30 I 10 I
70 I 50 I
Assume core-grout in five rows of
holes to 70% of head up to c maxi-
mum of 3oo•. Probable drain curtain
or drain blanket unde·r downstream
shell. Foundation surface-no
special treatment.
High exposure, no known site faults.
MCE = Richter 8.5 @ 40 miles.
U\Jderground powerhouse unsuitable.
> 100' deep in abutments, probable
1 enses under tiver.
No borro\t/ areas identified. Assume
suitab"i e materials are available
wi·thin a five-mile radius. Proces ...
sing of impervious material will be
required.
Based on Kachadoorian, 1959.
MACLAREN
Earth-Rockfill
4: l
4:1
Assume soil foundations. Depth
to bedrock estimated at ZOO •.
Compressible, pe.rmeabl e and
liquefiable zones probably er.ist.
Unknown. Assume same as for Dena 1 i.
Assume same as for Denali.
High eKposure, no known site faults.
MCE = 3.5 @ 40 miles.
Underground powerhouse unsuitable
Probably> lOOt.
Assume Si\me as for Denali.
No report on site= Parameters based
on regional geology.
NOTE: 1) Actual est.imates on \.alatana & Devil Canyon hav~. been taken from overburden contour· maps.
2) Data compiled prior to Ja'nuary 1, 1981. Estimates made after this date have used updated excavation criteria.
VEE -
~arth-Rockfill
2. 25:1
2:1
River alluvium 12F', drift or talus on abutments
is 1(}-40' thi.ck. Saddle dam located on deep
oermafrost alluvium.
'
Assume: Core -Remove average of 50' of rock
Shell -Remove top 10• of rock
Assume ·~routing same as for Watana. No special
tr.Qatment under-shell. Assume extensive ~and
drains in sa4dle dam permafrost area.
High exposur~, no knm'in site faults.
~CE = 8.5 @ 40 miles.
Unknown. Assume suitable for underground with substantia 1 rock support.· ·
> 60' in saddle area, sporadic in abutments.
Assume available 0.5 to 5 mile radius.
Impervious will require prOcessing~
Based on USBR studies.
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GENERAL CONDITIONS
1.. Dam Type
2. U/S Slope
3. 0/S Slope
4.. Generitl Foundation Conditions
5. Required Foundation Excavation
(in addition to overburden)
6.. Required Foundation Treatment & Grouting
7. Seismic Considerations
{MCE = f4aximum Credible Eart . ..:tuake)
8. Powerhouse Location
9. Permafrost
10. Construction Material Availability
11.. Remarks
TABLE 2 (cont'd)
GEOTECHNICAL DESIGN CONSIDERATIONS
.SUSITNA III
Earth-Rockfil1
2. 25:1
? + 1 ....
Unknown but rock probably over 50'
in deptho Possible permeable
compressible and liquefiable strata.
Assume same as fm" Wa tan a.
Assume grout and drain system full
width of dam, dependent on founda-
tion quality. Drain gallery & drain holes.
High exposure. MCE = 8.5 @ 40 miles.
Also near zone of intense shearing.
Unknown. Assume suitable for under·-
ground with substantial rock supporte
Probably sporadic and deep.
Assume available within five miles.
Processing similar to that at
Watana.
No reports avail~~le. Parameters
based on regional geology of the area.
WATANA
Earth-Rockfill or concrete arch
2.25:1 (for earth)
2:1
Abutments -assume 15' _overburden(Oa)
Valley bottom -4B-78i alluvium .
Assume 70'. Right bank upstream-
approximately 475' deep relict
channel on right bank, upstream of
dam site.
Core: Remove top 40' of rock
Shell: Remove top 10' of rock
Extensive grouting to depth ::; 70%
of head but not to exceed 300' •
Drain gallery & drain holes.
MCE = Richter 8.5 @ 40 miles or
7.0@ 10 miles. ·--
Underground favorable, extensive
support may be required ..
> 100 feet on left abutment. More
prevalent and deeper on north facing
slopes.
Available within 0-5 miles.
Processing required.
Based on Corps studies and 1980
Acres exploration.
HIGH DEVIL CANYON
Earth-Rockfil 1
2. 25:1
2.1
Assume 30-60' overburden and alluviu~.
Core: Remove top 40 • of rock
ShE:!ll: Remove top 15' of rock
Assume same as for \1atana.
Same as for Watana.
Probably favorable for underground but assume
support needed.
Sporadic, possibly 100' +a
No borrow areas defined.. Assume avai1ab1f;
within '5 miles.
No geotechnical data available. Parameters
based c·H regional geology.
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GENERAL CONDITIONS
1~ Dam Type
2. . U/S s·iope
3. D/S Slope
. 4. General Foundation Condi'tions
5. Required Foundation Excavation
(in addition to overburden)
<l
6.. Required Foundation Treatment & Grouting
7. Seismic Considerations
(MCE = Maximum Credible Earthquake)
8. Powerhouse Location
9. Perrnafrost
10. Construction Materi?ll Availability
il. Remarks.
TABLE 2 ( cont' d)
GEOTECHNICAL DESIGN CONSIDERATIONS
GE'J IL CANYON
Concrete arch or gravity
DEVIL CANYON
Rockfi1l
2. 25:1
2:1
Assume 35' alluvium in river bottom. Shears and fau1t zones in both abut-
ments, 35-50' of weathered rock. Saddle dam overburden up to 90' deep.
Assume excavation for spillway totals ~o~ to sound rock on valley walls.
Remove 50' of rock. Extensive
dental work and shear zone over-
excavation will be required.
Saddle dam: Excavate 15' into rock.
Extensive grouting to 70% of head,
limited to 300'. A.llow for long
anchors into rock for thr·ust blocks.
Extensive dental treatment. iJeep
cutoff under saddle dam, 15' into
rock.
Same as for Watana.
Favorable for underground powerhouse,
assume moderate support.
None expected, but possibly sporadic.
Concrete aggregate within 0.5 miles,
embankment material ... assume \-Jithin
3 miles.
Based on USSR, Corps and 1980
Acres exploration.
Core: Excavate 40' into rock
Shell: Excavate 15 1 into rock
Allow for sw--face treatment.
Saddle dam: Excavate 15' into rock.
Extensive grouting to 70% of hea~,
limited to 300•. Extensive dental
treatment under core. Deep cutoff
under saddle dam, 15' into rock.
Same as for Watana.
Favorable for underground po\'Jerhouse,
assume moderate support.
None expected, but possibly sporadic~
Concrete aggregate within 0.5 miles,
embankmer~ material -assume within
3 miles~
Based on USBR, Corps and 1980
Acres exploration.,
PORTAGE CREEK
Concrete gravity
Unknown -assume same. as for Devil Canyon.
Rock type is similar to Dev1l Canyon, so
assume foundation conditions are ';;imilar.
Assume same as Devil Cc:myon. ·
MCE :: Richter 8.5 @ 40 miles or 7.0 at lO miles.
. --
Probably favorable for underground powerhouse,
assume moderate support.
None expected, may be local areas on north·exposures
or in overburden.
Unknown -expect adequate sources 2-5 miles
downstream.
No previous investigations are available on this
site.
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I Table 3: HYDROLOGIC DESIGN CONSIDERATIONS
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High Devil De·. 11 Portage Tunnel
Parameter Denali Maclaren Vee Susitna III Watana Canyon Canyon Creek Alternati\'e Remarks
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Catchment area-sq .mi • : 1,260 2,320 4,140 4,225 5,180 5,760 5,810 5,840
Mean annual flow-cfs: 3,290 4,360 6,190 6,350 8,140 9,140 9,230· 9,230
I Spillway design flood-cfs: 89,800 106,000 133,000 137,000 175,.000 198,000 200,000 200,000 175,000 1:10,000 year
flood peak
without routing
I Construction diversion
flood cfs: 42,500 50,000 63,000 64,600 82,600 93,500 94,400 20,000* 20,000* 1:50 year· flood
I peak
50 year sediment
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accumulation Acre-ft: 290,000 243,000 162,000 165,000 204,000 248,000 252,000 assumes no up-
stream develop-
ment
I *Considered only as second develop,nents after upstream dam( s) is built
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Parameters
Spillway design flood-cfs
Construction diversion
'i PMF for checking design-
cfs
Aduendum
TABLE 3A-Revised Design Flood Flows for Cumbined Development
Scheme 1 Scheme 2
(l~atana & Devil Canynn) 1 High Devil Portage )
\Canyon & Creek & Vee
115,000 135,000 145,000 150,000 105,000
89,100 20,000 99,100 20,000 71,200
235,000 270,000 262,000 270,000 189)]00
Note: This table is based on Acres Flood Frequency Analyses and supercedes
Ta.b1 e 3 for vJatana a,nd Ht gh De vi 1 Canyon first deyel opments.
Remarks
1:10,000 yr fT~od
routed through. tthe
reservoir at FSL as
in Table 4
Subsequent develop-
ments enjoy re~u1ation
by upstream
reservoir(s).
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Table 4: SITE SPECIFIC HYDRAULIC DESIGN CONSIDERATIONS
Parameter
Reser·voir Full
Supply Level -ft
Dam Crest Level -ft
Average Tai 1 Water
Level -ft
Installed Capacity -MW
Maximum Power Flow -cfs
~H nimum Compensation
Flow -cfs
Low Level Out1et
Capacity-cfs***
Denali
2,540
2,555
2,405
50
5,400
600
,300
Maclaren Vee Susi tna III
2,395 2,330 2,340
2,405 2,350 2,360
2,320 1,925 1,810
10 230 330
2,000 8,300 9,000
1,200 1,500 1,500
4,700 8,300 10,000
*Considered -only as second developments after u/s dam(s) is built.
**Inc 1 udes 4 • high wave wa 11 on top of dam.
***Empties reservoir to h perce:.t capacity in 12 months.
Watana
2,220/
2,000
2,225/
2,060
1,465
800/400
18,000/
11~000
2,000
20,800
High Devil
Canyon
1,750
1,775
1,030
800
18,000
2,000
15,t:OO
Devil
Canyon
Portage*
Cree"
1,020
1,465 1,030
(rock fi 11)
1,459
{concrete)**
880 8~J
400
10,000
2,000
10,600
150
15,000
2,000
9,300
Tunnel*
Alternative
2,200/
1,475
2,225/
1,490
),465/
1,260/
900
8,400
1,000
20,800
{\~at ana}
Remarks Tunnel
Alternative Only
Tunnel alter-
native consists
of Watana. aPid
re-regul ati on dams
See above remarks
Watana/Re-regula-
ti on dam/Devi 1
Canyon, respec,.
ti vely
In Tunne 1 h.otwr-Jen
re-regul ati on and
Devil Canyon Power
House
In reach between
tunnel outfall at
Devil Canyon
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Water Passage
TABLE 5 -General Hydraulic Design
Considerations
Maximum vel~cities-fps: Steel penstocks: 20
Power tunnels -lined: 15
Tailrace -lined: 15
unlined: 10
Diversion tunnels -lined: 50
.·
For tunnels
less than 5
mi :J.es 1 ong ..
For the tunnel-alternative scheme (tunnel length greater than 5 miles}
optimize velocity with respect to cost of tunneling and energy loss in
friction.
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TABLE 6 .. , Preliminary Freeboard Regui rement
Parameter
1. Design Conditions
Dry freeboard -ft.
Wave run up & wind set up -ft.
Flood surcharge over full supply
1 evel (JSLl -_ft.
Allowance for post-construction
settlement
Total Freeboard -Ft.
Dam Crest Level -Ft.
2. Extreme Conditions fa~ Checking D~sig~
a) Seismic slump
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b) PMF surcharge over FSL
allowable
Rockfill/
Earthfill
Dam
3
6
5
1% dam height
14'
FSL + 14'
+ 1% dam heignt
1~% of dam height
14 1
If seismic slump~ 14' design conditions fix dam crest level.
Concrete
Dam
3
6
5
nil
14'
FSL + 14'
nil
14'
If seismic slump> 14' dam crest level = FSL + sefsmic slump t 1% allowance
for post-construction settlement,.
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TAB~E 6A -Calculation of Freeboard
Requirement at Devil Canyon
F S L = 1445' Dam height
Design Conditions
Dry freeboard
Wave run up, etc.
Flood surcharge
Height of dam
1% of he1 ght for post-construction
settlement
Dam Crest Leve1
Extreme Condi_ ttons
a) Seismic slump (1~%)
Seismic slump < 14'
Thus, dam crest level remains
the same as calculated above.
b) PMF condition
Maximum allowable water level
= 600'
Rock fill Dam --
3'
6'
5'
600'
6
1445 + 14 + 6
= 1465'
9'
1445 + 14
= 1459'
Concrete Dam
31
6'
5'
600'
nil
1445 + 14
= 1459'
nil
1445 + 14
~ 1459' .
~-----------------------
...
--
0
Components
Dam
Spil htay
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Power Facilities
Intake:
Pm'ler Tunnel:
Penstocks:
Powerhouse:
Tail race Tunnel :
Lm·1 Level Outlet l~orks
Intake and Tunnel:
Constt~uction Facilities
U/S & 0/S Cofferdams:
Diversion Tunnels:
Access
Road Access:
Transmission Line
Local
--------:-
Denali Maclaren Susitna II f High Devil Can,xoJt Devil CaJl~Q'l
(-Conventional earth/rockfill ---------------·----------7>) Conct~ete
Watana Vee Tunne 1 A ltennutivt!s ........ ..___
Ear"th/rockfi]l~
(-~e•·vice: Gated, open chute with downstream stilling basin ----------_________ ,_,_.~~~
~Emergency: (if requfr•ed} as above \'lith downstream flip bucket---------·-------------··""~
(:--Single ~level --7 ~ r-tultilevel --------------
r-S!ngle t~oncret£l."} ~--Hinimllm of t\'IO, concrete 1 ined -l1ned
---~~ T\'IO par·tially, 'lined
tunne 1 s ( 1/3 ~tan c.
1 ined, 1/3 sh~'.t
creted, 1/3 t~f.t::tined)
~Steel lining \'/here necessary (near U.G. PO\'/erhouse}(length=l/5 turbine head) -------------~-, ·-~--~
{--Underground if feasible------·.,__-----·-------·------~-----------~·-.,.. .. -~
<-One lined/unlined--) -c:--T\oJO lined/unlined----·-----------------------"""'.,.,._, .. >
~-(Lined or unlined -based on cost/energy loss optimization-.· ~ -~~~)
~One or t\<10 \'lith gates -use diversion tunnel{s) H possible--------------·-----------""'""'~
r-Eadh or rockfill ----------------------ll.. <!.--Fill or -4 <-Fill ---~~ -,... ,~·cellular ·
<--Mini111um of t\'10 --------------------
<--To Denali Highway--) (---·to Gold Creek-------~
To Cantwell along <-Denali lligiMay ~ <..-to Gold Creek --------
--------·----------~~-->
-----·------------
------------
f.-Roads/tunnels and bridges. as required -----·~-·----
\
-
•
-..... -
TAGLE 7_ (cont'd)
Comp.Q_nen ts
Compensation Flow
Outlet
Surge Chambet·
--- --- -----~-
Haclaren Vee --Susitna II I Hatana High Devil tan.v.on !Jevil Canyon Tunnel A 1 ten1.r.U.ives -.-.:::..-:.·:.ljPlloo..-o#
<-Independant intake \<lith control valve discharging through low level outlet \'larks or independent cf)nduit _ ___,.., .... ..,.7
~ Upstt·eam surge tank required if net head on machines < 1/6 of distance between t·eservoir and machine----...... ~
~Downstream stwge tank is required if tailrace is pressur·ized -------------~-----
~Size diffet'ential surge chambers for all locations \<~here t'e'•lUired ----------------------."'"""'"7
NOTE: Portage Creek development will be similar toM?· L,r,~·' :~ccpt that
.access roads and transmission li.nes will be to <<'h 'beek.
: ·.
-
-.. - - - - -.. -~ --.-- -·-- - - -
Site
Denali
Maclaren
Vee
Susitna III
Watana
High Devil Canyon
Devil Canyon
Alternative Tunnel
Scheme
TABLE 8: Tentative Environmental Flow Constraints
Required Minimum
Flow Release-cfs
With Project Without Project
Located ·· Located . ·
Downstream * Downstream*
300 600
bOO 1,200
800 1,500
800 1,500
1,000 2,000
1,000 2,000
1,000 2,000
1,000
Maximum Allowable
Flow for Daily .
Peaking Operations
CFS **
5,000
6,500
9,500
9,500
12,000
13,500
14,000
14,000
Note: * Does not apply .if downstream dam backs up to tailwater level of dam above.
** Would not necessarily apply if scheme considered did not include a substantial
amount of seasonal regulation.
•)
Remarks
In the reach
between re-reg ..
dam and tailrace
outfa11 at Devil
Canyon.
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2600
2550
-...,: 2500
l&.. -
z
0 -1-
~
IJJ
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IJJ 2450
lLJ
<..>
lt a::
::> en
0:::
60
RESERVOIR AREA (I 000 ACRES)
50 40 30 20 10 0
lN IT.l\!.. CAPACITY
~ 2400 l---+-1----~+-----+------l:-----------+---c.---r--~---'9
<t
3:
ORIGINA.
2350 ~4-------+--------~------~~----~-------r---------~
l
2300 ~~~~~~~~~~--~~~-~~--~--~~~~~~~~~~~~
0 2 3
STORAGE CAPACITY (MILLION AC. ~T.}
4 5
I
AREA AND CAPACITY CURVES
DENALI RES.ERVOIR
FIGURE l
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--------------------~--~------------------------------------------~
RESERVOIR AREA { 1000 ACRES)
0.6 0.5 0.4 0.3 0.2 0.1 0
2425 --------~--------~----~~~--~--------------~------~
-
z
0
1-2.375
§
w
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lLJ
(.)
~
~ 2350
C/)
I
-......._INITIAL CAPACITY
ORIGINAL AREA
2300~~~_.~~~~~~--~~~_.~--~~~---~~~~--~~~
0 50 100 150 200 2.50
STORAGE CAPACITY ( l 0 0 0 AC. FT. )
AREA AND CAPACITY CURVES
MACLAReN RESERVOIR
FIGURE 2
300
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20 IS 16 14 12 10 8 6 4 2 0
2400
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u.. -
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0
r-
<(
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w 2100
l.IJ
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~ a:: =>
U)
I a: w 2000 1-
<(
I 3:
ORIGINAL AREA
I
1900
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1800 I 0 2 3 4
STORAGE CAPACITY (MtLLION AC FT.) c,
I
I AREA AND STORAGE CAPACITY CURVE
SUSITNA Jl[ {i] I FIGURE 4
~·-;::~~:""
----------=---;---------~---
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------------------~--------------------------~----------------~
2200
-
~ 1900
~
~
l&J
..J
1aJ
w 1800 (.)
~
0::::
;:)
en
0:
RESERVOIR AREA ( 1000 ACRES)
0
ORJGtNAL AREA--
' -
~ 1700 ~~~~--~~--------~~--------~-----------+--~------~
<t
3: ---+iNITIAL CAPACITY
!600·~--------~~--------~----------~--------~-+--------~~
t500
_J4JOO
0 2 4 6
STORAGE CAPACITY (MILLJON AC. FT.)
AREA AND CAP.D/CITY CURVES
WATANA f-lESERVOIR
8
FIGURE 5
10
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--1
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1800
1700
1600
-...,:
LL.
-1500
2
0 -t--~
.LLI
....J
LL1 1400
w
0 ~-·· 1.1.-
a:
::l en
1300 a:
lJJ ...
~-
1200
1100
JOOO
?.5 20
0
RESERVOIR AREA { 1000 /4CRES)
~5 10 5
ORIGINAL AREA
2 3 4
STORAGE CAPACITY {MILLION AC FT.)
AREA AND CAPACITY CURVES
HIGH D. C. RESERVOIR
FIGURE G
0
1
-5
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1:
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-· :1
I
·-
RESERVOIR AREA {ACRES}
900 750 600 450 150 0
1020
920 ~--~---+--------~--·------+-------~~r--T-----r------~;
ORIGINAL AREA.
900 ~~-----+--------~--------+-------~~~. --~--~r-------~
880 J--..-----+------l-..,....__-+----:.-l---;-~~
J I '~· 860 ~~._~_.~--~._~~_.~~._~~J~· _.'---~~----~~----~._~
0 10 20 30 40
STORAGE CAPACITY ( 1000 AC •. FT.}
AREA AND CAPAClTV CURVES
PORTAGE CREEK RESERVOIR
50 60
FIGURE 8