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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
SUBTASK 8.01 -TRANSMISSION LINE
CORRIDOR SCREENING -1980
DRAFT CLOSEOUT REPORT
JP.NUARY 1981
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TABLE OF CONTENTS
General
Selection of Corridors
Method of Evaluation
Location Considerations
Relative Cost
Environmental Assessment
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1.
TRANSMISSION CORRIDOR STUDIES
GENERAL
The rapid growth of electrical energy consumption in USA and its forecast for
the next several years indicates a need for increased electrical power gener-
ating facilities and transmission capabilities.
It ·is anticipated from various estimates that the energy required byo the U.S ..
in the year 2000 will be approximately si-x times that of the year 1964 {EEI,
1968).
The high voltage transmission line is an efficient means of transporting
electrical energy at high voltage from the generating plant to consumers.
This report addresses itself to the satisfactory routing of transmission -line
and how-we reached our selected prelim·inary route.
2., SELECTION OF CORRIDORS
Let us take a look to the map of the Rai1belt (Figure lJ. The major mountain.
"'
ranges of Alaska)' Talkeetna and Chugach limit the range of choice of corridors.
The higher elevations in these mountains are completely unsuitable for trans-
mission lines·~ and there are relatively few low elevations passe~ through
these ranges~ A'l/ay from the mountains" a wide range of locations could be
considered~
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•• s . ~a~ . ~'-UNITED STATES OEPARTMJ;NT OF TH~ tNTEfUOR
ALASKA POWER ADMfNIS'fRATlOH
I THE RAILBELT
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0 25 50
S<:oJ• -Mile~ ~;;;., ....
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2 .. 1 How to tra nspart the energy to the di fferemt c i ties?·
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Figure 2 illustrates on a very broad scale, the alternatives fo~· locating
the lines: ..
2.1.1 From the project site to Anchorage
The heart of Talkeetna mountains can be avoided by:
a. The nsusitna Corridorl' \"'hich generally follow the Susitna
River. Valley. or,
b. The· "Matanuska Corridor 11 which pass to the east of the mountains
and approaches Anchorage from the Matanuska Valley.
2.1.2 From the project site to the Fairbanks area
The options of crossing the Alaska Range are limited to:
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a. The passes in ·the Nenana River drainage ·'-lThe-Nenana Cor·ridortl. ..
or
b.. Generally along the Richardson highway to the east uDelta
-Gorri dor 11 •
METHOD OF EVALUATION
The Corps of Engineers have identified potential corr'idors utilizing large
scale topographic maps and satellite photos. This invo1ved identification of
potential feasibln passes through the mountains as shown on Figure 3 ..
Aerial reconnaissance was done to determine \-Jhich of these corridors were·
feasable for constructing lines. Several were found to have "fatal flaws''
or chara-cter~istics that would preclude their use for transmission lines~ ·
Reasons for eliminating corridors ·at this stage included completely unsuitable·
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Healy
NENANA I
CORRIDOR.
ConT_·~-e--
ANCHORAGE
e FAIRBANKS
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DELTA
CORRI_DOR
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topography~ obstruction by major glaciers or excessive elevations.
The remaintng potential corridors$ ind·icated on. Figure 4 were then analyzed
in more detail. The base of the analysis was individual corridor segments
i'ndi'cated on Fi"gure 5.. For convenience, the alternative corridors and the
individual segments were numbered as shown on maps. Table 1 provides a key
to thi's numoering system. All of th.ese remaining· corridors (Figure 5) are
considered physically feasible for transmission lines.
The evaluation is -intended to identify the relativ~ advantages or disadvantages
of utili.zing the alternatives for transmission lines ..
3 .. 1 _$teps in evaluation
1. Descript·ion and invento·ry by ?egment of the key resources that would
be impacted by a transmission line ..
2. Evaluation of probable impacts of l?cating, building, and operating
transmission line for each segment.
39 Determination of relative cost of reliability for his utilizing the
alternative corridors.
· 4. Summarization of advantages· or disadvantages from the viewpoint of
envir'onment, engineering, costs, and reliability nf service ..
5. Selection of preferred corridors.
3-2 A .. P .. Ad .. Inventory
(tne descri'ption and inventory of evaluation of impacts are reported in
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more detail. in the. APAd environmental assessment~ with only summary
information presented in this report .. The inventory·grouped data under
nine broad £ategories:
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PROPOSED
CORRIDOR~ ...
..
. . .. .... . . -. . . .. . : . ~ ... . . : . .. ·;. ~ .. . .
FAIRBANKS
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DELTA 'CORRIDOR
DEVIL CANYON PROJECT ..
AL TE'RNATIVE
TRANSMISSIC~N CO_RRIDORS
l J
Appendix f
FIGURE l-S
1-.11
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• Poxson
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DEVIL CANYON PROJECT
TRANSMISSION ·
CORRfDOR SEGMENTS
Scale in mites .
e~·
50 75 100 125
A.P.A:-Morch t97~
Appendix 1
FlGURE 1,...~
1-13
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Key to Alternative Corridors and St~grnents
Corridor
Susitna 11
Susitna #2
Susitna #3
Susitna #4.
Matanuska #1
~iatanuska #2
Nenana #1
Nenana #2
Nenana #.3
N'enana #4
Nenana #5
Delta #]
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-----·-·.
Segments
of Corridor
Susitna Corridors
1. 3, 7
lt 2, 7
1. 4, 5
1, 4, 6, 8
lvfatanuska Corridors
8, 9; 20. 22 .
8. 9 , 18 • 21 , 22'
Nenana Cc:-ridors
7, 10 ll 13, 16
.. 7, 10, 12, 14,_
7 .. 101 12, 14,
B. 9, 11, 14,
8, 9, 11, 14,
Delta Corridor
8, 9, 18.
( TAF3l.t:. 1)
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19
~-----·-· -~
17
15,
15,
17
16
16
Approximate
Total Milea~
136
140
129
147
258*
385
198 .
220
231
223
212
280
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4.
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9.
Topography of Geology
Soils
Vegetation
Wildlife
Climate
Existing Developments
Ownershio of Land Status .
Relation to Existing Rights uf \·Ja"y
Scenic Quali.ty of Recreation
The probable impacts are identified and described under five broad
categories in the environmental assessment:
1., Soil
2 .. Vegetation
3. Wildlife
4. Existing Developments
5. Scenic Quality and Recreation
LOCATION CONSIDERATIONS
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Corridor location objectives are to obtain an optimum combination of reliability
and cost wit!;1 the fewest environmental problems.. In many cases these objectives
are mutually compatible. :
Throug~out the corridor evaluation the question arises of whether it is mot .. e
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desir~ble to place lines relatively close to exi-sting surface transportation
fac11ities or to pioneer new corridors where the line would be seen by fe\¥
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4.1 Major factors considered in the evaluation of alternative corridors:
4.1.1 Climate and Elevation
~linds ~ icing, snow depth and low temperatures are very important
parameter_s in transmission design, operation and reliabili·ty.
· Elevations above about 4000 feet in· the Alaska Range of Talkeetna
mountains are unsuitable for locating major transmission facilities.·
Significant advantages in reliability and cost are expected if the
line is kept \'Je11 below 3000 feet in elev~tion.
4.1.2 Topography
. Topography plays a great role in corridor location; it affects the
following:
a) construction, inspection of maintenance cost
b) visual impacts
c) reliability
Transmission costs rise ~ramatically in areas of broken or steep
terrain.
4.1~3 Soilsand Foundation
Soi 1 condits require designs of tm'/er foundations that are com-..
patible with the characteristic beha1ior of soils.
4~1.4 Vegetation
Heavily forested areas in the valleys. would require essentia11y
continuous clearing of the transmission right of way, yet it has
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the advantage of shielding the line from view. At higher elevations
there would be li.ttle impact on vegetation· but line visibility is
high.
4.1.5 l-Jildlife
The major consideration for wildlife.is the e.xtent to which the
transmis~ion lines change the acce:ss to 1ar.d by peop1e. New
corridors and new access roads terid to encourage public use and
thus increase pressure on fish and wildlife.
4.1.6 Visual Aspects
Existing criteria provide for utilizing natural vegetation and
topographic re 1 i ef as a shie 1 d, minimi zi·ng crossings over ro~ds
and otherwise utilizing route selection and orientation techniques 1<1
to minimize visibility. ,•
4.1. 7 Socio-Economic Aspects.
Land status, ownership, use and value are important factors in
locating the transmission corridors.
Hunti·ng lodges, tourist accomodations, and facilities with high
scenic uses or values such as parks, scenic v·ie\'Jpoints, recreation
areas, ~tc., should be avoided or skirited by trans.mission corridors ..
4.1.8 Distance
Economics dictate that line distances should be kept as short as
possible while. recognizing other criteria.
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RELATIVE COST
Rough reconnaissance cost estimate$ were made for transmissibn lines in the
alternative corripors to illustrate relative costs.. The estimates are sum-
marized on Table 2.
The following are considered in the relative cost evaluation:
1. Susitna corridors based on 345 kv~ double ctrcuit lines.
2. Nenana and Delta corridors are based on 230 kv. double circuit lines.
Investigating Table 2~ it is obvious that corridors S-1 (from dam sites to
Anchorage)~ and N-1 (from dam sites to Fairbanks} are the most economical
ones..
ENVIRONMENTAL ASSESSMENT
Table 3 shows a·relative assessment of the different corridors regarding:
1. Environmental impacts
2. Cost estimates
3. Reliability
Note, lower ranking on the table indi.cated fewer· adverse impacts. It is
obvious thus, that corridors S-1 and N-1 are the best ones.
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Length, miles
Max. elevation, fee.t
Clearing, . miles
Med. heavy
Light
None
Access Roads, miles
New roads
4-\"/heel drive access
None.
Tower Construction, tniles
Heavy steel
Normal
Comparative Cost, $1,000
Clearing
Acces's
Transmission Lines
Total ...
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Relative Transmission Construction Cost for
A.ltel.·nali:ve Corridors -Ueper Susitna to Anchot"~
Susitna Corridors~ -----.._.,;,;..:__ s -1~
166
2,100
166
0
122
44
44 ~
122
3,000
8.,000
82,000
93,0.00
S-2 S-3
':'
. 170
2,100
146
10
14.
0
126 .
44
44
126
3,000
8,200
84.000
95,200.
' 132
10
17
12
122
25
68
91
3,000
9,500
81,300
93,800
s -4
164
2,200
142
13
9
32
' 104
28
62
102
3,000
10,900
82,200
?6 ,100
l\fatanuska· Corridors
]..,{ - 1 l\t -2
258
3.000
166
17
75
84
138
36
.· 30
228
600
191900
132.700
153,200
385
4,000
228
157
64
290
31.
94
291
1.100
«'7,200
l~t .. , 200 -<i(dii. 500
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. -(~ontinued) Relative Transmission Construction Cost for
·Alternative Corridors -Upper S~sitna to Fairbanks
Nenana Corridors Delta Corrido-1!" N-1 . , N-2 . N .,.. 3 N-4 N - 5
D
Length, miles 228. 250 261 223 212 280 Max. elevation, feet Z,400 4,300 4,000 4,000 4,300 4,000
Clearing) miles
Med. heavy 125 139 127 99 . 111 114 Light 0 0 0 0 0 Zl None 103 '111 134 124 101 145
Access Roads, miles . New roads 0 136 50 96 182 168 4-Wbeel drive acces.s 97 22 119 97 0 82 None 131 102 92 30 30 30
Tower Construction, miles / »
<: Heavy steel 155 194 188 121 127 198 Normal 73 56 73 102 85 82
Com:earative Cost, $1,000·
, .....
Clearing 400 400 400 200 300 400 Access . 7,800 21,800 17,400 20,500 24,800 27,300 Transmission lines 77,200 84,900 88,500 • 75,000 71,400 94,800 f· Total · • 85,400 107,100 106,300 95,700 '16, 500 122,500 v/
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\ Corridor Analysis Project Power to Anchorage/Cook Inlet Are~
Susitna Corridors 't lwlatanuska Corridors-
Analysis_ Factor: s -1 s -·2 s ... 3 s -4 M-1 M ... z
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Length~ miles 166 170 159 164 258 385
Max. elevation J feet 2, 100 2) 100 3.800 2,200 3.000 4,000
Ranking 1 1 2
..
1 3 4
·Environmental If!!Eacts ..
Soils 1 z 1 ·1 .. 2 2
Vegetation 2 3 1 3 4 ·s
\'lildlife ~ ' ,. '• 1 2 3 3 4 . 3 E . ti , " XlS ng aeve1opments 3 3 2 1 3 3
Scenic quality /recreation:
Developed areas 3 3 2 1 3 3
Remote areas 1 2 3 4. . 4 3
Ranking 1 3' 1 3 . 4 4 ..
Costs
Construction 1 , 1 2 1 3 4
Operation and maintenance 1 1 2 1 3 3
Ranking 1 1 2 1 3 4
Reliabili!i': '•
Exposure to hazards 1 l 2 1 2 3
Ease of repai~· 1 z 2 • z 3 3
Ranking 1 2 '3 ~ 2 4 4
...
-Summary Ranktng .. " 1 2 3 . 2 4 4
. :t: -l ,::Z::, (preferred 1 )>"'0 w 00"'0 corridor) wr-ro
(TIJB LE m::s 5) 0. :X: ......
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Corridor Analysis -Project Power to Fairbanks/Tanana Area
Analysis Factor: ,;
Length, miles
Max. elevation, fe·et
Ranking-
_¥.nvironmental Impacts
SoBs
Vegetation
Wildlife
Existing developments
Scenic quality I recreation:
Developed areas
Remote areas
R~king
Costs
Construction
Operation and maintenance
Ranking
Reliabilitr
Exposure to hazards ·
Ease of repair
Ranking
Summary Ranking
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N -1
228
2,400
1
1
2
1
3
3
1
1
1
1
1
1
'1
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(prefe.rred
corridor)
Nenana. Corridors
N -2
250
4,300
3
3
2
3
2
2
3
3
4
4
4
4
4
3
4
N -3
261
4,000 . 3
2
3
2
2
2
2
3
2
2
2
3
2
2
z
( 7-A BL£'
N -4
223
4,000
'1. c of..l i:)
2
2
2·
3
2
1
2
2"
3
3
3
2
3
2
z
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N -5
212
'4,300
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3
1
3
1
1
3
1
5 ..
5 ..
5
4
4
3
3
.
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Delta Corrid~l"
D
280
4~000 --=
3
3
3
3 , ....
3
2
3
6
3
4
4
3
3
4
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ROUTE SELECTION
The preliminary. line routing is shown on Figures 6 and 7. Figure 6 shows
the line with respect to the other existing facilities!/ highways, railroads~
etc.
Figure 7 shows only the center line of the preliminary line.
Three cQrridors \'Jere identified on USGS maps of scale 1:250,000~
The three .corridors are between:
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1 -Anchorage, Willow and Palmer. (Figure 8)
2 -Damsites to the intertie at Healy. (Figure 9).
3 -Healy to Fairbanks. {Figure 10)
The center lines of the preliminary routes were also plotted on the maps.
These maps vJere made available for preliminary bi.ologic and environmenta1
studies.
For detailed study of the route, location center line is plotted·on large maps
of scale 1:63,360 (one which equals one mi1e), and under further refinement
pending input from other studies. About fourty of such maps are.done~ as an
illustration, see Figure 11 •
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ROUTE SELECTION CRITERIA
I &WIRGNMENIAL: .
1 -SCENIC QUALITY -RECREATION
2 -CULTURAL RESOURGES
3 -vii LDLIFE
4 -VEGETATION
5 -:. SOIL
6 -EXISTING DEVELOPNENT -SOCIAL
II COSTS:
1 -LENGTH
2 -TOPOGRAPHY
"
3 -ACCESS ROADS
4 -CONSTRUCTIO~
5 ... OPERATION AND MAINTENANCE
6 -LAND 0\'lNERSHIP
III ENGINEERING:
1 -RELIABILITY -2 -EASE OF REPAIR
3 -: TYPE OF TOWERS
4 -FOUNDATION
5 -SEISMIC
6 -LOADING
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CLEAR MEWS
A LASKA
RAN'GE
,--.------
1
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1 MT. Me Kf~LEY
I . J
HEALY
.' NATIONAL PARK ~ CANTWELL
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TALKEETNA
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~-PROPOSED
DEVIL CANYON SUSITNA R.
TALKEETNA
MOUNTAINS
{ FiGURE 6)
PREUMIN ARY TRANSMISSION
ROUTE SELECTION J 138 KY .
~ ,. INTERTIE
I SCALE; l=t I 000,000
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LEGEND
-HIGHWAY
-H+ RAlLROAO
.
'
-PROPOSED 138 KV l NTERTIE
EKLUTNA
ANCHORAGE;
--PROPOSED SUSITNA UNE
t:l SUB STATION
€XISTlNG LfNE
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NE.NANA •
,---. - ------·-,
l . \
I MT. Me KIN LEY \
1
/ N ATlON AL PARK __ ,
r----..
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r-...!
I DENALI 1•
1 STATE /
I /. __ .J PARK,..
I I . I L ___ 1
FAtRBANKS
ALASKA
RANGE
VIATANA
TALKEETNA
MOUNTAINS
TALKEETNA •
WILLOW
PALMER
PT. MAC KENZlE
{ FI.GURE 7)
PREUMlNARY TRANSMISSION
ROUTE SELECT10N
SCALE: l=l ,000 1 000
LEGEND
-PROPOSED SUSITA
LINE
Cl SUB STATION
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UNITED STATES
ThtlENT OF THE ·INTERIOR
xEOI~OOICAL SURVEY
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T, t:\N.('t'-l~S.:T\,).J l,r,.;~ .,.{>v.,;-r:£
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TALKEETNA.
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