HomeMy WebLinkAboutAPA2921FINAL REPORT
REPORT No.1
OCTOBER 1985
DOCUMENT No.\2921
Alaska Power Authority =::=::::::::::::::J
CONTRACT TO '
ACCESS CORRIDOR,CONSTRUCTION
ONE AND TRANSMISSION CORRIDOR
FISH IMPACT ASSESSMENT AND
MITIGATION PLAN
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NA JOINT VENTURE
FEDERAL ENERGY'REGULATORY COMMISSION
PROJECT No.7114
SUSITNA
HYDROELECTRIC PROJECT
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Document No.2921
Susitna File No.4.3.1.9
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SUSITNA HYDROELECTRIC PROJECT
ACCESS CORRIDOR,CONSTRUCTION ZONE AND TRANSMISSION CORRIDOR
FISH IMPACT ASSESSMENT AND MITIGATION PLAN
Impact Assessment and Mitigation
Report No.1
Report by
Entrix,Inc •
Under Contract to
Harza-Ebasco Susitna Joint Venture
Prepared for
Alaska Power Authority
ARLIS
Alaska Resources
Ll'h~3.rv &lnfonnatton ServIces
J'l..l1chorage.Alaska
Final Report
October 1985
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NOTICE
ANY QUESTIONS OR COMMENTS CONCERNING
THIS REPORT SHOULD BE DIRECTED TO
THE ALASKA POWER AUTHORITY
SUSITNA PROJECT OFFICE
RlEF'ERENCES "•••••••
2 -Al:CESS CORRIDORS 'CI •••••••
1 - I t~TROOUCT ION 0 "I)..
4 -TRANSMISSION LINE CORRIDORS ..........................•..............
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An a1y sis.. . . . . . . ". . .0 • • "••••0 • • • • • • • ••0 • •..•e •0 • • •..•
Cantwell to Wata-na "lil •••0 Cl <l ••••••••
Watana to Devil Canyon .
Second ary Roads 'Ill ••••••
Railroad from Gold Creek to Devil Canyon .
Corridor Mitigation ..•..•...•....•.•.•....•~.•....•....
Impact Mechanisms and Mitigation Measures ....•....•....
Mon;tori ng ~0 •••••••I)e •D ••••
Impact
2.1.1
2.1.2
2.1.3
2.1.4
Access
2.2.1
2.2.2
:2.2
:2.1
TABLE OF CONTENTS
4·.1 Impact Assessment "0 •
4.1.1 Watana to Gold Creek .
4.1.2 Devil Canyon to Gold Creek ................•............
4.1 .3 Wi 11 ow to Heal y "eo .
4.1.4 Healy to Ester ".o •••••••••••••••••••••••••••••••••••
4 .1.5 Wi 11 ow to Anchorage """."I)• "<I ••••••••••
IL2 Transmission Corridor Mitigation .
4.2.1 Impact Mechanisms and Mitigation .
4.2.2 Mon;tor;ng ",0 .
:1.1 General Description ..o •••••••••••a ••••••••••••••••o •••o •••••".
1.2 Impact Assessments G ...................................•
1.3 Mitigation Plan "".
1.4 Agency Recommendat ions ....•.•......................•..........
3 -ClDNSTRUCTION ZONE ......•.•..••.•.•.•••.•...•'l;l •••••••••••••••••••••Cl •
:3.1 Impact Assessment "."".."."Co •••••••"•••••0
3.1.1 Stage I Watana Dam and Facilities .
3.1.2 Stage II Devil Canyon Dam and Facilities .
3.1.3 Stage IIIWatana Dam and Facilities ............•.......
3.2 Construction Mitigation ....••..•.•......e ••o ••••••e •••Q •••••~.
3.2.1 Impact Mechanisms and Mitigation Measures ..•...........
3 •2 I)2 Mo nit 0 r;ng . . . . . . . . . . . . .. . . . . . . .oil • • • • • • • • •lil • •..• • • • • •~0 "•
Title Page ""..
Prefal:.e II ..
Table of Contents .
List l'J.f Figures !..0 ..
List lof Tables oo .........................•6~••••O ••
Execu't i ve Summary II ..
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This report represents one volume of a four volume report series on aquatic
impact assessment,mitigation planning and monitoring for the proposed Susitna-Hydrol!lectric Project.These volumes are:
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1.Access Corridor,Construction Zone,and Transmission Corridor Fish Impact
Assessment and Mitigation Plan
2.][mpoundment Area Fi sh Impact Assessment and Mi t i gat ion Pl an
3.Downstream Fish Impact Assessment and Mitigation Plan
4.Aquatic Monitoring Plan
Impact assessments in these reports have focused on anticipated project impacts
on selected evaluation species.Project evaluation species were chosen based on
their sensitivity to change,abundance in affected habitats and human use
values.
A primary goal of the Alaska Power Authority's mitigation policy is to maintain
the pl~oductivity of natural reproducing populations,where possible.Mitigation
plann1ing follows procedures set forth in the Alaska Power Authority Mitigation
Pol icy for the Susitna Hydroelectric Project (APA 1982),which is based on the
u.s ..Fish and Wildlife Service and Alaska Department of Fish and Game mitigation
policlies (USFWS 1981,ADF&G 1982a).Mitigation planning is a continuing
process,which evolves with advances in the design of the project,increased
understanding of fish populations and habitats in the basin and analyses of
potent i alimpacts .An important element of th is evo 1ut ion is frequent
consulltation with the public and regulatory agencies to evaluate the adequacy of
the planning process.Aquatic mitigation planning began during preparation of
the Susitna Hydroelectric Project Feasibility Report (Acres American,Inc.1982)
and WelS further developed in the FERC License Application (APA 1983a,1983b).A
detailed presentation of potential mitigation measures to mitigate impacts to
chum salmon that spawn in side sloughs was prepared in November 1984 (WCC 1984).
ii
Figurl~9.Sensitive periods of instream activity for streams
crossed by the access corridor from the Denali Highway
to the Watana dam site.33
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Figur,e 1.
Figur,e 2.
Figur,e 3.
Figur,e 4.
Figurle 7.
LIST OF FIGURES
The proposed sites of the Watana and Devil Canyon Dams.
Mitigation plan development and implementation.
Option Analysis.
The vicinity of the dam sites,access corridors and
transmission line corridors.
Migration and spawning periods for Arctic grayling and
Dolly Varden in tri butari es.
Schedule for the construction of the Stage I Watana dam
and related facilities.
Sensitive aquatic habitat along the northern section of
the Watana access corridor.
Sensitive aquatic habitat along the central section of
the Watana access corridor.
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7
13
14
20
29
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FigurE!10.Plan view of potential Watana borrow sites.35
FigurE!11.Schedule for the construction of the Stage II Devil
Canyon dam and related facilities.42
FigurE!12.Sensitive aquatic habitat along the Watana and Devil
Canyon access corridors.45
Figure 13.Sensitive aquatic habitat along the western section of the
Devil Canyon access corridor.46
FigurE~14.Sensitive periods of instream activity for streams crossed
by the access and transmission line corridors to the Devil
Canyon dam site.48
FigurE!15.Plan view of the Watana dam,cofferdams,related facilities
and disposal areas.50
FigurE!16.Pl an vi ew of the Devil Canyon dam,cofferdams and di sposa 1
areas.51
iv
Figure 19.Plan view of Stages I and III of the Watana dam.
Figure 20.Borrow Site E.-
Figure 17.
Figure 18.
LIST OF FIGURES (continued)
Plan view of potential Devil Canyon borrow sites.
Schedule for the construction of the Stage III Watana dam
and related facilities..
55
66
75
78
Figure 21.Plan view of the Devil Canyon dam and related facilities.90
Figure 22.Rehabilitated Borrow Site Eo 103
Figure 23.Staged construction of transmission lines.110
Figure 24.Transmission line corridor from the Watana dam site to
Gold Creek.112
-Figure 25.The southern section of the Anchorage-Fairbanks Intertie.113
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Figure 26.The central section of the Anchorage-Fairbanks Intertie.114
Figure 27.The northern section of the Anchorage-Fairbanks Intertie.115
Figur1e 28.The transmission line corridor from Anchorage to Willow.116
Figur1e 29.The southern section of the transmission line corridor
from Healy to Ester.117
Figure 30.The northern section of the transmission line corridor
from Healy to Ester.118
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Streams to be crossed by the Devil Canyon access road and
railroad spur from Gold Creek.40
Estimated cost for water quality and fisheries monitoring
(in 1985 dollars)during construction (1990 to 2012).57
ADF&G standards for blasting near an anadromous fish stream.85
Numbers of 345kV circuits to be installed during staged
construction of the transmission lines.111
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Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
LIST OF TABLES
Access,construction and transmission line impact
mechanisms and associated mitigation.
Topics of comments from the resource management agencies
pertaining to access,construction and transmission lines.
Streams to be crossed by the Denali Highway between
-Cantwell and the Watana access road junction.
Streams to be crossed by the Watana access road (Denali
Highway to the Watana dam).
ADF&G standards for passing Arctic grayling to be used
on the Susitna Hydroelectric Project stream crossings.
ADF&G temporary stream diversion standards.
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11
16
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23
28
131...
Tabl e 11.
Tabl e 12.
Streams crossed by the Anchorage-Fairbanks Intertie.125
Streams crossed by the transmission line corridor from
Healy to Ester.
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Table 13.Streams crossed by the transmission line corridor from
Willow to Anchorage.
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135
EXECUTIVE SUMMARY
This report presents the impact analysis and proposed mitigation for the
aquatic resources in the vicinity of the access corridors,construction zones,
and transmission corridors of the Susitna Hydroelectric Project.Aquatic
impacts resulting from human activities in these regions include increases in
fishing pressure,potential migration barriers,temporary water quality
degradations and small amounts of habitat loss.Mitigation of these impacts
will primarily involve adherences to environmentally acceptable construction
practices.The increase in fishing pressure may be mitigated by special
management considerations to maintain current fish stocks.Residual impacts
are not expected to significantly reduce the productivity of the aquatic
resources of the region.
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1.0 JNTRODUCTION
The Access Corridor,Construction Zone and Transmission Corridor Fish Impact
Assessment and Mitigation Plan (ACT)is a component of the fi sheri esi mpact
assessment and mitigation plan for the Susitna Hydroelectric Project proposed
by thl~A1 aska Power Authority.The ACT contai ns an assessment of the aquatic
I
impacts associated with the construction and operation of the access roads and
transmission lines.Potential impacts on the aquatic environment from the
construct i on of the proposed Watana and Devil Canyon dams and related
facilities are also identified.The impacts and mitigation planning discussed
in th'is volume are based on information for the three stage development of the
proposed Susitna Hydroe1 ectric Project (APA 1985a).Stage I invol ves
constl"uction of the Watana dam,access roads and related facilities;during
Stage I I,the Devil Canyon dam,access and facil it i es wi 11 be bui 1t.Stage
I II c:onstruct i on will increase the crest e1 evat i on of the Watana dam.
Mitigation measures will be utilized dur-ing and after the construction of the
access roads,transmission lines,dams and related facilities to maintain the
produc:t i vity of the aquat ic popul at ions.The Power Authori ty intends to
incorporate the fi na 1 mit i gati on documents in the speci fi cat ions for bi ds and
the ccmtract documents.
I~I ~eneral Description
The Pll"oposed Watana and Devil Canyon dams are located in the upper Susitna
River Basin approximately 120 miles (190 _km)northeast of Anchorage.The
basin is bounded by the Talkeetna Mountains to the southeast and the Alaska
Range to the north and west (Figure 1).The Watana dam will be sited between
Ri ver Mil e (RM)184 and RM 185;the Devi 1 Canyon dam will be bui It 32 mil es
(53 km)downstream at approximately RM 152 of the Susitna River.
The proposed dams are in the northern porti on of South central Al aska.The
climate is typical of the transition zone,with annual temperatures averaging
about 35 0 F.Winter extends from October to May with temperatures occasionally
dropping below -50 0 F.Summers are correspondingly short and frequently rainy.
Tundra is the dominant vegetation although stands of coniferous and deciduous
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THE PROPOSED SITES OF THE WATANA AND
DEVIL CANYON DAMS
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LEGENIO
_3;-PRIMARY PAVED UNDIVIDED HIGHWAY
SECONDARY PAVED UNDIVIDED HIGHWAY
SECONDARY GRAVEL HIGHWAY
RAILROAD
RIVER
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O~~150iiiiiiiiiiiii40,IIILISICALIE;
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
-ReferenCEt:APA 1985j.Figure 1
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ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
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trees exist in areas protected from wind and at lower elevations.Isolated
areas of permafrost occur near the dam sites.
The "rater resources in the vicinity of the dams include small,clearwater
streams,lakes and the Susitna River,a large,glacial..:fed river.The Susitna
River is similar to many unregulated northern glacial rivers with high,turbid
summer flows and low,clearer winter flow.In the spring,runoff from
snowmelt and increased glacial contributions cause a rapid increase in flow
and suspended sediment concentration.Turbidity in the mainstem is reduced in
the fall when glacial contributions to the headwaters of the Susitna River
decrease.Clearwater streams are prevalent on the bluffs bordering the
Susitna River.The hydrologic regimes of the streams are typic~l of the
subarctic,snow-dominated flow regime,in which a snowmelt flood in spring is
follOllyed by generally moderate flow through the summer,with flows peaking
after rainstorm events.From October to April,low flows occur when freezing
temperatures reduce surface water contri but ions.The surface waters in the
basin are predominantly of the calcium bicarbonate type with low dissolved
solids concentrations;the water is chemically acceptable for most uses
(Balding 1976).A general overview of the chemical characteristics of streams
in thle project provided measurements of pH ranging from 6~O to 7.5 and percent
disso'ived oxygen saturation ranging from 72 percent to 99 percent (Sautner and
Stratton 1984).Most of the lakes in the basin are small and shallow although
a few larger and deeper lakes exist.The lakes generally have higher summer
water temperatures than the streams;lake-water temperatures can reach 6S oF
(Bald'ing 1976).
The clquatic resources are varied in the general area of the dams and
transportat ion corridors.The numerous clearwater streams and 1akes support
an abundant fish population.The fish species in close proximity to the
access and transmission line corridors and dam sites have been studied since
1981 (ADF&G 1981,1983;Sautner and Stratton 1984).Arctic grayling,Dolly
Varden and sculpin are known to inhabit many of the clearwater streams
(Sautner and Stratton 1984).Populations of Arctic grayling in selected
streams in the.vicinity have been estimated (ADF&G 1981,1983;Sautner and
Stratton 1984).The fish species observed within nearby lakes include Arctic
grayl'ing,Dolly Varden,burbot,whitefi sh and 1 ake trout {Sautner and Stratton
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1984).The Susitna River in the vicinity of the damsites provides
overwi nteri ng habi tat for many fi sh speci es such as Arct ic grayl i ng and Dolly
Varden and is used as a migration corridor by resident and anadromous fish
(ADF&G 1983).A few chinook salmon migrate upstream within Devil Canyon to
spawn in tributary mouths (Barrett et al.1985).However,high velocities and
turbu'lent condit ions in Devil Canyon 1i kely block the upstream passage of
other fish species.
1.2 Jmpact Assessments
The potential effects on the aquatic environment due to the three stage
development of the proposed Susitna Hydroelectric Project can be assessed by
considering the general type and schedule of activities,as identified in the
FERC License Application Amendment (APA 1985a),which will occur during
constlruct i on and operation.These potenti al aquatic impacts consi st of
changes to the aquati c habitat and/or direct effects on aquatic organi sms
which may be either beneficial or detrimental to the aquatic ecosystem.
Potential impacts to the aquatic habitats and the natural productivity of the
aquatic species that utilize habitat in the vicinity of the proposed project
are assessed through the identification of potential impacts to the evaluation
speciE~s.Arctic grayling and Dolly Varden have been selected as the primary
evaluation species for the assessment of the potential impacts in the
construction zone and access and transmission corridors.All life stages of
these species are presently abundant in the clearwater streams and lakes in
the v'Icinity of the access and transmission corridors and dam facility sites
(Sautner and Stratton 1984).In addition,Arctic grayling have high human use
value as sport fish and are sensitive to water quality degradations and
instream disturbances (Scott and Crossman 1973;McLeay et al.1983,1984).
1.3 ~itigation Plan·
The mitigation plan reflects the intent of the Power Authority to maintain the
produc:tivity of the natural aquatic population (APA 1982).The policies of
the u.s.Fish and Wildlife Service (USFWS)and the Alaska Department of Fish
and Game (ADF&G)were used to develop this approach to mitigation {USFWS 1981,
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ADF&G 1982).The mitigation plan will be developed and implemented in stages
as shown in Figure 2.Power Authority projects will avoid potential impacts
where feasible.If unavoided,impacts will be minimized,rectified,reduced
or compensated.These mitigation options will be analyzed in the hierarchical
schemt:!depicted in Figure 3.
During construction of the access roads,transmission lines,dams and
facil'ities,many potential impacts will be avoided or minimized by adherence
to the Power Authoirty's Best Management Practices Manuals (BMPM's).These
manua"ls have been prepared in coordination with the federal and state resource
managl~nent agencies and other groups to provide guidelines and recommendations
for environmentally acceptable construction practices.The manuals contain
typical practices that can be used to avoid or minimize environmental impacts
from construction,operation,and maintenance activities.Federal and state
regulations have been identified within the BMPM's.The BMPM's will be
included in the bid specifications for the design and construction of the
Susitna Hydroel ectri c Project and contractual documents wi 11 speci fy that
constl"uction activities conform with the BMPM's.
The BMP manual on Erosion and Sedimentation Control (APA 1985b)provides
guide"llines and techniques to avoid or minimize potential construction impacts
on the aquatic environment.Construction activities which may result in
erosion or sedimentation impacts,such as vegetation clearing and borrow
excavations,are discussed and general guidelines are presented for the
p1ann ii ng,des i gn,construct i on and maintenance phases of a proj ect.The
manual describes alternative site-specific methods to reduce erosion and
sedimentation and prevent water quality degradations.
The p10tential aquatic impacts associated with appropriating water will be
avoide!d or minimized by adherence to the BMP manual on Water Supply (APA
1985c).Although the actual plans,designs and installations will be dictated
by site-specific conditions,the manual depicts the environmental guidelines
and re:gul atory requi rements for water withdrawal.
The BMP manual on Liquid and Solid Waste (APA 1985d)will be utilized to avoid
-or minimize potential impacts from waste disposal on aquatic organisms.The
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IDENTIFICATION OF
IMPACTS AND GOALS OF PLAN
•
OPTION ANALYSIS
1
NEGOTIATION OF ACCEPTABLE PLAN
IMPLEMENTATION OF PLAN
1
MONITORING OF PLAN
PLAN MODIFICATION
COMPLETION OF MITIGATION
TERMINATION OF MONITORING
MITIGATION PLAN DEVELOPMENT AND IMPLEMENTATION
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 2
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ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
--_._-,------............-----------'""""!"""-------------
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PARTIAL AVOIDANCE +--....-01
,
PARTIAL RECTIFICATION~
PARTIAL COMPENSATION ~
AVOIDANCE
MINIMIZATION
I
NO MINIMIZATION
1
RECTIFICATION
I
NO RECTIFICATION
1
REDUCTION
I
NO REDUCTION
J
COMPENSATION
I
NO COMPENSATION
UNMITIGATED/LOSS
RESIDUAL IMPACT
OPTION ANALYSIS
I---~,TOTAL AVOIDANCE
~----+SOME MINIMIZATION
1-----.TOTAL RECTIFICATION
I------~SOME REDUCTION
1---~:rOTAL COMPENSATION
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 3
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ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
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manual presents various waste management techniques.The collection,
treatment and disposal of liquid wastes at project sites will conform to
techniques described in the manual to avoid or minimize water quality
degradations.Solid wastes will be handled,stored and disposed according to
manual guidelines to minimize environmental impacts.
The BMP manual entitled Fuel and Hazardous Materials (APA 1985e)contains
gUidelines to avoid or minimize potential aquatic impacts from such materials.
These materials have the potential to cause significant adverse effects on the
aquatic environment.Regulation requirements and management strategies
described in the BMPM will be utilized to safely handle and store these
materials with a minimum of adverse effect .
Potenti ali mpacts from sp ill acc i dents will be mi ni mi zed through the use of
the Oil Sp ill Contingency Pl ann i n9 BMP manual (APA 1985f).Adverse impacts
from spills of petroleum products will be minimized by site-specific spill
contingency plans specifying procedures to detect and contain sp ills.The
cleansing and restoration of contaminated areas are also described in the
manual.The manual confirms the Power Authority's intent to notify and
cooperate with the applicable regulatory agencies in the event of a spill.
Potential impacts associated with most construction,access and transmission
line activities will be avoided or minimized through adherence to the BMPM's;
residual impacts will be rectified,reduced or compensated.The Power
Authority is committed to restoring or rectifying affected aquatic habitat if
possible.Monitoring activities will verify the reductions in aquatic impacts
over the duration of the project.Compensation measures have not been
proposed.Table 1 presents the mitigation measures which will avoid,
minimize,reduce or rectify potential impacts.
Monitoring and maintenance are integral features of the mitigation process.
Monitoring will increase the flexibility of the mitigation plan and verify
that the expected level of mitigation has been achieved.Unrecognized aquatic
impacts and inadequate mitigation measures may be identified and corrected
through monitoring and maintenance activities.Construction monitoring,
conducted by an on-site Environmental Field Officer (EFO),will assure
8
1 1 J I ]1 I 1 J )1 1
Table 1.Access,construction,and transmission impact mechanisms and associated mitigation.
____MITIGATION
Impact Mechanisms
Increased Fishing
Pressures
Borrow site Excavations
~Stream Crossings
and Encroachments
Best Management Practices Manuals 1
1985b 1985c 1985d 1985e 1985f
x
x
Schedulil]9 of
Construction
Act ivlt i es
x
x
Project Policy
&Modification
of Current
Seasons/Limits
x
Water
Treatment
x
Stream Margin
Buffers
x
x
Rehabi·
l itation
x
x
Monitoring
x
x
x
Water Quality
Degradations
Oil and Hazardous
Material Spills
Water Removal
Clearing
Susitna River
Diversions
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
APA,1985b.
APA,1985c.
APA,1985d.
APA,1985e.
APA,1985f.
Erosion and Sedimentation Control
Water Supply
Liquid and Solid Waste Management
Fuel and Hazardous Materials
Oil Spill Contingency Planning
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confo'rmance with the BMPM's,regulatory permits and license stipulations
(Harza-Ebasco 1985a).Operational monitoring will verify that long-term
impacts do not cause significant degradation in the aquatic resources of the
region.
1.4 Agency Recommendations
Thi s impact assessment and mitigati on pl an is intended to be responsi ve to
resoUirce management agency concerns and recommendations.Recommendations have
been identified from agency comments on various project documents incl uding
the License Application (APA 1983a,1983b)and Table 2 summarizes the dates
and reasons for the comment submi tta1 from each agency and 1i sts the major
topic$of comments received.All agency comments pertaining to the
constl!'uct i on and maintenance of the access and transmi ss ion 1i ne corri dors and
the dams and related facilities are addressed within this impact assessment
and mitigation plan .
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Table 2.Topics of comments from the resource management agencies pertaining to
access,construction and transmission lines.-
Major Topics of
Agency Date Reason for Correspondence Comments Received
,-.USFWS 10/5/82 Letter to APA (1)Siting of access and
transmission line corridors
1/14/83 Review of Draft
Exh i bit E,FERC (2)Access road usage by
License Application non-project personnel
12/2/83 Review of License (3)Scheduling of construction
App 1i cat ion activities
12/18/84 Review of Draft (4)Hazardous material handling-Mitigation Measures
(6)Watana camp domestic water
ADF&G 1/13/83 Review of Draft supply source
Exhibit E,FERC
License Application (7)Monitoring of borrow
site activities
12/31/84 Review of Draft.-Mitigation Measures (8)Wastewater treatment
ADNR 1/13/83 Review of Draft (9)Concrete production
..-Exhibit E,FERC
License Application (10)Design of tunnel intakes
(5)Access road design
ADEC 1/21/83 Review of Draft
Exhibit E,FERC (11)Survey streams
License Application
,.-NMFS 12/31/84 Review of Draft
Mitigation Measures
1""""EPA 10/31/83 Review of License
Application
BLM 4/15/82 Response to Feasi-
bility Report
11/4/83 Review of License
Application
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2.0 ACCESS CORRIDORS
Access to the sites of the Watana and Devil Canyon dams is needed for
construction and maintenance activities.Figure 4 depicts the access
corridors to the Watana and Devil Canyon dam sites.The Watana dam site will
be accessed by road from the Denali Highway.During Stage I construction,the
closest railroad facility will be located in Cantwell at the junction of the
Denal i and Parks highways,approximately 60 miles {97 km}from the Watana dam
site.During Stage II,the Devil Canyon dam site is anticipated to be
accessed by a combi nat i on of railroad and road.The Devil Canyon road wi 11 be
built from the Watana access road to the Devil Canyon dam site.A railroad
spur and terminal facil ity is expected to be constructed from Gold Creek.
Secondary roads will be constructed to access the construction camps,
villag~s,related facilities,borrow and disposal sites.The Stage III
development of the Watana dam will utilize access corridors established during
the previous stages of cQnstr~ction.
Construction and maintenance of the access road network will impact the
aquatic resources of the region.Many of these impacts are expected to be
relatively short in duration.Construction activities such as clearing and
culvert installation may temporarily decrease water quality in streams and
disrupt existing habitat.Long-term aquatic impacts will also occur during
access construction and operation.A long-term loss of a relatively small
amount of aquatic habitat will occur at the installation sites of culverts and
low water stream crossings.Unrestrained instream activities could block fish
migrations resulting in a long-term impact to the aquatic resources.The most
significant impact anticipated is increased sport fishing pressure on
unexp'loited fish populations resulting from increased accessibility of
waterbodies in the project area.
Mitig:ation will aVOid,minimize,rectify,and reduce the potential aquatic
impacts identified for access construction and operation {Figure 3}.Many
adver:se impacts associated with construction activities will be avoided or
mi nim;zed through adherence to the BMPM's.Instream construction wi 11 be
scheduled to avoid the sensitive periods of Arctic grayling and Dolly Varden
spawn'jng (Figure 5).Management policies can be designed to minimize the
12
~;~_im._"'.__l¥i'~OIIl_'I"'l'1lli$i ''''"'''''''''w""....l'f'I'---------------!""""""'-----------------
I-'
W
1 \~\
...
•I •
1lIIL£
L£GENQ
•••PROPOSED TRANSMISSION CORRIDOR
PROPOSED DEVIL CAN'ION ACCESS CORRIDOR
PROPOSED WATANA ACCESS CORRIDOR
ANCHORAGE -fAIRBANKS INTERTlE
-1....._GOLD CREEK RAIL CORRIDOR
l 1 $J ,'I
THE VICINITY OF THE DAM SITES,ACCESS CORRIDORS
AND TRANSMISSION LINE CORRIDORS ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:Sautner and Stratton 1984.
APA 1985j.
Figure 4 ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
I ))1 1 ')r ••'t 1 ),J~
J F M A M J J A S o N D
SPAWNING
INCUBATION ~o_o_0_0_10_0_./_0_
r---.......---
_1 -.1_
_.-+-.-.......p,.-.
_.-+--.~.........-.-._.
I
......
tf:>.
MIGRATIONS
ARCTIC GRAYLING
DOLLY VARDEN
~=.:~o.::..:
---
-...-..-
.....i--._.-......_.
--+---1---
MIGRATION AND SPAWNING PERIODS FOR
ARCTIC GRAYLING AND DOllY VARDEN IN TRIBUTARIES
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:SCott and Crossman 1973.
Morrow 1980.
McLeay et aI.1984.
Figure 5 ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
impacts from increased sport fishing pressure.Monitoring activities
throu9hout construction and during maintenance of the access roads will verify
that activities are conducted with a minimum of adverse environmental impacts.
Compensation for aquatic impacts from access corridor construction and
~,..
mai ntf:mance wi 11 not be necessary unl ess a major oil spill occurs.
2.1 -Impact Analysis
2.1.1 Cantwell to Watana
(a)Description
The section of the Denali Highway from Cantwell to the intersection
with the Watana access road,a distance of 21.3 miles (35.5 km),
will be upgraded by improving one bridge,topping the road with more
gravel,and straightening road curves (APA 19859).Any needed
realignment should be possible within the existing easement.In
addition,_6 miles (10 km)of the road will be paved from the
railhead facility at Cantwell to a point 4 miles (7 km)east of the
junction of the Parks and Denali highways.Paving will avoid the
prob1em of excess i ve dust and fl yi ng stones in the commun i ty of
Cantwell.
Within the section to be upgraded,the Den~li Highway crosses
several small tributaries of the Nenana River including Edmonds
Creek and tri butari es to the Jack Ri ver.The Jack River system
contains Arctic grayling and the Nenana River system in this region
supports several other species of resident fish (Table 3).-The Watana dam site will have road access from Milepost 114.5 of the
Denali Highway (APA 1985g).,The road will run approximately 44
miles (73 kin)south to the dam and construction campsites (Figure
4).The northern portion of the route wi 11 traverse 19 mil es (31
km)of high,rolling,tundra-covered hills.The road will cross
small streams including Lily Creek,Seattle Creek,Brushkana Creek,
and additional unnamed creeks (Table 4).These northern streams,
15
~_•.",ll'I!Il~""'__------'-.----w---------------"''''1'''',-------------------
-
Table 3.Streams crossed by the Denali Highway from Cantwell to the Watana
access road junction.
Nenana River Oxbow 119.8
Nenana River Oxbow 119.5
Tributary to 118
Nenana River
Tributary to 117 .8
Nenatna River
Unnamed Creek 114.3
(Nenana R.System)
.....
-
-
Stream
Tributary
to Jack River
Tributary
to Jack River
Unnamed Creek
(Jack R.System)
Edmonds Creek
Approximate miles from
the Richardson Hwy.
132.5
132
128
121
Species Present
Arctic grayling,(whitefish)l
Arctic grayling,(whitefish)l
(Arctic grayling,whitefish)l
Arctic grayling,northern pike,
burbot,whitefish,sculpin
Arctic grayling,northern pike,
burbot,whitefish,sculpin
Arctic grayling,northern pike,
burbot,whitefish,sculpin
Arctic grayling,northern pike,
burbot,whitefish,sculpin
Arctic grayling,northern pike,
burbot,whitefish,sculpin
Arctic grayling,northern pike,
burbot,whitefish,sculpin
.....
1 (species)can be reasonably expected,but not verified
Reference:ADF&G 1978 Fisheries Atlas.Volume II.
16
......._---..,...,.--------------
Table 4.Streams to be crossed by the Watana access road (Denali Highway
to the Watana dam).
61;0'.Habitat
Stream Miles From Species Present Condition tt
(ADF&G Survey No.)Denali Highway at Crossing Crossing.....
Unnamed Creek 0.3 (grayling)2 3
(Nenana System)2.0
Trib.to Lily Cr.(I)3.0 Dolly Varden,3
.,.-.sculpin
Li ly Creek (2)3.0 Dolly Varden,3
sculpin....
Seattle Creek (3)5.8 Dolly Varden,2
grayling,sculpin
f""'"Trib.to Seattle Cr.(4)7.7 Dolly Varden 4
Trib.to Seattle Cr.(5)8.7 (Dolly Va~den,2
grayling)
Trib.to Brushkana 10.7 (grayling,sculpin)2 4-Cr.(6)
Trib.to Brushkana 11.7 (grayl i ng,sculpin)2 5-Cr.(7)
Brushkana Cr.(8)12.0 grayling,sculpin 1
......Trib.to Brushkana 13.7 grayl ing,sculpin 1
Cr.(9)
......Trib.to Brushkana 16.9 Dolly Varden,
Cr.(10)grayling,sculpin 2
Trib.to Brushkana 18.0 (grayling,sculpin)2 5
Cr.(11)
Deadman Creek (12)19.7 grayling,sculpin 5
Trib.to Deadman Cr.(13)23.0 probably none 4 5
..-Trib.to Deadman Cr.(14)23.7 probably none 4 5
Trib.to Deadman Cr.(15)24.8 probably none 4 5
~
17
..............-..-.---_._------------,--_._-------,-.----------------..--
-
......
~,
Table 4 (continued)
Habitat
Stream Miles From Species Present Condition it
(ADF&G Survey No.)Denali Highway at Crossing Crossing
Trib.to Deadman Cr.(16)27.5 (grayling,scu1pin)2 1
Trib.to Deadman Cr.(I7)28.5 probably none 4 5
Trib.to Deadman Cr.(l8)29.5 Dolly Varden,5
sculpin
Trib.to Deadman Cr.(19)31.4 sculpin 5
Trib.to Deadman Cr.(20)36.9 Dolly Varden,3
grayling,scul pi n
Trib.to Deadman Cr.(21)37.2 (grayling,sculpin)2 3
Trib.to Deadman Cr.(22)37.8 (grayling,sculpin)2 3
-
I
2
3
4
I =excellent,2 =good,3 =limited,4 =marginal,5 =poor
Ratings deduced from information presented in Sautner and Stratton (1984).
(species)can be reasonably expected,but not verified
---=not evaluated
steep contours on downstream side of road probably preclude fish from this
reach
-
....
Biological Data Source:Sautner and Stratton 1984
18
-
-
which are part of the Nenana River drainage,contain Arctic
grayling,Dolly Varden,sculpins,and probably other resident
species.The southern 25 miles (40 km)of the road will cross and
parallel Deadman Creek,a tributary of the Susitna River Deadman
Creek contains Arctic grayling,Dolly Varden,and other resident
species (Table 4).The Arctic grayling population of Deadman Creek
near the access corr;dor is est imated at 510 fi sh per mil e.The
access corridor 1 ies within 1 mile (1.6 km)of Deadman Lake which
contains Arctic grayling,Dolly Varden,lake trout,humpback
whitefish,round whitefish,burbot,and sculpin (Sautner and
Stratton 1984).Arctic grayling appear to dominate in numbers.
Watana access construction is scheduled to begin in early spring of
1990 and continue until late fall of 1991 (Figure 6).A snow and
ice road may be constructed during the winter of 1990-91 for heavy
equipment access to permit construction to proceed from both ends of
the access road.Instream activities,including the installation of
bridges and culverts,are expected to occur in the openwater season
of 1990.
Prior to actual road construction,the corridor will be cleared;
minimal impacts at stream margins will be assured by adherence to
the BMPM (APA 1985a).The Watana access corridor will not require
extensive clearing activity until heavily vegetated terrain is
encountered within 3 miles (5 km)of the construction campsite;
thi ck brush will be removed at the crossi ngs of the three Deadman
Creek tributaries nearest the Susitna River.Trees and large brush
impeding overburden removal will be cl eared by equipment ranging
from hand-held chainsaws to hydro-axes.Trees and brush will be
fe 11 ed into the access corri dor and away from waterbod i es.
Overburden and cleared material will be stockpiled at specific
disposal sites,left in place or burned.Coniferous vegetation may
be chopped by hydro-axes and broadcast;pil es of coniferous sl ash
will be burned within the first year after cutting.Deciduous
vegetation may be piled at corridor margins.The length of haul of
substandard materials will be minimized by alloWing overburden and
19
I
I 1 I ~1 )J )1 }1
tv
o
.,.'....1810 "8'."2 1'.J-'t,...t.t,•••••7 .,..U ••DEaCft.PflON I ....""••••••••
•'lflilC "calli.",UU"'IfO .-"'••"....1.•..,l1C;T caw fl••
PtlEOESIGN "-".......0 ...................
SuaSUAfACE EXPLORATIONS -I ;
LA80RATORy TESTING V Uft ·"V·..
OeSERV~110N OEvlCe UONiTOAIHO
EXISTING CAMP MOVE ......-
CAW E)l;PAH$tON --.............
I INITIAL AeeE SS ----""-I--I !,
~E~S-S--------I -~-I-"-"""--~_..~~..._----.,,
""-""...-.1----",""~
~ITIES J.-~'\i_"-t~~~_.._..__...........,........._.._.-l--c--
roeS'GN·ENGIHEEA~G ,••••••••••_•••ii••::A••'•••~•••II'•••••••_••••••••••••••••..•.•.....•.....................-.•..•-.."-
I--"""".""_1----l--PAOClJREWEHT PLAHttING.--_..-..~~,
DtVEAStOH TUNNELS +-.._--"'I"".'IDIII
"-t--+------CQFFEAOAUS --+....10 .t...,n .....10'01."••""-----r-----"~---'DAM ~"'BAHK"'ENl -r----RELICT CHANNEL -----sP1LLWAY EXCAYATiON
SPJllWAY CONCRETE
-----"-'..OUTLET fAC&LlTIE8
I ------POWER )11(1 AME --POWEA TUNNELS I
POWERHOUSE -"-r-~-to-_0A!0EI!<MlUI!Y/CAlltE 5tWTS~--ACCESSIFAQUTlU TAIlR~CE/SURGE CHAMSER ---EXCA,VAllONI'fOUtrI)AnoN WATl.ENT
"-""--f--------Au TUR81NE/OENERATORS-CONCA£JE
c--"----------~CT1IIC.I<-MfCH./flECT.SYSlEUS--~----...._---ClfOTEOHCAl _SllBAllOMS SWnCHYAAp/CONTAOl.BLDG.-OE.o/)oH'~-----------------..PAOCUAE~NT fl'L.t\MeIlIQ TRANS"iSS~N LINEa ....l"..I,••••------~NT ......0IIl".-.,..-.......TnT "NO CO-SSlOH
SCHEDULE FOR THE CONSTRUCTION OF THE STAGE I ALASKA POWER AUTHORITY
WATANA DAM AND RELATED FACILITIES SUSITNA HYDROELECTRIC PROJECT
HARZA-EBASCO
Figure 6 ENTRIX,INC.
SUSITNA JOI NT VENTUREReference:APA 1985i.
....
-
-
-.
cleared vegetation to be disposed in side borrow excavation
trenches.Clearing near the impoundment area may utilize disposal
sites within the permanent inundation area.The amounts of cleared
vegetat i on are expected to be sma 11 and are not 1ike1y to raise
hydrogen sulfide concentrations in the reservoir.Additional
disposal sites,if necessary,will be located away from floodplains
and wetlands and the disposal sites will be bermed to avoid
increased sediment and organic contributions to nearby watersheds.
The Watana access road wi 11 be constructed of gravel and have a
crown width of 24 feet (7.3 m).The road crown will be raised 2 ft
(0.6 m)to 3 ft (1 m)above the adjacent ground.The shoulders of
the road will be sloped and covered with excavated peat material to
reduce the visual impact.Road construction will predominantly use
side borrow techniques in which needed borrow material will be
excavated by scraping trenches directly alongside the road.Thus,
construction activity will generally be confined to a narrow strip,
50 ft (15 m)to 70 ft (21 m)each side of the road centerline.This
technique will minimize the requirements and associated impacts of
large borrow pit excavations.The majority of the borrow material
for the access roads is estimated to be available from side borrows;
the remainder is expected to be obtained from a few 10 to 20 acre
borrow sites located in upland areas.A mining plan,as required by
43 CFR Part 23,will be prepared for each site p~ior to the removal
of material.
Where possible,the access road stream crossings will be located
perpendicular to the stream,preferably in a straight stretch
(Lauman 1976)with low gradient and narrow,stable banks that do not
require cutting or excessive stabilization.Vehicle barriers or
guardrails will be installed at sites where there appears to be a
greater risk of accidents.
Stream crossings will require the installation of culverts or
bridges.Prior to the commencement of construction activities,
permit applications for stream crossing structures will be submitted
21
-_._-------,_.--~------------....--------_._----------
-!
..-
to the ADF&G as required by AS 16.05.870.Bridge crossings will be
preferentially utilized.Culverts will be designed in adherence to
the Drainage Structure and Waterway Design Guidelines (Harza-Ebasco
1985b)and the ADF&G velocity criteria to allow fish passage during
flood flows and cri t i call y low flows.For a spec i fi ed 1ength of
culvert,the water velocity criteria (Table 5)dictates the size of
culvert.
Drainage structures will be routinely maintained to ensure fish
passage.Accumu1 ated debri s at cu1 vert openi ngs wi 11 be removed.
Appropriate control measures will be undertaken as a part of routine
ma i ntenance to ensure that beaver dams do not interfere wi th fi sh
passage needs.
Construction activities will utilize water for gravel washing,fill
compaction and dust control.Water will be withdrawn from available
sources along the access corridor.Streams or lakes not supporting
fish will be utilized preferentially.Prior to water withdrawal,the
ADF&G and ADNR will be consulted for approval and permitting of
water removal sites.Water intakes will be screened as described in
the BMPM on Water Supply (APA 1985c).Water wi 11 be treated to
conform to ADEC/USEPA standards pri or to discharge.Water utili zed
for gravel washing will be channeled through settling ponds.
(b)Potential Impacts
Potential impacts on fisheries resources may result from alterations
in the physical characteristics of the aquatic habitat and/or direct
effects on aquatic organisms.Impacts identified for access road
construction and maintenance are presented in the anticipated order
of occurrence ·and consider both types of potential effects.The
drainages crossed by the access road are primarily clearwater
streams inhabited predominantly by Arctic grayling and Dolly Varden.
22
-
Table 5.Alaska Department of Fish and Game standards for passing Arctic
grayl~ng io be used on Susitna Hydroelectric Project stream
crosslngs •
Length of Culvert
(feet)
30
40
50
60
70
80
90
100
150
200
Average Cross-Section~l
Velocities at Outlet
(ft/sec)
4.6
4.5
4.0
3.6
3.3
3.0
2.8
2.5
1.8
1.8
.....
1 Each culvert must be installed so that at least 20 percent of the diameter
of each round culvert or at least 6 inches of the height of each
elliptical or arch type culvert are set below the streambed at both the
inlet and outlet of the culvert except when using bottomless arch
culverts or to avoid solid rock excavation.
2 Average cross-sectional velocities at the outlet of the culvert may not
exceed the velocities in the table except for a period not exceeding 48
hours during the mean annual flood.
Source:Edfelt 1981 and Title 5 Fish and Game Part 6 Protection of Fish and
Game Habitat Chapter 95 -Alaska Department of Fish and Game.
23
_______II'lI'i~"""''''''''------------------
-
-
-
(i)Clearfng
Potential impacts from the clearing phase of construction
include minor water quality degradations and some decrease in
aquat ic habi tat qual i ty at .stream cross i ngs.Water qual i ty
degradations .from increased erosion are likely to occur and may
include increased organic and sediment contributions to streams
(Fredrickson 1970,Brown and Krygier 1971,Megahan and Kidd
1972,and Cederholm et al.1980).The removal of cover
vegetation may increase water temperatures (Wasserman et al.
1984).However,degradations of fish and aquatic habitat will
be avoided by adherence to the following guidelines (APA
1985b):
Vegetated buffer zones will be retained at stream margins
until instre&m construction ;s necessary;
Cleared areas near streams and lakes will be stabilized to
prevent soil erosion into the water body;
Cleared material will be removed from water bodies to
prevent blockage of fish movements,deposition of organics
on substrates,and increased localized erosion;
Clearing of streamside vegetation will be minimized to
prevent loss of fish habitat,reduction in availability of
food organisms,and instream temperature variations;and
Stream banks will be promptly graded,mUlched,and
revegetated to minimize erosion.
These gUidelines will be utilized to avoid erosion related
aquatic impacts from turbidity and siltation increases in
nearby waterbodies.Increased turbidity from fine sediment
additions to streams generally reduces visibility and decreases
the ability of sight-feeding fish such as Arctic grayling and
24
~,
-
"....'
,~
"""'
-
(i i )
Dolly Varden to obtain food (Hynes 1966),thus effectively
reducing feeding habitat.Turbidity can reduce primary
product i on as 1i gilt penetration through the water column is
decreased (Lloyd 1985).
There is a considerable amo~nt of literature on the effects of
siltation on fish (Shaw and Magal 1943,Cordone and Kelly 1961,
Iwamoto et al.1978)and particularly on the effect on spawning
and incubation.A general conclusion reached by a review of
the literature (Dehoney and Mancini 1982)is that the greatest
adverse impact of siltation is on immobile eggs and on
relatively immobile larval fish.In general,siltation can
cause significant losses of incubating eggs and fry in redds,
predominantly by interfering wiIth oxygen exchange and waste
removal.Areas of groundwater upwelling flow would likely be
affected to a lesser extent than other areas because silt would
tend to be prevented from settl ing.However,since the BMPM
techniques (APA 1985b)will be followed,increases in suspended
sediments from clearing activ'ities are anticipated to be
minimal and temporary.
Cover removal at stream crossings may reduce fish habitat,
increase the exposure of fi sh to predators,increase stream
temperatures and lead to a decrease in fish populations (Joyce
et al.1980a).However,changes;from cover removal in the 44
ft (12.9 m)wide road corri dor are not expected to be great
enough to adversely affect fish and other aquatic organism
populations in the streams.Mit~gation beyond adherence to the
specified BMPM's (APA 1985b)is not likely to be necessary.
Stream Crossings
Impacts from stream crossings dur'ing new construction or during
road upgrading include the permanent loss of habitat,water
quality degradations,substrate alterations and potential
migration barriers.Some permanent loss of habitat will occur
25
.._-,------_.."""-_....._.----------_._-
....
-~
....
I
-
at the stream crossing site.Impacts on aquatic organisms from
water quality degradations and substrate alterations are
expected to be short in durat i on and will be avoi ded or
minimized through adherence to the BMP manual on Erosion and
Sedimentation Control (APA 1985b).Incorrectly designed or
constructed stream crossing installations may obstruct fish
passage.Potential migration barriers may occur if instream
activities coincide with spawning and overwintering migrations.
A permanent loss of habi tat wli 11 occur at the site of the
stream crossing structure.Impacts associated with the removal
of riparian vegetation at stream crossings are discussed in the
previous section on clearing.Fill embankments for culvert
i nsta11 at ions wi 11 dewater a sma 111 amount of habi tat.However,
the amount of habitat loss asso<:iated with stream crossing is
not expected to significantly affect stream populations.
During stream crossing construction,sediments will be released
into the stream.The impacts associated with increased
siltation and turbidity are desclribed in the previous section .
A review of the effects of sedimentation (Hall and McKay 1983)
found that the presence of sediment laden water can be expected
to reduce the stream's bio1og'ical productivity.Suspended
sediment levels are expected to revert to natural levels upon
cessation of instream activity.These short-term pulses of
increased suspended sediment at the anticipated levels are not
likely to significantly reduce tlhe productivity of the aquatic
ecosystem.Channel stabilization will proceed immediately to
shorten the duration of turbidity and suspended sediment
impacts as described in the BMPM (APA 1985b).Residual impacts
may include the short-term depos'ition of small amounts of silt
over spawni ng areas and benthi c production areas.Subsequent
high water events are expected to remove and di stri bute any
deposition.
26
._-------------------------------------------
....,
Equipment usage within streams m,ay contribute hydrocarbons and
degrade the water qual i ty.The E!qu i pment wi 11 be rna i nta i ned to
avoid fuel,hydraulic fluid or antifreeze leakages.Equipment
will be washed prior to the initiation of instream work to
remove grease buildup.Instream use of equipment will be
limited to the installation of stream crossin~structures.
Substrate alteration may occur during instream construction.
Sediments may be temporarily deposited downstream.The
substrate may be compacted when vehicl es cross the stream.
Permanent substrate alteration is expected at stream crossings
where cul verts are i nsta11 ed.On small systems,open bottom
arch culverts will be preferent'lally utilized to maintain the
natural substrate (APA 1985b).Natural stream substrate will
be placed over the ent ire bottom 1ength of culverts.The
amount of substrate alteration w'ill be limited and localized;
thus,damage to the aquatic resources is not expected to
require.mitigation.
Fi sh passage blockages may be created by stream divers ions
during construction.The evaluation species used in developing
passage criteria within the project area is Arctic grayling .
Although open-bottom arch culvelrts can be installed without
stream diversions,other culvert installation~will necessitate
stream di vers ions around the work area and back into the
natural stream channel until the crossing is completed.On
small systems,the stream may be flumed.Diversion or fluming
will reduce the amount of siltation downstream from the
construction area.Diversion will be accomplished in
accordance with ADF&G criteria (Table 6)and required fish
passage will be maintained.
Fish passage blockages may also be caused by the construction
of inadequate stream crossing structures.Crossings of streams
having documented fish or fish habitat at,or upstream from,
the construction site will be designed to pass fish.Figures 7
27
F""
I
Table 6.Alaska Department of Fish and Game Temporary Stream Diversion
Guidelines.
-
~
I
......
Temporary diversion channels in all streams
frequented by fish must be constructed and
controlled in the following manner:
(1)The width and depth of the temporary diversion channel must equal or
exceed 75 percent of the width and depth,respectively,of that portion
of the streambed which is covered by ordinary high water at the diversion
site,unless a lesser width or depth is specified by the department on
the permit for activities undertaken during periods of lower flow;
(2)During excavation or construction,the temporary diversion channel must
be isolated from water of the stream to be diverted by natural plugs
(unaltered streambank)left in place at the upstream and downstream ends
of the diversion channel;
(3)The diversion channel must be constructed so that the bed and banks will
not significantly erode at expected flows;
(4)Diversion of water flow into the temporiary diversion channel must be
conducted by first removing the downstream plug,then removing the
upstream plug,then closing the upstream end and the downstream end,
respectively,of the natural of the divertlad stream;
(5)Rediversion of flow into the natural stream must be conducted by removing
the downstream plug from the natural channel and then the upstream plug,
then closing the upstream and the downstl'eam end,respectively,of the
diversion channel;
(6)After use,the diversion channel and the natural stream must be
stabilized and rehabilitated as may be spec:ified by permit conditions.
Source:Edfelt 1981
28
o~~-.:~·-----------------
-
~,
....
o I
~
MILE
...
LEGEND
#-ADF&G STREAM NUMBER
rzJ EXISTING LAKES
_.,.-PROPOSED WAl"ANA ACCESS CORRIDOR
iIi ~~~~~~D~~~~6'~HABITAT NEAR THE
MATCH LINE FIGURE 10
SENSITIVE AQUA1·IC HABITAT AL.ONG THE NORTHERN
SECTION OF THE WATANA ACCESS CORRIDOR
Al.ASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:Sautner and Stratton 1984.Figure 7
29
ENTRI.X,INC.
HARZA·EBASCO
SUSITNA JOINT VENTURE
._,--~---------------------------------
-
and 8 illustrate the locations of sensitive fish habitat that
may be affected by construction of the Watana access road along
the planned ali gnment.Sri d~Jes wi 11 be i nsta,11 ed where
streamfl ows are 1arge.Bri dges are expected to be located at
stream crossings 5.8,12.0,13.7,and 27.5 miles from the
Denali Highway (Table 4).On smaller systems where fish
passage is required,open-bottom arch,multiple elliptical or
oversized circular culverts can be installed to maintain fish
passage (Joyce et al.1980a;Lauman 1976).Multipl ate
elliptical and oversized circulalr culvert inverts will be set
below the streambed elevation to a depth of at least one-fifth
their diameter to avoid perching and culvert outlets will be
armored to minimize erosion.Only at those stream crossing
sites without fish or fish habitat at,or upstream from,will
the design of the crossi ng be based sol ely on hydrol ogi c and
hydraulic criteria~The streams crossed at corridor miles
(eM's)10.7,11.7,18.0,23.0,23.7,24.8,28.5,37.2 and 37.8,
as measured from the Denal i High1,o1ay (Tabl e 4),do not appear to
have fish or fish habitat upstream from the crossing site
(Figures 7 and 8).
Arctic grayling and Dolly Vard,en spawning migrations to and
from overwintering areas cou"lld be impacted by instream
disturbances.Migrations by ev'aluation species occur during
several time periods throughout the year (Figure 5).Arctic
grayling likely migrate from lake or river overwintering
habitats,such as Deadman Lake,to spawning habitat in
tributaries following spring bre:akup.Spawning appears to end
in mi d June (McLeay et a 1.1983).Arct i c grayl i ng feed in
streams and lakes during the sumner prior to migrating to lakes
and rivers in the late fall for overwintering.Stream-resident
Dolly Varden predominantly feed during the summer months in
small headwater streams and are believed to remain in these
streams for spawning in late August to October.After
spawning,Dolly Varden are expE!cted to migrate to lakes or
deeper pools for overwintering.Instream activities during the
30
LEGEND#ADF&G srREAM NUMBERmEXlsrlNGLAKES
-PROPOSED DEVil CANYON ACCESS CORRIDOR
-PROPOSED WATANA ACCESS CORRIDOR
::::::::::;:;SENSITive AQUATIC HABITAT NEAR THE ACCESS
CORRIDOR
Q ,
~
MATCH LINE FIGURE 9
RIVER
sus/rNA
.....
-
SENSITIVE AQUATIC HABITAT ALONG THE CENTRAL
SECTION OF THE WATANA ACCESS CORRIDOR
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:Sautner and Stratton 1984.
Figure 8 ENTRIX,INC.HARZA-EBASCO
SUSITNA JOINT VENTURE
31
(iii)
spring and late fall could alter or block Dolly Varden
migrations (Figure 5).However,instream activities will be
scheduled to avoid the sensitive periods of Arctic grayling and
Dolly Varden migrations to minimize impacts to the fish
resources of the regi on.Figure 9 ill ustrates the sens it i ve
periods for streams crossed by the Watana access road.
Fill Placement
Potential impacts of fill placement on aquatic habitats include
habi tat loss through fill p1aCI~ment and increased suspended
sediment levels.The potential impacts will be minimized
through the proper construction techniques detailed in the BMPM
(APA 1985b).Residual impacts I)f fill placement are expected
to be negligible.
Fill utilized in stream crossin~J construction is not expected
to cover significant amounts of habitat previously used by
fi sh .The access road is ali 'gned outs i de the flood p1a in
except at the site of stream crossings.The impact on aquatic
habitat will therefore be minor.
Sheet flow blockages,resulting in ponding on one side of the
access road and drying on the other side,will be prevented.
Culverts and drainage structures will be installed under the
fill to maintain the integrity of the road and the water
drainage patterns which contribute to wetlands along Deadman
Creek..Some wetlands on stream margins provide rearing habitat
for juvenile fish.
Proper stabi 1i zat ion techni ques as outl i ned in the BMPM (APA
1985b)will be observed to minimize erosion and reduce
suspended sediment and turbidity contributions to waterbodies.
Fill with high organic and/or fines content will not be
utilized.Fills and cuts will be stabilized to prevent erosion
and revegetated as construction is completed.
32
1 .~.t1
~1 ))"1 )11 1 l'-1 1 1
STREAM Corridor Mile J F M A M J J A SON 0
ww
Unnamed Creek Nenana System 0.3
Tributarv to Lilv Creek 2.0 tI0 ~~
Lily Creek 3.0 ~@ ~
Seattle Creek 5.8 V/h ~I@ m ~
TributalV to Seattle Creek 7.7
Tributarv to Seattle Creek 8.7 ~~1m ~t«
Brushkana Creek 10.7
Tributary to Brushkana Creek 11.7 ~~
Brushkana Creek 12.0 '~~
Tributary to Brushkana Creek 13.7 ~~
TributalV to Brushkana Creek 16.9 00 ~~f0:I ~
Tributarv to Brushkana Creek 18.0
Deadman Creek 19.7 ~~
TributalV to Deadman Creek 23.0
TributalV to Deadman Creek 23.7
TributalV to Deadman Creek 24.8
TributalV to Deadman Creek 27.5 ~~~
TributalV to Deadman Creek 28.5 f0;V~~
TributalV to Deadman Creek 29.5 W ~~
TributalV to Deadman Creek 31.4
ltibutalV to Deadman Creek 36.9 Wh ~~~~
TributalV to Deadman Creek 37.2 f'l"~~
TirbutalV to Deadman Creek 37.8 f'l"~~
f77ZiI =Sensitive
rLLLLl Period
SENSITIVE PERIODS OF INSTREAM ACTIVITY,FOR
STREAMS CROSSED BY THE ACCESS CORRIDOR FROM
THE DENALI HIGHWAY TO THE WATANA DAM SITE ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 9
ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
(iv)Borrow Sites-Few impacts are anticipated from borrow excavations as the
construction techniques presented in the BMP manual on Erosion
and Sedimentation Control (APA 1985b)will be followed to avoid
sheet flow blockages and increased sediment and petroleum
contami nat ion.The majori ty of the fi 11 materi a1 for road
construction·will be obtained using side borrow techniques.
The remainder of the material will be excavated from small (10
to 20 acres)borrow sites located in well-drained upland areas
(Figure 10).Buffer zones will be maintained at stream margins
and the organic layers will be stockpiled for subsequent
rehabil i tat ion.If necessary,l~unoff control structures will
be ·installed.
Borrow excavations will adhere to the BMPM (APA 1985b)in order
to minimize sediment and petroleum product contributions to
waterbodies.Buffer zones will be maintained at stream
margins.Runoff control structUl"es will be installed at borrow
sites and turbid water will be channeled through stilling ponds
prior to discharge in adherence to BMPM gUidelines (APA 1985b).
Flocculants will be used,if necessary,to settle fine sedi-
ments.Discharged water will conform to water qual ity stan-
dards of the ADEC (18 MC 70)and the USEPA.Erosion will also
be minimized by excavating matE!rial according to'the gravel
removal guidelines of the USFWS (Joyce et al.1980b).Residual
impacts are discussed in greater detail in Section 3.1.1.
(v)Disposal Sites
Water quality degradations may result from surface water runoff
originating at disposal sites.Sediments and organics may be
washed into streams and lakes.However,the disposal sites
will be located and configured (Section 3.1.1(b»to avoid
material introduction during high streamflows or rainfall
events.
-34
..__..,----------------------------
Il
®
1~l],1I
WATANA D::~T:I'
SITE A
-1I
)
6
--J
LOEVIL CANYON
RESERVOIR
o I •-.IS
SCALE
LEGEND
c::a 8ORROW1QUAJIIIY SITE UIlITS
w
U1
,1 )..~t ~I j
I
0 •.....LOCATION "AP
'lC"LI
PLAN VIEW OF POTENTIAL WATANA BORROW SITES ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:APA 1985h.Figure 10 ENTRIX,INC.
HARZA-EBASCO
SUS/TNA JOINT VENTURE
-i
....
-
-
.-
(vi)
(vii)
Water Removal
Potent i al impacts from water remloval incl ude fi sh entrai nment,
habitat dewatering and increases in suspended sediment levels.
Adherence to the BMPM guidelines for Water Supply (APA 1985c)
and the ADF&G water removal criteri a wi 11 avoid or minimize
these impacts.
Water removal along the access corridor will preferentially
utilize shallow lakes without fish such as the lakes located at
13 and 40 mi 1es (21 and 64 km)from the Denal i Highway.In
streams,no more than 20 percent of the instantaneous flow will
be removed at any time,as sugges;ted by the ADF&G water removal
gUidel ines.The ADNR permits for water removal will assure
comp 1 i ance wi th approved water removal pract ices .All water
intakes will be screened and si:zed according to ADF&G intake
des i gn cri teri a to prevent fi sh entrapment,entrainment,and
impingement (APA 1985c).
\
The ADF&G criteria state that:(1)all intakes should be
screened;(2)openings in the sClreen should not exceed 0.04 sq
in;and (3)water velocity at the screen should not exceed 0.1
ft/sec (0.03 m/sec)in anadromolls fish streams or 0.5 ft/sec
(.15 m/s)in non-anadromous fish supporting streams or lakes.
Operation and Maintenance Activities
During road construction and operation,safe practices will
avoid accidents invol ving transport vehi cl es,incl udi ng those
carrying petroleum products,to the greatest extent possible.
The access road will be designed without hazardous curves and
hills.Traffic control signs and guardrails will be installed
where needed.Dust will be controlled in summer,snow will be
plowed and ice will be sanded in winter .
36
-,
-
-
An Oil Spi 11 Contingency Pl an wiill be developed pri or to the
beginning of construction activities in accordance with the BMP
manual on Oil Spi 11 Conti ngellcy Pl anni ng (APA 1985f)to
minimize water quality impacts should a spill occur.The plan
will recognize site specific problems such as the difficulty in
recovering hydrocarbon contamina,tion in rivers under freezing
conditions.Residual impacts from an accidental fuel spill may
cause short-term reductions in water quality within the
watershed as petroleum products are likely to enter the water.
An acci dental spill,if located adjacent to fi sh habitat,woul d
1i kely injure or ki 11 fi sh di re1ctly impacted by the petrol eum
products.Aromatics in gasol i ne or di esel fuel are
particularly toxic until evaporated.The heavier hydrocarbon
fractions can coat streambeds and interfere with the production
of aquatic food organisms consumed by fish (Kolpak et al.
1973).Following a major spill,an assessment of the aquatic
losses woul d be conducted by the Envi ronmenta1 Fi e1d Offi cer
(EFO)described in Section 2.2,,2.Appropriate site-specific
mitigative measures would be negotiated in consultation with
the resource management agencies.
The BMP manual on Fuel and Hazardous Materi al s (APA 1985e)
provides gUidelines to prevent petroleum products from
contaminating water in the area during refueling or storage.
Activities associated with petroleum storage or transfer will
only be allowed in bermed areas.Spillage will be transported
by 1oca1 runoff to a collect i 0111 area and treated pri or to
release into water bodies.
The access road will be properly maintained so that road
operation impacts on aquatic habitats will be minor.If gravel
is displaced during road operation or maintenance activities
into wetlands,it will be removed.Maintenance will include
removal of culvert and bridge debris to maintain fish passage.
37
..-
-
".,..
.....
The greatest 1ong term source of adverse impacts upon fi sh
populations is likely to be increased fishing pressure
resulting from improved access to streams and lakes.As stated
in Section 2.1.1(a),the Watana access road will cross
Brushkana,Lily,Seattle,and Deadman creeks as well as other
small,unnamed streams.These c'I earwater streams are i nhabi ted
by populations of Arctic grayling and Dolly Varden which are
thought to be at their maximum level (ADF&G 1981).Deadman
Creek,in particular,is known for its abundant population of
large Arctic grayling.The reach of Deadman Creek between the
fall s and Deadman Lake is cons i de red pri me Arctic grayl"j ng
habitat.Studies to date have indicated a relatively high
percentage of "older"age group fish (up to 9 years)(Sautner
and Stratton 1984).By subjecting thi s stream to increased
fishing pressure,many of the larger,older fish will be
removed from the popul at ion,a'i teri ng the age structure and
possibly reducing reproductive potential (Schmidt and Stratton
1984).A similar impact may occur in other grayling streams.
During road construction,several thousand workers will be in
the area between the Denal i H'ighway and the Watana damsite
(Section 3.1.1(a».A survey of construction workers on the
Terror Lake Hydroelectric Proje<:t indicates that workers lack
sufficient leisure time to participate frequently in
recreational activities such as fi shing (Harza-Ebasco 1985c).
During construction at Terror Lake from 1983 to 1984,57
percent of the project personn,el had not fi shed wi th in ten
miles of the project site."rwenty-three percent reported
fishing less than 10 times and B percent had fished more than
25 times.Ten percent of the project personnel did not respond
to the survey evaluating recreational usage of areas near the
project site.
However,access w"ill be open,ed to the publ ic following
completion of the Stage III construction of the Susitna dams.
Although this area has been a recreational area in past years,
38
it has not experienced a large influx of people.Unless
contro11 ed,thi s i nfl ux wi 11 i nc:rease fi sh i ng pressure on the
streams and lakes in the area.The effects of such an increase
in pressure were modeled by Sch~J1idt and Stratton (1984).The
finding was that the trophy-s'ized Arctic grayling presently in
the creek could only be maintained if a catch-and-release
policy was implemented.Allowing a harvest would lead to a
population dominated by smaller fish.Alternative management
po 1i ci es may be the only method to 1essen these effects of
increased pressure.These policies are the jurisdiction of the
Alaska State Board of Fisheries (AS 16.05.251);however,APA
will provide the Board with project information needed to
formulate policy decisions.
2.1.2 -Watana to Devil Canyon
(a)Description
:rhe pl anned Stage II Devil Canyon access road will depart from the
Watana main access road at mile 38.5 and will traverse high tundra
throughout most of its length.Dense shrub vegetation and trees are
encountered downstream of,Devil Canyon as the access road approaches
the Susitna River crossing (RM 150).The Susitna River will be
crossed by a high level suspension br'idge with an ov~rall length of
1,790 ft (550 m)to link the rail spur from Gold Creek to the
construction camps (APA 1985g).Bridges are expected to be
installed at streams located 2.2,8.0,15.7 and 22.4 miles from the
junction with the Watana access road (Table 7).The terrain has
gentle to moderate slopes allowing road construction without deep
cuts except in the case of several stream crossings.Construction
will begin and is expected to finish 'in 1995 as shown in Figure II.
Access construction and maintenance ....,ill be conducted in the same
manner as the Watana access road (Section 2.1.1{a».
The Devil Canyon access road will cross
tributaries to the Susitna River (Figure 4).
39
numerous clearwater
Tsusena Creek will be
Table 7.Streams to be crossed by the Devil Canyon access road and
railroad spur from Gold Creek.
Habitat
Stream Miles From Species Present Condition it
.-(ADF&G Survey No.)Watana Road at Crossing Crossing
Tsusena Cr.(23)2.2 Dolly Varden,1
sculpin
Trib.to Swimming 8.0 Dolly Varden,3
Bear Cr.(24)sicul pi n
Trib.to Swimming 8.7 probably none 5
Bear Cr.(25)
Trib.to Swimming 11.1 (Dolly V~rden,5
Bear Cr.(26)siculpin)
Trib.to Swimming 11.4 (Dolly V~rden,5
Bear Cr.(27)s,culpin)
Trib.to Swimming 12.0 Drolly Varden,3
Bear Cr.(28)sculpin
Trib.to Swimming 12.4 Dolly Varden,3
Bear Cr.(29)s'culpin
Trib.to Swimming 13.9 p'robab 1y none 5
Bear Cr.(30)
pll:l,Trib.to Swimming 15.7 Dolly Varden,2
Bear Cr.(31)slcul pi n
Trib.to Devil 18.9 Dlolly Varden,1
.~Cr.(32)slcul pin
Trib.to Devil 22.2 slculpin 3
Cr.(33)
Devil Creek (34)22.4 sculpin 3 (because
of fish barrier)
Trib.to Devil 24.3 Dolly Varden,3
Cr.(35)sculpin
Trib.to Devil 24.5 Dolly Varden 3
Cr.(36)
40
-
-
Table 7 ,(continued)
Stream
(AOF&G Survey No.)
Trib.to Devil Cr.
Susitna Ri ver
Jack Long Cr.
Encroachment
Trib.to Jack
Long Cr.(37)
Trib.to Jack
Long Cr.(38)
Trib.to Jack
Long Cr.(39)
Unnamed Creek (40)
Unnamed Creek (41),
(Waterfall Cr.)
Gold Creek (42)
Miles From
Watana Road
26.3
35.1
36.3-39.3
37.3
38.9
39.9
43.3
44.5
47.9
Species Present
at Crossing
([)olly Varden)2
g)'ayl ing,Dolly
Vclrden,scul pin,
whitefish,burbot,
sucker,chinook,
coho,pink and
chum salmon.
chinook,coho,
chum and pi nk
sellmon,rainbow
b'out,grayling,
sc:ul pi n
sc:ul pi n
(chinook,coho)2
(sculpin)2
chinook salmon,
sculpin
Al'ct ic grayl ing,
chinook salmon,
sculpin
chinook,coho,
plink salmon
Habitat
Condition ft
Crossing
3
4
4
4
2
4 (because
of fish barrier)
1
2
3
1
"...,
.-
1 =excellent,2 =good,3 =1imited,4 =marginal,5 =poor
Ratings deduced from information presented in Sautner and Stratton (1984).
(species)can be reasonably expected,but not verified
---=not evaluated
Biological Data Source:Sautner and Stratton 1984
41
---------"""""f"'T-,--------------',....-----------------
1 I ),I J 'I 1 )]1 )-~--l 0_01 I
~
N
OEICI.'TIO_11111 II"1"7 ....1 •••2000 2001 2002 200;2004 2001 2001
01 01
02 ..AIN ACCESS 02
03 03
-..0404SiTEFACIliTIES
05 IVE"SION PLU 05
06 DIVERSION TUNNELS ..........---06
07 J.DIV~t1~IU"I 07
0$COFFERDA"S -,.............................,\.,0$
09 09
10 MAIN DAM --"_'1"111111'''-'0
11 II
12 SADDLE DA"_NII_._"'h,"l1t1 ,....,',....,''''~,............"",..12
13 '3,.OUTLET FACIliTIES 1I.'.'.'.'.l.••••••••••e '4
'5 .5
16 SPillWAY 111Hl1I11'''''IIIII'''''_III"U,,""!:"":!,!J!!'::r:!""11'"•.•.•.•....,.,.16
,7 11
18 '8
•9 I •
20 POWER INTAKE 1iI1___........''iiili .,.'.i.........20
2'21
22 POWER TUNNELS --22 -
23 ACCESS VULT 23
24 POWERHOUSE ._U.......-..-M -,...24
25 25
26 TRANSFOR..ER GALLERY/CA8LE SHAFTS 1--_•...-_.........26
27 I 27
28 TAILRACE/SURGE CHA..8ER -......_.."'..MMMIJHltlHtlt II II 28
29 2.
30 TURBINES/GENERATORS ...................1.'..............,•••'e'e 30
31 PH "R4N"S 31
32 MECHJELECT.SYSTE..S ,.,.,.,.,,.•,..•.•I.'............,l.i8i8,8,32
33 ~TR 33
34 SWITCHYARD/CONTROL 8LDG.--.....,......,,""..,..........34
35 35
36 TRANS,,'SSION liNES ~•.,•••1.,••8.!~"
37 1 EL.1455 37
3$IMPOUNDMENT 3$
3"UNITS ,-I 2 3 4 1""""""3.
40 TEST &CO....,SSION ....8'8'"'',••,40
41 4'
42 42
43 43
.-44
UOE_D
-ACCESS/FACILITIES
_EXCAVATlO~/FOUNOATION TREATWENT
.,,,.........,,f-ILL
-CONCRETE
__.__MECHANICAL/ELECTRICAL
.....IMPOUNOMENT
SCHEDULE FOR THE CONSTRUCTION OF THE STAGE n ALASKA POWER AUTHORITY
DEVIL CANYON DAM AND RELATED FACILITIES SUStTNA HYDROELECTRIC PROJECT
ENTRIX,INC.HARZA-EBASCO
Reference:APA 1985i.Figure 11 SUSITNA JOI NT VENTURE
.-
""'"
-
crossed 2.2 mil es (3.5 km)from the!Watana access road junction.
Although this creek appears to contain excellent fish habitat in the
vicinity of the access road crossinig,only small stream resident
Dolly Varden and sculpin were located within this reach (Sautner and
Stratton 1984).Arctic grayling utilize the mouth of Tsusena Creek
(ADF&G 1981,1983).However,a waterfall downstream of the access
road crossing and approximately 3 miles (5 km)from the tributary
mouth may have prevented the estalb1i shment of Arct ic grayl i ng
popul ations upstream of thi s fi sh barrier (Sautner and Stratton
1984).
The access road is sited in the Swimming Bear Creek drainage.Eight
small,high grad i ent tri butari es to Swi mmi ng Bear Creek will be
crossed.Several of these streams sUlpport Dolly Varden and sculpin
(Sautner and Stratton 1984).The road will parallel Swimming Bear
Creek for approximately 6 miles (10 ~n).
Withi n the Devil Creek drai nage,the access road wi 11 approach
Swimming Bear Lake and will cross Dlevil Creek and several of its
tributaries.The road will approach within 1300 ft (400 m)of
Swimming Bear Lake,which supports a population of Dolly Varden
(Sautner and Stratton 1984).The tributary to Devil Creek draining
from Swimming Bear Lake will be crossed.This tributary is used
extensively by Dolly Varden for spawn-jng and rearing during the open
water season (Sautner and Stratton 1984).The access road wi 11
parallel Devil Creek for 5 miles (8 km)and encroach on the Devil
Creek floodplain for almost 1 mile (1.6 km).Devil Creek will be
crossed 22.4 miles (36 km)from the Watana access road junction.
Devil Creek and its tributaries support Dolly Varden and sculpin
(Sautner and Stratton 1984).
The access corridor will approach a series of lakes between Devil
Creek and the Susitna River.The High Lake Complex,approximately
28 miles (45 km)from the Watana junction,contains rainbow trout,
Dolly Varden,and sculpin (Sautner and Stratton 1984).
43
~~~_D --------------
Pink,chinook,coho,chum,and soclkeye salmon,Arctic grayling,
Dolly Varden,round whitefish,burbot,longnose sucker,and sculpin
may occasionally utilize the aquatic habitat in the vicinity of the
Susitna River crossing.However,the habitat is considered to be
poor relative to the alternative habitat available upstream and
downstream.Table 7 lists the streams to be crossed by the Devil
Canyon access road and the fish specil!s that are expected to inhabit
these streams.Figures 12 and 13 illustrate the sensitive aquatic
habitat encountered by the Devil Canyon access road corridor.
(b)Potential Imoacts
Potential impacts identified for the Denali Highway to Watana access
road (Section 2.1.1)are also applicable to the Devil Canyon access
road.Additional impacts are discussEld further.-
(i)Clearing
The Devil Canyon access corridor will encounter dense brush and
trees and will require more vegetation clearing with chainsaws
and hydro-axes than the Watana access corridor.Simil ar
measures will be undertaken to prevent aquatic impacts from
increased erosio~.A need for additional mitigation is not
anticipated if clearing proceeds according to the BMPM
~
techniques (APA 1985b).
(ii)Stream Crossings and Encroachments
,~
All construction will adhere to the BMPM techniques (APA 1985b)
to avoid or minimize aquatic impacts from access road stream
cross i ngs and encroachments.Surface runoff along the Devil
Canyon access road encroachment on the Devil Creek fl oodpl a in
wi 11 be drained through cul verts des i gned to rna i nta in surface
water contributions to wetland habitat (Harza-Ebasco 1985b).
Additional impacts are not expected due to the encroachment.
44
1
,J J J 1 J 1 )J 1 i
LEGEND
~
~:r
r-
Zm
:!!
~l·~I:,
I
I
\
.-A )Lonp V .'Lskfl'/JlJ/
~n,I:Round
tf/)~Lskflj
-!
q<1D
IP
AOF&G STREAIoI NUMBER
EXlSTING lAKES
PROPOSEO OEVIL C\NVON ACCESS CORRIOOR
PROPOseD WAlANA ACCESS CORRIOOR
SENSITIVE AQUATIC HABITAT NEAR THE ACCESS CORRIOOR
o I
l ,
1IIl.f
'::::::'.':'.
#
...J2L
SENSITIVE AQUATIC HABITAT ALONG THE WATANA AND
DEVIL CANYON ACCESS CORRIDORS ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:Sautner and Stratton 1984.
Figure 12 ENTRIX,INC.
HARZA-EBASCO
SUS I T NA JO I NT VE N T U R E
l"
o I
L...---...I
MILE
;:
~::c
r-
Zm
Jl
!j)
C
:IIm
~
"£GEN~
++-GOLD CREEK RAILROAD CORRIDOR*"ADF&G STREAM NUMBERmEXISTINGLAKES
PROPOSED DEVIL CANYON ACCESS CORRIDOR
- •-ANCHORAGE -FAIRBANKS INTERTIE
::::;:;::::;::::.SENSITIVE AOUATIC HABITAT NEAR THE ACCESS CORRIDOR
J
,.J::.
0'1
SENSITIVE AQUATIC HABITAT ALONG THE WESTERN
SECTION OF THE DEVIL CANYON ACCESS CORRIDOR
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:Sautner and Stratton 1984.Figure 13
ENTRIX,INC.HARZA·EBASCO
SUSITNA JOINT VENTURE
-
(i i i)
The access road will cross the Devil Creek tri butary drai ni ng
from Swimming Bear Lake.This tributary provides the only
documented spawning and rearing habitat for the lake population
of relatively large Dolly Varden l ,up to 375 mm in length,which
are bel i eved to overwi nter in S\lIi romi ng Bear Lake (Sautner and
Stratton 1984).Instream actjivities during the fall may
disturb Dolly Varden spawning and impact the lake population.
The deposition of silt,due to instream activities,onto gravel
containing embryos could reduce embryo survival with a
subsequent reduction in year class strength.Instream
activities will be scheduled to avoid sensitive periods for
streams supporti ng Arctic grayl i ng and/or Dolly Varden as shown
in Figure 14.
Fi 11 Pl acement
Fill placement in the Devil Cref~k floodplain will follow BMPM
techniques (APA 1985b)to prevent draining wetlands.
Revegetation will proceed as fill is stabilized.Residual
impacts are expected to be neg1i9ible.
(iv)Borrow Sites
Fill for the Devil Canyon access road will be obtained
predominantly through side borrow techniques;the potential
impacts are described in Section 2.1.1(b).
(v)Operation and Maintenance Activities
Increased fishing pressure on lakes and streams in the vicinity
of the access road is expected to be the greatest long term
adverse impact on the fi sheri es resources.Swi mmi ng Bear and
'F""Devil creeks contain numerous Arc:tic grayling and Dolly Varden.
The High Lake complex also c:ontains rainbow trout.The
population composition is expected to be altered by the
47
---~-------------------,---_._-----------------
t 1 )..--1 -)._-]J
STREAM Corridor Mile J F M AM J J AS 0 NO
,p.
co
Tsusena Creek 2.2 V//J ~~~r/"~~
Tributary to Swimming Bear Creek 8.0 I/~V~~
Tributary to Swimming Bear Creek 8.7
Tributary to Swimming Bear Creek 11.1 I
Tributary to SWimming Bear Creek 11.4
Tributary to Swimming Bear Creek 12.0
Tributary to Swimming Bear Creek 12.4
Tributary to Swimming Bear Creek 13.9
Tributary to SWimmina Bear Creek 15.7 ~~V/h ~
Tributary to Devil Creek 18.9 ~~V~~
Tributary to Devil Creek 22.2
Devil Creek 22.4
Tributary to Devil Creek 24.3 V/h /"//1 ~
Tributary to Devil Creek 24.5 /"/h /"/h ~
Tributary to Devil Creek 26.3
Susitna River 35.1
Jack long Creek Encroachment 36.3-39.3 I//h V'l ~~V~~.
Tributary to Jack LonaCreek 37.3
Tributary to Jack lona Creek 38.9
Tributary to Jack lona Creek 43.3
Unnamed Creek 43.3 JI//1 Jjt V~~/~0
Unnamed Creek ("Waterfall Creek")44.5 /7fi ~
Gold Creek 47.9 W,ij '/h V/~V;!/~0
I7777:it :Sensitive
lLLLLA Period
SENSITIVE PERIODS OF INSTREAM ACTIVITY FOR
STREAMS CROSSED BY THE ACCESS AND TRANSMISSION
LINE CORRIDORS TO THE DEVIL CANYON DAM SITE
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 14 ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
reduction or elimination of older-age classes (Sautner and
Stratton 1984).
2.1.3 -Secondary Roads
(a).Description
The secondary roads are anti ci pated to be short in 1ength and not
require stream crossings.Short spur roads will be.needed to reach
the material borrow and disposal sites which are not located
adjacent to the access corridors.Access to and within the
construction camps and villages will also require the construction
of secondary roads.The probable locations and alignments of these
auxiliary access roads which will be constructed principally during
Stages I and II are illustrated in Figures 15 and 16.
(b)Potential Impacts
Potential impacts on aquatic habitats from the construction,
operation and maintenance of the secondary roads are not expected to
be significant as stream crossings or encroachments are not
expected.The BMPM techniques (APA 1985b)will be applied to avoid
or minimize potential aquatic impacts.Erosional and clearing
impacts identified for the Watana access road (Section 2.1.1(a)are
relevant for secondary roads.
:2.1.4 Ra;1road from Go 1d Cree k to Dev il Can yon
(a)Description
A railroad spur of the Alaska Railroad is planned from Gold Creek to
Devil Canyon for Stage II development.The railroad construction is
scheduled to begin in 1995 and is estimated to be completed in 18 to
24 months (Figure 11).
49
Jj11J1J1J
..,"\..
.-:~'\..
't'\'~,.
.~~~1!//
//)
u;;;j~(I
i}/
r/!0-::::r
\\l~?!/~..~"\~.,.;rJ.f'.~
_..1/
y-~
f
.----.-¥--,,',4 PiiEK
ii'.~~II
FILTE~'I'SOURCE IIGG~EGATE .-JI_...._"'/~.,.~-.~".
/•._•.~_..•_..~USlTNA c:':::>.....~/O-..·_~-'--0:-:::..~IVE~"-'.----.•~.-~..........._.....--......---/
DOWNSTREAM //'~--~.J~'~~
1
LEGEND
MAIN ACCESS ROAD
HAULROAO
WASTEWATER OUTFALL
STAGE III NORMAL MAXIMUM
AESERIIDIA lEVEL
STAGE I NORMAL MINIMUM
RESER'wOIA LEVEL
1
@
U1
o
,--
PLAN VIEW OF THE WATANA DAM,COFFER DAMS,
RELATED FACILITIES AND DISPOSAL AREAS
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:APA 1985j.Figure 15 ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
J --1 -])1 )---1 !
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
LEGEND
-_••••_-HAUL ROAD
••••••••••••NORMAL MAXIMUM
RESERVOIR lEVEL
\
\\,\
\''''.~-:;;=-;;;-;:-::;:-;
~\~
~-._~J
U1 I ""-·.SUSlTNA·ii::'~
I-''\LEVl;J...PRIDGE
-'500--.........
PLAN VIEW OF THE DEVIL CANYON DAM,COFFER DAMS
AND DISPOSAL AREAS
l'~
i<>0,,'-.
SCALE
-'.
@
1000 looa ....,
~
Reference:APA 1985j.Figure 16 ENTRIX,INC.HARZA-EBASCO
SUSITNA JOINT VENTURE
,-,
The railroad access corridor will depart from the eXisting railroad
at Gold Creek and proceed north and east to the construction camp-
site.It will remain on the south side of the Susitna River.The
railroad will cross Gold Creek,which contains excellent fish
habitat (Sautner and Stratton 1984)and is known to support small
numbers of pink and chinook salmon (ADF&G 1981,1983;Barrett et al.
1984).Several tributaries that enter the Susitna River between
Gold Creek and Jack Long Creek will be crossed;the tributaries
contain Arctic grayling,chinook salmon,and sculpin (Sautner and
Stratton 1984)(Table 7).Some of these tributaries are important
sources of clear water for sloughs,which provide spawning area for
salmon.The access corridor closely parallels Slough 20 and Slough
21 which are utilized by adult pink,chum and chinook salmon (ADF&G
1981,,1983;Barrett et al.1984).The railroad will parallel Jack
Long Creek for approxi mate 1y 3 mil es (5 km).The railroad wi 11 be
located within the floodplain and cross three tributaries of Jack
Long Creek.Jack Long Creek contains small numbers of pink,coho,
chinook,and chum salmon,rainbow trout,Arctic grayling and sculpin
(ADF&G 1981,1983;Barrett et al.1984;Sautner and Stratton 1984).
One of the tri butari es appears to be access i bl e to fi sh and may be
utilized by adult or juvenile salmon (Sautner and Stratton 1984).
The railroad terminus and turnaround at Devil Canyon will be located
adjacent to the upper reaches of Jack Long Creek.Bridges will be
constructed where the railroad crosses tri butari es to Jack Long
Creek.
(b)Potential Impacts
Potential impacts resulting from the railroad access construction,
operation and maintenance will be similar to those impacts
i dent i fi ed for the Watana access road (Sect ion 2.1.1 (b».
Additional site specific impacts are discussed further.
(i)Clearing
Construction of the railroad access corridor will require
extensive hardwood tree clearing.BMPM clearing techniques
52
(APA 1985b)will be utiliz~d to avoid or minimize impacts on
the aquatic resources from turbidity and siltation increases.
Materi a1 wi 11 be removed from streams to prevent fi sh
blockages.
(ii)Stream Crossings or Encroachment
Bridges and culverts will be installed according to BMPM
guidelines (APA 1985b)to maintain fish passage and to prevent
turbidity and sedimentati on impacts on sloughs and cl earwater
streams.Streams with large amounts of flow,such as Gold
Creek,will require bridges.Encroachments into floodplains
will occur along Slough 20 and Jack Long Creek.As described
in Section 2.1.1(b),culverts will be installed to continue
surface runoff contributions to wetlands.
Instream activity during summer and fall may cause salmon to
avoid spawning habitat in Gold and Jack Long creeks.Instream
activities will predominantly be restricted to early or
midsummer to avoid resident and anadromous spawning periods
(Figure 14)as explained in Section 2.1.1(b).
-
(i i i)Fi 11 Pl acement
The BMPM (APA 1985b)techniques will be utilized to avoid
detrimental impacts on the aquatic resources associ ated with
fi 11 pl acement near sloughs and strea~s.Along Slough 20 and
Jack Long Creek,fill will be stabilized to prevent sediment
i nf1 ux to the cl ear water.Temporary increases in suspended
sed"iments may impact sight feeding fish,such as Arctic
grayling.However,Arctic grayling successfully migrate
through the turbid mainstem during summer months (ADF&G 1983).
Residual impacts from fill placement are expected to be
negligible so long as suspended sediment increases are short in
duration.
53
.-
(iv)Borrow Sites
Borrow material for railroad fill will be obtained from Borrow
Site G.Borrow Site G will be extensively used for the Devil
Canyon dam construction and wi 11 be located at the confl uence
of Cheechako Creek and the Susitna River upstream of the Devil
Canyon dam site (Figure 17).Gravel removal is expected to be
confined to the channel margins.The USFWS Gravel Removal
Guidelines (Joyce et al.1980b)and the BMP Manual on Erosion
and Sedimentation Control (APA 1985b)will be applied to
excavation activities.Buffers will isolate the excavation
from Cheechako Creek and the Susitna River.Aggregate washing
water will be channeled through settl ing ponds and reused.As
the borrow site will be permanently i nunda ted by the Devi 1
Canyon reservoir,rehabilitation will not be necessary.
Impacts from Borrow Site G are discussed in greater detail in
Section 3.1.2(a).Incremental impacts from excavations for
railroad access construction will be negligible.
(v)Operation and Maintenance Activities
The railroad access corridor may allow increased fishing
p·ressure on southside streams and sloughs between Gol d Creek
and Devil Canyon.The populations in these streams are small,
however,and are not expected to attract significant pressure.
2.2 -Access Mitigation
.;;;;.Mitigation of potential impacts during construction of the access roads and
the railroad will be achieved primarily by adherence to the BMPM construction
techniques (APA 1985b).Erosion will be minimized·by utilizing proper
clearing and soil stabilization procedures as outlined in the BMPM on Erosion
and Sedimentation Control (APA 1985b).Revegetation will be scheduled to
proce '2d in segments immediately after portions of the roads or railroad are
completed.streams will be crossed following BMPM gUidelines (APA 1985b)in
order to minimize impacts.Scheduling of construction activities is another
54
,-----"---~~~,SOO~\)-------.~/----......J.~--..~'--,
--......~1500.·~
]J
1000 2000 F£I[T
~SCALE
LEGEND·
---BORROW/QUARRY SITE LIMITSC":>
11~)
~
-1
~-'500
r
(JI
(JI
PLAN VIEW OF POTENTIAL DEVIL CANYON BORROW SITE
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 17
Reference:APA 19B5h.
ENTRIX,INC.HARZA-EBASCO
SUSITNA JOINT VENTURE
,~
--
means of mitigation that would avoid or minimize adverse impacts to fish and
aquatic habitats.Movements of vehicles through streams during periods of
peak Arctic grayling and Dolly Varden migration will be avoided.Figure 5
i 11 ustrates these mi grat i on peri ods. Instream and streambank construct ion
will be minimized at streams containing sensitive habitat during peak
migration periods to allow successful passage of the majority of the
population to spawning or overwintering habitat.Figures 9 and 14 present the
sensitive periods for the streams crossed by the access corridors.
Potential impacts were identified in Section 2.1;Section 2.2.1 discusses
these impact mechanisms and the mitigation measures that will be applied
during and after access construction.Those sources of impact considered to
have greatest potent ia1 for adverse effects to the aquat ic envi ronment are
given highest priority.Measures to aVOid,minimize,rectify and reduce
impacts are discussed.Continued monitoring of the construction facilities
and activities will ensure that impacts to the aquatic environment are avoided
or minimized.Monitoring (Section 2.2.2)can identify areas that may need
rf'"rehabil itat i on or increased maintenance efforts and areas where previ ous
mitigation measures are inadequate and remedial action must be taken.Costs
associated with all phases of maintenance and monitoring are outlined in
Table 8.
2.2.1 Impact Mechanisms and Mitigation Measures
(a)Increased Fishing Pressure
(i)Impact Mechanism
The sport fishing pressure on the local streams and lakes will
substantially increase.The access roads will allow fishermen
to reach areas that previously received limited use.
(ii)Mitigation
During the construction phase,access to the streams will be
I"'"limited by closing roads to unauthorized project personnel and
56
Table 8.Estimated cost for water quality and fisheries monitoring (in 1985
dollars)during construction (1990 to 2012)
-
Year
199011
1991 11
1992 11
1993~/
199411
1995~l
19964.1
19974.1
1998.2.1
1999.2.1
1200.2.1
1201.2/1202~/
12031/1204~/1205~/1206~/1207~/1208~/1209~/
1210
2011
2012
Management
280,000
280,000
280,000
420,000
280,000
280,000
420,000
420,000
280,000
140,000
140,000
140,000
140,000
280,000
140,000
140,000
140,000
140,000
140,000
140,000
140,000
140,000
140,000
Fi eld Labor
400,000
400,000
400,000
600,000
400,000
400,000
600,000
600,000
400,000
200,000
200,000
200,000
200,000
400,000
200,000
200,000
200,000
200,000
200,000
200,000
200,000
200,000
200,000
Field
Equipment
25,000
30,000
15,000
25,000
10,000
10,000
15,000
15,000
10,000
5,000
5,000
5,000
5,000
10,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
Travel
10,000
10,000
10,000
15,000
10,000
10,000
15,000
15,000
10,000
5,000
5,000
5,000
5,000
10,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
Total
(x1000)
715.0
720.0
705.0
1,060.0
700.0
700.0
1,050.0
1,050.0
700.0
350.0
350.0
350.0
350.0
700.0
350.0
350.0
350.0
350.0
350.0
350.0
350.0
350.0
350.0
TOTAL
AVERAGE ANNUAL
12,650.0
550,000
11Y Inlcludes Stage I.1Jccess,facilities,Watana Dam,and transmission line11Includesallof,plus Stage II access .
!/Inlel udes Stage I~atana Dam,pl us Stage II access
.5/Inl:ludes all of ,plus Stage II Devil Canyon Dam
Includes Stage II access and Devil Canyon Dam~Includes Stage 16 Devil Canyon Dam~Includes all of 2/,plus Stage III Watana Dam
Includes Stage III Watana Dam
Reference:APA 1985g
57
-
(b)
(i)
the general public.The Alaska Board of Fisheries will be
provided information needed to develop management policies.
Some watersheds,such as the Deadman Creek/Deadman Lake system,
are expected to require special management considerations if
current stocks are to be maintained (Schmidt and Stratton
1984).These regulations may take the form of reduced seasons
or catch limits,imposition of maximum or slot size limits,or
control of fishing methods.Since public health regulations
will not allow sport-caught fish to be stored or prepared at
public food service facilities,the project policy will be that
all fishing done by project personnel and contractors be
restricted to catch-and-release.
Stream Crossings and Encroachments
Impact Mechanism
(i i )
During construction,fish are likely to avoid
by equipment operated in or near streams.
overwintering migrations may be interrupted.
Mitigation
areas di sturbed
Spawning and
-
-
\~-
Construction activities in streams supporting fish populations
will be scheduled,if possible,to avoid fish migration periods
(Figures 9 and 14).Access construction will continue for
approximately 1.5 years at Watana during Stage I and 2 years at
Devil Canyon duri ng Stage II construct ion (Fi gures 6 and 11).
However,during these time periods,instream activities near
utilized fish habitat will be coordinated to minimize conflict
with identified migration periods.
Bridges,culverts,and other drainage structures will be
install ed duri ng the summer months before,between and after
Arctic grayling and Dolly Varden spawning periods.Activities
not involving instream construction will continue throughout
58
-
-
-
the year.Figures 9 and 14 present the sensitive periods for
specified streams along the access corridor .
.
The USFWS recommended scheduling clearing activities during
winter to minimize aquatic impacts.Because of the
difficulties inherent in wintertime construction,current plans
do not limit clearing to the winter.However,restricting
instream construction during aquatic environmentally sensitive
periods is expected to minimize aquatic impacts.
(c)Water Quality
(i)Imoact Mechanism
Temporary degradations in water qual i ty caused by increased
turbidity,sedimentation and petroleum contamination may change
the species composition and reduce the productivity of the
aquatic ecosystem (Bell 1973,Alyeska ?ipeline Service Company
1974).
(ii)Mitigation
The primary mitigation measures that will be used to minimize
degradations in water quality are:(I)erosion control
measures such as runoff control,stilling basins and
revegetation will be employed as outlined in the BMP Manual on
Erosion and Sedimentation Control (APA 1985b);and (2)the time
period of the construction activity will be minimized so that
degradation in water quality is a short-term,non-recurring
problem.Therefore,water quality degradations from access
construct i on and operat i on are not expected to sign i fi cantly
impact the fisheries resources.Further mitigation is not
expected to be required.
59
(d)Oil and Hazardous Material Soills
ill I
-
-
-
..-
(i)
(ii)
Impact Mechanism
Spills of oil and other hazardous substances into streams can
be toxic to fish and their food organisms.
Mitigation
A Spill Prevention Containment and Countermeasure Plan (SPCC)
will be developed as requ i red by EPA (40 CFR 112.7)pri or to
the initiation of construction.The 8MP manual on Oil Spill
Contingency Planning (APA 1985f)will be used to avoid
potential impacts.
Equipment refueling or repair will not be allowed to take place
in or near floodplains unless adequate provisions have been
made to contain petroleum products.Waste oil will be removed
from the site and disposed using ADEC/USEPA-approved
procedures.Fuel storage tanks wi 11 be located away from
waterbodies and within lined and bermed areas capable of
containing 110 percent of the tank volume.Fuel tanks will be
metered to account for all outflow of fue 1.All fuel 1i nes
will be located in aboveground or ground surface utilidors to
facilitate location of ruptured or sheared fuel lines.
Vehicle accidents,although impossible to totally prevent,can
be minimized by constructing the roads with properly designed
curves to accommodate wi nter dri vi ng cond it ions.The roads
wi 11 have adequate traffi c signs and guardrails.Duri ng the
winter,difficult stretches will be regularly cleared and
sanded.In summer,dust will be controlled with water.
State law requires that all spills,no matter how small,be
reported to ADEC (18 Me 70.080).Personnel will be ass i gned
60
-
to monitor storage and transfer of oil and fuel to identify and
clean up spilled oil and other hazardous material.
All personnel employed on the project,especially field
personnel,will be trained to respond to fuel spills in
accordance with an approved oil spill contingency plan.
BMPM Oil Spill Contingency Plan incl~des:
Guidelines to follow for a training program for involved
personnel.
Actions to take as a first line of defense in the event of
a fuel spill.
Persons to contact in the construction organization and in
state agencies.
locations of sensitive habitat.
Records to keep during an oil spill and cleanup operation.
Oil spill containment equipment will be located onsite and will be
adequate to handl e the 1argest potential spill.Personne 1 wi 11 be
trained in the operation of the equipment,and the equipment will be
inventoried and tested regularly to make sure it is in proper
working order in the event of an emergency (Bohme and Brushett 1979;
lindstedt-Siva 1979).
Impacts from an unavoidabl e major spill wi 11 be assessed by the
Environmental Field Officer (EFO).Appropriate site-specific
mitigation measures will be negotiated in consultation with the
involved resource management agencies.
61
-----------------------------------------
-
(e)Borrow Sites
-
(i)Impact Mechanism
Removal of material may result in erosion,siltation and
increased turbidity.Borrow sites located in floodplains may
impact waterbodies through increased ice buildup from
groundwater overflow and alteration of fish habitat.Fish may
become trapped in excavations within the floodplain.
-
--
(ii)Mitigation
Adverse impacts on aquatic habitats will be avoided or
minimized by application of the BMPM guidelines.The
predominant source of borrow material will be alongside the
access road.Minimal impacts to the aquatic resources are
expected from side-borrow activities.
Borrow material may also be obtained at upland borrow sites
from 10 to 20 acres in size.These borrow sites will be
located away from streams to minimize potential sediment
contributions to waterbodies.Soil stabilization measures will
be undertaken to limit erosion of exposed slopes as described
in the BMP manual on Erosion and Sedimentation Control (APA.
1985b).The borrow sites will be rehabilitated following
closure.The stockpiled overburden will be redistributed and
revegetated.Additional mitigation is not expected.
2.2.2 Monitoring·
Monitoring is recognized as an essential project mitigation feature that
\'Ii 11 prov i de for a reduction of impacts over time.Mon itori ng will be
conducted during project construction and operation:
To insure that environmentally acceptable construction practices,as
defined by the bid specifications,required permits and the BMPM's,
are being employed on the project
62
"""
-
.....
-
To evaluate the effectiveness of the operat i on and maintenance of
mitigation features
To recommend changes in construction practices or mitigation
features to further avoid,minimize,or reduce impacts
Monitoring of the access road construction will verify that proper
construction practices,as detailed in the BMP manuals,are·being
followed.This monitoring activity will cover all aspects of the access
road construction and maintenance.
Construction of the Watana access road is presently scheduled to begin in
1990.From that time until completion of all access roads,an
Environmental Field Officer (EFO)will be present at the sites.On a
daily basis,the EFO will visit areas where construction is occurring.
The EFO will be responsible for compliance with regulatory requirements
and permits.The EFO will be a member of'the APA staff and will report
to the APA's resident engineer and construction manager (Harza-Ebasco
1985a).
Once construction has begun,onsite changes in permit stipulations may be
needed because of accidents or changes in construction techniques.If a
variation is required,the EFO will notify APA's construction manager who
If/ill contact regul atory agencies to amend permits or authorize field
;actions that were not specified in the permits.The construction manager
If/ill report permit violations and issue monthly status reports to the
resource agencies.The construction manager will also be responsible for
notifying the appropriate agencies prior to the commencement of a major
construction activity so that the regulatory agency may request a site
'j nspect ion.
Long-term operational.monitoring will be conducted to evaluate the
effectiveness of the mitigation plan.Arctic grayling populations will
be studied (Harza-Ebasco 1985a)to evaluate the effectiveness of
management pl ans designed to minimize the impact caused by increased
fishing pressure in lakes and streams.The access road will be
63
--
periodically monitored as part of the maintenance schedule.
erosion sites will be identified and corrected and culverts
inspected for debris blockages that could prevent fish passage.
Chronic
will be
Jil!iiroGIi-
-
..-
-!
-
.-
The monitori ng program costs out 1i ned for the proj ect are est i mated in
Table 8.
64
-
-
",..
3.0 ~ONSTRUCTION ZONE
The proposed three-stage development of the Susitna Hydroelectric Project will
\entail construction at two dam sites:Construction on the Stage I development
of the Watana dam is scheduled to begin in 1991 (Figure 6).Site preparation
is expected to start in 1990 and will include camp and village development.
The four turbines are scheduled to be on-1 ine for power production in '1998.
The Stage II development,to be in it i ated in 1996,will i nvo 1ve the
const'ruction of the Devil Canyon dam and temporary camp facilities (Figure
11).In 2006,Stage III construction will raise the crest elevation and
i ncre,ase the generating power of the Watana dam.The addi tiona1 two turbi nes
in th(:!Watana dam are expected to be on-l ine in 2009 (Figure 18).
The construction activities will affect the aquatic resources in the vicinity
of th,e sites.Changes in nearby waterbodies and fish habitat will result;a
loss of habitat will occur at the dam sites.Borrow site excavations will
disturb aquatic habitat at the mouths of Tsusena and Cheechako creeks.Water
quality degradations,including increased sediment levels,,hydrocarbons and
wastewater effl uent contri but ions,may temporaril y decrease aquatic habi tat
quality.Fish will be directly affected as migration barriers will be created
by dam construction.
Mitigation of these impacts in order to preserve the aquatic resources will be
primat~ily accompl i shed by proper adherence to the construction techni ques
presented in the BMPM (APA 1985b,1985c,1985d,1985e,1985f).Additional
mit i gat i ve measures,such as borrow si te rehabil itat ion,will rectify the
impacts associated with dam and camp construction.Monitoring will verify
that construction activities follow the BMPM and that water quality is not
significantly degraded.
3.1 -Impact Analysis
3.1.1 Stage I:Watana Dam and Facilities
The proposed Watana dam and related facilities will be constructed on the
Susitna River between Deadman Creek (RM 187)and Tsusena Creek (RM 182)
65
']l 1 1 I j l J
(7.
(7.
a007 looe 1I00e 1I010 ao 11 a0111 1I0111 1014Oll!aCIII'TION 1I004 aooe aooe
o.o.MOBILIZATION -0202
O~SITE ROADS --0_
03
0_
o~O~
0606SITEFACILITIES.i•••i •••'.
0101
08OOWNSTREAMCOFFEROAM-09
08
09
<>.0-~...........o <><><>'0 DAM EMBANKMENT FOUNDATION
N "~..2 ;:;N",'-......,......"........'2'....,...,................",......"",..."",.................,....................,......'2 DAM EMBANKMENT
'3.3 .-.-RELIC T CHANNEL
I~.~
~-'YL .6--'6 SPILLWAY
1111
.8llATES(REMOVAL).I••ate••
.9.9 ..............2020llATES(INSTALLATION)
2'2'
22- -
--22 POWER INTAKE
,"'.1..........e •••2323
2_H POWER TUNNELS
2~2~
2626POWERHOUSE
2717
182"TRANSFORMER OALLARY/CABLE SHAFTS
2'J19
JOTAILRACE/SURllE CHAMBER --3.
30
3.
32TURBINE/GENERA TORS ......'.'.'.'-'"
33
3Z
3.
3_.............J_I,4ECH./ELECT.SYSTEMS
3~3~
36JS
3737
38I.~I••e'el.,e.-38 TRANSMISSION LINES
'..3939
4040IMPOUNDMENT
UNITS ~~ON LINE 4.41
....Jt...J 4242TESTANDCOMMISSION
43'3
4'.-
J:!!!!!!
-ACCESS/FACILITIES
-EXCAVATION/FOUNDATION TREATMENT
............."...,fiLL
-CONCAElE
.'.'.'el MECHANIl;Al/ELECTAICAL
.....IMPOUNDMENT
SCHEDULE FOR THE CONSTRUCTION OF THE STAGE m ALASKA POWER AUTHORITY
DEVIL CANYON DAM AND RELATED FACILITIES SUSlTNA HYDROELECTRIC PROJECT
HARZA-EBASCO
Figure 18 ENTRIX,INC.
SUSIT:.A JOIN T VENTUREReference:APA 1985i.
i~
.....
,
-
r
.....
[
"..,
(Figure 4).The dam site is probably occupied by burbot,sculpins,and
'Iongnose sucker during the open water season and by these speci es and
Arctic grayling during winter (ADF&G 1981,1983).
Tsusena Creek is a clearwater stream with a drainage area of 144 square
miles (373 __J<m2 ).A waterfall approximately 3 miles (5 km)upstream of
the confluence with the Susitna River blocks upstream fish passage.
!Dolly Varden and scul pin are present upstream.of the fall s on Tsusena
Creek (Sautner and Stratton 1984).Arctic grayl ing,Dolly Varden,and
sculpin utili~e the habitat avail~ble in lower Tsusena Creek (Sautner and
Stratton 1984)and burbot and round whitefish have been observed near its
confluence with the Susitna River (ADF&G 1981,1983).The Arctic
grayling population in the mouth of Tsusena Creek and in the clearwater
!plume which extends into the Susitna River was estimated at 1,000 fish
(ADF&G 1981).Although excellent habitat is present within the lower
reaches of the creek,few Arctic grayling appear to utilize this area for
summer rearing (ADF&G 1983)•
Deadman Creek,a meandering,clearwater tributary of the Susitna River,
supports Arctic grayl ing,Dolly Varden and scul pin (Sautner and Stratton
1984).A waterfall prevents upstream fish passage approximately 0.6
miles (1 km)from the mouth of Deadman Creek.In 1981 and 1982,
approximately 980 and 730 Arctic grayling were estimated to inhabit the
lreach downstream from the fish barrier during summer (ADF&G 1981,1983).
Burbot and longnose sucker have been observed near the creek mouth (ADF&G
1981).The creek has a drainage basin area of 175 square miles (453
kJn2)•
(a)Description
The Watana dam wi 11 be an earth and rockfi 11 structure located
between RM 184 and RM 185 of the Sus itn a River.The Stage I
development of the Watana dam will be built to a crest elevation of
2025 ft (617 m)with a maximum normal reservoir elevation of 2000 ft
(610 m).One outlet facility structure and two power intakes will
be designed to discharge a 50-year flood before the spillway
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overflows (Figure 15).Trashracks with a bar spacing of 6 inches
(15 cm)will be i nsta 11 ed at the intakes and wi 11 be raised and
lowered for cleaning and maintenance.The powerhouse will have four
power generating units.
Clearing will be necessary at the dam and facilities sites and in
the impoundment area.Cover vegetation will be removed at the site
of the dam,airstrip,and construction camp and village.In the
reservoir area,trees will be cleared annually to the expected water
level of inundation to reduce debris accumulation at the dam water
intakes.Cleared material will be stockpiled or burned at specified
disposal sites upstream of the Watana dam site (Figure 15)that will
be subsequently inundated.
Prior to construction of the Stage I main fill structure,the
diversion tunnels and cofferdams will be completed and the river
diverted through the tunnels.Heavy equipment for dam construction
will be brought to the cleared site and assembled in the equipment
maintenance and refueling areas.Construction material will be
stockpiled in the project area.Fill material from the borrow pit
sites and usabl e materi al from excavation of the di versi on tunnel s
will also be stockpiled.All of the rockfill required during Stage
I construction will be obtained from excavations for the powerhouse
and other fac il it i es.Bl ast i ng will be necessary duri ng divers ion
tunnel construction and borrow excavations.During Stage I
construction,rockfill for the dam will be obtained from tunnel and
channel excavations.Water requi red for construction purposes will
be withdrawn from the Susitna River.
The two cofferdams will dewater the construct ion area of the mai n
dam.One cofferdam will be buil t upstream from the damsite and the
other downstream (Figure 15).The upstream cofferdam will be
approximately 800 ft (242 m)long and 450 ft (136 m)wide with a
crest elevation of 1480 ft (450 m);the downstream cofferdam will be
400 ft (121 m)long and 200 ft (60 m)wide.Water blocked by the
upst ream cofferdam wi 11 be diverted into two 36 ft (11 111)diameter
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concrete-lined tunnels about 3700 ft (1130 m)long.Emergency
release facilities will be located in one of the diversion tunnels
after closure to allow lowering of the reservoir for inspection or
repai r of the dam (APA 1985h).The cofferdams wi 11 be constructed
during a two-year period (1992-1993)and will remain in use until
reservoir fill ing begins.At that time,the downstream cofferdam
will be partially removed;the upstream cofferdam will be inundated
by the reservoir.
Gravel mining and material sorting will be required for construction
of the dam and related facilities.During Stage I development,
approximately 10 million cubic yards (7.5 million m3)of material
will be excavated from Borrow Site E between RM 180 and RM 182 along
the north bank of the Susitna River at the confluence of Tsusena
Creek (Figure 10).Borrow activities will be isolated from the
active channels of the Susitna River and Tsusena Creek by natural or
man -made berms to prevent increases in suspended so 1ids.Pri or to
the initiation of lIIateria1 removal,a mining plan will be formulated
in accordance with 43 CFR Part 23;review and approval by concerned
state and federal resource managing agencies will be required.
Current plans propose a moving front excavation beginning at the
downstream end of the borrow site,proceeding in the upstream
direction,and possibly reching depths of 100 ft (30 m).Equipment
capable of removing underwater material will be utilized because of
the high groundwater level at the site.Material will be excavated,
washed,and stockpil ed duri ng spri ng,summer,and fa 11;winter
excavation will be avoided.The gravel will be washed and sorted at
the borrow site.Spoil from gravel processing w'ill be stockpiled
and armored to prevent sediment contributions to the Susitna River
or Tsusena Creek.Spoil will later be used in site rehabilitation.
The wash water will be channeled through settling ponds with gated
culverts between ponds to ensure adequate retention time (APA
1985h).Effluent will conform to ADEC/USEPA standards prior to
discharge to the Susitna River.
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The impervious material required for the construction of the dam
core will be obtained from Borrow Site D (Figure 10).Potential
impacts to Deadman Creek and the Susitna Ri ver are not 1i kely as
exca va t ions will not occur inclose proxi mi ty to these wa terbod i es
and all runoff at the site will be collected and channeled through
settling ponds prior to discharge.Several shallow tundra lakes
within the site will be drained during borrow activities.The
organic layer at the site will be stripped and stockpiled;following
termi na t i on of borrow operations,the site wi 11 be rehab il itated
using the stockpiled overburden.The regions of the site below the
2000 ft (610 m)elevation will be inundated upon reservoir filling
and will.be stabilized to prevent slumping if necessary.
Waste concrete,vegetation and unusable material from construction
sites will be removed to selected disposal sites upstream from the
dam site within the area of permanent inundation (Figure 15).This
material will be armored with riprap or another appropriate
material.Haul roads will be constructed to these sites (Section
2.4.1).
Housing of project personnel will be needed at the Watana site.
During Stage I construction,facilities to house a maximum of 3300
people are planned (APA 1985a).A construction camp and.village
will be built to form two separate communities located less than 0.5
mile (0.8 km)from Deadman Creek and 3 miles (5 km)from the damsite
(APA 1985h).Each development will occupy approximately 170 acres
(68 hal.After Stage I is completed,most of the camp facility will
be demobilized for later use.
The construction camp will contain the management offices,hospital,
recreation hall,warehouses,communications center,dormitories,and
other necessary facilities.The wastewater treatment plant will be
located within the camp boundaries near Deadman Creek.It is
anticipated that the camp,excluding the treatment plant,will be
dismantled at the end of the Stage I development of the Watana dam
construct ion.The camp wi 11 be rebuilt and utili zed duri ng the
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Stage II construction at the Devil Canyon Dam site.Upon completion
of the Devil Canyon dam,the Watana construction camp wi 11 be
reassembled for the Stage III development.
The construction village will be built during the Stage I
deve 1opment and may 1ater be upgraded to a permanent town.The
construction village will house approximately 310 families with
single family and multi-family dwellings provided (APA 1985h).The
village will contain a hospital,school,gas station,fire station,
store,recreation center,and offi ces,as well as res i dences.A
permanent town will be developed at the village site for the
anticipated 130 staff members involved in the operation and
maintenance of the dam.
Construction uses for water will require withdrawal from waterbodies
in the vicinity of construction activities.The Susitna River will
be the source for water to be utilized in dam construction.Water
wi 11 be utili zed throughout the construction -process in act i vi ties
such as concrete production,aggregate washing and dust control.
Concrete wastewater pH levels are high (10 +)and will be
neutralized prior to discharge.If additives containing toxic
chemi cal s are ut il i zed,the effl uent wi 11 be fil tered pri or to
discharge.A water appropriation permit appl ication will be filed
with the ADNR as required by AS 46.15.070.In addition,the ADF&G
and the ADEC will be consulted for approval and permitting of water
withdrawal.
Water will be withdrawn from Deadman Creek approximately 7 m'iles
(11 km)upstream from the mouth and treated to conform with the
primary and secondary requirements of the ADEC/USEPA for domestic
use in the construction camp and village.Wells may be drilled near
Deadman Creek to prOVide an additional water supply (APA 1985h).
The water supply system will be reviewed byADEC as required by 18
AAC 80.100.An estimated 0.5 cfs (208 gallons per minute)will be
wi thdrawn duri ng the peak demand peri ods whi ch wi 11 occur duri ng
summer construction.Construction personnel will be reduced by
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approximately 2/3 during the winter months.The minimum flow for
the lowest flow month,which will occur during the winter,was
estimated to be 3200 gallons per minute at the withdrawal site.
Therefore,significant adverse impacts are not anticipated from the
maximum water supply withdrawal which represents less than one
percent reduction ·in flow during the open water season and less than
five percent during the winter.
A wastewater treatment facility will be constructed to process the
wastewater from the construction camp and village prior to discharge
into Deadman Creek.Waste will be stored in a lagoon system until
the facility is operational.Sewage from the construction camp and
vi 11 age will be pi ped to the facil ity.Waste from the chemi ca 1
toilets located within the construction areas will also be treated
at the facility.The sewage treatment plant will include a
biological treatment lagoon to provide secondary treatment to assure
conformance wi th the ADEC/USEPA standards..A mechani cal aerator
will assist in maintaining biological activity in the lagoon during
the winter.Treated sludge will be disposed with the solid waste in
ali ned,bermed,and capped san i tary 1andfi 11 to the southeast of
the camp and Village (APA 1985h).
The eff1 uent outfall wi 11 be located downstream from the water
withdrawal site and approximately 1.5 miles (2 km)upstream of the
confl uence of Deadman Creek wi th the Sus itna River.Thorough and
rapid mixing is expected as the outfall will be located in a
turbul ent secti on of the creek.Under the estimated worse case
conditions,a maximum effluent discharge of 1.5 cfs and a winter low
flow in Deadman Creek of 27 cfs,the BOD and TSS concentrations will
be 2 mg/l after complete mixing.Degradation of the water quality
in Deadman Creek or the impoundment area of the Susitna River is not
expected due to the presence of the effluent.
Hazardous wastes will be temporarily stored onsite in a bermed and
1 ined area and then removed for disposal.Waste oils containing
trace metal s requi re handl ing as a hazardous waste under 40 CFR
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261-265.Solvents and other chemicals of concern,including anti-
freeze,hydraulic oil,grease and paints,are also toxic to aquatic
life and will be stored in the hazardous waste area.Vehicles will
be ma i nta i ned to prevent ant i freeze,hydraul ic fl ui d and fuel from
contami nat i ng nearby water.Fue 1 wi 11 be stored and used in 1 arge
quantities during construction.Fuel tanks will be surrounded by
containment dikes capable of containing 110 percent of the tank
capacity.Fuel storage areas will be lined with impermeable mater-
ials to prevent fuel contamination of groundwater.Vehicle fueling
will be restricted to areas where runoff will be collected.Oily
water runoff from the dam site and surface runoff at the vehi cl e
maintenance areas,shops and related facilities will be collected
and treated.All fuel spills will be reported to the ADEC as
required by law.The contractor's Spill Prevention,Containment and
Countermeasure plan (SPCC)will be developed and personnel trained
prior to the initiation of construction as described in Section
2.1.1.
A 2500 ft (758 m)temporary airstrip will be built approximately 1
mile (1.6 km)from the campsite at the 2500 ft (762 m)level (Figure
15)•The ai rstri p wi 11 1 ater be upgraded to a permanent ai rstri p
which will be 6500 ft (1980 m)long.
(b)Potential Impacts
The Stage I construction of the Watana dam and camps wi 11 have a
number of effects on the Susitna River,nearby tributaries and their
biota.Some effects·will be the direct result of construction
activities,while other effects will result from alteration of the
river environment during construction.Impacts will vary in
duration and overall extent,some being temporary or localized while
others will be permanent or more widespread.
(i)Cofferdams and Diversion Tunnels
The first major phase of Stage I dam construction invol ves
placement of the two cofferdams and the permanent dewatering of
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0.75 mile (1.3 km)of riverbed at the damsite.Fish normally
using this stretch are anticipated to move into adjacent
habitats and the effects on population size are expected to be
minor.The dewatered area will eventually be totally covered
by the Stage I II Watana dam;thus,the effect wi 11 be a perm-
anent but relatively minor loss of aquatic habitat.The Stage
I dam will cover approximately 300 ft (91m)less riverbed on
the downstream side (Figure 19)than the Stage III dam.
Upstream fi sh movements through thi s reach wi 11 be permanently
blocked when the Stage I development occurs as water velocities
within the tunnels will act as a barrier.to upstream fish
passage.Arctic grayling seem to predominantly return to the
stream utilized in previous migrations from the mainstem (ADF&G
1983).However,some Arctic grayling are expected to migrate
to other streams upstream and downstream along the Susitna
River (ADF&G 1983).For example,Arctic grayling tagged at
Deadman Creek have been recaptured at Tsusena and Fog creeks
(ADF&G 1981,1983).The permanent upstream fish passage
blockage between Deadman and Tsusena creeks 1s not expected to
cause major degradation in the aquatic resources as migration
appears to occur in both the upstream and downstream
directions.Interstream movements from Deadman Creek will
remain possible in the upstream direction;whereas interstream
movements will remain possible downstream from Tsusena Creek~
The cofferdams will impound water and raise water levels
upstream from the damsite.During the summer,a mean annual
flood event wi 11 cause backwater effects for several mi 1es
upstream.The diversion tunnels will be capable of discharging
typical winter flows without creating stage increases upstream
of the cofferdams.Aquatic impacts within the impoundment area
have been described by Entrix (1985)and APA (1983b,1985g).
Experiments with fish transport indicate that fish are
adversely affected when exposed to velocities in excess of 9.0
74
SCALE
o 500 Ft.,,
STAGE I
RESERVOIR
EL.2000
STAGE 1lI
RESERVOIR
EL.2185
I
I
J
".1
.",,-
/'
Fi11lcl1 ~./
.STAGEJir----iSTAGqDAM~(DAM~~
\4,
~
"
"....."~\//
"\\'~I
\\/
\ \I\..
--STAGE I DAM
---STAGEIDOAM
J »i ~I 1 1 1 )1 1 J 1 I I
-
'J
N
~
-..I
U1
PLAN VIEW OF STAGES I AND mOF THE
WATANA DAM
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 19
ENTRIX,INC.HARZA-EBASCO
SUSITNA JOINT VENTURE
I""'"
I
.-.
I
ft/sec (2.7 m/sec)(Taft et al.1977).If river transport
mechanisms move rocks and other materials into the tunnels,or
if the tunnel walls are not smooth,fish may be damaged through
abrasion while being transported downstream.Tunnel velocities
are expected to exceed 20 ft/sec (6 m/sec)during much of the
summer (APA 1985h).However,little impact on populations is
expected since relatively few resident fish are believed to
o.ccupy the mainstem area immediately upstream from the tunnels
duri ng the summer.Duri ng the wi nter months,entrance
velocities into the tunnels are expected to be in excess of 15
ft/sec (5 m/sec)(APA 1985h).Arctic grayling and other
resident fish overwintering in the vicinity are likely to be
entrained into the tunnels,and fish mortality through abrasion
would probably result.
Several agencies (ADF&G and USFWS)suggested that a fish screen
at the intake of the diversion tunnels would avoid fish
entrainment.However,the habitat in the vicinity of the
diversion tunnel intakes is expected to be poor and most fish
are likely to seek alternative habitat such as tributary
mouths.The cost associ ated with the construction and
maintenance of a screen does not appear justifiable relative to
the small number of fish potentially transported downstream.
Habitat immediately downstream of the diversion tunnels will be
impacted by the high discharge velocities at the downstream end
of the tunnels.The high velocities will deter fish from using
the area immediately downstream from the tunnel s (Bates and
Vanderwalker 1964;Stone and Webster 1976)during dam
construction and operation.In addition,gravels,sands and
silts will be scoured from the immediate area of the tunnel
outlet,and suspended sediment levels will initially increase.
However,the channel bed in the vicinity of the outlet is
expected to rapidly establ ish an equil ibrium condition.The
scouring will not measurably increase the turbidity or the
suspended sediment levels in the Susitna River.
76
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(ii)Borrow Activities
Impacts associated with borrow activities include habitat
alterations and temporary reductions in habitat qual ity from
water quality degradations caused by increases in suspended
sediments and hydrocarbons.Along-term aquatic impact is
expected due to the excavation in the vicinity of the mouth of
Tsusena Creek.The volume of material to be removed will
result in a large pit that will become filled with water.This
pit will be rehabilitated by contouring and redistributing
materi a1 to produce increased 1ent ic habi tat rep 1 ac i ng lost
riparian and upland habitat as described in Section ,3.2.1.
Increases in suspended sediment 1evel s and hydrocarbon
contami nat i on of nearby waterbodi es wi 11 cause decreases in
primary production and may injure fish (Section 2.1.1(b»).
At Borrow Site E,the installation of a stream crossing
structure will introduce small amounts of hydrocarbons and
suspended sediments into Tsusena Creek and the small unnamed
creek.These water quality degradations are expected to occur
during instream construction.long term increases in suspended
solids levels in Tsusena Creek will be avoided by the natural
or man-made berm isolating borrow activities.A buffer will
a1 so be rna i nta i ned between the Sus i tna Ri ver and the borrow
site (Figure 20).Arctic grayling,Dolly Varden,and other
resident species present in the tributary mouth are likely to
seek alternative habitat.The small creek may be diverted
around the borrow site.Few arctic grayling or other resident
species are expected to inhabit the lower reaches of this
creek;a survey of the fi sh resources of thi s creek has not
been conducted.To avoid or mlnlmlze hydrocarbon
contamination,fuel utilized in borrow activities will be
stored and equi pment refuel ed ina bermed and 1i ned area.
Residual amounts of hydrocarbons will probably enter the
Susitna River.The small amounts of hydrocarbons contamination
is expected to be insignificant when mixed in the Susitna River
77
J J )J II•I }I j J ~
,f I -))1 »;I .~
LE~
-.---BORROW SITE LIMIT
____MAXIMUM NORMAL DEVIL
CANYON RESERVOIR
LEVEL (1455 FT.)
II ~I ~J ~,II'BUFFERS TO BE
MAINTAINED
TOPOGRAPHIC CONTOURS
STREAM MARGINS
tttfttJ BORROW SITE E
.'.,'..'
//~~;'.J,....a~l?"·""--,....At'~!~l:;;urq
#.,oJ",1f:(ll'i'(~fm1
•A ..'~}r,I);:,:L:;:-r:!l':
400 100 n:n
~
o
iI<:AUO@
-.J
(Xl .;?~~/'~;:;.~~~4~~~ll\'il~~~flil;f.W.l.I~.~'!!\llil:lllllii~.~
.~".
.'--..-'.••_/................~.-)'~~I;'llllJ.i.~~r ,//_._pl'~./....,.-...
BORROW SITE E ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:APA 1983.Figure 20 ENTRIX,INC.
HARZA·EBASCO
SUSITNA JOINT VENTURE
-'
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(i ii )
unless a fuel splll occurs.Accidental petroleum spills will
be avoided or contained according to the BMP Oil Spill Plan
detailed in Section 2.1.1 (APA 1985f).
Excavation,in accordance with the BMPM on Erosion and Sedi-
mentation Control (APA 1985b),'is not expected to have signi-
ficant aquatic impacts at upland sites such as Borrow Site D
and Quarry Site A.Quarry Site A is ,not anticipated to be
utilized during Stage I.Suspended sediment -increases at all
borrow sites will be avoided or minimized as described by
retaining buffers at stream margins,collecting runoff and
monitoring settling pond effluents.Buffer zones of uncleared
vegetation or overburden will reduce sediment contributions to
streams and lakes.To minimizle the impacts associated with
erosion (Section 2.1.1(b)),runoff will be channeled away from
waterbodies providing aquatic habitat into settling ponds.The
effl uent di scharged from the settl i ng ponds will be moni tored
and the ponds will be dredged when the water quality approaches
the AOEC/USEPA standards.Thla dredged sediments wi 11 be
stockpiled and armored with gravel to prevent sediment contri-
but ions to nearby waterbod i es .The sed i ments may be used in
site renovation.
Fi 11 Pl acement
The movement and usage of fill materials for the cofferdams and
the main dams will be conducted according to BMPM guidel ines
(APA 1985b)to avoid or minimize turbidity and siltation
impacts at the dam site and cons truct i on camps.Duri ng the
transport,storage and placement of the fill material used in
construction,material spills will be avoided to prevent
impacts to Tsusena Creek and the Susitna River.A major spill
introducing high suspended sediment levels (in excess of 20,000
mg/l)into a clearwater stream could cause fish mortality
(Langer 1980).However,runoff control structures will be
installed on the banks of Tsusena Creek to channel surface
runoff into settling ponds.
79
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The placement of fi 11 materi a1 duri ng cofferdam construct ion
will rai se suspended sediment 1evel s downstream.The
cofferdams will be constructed during the summer-and the
resulting increase in suspended sediments relative to the
highly turbid natural summer conditions is not expected to
significantly affect the aquatic resources downstream.
Residual increases in mainstem turbidity are expected to be
negligible.
(iv)Water Removal
All water removal operations win adhere to th~BMPM guidel ines
(APA 1985c)in order to avoid or minimize potential impacts.
All water intakes will be screened and sized according to the
ADF&G intake design criteria to prevent fish entrapment,
entrainment or impingement.Since low volume pumps .equipped
with proper intake screens will be used,it is expected that
the number of affected fish will be low.
The estimated 0.5 cfs which will be needed to meet peak
domestic use demands in both the construction camp and
construct ion vill age presents 1ess than a one percent reduction
in Deadman Creek flow during the average open-water season,and
1ittle impact is expected to resul t from decreases of thi s
magnitude.A maximum reduction of approximately 8 percent is
expected duri ng the winter peri od;overwi nteri ng 0011 y Varden,
Arctic grayling and sculpin which may be present in deep pools
downstream .of the intake are not likely to be adversely
affected by the water withdrawal.
Installation of the water withdrawal structure will follow the
BMPM gUidel ines (APA 1985c).Turbidity and suspended sediment
1evel s wi 11 increase temporaril y duri ng i nsta11 at i on of the
water intake system.Impacts associated with this instream
activity (Section 2.1.1(b»will be short in duration and will
80
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(v)
cause negligible degradations in the aquatic resources if
proper construction practices are used.
liguid and Solid Waste Management
Potential aquatic impacts are not expected from the collection
and disposal of solid wastes in conformance with the BMPM (APA
1985d)._Residual impacts from waste disposal will not
significantly affect the aquatic habitat or the productivity of
the aquatic system.All necessary permit applications for
discharge will be obtained from_the ADEC,USEPA,ADNR and PHS
and include the ADEC wastewater and waste disposal permits,a
Federal Water Quality Certification and a National Pollutant
Discharge and Elimination System Permit.
Aquatic impacts on the Susitna River from wastewater generated
during construction activities are not expected.Concrete
wastewater is highly basic with an average pH level greater
than 10.The wastewater will be neutralized prior to discharge
to avoid increases in pH levels of the nearby waterbodies.
During concrete production,thE!use of additives containing
toxic chemicals will be minimized.The effluent will be
filtered if additives containing toxic chemicals are used.
Duri ng the Stage I development,the construction wastewater
will be treated and discharged into the Susitna River;rapid
mixing is expected to occur in the large,swift river.
Impacts on fi sh habi tat located downstream from the effl uent
outlet into Deadman Creek may include increased nutrient
1oadi ngs and increased temperatures.Arct ic grayl ing,the
primary species in Deadman Creek,are considered to be very
sensitive to alterations in watlar quality (Scott and Crossman
1973,McLeay et al.1984).Secondary treatment will avoid many
of the problems associated with primary treatment,such as
decreased dissolved oxygen and increased biochemical oxygen
demand (BOD)and bacterial counts (Warren 1971).If
81
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disinfection is required,an additional lagoon will be needed
to provide the residence time to reduce the total residual
chlorine to the USEPA chlorine standard of 2 mg/l for
salmonids.The lagoon system 1J'1ill be utilized to cool the
effluent temperatures to match the temperatures within the
stream.The effluent BOD and the concentration of total
suspended solids (TSS)are both E!stimated to be 30 mg/l,levels
which conform to water quality standards set by the Clean Water
Act (USEPA)and the ADEC Waste~later Disposal regulations (18
AAC 72).Effluent from construction and domestic activities
will be mon i tored to veri fy conformance wi th ADEC/USEPA
standards and the effluent disposal permits.
Although .the treated effluent will introduce increased levels
of phosphorus and nitrogen into Deadman Creek,a large increase
in product ion in Deadman Creek 11 s not expected.The effl uent
outfall in Deadman Creek will be located in a turbulent section
and thorough and rapid mixin~,is expected.The maximum
effluent discharge from Watana camp is expected to be 1.5 cfs;
the 1 in 20 year,30-day 10~1 flow for Deadman Creek is
estimated to be 27 cfs (APA 1983c).Following mixing,at this
low flow,the BOD and TSS 1eve 1sin the effl uent wi 11 be
diluted to approximately 2 mg/l.Nitrogen and phosphorus
loadings will be similarly diluted.The water quality in
Deadman Creek is thus not expected to be significantly degraded
by the effluent contributions.
The di 1uted effl uent is not expected to degrade the water
qua 1i ty in the Watana i 1'I'lpoundment by a measurabl e amount.
During Stage I dam construction,the effluent from the
wastewater treatment pl ant will rapidly become mixed with the
water in Deadman Creek;max;mum d il ut ion is expected before
Deadman Creek enters the impoundment created behind the
cofferdams.The maximum Stage I normal reservoir elevation
will be 2000 ft (610 m).The outfall will be approximately 100
ft (30 m)upstream along Deadman Creek from the reservoir at
82
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this elevation.Although complete mlxlng of the effluent may
not occur in the 100 ft (30 m)rl~ach of creek,the 1arge vol ume
of the reservoir is 1i ke1y to assimil ate the effl uent
completely and water qual ity degradations in the impoundment
are expected to be undetectable.
(vi)Disposal Sites
Adherence to the BMPM guidel i nes (APA 1985b)for di sposal of
material will avoid or minimize adverse impacts on the aquatic
resources from increased suspended sed i ment 1eve1 s.Runoff
control berms will minimize turbid water contributions to
nearby streams and 1akes.Di sposed materi a]wi 11 be covered
with a layer of coarse gravel or shot rock to minimize erosion.
Suspended sediment increases will be temporary and residual
aquatic impacts are not expected.
(vii)
The disposal sites will be
Watana reservoir filling.
duri ng i nundat i on;however,
water in the reservoir,
insignificant.
Clearing
partially inund.ated upon Stage I
TUirbidity may increase locally
relative to the large volume of
turbidity increases will be
J~
-
(viii)
Increases in local runoff may occur due to clearing activities
and cause erosion,increased turbidity,and increased dissolved
solids (Likens et al.1970;Bormann et al.1970;Pierce et al.
1970).The aquatic impacts are discussed more fully in Section
2.1.1(b)although the residual aquatic impacts from clearing
activit i es will not requi re additional mitigation beyond
adherence to the BMPM (APA 1985b).
Fuel and Hazardous Materials
Waterbodies in close proximity to the construction sites may
receive small amounts of hydrocarbons.Storm runoff from the
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camp,village and construction sites may contain hydrocarbons
and sediments.By providing the proper drainage facilities and
ponding areas described in the BMPM on Fuel and Hazardous
Materials (APA 1985d),and if ne1cessary,pump stations to pump
contami nated water to the treatment facil i ty,most oil y and
silty water will be prevented from reaching Tsusena and Deadman
creeks.The small lakes at the village site will be more
susceptible to intrusions of oily water.Runoff control
measures such as trenches alongside roadways will collect
runoff to avoid impacts to the lake.The water quality is not
expected to be detectab1y impacted by the hydrocarbons in such
small quantities.
An accidental spill,however,would severely affect the aquatic
bi ota in nearby creeks and 1 a,kes as descri bed inSect ion
2.1.1(b).Accidental oil spills;will be avoided or contained
as descri bed in the BMP manu,a 1 on Oi 1 Spi 11 Cont i ngency
Planning (APA 1985f).
(ix)Blasting
Current construction plans do not require instream blasting.
81 ast i ng is planned for areas 500 feet (150 m)or more from
streams.A review of the effects of blasting on aquatic 1 ife
(Joyce et a1.1980a,Te1eki et a1.1978)indicates that effects
from such blasting would probably not be lethal to aquatic
organisms (at least with charges of less than 200 kg of TNT).
The transmitted shock waves from the blasting may disturb fish
and perhaps temporarily displace them from areas near blasting
activity.This type of behavior is well documented for a
variety of noise sources (Vanderwalker 1967;'USEPA 1976;
Latvaitis et al.1977).Secondary effects of blasting may
include small increases in turb'idity and s"iltation caused by
loosened soils and dust.Instream blasting will adhere to the
ADF&G gUidelines (Table 9)for the Susitna River.The location
and amount of blasting planned during the Watana dam
84
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1 Required distances for charge weights not set forth in this table
must be computed by linear interpolation between the charge weights
bracketing the desired charge if the charge weight is between one
and 1000 pounds;example:for 15 pounds of explosive in rock
substrate -required distance =
15 1bs-l0 1bs170feet+25 lbs-l0 lbs (270 feet-170 feet)=203 feet;
for charge weights greater than 1000 pounds,the required distance may be
determined by linear extrapolation.
Source:Edfelt 1981
85
(x)
construction is not expected to significantly impact fish.
Quarry blasting activities are not expected as the rockfill is
expected to be stockpiled from diversion tunnel excavations.
Recreational Impacts
Construction and operation of th,e dam and camps will result in
increased access to an area previously exposed to minimal
fishing pressure.The areas expected to sustain the heaviest
harvest pressure would be those stretches of Deadman and
Tsusena Creeks and the Susitna Riiver that are easily accessible
from the camps and the dams i te.Impacts woul d be as descri bed
in Section 2.1.1(b).
-
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3.1.2 Stage II:Devil Canyon Dam and Facilities
The Devil Canyon dam will be situated on the Susitna River at RM 152
approximately 2 miles (3 km)downstream from the Cheechako Creek
confluence (RM 154)and represents Stage II of the Susitna Hydroelectric
Project.At the Devil Canyon dam site,the Susitna River is confined to
a canyon approximately 600 feet (180 m)deep and 200 to 400 feet (60 to
120 m)wide at river level.The high velocities in the Susitna River are
bel ieved to deter fish from utilizing habitat at the dam site (ADF&G
1981).Fish are usually prevented from migrating upstream of Devil
Canyon because of the high water velocity.However,a relatively small
number of chinook salmon have been observed upstream of the Devil Canyon
dam site (ADF&G 1981,1983;Barrett et al.1985).No more than 46
chinook salmon per year have been observed upstream of the Devil Canyon
dam site between 1981 and 1984 (ADF&G 1981:.1983;Barrett et al.1985).
Cheechako Creek is a clearwater stream supporting Arctic grayling,Dolly
Varden and probably sculpin (Barrett et al"1984).A few chinook salmon
are known to utilize the lower reaches of Cheechako Creek;between 1981
and 1984,a maximum of 29 chinook salmon WE~re observed in Cheechako Creek
(ADF&G 1981, 1983,Barrett et al.1985).During the low summer flows
associated with the operation of Watana dam,chinook salmon are likely to
pass the Devil Canyon dam site.
86
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(a)Description
The Devil Canyon dam will be located approximately 32 miles (53 km)
downstream from the Watana dam site.During the Stage II
development of the Susitna Hydroelectric Project,a thin concrete
arch dam wi 11 be bui 1t at the downstream end of Devi 1 Canyon and
connect at the south end to an ~arth and rockfill saddle dam built
to provide closure of a low area at the south abutment (Figure 16).
A perched 1 ake in the saddl e dam area wi 11 be drained duri ng
construction.The concrete dam foundation will cover about 90 ft
(27 m)of river bottom.Construction of the dam will require
excavation in the river channel by blasting or mechanical methods.
The reservoir behind Devil Canyon will cover 7800 acres (3120 ha)
and wi 11 be about 26 mil es (42 km)long and not more than 0.5 mi 1e
(0.8 km)wide.
The concrete dam and foundation will be 646 ft (195 m)high with a
crest elevation of 1463 ft (446 m)and a crest length of 1260 ft
(385 m).An estimated 1.7 million cubic yards (1.3 million cubic m)
of concrete wi 11 be needed to construct the arch dam.Waste
concrete will be stockpiled in a disposal area and concrete
wastewater will be channeled through settling ponds and neutralized
prior to discharge into the Susitna River.The saddle dam will be
950 ft (287 m)across and 245 ft (74 m)high with a crest elevation
of 1472 ft (449 m)and wi 11 requi re about 1.2 mi 11 ion cubi c yards
(912,000 m)of earth and rockfill material (APA 1985a).Impervious
material will be hauled from Borrow Site 0 along the main access
road to the Devil Canyon site.Material will be excavated and
processed as described in Section 3.1.1(a).
Filter material and concrete aggregate will be obtained from the
Susitna River at the dewatered dam site,Borrow SiteG and Quarry
Site K.Borrow Si te Gis located at the confl uence of Cheechako
Creek and the Susitna River.A pit excavation is expected at Borrow
Site G.The mouth of Cheechako Cr'eek wi 11 be diverted to the
eastern boundary of the site.OVE!rburden wi 11 be removed and
87
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I""'"
,
-
-
stockpiled or buried.Gravel washing water will be channeled
through settling ponds.Approximately 40 acres of Borrow Site G are
expected to be disturbed.Quarry Siite K is approximately 400 ft
higher in elevation and 1.5 miles (2 km)upstream from the mouth of
Cheechako Creek.Overburden will be removed and stockpiled for use
in site reclamation following the termination of quarry activities.
Washing of quarry material will not be necessary.The locations of
sites G and K are shown in Figure 17;other borrow sites may be
utilized if material quantities are not adequate at sites G and K.
As wi th the Watana dam,the Dev;i 1 Canyon dam wi 11 have an
underground powerhouse,intake structure,outlet works,and main and
emergency spi 11 ways.The intake structures wi 11 be equi pped wi th
trashracks with 6 ;nch (15 em)bar spaci ng to prevent debri s from
being drawn into the powerhouse.A :~8 ft (12 m)diameter tailrace
tunnel wi 11 convey the turbine di scharge approximately 1.3 mil es
(2.2 km)downstream from the arch dam.Outlet facilities will be
designed to discharge a 50-year flood.Four 20 ft (6 m)diameter
tunnels will lead from the intake structure to the underground
powerhouse (APA 1985a).
The river will be blocked above and below the construction site by
cofferdams.The flow will be diverted into a 35 ft ell m)diameter
horseshoe tunnel,1490 ft (451 m)long,and discharged back into the
river channel.The upstream and downstream cofferdams will be about
400 ft (120 m)long and 200 to 400 ft (60 to 120 m)wide (Figure 16)
(APA 1985a).
The construction camp and construction Village to house a maximum of
1900 persons will be located approximately 2.5 miles (4 km)
southwest of the dam site (Figure 21).The camp will include
dormitories,cafeteria,warehouses,offices,hospital,and
recreati onal buil dings.The vill age wi 11 contai n housi ng for 150
fami 1 i es and wi 11 include a school,stores,and a recreat i on area.
The camp will be approximately 0.5 mne (0.8 km)from the Village.
Both developments will be more than 700 ft (210 m)above the Susitna
88
-
--
Ri ver and more than 4000 ft (1200 m)from the edge of the canyon
(Figure 21).Water,sewage,and solid waste disposal facilities
will be shared by both developments.Water will be withdrawn from
the SusitnaRiver and the secondary tlr'eatment system,simil ar to the
facility at the Watana site,will discharge effluent into the
Susitna River approximately 1000 ft (305 m)downstream of the water
intake.
The southern boundary of the camp and the vi 11 age approach wi th in
200 ft (60 m)of the upper reaches of Jack Long Creek.Arctic
grayling,rainbow trout,slimy sculpin,chinook,pink,chum and coho
salmon are known to util ize Jack Long Creek (Sautner and Stratton
1984).A small unnamed creek,which enters the Susitna at RM 150,
drains a series of small lakes 3000 ft (900 m)to the east of the
camp.The creek is paralleled by the sewage outfall line for
approximately 1000 ft (300 m)or about 20 percent of its length.
The unnamed creek and lakes appear to provide Arctic grayling,Dolly
Varden and sculpin habitat.A few chinook salmon,.Arctic grayling,
and Dolly Varden are found in the lower reaches of Cheechako Creek
(ADF&G 1983).
As at the Watana dam (Section 3.1.1),fuel and hazardous materials
will be stored and utilized onsite.The fuel storage area will be
located ina lined and di ked areal on the south side of the
construction camp approximately 300 ft (91 m)higher in elevation
and 1500 ft (460 m)away from Jack Long Creek.
Both the camps and the vi 11 age are temporary developments to be
dismantled and removed when the Stage II construction of the Devil
Canyon dam is completed.Permanent personnel responsible for
operation of the Devil Canyon dam will live at the Watana town.No
airstrip will be built;air access willl be provided by the permanent
runway at Watana.
89
---------.-
]
@
100II 'I""'.
!!IiiiiiiiiiI
~.-1I
SCAli
~,.0 W,.,.,.N"
."
LEGEND
MAIN ACCESS ROAD
_CONSTRUCTION ROAD
------RAILROAD
_..._STREAM MARGINS
__- -TRANSMISSION LINES
1
~~~~'W LINES •~,v"!~~
t
Ie
lIU)1·u~
)\\./._,
!/\
JjJJ}1
"
"..,-\.
1I)
-)
..0
::>
PLAN VIEW OF THE DEVIL CANYON DAM AND RELATED
FACILITIES ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:APA 1985j.Figure 21 ENTRIX,INC.
HARZA·EBASCO
SUSITNA JOINT VENTURE
,....
I
.....
(b)Potential Impacts
The adverse impacts upon the aquatic resources at the Devil Canyon
dam site are expected to be similar'to,but of lesser magnitude
than,those at the Watana site (Section 3.1.1).Impacts from
constructi on at Devil Canyon will be primari ly restricted to the dam
site.Temporary impacts result i ng from the camp and vi 11 age
construction and operations are expected to be limited to the area
immediately surrounding the construct"ion site.
..,..
,....,
I
-
(i)Cofferdams and Diversion Tunnel
Upon completion of the cofferdams and diversion tunnel,
approximately 1,100 ft (335 m)of riverbed will be dewatered
between the cofferdams as at the Watana dam (Sect ion 3.1.1).
The dam foundation will permanently cover about 90 ft (27 m)of
river bottom.Because the turbulence at the site is believed
to deter fish from utilizing the aquatic habitat in the canyon,
dewatering will likely have a minor impact upon availability of
suitable aquatic habitat.
The cofferdams will create a permanent upstream migration
barrier to fish in Devil Canyon.Under natural conditions,
most fish species are unable to migrate upstream through the
canyon due to high water velocities.In 1981 through 1984,
chinook salmon were observed spa.wning in four tributaries and
tributary mouths upstream of the dam site.However,few
chinook salmon utilize this reach of river (21 to 46 fish
observed per year)(ADF&G 1981,1983,Barrett et ale 1985)and
therefore the loss of chinook salmon spawning habitat upstream
of the damsite is expected to be small.
Fish migrations downstream will remain possible although high
mortality is likely if fish are abraded by the tunnel walls.
Fi sh migrating downstream after constructi on of the cofferdams
may be entrained into the diversion tunnel.Entrained fish are
91
....
....
,-
!
(ii)
1i ke ly to be damaged by contact wi th tunne 1 wall s.Under
natural conditions,fish present in the Susitna River may
migrate downstream through Devil Canyon.However,the extent
of downstream fish migration is assumed to be small.
During the winter,the diversion tunnel will be partially
closed to impound a head pond to prevent ice problems;the
impoundment may provide overwintering habitat for Arctic
grayling.Overwintering fish in the vicinity of the diversion
tunnel intake are likely to become entrained into the tunnel
and damaged while being transported downstream.However,a
1arge impact on overwi nteri ng fi sh is not exp.ected as the'
habitat in the vicinity of the intake is expected to be poor
compared to habitat available elsewhere in the impoundment .
Borrow Activities
The greatest impacts during construction of the dam and related
facilities are likely to be associated with gravel mining and
processing in Borrow Site G.Impacts associated with suspended
sediment and hydrocarbon increases are described in Section
2.1.1 (b).Suspended sediment and hydrocarbon contri but ions to
ItheSusitna River from gravel mining will be controlled by
maintaining buffer zones and Iberms and by collecting and
circulating turbid runoff through sediment ponds prior to
discharge.Potential migration barriers to fish in Cheechako
Creek will be avoided by diverting the creek to the eastern
boundary of the·site and maintaining a buffer between the creek
and the excavation area.The habitat in the mouth of Cheechako
Creek will be lost as Borrow Site G will be permanently
inundated by the Devil Canyon reservoir.
The Stage II development will change the quality of the aquatic
habitats associ ated with the rehabil itated Borrow Site E.The
operation of the Devil Canyon dam will impound a reservoir to a
maximum normal operating elevation of 1455 ft (443 m).The
92
,....
,"'""
(iii)
(i v)
reservoir will partially inundate!the rehabilitated Borrow Site
E as shown in Figure 20.Following inundation,the water
quality of the rehabilitated pit will reflect the reservoir
water quality characteristics.The productivity in the Devil
Canyon reservoir is expected to be poor because of high
turbidity levels,cool tempercltures and low nitrogen and
phosphorus nutrient levels.However,the tributaries will
contribute clear water with higher nutrient levels;therefore,
fish utilization around the areas of tributary inflow,such as
at the mouth of Tsusena Creek,is expected to be higher than
elsewhere in the reservoir.A detailed description of the
water quality and habitat availability in the reservoir is
conta i ned in Exh i bi t E,Chapter 2 of the Li cense App 1 i cat ion
(APA 19S3a)and license Application Amendment (APA 19S5h).
Disposal Sites
Di sposa1 sites wi 11 be located in accordance with the BMPM
gUidelines (APA 19S5b)to avoid or minimize the impacts on the
aquatic organisms described in Section 3.1.1(b).Runoff
control structures will be installed to avoid increases in
turbidity or organic contributions to waterbodies in the
vicinity.Disposal sites will be situated upstream from the
dam site (F i gure 16)and wi 11 ble permanently i nunda ted duri ng
reservoir filling.Prior to inundation,disposed material will
be stabilized with a riprap cover to minimize erosional
impacts.Res i dual impacts on the!aquat ic resources of the area
from operation or inundation of the disposal sites are expected
to be negligible due to the large volume of the reservoir.
Water Removal
Aquatic impacts from water removal for construction and camp
use from the Susitna River have been described in Section
2.1.1(b).Required withdrawal discharges are expected to be
insignificant relative to the Susitna River discharge.
93
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(v)
(vi)
Liquid and Solid Waste Management
Liquid and solid wastes could degrade the water quality inthe
c1 earwater streams and the Susitna River.To minimi ze water
quality degradations,all process waters will be treated prior
to discharge to the Susitna River.Wastewater from the
construction camp will be collected and treated in the Devil
Canyon sewage treatment plant.The treated effluent,less than
1 cfs,will not measurably decrease.the waste assimilative
capacity of the Sus itna Ri ver and is not expected to have a
significant effect on the aquatic environment.Water used in
the concrete batching process,storm drainage,and oily water
runoff from the construction camp will be collected and treated
in sett1 ing.ponds prior to discharge as described in Section
3.1.1(b).Required drainage facii1ities and retention ponds,as
spec;fi ed in the BMP manual on Water Supply (APA 1985c),are
expected to avoid impacts to Jack Long Creek from uncontrolled
runoff from the camp area.Re!sidual increases in sediment
1 evels are not expected to adve'rsely affect spawning habitats
in Jack Long Creek or the unnamed creek nearby.
Fuel and Hazardous Materials
Impacts associ ated wi th the hancil i ng and storage of fuel and
hazardous materials were described 'in Section 3.1.1(b).The
BMP manual on Fuel and Hazardous Materials (APA 1985e)will be
fo 11 owed to avoi d adverse impacts on the aquatic organ isms in
Jack Long Creek and other nearby waterbod i es.The BMP Oil
Spill Contingency Planning manua'l (APA 1985f)will be utilized
to avoid or contain accidental pe:troleum spills.
(Vii)Blasting
Construction of the arch dam and the saddle dam will require
excavation in the dewatered river channel at the damsite.The
ADF&G blasting gUidelines (Table 9)will be applied.
94
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-
.....
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.....
(viii)
Excavation by blasting or by mechanical means may result in the
introduction of materials into the Susitna River that would be
carried downstream.However,the cofferdams are expected to
contain sediment laden water with the site until treated.It
is unlikely that the damsite itself is located in a stretch of
the Susitna regularly inhabited by fish;therefore,it is
expected that the excavation Clnd blasting required at the
damsite would not disrupt fish populations.
Recreational Imoacts
As with the Watana dam,the most signi ficant long-term impact
associ ated wi th the Devi 1 Canyon dam wi 11 be the increase in
fi shi ng pressure.The camp and vi 11 age at the Devil Canyon
site will house a maximum of 1900 workers for several years.
As a resul t of the improved a.ccess and hi gher popul at ion,
streams and lakes in the vicinity will be subjected to
increased fi shi ng pressure as d;escri bed inSection 2.1.1 (b).
This area has not been heavily utilized for sport fishing in
the past.
The habitats most 1 ikely to be affected by increased fishing
i ncl ude Cheechako Creek,unnamed creeks and 1 akes,Jack Long
Creek,and to a lesser extent,the Susitna River and Portage
Creek,which enters the Susitna River on the opposite side of
the Susitna River about 2.5 mil es (4 km)downstream from the
dam location.Cheechako Creek,Jack Long Creek and the unnamed
creeks and lakes support relatl1vely minor fish populations,
however,Portage Creek is one of the major clearwater
tributaries of the middle reach of the Susitna River and
supports significant runs of chum,pink,chinook and coho
salmon (Barrett et al.1984,1985).Resident species in
Portage Creek include rainbow trout,Arctic grayling,Dolly
Varden,and round whitefish (Schmidt et al.1984,Jennings
1985).In the Portage Creek drainage,sportfishing for rainbow
trout,coho salmon,Arctic gra.yling,and Dolly Varden is
95
....
primarily concentrated at the tri butary mouth.Rai nbow trout
appear to be particularly susceptible to sportfishing in the
fall when they are concentrated at the mouths of tributaries
(Schmidt et al.1984).Access to Portage Creek from the
construction area will be difficult and dangerous because of
the steep side slopes and any increase in fishing pressure by
construction workers is expected to be minimal.
3.1.3 -Stage III:Watana Dam and Facilities
Construction during Stage III will take place at the Watana damsite
established in Stage I.The dam crest elevation will be raised and the
generating power will be increased from Stage I.Section 3.1.1(a)
details the Stage I dam and facilities.
(a)Description
During Stage III,the Watana dam will be raised to a crest elevation
of 2205 ft (672 m)(Figure 19).The maximum normal reservoir
elevation will be increased to 2185 ft (666 m).The minimum
operating level of the reservoir will be 2065 ft (630 m).The
concrete spillway,outlet facility structure and the two power
intakes will be raised.A third power intake and two additional
power generating units will be constructed.Upon completion of the
Stage III development,the dam will be approximately 0.75 mile (1.3
km)wide,0.75 (1.3 km)mile long and 885 ft (267 m)high.Over 62
million cubic yards (47,500,000 m3 )of material will be used to
construct the dam.
Excavation of 1 million cubic yards (0.75 million m3 )of gravel
material will be ~eeded for the Stage III development of the Watana
dam.The upstream regions of Borrow Site E (Figure 19)are not
expected to be inundated by the Devil Canyon reservoir,which has a
normal operating elevation of 1455 ft (443 m)to 1405 ft (428 m),
with the drawdown occurring from June to August.Additional gravel
materi al in the downstream area of the borrow site wi 11 be exposed
96
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--
during drawdown and will be available for excavation during
construction of the Stage III Watana dam.Excavation to remove the
needed amounts of material may necHssitate the use of cofferdam
structures and/or dragline operations"Excavation will increase the
turbidity and suspended sediment concE!ntrations in the rehabilitated
lake.The lake will be temporaril~y isolated from the mainstem
during borrow activities to avoid increasing the turbidity and
suspended sediment levels in the Susitna River ..The site will be
rehabilitated after the termination of excavations.
The construct i on campsite from Stage ][wi 11 be reused for Stage II 1.
A maximum population of 2000 people is expected.A d~scription of
the camp is contained in Section 3.1.1l(a).
The facil it i es establ i shed duri ng Stage I for water removal and
waste handling (Section 3.1.1(a»will be utilized during Stage III
construction.
(b)Potential Impacts
Potential impacts from Stage III construction will be similar to
potential impacts identified for Stage I (Section 3.1.1(b».The
predomi nant effect of constructi on duri ng Stage I II wi 11 be the
increase in duration of potential impclcts from fill placement,water
remova 1,and waste management (Sec:t ion 3.1.1 (b».The 1onger
duration of these potential impacts i$not expected to significantly
degrade the aquatic resources of thE!region.Additional impacts,
such as the impact from the gravel material excavations at Borrow
Site E and the clearing of the reservoir area to a higher level,are
discussed further.
(i)Borrow Activities
Ouri ng the Stage II I development of Borrow Site E,temporary
increases in suspended sediment levels and instream
disturbances may cause fish to avoid habitat in the vicinity of
97
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the mouth of Tsusena Creek.The additional gravel excavations,
even though conducted in accorda,nce with the BMPM (APA 1985b)
and the USFWS Gravel Removal Gu·idel ines (Joyce et al.1980b),
may increase suspended sed i ment 1eve 1sin the Dev il Canyon
reservoir;relative to the expected reservoir turbidities,the
sediment contribution is not explected to signi fi cantly degrade
the water quality.Borrow activities may temporarily disturb
fish util izing habitat at the mouth of Tsusena Creek.The
sites of gravel excavation will be rehabilitated following the
cessation of material removal.
(ii)Liquid and Solid Waste Management~
Construction wastewater will be treated and neutralized prior
to discharge into the Susitna IRiver upstream from the Devil
Canyon reservo i r.The eff'}uent quant it i es will .be
insignificant relative to the reservoir volume water quality
degradation in the Devil Canyon impoundment is not expected to
be significant.
Wastewater from the construct i em camp and vi 11 age wi 11 be
discharged through the system established during Stage I
(Section 3.1.1(a»;however,the effluent outlet will be
inundated as the Stage III Watana dam becomes operational.The
effluent is not expected to si!~nificantly degrade the water
quality in the Stage III Watana Reservoir due to the small
amount of discharge and the rapid mixing which will be caused
by the flow of Deadman Creek i ntol the reservoi r.
(iii)Disposal Sites
During the Stage III development of the Watana dam,overburden,
vegetation and unusable materia"11 from the dam site will be
stockpiled until disposal in the specified disposal area on the
north bank of the Susitna River (Figure 15).Disposal will
take place during the drawdown cycle of the Stage I reservoir;
98
the reservoir will reach a minimum normal elevation of 1850 ft
(564 m)approximately in April.Quantities of disposal
material for the Stage III dE~velopment will be less than
quantities from the Stage I dlevelopment.Residual aquatic
impacts are not expected if activities ·conform to the BMPM on
Erosion and Sedimentation Contro"'(APA 1985b).
(i v)Clearing
increased reservoir
similar to those
will remove trees bl~l ow the
Potent i ali mpacts wi 11 be
Section 3.1.1{b).
Clearing
elevation.
discussed in
3.2 -Construction Zone Mitigation
.-
Mitigation of potential impacts associated with the construction of the Watana
and Devil Canyon dams and facilities will be achieved primarily by adherence
to the BMPM construction practices.The BMP described in the Erosion &
Sedimentation Control Manual (APA 1985b)will be followed to minimize
turbi dity and sil tati on impacts.The BMP manual on Water Supply (APA 1985<:)
will be utilized to minimize impacts associated with water withdrawal.
Activities involving wastewater,petroleum products and hazardous materials
will conform to the relevant BMPM (APA 1985d,1985e,1985f)to avoid or
minimize potential "impacts on the aquatic reSOUl"ces in the vicinity.
-
Potential impacts are identified in Section 3.1.Section 3.2.1 contains a
discussion of the impact mechanisms and the mitigation measures that will be
appl ied during and after construction.Those mechanisms considered to have
the greatest potential for adverse impact to the aquatic environment are
discussed first.Avoidance,minimization,rectification and reduction of
impacts are discussed.Costs associated with the rehabilitation of Borrow
Site E are presented in Table 8;no other dire:ct mitigation costs have been
evaluated as adherence to the BMPM (APA 1985b,1985c,1985d,1985e,1985f)is
the primary means of mitigation.
r 99
--
Continued monitoring of the construction facilities and activities will ensure
that impacts to the aquatic environment are avoided or minimized.Monitoring
can identify areas that may need rehabilitation or maintenance and areas where
previous mitigation measures are proved inade!quate and remedial action is
necessary.Moni tori ng of constructi on is di sClIssed inSect ion 3.2.2.Costs
associated with construction monitoring are outlined in Table S.
3.2.1 Impact Mechanisms and Mitigation Measures
(a)Borrow Sites
-
(i)
(i i )
Impact Mechanism
Remova 1 of fl oodp 1ain gravel at Borrow Si tes E,G and other
potential sites (Figures 10 and 17)can cause increases in
erosion,siltation,turbidity,ice buildup caused by ground
water overflow,fish entrapment,and alteration of fish
habitat.
Mitigation
Gravel removal in the floodplains of the Susitna River will be
conducted in accordance .wi th the USFWS Grave 1 Removal
gUidel ines (Joyce et al.19S0b)and the BMPM on Erosion and
Sedimentation (APA 19S5b).Buffers will be retained between
the sites and any active chanm!ls.The natural or man-made
buffers will consist of vegetated stripsand/or dikes designed
to prevent erosion and subsequent increases in turbidity.At
Tsusena Creek,buffers will be maintained between the channel
and the excavation.Cheechako Creek will be diverted around
the borrow excavation.Fish passag~will be maintained through
Tsusena,Cheechako and all other fish supporting creeks
affected by borrow activities.The borrow areas will be
subdivided into aliquots;each aliquot will be cleared and
excavated prior to the commencement of borrow activities in
adjacent aliquots.Rehabilitation of the disturbed aliquot
100
wi 11 proceed concurrently wi th borrow act i vi ties in
ali quots.Rapi d rehabil i tat ion wil 1 ass i st in
erosional impacts to the aquatic resources.
adjacent
reducing
..,..
~'
Material washing operations will use recycled water and will
not discharge into adjacentcl earwater streams.Water
containing suspended sediments will be circulated through
settling ponds and reused.Settlling ponds may be maintained by
dredging fine materials which will be removed from the
floodplain and used in site rElhabilitation.Settling ponds
will be cleared when theeffl uent approaches the ADEC/USEPA
standards.Upon closure of the borrow site,the water will be
discharged from the settling ponds into the Susitna River.All
effl uents wi 11 conform to ADEC/IJSEPA standards (AS 46.03.100;
18 AAC 70.020;18 AAC 72.010).
Overburden and unsuitable material will be stockpiled for
return to the removal area for contouring and revegation
efforts.Material will be stockpiled outside the floodplain to
avoid impounding flow at higher stages which would result in
material erosion.If insufficie!nt space exists away fr,om the
floodplain,material stockpiled within the floodplain will be
armored to prevent erosion.
Rehabilitation at Tsusena Creek will proceed both concurrently
with borrow activities and following closure of the site.
Stockpiled overburden will be returned to upland aliquots.
Exposed slopes wil 1 be stabil i ZE!d and contoured to bl end wi th
surrounding features and topography.Revegetation and
fertilization of the disturbed areas will assist in minimizing
erosion.All man-made objects 'rlill be removed following site
closure.Settling ponds will be dewatered of the clear surface
water and silt will be broadcast,removed ,to approved disposal
sites,left in place with a riprap covering or piled in the
nonflooded sections of the site.
101
(b)
(i)
The pit excavation at Borrow Site E will be rehabilitated to
provide fish habitat.A rehabilitated borrow pit can provide
fish rearing and overwintering and increase the availability of
Arctic gray1 ing and Dolly Varde"l (Joyce et a1.19aOa).Spoil
materials will be used to provide a diversity of water depths
and bank slopes to create a varliety of fish habitats.A mean
depth of a ft (2.5 m)or greater will be needed to assure
survival of overwintering fish.The pit will have a relatively
long and narrow shape with an irregular shoreline aligned
longitudinally in the floodplain.
Spoi 1 and overburden will be used to construct i sl ands and
peni nsul as.An out1 et channe'l will be provi ded at the
downstream end of the pit to enab1 e fi sh movement between the
mainstem and the pit.The unna.med creek will flow directly
into the pit and contribute nutrients to improve the quality of
the fish habitat within the pit.Tsusena Creek will remain
independent of the pit as a result of the buffer between the
excavation and the active channel of the creek.Figure 22
depicts a rehabilitated pit excavation that may be appropriate
for Tsusena Creek.
Borrow site G will be inundated following dam completion;
rehabilitation will consist of stabilizing slopes to minimize
eros i on.and removi ng man -made objects.Revegetat i on wi 11 not
be necess ary .Sett1 i ng pond s wi 11 not be dewatered but will be
stabilized to prevent fine sediment influxes to the reservoir.
Water Quality
Impact Mechanism
Temporary degradations in water qual ity caused by increased
turbidity,sedimentation and petroleum contamination may change
the speci es compos it i on and reduce the product i vity of the
system (Bell 1973,Alyeska Pipeline Service Company 1974).
102
-
REHABILITATED BORROW SITE E
AL.ASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 22
103
ENTR:IX,INC.
HARZA·EBASCO
SUSITNA JOINT VENTURE
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Di scharge of camp effl uents may result in increased nutri ent
loading.Concrete batching plants produce highly alkaline
effluents.Wastewater may have a higher temperature than
natural waters.
(ii)Mitigation
The primary mitigation measures that will be used to minimize
degradations in water quality are:(1)employing BMPM erosion
control measures including runoff control,stilling basins and
revegetation (APA 1985b);and (2)maintaining vegetated buffer
zones.
Disposal sites will be constructed so that neither runoff
during breakup nor rainfall will wash silty material into
streams.This may entail runoff control structures,
,surround i ng the di sposa 1 site wi th berms,or channel i ng runoff
through containment ponds.Prior to site inundation,the
overburden and slash will be stalbil i zed wi th gravel or ri prap
fill.Turbidity increases,water quality degradations,and
other impacts are not expected due to disposal site inundation
(Sect ion 3.1.1)•
Natural vegetation is a major factor in preventing erosion
(Alyeska Pipeline Service Company 1974).Clearing will be
confined to the minimum area amd level necessary.Cleared
material will be removed to approved disposal sites,salvaged,
or burned onsite.Revegetati on of cl eared areas wi 11 proceed
as rapidly as possible following the termination of
construction activities.
All wastewater will be treated to comply with ADEC/USEPA
effluent standards (AS 46.03.100;18 AAC 70.020;18 AAC
72.010).The concrete batch i ng effl uent will be neutral i zed
and treated prior to discharge into the
104
Susitna River to avoid impacts related to pH and toxic
substances.Secondary treatment will be utilized to reduce the
concentration of suspended solids:and biochemical oxygen.demand
(BOD)of the wastewater.The effluent will retain relatively
high concentrations of nitrogen and phosphorus.Wastewater
will be retained in settling ponds until effluent temperatures
approximate instream temperatures.
(c)Susitna River Diversions
(i)Impact Mechanism
The diversion tunnels and the dams will act as barriers to
successful fish migration.Chinook salmon will not be able to
able to util ize spawning habit(lt upstream of the dam site.
Fish passing downstream through the diversion tunnels are
expected to be lost because of abrasi on from tunnel wall s.
During summer,relatively few fish are present in the vicinity
of the tunnel entrance.During winter,resident fish are
expected to be entrained into the intake and passed downstream.
(ii)Mitigation
The loss of aquatic habi tat caused by the i nsta 11 at i on of the
dams and diversion tunnels will be included in the compensation
for lost reservoir habitat that will take the form of acquiring
publ ic access and undertaking ha,bitat improvement outside the
project area (Entrix 1985).
(d)Oil and Hazardous Material Spills
(i)Impact Mechanism
Spill s of oil and other hazardous substances i ntostreams are
toxic to fish and their food organisms.
105
(ii)Mitigation
Mitigation for oil and hazardous material spills is described
in Section 2.2.1 and will be conducted in accordance with the
BMPM on Oil Spill Contingency Planning (APA 1985f);if an
unavoided major oil spill occurs,compensation will be
determined following consultation with the resource management
agencies.
(e)Clearing the Impoundment Area
(i)Impact Mechanism
Impoundment area clearing may
contributions to the Susitna River.
(ii)Mitigation
accelerate eros i ona 1
~,
Clearing will be scheduled annually as close to reservoir
fill i ng as is feas ib1e.Vegetat i on wi 11 be cleared to the
elevation of the high water level anticipated for each year of
fill i ng.Oi sturbance to the vegetative mat wi 11 be avoi ded.
Erosion control methods described in the BMP manual on Erosion
and Sedimentation Control (APA 1985a)will be employed wherever
needed to minimize erosion.No additional mitigation will be
required.
(f)Increased Fishing Pressure
(i)Impact Mechanism
The sport fishing pressure on the local streams and lakes will
increase due to the presence of the construction workers.
106
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-
(ii)Mitigation
The mitigation of the aquatic impact from increased fishing
pressure has been previously discussed in Section 2.2.1.
Additional mitigation is not expected.
3.2.2 -Monitoring
Monitoring is recognized as an essential project mitigation feature that
will provide for a reduction of impacts over time.Monitoring will be
conducted throughout project construction:
To assure that the environmentally careful construction practices
detailed in the BMPM's (APA 1985b,1985c,1985d,1985e,1985f)are
being employed on the project to avoid or minimize impacts;
To verify and evaluate the effectiveness of the operation and
maintenance of mitigation features;and
To recommend changes in construction practices or mitigation
features to further avoid,minimize,or reduce impacts.
Construction monitoring will consist of monitoring construction
activities to verify that proper construction practices are being
followed and that project facilities are being properly maintained.This
monitoring activity will cover all project facilities,including camp and
village construction,material removal,washing operations for dam
construction,reservoir clearing,abandonment,and rehabilitation
activities.
As described in Section 2.2.2,the APA will assign at least one member of
its staff to be an Environmental Field Officer (EFO)respons"ible for
compl i ance wi th regul atory requi rements and permi ts.Duri ng and after
construction activities,the EFO will review the designs and verify that
the activity is in compliance with the BMPM's permit and license
stipulations.If a discrepancy with existing stipulations is observed
107
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.....
-I
.....
and if a variance was not requested prior to implementing the activity,a
certificate of non-compliance will be issUied and all responsible parties
will be notified.
The.monitoring program will include water quality and borrow site
monitoring.Deadman Creek will be monitored to detect degradations in
water quality from increased phosphorous or nitrogen (Harza-Ebasco
1985a).The water quality monitoring program will also investigate
dissolved oxygen levels downstream of the effluent outlet (Harza-Ebasco
1985a).Borrow sites will be monitored during construction and after
rehabilitation to assure that water quality is not being significantly
degraded by sediment contributions.Settling pond effluents will be
monitored to assure compl i ance with ADEC/USEPA standards.Tsusena and
Cheechako creeks will be monitored for fish blockages.Following
rehabilitation,Tsusena Creek will be monitored to ensure that grading,
revegetation and other mitigative measUires are successful.Impacts
identified through the monitoring program will be assessed and rectified
following consultation with the resource agencies.
108
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.-'
4.0 TRANSMISSION LINES
Power generated at the Watana dam and the Devi 1 Canyon dam will be del ivered
to power utilization regions by transmission lines.Construction will occur
throughout the three stages of development (Figlure 23).Table 10 depicts the
transmission line construction planned for each stage.The transmission lines
will be bu 11 t from the Watana dam along the access road to the Devil Canyon
dam site and continue along the railroad spur from Gold Creek (Figure 24).At
Gold Creek,the transmission lines are planned to converge with the Anchorage-
Fairbanks Intertie currently extending from Willow to Healy (Figures 25,26
and 27).The route south of Willow will be extended to Point MacKenzie where
a submari ne cabl e wi 11 cross the Kni k Arm.The termi nus of the southern
section will be the University substation in Anchorage (Figure 28).The
northern section will be extended from Healy to Ester near Fairbanks (Figures
29 and 30).The transmission corridor from Anchorage to Fairbanks will be 330
miles (530 km)long.
Potential aquatic impacts associated with the transmission line construction
and maintenance will be similar to those identified for the access corridor
(Section 2.1).In general,impacts are anticipated to be short in duration
and confined to the construction phase.Short-term aquatic impacts will occur
where the transmission lines cross resident and anadromous fish streams.The
transmission line corridor will increase the accessibility of these streams
and nearby lakes and may lead to increased fishing pressure;this long-term
impact is probably the most significant potenti al aquati c impact associ ated
with transmission line construction.
Mitigation of potential transmission line impacts will also be similar to the
mitigation of the access road impacts (Section ~~.2).Mitigation of short-term
potential impacts during construction will be accomplished primarily by
adherence to the construction practices presented in the APA BMP manuals (APA
1985b,1985c,1985d,1985e,1985f).Mitigation of impacts resulting from
increased accessibility may include restricting usage of any maintenance
roads .
109
1 I,t,-1 I c),l l t,I ~--l 1
___EXISTING INTERTIE
rllllll~WATANA INITIAL DAM
,__•DEVIL CANYON
•••••••••••,WATANA HIGH DAM
HEALY
=-_-_.,.....~DEVIL CANYON
-"JII••'.',",'I"'I",A~IJlIIII'IIII"IIIIIc.JJ.WATANA
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GOLD CREEK
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KNIK ARM ~ANCHORAGE
STAGED CONSTRUCTION OF TRANSMISSION LINES
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Figure 23 ENTRIX,INC.
HARZA-EBASCO
SUSITNA JOINT VENTURE
_.
~:z z "'S4¥{:c:sa •
Table 10.Numbers of 345 kV circuits to be installed during staged construction
of the transmission lines.
-,
Segment of transmission line
Fbks.Healy Devil Gold Willow
Construction to to Watana tOI Canyon to Cr.to to
Stages Initiated Healy Gold Cr.Devil Canyon Gold Cr.Willow Anchorage
Stage I 1995 1 2 2 1 2
Stage II 1998 1 1 2 1
Stage III 2006 1 1
.-.
-,n
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111
1 -1 1,;}}J \1
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TRANSMISSION LINE
SCALE :t ,.It.-iS
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CAMP SITE
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TRANSMISSION LINE CORRIDOR FROM THE WATANA DAM
SITE TO GOLD CREEK
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
Reference:APA 1985j.
Figure 24 ENTRIX,INC.HAAZA-EBASCO
SUSITNA JOINT VENTURE
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
HARZA-EBASCO
SUS1TNA JOINT VENTURE
LEGEND
o 1 2
MILES l::::::t:::::::
-t+++t+ALASKARAILROAD
STREAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
THE SOUTHERN SECTION OF THE
ANCHORAGE-FAIRBANKS INTERTIE
ENTRax,INC.
/
SOUTH FOIlt(
MATCH LINE FIGURE 26
DOUGLAS SUBSTATION
~NE FIGURE 2B
WILLOW
Figure 25.,.-
113
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
.LEGEND
-++++++ALASKA RAILROAD
STREAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
THIE CENTRAL SECTION OF THE
ANCHORAGE-FAIRBANKS INTERTIE
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Figure 26
ENTRIX,INC.
HARZA·EBASCO
SUSITNA JOINT VENTURE
114
LEGEND
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MATCH LINE FIGURE 26
/
115
HARZA-EBASCO
sus I T N A J 0 I N T V E N T U REFigure 27
-t+t+++ALASKA RAILROAD
STREAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
THE NORTHERN SECTION OF THE
ANCHORAGE-FAIRBANKS INTERTIE
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
MATCH LINE FIGURE 29
ENTRIX,INC.
-
._-------~--------_.__.'"-----------------------
-
WILLOW Q 1
MILES Ci
STREAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
ANCHORAGE
Figure 28
W/UOW CREEK---------
HARZA·EBASCO
SUSITNA JOINT VENTURE
/
/
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.
THE TRANSMISSION LINE CORRIDOR ...
FROM ANCHORAGE TO WILLOW
-
116
---------------
THE SOUTHERN SEC:TION OF THE TRANSMISSION LINE
FROM tiEAlY TO ESTER
o 1
C::J.IIILIS
HARZA·EBASCO
SUSITNA JOINT VENTURE
\.EGEND
AlASKA RAI\.ROAO
STAEAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
Al.ASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
ENTRIX,INC.
MATCH LINE FIGURE 30
Figure 29
HEALY
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117
--o 1
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.....
-++++++ALASKA RAILROAD
STREAMS
PARKS HIGHWAY
TRANSMISSION LINE CORRIDOR
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
THE NORTHERN SECTION OF THE TRANSMISSION LINE
FROM HEJ~LY TO ESTER
,..,
,,
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Figure 30 ENTRIX,liNe.
HARZA-EBASCO
SUSITNA JOINT VENTURE
118
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4.1 -Impact Analysis
4.1.1 -Watana to Gold Creek
(a)Description
From the Watana dam site to Gold Creek,a distance of 37 miles (60
km),two parallel sets of towers ~,i1l be built during Stage I
construction;the towers will require a 285 foot (87 m)wide
right-of-way through tundra and occasionally dense vegetation.The
transmission lines will consist of a series of steel towers
approximately 1300 ft (393 m)apart (J\PA 1985a).The towers will be
x-framed guy towers,capable of supporting three conductors.The
transmission towers will be spaced so that structures are not
located within currently active stream channels and are removed from
floodplains to the best extent practicable.The transmission line
corridor is sited within 1 mile (1.6 km)of the Devil Canyon access
road except near the Watana dam.
In the right-of-way,trees and shrubs within 20 ft (6 m)of the
conductors and trees within 55 ft (16.5 m)of the tower centerline
will be cl eared as well as any other trees or shrubs that may hamper
construction or pose a threat to the completed line.The selective
clearing w"ill retain low shrubs and grasses in order to minimize
erosion.Revegetation in the corridor will be allowed to proceed so
long as the i ntegri ty of the 1i nes is not end angered and veh ic1es
are able to follow the cleared area associated with the lines.
Where vegetation is dense between the Susitna River crossing and
Gold Creek,cleared vegetation will be hauled to a designated area
and salvaged or burned.Deciduous v\egetation may be piled at the
corridor margins;coniferous slash may be chopped with a hydro-axe
and broadcast in the corridor.Piled coniferous vegetation will be
burned within the first year after cutting.Clearing activities are
scheduled to occur from 1995 to 1998 (Figure 6).
119
,~
-
,....,
-
-
-
The transmission line construction wi"ll necessitate stream crossings
by heavy equi pment such as hydro-axes and drill ri gs.Streams and
lakes potentially impacted are previously identified in Sections
2.1.2 and 2.1.4 since the transm'ission corridor will closely
para11 e 1 the Devil Canyon dam access road and the railroad spur
connecting Devil Canyon to Gold Creek (Figure 24).Temporary
bridges may be installed depending on the stream size and passage
requirements.For small streams with low gradients and gradual
banks,low water crossings may be used.All crossings will be
designed to provide adequate fish passage (Harza-Ebasco 1985b).
The towers will be supported by a variety of foundations designed
for soil conditions at each site.Driven steel pilings and steel
grillage foundations will be preferentially utilized although
cast-in-place concrete piles will occasionally be necessary.Rock
footings will employ grouted rock anchors with a minimum use of
concrete to facilitate winter construc:tion.Buffers of at least 100
ft (30 m)between active stream channel s and the sites of driven
piles will be retained to avoid·increased sedimentation from soil
vibration in the channel during pile driving.Waste concrete will
be disposed at designated sites ~~ay from streams and lakes.
Concrete batch water will be neutralized prior to discharge.
Foundation sites will be graded following construction to contour
the disturbed surface to suit the existing grades.
Ground access will be provided in transmission line corridors for
peri od ic rna i ntenance and repa ir of "I i nes,towers and conductors.
Within the transmission line corridor,a 25 ft (7.5 m)wide trail
will be cleared;the trail will be suitable for flat tread,balloon
tire vehicles.The maintenance trail will remain clear of
vegetat i on and will be accessed us i ng secondary trails from the
Devil Canyon access road and rail road.St ream cross i ngs in the
corridor will be minimized by cleal"ing secondary trails to the
sections of the corridor trail separated by major streams.
Vegetation or man-made buffers betweE!n the corridor trail and the
stream will discourage stream crossings.Along the Watana to Gold
120
Creek corridor,a secondary trail
road or railroad access corridor.
maintained by the APA.
(b)Potential Impacts
wi 11 connect each tower to the
The secondary trails will not be
Potential aquatic impacts from Stage I construction of the
transmission line from Watana to Gold Creek are similar to those of
the Dev il Canyon access road (Sect ioIII 2.1.2)and the ra il road spur
(Section 2.1.4).Impacts discussed in these sections are generally
applicable to transmission line construction.Variations or
alterations in impacts are discussed further.
-
-
.....
(i)
(ii)
Clearing
Residual impacts from transmission line clearing from the
Watana dam site to Gold Creek will include minor water quality
degradations from erQsion incl!'eases and small amounts of
aquatic habitat loss from cover removal.At transmission line
stream crossings,clearing may remove overhanging vegetation·
that provides cover for fi sh.Fi sh may not utili ze the
available habitat if cover is not available.This habitat loss
is expected to be temporary and minor relative to the total
amount of available habitat.BMPM techniques (APA 1985b)will
be followed at cleared vegetation stockpiling,salvaging or
burn i ng sites to prevent surface runoff from cont r"j but i ng ash
or organic materials to streams and lakes as described in
sections 2.1.2(b)and 2.1.4(b).
Stream Crossings and Encroachments
Instream activities will be limited to the installation of
necessary stream crossing structures designed to provide
adequate fi sh passage (Harza-Ebasco 1985b).Stream crossi ngs
at major fish supporting streams will be avoided by utilizing
the alternative access secondary trails from the access road
121
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,....
"'""
-
and railroad to Devil Canyon.Instream use of equipment will
be required to be short in duration and will be scheduled to
avoid environmentally sensitive periods for the designated
streams (Figures 9 and 14).Residual impacts from stream
crossings consist of temporary habitat losses,which are not
believed to be of significant magnitude to require mitigation.
Mitigation for a major petroleum spill is presented in Section
2.2.1.
(iii)Operation and Maintenance Activities
Significant aquatic impacts are not expected to occur during
operation and maintenance activities.Some local ized habitat
disruptions could occur when maintenance vehicles need to cross
wetlands and streams to repa<ir damaged lines or towers.
Streams may be forded to make re~pairs if the temporary bridges
or culverts are removed after construction is complete.
Aquatic habitat in the immediate vicinity of the crossing could
be affected.In addition,there may be increases in suspended
sediments and sedimentation in downstream reaches.However,
maintenance activities in remote areas are expected to utilize
helicopter transportation.
,
In the longer term,the transmission line corridor and
maintenance road may increase fishing pressure on lakes and
streams in the vi cinity.Because the vegetation w'il 1 be kept
relatively low,hikers and all terrain vehicles will be able to
use the transmission corridor ,as a trail.In winter,snow
machines will also be able to traverse these cleared areas.
Between Watana and Devil Canyon,access may be increased
marginally beyond that provided by the nearby Devil Canyon
access road.The corridor and maintenance track between Devil
Canyon and Gold Creek paralleling the railroad spur would
marginally improve access to tributaries and sloughs of the
Susitna River and may slightly increase the fishing pressure on
these habitats.
122
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4.1.2 Devil Canyon to Gold Creek
(a)Description
The Stage II construction on the DElvil Canyon dam will add two
transmission lines to the transmission corridor from Devil Canyon to
Gold Creek.This will result in an arrangement of four parallel
sets of towers extending .for 8 miles (13 km)along this segment of
the lines.The corridor will be widened to 510 ft (153 m).
Additional clearing along the corridor will be necessary as
described in Section 4.1.1.
(b)Potential Impacts
The potential impacts associated with installing two additional
transmission lines in the Devil Canyon to Gold Creek corridor will
be similar but of less magnitude than the impacts identified in
Section 4.1.1.Disposal sites from Stage I clearing will be
utilized.Significant new impacts are not expected with this
incrementa,l addition.
4.1.3 Willow to Healy
(a)Description
The transmission lines will join the Anchorage-Fairbanks Intertie at
Gold Creek.The Anchorage-Fairbanks Intertie,which connects Willow
to Healy was compl eted in 1984 (Figures 25,26 and 27).Ouri ng
Stage I construction,the Susitna Hydroelectric Project will add
another line of towers from Gold Creek to Willow within the same
right-of-way;the Stage II Devil Canyon construction will include
building an additional transmission line in the Intertie corridor
from Gold Creek to Healy.A third transmission line will be
constructed from Gold Creek to Willow to transport power following
Stage III development at Watana (Figure 23).The Intertie corridor
for the Stage III development will be cleared to a width of 300 ft
123
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"~
,jIlIOIIiIl
(90 m)from Gold Creek to Healy and 400 ft (120 m)from Gol d Creek
to Willow.The impacts will be similar to those experienced during
Intertie construction.The Environmental Assessment Report for the
Intertie (Commonwealth et al.19182)discusses the expected
envi ronmenta 1 effects of transmi ss ion 1i ne construct ion in th is
segment.Fi sh streams that will be crossed i ncl ude the Nenana
River,Talkeetna River,Chunila Creek,Susitna River,and the
Kashwitna River.A total of 77 streams will be crossed (Table 11).
The majority of streams crossed by the transmission lines along the
Intertie route are utilized througholUt the year by anadromous and
resident species (Table 11).Anadromous fish include chinook,
sockeye,coho,pink,and chum salmon;resident species of primary
importance include Arctic grayling,Dolly Varden and rainbow trout.
Construction will proceed in a similar manner to the construction of
the Intertie transmission lines.Experience gained from the
previous construction will be applied and is likely to result in a
shortened construction period.Access established during
construction 'of the Intertie will likely be utilized.During
construction,heavy equipment will Clross small streams.Temporary
bridges or culverts may be installed to minimize impacts to aquatic
organisms.The majority of stream crossings will utilize log
stri nger and temporary bridges.Small headwater streams wi thout
fi sh popu1 at ions will be forded.These streams are i dent ifi ed in
Tab1 e 11 and are located at the approximate mil e post (AMP)79,
90.5,91.5,92.5,94,117.5 and 137.5 as measured from the Willow
substation.Large streams in the transmission corridor will not be
crossed by equipment;sections of the transmission line separated by
major streams and ri vers will be accessed from exi st i ng roads such
as the Parks Hi ghway.Construction where secondary roads to the
site would be long and involve numerous stream crossings will likely
utilize helicopter transportation in a similar manner to
construction along the Anchorage-Fairbanks Intertie.
124
Table 11.Streams crossed by the Anchorage-Fairbanks Intertie.
Stream
Approximate miles from
Willow Substation SpeC1E!S Present
Willow Creek .4 Chinook,coho"chum,pink and sockeye salmon;
~Dolly Varden;rainb~w trout;Arctic grayling;
whitefish;(burbot)
Rogers Creek 2.5 (Arctic graylllng,rainbow trout,Dolly.-Varden,whitefish,burbot)
Iron Creek 4 (Arctic grayHng,rainbow irout,Dolly
Varden,whitefish,burbot)
Li ttl e W"j 11 ow 5 (Chinook,sockeye,chum,coho and pink
Creek salmon;whitefish;Arctic grtyling;rainbow
trout;Dolly Varden;burbot)
Unnamed creeks 7,8.5 (Arctic grayHng,rainbow irout,Dolly
Varden,whitefish,burbot)
196 Mile Creek 10 (Arctic grayHng,rainbow trout,Dolly
Varden,whitefish,burbot)
197 1/2 Mil e 11.5 (Arctic grayling,rainbow irout,Dolly
Creek Varden,whitefish,burbot)
Kashwitna River 13 Chinook,coho and chum salmon;(Arctic
grayling;rainbow irout;Dolly Varden;
whitefish;burbot)
Caswell Creek 16 Chinook salmon;(Arctic grayling;rainb~w
trout;Dolly Varden;whitefish;burbot)
Sheep Creek 17 Chinook,pink and chum salmon;(Arctic
grayling;rainbow irout;Dolly Varden;
whitefish;burbot)
Unnamed Creek 19.5 (Arctic graylling,rainbow irout,Dolly
Varden,whitefish,burbot)
Goose Creek 24 Chinook and pink salmon;(Arctic grayling;
rainbow 1trout;Dolly Varden;whitefish;
burbot)
125
Table 11 (continued)
Approximate miles from
Stream Willow Substation Species Present
Unnamed Creek 27.5 (Arctic grayling,rainbow trout,Dolly,-Varden,whitefish,burbot)
Montana Creek 30 Chinook,pink and chum salmon;(Arctic
grayling;rainbow trout;Dolly Varden;
whitefish;bUirbot)
Unnamed Creek 34 (Arctic grayling,rainbow trout,Dolly
Varden,whitefish,burbot)
Answer Creek 36.5 (Arctic grayling,rainbow trout,Dolly
..-Varden,whitefish,burbot)
!
-Unnamed Creek 41 (Arctic grayling,rainbow trout,Dolly
Varden,whitefish,burbot)
Talkeetna River 45 Chinook,socklaye,coho,pink and chum
salmon;(Arct'ic grayling,rainboy trout,
~Dolly Varden,whitefish,burbot)
Unnamed creeks 48,50.5 (Arctic grayling,rainbow trout,Dolly
Varden,whitefish,burbot)
Chunil na Creek 54.5 Chinook,coho!,pink and chum salmon;
(Arctic grayl'ing;rainbow trout;Dolly
Varden;whitefish;burbot)
Tributary of 63 (Chinook and c:oho salmon;Arctic grayling;
-'Chunilna Creek rainbow 1troutj Dolly Varden;whitefish;
burbot)
Lane Creek 63.5 (Arct ic grayl 'i ng,rainbow trout,Dolly.-Varden,whitefish)
Unnamed creeks 67,70 (Arct ic grayl'j ng,ra i nbow trout,Dolly
Varden,whitefish)
Sherman Creek 70.5 (Arctic grayling,rainbow trout,Dolly
Varden,whitefish)
Unnamed creeks 71.5,73 (Arctic grayl'ing,rainbow trout,Dolly
Varden,whitefish)
Gold Creek 76 Chinook,coho and pink salmon,Arctic
grayling,rainbow trout,Dolly Varden,
.....whitefish,sculpin
Unnamed Creek 79 none 2
i"""(Waterfall Creek)
126
Table 11 (continued)
Stream
Approximate miles from
Willow Substation Speci les Present
Unnamed Creek "80.5 Ch i nook sa 1mOln,sculpin
Susitna River 81 Chinook,sockeye,coho,pink and chum salmon;
Arctic grayling;Dolly Varden,whitefish,
longnose sucker,burbot,sculpin
Tributary of 86 (Arctic grayling,rainbow trout,Dolly
Indian River Varden,whitefish)
Indian River 87.5 Chinook,coho,pink and chum salmon;Arctic
grayling;Dolly Var1en;rainbow trout;
F""
(whitefish,burbot),
Unnamed Creek 90 (Arctic grayling,rainbow irout,Dolly
Varden,whitefish,burbot)
Pass Creek 90.5 none 2
Unnamed creeks 91.5,92.5,none 2
94
Granite Creek 94.5 (Arctic grayling,rainbow trout,Dolly
F""Vardeh,whitefish)
Hurricane Gulch 96 (Arctic grayling,rainbow trout,whitefish)l.
Little Honolulu 98.5 (Arctic grayling,rainbow trout,whitefish)l
Creek
Unnamed Creek·100 (Arctic grayling,rainbow trout,whitefish)l
Honolulu Creek 101.5 (Arct ic grayl'j ng,rainbow trout,whitefish)1,.,..
Antimony Creek 103.5 (Arctic grayl'jng,rainbow trout,whitefi sh)1
Unnamed Creek 105.5 (Arctic grayling,rainbow trout,whitefish)l
Hardage Creek 106 (Arctic grayling,rainbow trout,whitefish}l
East Fork 111.5 Sockeye,coho and chum salmon;(Arctic
Chul itna Ri ver grayling;rainbow trout;whitefish)
,....Fourth of July 114.5 (Arctic grayling,rainbow trout,whitefish}l
Creek
I"'"Unnamed Creek 117.5 none 2
Coal Creek 118 (Arctic grayling,rainbow trout,whitefish}l
r-
127
Table 11 (continued)
Stream
Approximate miles from
Willow Substation Spec i E!S Present
....
Middle Fork 120
Chulitna River
Unnamed creeks 122.5,125
Unnamed creeks 125.5,126.5,
128
Jack River 131.5
Unnamed creeks 133.5,134.5,
136.5
Sockeye,coho and chum salmon;(Arctic
grayling,rainbow trout,whitefish)
(Arctic grayl'ing,rainbow trout,whitefish)l
(Arctic grayl"ing,whitefish)l
(Arctic grayling,whitefish)l
(Arctic grayl'ing,whitefish)l
Slime Creek 141
Carlo Creek 145.5
Unnamed Creeks 159,162.5,
163.5,164.5,
165
Yanert Creek 154
Unnamed Creeks 155,156.5
Montana Creeks 158
Nenana River
Unnamed Creek
Copeland Creek
Healy Creek
137
137.5
168.5
172
Arctic grayling,whitefish,burbot,
northern pike,sculpin
none 2
(Arctic grayl'ing,whitefish)l
(Arct j c grayl'i ng,wh i tefi sh)1
(Arctic grayling,whitefish)l
(Arctic grayling,whitefish)l
(Arct ic grayli ng,wh i tefi sh)1
(Arctic grayling,whitefish)l
(Arctic grayl'ing,whitefish)l
(Arctic grayling,whitefish)l
1 (species)can be reasonably expected,but not verified
2 Steep contours probably preclude fish
Reference:ADF&G 1978 Fi sheri es Atl as.Vol umf~S I and I!.
128
(b)Potential Impacts
The potential impacts of constructing additional transmission lines
in the Anchorage-Fairbanks Intertie corridor are expected to be
similar,but of less significance than the impacts associated with
the original construction activit'ies.Impacts identified for
transmission line construction in Section 4.1.1 are applicable.
Additional site specific impacts are discussed further.
r
(i)
(ii)
Clearing
The additional clearing required for the installation of the
second and third transmission line will be conducted using BMPM
techniques (APA 1985b).Sites previously selected during
construction of the Intertie for vegetation broadcasting,
stockpiling and/or burning will be utilized.Residual impacts
are not expected if the BMPN (APA 1985b)techniques are
foll owed.
Stream Crossings and Encroachments
Access provided during Intertie Iconstruction will be used.Any
instream activities will follow BMPM gUidelines (APA 1985b)to
avoid significant increases in suspended sediments,
1-sedimentation,or petroleum contamination.Aquatic organisms
in nearby habitat w'j 11 be tempor,arily di sturbed.
(iii)Operation and Maintenance Activities
The operation and maintenance of additional transmission lines
in the Intertie corridor are not l'lkely to increase aquatic
impacts beyond the eXisting level of impact.
129
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4.1.4 Heal y to Ester
(a)Description
The transmission line corridor will be extended from Healy to Ester
(Fi gures 29 and 30)duri ng construct i on of the Stage I Watana dam.
A second transmission line will be added to transport power during
the Stage II de vel opment of the Devil Canyon dam.When the two
transmission lines are installed,the corridor will have a 285 ft
(87 m}width.The Nenana River will b~crossed 2.75 and 58.75 miles
(4.4km and 94.5 km)from the Healy substation.The line will turn
north after crossing Dry Creek a~AMP 4.75 and roughly parallel the
Parks Hi ghway for the greatest part of its 1ength.The 1i ne wi 11
end at the Ester Substation (AMP 94.25).Clearing and construction
wi 11 proceed as descri bed for the Watana to Gold Creek sect ion
(Section 4.1.1).The streams crossed by the northern leg are listed
in Table 12.Streams of the Nenana Basin that are accessible and
have appropriate spawning habitat support spawning runs of resident
species such as Dolly Varden,round Ilihitefish and Arctic grayling.
A number of interconnected lakes lie in the Nenana Basin.Fish that
may be found in the lakes include Arctic grayling,whitefish,lake
trout,and burbot (ADF&G 1978).
(b)Potential Impacts
Impacts in the Healy to Ester segment will be similar to impacts
identified for the transmission line construction of other segments
(Section 4.1.1(b».Additional impacts specific to this segment of
the transmission line are discussed below.
-
""'"
(i )Clearing
Large amounts of cl ear;ng are not anti ci pated as much of the
vegetation is tundra.Cleared vegetation will be broadcast or
removed to selected sites and stockpiled or burned.Small
130
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Table 12.Streams to be crossed by the translnission line from Healy to
Ester.
"'.Approximate miles from
Stream Healy Substation
Nenana River 1.5
~AWl
Dry Creek 3
F""Panguingue Creek 6
Tributary to 15.5
Moose Creek
Moose Creek 16
Tributaries to 18.5,19.5,
Nenana River 21
Unnamed Creek 24
Windy Creek 30,32
Tributaries to 34.5,35.5,
Julius Creek 36,36.5,38.5
Fish Creek 41
,....
Little Panguingue
Creek
Slate Creek
Nenana River
Unnamed creeks
7.5
11.5
14.5
43,43.5,
45,46,46.5,
49,49.3,49.7,
50,50.5,51,51.5
131
Species Present
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
burlbot,chum and coho salmon
(Ar1ctic grayling,whitefish)1
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
scu'lpin
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
scu'l pin
(Arctic grayling,whitefish)1
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
burlbot,chum and coho salmon,
Incl:>nnu,northern pike
(Arctic 1grayling,whitefish,Dolly
Varden)
(Arctic 1grayl ing,whitefish,Dolly
Varden)
(Arl:tic 1grayl ing,whitefish,Dolly
Varden)
(Arctic 1grayling,whitefish,Dolly
Varden)
(Arc:tic grayling,whitefish,DjllY
Varden,burbot,northern pike)
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
scu"lpi n
Arctic grayling,round whitefish,
Dolly Varden,longnose sucker,
scu"1 pi n
(Arctic grayling,whitefish,Djlly
Varden,burbot,northern pike)
Table 12 (continued)
Little Goldstream 60.5
Creek
Tributary to Little 59
Goldstream Creek
Tributaries to 63,64.5,65.5
Goldstream Cr.66.5,68,68.2,
70
Little Goldstream 70.2
Creek
-
-
--
-
Stream
Tanana River
Unnamed creeks
Tributaries to
Bonanza Creek
Tributaries to
Ohio Creek
Tributary to
Alder Creek
Alder Creek
Emma Creek
Tributary to
Emma Creek
Ester Creek
Approximate miles from
Healy Substation
52.5
55,56
71,72,72.5
73
78,78.5,79
80.5,82,83.5,
84
87
88
89.5
90
93
Species Present
Chum,coho and chinook salmon,
Inconnu,northern pike,Arctic
grayling,whitefish,burbot
(Arctic 1grayling,whitefish,Dolly
Varden)
(Arl:tic 1grayl ing,whitefish,Dolly
Varden)
Arctic grayling,round whitefish,
Black fish,longnose sucker,
scu'lpin
(Arctic 1grayling,whitefish,Dolly
Varden)
Arctic grayling,round whitefish,
Black fish,longnose sucker,
scu'}pin
(Ar1ct ic1grayl i ng,whitefish,Dolly
Varden)
(Ar1:t ic1grayl i ng,whitefish,Dolly
Varden)
(Arlctic 1grayl i ng,whitefish,Dolly
Varden)
(Ar.:t ic1grayl i og,whitefi sh,Dolly
Varden)
(Arctic 1grayling,whitefish,Dolly
Varden)
(Arctic 1grayling,whitefish,Dolly
Varden)
(Arc:tic 1grayl ing,whitefish,Dolly
Varden)
1 (species)can be reasonably expected,but not verified
References:Letter from Jerry Hallberg (ADF&G Sportfish Div.)to
Nancy Heming (Falls Creek Environmental)October 29,1982.
ADF&G 1978 Fisheries Atlas.Volume II.
132
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....
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amounts of sediments,ash and other organic material may enter
streams or lakes.
(ii)Operation and Maintenance Activities
The corri dor from Heal y to Ester wi 11 fo 11 ow the route of the
Parks Highway;access wi 11 thelrefore be avail abl e previ ously
and the aquatic resources are not expected to be incrementally
impacted by the operation and rrriaintenance of the transmission
lines.
4.1.5 Willow to Anchorage
(a)Description
The transmission corridor from Willow to Anchorage (Figure 28)will
be established during the Stage I development of the Susitna
Hydroelectric Project.Th~Willow substation is located
approximately 0.5 miles (0.8 km)north of Willow Creek.Proceeding
fi rst west then south,the corridor wi 11 be routed between the
Susitna River and the Nancy Lake area,passing within 0.75 miles
(1.3 km)of the Sus i tna River.Thj~corri dor will cross several
SusitnaRiver tributaries,includif'ilg Fish Creek at AMP 18 as
measured from the Wi 11 ow substati on.Fi sh Creek contai ns chinook,
sockeye,pink and coho salmon,and rainbow trout.The little
Susitna with populations of chinook,coho,chum and pink salmon,
Dolly Varden,rainbow trout,Arctic grayling and probably whitefish
and burbot will be crossed at AMP 26.Few streams are crossed
between the Little Susitna River and the Knik Arm at AMP 44.The
Knik Arm,which is approximately 2.5 miles (4.1 km)wide at the
transmission line crossing,will be crossed by a submarine cable
system.The Kni k Arm swi tchi ng st«lt i on wi 11 be located between
Sixmile Creek and Eagle River.The transmission corridor will
bypass Otter Lake which is stocked with rainbow trout and cross the
Alaska Railroad and Fossil Creek.The corridor will parallel the
Glenn Highway for about 2 miles (3 km)before crossing Ship Creek at
133
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.....
AMP 75.Although Ship Creek supports;pink,chum,coho,sockeye and
chinook salmon,Dolly Varden and rainbow trout,the heavy
residential development in the vicinity has decreased the apparent
habitat quality.The corridors will traverse the Chugach Foothills
before terminating at the University substation near the corner of
Tudor and Muldoon roads.Table 13 presents a list of the streams to
be crossed by the transmission corridor.During Stage I
development,two transmission lines \11ill be constructed from Willow
to Anchorage (Section 4.1.1).A th'ird transmission line will be
i nsta 11 ed from Willow to the Kni k J\rm cross i ng duri ng Stage I II
development.
Details of the installation of the cables in trenches in the bed of
the Kni k Arm are to be developed duri ng fi na 1 design.The Kn ik Arm
is primarily a migration route for anadromous species that utilize
the Knik a'nd Matanuska River drainages.The anadromous species
include five speci'es of Pacific salmon,Dolly Varden,eu1achon,and
Bering cisco ..Benthic organisms and other resident species are
sparse because of the excessive amounts of fine glacial sediments on
the sea floor.Alteration of this area from the cable installation
is unlikely and effects upon residEmt or anadromous species are
expected to be minor.
The presence of an operating cable!under the Kn i k Arm is not
expected to affect fish populations.Currently,two electrical
cables cross the Knik Arm near Anchorage.In 1966,an operating
cable was installed from Pt.MacKenzie to Pt.Woronzof.In 1980,an
e1 ectrical cab1 e was p1 aced across the Kni k Arm approximately 7
miles (11 km)north of the Pt.MacKenzie cable.These existing
cab 1es do not appear to have affected the fi sh popu1 at ions.The
operation of a third cable is not.expected to have a significant
impact on the aquatic ecosystem .
134
Table 13.Streams crossed by the transmission line corridor from Willow to
Anchorage.
-
",..
-
"""I
Stream
Ship Creek
Fossil Creek
Otter Creek
Knik Arm
Unnamed Creek
Little Susitna
River
Tributary to
Fish Creek
Fish Creek
Tributaries
to Susitna River
Willow Creek
Approximate miles from
University Substation
in Anchorage
7.5
12.5
18
20-22
26
36.5
45
47
52,53,58
61
Species Present
Chinook,coho,chum and pink
saln!on;Dolly Varden;rainbow
trout;(Arctic grayling)
nOnE!
Sockeye salmon,rainbow trout,1
(Arctic grayling,Dolly Varden)
Chinook,sockeye,coho,.chum and
pink salmon,eulachon,Bering
cisco,Dolly Varden
(Burbot,rain~ow trout,whitefish,
Dollly Varden)
Chinook,sockeye,coho,chum and
pink salmon;Dolly Varden;rainbow
trout;Arctic grayling;(burbot,
whitefish)
(Ch~nook and coho salmon;rainbow
trout,~urbot,whitefish,Dolly
Varden)
Chinook,sockeye,coho and pink
saln!on;rainbow trout;(burbot;
rainbow l trout;whitefish;Dolly
Varden)
(Coho salmon,burbot,rainbow
trout,whi tefi sh,Dolly Varden)1
Chinook,coho,chum,pink and
sockeye salmon;Dolly Varden;
rainbow trout;Arctic grayling,
whitefish;(burbot)
-
1 (species)can be reasonably expected,but not verified
Reference:ADF&G 1978,Fisheries Atlas Volumes I and II
135
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(b)Potential Impacts
Potential impacts associated with the transmission lines from Willow
to Anchorage are similar to impacts previ ously di scussed (Secti on
4.1.1(b»).Additional site specific information is provided.
Impacts duri ng construction are expected to be more severe than
impacts connected with maintenance activities.
(i)Operation and Maintenance Activities
Increased fishing pressure will llikely result from construction
of the transmission lines from Willow to Anchorage.The
transmission corridor is 1ikely to experience heavy usage by
ATV's and snow machines due to the close proximity of dense
population areas such as Willow and Wasilla.CurrentlY,access
by road is avail abl e to the Nancy Lake regi on and the corri dor
will also roughly parallel an e):isting tractor trail from the
Little Susitna to the Susitna River.However,an increase in
fishing pressure on both resident and anadromous species may be
expected at sloughs of the Susitna River west of the Nancy
Lakes region.Fish Creek,other Susitna River tributaries and
the Little Susitna River may become more heavily utilized.
Fi shi ng pressure i ncreases causE~d by the project may have a
moderate impact on the fish resources of the region.
4.2 -Transmission Corridor Mitigation
Mit i gat i on.of potential impacts duri ng transmi ss ion 1i ne construction and
maintenance will be achieved primarily by adherence to the BMPM construction
techniques (APA 1985b,1985c,1985d,1985e,1985f).Proper clearing and soil
stabilization procedures will be followed as Clutlined in the BMP manual on
Erosion and Sedimentation Control (APA 1985b).Shrubs and small trees will be
allowed to revegetate the transmission corridor;the access trail will be kept
clear for maintenance needs.Streams will be crossed utilizing BMPM
procedures (APA 1985b)in order to minimize impacts.Instream activities
required for transmission line construction will be scheduled for mid-summer
136
-
-
,-
months to the greatest extent feasible to aVl)id the biologically sensitive
spawning and overwintering migrations.
Potential impacts of the transmission line construction and maintenance were
described in Section 4.1.Impact mechanisms identified and the corresponding
mitigation measures to be applied during and after construction are discussed
in Section 4.2.1 and are similar to those discussed in Section 2.2.1.
Mechanisms bel ieved to have the largest potemtial impacts to the aquatic
environment requiring mitigation are considered first.Impact avoidance,
minimization,rectification and reduction are discussed.Adherence to the
BMPM techniques is the primary mitigation meaSUlre.
Monitoring of the transmission line through the construction and maintenance
phases will assist in avoiding or minimizing impacts to the aquatic resources.
As described in Section 2.2.2,monitoring will be used to identify
rehabilitation or maintenance requirements for mitigation measures.
Inadequate mitigation measures may be identified and remedied by monitoring
efforts and additional measures.Costs associated with all phases of
construction monitoring are outlined in Table 8.
4.2.1 Impact Mechanisms and Mitigation Measures
-
(a)
(i)
(i 1)
Stream Crossings
Impact Mechanism
During construction and maintenance activities,suspended
solids and petroleum contamination may be increased.Siltation
of downstream reaches may occur'.Fi sh are 1i kely to avoid
areas disturbed by equipment operated in or near streams.
Mitigation
Instream activities will be minimized during the periods of
peak fi sh movement (Figure 5)as descri bed inSect i on 2.2.l.
Previously installed temporary bridges or culverts will be
137
(b)
utilized if available.During the remainder of the open water
season the duration of instream activities will be minimized as
suggested by the BMP manual on Erosion and Sedimentation
Control (APA 1985b).The use of helicopters will avoid much of
the potential instream disturbances in remote areas.
Water Quality
-
-
-
-~i
.-
(i)Impact Mechanism
Temporary degradations in water'quality,including increased
suspended solids and petroleum contamination,could alter
species productivity.
(ii)Mitigation
The primary mitigation measures that will be used to minimize
water quality degradation from transmission line construction
are (1)adhering to the BMPM (APA 1985b)gUidelines;(2)
employing erosion control measures such as runoff control,
stream bank stabilization and re!vegetation;and (3)minimizing
the time necessary to complete instream activity so that water
quality degradations are short-term and non-recurring events.
Additional mitigative measures all'e not expected to be needed.
(c)Increased Fishing Pressure
(i)Impact Mechanism
Sport fishing pressure on local streams and lakes will likely
increase.The transmission line corridor will allow fishermen
to reach areas previously unexploited .
138
-
(ii)
(d)
Mitigation
Section 2.2.1 presents the recommended mitigation for increased
fishing pressure impacts.Modifications to current seasons and
catch limits may be necessary to maintain·current stocks,
particularly along the Wil 1011'1 to Anchorage transmission
corridor.
Oil and Hazardous Material Spilll
,....(i)Impact Mechanism
Spi 11 s of oi 1 and other hazardous substances into streams are
toxic to fish and their food organisms.
-
(i i )Mitigation
Mitigation for oil and haz~rdou:s material spills is described
in Section 2.2.1 and includes the preparation of a Spill
Prevention,Containment and Countermeasure Plan (SPCC)as
required by EPA (40 CFR 112.7)prior to construction
commencement.
-
-
-
-
(d)Water Removal
(i)Impact Mechanism
Fish fry and juveniles can be impinged on intake screens or
entrai ned into hoses and pumps when water is wi thdrawn from
water bodies for miscellaneous uses during construction.
(ii)Mitigation
The construction and maintenance activities will require small
amounts of water wh i ch will be wi thdrawn as descri bed in
Section 2.2.1 to avoid significant impacts.Barren lakes will
139
.....
-
,...
-
....
-
r
-!
be used preferentially as a water source during transmission
line construction .
4.2.2 Monitoring
Monitoring will verify that proper construction practices,as detailed in
the BMP manuals (APA 1985b,1985c,1985d,1985e,1985f),are being
followed during transmission line construction and maintenance.During
transmission line construction,monitorin(~will be conducted to verify
compliance with regulations and permits obtained from the ADEC,ADF&G,
ADNR and Corps of Engineers (COE).The Environmental Field Officer (EFO)
will provide guidance on permit compliance relative to daily activities
as described in Section 2.2.2 .
.After the construction phase,the transmission lines will be periodically
mon i tored as part of the maintenance schedul e.Chron ic eros i on sites
will be identified and corrected;stream crossings will be inspected to
prevent fish passage blockages.Costs associated with the monitoring
program are estimated in Table 8.
140
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