HomeMy WebLinkAboutAllison Creek Hydropower Feasibility Study Volume 1 Report - May 2010 - REF Grant 2195390Copper Volley
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May 2010 IN
H111H ACNE Hatch Acres Corporation May 17, 2010
6 Nickerson Street, Suite 101, Seattle, WA 98109 USA H-327730
Tel: 206-352-5730 • Fax: 206-352.5734 • www..hatchacres.com
Robert A. Wilkinson, CEO
Copper Valley Electric Association
P.O. Box 45
Glennallen, AK 99588-2832
Dear Robert Subject: Allison Lake Hydroelectric Project
Final Feasibility Study
We are pleased to submit herewith our Final Feasibility Study for the Allison Lake Hydroelectric
Project. The development of this study has been performed as Task Orders 01 through 05 under our
Professional Services Contract for General Services between the Copper Valley Electric Association,
Inc. (CVEA) and Hatch Acres Corporation.
The report presents our detailed analysis of the hydroelectric potential of the Allison Lake basin.
Following the review of previous studies, completion of the Pre -Feasibility Report, the Interim
Feasibility Review and a series of engineering and environmental field studies, three options for
hydropower development of Allison Lake are presented in the present study as follows:
• Alternative 1b consisting of a weir at El 1365 and diversion tunnel from Allison Lake to
the Solomon Gulch Reservoir in order to allow increased generation at the existing
Solomon Gulch powerhouse. This alternative differs from the earlier studies in that it
does not include the storage component as provided by the lake -tap proposed for
Alternative 1a.
• Alternative 3c consisting of an independent development of Allison Lake including an
dam that would raise Allison Lake to El 1410, an intake, power conduit and a new
powerhouse near tidewater on Allison Creek.
• Alternative 3d consisting of an independent development of Allison Lake including an
dam that would raise Allison Lake to El 1385, an intake, power conduit and a new
powerhouse near tidewater on Allison Creek.
These three options are evaluated on the basis of their ability to contribute to the CVEA load, the
potential cost of power and the environmental / regulatory issues associated with their development.
All three options demonstrate technical and environmental feasibility. The report includes the
recommendation that CVEA submit a FERC License Application for the project prior to the expiration
of their existing FERC permit for the site. Further, it is recommended that outside sources of state and
federal fundiniz be sought for the aroiect as a means to maximi7P the valiiP of the nroiPrt within the
.. -. -- ---- ----- -- --- r._I__. ..._..... _..__
CVEA electric system.
We greatly appreciate the opportunity to work with you on this interesting project. If you have any
questions regarding the subject report, be sure to give us a call.
Yours very truly,
A. Richard Griffith, P.E.
Project Manager
The Energy Company
Table of Contents
1. Introduction ............................................................................................................................................1
1.1
General..........................................................................................................................................1
1.2
General Arrangements Under Consideration..................................................................................2
1.3
Alternative 1 — Allison Lake Diversion to Solomon Gulch Project, FERC P-2742 (Alt 1).................4
1.3.1 Alternative 1 a.......................................................................................................................
4
1.3.2 Alternative 1 b.......................................................................................................................
5
1.4
Alternative 2 — Allison Lake Tap with Powerhouse on Allison Creek (Alt 2)...................................
5
1.5
Alternative 3 — Allison Lake Siphon Intake with Powerhouse on Allison Creek (Alt 3)....................
5
1.5.1 Alternative 3a.......................................................................................................................
6
1.5.2 Alternative 3b.......................................................................................................................
7
1.5.3 Alternative 3c.......................................................................................................................
7
1.5.4 Alternative 3d.......................................................................................................................
8
1.6
Previous Investigations...................................................................................................................8
1.6.1 HDR Engineering, Inc. and Army Corps of Engineers............................................................8
1.6.2 Hatch Acres Corporation — Pre -Feasibility Study(2007)........................................................
9
1.6.2.1 Conclusions................................................................................................................9
1.6.2.2 Recommendations....................................................................................................10
1.6.3 Hatch Acres Corporation — Interim Feasibility Review(2009).............................................
10
2. Engineering Field Investigations............................................................................................................12
2.1
Topographic Surveys....................................................................................................................
12
2.2
Stream Gage Monitoring Program................................................................................................
12
2.3
Access Road Alignment................................................................................................................
13
2.4
Avalanche Hazard Study..............................................................................................................15
2.5
Penstock / Tunnelling — Feasibility and Costs..............................................................................
15
2.5.1 Drill And Blast Tunneling...................................................................................................
16
2.5.2 Tunnel Boring Machine (TBM)...........................................................................................
16
2.5.3 Microtunnel Boring Machine(MTBM)................................................................................
16
2.5.4 Conclusions.......................................................................................................................
17
2.6
Geotechnical Program..................................................................................................................
17
2.6.1 Regional Geology...............................................................................................................
17
2.6.2 Seismicity...........................................................................................................................18
2.6.3 Geological Mapping...........................................................................................................
18
2.6.3.1 Description...............................................................................................................18
2.6.3.2 Findings....................................................................................................................18
2.6.4 Geophysical Surveys..........................................................................................................
19
2.6.4.1 Description...............................................................................................................19
2.6.4.2 Findings....................................................................................................................19
2.6.5 Borehole Drilling Program..................................................................................................
19
2.6.5.1 Description...............................................................................................................19
2.6.5.2 Findings....................................................................................................................20
2.6.6 Recommendations — Geotechnical Program.......................................................................23
2.6.6.1 Reservoir..................................................................................................................23
2.6.6.2 Dam.........................................................................................................................
23
2.6.6.3 Intake.......................................................................................................................
24
2.6.6.4 Penstock...................................................................................................................25
2.6.6.5 Powerhouse..............................................................................................................25
3. Power Studies........................................................................................................................................ 26
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3.1 AUTO Vista Model: System Loads and Resources........................................................................ 26
3.2 AUTO Vista Model: Allison Lake Hydropower Development....................................................... 26
3.3 Hydrology....................................................................................................................................28
3.4 Reservoir Characteristics.............................................................................................................. 29
3.5 Hydro Equipment Characteristics................................................................................................. 30
3.6 AUTO Vista Results...................................................................................................................... 31
4. Project Construction Cost and Construction Schedule.......................................................................... 34
4.1
Construction Cost Estimates.........................................................................................................
34
4.2
Construction Schedule.................................................................................................................
35
4.3
Economic Analysis.......................................................................................................................
36
5. Regulatory Considerations and Environmental Field Investigations......................................................
38
5.1
Regulatory Considerations............................................................................................................
38
5.2
Environmental Field Investigations...............................................................................................
40
5.2.1 Water Quality Study...........................................................................................................40
5.2.2 Description........................................................................................................................40
5.2.3 Findings.............................................................................................................................
41
5.3
Biological Resources....................................................................................................................42
5.3.1 Literature Review and Gap Analysis...................................................................................
42
5.3.2 Description of Study...........................................................................................................
42
5.3.3 Findings.............................................................................................................................
42
5.4
Recreation and Land Use.............................................................................................................
43
5.5
Archaeological / Historical Study.................................................................................................
43
5.5.1 Description of Study...........................................................................................................
43
5.5.2 Findings.............................................................................................................................
44
6. Conclusions and Recommendations......................................................................................................45
6.1
Conclusions.................................................................................................................................45
6.1.1 Engineering Studies............................................................................................................
45
6.1.2 Regulatory and Environmental Studies................................................................................45
6.2
Recommendations.......................................................................................................................
46
7. References.............................................................................................................................................47
TahlPc
Table 2.1 Roadway Design Criteria
Table 3.1 AUTO Vista Model Elements
Table 3.2 AUTO Vista Hydrologic Years
Table 3.3 Annual Generation - Existing Condition
Table 3.4 Annual Generation - Alt I
Table 3.5 Annual Generation - Alt 3c
Table 3.6 Annual Generation - Alt 3d
Table 3.7 Annual Generation Benefits
Table 4.1.1 Alternative 1b - Total Construction Cost (Bid 1/2010)
Table 4.1.2 Alternatives 3c and 3d - Total Construction Cost (Bid 1/2010)
Table 4.3 Basic Assumptions for Economic Analyses
Table 4.4 First Year Cost of Power (2010 dollars)
Table 5.1 Summary of Major Environmental Studies Conducted
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Figures
Figure 1.1 Allison Lake Hydroelectric Project Location
Figure 1.2 Alt 1 General Arrangement
Figure 1.3 Alt 2 General Arrangement
Figure 1.4 Alt 3 General Arrangement
Figure 1.5 Alt 1a and Alt 2 - Lake Tap
Figure 1.6 Alt 1a and Alt 2 - Tunnel and Pipeline
Figure 1.7 Alt 3 - Pipeline Options
Figure 1.8 Alt 3a - Siphon Intake Facilities
Figure 1.9 Alt 3b - Micro Tunnel
Figure 1.10 Alt 3c - High Dam with Buried Penstock
Figure 1.11 Alt 3d - Lower Dam with Buried Penstock
Figure 3.1 AUTO Vista Model Elements: Existing Hydro System
Figure 3.2 AUTO Vista Model Elements: Alt 1b
Figure 3.3 AUTO Vista Model Elements: Alt 3c and Alt 3d
Figure 3.4 Allison Lake Annual Inflow, 1951 - 1989
Figure 3.5 Allison Lake Reservoir Storage
Figure 3.6 Allison Powerhouse Unit Characteristics - 4 MW Installed Capacity
Figure 3.7 Allison Powerhouse Unit Characteristics - 6 MW Installed Capacity
Figure 4.1 Alternative 3c - Construction Schedule
Appendices
Appendix A - Interim Feasibility Review, CVEA Board Presentation, May 21, 2009
Appendix B - Selected Arrangement, Alternative 3c
Figure BA Project Location
Figure B.2 General Arrangement, Sheet 1 of 2
Figure B.3 General Arrangement, Sheet 2 of 2
Figure B.4 Dam and Spillway, Plan and Sections
Figure B.5 Dam and Spillway, Details
Figure B.6 Penstock, Plan, Profile and Details
Figure 0.7 Powerhouse, Plan, Sections and Details
Appendix C - Engineering Field Investigations
CA Topographic Surveys
C.2 Stream Gage Monitoring Program
C.3 Access Road Alignment
C.4 Avalanche Hazard Study
C.5 Tunnel Feasibility & Cost
C.6 Geologic Mapping
C.7 Geophysical Survey
C.8 Borehole Drilling Program
Appendix D - Power Studies, Alternatives 1b, 3c & 3d
DA Reservoir Elevations
D.2 System Dispatch
Appendix E - Cost Estimate, Alternative 3c, Civil Features
Appendix F - Environmental Field Investigations
FA Water Quantity and Water Quality
F.2 Biological Resources
F.3 Cultural Resources
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
Final Feasibility Report
1. Introduction
1.1 General
The purpose of this Final Feasibility Study is to evaluate the economic viability of alternative
arrangements for the addition of the Allison Lake drainage to the generating resources within the
existing Copper Valley Electric Association (CVEA) electric system. The Allison Lake Hydroelectric
Project (Project) is located adjacent to Prince William Sound immediately south of Valdez, Alaska as
shown in Figure 1.1.
Figure 1.1
Allison Lake Hydroelectric Project Location
p O R T__-- ----
—V- 4 L D E Z
Currently, CVEA's primary source of power is from the Solomon Gulch Hydroelectric Project, a 12-
megawatt hydroelectric facility owned and operated by CVEA. Due to the seasonal pattern of the
power production from this resource, CVEA must also rely on other resources during the winter
months. Most important of these is a 5.2-megawatt cogeneration facility where exhaust heat is
recovered and sold to and used by Petro Star for refining purposes. Diesel -fueled reciprocating
gensets are also operated and maintained by CVEA for supplemental power requirements and for
reserve purposes.
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Although the Solomon Gulch Project operates year round, during winter months the Solomon Gulch
Project operates at reduced levels and CVEA must rely heavily on the above listed fossil resources to
meet system load. The objective for pursuing potential development of Allison Lake is to fill this gap
with additional hydropower generation.
The scope of work leading to this Final Feasibility Study has included the following activities:
1. Data collection
2. Development of general arrangement details of alternative project arrangements consistent
with the purposes of this study
3. Detailed engineering and environmental field investigations of the Allison Lake area
4. Analysis of Allison Lake hydrology and hydropower potential in relation to the existing
Valdez electric system
5. Preliminary layout and cost estimate of hydroelectric project features for each of the
identified project arrangements
6. Economic evaluation of the identified alternatives
7. Environmental review of the of the identified alternatives
8. Preparation of this Final Feasibility Report including the resulting conclusions and
recommendations
1.2 General Arrangements Under Consideration
The three general arrangements reviewed as part of the present study include:
• Alternative 1 (Alt 1) would include an intake and diversion tunnel to the Solomon Gulch
Reservoir in order to allow generation at the existing Solomon Gulch powerhouse during dry
period conditions. Alt 1 includes two optional configurations as described in the paragraphs
that follow.
• Alternative 2 (Alt 2) would include an independent development of Allison Lake consisting
of an intake, tunnel, power conduit and a new powerhouse near tidewater on Allison Creek.
Alternative 3 (Alt 3) would also include an independent development of Allison Lake
consisting of a low dam at the outlet of Allison Lake, an intake, a power conduit that
includes a buried as well surface sections, and a new powerhouse near tidewater on Allison
Creek. Alt 3 includes three optional configurations as described in the paragraphs that
The general arrangements for Alt 1, Alt 2 and Alt 3 are shown in Figures 1.2, 1.3 and 1.4
respectively.
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Figure 1.2
Alternative 1 General Arrangement
Figure 1.3
Alternative 2 General Arrangement
Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
Final Feasibility Report
Suga
Mou
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Figure 1.4
Alternative 3 General Arrangement
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ASUW
F°nf
Im Solomon Lake
o 4
1 O r
a r
= ti.
Allison Lake 1
` ALTERNATIVE 3:
H_ « Surface penstock to
�, Powerhouse @ Allison Creek
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The details of and the options within each alternative are discussed further in the following sub-
sections.
1.3 Alternative 1 — Allison Lake Diversion to Solomon Gulch Project,
FERC P-2742 (Alt 1)
1.3.1 Alternative 1a
Under this scheme, the water from the Allison Lake would be diverted during the low -flow winter
months to replenish the storage in Solomon Lake for hydro generation through the Solomon Gulch
power plant at times when the hydro plant is under utilized or shut down due to lack of water.
Then, when the Solomon Gulch Plant is normally at full output during the spring runoff, Allison Lake
would be refilled.
Alt 1a would utilize a lake tap at El 1250 and a 36-inch conduit to divert water from Allison Lake to
Solomon Gulch as shown in Figure 1.5. This plan would require a lake tap and rock traps, energy
dissipating control valve and a concrete plug to protect the control valve. From the lake tap, the
tunnel as shown in Figure 1.6 would extend at a 3% grade for approximately 10,000 feet to
Solomon Gulch.
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Figure 1.5
Alt 1a and Alt 2 — Lake Tap
Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
Final Feasibility Report
Air Vent
fRodcslide Deflector
El 1367.0 — Max Pool
Active Storage =
El 1267.0 — Min Pool
1367 — 1267 = 100' 8 1250.0 —Lake Tap
Valves
Concrete Plug Nr
Rods Traps
Figure 1.6
Alt 1a and Alt 2 — Tunnel and Pipeline
1.3.2 Alternative 1b
The concept for Alt I is a pure diversion of flow with
minimal civil infrastructure at Allison Lake. The storage
function of Allison Lake would be eliminated entirely. The
tunnel discussed in Alternative 1a would be raised to El
1365. The lake tap, energy dissipating control valve and
other control mechanisms would be eliminated to allow for
free flow of water from Allison Lake to Solomon Gulch.
Water volume would be controlled by way of two weirs at El
1365 and EI 1370 with an additional small orifice to pass a
minimum amount of flow down Allison Creek.
1.4 Alternative 2 — Allison Lake Tap with Powerhouse on Allison Creek (Alt 2)
Alt 2 would utilize a tunnel and penstock leading to a powerhouse located on Allison Creek at El
300. For this scheme, Drill & Blast (D&B) tunneling methods were considered. A D&B tunnel can
be as small as a 10 foot by 12 foot horseshoe shape as shown in Figure 1.6, however, for this small
of a tunnel hand tools will be required to drill each round of blast holes.
1.5 Alternative 3 — Allison Lake Intake with Powerhouse on
Allison Creek (Alt 3)
The Alt 3 group includes four sub -options for the surface / buried penstock configuration as shown in
Figure 1.7. This group of alternatives makes use of a intake and a rockfill embankment dam that
would develop lake storage within the upper portion of Allison Lake rather than all of the project
storage being provided below El. 1364 as with the Alt 1 and Alt 2 alternatives.
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Figure 1.7
Alt 3 — Pipeline Options
1.5.1 Alternative 3a
a Alt 3a utilizes a submerged
i' screened siphon intake with a
• 30-foot high rock fill dam and
Reserrolr pump house. With a
maximum pool at El 1379 and
minimum pool at El 1327, Alt
\a
ConstMcdon Road 3a allows for 52 feet of active
storage capacity as shown in
Figure 1.8. To establish the
maximum possible drawdown
of the lake without the use of a tunnel, a deep trench about 24-feet below normal lake El. 1360 ft,
would be excavated to the centerline of the proposed dam axis. This trench would then contain the
siphon outlet pipe, which would then need to continue to the forebay pool to permit effective use of
the siphon, once it has been primed by appropriate equipment. The siphon piping into the lake
would need to be flexible piping, probably HDPE and extend about 330 feet out into the lake to a
depth of about 1310 feet to permit lake drawdown to El. 1320 ft.
Figure 1.8
Alt 3a — Siphon Intake Facilities
Pump House
Rock Fill Dam
El 1367.0 — Existing Max Pool
El 1379.0 — New Max Pool J,, _ Existing Ground
20'
1327.0 — Min
Buried Pipeline
Submerged Siphon Operation = 20 feet
Screened Intake
Active Storage =
1379 — 1327 = 52"
The first 2,000 feet of the siphon would be under negative pressure in the order of -25 feet due to the
siphon running above the hydraulic grade line. From here, the penstock would continue
downstream as a combination surface / buried arrangement until terminating at the powerhouse
located at El 300 on Allison Creek. Trench excavation for the penstock would be in excess of 25 feet
and pose significant construction challenges.
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1.5.2 Alternative 3b
Alt 3b would utilize a micro tunnel and a 30-foot rock fill dam as shown in Figure 1.9. The surface /
buried penstock and powerhouse would be located similarly to Alt 3a. The micro tunnel allows for
construction of the tunnel at a greater depth than Alternative 3a and thus allows for positive pressure
along the entire length of the penstock. With a maximum pool at El 1379 and a minimum pool at El
1327, Alternative 3b would provide 52 feet of active storage.
Figure 1.9
Alt 3b — Micro Tunnel
El 1379.0
New Max Pool
El 1327.0
Min Pool
2,'
a-M. V ■ Y..I.1.
500 0
Tunnel Pressure > 5 feet
1,400
— 1,380
1,360
1,340
1,320
1,300
500
1.5.3 Alternative 3c
Alt 3c would utilize a 36-inch diameter surface / buried penstock with a 70-foot high rock fill dam at
crest El 1420 as shown in Figure 1.10. The powerhouse would be located at El 300 with a capacity
of 4 MW. With a maximum pool at El 1410 and minimum pool at El 1364, Alt 3c would allow for
46 feet of active storage. This alternative allows for reasonable trench excavation at depths of less
than 20 feet. Due to the relatively low positive pressure in the penstock in the order of 5 feet of
head, penstock pipe material could be made of either steel or HDPE.
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Figure 1.10
Alt 3c — High Dam with Buried Penstock
NE
- 1 �
Hydraulic
Grade
I
..
El 1364.0
Min Pool
36"0 Penstock
_-
1420
1,400
1,380
1,360
i1,340
500 0 500 1,000 1,500 2,000 2,500
Penstock Pressure — + 5 feet
1.5.4 Alternative 3d
Alt 3d differs from Alt 3c in that the dam height is lowered to 45 feet as shown in Figure 1.11 and
the size of the powerhouse is increased from 4 MW to 6 MW. Alternative 3d utilizes a 48-inch
diameter surface / buried penstock. Trench excavation depths and positive pressure along the
penstock are both acceptable.
Figure 1.11
Alt 3d — Lower Dam with Buried Penstock
NE
Hydraulic
—Grade
Line
1
48"(• • Penstock
1,420
1,400
1,380
1,360
1,340
-500 0 \ 500 1,000 1,500 2,000 2,500
Penstock Pressure — + 5 feet
1.6 Previous Investigations
1.6.1 HDR Engineering, Inc. and Army Corps of Engineers
Previous investigations of the Project by HDR Engineering, Inc. (HDR) in 1992 and by the Army
Corps of Engineers (COE) in 1982 evaluated potential project configurations for maximizing the
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Allison Lake resource. In the HDR study, recommendations were made to develop a 12,000-ft-long
tunnel and deep lake tap of Allison Lake for diversion to Solomon Lake. Under this project
configuration, water could be diverted during the winter months for use through the Solomon Gulch
turbine units in a manner comparable to Alt la as discussed above. In the COE study, which was
completed prior to the construction of the Solomon Gulch Project, the COE recommended a stand
alone hydro project similar to Alt 2 as discussed above including a deep lake tap in Allison Lake and
conveyance via tunnel and penstock to a powerhouse (8 MW) on Allison Creek at Tailwater El. 100
ft. More recently, a preliminary permit application was filed for a shallower lake tap on Allison Lake
and siphon system feeding a buried / surface penstock leading to a downsized powerhouse (5 MW)
on Allison Creek at Tailwater El. 150 ft, this arrangement being similar to Alt 3a.
1.6.2 Hatch Acres Corporation — Pre -Feasibility Study (2007)
In the fall of 2007, CVEA authorized Hatch Acres Corporation (Hatch Acres) to perform a pre -
feasibility level review of the hydroelectric potential of the Allison Lake drainage basin.
The primary activities of the pre -feasibility study included the following:
• A reconnaissance review of the project site,
• identification of three potential physical means to develop the hydropower potential of
Allison Lake,
• an evaluation of the power production capability of the selected arrangements,
• cost estimates of each arrangement leading to the cost of power there from and
• an evaluation of the environmental and regulatory issues involved with each arrangement.
The three potential configurations considered in the 2007 review included:
• A lake tap and tunnel diversion of Allison Lake inflow to the existing Solomon Gulch
Reservoir, referred to as Alt la herein.
• A lake tap and tunnel / penstock connecting to a new powerhouse on Allison Creek, referred
to as Alt 2 herein.
• A low dam and siphon intake with an above ground penstock connecting to a new
powerhouse on Allison Creek, referred to as Alt 3a herein.
The results of the study were included in a Pre -Feasibility Study report dated February 2008. The
conclusions and recommendations resulting from study are included below.
1.6.2.1 Conclusions
The conclusions gained from the studies included:
• "The three project configurations studied all have the appearance of being technically
feasible. Arguments can be made on behalf of any of the three as" being the best in this
regard, the truth is yet to be determined through detailed on the ground geotechnical
investigations.
• The three project configurations would all appear to deliver power to the CVEA at a cost less
than the current cost of fossil generation on the basis of reasonably conservative assumptions
for construction cost estimating and financing arrangements.
• All three configurations would benefit greatly from grant monies from the state or more
attractive financing arrangements as provided for under the recently enacted Federal Energy
Act.
• Uncertainties exist in the area of environmental and regulatory process for each of the three
arrangements as follows:
- Alt 1 involves an amendment to the existing license for the Solomon Gulch Project.
The Amendment would be a Capacity Amendment and would potentially open the
terms of the existing license. Issues of concern include:
o Concerns raised by the Valdez Fisheries Development Association (VDFA)
regarding interest in increasing the current minimum flow release from 2 cfs
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to 12 cfs and potential impacts on the hatchery from trans -basin delivery of
water from Allison Lake affecting hatchery operations;
o potential for the resource agencies to request an increase in the minimum
flow release and/or to require better management of the release given the
history of interruptions in delivery of the current 2 cfs release requirement;
and,
o potential for interested participants to request increased recreational access
and related improvements to the trail system. The VFDA raised issues
related to the minimum flow release in the previous license transfer
proceedings. If Alt 1 is selected, CVEA should consider how to address
these concerns given the proposed divestiture of the FDPPA and transfer of
the Solomon Gulch license to CVEA.
- Alt 2 and Alt 3 would introduce a drawdown in the current lake level at Allison
Lake and reduce the current flow from Allison Lake to Allison Creek and tidewater.
- Alt 2, the lake tap, would have the most significant drawdown of the Lake and the
release to Allison Creek may require pumping from the lake to a release to the
Creek.
- Alt 3, the siphon intake arrangement would have the most visual and terrestrial
impact to the area owing to the surface conduit arrangement."
1.6.2.2 Recommendations
Based on the conclusions outlined above, the Pre -Feasibility Study included the following
recommendations:
• "Of three alternatives considered in this study, Alternative 2, the proposed lake tap and
tunnel/penstock with a new powerhouse on Allison Creek, appears to provide the greater
long-term benefit to the CVEA system. However, to preserve any of the three options for
further investigation, we recommend that CVEA prepare an application for preliminary
permit for Allison Lake including the three alternatives stated in this report. CVEA's
Application for Preliminary Permit should be filed at the earliest date possible following
expiration of the permit in effect to Green Power.
• During the first six-month period of the three-year preliminary permit term, narrow the range
of alternatives to focus on the "best fit" to meet CVEA's future demand for electric power.
• Consult with the VFDA, ADF&G, NMFS, USFWS, and the Alaska Department of Natural
Resources (ADNR) water resources, land management and State Historic Preservation Officer
in preparing its Application for Preliminary Permit. The Application for Preliminary Permit
requires a detailed Work Plan be prepared and filed with the Application. These resource
agencies and the hatchery will shape the studies program to be conducted under the terms of
the Preliminary Permit.
• Request approval to use the Alternative Licensing Process (ALP) instead of the required
default integrated Licensing Process (1LP). The ALP allows greater flexibility in scheduling
activities and conducting studies. The iLP is better suited to a relicensing where issues are
related to continuing proiect operations".
1.6.3 Hatch Acres Corporation - Interim Feasibility Review (2009)
Based on the results and recommendations within the 2007 Pre -Feasibility Study, a study plan for the
summer season of 2008 was developed and implemented including the following:
• Topographic Mapping
• Geologic Mapping
• Seismic Refraction
• Construction Road Alignment Alternatives
• Stream Gage Installation (2 locations)
• Resource Agency Consultation
• Environmental Studies
- Fish and Habitat
- Water Quality
- Kittlitz's Murrelet
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- Mountain Goats
- Literature Review & Information Gap Analysis
Details of the 2008 engineering and environmental studies are included in Sections 2 and 5 herein
respectively. The findings, conclusions and recommendations resulting from the 2008 study
program were presented to the CVEA during meetings on May 21, 2009. The set of PowerPoint
Slides used to facilitate these presentations are included in Appendix A.
The focus of the Interim Feasibility Review was on Alt 2, Alt 3a, Alt 3b and Alt 3c. Alt 3b and Alt 3c
were added to the study following concerns raised by CVEA over the reliability of the siphon
operation arrangement for Alt 3a, particularly during the heavy snow conditions during the winter.
Alt 1b and Alt 3d had not as yet been identified for study at the time of the of the Interim Feasibility
Review. Conclusions reached for each of the alternatives under consideration at the time of the
Interim Feasibility Review were as follows:
Alt 1a was removed from further consideration on the basis of its high cost in combination
with issues associated with the FERC License Amendment that would be required for the
Solomon Gulch Project.
With respect to Alt 2, the following conclusions were presented:
- Drill & Blast is a feasible method to construct the Allison Lake tunnel at a minimum cost
of $2,000 per foot (2008 dollars).
- A TBM-driven tunnel is a feasible method to construct the Allison Lake tunnel at a
minimum cost of $2,500 per foot (2008 dollars).
- The expected glacial morainal conditions in the lake bottom are unprecedented for lake
tap construction and present an unacceptable risk to both the construction cost and
reliable long-term operation.
Accordingly, Alt 2 was removed from further consideration
• Alt 3a was removed from further consideration due to the following:
- The depth of excavation required for the penstock downstream of the outlet of Allison
Lake.
- The 2000 feet of the penstock under negative pressure with the siphon arrangement.
- The accessibility of the siphon and penstock during winter conditions for maintenance
or repair.
• With respect to Alt 3b, the following conclusion was presented:
- A Microtunnel Boring Machine is an unfeasible method to construct an upper Allison
Lake tunnel.
Accordingly, Alt 3b was likewise removed from further consideration.
Alt 3c, then, became the "Preferred Alternative" and was reviewed in more detail for the purposes of
the present Final Feasibility Study pursuant to the results of the 2009 field study program, which
included a focus on:
• Core Drilling
• Liquifaction
• Seepage
• Avalanche Hazard
General arrangement drawings for Alt 3c are included in Appendix C.
During the course of the review of Alt 3c, Alt 1b and Alt 3d were identified as technically feasible
arrangements that could significantly reduce the capital cost of the project. These three alternatives
remain as the focus of this Final Feasibility Report.
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2. Engineering Field Investigations
2.1 Topographic Surveys
Topographic mapping for the project area from the outlet of Allison Lake to tidewater of Port Valdez
was prepared using aerial photography and on the ground mapping control. Mapping control is
based on the field survey performed by R&M in September, 2008.
Horizontal control for the field survey referenced NAD83(2007) Alaska State Plane Zone 3, U.S.
Survey Feet values, based on GPS static ties to National Geodetic Survey (NGS) station POWER (PID
no. UV3926). Geophone locations from the seismic refraction survey were surveyed using GPS RTK
(Real-time Kinematic) controlled by broadcasts from project control. Vertical control for the
topographic mapping references vertical datum NAVD88(GEOID06), based on GPS Static ties to
NGS station POWER (PID no. UV3926). The NAVD88(GEOID06) elevation for NGS station POWER
is 9.19 feet.
Aerial photograph -based mapping was provided by AeroMetric-Anchorage, using photography
acquired on 28 August 2007 at a nominal scale of one inch equals 2,000 feet. The aerial
photography was used to produce a digital elevation model (DEM) tied to R&M's field survey. The
result was a topographic map in AutoCAD format with a contour interval of ten feet. The resulting
topographic mapping is illustrated in Appendix CA.
2.2 Stream Gage Monitoring Program
FERC regulations require at least two field seasons of data collection to support an Application for
License. To fulfill these requirements the Allison Creek hydrology study was designed to meet two
objectives:
Obtain a continuous record of stage and discharge on Allison Creek, and develop a flow -
duration curve to display the relationship between stream flow and the percentage of time it
is exceeded at two locations.
Describe Allison Lake/Creek watershed hydrologic regime, including tributary streams,
source and seasonal variation of inflow, and identification of streams and water bodies that
may be affected by construction and operation of the proposed project.
The study was performed by R&M Consultants, Inc. as a subconsultant to Hatch Acres and is fully
uesCribeu in the report entitled 'Interinn Report: 2008-2009 Water Use Study Allison Lake
Hydroelectric Project", dated April 1, 2010, included herein as Appendix C.2. A summary thereof is
included below.
The first phase of the hydrology study established stream gauges at two locations on Allison Creek.
One gauging station was located at the lower end of Allison Creek near the proposed powerhouse
site, and the other near the outlet of Allison Lake. An existing gauging station was located
approximately 1,000 meters downstream from the lake outflow. A continuous record of stage is
obtained by installing instruments that sense and record the water -surface elevation in the stream.
Discharge measurements are then made periodically, to establish a stage -discharge relation and
develop the discharge rating curve.
At each gaging station a pressure transducer/data logger instrument was installed. The pressure
transducer was mounted inside a protective stilling well, which was anchored in the channel at a
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suitable location (stable bed and banks). Following the station installation, a channel cross-section
was surveyed, and an arbitrary gage elevation was established, using a survey benchmark. The
channel energy gradient was also surveyed both upstream and downstream of the gauging station.
Lastly, a discharge measurement was taken at the gage station, using a wading rod and current meter.
In order to develop rating curves for each station, additional discharge measurements were required
at various flow rates. Two discharge measurements were made at each gauging station during high
water conditions in late summer. High water conditions were monitored by observing real-time
discharge information from the adjacent USGS gauging station at Solomon Gulch, and from local
reports. Though all efforts were made to complete discharge measurements at high flow, some
locations and high flow levels presented difficult or unsafe conditions for wading. Therefore, a
fluorescent dye tracer system was used for measuring discharge at high flow levels. A discrete
amount of tracer was poured or injected into the stream over a short time period. At the downstream
measurement site, the concentration was measured continuously with a calibrated fluorometer, from
the first arrival of tracer until all had passed. The determination of the concentration of the entire dye
cloud allowed for the computation of the stream discharge.
Based on the rating curve, the average daily discharge for December through April at Lower Allison
Creek varies between 18 and 25 cubic feet per second (cfs). However, the historic average daily
discharge for winter months at Solomon Gulch is much less; it varies between 10 and 15 cfs for the
same winter period, even though the Solomon Gulch watershed 09.7 sq miles) is larger than the
Allison Creek watershed (7.4 sq miles). Variations in local geology and groundwater seepage may be
responsible for larger winter base flows in the Allison Creek watershed. Until additional winter
discharge measurements are conducted to validate or modify the rating curve, the estimated
discharge values during the winter months should be considered provisional and subject to change.
Previously recorded stream gage data gathered by Green Power Development (GPD) under a
Preliminary Permit from FERC was also reviewed. Prior to recent and current interest, the U.S. Army
Corps of Engineers studied the hydropower potential of Allison Lake in the late 1970's and early
1980's. This effort culminated in a document entitled "Electrical Power for Valdez and the Copper
River Basin: Interim Feasibility Report and Final Environmental Impact Statement", published in
March 1981 (USACE, 1981). This data was also reviewed.
At this time, the results of the stream gauging activities should be considered inconclusive. It is
recommended that data collection be continued until a minimum of three years worth of readings
have been obtained before any firm conclusions can be drawn.
2.3 Access Road Alignment
The preliminary design of a temporary construction access road for the proposed hydroelectric
project at Allison Lake was developed using aerial photography and mapping. The study was
performed by R&M Consultants, Inc. as a subconsultant to Hatch Acres and is fully described in a
technical memorandum entitled "Allison Lake Concept Design (Temporary Construction Road)",
dated April, 2009, included herein as Appendix C.2. A summary thereof is included below.
The goal was to identify the most feasible road alignment that allows for wheeled vehicles — such as
pickup trucks and semi trucks with flat bed trailers — to travel along the project corridor for the
purposes of moving equipment and materials to construct the proposed hydroelectric project. The
project area is mountainous with very steep rocky grades rising 1,100 vertical feet from the
powerhouse to the top of the first peak, a horizontal distance of approximately 3,000 feet. From this
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point to the outlet of the lake, a distance of approximately 6,000 feet, the grades are flatter but the
ground is uneven due to intermittent drainages and large rocks projecting from the silty soils.
Several alignment alternatives were initially developed based on aerial photography and 100'
contour interval mapping. It was assumed that the temporary seasonal road would be constructed
during the first half of the summer season and used to access the site that same year. Some cleanup
due to sloughing slopes and erosion during spring break up would be expected prior to using the
road during the following season. The final intended use, winter use, or decommissioning of the road
has not been determined at this time.
It is anticipated that the construction in steep rocky areas will require significant rock blasting.
Excess rock material will be generated to maintain reasonable grades and construct switch -back
curves. The design uses this excess material ahead on the project to fill and smooth out uneven
terrain along the remaining alignment, and to minimize excavation. Approximately one-half of the
project is heavily covered with brush and some trees. It is assumed that this vegetative waste and any
usable soils encountered would be placed within the footprint of the project.
The following roadway design criteria are for a low speed, one-way road with restricted access.
Widths, grades and slopes are based on a combination of published highway, forestry, and mining
road design criteria and guidelines as listed in Table 2.1.
Table 2.1
Roadway Design Criteria
Item
Criteria
Source
Design Vehicle
WB 50 semi -trailer (40' flat bed trailer)
AASHTO 2004 (Ex2-14)
Design Speed
Varies < 25 MPH
FSH 7709.56 (Sec. 4.25)
Roadway Width
16 ft. plus curve widening and turnouts
BOM (Table 9)
Grades
8% desirable, 20% maximum for short distances
5% maximum on switchback curves
9% maximum before & after switchback cures
BOM (Pg 11)
FSH 7709.56 (Sec. 4.32)
FSH 7709.56 (Sec. 4.32)
Cure Radius
50 ft minimum
ORDOF 2006 (Pg 3-6)
Embankment
Temporary life
Side Slopes
Fill — 2:1 Cut — 1:1 in soil & .05:1 in rock
ORDOF 2006 (Table 3) & R&M Consultants
The preferred alignment would begin at an intersection with the existing Trans -Alaska Pipeline road
and ::ro:.�ld be approximut%lr 3.v 1111—$ in ieiigU . T 1'IiJ IUUtC WOUld CHMU a 2.5: 1 mountain slope to
the plateau area in one continuous network of switch -back curves located on the rocky seaward face
of the first mountain. Excavation would be located in what appear to be more stable rock slopes.
Excess material could be used as fill in areas of less stable soils to minimize excavations in those
areas. Since this route gains elevation more rapidly, it will cross natural drainages closer to the
headwater so there will be less water, lessening the need for erosion protection.
The typical section for the road would have a 16-foot top width that is intended to function as a one-
way temporary road. Switch -back curves should be widened to 25 feet or more and extend back to
provide turn out space to accommodate approaching traffic. Additional turn outs or widened areas
should be provided at inter -visible locations. A 20-inch thick layer of 3-inch minus material has been
included to place on top of the shot rock for a driving surface. Geotextile fabric can be placed under
the base course and over natural ground to provide separation and facilitate construction activities.
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A rough order of magnitude construction cost estimate based on limited information calculated the
construction cost for the road at $5,000,000. Costs are developed from unit prices and preliminary
estimates for excavation, fill, imported surfacing material, and drainage quantities. A contingency has
been included. Final design and construction engineering and administration are not included.
Further field investigations should be conducted to better define soil conditions and verify
construction costs. Rock and common excavation cost includes placing the material as embankment.
Constructing an access road to Allison Lake would indeed be very challenging due to the sheer
steepness of the mountainous terrain. Of those alignments considered, the above described
alignment has been recommended as the "preferred alignment" for the following reasons:
1. Shortest length
2. Avoids most of what appears to be unstable or questionable soils
3. Minimizes drainage crossings
4. Generates excess (shot rock) material to be used as fill in the uneven terrain.
2.4 Avalanche Hazard Study
An avalanche hazard assessment was conducted to assess the potential for snow avalanches to occur
in the project area. The study was performed by Alaska Mountain Safety Center, Inc., which is fully
described in the report entitled "The Allison Lake Hydro Project Snow Avalanche Hazard Evaluation
And Mapping Study", dated June 16, 2009, included herein as Appendix B.4. A summary thereof is
included below.
The avalanche study area encompasses approximately 3.5 square miles of avalanche terrain
containing 114 major avalanche paths. Study of the area was complicated by a lack of onsite snow,
weather, and avalanche data. Many assumptions had to be based upon nearest neighbor data
sources and empirical evidence supported by modeling.
Despite the fact that the avalanche exposure in the Allison Lake drainage is extensive, the overall
project appears well designed to avoid avalanche risk where possible. Two factors would
dramatically increase the risk: a) extending the construction season from summer into winter or
spring months when avalanches are prevalent, and b), excessive removal of vegetative ground cover
(primarily alders) on steep slopes. This vegetation anchors the snowpack to the ground and is the
least expensive, most abundant, and easiest mitigation available.
The entire proposed hydro project infrastructure is affected by avalanches to some degree, but in
most cases the risk is manageable and infrequent. The proposed access road to the dam traverses
numprnnc small avalanche nathc and rrnccpc thn runniit of cnvnral laroor nnnc no r t{,o A— cito
Though posing no risk in summer, this is not the case in winter. The projected dam site is also
exposed — very infrequently — to potential runout from a large avalanche event. If hit, the dam
would be unaffected, but the valve house could be damaged if the hazard is not mitigated with
structural protection. Realignment, burying the pipe, or structural protection would reduce the risk
of possible damage.
2.5 Penstock / Tunnelling — Feasibility and Costs
The conduit system for Alt 1 & Alt 2 arrangements considered as part of the proposed Allison Lake
Hydroelectric project calls for the use of a diversion tunnel under the ridge separating Allison Lake
and the Solomon Gulch Reservoir. Three tunneling methods for construction were considered by
the Hatch Mott McDonald Group as discussed in their memorandum entitled "Assessment of
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feasibility and cost to construction penstock tunnel", dated March 31, 2009, included herein as
Appendix C.5. A summary thereof is included below.
2.5.1 Drill And Blast Tunneling
The first tunneling method considered was Drill & Blast (D&B). The D&B tunnel can be as small as a
10 foot by 10 foot horseshoe shape, however, for this small of a tunnel hand tools will be required to
drill each round of blast holes. Similarly, all other activities necessary to construct a small D&B
tunnel will require smaller equipment with lower productivity rates. Consequently, D&B
construction costs for the minimum size tunnel can be equal to or greater that the cost of a larger,
more efficiently constructed, D&B tunnel.
A D&B operation can be mobilized quickly and supported by either access road or helicopters.
Helicopter support was the approach utilized for the recently completed Lake Dorothy Hydroelectric
Project in southeast Alaska. However, helicopter -supported construction has a significant cost
premium and a higher risk of weather delays.
Cost estimates for D&B tunnel construction can vary significantly and are dependent on crew size
and experience, equipment costs, and market conditions. Upon review of recent construction costs
for Lake Dorothy and using current labor and equipment rates, it is estimated that a 10-12 ft by 10-12
ft D&B tunnel supported by either access road or helicopter would cost a minimum of $2,000 per
foot to construct at this site. The D&B tunnel is considered a feasible option.
2.5.2 Tunnel Boring Machine (TBM)
The second tunneling method considered requires a TBM-driven tunnel constructed from an access
road midway to Allison Lake. This method is considered feasible but has the following significant
constructability issues. TBM mobilization can require 20 to 30 semi -truck loads of equipment
components and materials and the heaviest components require special multi -axle semi trucks that
warrant consideration of roadway geometry and load restrictions. Staging, assembly, and launching a
TBM requires a substantial yard area at the tunnel portal. TBM drives are typically supported by a
railroad constructed in the tunnel to move spoil out and supplies in. A spoil dump and load out
station are required to transfer the spoil to trucks for hauling to the disposal site. All of the above
issues, as well as the need for maintenance shops and material stockpiles, make a TBM portal located
in the middle of a steep slope midway through a series of access road switchbacks problematic.
2.5.3 Microtunnel Boring Machine (MTBM)
A third tunneling method would require a MTBM to constrict an unnar a nnn-font Inns t11nnA1 in
two drives from a centrally located launch shaft. The first drive would be towards Allison Lake with
a wet retrieval of the MTBM. The second drive would be towards a drop shaft site that connects to a
lower rock tunnel. The subsurface conditions along the microtunnel alignment have not been
explored with borings or trenches. Geophysical refraction surveys completed as part of the
reconnaissance investigation indicate thick soils that range from 40 to more than 100 feet in
thickness that overlay bedrock. Field reconnaissance by Hatch Energy identified numerous very large
blocks of rock (greater than 1,000 cubic feet in volume) randomly scattered along the upper tunnel
alignment.
Specially equipped MTBMs are capable of advancing through boulders at a reduced rate with
increased wear on the cutting tools. Though it is technically feasible to drive a MTBM through large
boulders, an unknown number of very large blocks of rock at random locations along the
microtunnel alignment represents a significant risk to the successful completion of the drives. A worst
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case scenario for the MTBM drives would include unexpectedly encountering one or more very large
blocks of rock that would necessitate either construction of temporary access roads and rescue shafts
to recover and re -launch the MTBM or abandonment of the MTBM and completing the tunnel by
conventional methods. In either case, cost and construction schedule could easily double. Therefore,
the risk of encountering multiple very large blocks of rock represents a fatal flaw to the concept of
microtunneling an upper tunnel for the Allison Lake Hydropower Project.
2.5.4 Conclusions
The conclusions resulting for the above described review include the following:
• Drill & Blast is a feasible method to construct the Allison Lake tunnel.
• A Drill &Blast tunnel constructed at this site would cost a minimum of $2,000 per foot.
• A TBM-driven tunnel is a feasible method to construct the Allison Lake tunnel.
• A TBM-driven tunnel constructed at this site would cost a minimum of $2,500 per foot.
• A Microtunnel Boring Machine is an unfeasible method to construct an upper Allison Lake
tunnel.
• A soil lake -bed is considered to constitute a fatal flaw to the use of a lake tap as a tunnel
intake.
2.6 Geotechnical Program
Allison Lake is located at an elevation of approximately 1,365 ft on the south side of the fjord of Port
Valdez, and approximately 2 miles inland. Over the first 2,000 ft downstream of the lake outlet,
Allison Creek drops in elevation to about El. 1,300 ft. Between approximately 2,000 ft and 3,000 ft
downstream from the lake, Allison Creek drops from El. 1,300 ft to El. 1,200 ft, after which the creek
descends the steep side of Port Valdez fjord to tidewater.
A program of geotechnical work was carried out in 2008 and 2009 by R&M Consultants, Inc. The
geotechnical investigation program included:
• Geological mapping of the area of the Project
• Seismic refraction survey profiles taken across the lake outlet and along the valley bottom
downstream from the lake.
• Drilling of six exploratory boreholes, consisting of one on either side of the creek at the lake
outlet, one on either side of the creek on the upstream side of the proposed dam, and two
on the valley floor approximately 1,200 ft and 2,200 ft downstream of the dam axis. The
depth of the test borings ranged from 52.2 ft to 122 ft.
2.6.1 Regional Geology
Reference is made to the description of regional geology to be found in the report for the Four Dam
Pool Power Agency, entitled "Solomon Gulch Hydroelectric Project, Supporting Technical
Information (STI) Document" dated January 2008. That report drew upon information from the 2002
P12D Report, Section 4, and from an initial geology report for Solomon Gulch entitled "Geology and
Foundation Investigations.
The geology of the area is characterized by its glacial and tectonic history. The regional bedrock is
reported to be part of the Valdez Group, consisting of late Cretaceous marine sedimentary and
metasedimentary rocks, which in the area of the site consist predominantly of graywacke, with lesser
amounts of argillite and slate. On a regional scale, the bedrock is reported to occur in thin beds that
dip steeply to the north and are strongly jointed, folded and extensively faulted. In the Allison -
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Sawmill Creeks area, intercalated and interlayered metagraywacke and phyllitic argillite are reported
to dominate the bedrock lithology.
2.6.2 Seismicity
Allison Lake is situated in a region of very active seismicity, primarily associated with the Pacific
Plate moving north -northwesterly at about 45 to 50 mm/year, and subducting under the North
American Plate. Known earthquake sources capable of producing strong ground motions at the
project site include the Aleutian megathrust, the Wadati-Benioff zone, the Yakataga subduction and
transition fault, the Kayak Island, Heney and Ragged Mountain faults, and possibly other less well
known faults. The project area is less than 60 miles from the epicenter of the 1964 Great Alaska
Earthquake, which was M9.2.
An evaluation of seismicity for the nearby Solomon Gulch Dam, reported in January 2008,
recommended peak accelerations for rock foundations of 0.5g and 0.24g for the Safety Evaluation
Earthquake and the Operating Basis Earthquake respectively. The bedrock accelerations at Allison
Lake will not be significantly different. However, whereas Solomon Gulch Dam is founded on firm
bedrock, the dam, spillway and penstock of the Allison Lake Project would be founded on a deep
soil deposit. The effect of the soil foundation is that the bedrock accelerations will be amplified,
producing greater accelerations at the ground surface.
2.6.3 Geological Mapping
2.6.3.1 Description
As part of a geotechnical reconnaissance investigation, geological mapping of the project area was
undertaken by R&M Consultants Inc. in September 2008, using color aerial photographs, helicopter
reconnaissance and field traverses. The investigation is fully described in the report entitled
"Geotechnical Reconnaissance Investigation — Allison Lake Hydroelectric Project", dated April 1,
2009, included herein as Appendix C.6.
The surficial geology was mapped in terms of terrain units, and the interpretations were verified by
drilling investigations, helicopter reconnaissance, and field traverses. In addition to mapping the
surface geology, bedrock structures were mapped and measured to determine the rock mass quality
and discontinuity characteristics. The mapping was recorded on a mosaic of aerial photographs.
2.6.3.2 Findings
The findings of the aerial photograph interpretation are to be found on figures in Appendix A of the
above referenced report.
Glaciation has shaped the topography in the project area. The Allison Creek valley between Allison
Lake and the steep wall of the Port Valdez fjord is covered by moraine and outwash deposits. The
ground surface is hummocky and is littered with glacial erratic boulders. The areal density of large
angular boulders is quite remarkable in the first 1,000 ft downstream from the lake outlet.
At the south (inlet) end of Allison Lake, the valley floor consists of glaciofluvial deposits. The east
and west shores of the lake are mapped mainly as inactive talus slopes, with occasional alluvial fans
where there are natural drainage gullies.
Allison Lake has been formed by a terminal moraine deposit that created a natural dam on Allison
Creek. From the lake outlet, Allison creek occupies a broad flat U-shaped valley that extends for
approximately 3,000 ft, after which the valley shape transitions to V-shaped and Allison Creek begins
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its rapid descent to the ocean. The depth of the moraine in the vicinity of the lake outlet is not
precisely known. The moraine is described as unsorted, non -stratified, coarse to fine, angular rubble,
with large angular erratics up to 20 ft or more in size dispersed throughout the deposit.
The steep portion of the Allison Creek valley has been mapped as covered by colluvium. Where the
creek approaches the ocean, the ground is covered by alluvial fan deposits and fill.
2.6.4 Geophysical Surveys
2.6.4.1 Description
In September 2008, R&M Consultants Inc. carried out a series of seismic refraction profile surveys as
described in the report entitled "Seismic Refraction Survey — Allison Lake Hydroelectric Project",
dated April 1, 2009, included herein as Appendix C.7.
Lines 1, 2 and 3 join to give a profile across the valley at the outlet to Allison Lake. Lines 4 and 5
combine to give a profile approximately 5,000 ft in length along the valley from the lake outlet to the
top of the steep slope of the fjord.
2.6.4.2 Findings
The results have been plotted in terms of contours of seismic velocity. They are interpreted to
indicate an upper zone of poorly consolidated soil deposits, with more dense soil below. The lowest
layer has seismic velocities that may indicate the presence of dense till. There were no distinct
signals that would confidently indicate the presence of bedrock within 200 ft of the ground surface.
The interpretation of the geophysical profile is doubtless hampered by the number of very large
boulders that are present within the moraine.
The results are presented as three contours of P-wave velocity, namely 2,500, 4,500 and 6,500 ft/s.
For comparison, seismic refraction profiling performed at Solomon Gulch, where the bedrock is
exposed and is believed to be quite similar in quality to the buried bedrock at Allison Lake, gave
much higher seismic velocities. At Solomon Gulch the reported seismic velocities were 14,500 to
17,500 ft/s in very hard rock, 11,500 to 13,200 ft/s for fine grained slate interbedded with argillite,
and 8,500 to 9,700 ft/s for the weakest slates and argillites. Thus it is concluded that the materials
with the greatest seismic velocities at Allison Lake are dense soil and dense soil with boulders.
2.6.5 Borehole Drilling Program
The program of geotechnical work carried out in 2009 by R&M Consultants, Inc. is described in the
rennr+entitled "ori=ii�i�inaiy GUVL1=%.111111.a1 li1'vc5A%CILioil, AIIlSUI1 LdKe Hydroelectric Project", dated
fort
March 26, 2010, included herein as Appendix C.B. A summary thereof is included below.
2.6.5.1 Description
Three test borings were made by the U.S. Army Corps of Engineers (COE) in September -October
1978, and six were made by R&M Consultants Inc. in July 2009. The locations of these nine holes
are shown on Drawing A-01 in Appendix A of the report entitled "Preliminary Geotechnical
Investigation Allison Lake Hydroelectric Project", dated March 26, 2010, by R&M Consultants Inc.,
which contains details of the 2009 campaign of field investigations and testing.
Of the 1978 USACE Drillholes, DH-1 was located in the area of a proposed lake tap and diversion
tunnel, and DH-3 was located in the area formerly proposed for the powerhouse. Drillhole DH-2
was located roughly midway between Drillholes DH-1 and DH-3. The purpose of Drillhole DH-2
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was to investigate ground conditions for a possible water tunnel between the lake and the
powerhouse site.
Of the holes drilled in 2009, TH-3 and TH-4 were drilled into the moraine on a suggested alignment
for an earth dam, one on each side of the creek; TH-1 and TH-2 were drilled in the moraine
upstream of the suggested dam position and close to the seismic profile positions; and TH-5 and TH-
6 were drilled some distance downstream, close to the seismic profile that was taken along the
valley.
The purpose of the 2009 exploratory holes was:
• Characterize subsurface conditions at several points on the existing seismic refraction survey
lines to add confidence in the interpretation of the seismic data;
• Investigate the foundation soil conditions, including liquefaction potential, at the proposed
dam location;
• Characterize the hydraulic properties of the soils, and establish the existing phreatic surface
downstream, to allow for an analysis of seepage beneath the proposed dam; and
• Characterize properties of potential materials for use as dam embankment material, and
penstock backfill material.
Standard Penetration Tests were performed in all boreholes and soil specimens were obtained using
split spoon samplers. Samples were submitted for gradation, moisture content and index testing.
A standpipe piezometer was installed in each borehole, and falling head percolation tests were
performed in several of the boreholes.
2.6.5.2 Findings
Holes Drilled in 1978
Of the exploratory boreholes drilled in 1978, Borehole DH-1 was drilled on the west side of Allison
Lake, near where a lake tap had been proposed. The borehole penetrated to a depth 175.8 ft, of
which 142.6 ft was drilled in bedrock. The overburden consisted of sand and boulders, and is
probably colluvial in origin. The bedrock consisted of metagraywacke with sandstone and shale
zones. Artesian flows were recorded in the top 10 ft of the hole and below 106 ft depth.
Borehole DH-2 was drilled approximately 4,000 ft downstream from the lake. It was advanced to a
depth of 64 ft without reaching bedrock. The uppermost 20 ft contained from 50% to 70% boulders,
mixed with sand and gravel. The largest boulder encountered by this borehole required 3.5 ft length
of core drilling to go through it. Below 20 ft, there was gravelly sand, silty sand and cobbly sand. A
weathered surface was identified at 48.9 ft depth, which was interpreted to be the interface between
overlying re -worked till and the parent till. Permafrost was suspected at a depth of between 20 ft and
30 ft, although the region is considered to be generally free of permafrost.
Borehole DH-3 was located near tidewater at a location that was considered suitable for the
powerhouse. This borehole revealed 17 ft of alluvial gravel and a 3 ft thick layer of boulders
overlying till that contained 25% to 45% boulders. Metagraywacke bedrock was encountered at
68.8 ft depth.
Holes Drilled in 2009
None of the 2009 boreholes reached bedrock. The drill frequently encountered boulders. Where
the borehole log records a length drilled through a boulder, it is unlikely that the length of drilling
within the boulder corresponds to the true size of the boulder. In borehole TH-3, a boulder was
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
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penetrated for 27.2 ft, which informs us that the boulder was at least that size. The boulders consist
predominantly of graywacke.
Groundwater observation wells (standpipe piezometers) were installed in all of the 2009 boreholes.
However, because of difficulty of access in winter, to the present date no readings have been taken
from these standpipes.
Borehole TH-1 was drilled on the right bank of Allison Creek near the lake outlet, and about 600 ft
upstream of the proposed axis of the dam. It was drilled from El. 1,430 ft to depth of 90 ft. A
boulder was recorded between 1 ft and 4 ft depth, below which is poorly graded gravel with silt and
sand to silty gravel with sand containing cobbles and boulders. In this material, water circulation
was lost at 9 ft, returned at 15 ft, was lost again at 28 ft, and returned at 36 ft. The water level in the
borehole was measured during drilling at a depth of 84 ft (corresponding to El. 1,345 ft). However,
circulation of drilling water was again lost at the end of the hole (90 ft depth), which suggests that the
true water table may be lower. These data suggest that the foundation for the lake basin when raised
by the dam will not be adequately watertight without an impervious blanket.
The Standard Penetration Test results for TH-1 indicate that the foundation would be adequately
strong to support the load of an embankment dam of the planned height.
Borehole TH-2 is on the left bank of Al Iison Creek near the lake outlet, and about 750 ft upstream of
the proposed axis of the dam. It was drilled from El. 1,370 ft to depth of 53.2 ft. Similar to TH-1,
this hole encountered poorly graded gravel with silt and sand to silty gravel with sand containing
cobbles and boulders. Circulation of drilling water was lost at 28 ft depth. The watertable was
measured at El. 1,340 ft, which is similar to the elevation in TH-1, and some 25 ft lower than the
water level of Allison Lake.
The Standard Penetration Test results for TH-2 indicate that the foundation would be adequately
strong to support the load an embankment dam of the planned height.
Borehole TH-3 is on the left bank of Allison Creek about 250 ft upstream of the proposed axis of the
dam. It was drilled from El. 1,382 ft to depth of 97.5 ft. Similar to TH-1 and TH-2, this hole
encountered poorly graded gravel with silt and sand to silty gravel with sand containing cobbles and
boulders. This hole was drilled through a massive boulder of graywacke between 10 ft depth and
37.2 ft depth. Circulation of drilling water was lost at 47 ft, returned at 53 ft, was lost again at 63 ft,
returned at 75 ft, and was lost again at 78 ft. The water level in the borehole was measured at a
depth of 57.5 ft, corresponding to El. 1,327.5 ft. This is some 40 ft lower than the water level of
Allicnn I alta Whirh is come tine # nnctro m of TV 3
The water losses and low water table suggest that control of seepage through the foundations will be
necessary. However, the incidence of cobbles and boulders suggests that it would be difficult to
create a narrow cutoff, and a wide excavated cutoff trench would be required. Access to the site by
the construction road that will ascend the valley wall of the fjord will restrict the size of construction
equipment that could be brought to the site.
The Standard Penetration Test results for TH-3 indicate that the foundation will be adequately strong
to support the loading from an embankment dam of the planned height. The SPT results and the
material gradations suggest that the foundation soils are dense, porous and well graded, and
therefore unlikely to be susceptible to seismic liquefaction.
Borehole TH-4 is on the right bank of Allison Creek close to the position of the upstream toe of the
proposed dam. It was drilled from El. 1,376 ft to depth of 62.2 ft. Similar to TH-3, this hole
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encountered poorly graded gravel with silt and sand to silty gravel with sand containing cobbles and
boulders. Standard Penetration results are consistent with dense gravel. Circulation of drilling water
was lost at 16 ft, returned at 35 ft, and was lost again at 48 ft. No groundwater was observed in the
borehole, which is taken to mean that the water table is below the end of the borehole at El. 1,313.8
ft. Thus the water table at the dam site is more than 50 ft lower than the water level of Allison Lake.
From this, it is interpreted that the foundations at the dam site are pervious and underdrained. It is
judged that subsurface seepage control measures should be considered for a dam at this location.
Borehole TH-5 is on the left side of Allison Creek approximately 1,200 ft downstream of the
proposed dam location. This hole was drilled from El. 1,365 ft to a depth of 122 ft through soils
consisting of sand, gravel, cobbles and boulders similar the soils logged in the other boreholes.
Bedrock was not reached. Groundwater was encountered at El. 1,293 ft.
Borehole TH-6 is also on the left side of Allison Creek and is approximately 2,200 ft downstream of
the proposed dam location. This hole was drilled from El. 1,252 ft to a depth of 52.2 ft through soils
consisting of sand, gravel, cobbles and boulders similar the soils logged in the other boreholes.
Bedrock was not reached. No groundwater was encountered.
Laboratory Test Data
Split spoon samples were taken in each borehole. The sampling method excludes particles larger
than about 2.5 inch size, and because the split spoon cannot be used where larger stones are
present, the sampling method tends to over -represent the more fine-grained strata. A total of 20
particle size gradation tests were made. The samples contained between 4% and 20% fines (silt and
clay), except for a sample from 105 ft depth in TH-5 that contained 40% fines. All of the samples
that were tested were non -plastic. Throughout the range of sand and gravel sizes, all of the samples
were well graded sandy gravel except for a sample from TH-6 at 30 ft depth that was 84% gravel
sized.
Field Permeability Tests
It is difficult to obtain reliably accurate in situ permeability tests in dense gravels such as are present
at this site. Nevertheless, six falling head tests were performed in boreholes TH-1, TH-2, TH-4 and
TH-6. All of the tests reported low hydraulic conductivity, with the highest permeability reported
being 5E-4 ft/s (1.5E-6 cm/s). During the drilling, loss of drilling fluid circulation occurred at least
once in every test boring. This was interpreted to be caused by voids, or pockets of open coarse
grained material. In most cases the circulation resumed, likely when the voids had become filled or
plugged- 7nnec of high narmaabilihi ara not evna`- 4 fn he . t-A
All of the tests were performed in the HQ -size core barrel, with the end of the barrel on the bottom
of the hole. Because the core barrel was equipped with a bit designed to allow drilling fluid to flow
around the outside of the barrel, it was assumed for the purposes of the falling head tests that the
hole could be considered as being effectively an uncased hole. The calculation of the in situ
permeability is directly proportional to the length of hole that is assumed to be effectively uncased.
If the end of the casing were assumed to be sealed onto the bottom of the hole, and the permeability
calculated as an open-ended casing test, the calculated soil permeability values would have been
orders of magnitude greater.
Standard Penetration Tests
Except for a single outlier, there are no tests below a depth of 15 ft that gave an N-value less than 25.
This is indicative of dense well -graded soil below 15 ft depth.
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2.6.6 Recommendations — Geotechnical Program
2.6.6.1 Reservoir
The material covering the bed of Allison Lake has not been tested to determine its impermeability.
However, because the lake is fed by glacial headwaters, it has been conjectured that the bed below
water level will be covered by a relatively impervious seal of glacial silt. If the lake level were to be
raised by the proposed dam, the banks above the natural lake level will not be sealed with glacial silt
and thus may not be as impervious as the natural lake bed. In fact the inflow of groundwater into
DH-1 suggests that the colluvial soils along the shore are quite permeable. The proposed scheme as
conceived requires the level of Allison Lake to be raised from about El. 1,365 ft to El. 1,410 ft in
order to increase the live storage and also to provide the necessary minimum submergence on the
intake and low pressure section of the penstock. With the raised reservoir level, Allison Lake will
extend roughly 700 ft downstream to the proposed dam, so that the colluvial lake shores and a large
unsealed area of granular moraine on the upstream side of the dam would become flooded. Further
site investigations would be needed to confirm the permeability of the moraine, and even then it is
unlikely that the amount of seepage could be predicted with any great accuracy. Apart from the
possibility of systematic leakage under and around the ends of the dam, there are no indications of
any buried valleys or other definable leakage paths that could compromise the reservoir
watertightness.
In a major earthquake, there is the possibility that a landslide could develop in the steeply dipping
beds on the slopes above the lake. This has not been examined in detail. However, a high velocity
rockfalI, if large enough, could generate a displacement wave that would be damaging to an
embankment dam.
2.6.6.2 Dam
The location of the proposed dam is shown on Figure 0.2. A cross-section of the highest part of the
dam is shown on Figure B.4. The proposed dam site has been chosen based on topographic
considerations. It is located on the moraine that blocks the natural drainage to retain the lake. This
landform is most likely a terminal moraine. The ground surface at the dam site is covered by large
angular glacial erratics that appear from the rock types to be of local origin. The exploratory
boreholes encountered similar boulders throughout the depth that they were drilled. The foundation
soils are judged to be adequately strong to support an embankment dam of the intended height with
3h:1 v upstream and downstream slopes. That these are safe slopes must be verified for the design
earthquake loadings.
In order to safeguard against seismic liquefaction, it is recommended to remove the uppermost 15 ft
of soil and boulders under the entire footprint of the dam. This recommendation is based upon the
observation that the SPT N-values below 15 ft depth are consistently better than 25. The largest
boulders will need to be blasted to remove them. With the natural ground elevation at 1,364 ft, 15 ft
of general stripping brings the foundation surface to El. 1,349 ft. A freeboard of 10 ft to allow for
flood surcharge, wave run-up and settlement would bring the crest level of the dam to El. 1,420 ft.
Thus the maximum dam height is 56 ft.
Because of uncertainty over the permeability of the dam foundations, subsurface seepage control has
been included in the design. A cutoff trench has been recommended in preference to a diaphragm
wall because the remoteness of the site will make it costly to mobilize specialized equipment, and
because the difficulty of access along the site construction road will make it costly to bring large
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equipment to the site. Furthermore, a diaphragm wall excavator would almost certainly meet refusal
on the large boulders that occur throughout the moraine foundation.
It may be possible at a later stage to reduce the depth and lateral extent of the cutoff trench if more
exploratory drilling and permeability testing of the foundation soils were done. However, for this
feasibility study it is recommended that a subsurface seepage cutoff should be included. The
intended purpose of the cutoff is to reduce the quantity of seepage (the water available for power
generation being more valuable than is usual for a dam of this type) and to control seepage gradients
that might otherwise predispose to a piping failure of the dam. Under the highest section of the dam,
the recommended cutoff trench is 40 ft deep below the general stripping level, and 40 ft wide at the
base. The depth of the trench will reduce towards the abutments. The width of the trench bottom
has been chosen to provide adequate access space for construction of a central asphaltic core and its
sand filters, and to control seepage flows and seepage gradients under the asphaltic core. Safe
temporary sideslopes for the trench excavation are judged to be 1 h:1 v. The extent to which the
subsurface cutoff will need to continue beyond the ends of the dam has been determined only very
approximately for this study.
The dam embankment is intended to be built of the morainal material after the boulders have been
separated out. The boulders would be used for riprap. A 1-m wide vertical asphaltic core has been
recommended to provide the impervious barrier in the embankment. The asphaltic core will be
protected on its upstream and downstream sides by sand filter zones. The width of the core and the
filter zones will be sufficient to maintain integrity after displacement by the design earthquake.
Asphaltic material has been recommended for the core construction because suitable impervious fill
has not been identified within reasonable distance of the site, and because asphaltic construction
may continue at times when wet or cold weather conditions would be unfavorable for compacting
silt and clay soils.
The location, cross section and profile of the proposed spillway is shown on Figures B.4 and B.5.
The drilling program as described above indicates that the bedrock in the area of the dam is too deep
to provide an obvious location for a conventional spillway. Furthermore, the conditions around the
dam do not provide a consistent foundation for a spillway structure. Accordingly, it is proposed to
build an ungated overflow spillway on the dam embankment where it will be possible to have
control of the foundation conditions. For this arrangement, energy dissipation would be provided by
a stepped spillway and a stilling basin, with substantial rock armoring placed for some distance
downstream from the dam to control erosion.
F F 2 Intake
The intake for the penstock is shown on Figure B.4 It would be a free-standing concrete structure
founded on moraine soils. The inlet would be set low enough to operate at the lowest planned
operating level, taking into account the maximum thickness of ice cover. This is assumed to be close
to the present natural lake level.
The intake structure must be sufficiently massive to resist flotation and able to resist ice thrust. It may
be necessary to excavate a 10 ft or so below the natural ground surface to provide adequate
foundation conditions. If built close to the present lake shore, the excavation for the intake
foundation may require measures to control inflows of water. Conventional sheet piling would
almost certainly meet refusal on the boulders in the moraine. Consequently, it may be better to site
the intake close to the dam where the watertable is known to be well below the lake level. An
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
Final Feasibility Report
approach channel would then be excavated between the intake structure and the lake at its lowest
operating level.
2.6.6.4 Penstock
The penstock route is shown on Figures B.2 & B.3 and the overall plan, profile and details are shown
on Figure 0.6. The penstock will be buried for the first 2,300 ft of its length. In this length, the
depth of excavation is generally less than 20 ft. Excavation will necessitate blasting the largest
boulders. After Station 2,300 ft, the penstock may be founded at the ground surface on bedrock or
colluvial soils. In this length, the slopes above the penstock will warrant careful examination to
evaluate avalanche risk and the potential for landslides to develop.
2.6.6.5 Powerhouse
The locations of the powerhouse and tailrace channel are shown on Figure B.7. The powerhouse
would be founded on gravels of an alluvial fan deposit where Allison Creek debouches into Prince
William Sound.
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3. Power Studies
AUTO Vista was used to evaluate the generation benefits of various upgrade configurations under
consideration for the Project during the Pre -Feasibility Study and the Interim Feasibility Review. As
stated at the close of Section 1, the focus of this Final Feasibility Report includes Alt 1b, Alt 3c and
Alt 3d as discussed below.
AUTO Vista is one of the several components of a decision support system, Vista, which was
developed by Hatch Acres for use by system dispatchers and engineering operations staff, to assist
them in short- and long-term scheduling to achieve maximum value for the generation system. In
this case, the AUTO Vista component was used as an analysis tool to evaluate the economic value of
alternative project configurations and methods of operation. It considers plant characteristics, water,
pricing, and system load constraints in its calculations.
The following is a description of the program and a discussion of the use of AUTO Vista on this
project.
3.1 AUTO Vista Model: System Loads and Resources
The AUTO Vista model operates on an hourly time step to meet system loads in the most cost
effective manner using available system resources as a function of their respective cost of production.
For the present study, the system load was based on CVEA data for 2006. The system resources
considered for the existing case included the combined diesel plant facilities in Valdez and
Glennallen, the combined cycle unit as operated under the contract with Petro Star, and the existing
hydropower facilities at the Solomon Gulch Project. The proposed development included the
additions as discussed in Section 2 above as well as retirement of the existing thermal generation
resources to the extent possible in each respective case under consideration.
3.2 AUTO Vista Model: Allison Lake Hydropower Development
The AUTO Vista model for the Project includes the drainage basins for both the existing Solomon
Gulch Hydroelectric Project and Allison Lake. It is comprised of a series of arcs and nodes with each
element having its set of characteristics. These basic elements and typical data associated with each
are summarized in Table 3.1.
Table 3.1
AUTv visia Model Elements
Element Typical Characteristics
Arcs
Inflow Hourly inflow at discrete points within drainage basin
Spillway Spillway rating curves / discharge requirements
Open Channel (Streams) Minimum flows / ramping rates
Closed Conduits (Penstocks) Head loss coefficients
Nodes
Reservoirs Area -capacity data / elevation & discharge constraints
Powerhouse Units Efficiency data / maximum & minimum flows
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The graphical model for the existing system, Alt 1b, Alt 3c and Alt 3d as expressed in these terms is
shown below in Figures 3.1, 3.2 and 3.3. Major features of the AUTO Vista model are briefly
described below.
Figure 3.1
AUTO Vista Model Elements: Existing Hydro System
SLGQ
(Solomon Gulch Inflow)
y
SLGR
Solomon Gulch Reservoi
SINS SLGS
( omon (Solomon Gulch Spill)
SLGP Instrea Flow)
(Solomon Gulch Power)
SLGT SLGS_RJ
(Solomon Gulch SPWY Junction)
(Solomon GulchTWL)
SLGINS_RJ
(Solomon Gulch INS Junc)
S_SINK
(Sou roe_Sin k)
Figure 3.2
AUTO Vista Model Elements: Alt 1 b
SLGQ
(Solomon Gulch Inflow)
ATPS
y
(Allison Lake Tap)
SLGR
(Solomon Gulch
Reservoi
SINS SLGS
(
olomon (Solomon Gulch Spill)
SLGP Instre
Flow)
(Solomon Gulch Power)
SLGS_RJ
SLGT
(Solomon Gulch SPWY Junction)
(Solomon Gulch TWL)
SLGINS_RJ
G (Solomon ulch INS Junc)
S_SINK
(Source_Sink)
ALSO
(Allison Lake Inflow)
ALSR
(Allison Lake)
SSTAL
Allison Lake Spill)
ALSSPWY_RJ
(Allison SPWY TWL)
A_SINK
(Source_Sink)
ALLO
(Allison Reservoir Inflow)
ALLR
(Allison Reservoir)
ALLS
(Allison Reservoir Spill)
ALLS_RJ
(Allison SPW Y Junc)
S_SINK
(Source_Sink)
Hatch Acres Corporation
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
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Figure 3.3
AUTO Vista Model Elements: Alt 3c and Alt 3d
SLGQ ALSQ
(Solomon Gulch Inflow)
(Allison Lake
\ A A Inflow)
SLGR ALSR
(Solomon Gulch Reservoi ALSP (Allison Lake)
SINS SLGS (Allison Lake ALSS
lomon Power) Allison Lake S ill
( (Solomon Gulch Spill) ( Spill)
SLGP Instrea Ti Flow)
(Solomon Gulch Power)
ALST ALSSPVVYRJ
SLGT d
(Allison Lake TWL) (Allison SPWV TWL)
(Solomon Gulch TW L)
SLGINS RJ
S_SINK (Solomon Gulch INSJunc) A_SINK
(Sou rce_Sin k) (Source Sink)
3.3 Hydrology
The hydrology used for the AUTO Vista model is based on the work done by the COE in 1982 as
part of their evaluation of the potential project configurations for maximizing the Allison Lake
resource. The correlations developed from that study results in a 39-year period of average daily
flows from 1950 through 1989. The annual inflow for each of the 39 years is shown on Figure 3.4.
Figure 3.4
Allison Lake Annual Inflow, 1951 -1989
55,000
_ 50,000
45,000
Q
3 40,000
O
35,000
7
C
C
Q 30,000
O
~ 25,000
♦-
♦...............................4.,..
• ..............0..................
...............
♦
l
20,000
1950 1955 1960 1965 1970 1975 1980 1985 1990
Year
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A statistical analysis of this period of record was performed to establish a representative smaller
group of 7 years for use within the present AUTO Vista. The set of 7 years was chosen on the basis
of balancing the wet to dry conditions of annual inflow to the two basins. The specific years chosen
are indicated by the large red dots in Figure 3.4 and the associated representative inflow conditions
are summarized in Table 3.2.
Table 3.2
AUTO Vista Hydrologic Years
Total Inflow
Year Percentile Acre -Feet 3.4 Reservoir Characteristics
1969 10% 28,900
1984 25% 30,800 The minimum and maximum reservoir elevations
1954 25% 30,900 and storage characteristics for the Solomon Gulch
1961 50% 33,200 Reservoir were taken from the existing
1957 75% 36,100 information for the project as included in the
1977 75% 37,900
1989 90% 42,800 Supplemental Technical Information document as
Average 34,400 prepared in support of the FERC Part 12 Safety
Inspection process for the project.
In the case of Allison Lake, stage relationships were taken from the previously referenced COE and
HDR studies as appropriate for Alt 1b, Alt 3c and 3d. The available storage relationships, however,
were found through a recent study as performed by the Northern Arizona University as part of a
research of the receding of glaciers. The image taken from the web site that includes a description
and photographs of the research program and the resulting reservoir storage relationships are shown
on Figure 3.5.
Figure 3.5
Allison Lake Reservoir Storage
peM (m)
0.10
U0-30
0 cone Sire
1t10 m
1,450
1,400
1,350
w 1,300 — —
a
w 1,250
i
1,200
1,150
1,100
0
Alternatives 3a and 3b
Storaee - 12.100 Ac-Ft
,l
\ Alternative 3c
Stones - 13,780 Ac-Ft
`Alternatives 1, Ib and 2
Stones . 19,500 Ac-Ft
5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000
Storage (Acre -Ft)
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
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3.5 Hydro Equipment Characteristics
The performance curves for the Solomon Gulch Powerhouse have been included as provided by the
CVEA. The new units at the proposed Allison Lake Powerhouse for Alt 3c and 3d are based on
Hatch Acres in-house generic data for Pelton units. Alt 3c comprises a 4 MW generating station and
Alt 3d comprises a 6 MW generating station. A plot of the characteristics used in this analysis is
shown in Figure 3.6.
Figure 3.6
Allison Powerhouse Unit Characteristics — 4 MW Installed Capacity
100% � 5.0
so% -Efficiency 4.5
60% 4.0
70% 3.5
e 60% 3.0
5 0 % Power 00,2.5
m
40% ru
2.0
30% 1.5
20% -- — 1.0
10% 0.5
0% 0.0
0 10 20 Discharg40 50 60
e (cfs)
All elements of the conduit system components for each alternative have been assumed to perform in
accordance with published engineering data.
Figure 3.7
Allison Powerhouse Unit Characteristics — 6 MW Installed Capacity
100%
90x
00%
70%
6"
rg Z
50%
a
W 40%
Sox
20%
10%
0%
0
10 20 30 40 50 60 70 so
Discharge )ds)
Hatch Acres Corporation
70
60
5.0
40
30 s
20
10
00
90
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Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
Final Feasibility Report
3.6 AUTO Vista Results
Representative plots of the annual operation of the Solomon Lake and Allison Lake Reservoirs are
included in Appendix D.1. The two primary observations from these plots for Alt 1 are that this
alternative attempts to conserve the storage in the Solomon Gulch Reservoir as long as possible and
that the Solomon Gulch Powerhouse is slightly undersized. In the case of Alt 2 and Alt 3, the plots
suggest a parallel operation of the two basins and demonstrate a reasonable balance between
reservoir storage and powerhouse capacity.
In addition, stacked bar charts indicating the most efficient dispatch of system resources as required
to meet the system load are included in Appendix D.2 for the existing condition, Alt 1b, Alt 3c and
Alt 3d. The first charts compare the existing condition to the development alternatives for the 1961
water year, which is the 50% year as indicated in Table 3.2. Also included for comparative purposes
are the charts for 1954 and 1977 water years which represent 25% and 75% water years
respectively. Finally, a chart is included that expands the scale to show a typical weekly dispatch
from 1961.
The annual generation for each of the 7 years included in the analysis for the existing condition and
the Alt 1b, Alt 3c and Alt 3d cases are shown in Table 3.3 through Table 3.6 below.
Table 3.3
Annual Generation - Existing Condition
Generation (MWh)
Year
SG 1
SG 2
Allison
Diesel
Cogen
Total
1969
32,500
19,700
NA
11,200
22,900
86,400
1984
34,100
22,000
NA
7,500
22,800
86,400
1954
31,400
22,700
NA
9,300
23,000
86,400
1961
34,800
23,500
NA
6,800
21,300
86,400
1957
35,200
24,800
NA
6,200
20,200
86,400
1977
36,500
25,300
NA
3,400
21,100
86,400
1989
35,200
26,700
NA
4,800
19,700
86,400
Average 34,200 23,500 NA 7,000 21,600 86,400
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Table 3.4
Annual Generation -Alt 1 b
Generation (MWh)
Year
SG 1
SG2
Allison
Diesel
Cogen
Total
1969
40,700
22,400
N/A
3,300
19,900
86,400
1984
41,000
25,400
N/A
1,100
18,900
86,400
1954
39,900
22,600
N/A
3,600
20,300
86,400
1961
40,900
24,800
N/A
800
19,800
86,400
1957
40,100
23,300
N/A
3,000
20,100
86,400
1977
41,500
26,300
N/A
100
18,500
86,400
1989
39,100
27,600
N/A
2,800
16,900
86,400
Average
40,500
24,600
N/A
2,100
19,200
86,400
Table 3.5
Annual Generation - Alt 3c
Generation (MWh)
Year
SG 1
SG2
Allison
Diesel
Cogen
Total
1969
351200
19,000
25,900
1,200
5,000
86,400
1984
351900
19,600
25,800
800
4,300
86,400
1954
331400
17,100
25,800
600
9,500
86,400
1961
351700
16,200
28,400
500
5,600
86,400
1957
35,100
16,100
26,800
2,800
5,600
86,400
1977
361800
16,200
29,700
300
3,400
86,400
1989
351600
17,400
27,900
500
4,900
86,400
Average
35,400
17,400
27,200
1,000
5,500
86,400
Table 3.6
Annual Generation
- Alt 3d
Generation (M II)
Year
SG 1
SG2
Allison
Diesel
Cogen
Total
1969
35,100
11,100
26,900
1,400
11,900
86,500
1984
361300
10,800
27,300
900
11,100
86,400
1954
351600
8,500
24,900
600
16,700
86,400
1961
367600
8,700
28,200
300
12,700
86,500
1957
351600
8,200
28,200
1,600
12,800
86,400
1977
351100
11,500
29,200
400
10,300
86,400
1989
35,800
8,200
30,000
400
12,000
86,400
Average
35,700
9,600
27,800
800
12,500
86,400
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The annual general benefits from the AUTO Vista Analyses for Alt 1b, Alt 3c and Alt 3d can then be
summarized as shown in Table 3.7 in terms of the incremental hydropower generation and
associated reduction on thermal power as required to satisfy the system load for each of the
alternatives under consideration. Please note that the minor differences between the hydro and
thermal generation values for each alternative are due to rounding within the AUTO Vista modeling.
Table 3.7
Annual Generation Benefits
Generation (MWh)
Existing
Alt lb
Alt 3c
Alt 3d
Hydro 57,700
65,100
80,000
73,100
Fossil 28,600
21,300
6,500
13,300
Total 86,300
86,400
86,500
86,500
Benefit N/A
7,300
22,100
15,200
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4. Project Construction Cost and Construction Schedule
Construction costs and schedules were prepared and reported for the various upgrade configurations
under consideration for the Project during the Pre -Feasibility Study and the Interim Feasibility
Review. As stated at the close of Section 1, the focus of this Final Feasibility Report includes Alt 1b,
Alt 3c and Alt 3d as discussed below.
4.1 Construction Cost Estimates
All cost estimates are based on January 2010 bid price levels. The Direct Construction cost for each
alternative is the total of all costs directly chargeable to the construction of the project and in essence
represents a contractor's bid. Indirect costs are defined as those which are added to the Direct
Construction Cost to result in the Total Construction Cost.
The cost estimates for the heavy civil elements of the project are based on a bottoms up approach
that consider crew sizes, equipment requirements and production rates. Details for these estimates
are included in Appendix E. The costs for the major equipment within the powerhouse are based on
preliminary quotations from equipment suppliers while the cost for other lower cost items were
obtained from in-house cost data and from recently obtained bid prices on similar construction.
Indirect costs include an allowance for contingencies, engineering and owner administration. The
contingency used for all alternatives was 25%. Engineering and Owner Administration assumed for
all alternatives was 15% of construction cost, inclusive of contingencies.
The period of time required to complete the process for obtaining a FERC License can be expected to
be approximately 3 years. Adding another 2+ years to construct the project over three construction
seasons suggests that a realistic on-line date of the project to be in the range of 2015. Accordingly, it
is appropriate to include escalation to the above costs to determine a realistic on-line cost for the
project. However, for the purposes of the present economic analyses, 2010 dollars are used herein
to avoid the need to hypothesize what the cost of thermal generation may be that far into the future.
The resulting construction cost estimates for Alt 1b, Alt 3c and Alt 3d are summarized in Tables
4.1.1 and 4.1.2.
Table 4.1.1
Alternative 1 b
Total Construction Cost (Bid 1/2010)
Item
Alt 1b
Diversion to
Solomon Gulch
1. Mobilization & Access Road
$7,500,000
2. Intake Structure/ Lake Tap / Dike
$1,275 000
3. Tunnel
$20,000,000
4. Energy Dissipater
$500 000
Direct Construction Cost (Bid 1/08)
$29,275,000
Escalation
$1,183,000
Direct Construction Cost (Bid 1/10)
$30,458,000
Conti ngencies
$7,615, 000
Engineering & Owner Admin.
$5,711,000
Total Construction Cost (Bid 1/10)
$42,601,000
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Table 4.1.2
Alternatives 3c and 3d
Total Construction Cost (Bid 112010)
Alt 3c
Alt 3d
Item Allison Dam
a El 1420
Allison Dam a El 1395
1. Mobilization
$1,573,000
$1,573,000
2. Construction Access Road
$4,860,000
$4,860,000
3. Dam, Intake & Spillwaylntake
a. Embankment & Intake $19,569,000
$11,844,000
b. Spillway
$2,299,000
$2,299,000
$21,868,000
$14,143,000
4. Surface Penstock / Pipeline
a. HDPE Pipeline
$668,000
$888,000
b. Steel Pipeline
$4,201,000
$4,591,000
$4,869,000
$5,479,000
5. Powerhouse
a. Civil Works
$1,611,000
$1,779,000
b. Turbine & Generator
$2,804,000
$3,095,000
c. Misc. Mech. Equip.
$414,000
$447,000
d. Accessory Elec. Equip.
$630,000
$696,000
e. Bridge Crane
$187,000
$219,000
$5,646,000
$6,236,000
6. Switchyard
$525,000
$525,000
7. Transm. & Interconnection
$310.000
310 000
Direct Construction Cost (Bid 1/09)
$39,651,000
$33,126,000
Escalation
-$1,5 77,000
-$1,24 7,000
Direct Construction Cost (Bid 1/10)
$38,074,000
$31,879,000
Contingencies
$10,234,000
$8,635,000
Engineering & Owner Admin.
$7,250,000
$6,080,000
Total Construction Cost (Bid IA0)
$57,135,000
$47,841,000
4.2 Construction Schedule
I II ie construction of the project is controlled by the following major factors:
• Delivery time for major powerhouse equipment
• Construction quantities for the primary civil features
• Access to Allison Lake for construction activity
• Four month window for construction activity at All ison Lake
Taking these factors into consideration, the overall schedule for Alt 1b would be controlled by the
time to mine the tunnel, whereas the construction of the dam would control the schedule for either
Alt 3c or Alt 3d.
A similar approach has been used to develop a schedule for each alterative relative to the purposes
of the cost estimates presented above and the annual costs presented below for each alternative. The
schedule for Alt 3c is presented in Figure 4.1 as an example thereof.
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Figure 4.1
Alternative 3c
rnnQfrurfinn Sr_hedule
lst Season
2nd Season
3rd Season
Month 1 Month 2 Month 3 Month 4
Month 1 Month 2 Month 3 Month 4
Month 1 Month 2 Month 3 Month 4
Excavate
core trench Dewater well points
III Reservoir
Blaze trail to dam
7 8
Snow — — — —
-- —— —— ------
Pioneer Road
Embankment
1
Remmal
Embankment El.1,420
I S' Stripping to El.1 365
_
_1 to
2 '� `y / 6
ihlh
Access road to 90+00
7,000`yngle
single shift100'
/ day — single ship 1Divers
spillwayComplete
D' Penstock:
Complete Penstock:Access
to owerhouse
r bE to creek— —
1,J
creek to thrust block100'
, day 5
OLa
down areas • werhouse
2,4Penstock: HDrust blocO
Powerhouse foundation re
O
i Turbine
Penstock, PH to
Warehouses / offices
Trail �� inlet valve
thrust block
Powerhouse
Switch and
Transmission Line
JL Housing: Man -Camp in Valdez
Housing: Man -Camp in Valdez
Housing: Construction Camp Dam She
On Activity Duration (weeks)
4.3 Economic Analysis
The Total Investment cost includes interest during construction (IDC) over an assumed 28-month
construction period. As outlined above, we have assumed that construction at the project site would
come to a stop during the winter months, with the exception of equipment installation within the
powerhouse structure.
Annual costs of the Project can be apportioned into fixed and variable costs. For this analysis, the
fixed amount, amortization of the Total Capital Requirements less earnings on Reserves, is based on
7% interest rate financing over a 30-year term. Variable annual costs escalate each year and include
operation and maintenance (O&M) costs, administrative and general expenses, interim replacements
and insurance. The basic assumptions for determining the annual fixed and variable costs of the
Project are shown in Table 4.2. The development of the annual cost as well as the resulting unit cost
of power for each of the alternative development schemes considered herein are shown in 2010
dollars on Table 4.3.
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Table 4.2
Basic Assumptions for Economic Analyses
Item Value
Construction Period 28 months
Financing Term
30 years
Financing Interest Rate
7%
Reinvestment Rate
Same as financing
Escalation of Project Costs
3% annually
Financing Reserve
1 year of debt service
Financing Expenses
3% of Total Investment Cost
Variable Annual Costs
$500,000
Table 4.3
First Year Cost of Power (2010 dollars)
Item
Alt 1b
Diversion to SC
Alt 3c
Allison Dam @ El. 1420
Alt 3d
Allison Dam @ El. 1395
Total Construction Cost (Bid IA0)
$42,601,000
$57,135,000
$47,841,000
Interest During Construction
3,280,000
5,166.000
4,316.000
Total Investment Cost
$45,881,000
$62,301,000
$52,157,000
Reserve Fund
4,151,000
5,633,000
4,717,000
Financing & Legal
1,380,000
1,870,000
1,560,000
Working Capital
100,000
100,000
100,000
Total Capital Requirements (1/10)
$51,512,000
$69,904,000
$58,534,000
Annual Cost
Debt Service
$4,151,000
$5,633,000
$4,717,000
Earnings on Reserve Fund
(291,000)
(394,000)
(330,000)
Variable Annual Costs
500,000
500.000
500.00
Total First -Year Annual Cost
$4,360,000
$5,739,000
$4,887,000
Added Hydro Generation (kWh)
7,235,000
22,137,000
15,277,000
First -Year Cost of Power ($/kWh)
$0.60
$0.26
$0.32
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Final Feasibility Report
5. Regulatory Considerations and Environmental Field Investigations
CVEA filed an Application for Preliminary Permit on March 3, 2008, for FERC Project No. 13124.
That Application included a detailed study plan based on consultations that began in 2007. There
was a competing application filed by Green Power LLC; however, CVEA's application was deemed
to be first filed. FERC issued the Permit to CVEA on September 4, 2008, effective September 1, 2008
and expiring on August 31, 2011. Prior to award of the Preliminary Permit, in May 2008 CVEA
commenced consultations with the resource agencies to discuss the study plan presented in the
Application for Preliminary Permit and began its initial engineering and environmental field
investigations.
As provided by the FERC regulation, "the purpose of the preliminary permit is to provide a three-year
period during which time CVEA maintains priority to file an application for license while studies are
conducted and an application for license is prepared."
The FERC pre -filing process, including the environmental and engineering studies and investigations,
has been conducted with the goal in mind that CVEA intends to file an application for license with
the FERC in January 2011. To date field and office studies have been performed by CVEA's Project
Team including: Hatch Acres Corporation, R&M Consultants, Alaska Biological Resources, Inc.
(ABR), and Northern Land Use Resources, Inc. (NLUR). Field and office reports prepared by CVEA's
Project Team have been prepared to document the 2008 & 2009 effort. These studies and reports
support this Final Feasibility Report as well as the Application for License. A summary of CVEA's
regulatory and environmental framework is presented below.
5.1 Regulatory Considerations
Early in the pre -filing process CVEA considered the three potential pre -filing options:
The Integrated Licensing Process (ILP), the default process at the FERC. This process
essentially puts FERC in the "driver's seat" and establishes hard deadlines at the outset of the
pre -filing process. These deadlines do not address the difficulties with developing projects
in Alaska, for example (1) unforgiving deadlines that do not take into consideration
difficulties with accessing the site to perform studies; (2) the need to use helicopter access to
conduct studies and the problems with weather interruptions; and (3) the fact that resource
agencies are in the field much of the summer and early fall and therefore unavailable to
work with an applicant under the strict deadlines regarding consultation.
The Alternative Licensing Procedure (ALP), the preferred option elected by CVEA and an
application to use the ALP is pending before the FERC. The ALP enables an Applicant to
design a pre -filing process in consultation with the federal and state agencies to address the
above noted problems with the ILP. Under the ALP, CVEA can prepare the Environmental
Exhibit in the format of a document that addresses the requirements of the National
Environmental Policy Act (NEPA) in the form of a Preliminary Draft Environmental
Assessment (PDEA) as discussed below.
The Traditional Licensing Process (TLP). This pre -filing process would not enable CVEA to
prepare its draft NEPA document in the form of the PDEA and would expose CVEA to a
longer process, providing resource agencies with essentially "two bites at the apple" to
recommend conditions in the License and resulting in a higher cost to CVEA with no
positive results to CVEA.
As noted above, CVEA at the outset of the process elected to use the ALP and met with FERC in June
2009 to discuss the path forward. CVEA is now awaiting FERC approval of its request.
Hatch Acres Corporation Page 38
Copper Valley Electric Association, Inc. - Allison Lake Hydroelectric Project
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Throughout the pre -filing process, CVEA has diligently consulted with FERC Staff and representatives
from Federal and State agencies regarding the proposed project and has completed two years of field
and office studies. Some of these studies are currently ongoing.
The regulatory accomplishments and milestones are listed below:
• Application for Preliminary Permit to study the Allison Lake Project was filed March 3, 2008.
This was a competitive proceeding and CVEA prevailed by being first in line to file as Rural
Electric Cooperatives do not enjoy municipal preference'.
• FERC initiated consultations with federal and state agencies on May 14, 2008, and these
consultations will continue throughout the term of the Preliminary Permit. The purpose of
these consultations is three fold: to discuss CVEA's proposed project; to discuss and receive
approval regarding necessary field studies; and to discuss potential project related effects
and potential Protection, Mitigation, and Enhancement (PM&E) measures that may be
included in the FERC License.
• Consultation held with Alaska Department of Natural Resources regarding water rights held
in May 2008; ADNR provided documentation of the permit issued to Alyeska Pipeline
Service Company (ADNR file LAS 11813)
• CVEA's consultants met with FERC Staff in April 2008 to discuss on a generic basis the issues
associated with conducting studies and preparing Applications for License for projects
located in Alaska.
• CVEA received access licenses from Alyeska to enable the Project Team to enter Alyeska
lands to conduct studies beginning in June 2008
• Alaska Department of Fish & Game (ADF&G) issued Fish Sampling Permit #08-198 in
August 2008
• FERC issued Order Issuing Preliminary Permit on September 4, 2008; the Permit will expire
on August 31, 2011
• CVEA prepared a Literature Review and Gap Analysis regarding Allison Lake in 2008 to
assist in identifying required studies.
• CVEA prepared study plans in consultation with the Federal and State resource agencies
beginning in May 2008 and has completed two years of field and office studies as noted in
this Final Feasibility Report.
• CVEA met with FERC Staff in Washington, DC, in June 2009 to discuss the Project and its
interest in using the ALP. FERC Staff agreed that CVEA's proposal made sense and in light of
the fact that CVEA would have two years of studies completed that the required Pre -
Application Document (PAD) could be presented to include: Draft Exhibit A describing the
Project layout and operation and other information required by the regulation (18 CFR 4.61);
a Preliminary Draft Environmental Assessment; and supporting data including conies of field
reports. v V
• CVEA prepared an initial Contact List in 2008 and issued its Contact List and Regulatory
Schedule for the FERC Proceeding on January 15, 2010 for review and comment.
• CVEA provided its Notice of Intent to File an Original License Application (NOI) and its
Request to the FERC to use the Alternative Licensing Procedure (ALP), including the
Communications Protocol, to the entities included in the Contact List on January 15, 2010.
• CVEA filed its request to be designated as the Non -Federal Representative to conduct
informal consultation with the Fish and Wildlife Service (FWS) and the National Marine
Fisheries Service (NMFS) to engage in consultation regarding Section 7 of the Endangered
Species Act (ESA); to engage in consultation with NMFS regarding Section 305 of the
' Rural Electric Cooperatives, Investor Owned Utilities and Independent Power Producers are all grouped into one
category. Only municipal and state applicants enjoy preference under Section 7(a) of the Federal Power Act.
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Magnuson Stevens Act; and the Alaska State Historic Preservation Officer (SHPO) pursuant
to Section 106 of the National Historic Preservation Act (NHPA) on January 26, 2010.
• CVEA filed its NOI and Request to Use the ALP with the FERC on April 7, 2010
• CVEA prepared and filed its Preliminary Application Document (PAD) comprised of: Exhibit
A — Project Description; the Preliminary Draft Environmental Assessment (PDEA); and copies
of Field Studies Reports with the FERC and provided to entities included in the Contact List
on April 13, 2010
• FERC approved of the request to consult with the SHPO on April 19, 2010; and, on April 22,
2010, FERC approved of the request to consult with the FWS and NMFS regarding Section 7
of the ESA and NMFS regarding Section 305 of the Magnuson Stevens Act.
• CVEA prepared and filed Scoping Document with FERC and resources agencies on April 22,
2010
• CVEA will conduct NEPA scoping meetings on May 10, 2010, in Anchorage and May 12,
2010 in Valdez.
• CVEA proposes to provide its Draft Application for License for review and comment to
entities listed on the Contact List on July 30, 2010.
• CVEA proposes to file its Final Application for License with the FERC and provide copies to
the entities listed on the Contact List in January 2011.
• The Preliminary Permit expires on August 31, 2011.
5.2 Environmental Field Investigations
In support of the preliminary permit, environmental field investigations began in 2008 for the
Project. These field investigations and desk -top reviews are summarized in the following sections
and the complete reports can be found in Appendix F. The major studies conducted are listed in
Table 5.1.
Table 5.1
Summary of Major Environmental Studies Conducted
Type of Field Investigation Conducted By Timeline
Geological Resources R&M Consultants Began: 2008
(As described in Section 2) Completed: 2009
Water Use and Quality R&M Consultants Began: 2008
Completed: on -going
Biological Resources
- Fish and Aquatic Resources
- Vegetation ABR Inc. Began: 2008
- Wetlands Completed: on -going
- Birds and Mammals
- Wildlife Habitats
Archaeological/Historical NLUR, Inc. Began: 2008Completed: on -going
5.2.1 Water Quality Study
5.2.2 Description
A Water Quality Study was undertaken by R&M Consultants, Inc. (R&M) as a subconsultant to Hatch
Acres to describe the hydrologic setting of the Allison Lake Watershed. This study, included herein
as Appendix FA, sought to describe and quantify the flow variations in Allison Creek and to
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characterize the Allison Lake/Allison Creek water quality. To that end, studies of the Allison Lake
Watershed began in summer of 2008 and will proceed throughout the 36-month life of the
Preliminary Permit, as required to help determine the feasibility of this project. The following three
objectives were pursued:
• Perform monthly, opportunistic in -situ monitoring of pH, temperature, specific conductivity,
and turbidity in two locations of Allison Creek,
• Continuously monitor stream temperature in two locations of Allison Creek, and
• Annually model the thermal profile of Allison Lake
As Allison Lake hydropower development continues to be studied, its potential impacts to water
quality may be assessed against environmental baseline data. The rationale for this effort comes from
the fact that FERC and State agencies require at least two consecutive years of water quality data to
support a Development Application. The two-year data set is stipulated to illustrate variations from
season to season and year to year. As such, water quality monitoring has continued through 2009 on
a regular basis, the results of which are included in the full report.
Physical and chemical parameters such as dissolved oxygen (DO), total dissolved gas, total hardness,
chlorophyll, total nitrogen, total phosphorus and fecal coliform concentrations have not been
acquired. Based on agency consultation, DO has been specifically excluded as a parameter of
concern.
5.2.3 Findings
Indications to date are that water quality is relatively consistent between upper and lower Allison
Creek. Stream temperatures have followed generally expected trends of peaking in July, then
beginning a cooling trend in August that continues through the fall months to bottom out in
November. Daily temperature variations in Allison Creek tend to decrease markedly beginning in
early September, likely coinciding with shorter, cooler days. Daily variations begin to increase
noticeably in June when the snow melt becomes prevalent during daytime hours.
Available data indicate that specific conductivity is either equivalent between the upper and lower
reaches of Allison Creek or ranges slightly higher in lower Allison Creek. The higher readings in the
lower creek could be a result of the increased sediment load in the lower reaches of the stream after
traversing a mountainside and receiving side input from multiple drainages. Ongoing data collection
continues to more clearly define this trend.
Turbidity levels in lower Allison Creek tend to range slightly lower than those measured in the upper
ream o uie stream. This trend contradicts the indications described in the previous edition of this
report (R&M, 2009). At the time that the previous report was published as a final version in April
2009, insufficient data had been collected to illustrate the inconsistency of turbidity readings
collected in September and October of 2008. When viewed against the backdrop of subsequent
turbidity readings, the September/October 2008 readings appear anomalously high. Based on this
fact and on the obvious turbidity sensor malfunction experienced by the field personnel on 8
October 2008, the September/October 2008 turbidity readings are considered suspect. As such, they
should only be used for modeling and/or regulatory purposes with caution, if at all. Excluding these
readings from analysis leaves a clear trend to date of slightly higher measured turbidity in upper
Allison Creek than in lower Allison Creek.
Seasonally, turbidity measurements to date in the creek tend to range highest in August; this is
expected, and is likely due to peak flows during that month (R&M, 2010). Turbidity is not an
inherent property of water as is pH or temperature (Davies -Colley and Smith, 2001), and so it can be
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a useful indicator of the environmental health of a water body. Within the context of this study, it
will be important to compare the potential effects of hydropower development at Allison Lake on
turbidity within Allison Creek. Significant changes in this water characteristic as a result of
development could be detrimental to the ecology of Allison Creek and its ability to support aquatic
life. Additional study of the turbidity levels within Allison Creek will help to establish an adequate
environmental baseline against which the potential effects of future hydropower development can be
measured.
5.3 Biological Resources
5.3.1 Literature Review and Gap Analysis
In support of the permitting process for the Allison Lake Hydroelectric project the Hatch Acres team
jointly conducted a review of the published literature and unpublished research reports on biological
resources in the project area and subsequently prepared a gap analysis thereof. The goal of the
analysis was to identify biological resources for which additional field studies may be required. The
report that was prepared includes basic background information on life histories of fish and wildlife,
a brief listing and summary of studies directly applicable to resources in the project area, and an
assessment of gaps in current knowledge of resources in the project area. The analysis addressed fish
and macro invertebrates, mammals, birds, vegetation, wetlands, and wildlife habitats. Field studies
conducted in 2009 were pursued to help fill the identified data gaps. The results of the field studies
are outlined in the section below.
5.3.2 Description of Study
Following the above described gap analysis, Alaska Biological Resources, Inc. (ABR) prepared a
report, Biological Resources in the Allison Lake Hydroelectric Project Area: 2009 Studies and Impact
Analysis, as a subconsultant to Hatch Acres in support of the FERC permitting process. This report,
which is included herein as Appendix F.2, discusses the field studies conducted in 2009 to address
the data gaps as identified in the above Literature Review and Gap Analysis section and report issued
in 2008. The report summarizes available relevant information, including results of 2009 studies, for
terrestrial mammal, bird, and fish species in the impact assessment area and, for those species
identified as conservation priorities, presents a semi -quantitative, habitat -based assessment of
potential impacts of the Allison Lake project. The report also addresses potentially affected
vegetation, wetlands and wildlife habitats. The impact assessment area boundaries were defined as
the assumed maximal distance of potential impact for any wildlife or fish species, resulting in
inclusion of the entire upper and lower Allison Creek basin within about 1 mile of Allison Lake and
the coastal portion of the Solomon Gulch drainage west of Solomon Gulch Creek. Marine habitats
were excluded as not affected by the Allison Lake project.
5.3.3 Findings
Nearly all of Alaska's birds are protected under provisions of the Migratory Bird Treaty Act (MBTA).
The only species exempt from the 'no -take' provisions of the MBTA are introduced and invasive
species, such as Starlings in Alaska. Bald and Golden eagles and their nests are further protected by
the Bald and Golden Eagle Protection Act. The Endangered Species Act (ESA) protects all listed and
candidate threatened or endangered species, as defined by the U.S. Fish and Wildlife Service
(USFWS) and the National Marine Fisheries Service (NMFS). In Alaska, Kittlitz's Murrelet is a
candidate species for listing under the ESA (USFWS 2007a) and, on 2 October 2008, the USFWS
announced that the Marbled Murrelet also is under review for listing. Eight additional bird species
that are confirmed in the project area are considered high -priority species for conservation in Alaska.
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Although not federally listed or candidate threatened or endangered, these species are of increasing
concern because of low and/or declining populations or other population threats. These species of
conservation concern are likely to occur in terrestrial and freshwater habitats in the project area
during the breeding, migration, and/or wintering seasons.
Although few of the fish or mammal species likely to occur in the Allison Lake project area are
considered priority species for conservation because of population declines or threats, most fish and
many mammal species are of considerable conservation interest, largely because of their use in
subsistence and/or recreational activities. The mountain goat, however, is considered a management
indicator species by the U.S. Forest Service (USFS) and mountain goat habitats on USFS lands can be
removed from logging plans. Other mammals also are of conservation interest to management
agencies, largely due to the regulation of human harvest activities, such as sport hunting, trapping,
and subsistence activities, which are managed by the Alaska Department of Fish and Game (ADFG).
Similarly, freshwater habitats for fish are protected by many state and federal water -quality and
fisheries -habitat regulations. Because of their importance in commercial, sport, and subsistence
harvest, anadromous fish (salmon and some trout populations) are of particular conservation interest
and development activities that could potentially affect anadromous fish streams are highly regulated
by ADFG and NMFS. For a full discussion of the field studies results please reference the attached
appendix.
5.4 Recreation and Land Use
Situated near Prince William Sound, the Project site is located on the opposite side of the sound due
south of Valdez, Alaska. Valdez's proximity to the sound and Chugach Mountains provides many
recreational opportunities. Recreational use near Valdez and the surrounding areas include: fishing,
kayaking, canoeing, rafting, motor boating, sailing, hiking, skiing and cross-country skiing,
snowshoeing, dog sledding, ice climbing, snow mobiling, biking, camping, and hunting. There are
no water recreational facilities such as a boat dock at Allison Lake. The Project area is undeveloped.
The closest facilities to the Project site include the Alyeska Pipeline Service Company (northeast of
the Project site) and the Solomon Gulch Hydroelectric Project (due east of the Project site).
There are no current and future recreation needs near the Project site as identified in Alaska's State
Comprehensive Outdoor Recreation Plan (2009, Irwin). There will be no future recreation
constructed at the Project site. The access road to the Project site will remain restricted to CVEA
personnel use only. These measures have been taken due to the Project site's proximity to the
Alyeska Pipeline Service Company and Trans -Alaskan Pipeline. Signs will direct readers east to the
Solomon Gulch Trail and Solomon Gulch Hydroelectric Project. Enhancement measures at the
Solomon Gulch viewing area may be implemented to supplement additional activity to the area.
5.5 Archaeological / Historical Study
5.5.1 Description of Study
In order to assess the cultural, archaeological and historical character of the Project site, an extensive
research program was undertaken by Northern Land Use Research, Inc. (NLUR) as a subconsultant
Hatch Acres. The results of this study, included herein as Appendix F.3, are summarized below.
Cultural resources information available for Alaska resides in numerous sources, varies in quality
and availability, and presents a sometimes daunting challenge for researchers to identify, locate, and
summarize during the preparation of literature reviews such as the present report. Several articles in
the Alaska Journal of Anthropology recently reviewed cultural resources research and anthropology
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research in Alaska over the last 30 years. All of these articles provided excellent reviews of several
decades of recent research within particular sub -fields of anthropology. None of these sources
identify research in Valdez Arm in general, or the Allison Lake vicinity specifically.
Cultural resource investigation reports from every community in Alaska are stored at the Alaska
Department of Natural Resources, Division of Parks and Outdoor Recreation, Office of History and
Archaeology (ADNR, DOPOR, OHA)— the State Historic Preservation Office (SHPO), in Anchorage.
Previous research is often in the unpublished literature for a particular community. To identify these
sources, it is common practice to locate a recent report, and then to examine the bibliography for
references to earlier works. This "data mining" research methodology is necessary when so many of
the source materials are unpublished, narrowly circulated, and ephemeral reports.
Published and unpublished sources of information pertaining to the cultural resources were
examined within and adjacent to the project area. NLUR's in-house files and reports were checked
for information relevant to Allison Lake. NLUR also searched the electronic card catalogs of the
Alaska Resources Library and Information Services (ARLIS), UAA/APU Consortium Library, Loussac
Public Library, Anchorage Museum at Rasmuson Center (AMRC), and the University of Alaska
Fairbanks Library electronic card catalog "GOLDMINE". In addition, NLUR reviewed the U.S.
survey plats for homesteads and Fort Liscum located within and adjacent to the project area (website
accessed various dates, 2009, http://landrecords.alaska.gov).
5.5.2 Findings
There are no sites in the vicinity of the project area listed on the National Register of Historic Places.
The cleanup efforts following the Exxon Valdez Oil Spill (EVOS) included numerous cultural
resources research studies (Mobley et al. 1990; Restoration Planning Work Group 1990; L.
Yarborough 1997 and references therein). Post-EVOS research on subsistence included reports on
specific communities, specific species or species groups, and long-term studies of the EVOS effects
on subsistence (for example Fall et al. 1996; Picou et al. 2009; Fogarty et al. 2000; Simeone 2008;
Fall 2009 and references therein).
The research results show that a total of four sites are known in the vicinity of the Allison Lake
Hydroelectric project. Two of them, VAL-00054, Midas Camp and VAL-00093 Solomon Dam are
within the Solomon Gulch hydroelectric project area and should not be affected by the Allison Lake
project, if the sites still even exist. VAL-00055, Fort Liscum (Dayville) reportedly was completely
demolished during the construction of the Alyeska marine terminal facility in the 1970s. It is
possible that some features relating to the Fort and subsequent homesteading and cannery operations
exist in upland areas. VAL-00090 Granby Roadhouse is listed in the AHRS on the basis of its
presence on a 1923 National Geographic map (Smith 1974:67). Granby Roadhouse has never been
field verified as to its location or condition.
The Alyeska marine terminal and TAPS pipeline are not listed in the AHRS. The TAPS pipeline
crosses Allison Creek.
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6. Conclusions and Recommendations
6.1 Conclusions
6.1.1 Engineering Studies
The conclusion gained from the engineering studies performed as a part of the present evaluation
include:
• The Project is technically feasible.
• Of those technically feasible arrangements considered, Alt 3c consisting of a buried / surface
penstock with a dam constructed to El 1420 appears to provide the lowest cost of power.
• The Project will fit well into the existing CVEA power system and will substantially reduce
the amount of thermal generation that is required to meet system load.
• The technical challenges of the Allison Lake site add considerable cost of the Project.
• The Project would benefit from state or federal financial support.
6.1.2 Regulatory and Environmental Studies
The conclusion gained from the regulatory and environment studies performed as a part of the
present evaluation include:
• Allison Lake does not support fish; there were no fish found during field studies
• The powerhouse would be located above the identified anadromous fish barrier in Allison
Creek.
• Salmonids observed at the mouth of Allison Creek were determined to be strays from the
hatchery located at the Solomon Gulch Project. No wild fish were observed during the two
years of studies.
• Water quality is relatively consistent between upper and lower Allison Creek. CVEA will
develop plans to protect water quality during construction.
• No habitats used by murrelets would be directly affected by the Project. The limited
activities in the upper basin near the dam and upper, penstock during project operation are
anticipated to have no impacts on nesting murrelets.
• With appropriate restrictions of helicopter traffic, impacts related to behavioral disturbance
of mountain goats should be minor or moderate during project construction.
• Access to lower Allison Creek is restricted by Alyeska. Informal use of the upper areas of
Allison Creek for purposes of recreation does occur, however, due to the proximity to the
Marine Terminal of the TAPS, no formal recreational facilities are proposed.
• The Project does not include any federal lands.
• The Project is not located within or adjacent to a National Wild and Scenic River, State -
protected river segment, or designated Wilderness Area.
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6.2 Recommendations
Based on the conclusions outlined above, CVEA would be well served to undertake the following:
• Proceed with the development of a FERC License Application for the Project based on Alt 3c
to be submitted at the earliest possible date, but not later than, August 31, 2011 as follows:
- As the designated non-federal representative to conduct informal endangered
species consultation and Magnuson -Stevens Fishery Conservation and Management
Act consultation, enter into consultation with the U.S. Fish and Wildlife Service and
National Marine Fisheries Service to verify that the project would not affect
protected species and identify any recommended measures to avoid any future
effects
- As the designated non-federal representative to conduct informal consultation with
the State Historic Preservation Officer (SHPO) regarding Section 106 of the National
Historic Preservation Act., conduct the survey recommended by the SHPO in the
second quarter of 2010
- Hold NEPA Scoping Meetings in May 2010 for purposes of discussing the Project
and engaging the resource agencies and public in discussion of any potential
project -effects
- Develop any required protection, mitigation, and enhancement measures following
the Scoping Meetings
• Include the following mitigation / enhancement measures in the FERC License Application:
- A return flow outlet at the proposed dam to provide an ecological release to Allison
Creek
- A kiosk along Dayville Road to explain the Allison Lake Project and direct people to
the Solomon Gulch Project for recreational activities
- Proposed recreation facilities consistent with the needs of the area and practicable
opportunities as provided by the Project.
• Support efforts to reclassify hydropower as "renewable" with reference to Federal grants and
CREB financing
• Pursue other sources of funding at State level
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7. References
1. HDR Engineering, Inc., Allison Lake Reconnaissance Study, prepared for Alaska Energy
Authority, September 1992.
2. US Army Corps of Engineers, Electric Power for Valdez and the Copper River Basin, Interim
Feasibility Report and Final Environmental Impact Statement, March 1981.
3. Schiff, Caleb. Thesis: "Late -Holocene temperature of Prince William Sound, Southern
Alaska." 2006. Northern Arizona University.
<http://oak.ucc.nau.edu/cis235/AlaskaClimate/allison.html >
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