HomeMy WebLinkAbout161215-False-Pass-Hydro-feasibility-progress-report-low-rezaPolarconsult & Living Systems DesignFalse Pass Hydro Feasibility: 20161125
False Pass Hydroelectric Potential at
Unga Man Creek
2016 Feasibility Study Progress Report
Prepared for the City of False Pass &
The Aleutian Pribilof Islands Community Development Association (APICDA)
by: Joel Groves of Polarconsult & Bob Christensen of Living Systems Design
20161215
Cover 2. Stream gage at Unga Man Creek bridge
Cover 1. Unga Man Creek seen from north valley wall
iPolarconsult & Living Systems DesignFalse Pass Hydro Feasibility: 20161125
List of Figures .......................................................................................................ii
Executive Summary ............................................................................................iii
Background ..........................................................................................................1
Introduction ......................................................................................................................................................1
False Pass, Alaska .............................................................................................................................................1
Current Electrical Generation ......................................................................................................................2
Previous Reports .............................................................................................................................................3
Unga Man Creek...................................................................................................4
Location & Land Status..................................................................................................................................4
Geology ..............................................................................................................................................................4
Hydrology ..........................................................................................................................................................5
Topography & Vegetation ............................................................................................................................6
Fish & Wildlife ...................................................................................................................................................8
Preliminary Design ............................................................................................10
Hydropower Resource Considered ..........................................................................................................10
General Project Considerations .................................................................................................................11
Description of Preferred Project Configuration ...................................................................................12
Conclusion ..........................................................................................................16
Summary ...........................................................................................................................................................16
Recommendations ........................................................................................................................................17
TABLE OF CONTENTS
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Cover 1. Unga Man Creek seen from north valley wall .......................................................................a
Cover 2. Stream gage at Unga Man Creek bridge ................................................................................a
Executive Summary 1. Typical aerial of Unga man Creek braid taken from drone ..................iv
Figure 1. The community of False Pass is located on Unimak Island. ............................................1
Figure 2. Google Earth view of the False Pass Village. ........................................................................1
Figure 3. Summary of utility statistics ......................................................................................................2
Figure 4. Drone’s eye view of Bering Pacific Seafoods plant. ...........................................................2
Figure 5. General land status near False Pass, AK. ................................................................................4
Figure 6. False Pass area geology. ..............................................................................................................4
Figure 7. Stream gage installation locations. ........................................................................................5
Figure 8 New logger installed in upper reaches of Unga Man Creek ...........................................5
Figure 9. Flow records for Unga Man Creek and Russell Creek basins ..........................................6
Figure 10. Panoramic photo of the upper reaches of Unga Man Creek .......................................6
Figure 11. Terrain and ortho imagery data collected via drone in 2016 field trip. .....................7
Figure 12. Draft Vegetation Classification draped over digital surface model ...........................8
Figure 13. Salmon foot count graph. .......................................................................................................8
Figure 14. Dominant substrates by reach. ..............................................................................................9
Figure 15. Example gravel and cobble mix from lower reach. .........................................................9
Figure 16. Example cobble and boulder mix from middle reach. ..................................................9
Figure 17. Example boulder and cobble mix from upper reaches. ................................................9
Figure 18. Setting minnow traps for resident & juvenile fish .........................................................10
Figure 19. Study area ....................................................................................................................................10
Figure 20. Estimated design parameters. ...............................................................................................13
Figure 21. Recommended project configuration ................................................................................14
LIST OF FIGURES
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EXECUTIVE SUMMARY
This Feasibility Study Progress Report provides an update on the resource data collection, analysis,
and preliminary findings to date for hydropower development potential at Unga Man Creek for the
community of False Pass. Since the Reconnaissance Study was issued in fall 2015, the following
has occurred:
• Conducted additional fish surveys at Unga Man Creek in 2016 to continue building record of
anadromous and resident fish presence and abundance,
• Conducted additional fish habitat surveys to define extent and quality of fish habitat at Unga
Man Creek,
• Collected aerial imagery and developed a digital surface model of Unga Man valley topography
to better understand vegetation and topography in the project area,
• Collected one year of hydrology data at the bridge stream gauging station installed in August
2015, and,
• Installed two new stream gauging stations on the north and south fork to refine upper basin
hydrology.
This new resource data has been analyzed to further evaluate the feasibility of a hydro project at
Unga Man Creek. Current analysis has produced the following preliminary findings.
1. Fish habitat surveys indicate productive anadromous (predominantly pink salmon) habitat
in the lower ¼ mile of Unga Man Creek, downstream of the proposed powerhouse location.
Surveyed habitat conditions upstream of this reach are poorly suited to salmon spawning due
to the larger (predominately cobble and boulder) substrate size and highly unstable stream
bed.
2. Review of aerial imagery of the project area indicates wetlands are limited to a few isolated
areas that can be largely avoided by project development. These aerial interpretations
should be confirmed by ground surveys during the design and permitting phase of project
development.
3. There is a correlation between flows at Unga Man Creek and Russell Creek at Cold Bay. The
correlation was of moderate quality (R2 of 0.47 for the one year of data) but good enough to
build a refined long-term hydrology model for Unga Man Creek. That model indicates Unga
Man hydrology is a bit less favorable than the ‘no-data’ estimates generated in 2015 and
used for the Reconnaissance Report. Given that weather in the 2015-16 year was unusual, it
remains uncertain how the basin correlation and hydrology model may change as we collect
more data.
4. Current economic analysis using the new hydrology model indicates a 140 kW hydro can
provide about 75% of annual utility load, lower than the 84% estimated in the Reconnaissance
Study. This estimate is expected to continue fluctuating as our understanding of Unga Man
hydrology improves with additional data.
5. Estimated benefit-cost ratio decreased from 1.8 in the Reconnaissance Study to 1.4 with
current data, mainly due to the refined hydrology and resulting decreased project performance.
6. We started to look at project sizing, and increased installed capacity from 125 kW to 140
kW to better carry existing utility load. Recommended installed capacity is still subject to
revision with future data and analysis.
7. Field observations and initial analysis confirmed the cost estimate methodology in the
Reconnaissance Study is still valid. The estimated construction cost increased to $4.6 million
(probable range of $3.6 to 5.4 million) due to the increase in installed capacity.
8. We took a preliminary look at dispatchable loads (interruptible heating loads) in the community
that could be served by unused hydro capacity. Analysis indicates that 30 to 40 percent of
annual heating loads at six public buildings could be served by excess hydro capacity (by
a 140 kW project). A larger 180 kW hydro project could supply 50 to 60 percent of these
heating loads on a dispatchable basis. Future analysis may indicate a larger installed capacity
is justified.
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9. Combined average annual fuel savings (power plant + dispatched heat loads) is estimated at
45,700 gallons annually for a 140 kW hydro project.
10. We reviewed a range of project configurations throughout the basin and the general layout
developed in the Reconnaissance Report (a project on the main stem of Unga Man Creek)
appears to be the most economic. Moving higher up in the basin trades less flow for more
head with slight degradation of resultant performance (less annual energy for a given
installed capacity) but higher cost mainly due to longer access trails through more difficult
terrain. Overall, these project configurations appear to be economically inferior due to slightly
decreased performance and increased cost.
11. If ADFG in-stream flow requirements are higher than our current assumptions, this could
reverse the above conclusion, with north fork- or south fork-only project configurations
possibly being preferred over a main-stem configuration because they preserve the other fork
for habitat flow. Development of the north fork is probably better than the south fork due to
easier access, but this determination would depend on hydrology from the gauges installed
this year and interpretation of site conditions above the limits of 2016 foot surveys.
Based on the above findings, we recommend that feasibility analysis for this project continue. Key
elements of the recommended 2017 Work Plan are:
1. Continue stream gauging with existing gauges.
2. Continue fisheries studies. Next steps are to consult with ADFG area biologist, then ADFG
habitat division to review creek resource value and project. ADFG feedback will help guide
the scope / direction of future fisheries studies and project evaluation.
3. Continue analysis as additional data is collected and analyzed. Characterize potential
dispatched heat loads, update hydrology model with additional data, consider fish habitat
requirements in project layout and size. Finalize layout and capacity, finalize feasibility-level
project cost estimate and economics, prepare final report.
4. Start long-lead permit actions. Enough data now exists to file a FERC declaration of intention,
which will define the permitting process (FERC vs non-FERC) for the project. Existing
information indicates it should be non-FERC.
Executive Summary 1. Typical aerial of Unga man Creek braid taken from drone
Page 1Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
BACKGROUND
INTRODUCTION
Polarconsult Alaska, Inc. (Polarconsult) and Living Systems Design, LLC (LSD) were contracted by
the City of False Pass (City) and The Aleutian Pribilof Islands Community Development Association
(APICDA) to conduct feasibility investigations for hydropower development on Unga Man Creek
near False Pass, Alaska. A field trip that included City and APICDA staff was conducted August 15
to 19, 2016 to assess technical and environmental conditions at Unga Man Creek and install stream
gages at key points in the Unga Man basin. This report summarizes information gathered during
this field trip along with additional research conducted for feasibility analysis.
The current effort builds on the out-
come of a reconnaissance study com-
pleted by LSD in 2015 and prior stud-
ies listed in Section 1.3, that identified
Unga Man Creek as the preferred hy-
dropower resource for the community.
Feasibility investigations conducted in
2016 focused on collecting resource
data that will be used to refine the
project configuration, performance,
environmental impacts, permitting re-
quirements, and cost.
FALSE PASS, ALASKA
The community of False Pass is located
on Unimak Island at the eastern edge
of the Aleutian island chain (54°49′40″N 163°23′57″W), just across Isanotski Strait from the Alas-
ka Peninsula (Fig. 1). It is an isolated coastal village that is only accessible by boat and plane (pri-
marily via the community of Cold Bay).
The landscape surrounding the com-
munity is mountainous and spectacu-
lar in its beauty with the Bering Sea
to the North and the Gulf of Alaska to
the South (Fig. 2). The climate is sub-
polar maritime with cool summers and
relatively mild winters. Annual precipi-
tation averages around 30 inches with
3-5 feet of snow in the winter. Wind
and fog are common. Sea ice has been
known to extend into the area in colder
winters.
There are approximately 50 year round
residents who live in False Pass. Most
residents participate in the commercial
and subsistence fishing economies to
some degree. These folks are joined in
the summer months by approximately 60 part-time residents who are employed at the APICDA
fish processing plant. Other employment opportunities include local government, the school and a
variety of services.
Figure 2. Google Earth view of the False Pass Village.
Airport Village
Harbor
Fish
Plant
Roundtop Mt.
Unga Man
Valley
Ferry
Dock
Figure 1. The community of False Pass is located on Unimak Is-
land on the Aleutian Island chain.
False Pass
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CURRENT ELECTRICAL GENERATION
Electricity service in the community of False Pass is provided by the City of False Pass, which op-
erates a certificated electric utility authorized by Certificate of Public Convenience and Necessity
No. 442 issued by the Alaska Public Utilities Commission (now Regulatory Commission of Alaska) in
1993. The utility operates an isolated electric grid in the village, generating electricity with diesel
generators (125 kilowatts (kW), 175 kW and 180 kW units available depending on load). The village
load averages around 70 kW at generation, for total annual generation of approximately 600,000
kilowatt-hours (kWh). Summary utility statistics are presented in Figure 3.
APICDA subsidiary Bering Pacific Seafoods
(BPS) operates a fish processing plant in
False Pass. The plant self-generates elec-
tricity with diesel generators (1,250 kW,
365 kW, 350 kW and 350 kW units are in-
stalled). The plant’s average load in 2016
was approximately 385 kW, and peak load
was approximately 850 kW. BPS is consid-
ering plant modifications which may alter
the plant’s electric demand.
Electricity cost in False Pass is high by most
standards, ranging between 40 to 50 cents
per kWh in recent years. However, this is
lower than in many small rural Alaska com-
munities, where electric rates of 50 to 80
cents per kWh (and higher) are common.
Figure 3. Summary of utility statistics
Figure 4. Drone’s eye view of Unga Man Creek Bridge and
road back to Bering Pacific Seafoods plant.
Fish Plant
Unga Man Creek
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The utility distribution system takes electricity generated at 480 volts three-phase in the diesel
powerhouse and increases the voltage to 7.2/12.47 kV for distribution. The distribution system is
underground, and is three phase out to the BPS fish plant. The existing distribution system ex-
tends to the crab pot storage yard just north of the BPS plant.
PREVIOUS REPORTS
The community of False Pass has been
actively seeking alternative energy solu-
tions to provide greater energy security
to the community and reduce the costs
of energy to its residents and businesses.
Hydropower has been noted in most of
the reports as potentially feasible. Both
wind and tidal have also been looked
at and have received mixed reviews in
terms of feasibility thus far. Five reports
were reviewed as part of this feasibility
assessment:
• A report was written in 1982 that
described hydroelectric generation
opportunities near False Pass as
not economically feasible. This
is not surprising given that the
cost of diesel at that time was a
little over one dollar per gallon.
(Reconnaissance Study of Energy
Requirements and Alternatives,
1982)
• A more in depth report from 2010
(Hereinafter “The Baker report”)
looked at a number of communities
in the area and summarized
options for wind, tidal and hydro
in False Pass. Recommendations
from this report were to prioritize
wind and hydro first because these
technologies are more mature and
straightforward in terms of operation and maintenance. For hydro, two creeks were looked
at: Unga Man Creek and Waterfall Creek. Both sites were noted by the authors as worth
further investigation with an emphasis on establishing an annual record of flow to determine
economic feasibility. (Renewable Energy Resource Assessment for the Communities of Cold
Bay, False Pass, and Nelson Lagoon, 2014)
• An AEA memo dated February 17, 2015 was reviewed that looked at two design options in the
Unga Man Creek watershed. The author used gaging data from Russell Creek in nearby Cold
Bay to estimate energy availability for two Unga Man Creek options at capable of providing
140-150 kW. It was recommended to develop a flow record and assess aquatic habitat for this
system as the next logical step in reconnaissance. (False Pass Hydro Review, February 2015).
• An initial study of wind energy was reported on in July of 2015. This report confirmed
observations in previous reconnaissance work on wind power for False Pass and concluded
that the wind resource is difficult to exploit because of local turbulence. (False Pass Wind
Energy Feasibility Report, 2015).
• A hydro reconnaissance study for False Pass completed by LSD in 2015. This study reviewed
the potential of Unga Man Creek and Waterfall Creek and concluded that Unga Man Creek was
a better option for the community and recommended continued study.
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UNGA MAN CREEK
LOCATION & LAND STATUS
Unga Man Creek flows to saltwater 1.2 miles north
of the community False Pass, just before the ter-
minus of the northern portion of the community
road system. The majority of the watershed is
owned by the Isanotski Corporation, with the up-
permost portions managed by the Aleutians Pen-
insula National Wildlife Refuge. The lower reaches
of the creek are easily accessible via the road sys-
tem, including a bridge which provides access to
the community dump just north of the creek.
GEOLOGY
The Unga Man Creek valley is mapped as Alluvi-
al Deposits in the valley bottom and Quaternary
Volcanics extending from the valley wall to the sur-
rounding peaks (see figure 5). The main-stem and
primary tributaries remain active alluvial chan-
nels today. Substrate between the lower extent of
our survey (beginning in the intertidal zone) and
including approximately 3.33 miles upstream in-
cluded sand, gravel, cobble and boulder. Reaches
downstream of the bridge were dominated by a
mixture of cobbles and gravels with intermittent
pockets of sand. The reaches from the bridge to
the primary fork were dominated by a mixture of
cobble sand boulders with intermittent pockets
of gravel. The reaches upstream of the fork were
dominated by a mixture of boulders and cobbles with rare pockets of gravel (see Figure 17). Prob-
able bedrock was observed only at a single location in the survey reach, at a cut bank where the
current creek meander is eroding the valley sidewall. This exposure was at River Mile (RM) 1.33
(river-right). Exposed rock appeared to be weak, with loose rock readily decomposing into clayey
material. Other cut banks at RM 1.0 (river-right) and RM 1.67 (river-left) appear to be layered ash
deposits that are holding vertical faces approximately 10 feet tall.
Based on observations, bedrock depth beneath
alluvial deposits along the surveyed reach is ex-
pected to be variable, and at many areas may
be too deep to economically found the diversion
structure. If encountered, bedrock is expected
to be relatively weak, with a preliminary estimate
of allowable bearing pressure at 2,000 pounds
per square foot and lateral friction coefficient of
0.25. Based on observations, conceptual design
of a diversion structure in the surveyed reach
should be based on a footing founded in alluvium
or weak rock with the above preliminary design
values. These preliminary design values will need
to be updated once a specific project configura-
tion is selected and a site-specific geotechnical
investigation completed.Figure 6. False Pass area geology.
Unga Man
Figure 5. General land status near False Pass, AK.
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HYDROLOGY
Unga Man Creek has an east-facing basin area of
3.79 square miles. The eastern perimeter of the
basin is formed by the coast and lowlands along
Isanotski Strait, and the north, south, and west
perimeters of the basin are predominantly moun-
tain peaks and ridges with elevations ranging
from approximately 2,000 to 2,800 feet, with the
highest peaks along the western perimeter. The
USGS quad map for the area published in 1995
indicates that some alpine areas of the basin were
once glaciated, but glaciers were either much di-
minished or non-existent in August 2016.
The City and APICDA recognize the importance of
establishing an empirical record of flow for Unga
Man Creek as a critical step in determining hydro-
power feasibility and upon their initiative we in-
stalled two stream gages to begin that process in
2015. The first site was located just downstream
of the bridge that crosses Unga Man Creek (RM
0.61) and the second site was located approxi-
mately 0.14 miles upstream of the bridge site (RM
0.75) (see figure 7). The logger at the bridge site
has been providing a stable record of flow since
its installation, however, the logger upstream of
the bridge failed during a high flow event during
the winter of 2015-16.
During the August 2016 field trip we removed
the hardware from the failed logger and used the
parts for installing two more loggers approximately 1 mile upstream of the bridge, just beyond the
primary fork in the main stem of the creek (see figure 7). The upstream loggers, both at RM 1.65,
will allow for an assessment of the unique hydrology of the two primary basins contributing to the
total flow of Unga Man Creek. For example, although the individual basin areas in the headwaters
of Unga Man Creek are similar in size, because of their different aspects (NE vs SE) it is possible
that the southern basin holds snow for longer pe-
riods of time and thus contributes more flow dur-
ing the mid-summer time period.
Site selection for gaging stations was fairly chal-
lenging again this year because of the lack of
bedrock along the surveyed channel length and
the limited availability of stable pool features.
The size of the substrate within the channel and
the bank full width of the creek both indicate that
annual flows are high at times. Large boulders
were used for anchoring each gage (See figure
8). Stainless Hobo Water Loggers were installed
in stilling wells along with staff gages in a similar
fashion to last year except for the new bluetooth
data download features of the loggers used at
the upstream gage sites. Each station includes
its own barometric correction. City of False Pass
Figure 8 New logger installed in upper reaches of
Unga Man Creek - North Tributary.
Figure 7. Stream gage installation locations.
Page 6Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
and VPSO staff were trained in wa-
ter logger data download as well
as using the Global Water Systems
flow probe for manual discharge
measurements and they will be do-
ing the fieldwork necessary to es-
tablish a rating curve for interpret-
ing the water logger data.
Hydrology data collected from Au-
gust 2015 to August 2016 at the
bridge gauging station was ana-
lyzed and compared to the long-
term hydrology record at Russell
Creek in Cold Bay. The concurrent
period of record shows a clear cor-
relation between the two basins,
with a coefficient of determination
(R 2) of 0.47. R 2 for the fall and win -
ter season (October 2015 to March
2016) was much higher at 0.79, and R 2 for the spring and summer season was much lower at 0.17.
The period of record at Unga Man Creek is not yet long enough to draw firm conclusions about sea-
sonal relationships between these two basins, but the correlation is sufficient to refine the hydrol-
ogy model and make more educated estimates about the long-term hydrology at Unga Man Creek.
Based on the available record, it appears Unga Man Creek is “flashier” than Russell Creek, which
is expected given that the Unga Man basin is 1/10th the size of the Russell Creek basin. Figure 9
shows the concurrent flow record for both basins. The actual flow has been divided by the respec-
tive basin areas to aid in visual comparison. The detailed hydrology analysis and description of the
hydrology study efforts to date is presented in Attachment 1.
TOPOGRAPHY & VEGETATION
Topographic and land cover data available for the Unga Man Creek watershed has been very coarse
to date. Our team collected low elevation aerial photography in order to develop fine-scaled topo-
graphic and vegetation data for project design.
Figure 10. Panoramic photo of the upper reaches of Unga Man Creek; North fork at right, South fork at left.
Figure 9. Flow records for Unga Man Creek and Russell Creek basins
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The digital surface model shown in figure 11 indicates a total difference in elevation from mean
high tide to the upper reaches of the potential project area of approximately 400 feet. The gradient
of the stream is relatively consistent from saltwater to the bridge at an average of 2%. From the
bridge upstream to the main fork the grade averages 3.5%. Upstream of the main fork the grade
increases a fair bit with an average of 9.5% in the south fork and 7.5% in the north fork up to the
end of the 2016 survey area.
The slopes leading to the stream channel are mostly gentle with fairly low cut banks except in a
few locations. The topography becomes significantly more rugged upstream of the main fork, es-
pecially in the south fork valley.
Vegetation in the project area is dominated by shrub thickets that are comprised mostly of elder-
berry, alder and willow in the tall category and salmonberry and devil’s club in the medium cat-
egory (Figure 12). Patches of herbaceous meadow and wet meadow occur in a few locations near
the beach and where finer substrates have accumulated from past alluvial activity. Meadow plants
include cow parsnip, fireweed, lupine, shooting star, aster and a variety of graminoid species.
Figure 11. Terrain and ortho imagery data collected via drone in 2016 field trip.
Page 8Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
FISH & WILDLIFE
Since the field work conducted for the 2015 recon-
naissance study, Unga Man Creek has been nomi-
nated for inclusion in Alaska’s Anadromous Waters
Catalog (AWC). It is widely recognized that the 2015
pink salmon run was one of the largest on record so
we decided to conduct more thorough surveys of fish
use of Unga Man Creek to look closer at its anadromy.
The False Pass VPSO was trained to conduct salm-
on “foot counts” from the bridge to the primary fork
in Unga Man Creek (the purple reach in Figure 13).
Foot counts were performed from mid July to early
September. The final survey was to be performed in
mid-September but high flows prohibited access. Pink
Salmon began to show up in Unga Man Creek in early-
August with a peak presence observed in late-August throughout the length of the surveyed reach.
Sockeye and Chum salmon were also observed in these reaches during this time period but no
adult Coho salmon. See the chart in Figure 14 for a summary of data collected.
Figure 12. Draft Vegetation Classification draped over digital surface model.
Figure 13. Salmon foot count graph.
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During the field visit in August we conducted more detailed surveys of Unga Man Creek fish habi-
tat. The creek was walked from the intertidal zone up to the new logger installations located just
upstream of the primary fork in the creek. Geotagged photos were taken along the stream length
to document dominant substrate sizes by reach and provide a general assessment of salmon
spawning habitat suitability in Unga Man Creek.
The majority of stream surveyed was poorly suited to salmon spawning because most reaches were
dominated by mixtures of cobble and boulder (see Figures 14-17). Pink salmon were observed ac-
tively digging redds in the lowermost reaches, just upstream of the intertidal zone, where the gra-
dients were suitable to deposition of gravel patches of 10-100 square meters. The reaches above
the bridge rarely had patches of more than a single square meter, and most of these patches are
likely very unstable. It is possible that some of these smaller patches are suitable for Dolly Varden.
The presence of Sockeye is a somewhat mysterious as the watershed does not include a lake and
what spawning gravels there are seem to be most suited to pink salmon and concentrated near
the intertidal reaches. There have been documented cases in Alaska of Sockeye spawning in very
large riverine systems and in marine beaches but these are relatively rare. It is most likely that
Sockeye observed in Unga Man Creek are strays from nearby lake systems (e.g. Hungry’s Creek
Figure 15. Example gravel and
cobble mix from lower reach.
Figure 14. Dominant substrates by reach.
Figure 16. Example cobble and
boulder mix from middle reach.
Figure 17. Example boulder and
cobble mix from upper reaches.
Page 10Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
and Otter Point Creek).
During the August field visit we also set 10 min-
now traps baited with salmon eggs in pool habitat
upstream and downstream of the Unga Man Creek
bridge. One trap was damaged by a bear and caught
no fish. In the remaining 9 traps, 132 Dolly Varden
were caught that ranged in size from 5-18 cm. Ad-
ditionally, 2 Coho fry were caught in two separate
traps and they measured 8 cm and 7 cm. The pres-
ence of Coho fry is also somewhat mysterious as
no adults have been documented in the stream.
These fry may be nomads from a nearby spawning
stream, which according to the AWC is in Cold Bay.
Bear sign was observed along the stream indicat-
ing some predation on salmon occurs. A variety of
other birds and mammals likely use the area as for-
aging and cover habitat.
Although impacts to fish and wildlife habitat from construction and operation of a hydropower facil-
ity on Unga Man Creek would be unavoidable, it is likely that a sound design could largely mitigate
these impacts. Additional field surveys and collaboration with the relevant agencies will be critical
to balancing the costs and benefits of such mitigatory actions and will be an important contributing
factor in determining the overall feasibility of hydropower development for False Pass.
PRELIMINARY DESIGN
HYDROPOWER RESOURCE CONSIDERED
The reach of Unga Man Creek that is under study
for hydro project development extends from tide-
water upstream to RM 2.8 on the south fork, RM
2.1 on the north fork, and RM 2.1 on the east fork
(Figure 19). Upstream of these three points, the
major tributaries branch off into several smaller
alpine tributaries which are deemed impractical
for hydropower development.
The feasibility analysis reviewed several hydro
project configurations within the study reach of
Unga Man Creek and its major tributaries to de-
termine which configurations appear to be most
feasible, and which appear to not be feasible.
Analysis indicates that projects located in the low-
er portions (below RM 2.2 on the north and south
forks) of the drainage basin will be more economi-
cally feasible than projects in the upper portions
of the basin. This is generally due to the following
reasons:
• Upper basin projects require longer access
roads / trails through more difficult terrain
than lower basin projects. These longer
access routes may increase cost to the point
that upper basin projects are significantly
more expensive than lower basin alternatives.
Figure 18. Setting minnow traps for resident & ju-
venile fish in Unga Man Creek pools.
Figure 19. Study area
Page 11Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
• While upper basin projects have more elevation drop than lower basin projects, they also
have less basin area and water flow. At Unga Man Creek, available information indicates the
increased elevation does not quite compensate for the decreased water flow, so upper basin
projects will have a lower plant capacity factor and will not produce as much energy as lower
basin projects for a given installed capacity.
The combination of higher cost and decreased performance makes upper basin project configura-
tions less economically feasible than lower basin configurations.
GENERAL PROJECT CONSIDERATIONS
Dispatchable Electric Loads
When a run-of-river hydro has more generating capacity than the utility load, the excess hydro
output can be dispatched to interruptible heating loads (such as building or water heating sys-
tems) to displace heating fuel. Public or commercial buildings are typically fitted with dispatched
electric services because the cost of the dedicated meter, controls, wiring, and mechanical system
upgrades usually exceeds the benefits for smaller buildings such as houses.
Buildings in False Pass that could be appropriate for dispatchable electric service include:
• False Pass School
• Bering Pacific Seafoods complex
• Library / Post Office
• City Office / Recreation Center
• Public Safety / Clinic Building
• City shop
The heating loads and suitability of these buildings to receive dispatchable electric services have
not been reviewed at this time. To form a preliminary estimate of the value of dispatchable energy
services for initial project analysis, the monthly heating load of these six buildings was estimated
based on their general size and climate data for nearby Cold Bay, Alaska.
Preliminary analysis indicates excess energy from a 140 kW hydro project could provide approxi-
mately 30 to 40 percent of the annual heating needs of the six buildings listed above. Excess
energy from a 180 kW hydro project could provide approximately 50 to 60 percent of the annual
heating needs of these buildings.
Installed Capacity
Selecting the installed generating capacity of a hydro project is a key part of the feasibility and
design process. Key criteria that must be considered in selecting an installed capacity follow:
• Hydro projects are long life (50+ year) assets. The project’s installed capacity should consider
both current and reasonably likely future load growth.
• The most cost-effective time to add capacity or plan for future capacity increases is during
original permitting, design and construction. It is significantly more costly to implement
capacity upgrades after the fact as many components (intake, penstock, turbine, generator,
transformer, etc.) are capacity-specific and must be replaced or duplicated rather than
expanded or upgraded.
• The hydrology of the water resource must also be well-understood and considered. More
generating capacity is useless if there is no water to drive it.
• An under-sized project can be a lost opportunity for the community, as the incremental cost
of more capacity at the time of original construction is typically modest compared with the
overall project cost or future upgrade cost.
• An over-sized project can become a burden on a utility, as it may saddle the utility with excessive
capital debt, operating / maintenance costs, and may operate at decreased efficiency.
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The current analysis included preliminary review of projects with capacity ranging from 100 to
200 kW. Approximately 140 kW or larger was found to maximize the percentage of existing utility
load that is supplied by the hydro plant. Smaller project capacities supply less of the utility load
because peak load exceeds their generating capacity, forcing the diesel plant to parallel with the
hydro. Larger project capacities supply a similar percentage of utility load as the 140 kW project
as performance of larger projects is constrained by water availability.
Dispatchable electric loads are another factor to be considered in selecting the installed capacity,
and as feasibility analysis continues the optimal installed capacity may change from the 140 kW
project described in this progress report.
DESCRIPTION OF PREFERRED PROJECT CONFIGURATION
Overview
Preliminary feasibility analysis has identified a 140 kW run-of-river hydro project configuration fea-
turing a diversion between RM 1.4 and RM 1.6 and a powerhouse near RM 0.15, east (downstream)
of the community dump. Estimated technical parameters and project performance for this layout
are summarized in Figure 20. Descriptions of the major project components follow.
Access
Project access would start near the end of the existing landfill access road, and is shown on Figure
21. The existing road would be extended along the west and north perimeter of the landfill, con-
tinuing downhill past the landfill to the hydro powerhouse site. The diversion access route would
start at the northwest corner of the landfill and continue up the north side of the Unga Man Creek
valley to the diversion site.
Available data suggests that the conditions along the route may be relatively straightforward for
road or trail construction. The route has maximum slopes of 15% and maximum cross slopes of
20 to 50% depending on exact routing.
The diversion access route crosses several minor tributaries. These can be crossed either with
appropriately-sized culverts or engineered fording locations. Since these minor tributaries ascend
steep (25%+) alpine slopes upstream of the trail route, fish passage upstream of the trail route is
not expected to be a design consideration for these crossings.
Diversion and Intake
Two water diversion and intake sites on the main stem of Unga Man Creek warrant consideration.
The upstream diversion site is at RM 1.6 and 260 feet above sea level (ASL), immediately down-
stream of the confluence of the north and south forks of Unga Man Creek. This site would maxi-
mize head for a main stem project. Unga Man Creek’s approximately 40-foot wide active meander
at this site is pinned against the north valley wall and incised approximately 15 to 20 feet into the
broader valley floor. Bedrock is not visible at this location.
The downstream site is at RM 1.4 and 220 feet ASL, immediately downstream of the confluence of
the east fork and main stem of Unga Man Creek. Compared to the upstream diversion site, this
site is approximately 40 feet lower in elevation but because it captures the east fork is expected
to have approximately 20 to 25 percent more flow. The downstream site is in the middle of the
valley floor, in a reach where Unga Man Creek has an approximately 120-foot wide active meander
zone that is transiting across the valley floor from the north side at RM 1.5 to the south side at RM
1.35. Bedrock is not visible at this location.
At the current level of study, both diversion sites appear to have similar technical and design con-
siderations and both project configurations have similar performance and economics. Additional
Page 13Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
factors which may influence diversion site selection include whether anadromous fish passage
through the diversion structure is required, the need for in-stream flow reservations for fish habi-
tat downstream of the structure, and site-specific geotechnical conditions.
At either site, the diversion structure may consist of an approximately 100 to 150-foot long by ap-
proximately 8 to 12-foot tall concrete wall founded in alluvium at a depth beneath the maximum
scour, with a stepped spillway to direct normal and flood flows into the downstream creek channel.
The creek channel at the spillway would be armored with a rip-rap apron sized to prevent scour.
In the floodplain area to either side of the spillway, the wall would be buttressed on upstream and
downstream sides by earth fill and capped with riprap for erosion control.
Figure 20. Estimated design parameters remain subject to change as the feasibility study investigations and
analysis continue.
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Figure 21. Recommended project configuration
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An automatic bypass gate would be built into the main diversion wall. This gate is normally closed
and is programmed to automatically open during high water events to allow sediment to flush out
of the impoundment and provide downstream gravel recruitment.
The water intake would be a coanda-type inclined screen built onto the downstream edge of the
main spillway. Water would flow over the spillway and onto this screen. Project water would fall
through the screen into a collection gallery and thence into the penstock. Excess flow would run
off the end of the screen and into the creek downstream of the diversion.
It is expected that this diversion scheme would meet the requirements of the Fishway Act (Alaska
Statute (AS) 16.05.841) by preventing admittance of fish into the project works yet allowing fish
to pass downstream when flow was sufficient.
If the permitting process determines that the diversion structure is required to comply with the
Anadromous Fish Act (AS 16.05.871), a fish ladder would be required to admit anadromous fish
upstream through the diversion structure. Compliance with AS 16.05.871 is also expected to re-
quire an in-stream flow reservation through the project bypass reach.
Penstock
The penstock would be buried in the access road/trail to the diversion site. The penstock would be
a 24-inch diameter pipe approximately 5,700 to 6,500 feet long depending on the specific diversion
and powerhouse sites selected. Secondary power and plant control lines would also be installed in
the access road / trail between the powerhouse and diversion sites to provide communications and
power to the diversion site. Net project operating head listed in Figure 20 assumes high-density
polyethylene pipe. Several types of pipe are suitable for this project.
Powerhouse Site
The powerhouse would be an approximately 24-foot by 24-foot building. The foundation will have
special design considerations to absorb lateral forces from the penstock, turbine, and generator,
but the general building shell would be of conventional commercial/industrial construction. It is
assumed the powerhouse can be sited with a finished floor elevation of 25 feet ASL. The specific
site would be selected that meets the following criteria:
• Upstream of confirmed anadromous fish habitat in the lowermost reaches of Unga Man Creek
(approximately RM 0.1).
• Outside areas susceptible to long-term meanders / flood hazards from Unga Man Creek.
• Suitable geotechnical conditions.
• Suitable to the land owner.
• Compatible with the nearby landfill operations and other concurrent land uses.
The powerhouse will house the turbine-generator, load bank, switchgear and controls, and asso-
ciated equipment for the project. The turbine would be a dual-admittance (1/3 – 2/3) crossflow
type turbine coupled via direct drive or speed increaser to a three phase 480-volt synchronous
generator. Switchgear and controls would allow the hydro power plant to automatically operate
in stand-alone mode or in parallel with the diesel power plant depending on water availability and
utility load.
The existing controls and switchgear in the existing diesel plant have not been evaluated to assess
their suitability for automatic operation with a hydro plant. Upgrades to the diesel plant may be
required.
After passing through the turbine, spent water would be discharged to a tailrace and returned to
Unga Man Creek. The tailrace can be a gravel and cobble-lined ditch. Some periodic maintenance
of the tailrace is expected as the main channel of Unga Man Creek meanders over time.
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Utility Extensions
Three phase 7.2 / 12.47 kV utility primary electric distribution would be extended from the exist-
ing pad-mount transformer located in the storage lot north of the Bering Pacific Seafoods plant
approximately 5,000 feet to the hydro powerhouse site. The electric extension can be installed
underground along the existing road, in conduit over the existing bridge, and underground to the
powerhouse site.
Approximately 12,000 feet of dedicated communication line is required between the diesel and
hydro powerhouses to coordinate plant operations. This can be an underground cable installed
in existing utility easements in the community and parallel to the primary power extension to the
hydro powerhouse site.
Cost Estimate
The estimated cost for the hydro project is developed in the attached project performance and
economic analysis memo (Attachment 2). The estimated construction cost is $4.6 million with a
probable range of $3.6 to $5.4 million. The cost is slightly higher than estimated in the 2015 recon-
naissance study because the installed capacity has increased from 125 kW to 140 kW.
Economic Analysis
The economic analysis of the project is presented in the attached project performance and eco-
nomic analysis (Attachment 2). Based on current data and estimates, the life-cycle benefit cost
ratio of the project is estimated to be 1.4.
The estimated benefit-cost ratio is lower than the initial estimate of 1.8 in the 2015 Reconnaissance
Study primarily because the updated hydrology data indicates lower flow in Unga Man Creek than
previously estimated. This results in decreased performance, with the hydro plant supplying an
estimated 75% of annual utility load compared with 86% estimated in the Reconnaissance Study.
CONCLUSION
SUMMARY
A 140 kW run-of-river hydro project on the main stem of Unga Man Creek appears to be a viable
option for greatly enhancing community energy security and costs. Analysis indicates lower basin
project configurations are more feasible than upper basin project configurations, and the prelimi-
nary design presented in this progress report is the preferred configuration based on available
resource data. Future resource data may alter the preferred configuration, but it is expected to
remain in the lower basin.
The estimated benefit cost ratio for the project is 1.4, with the project supplying approximate-
ly 75% of the utility’s annual electric load. Excess hydro generating capacity could be sold to
dispatchable electric services to provide approximately 35% of the annual heating load of six com-
munity buildings.
Combined average fuel savings (displaced diesel power plant and heating fuel) is estimated at
45,700 gallons annually.
This project appears compatible with fisheries resources in Unga Man Creek, as essentially all pro-
ductive anadromous habitat is located downstream of the proposed powerhouse and tailrace loca-
tion. Resident fish habitat and passage throughout the proposed bypass reach can be sustained
by high flow events and accretive flows below the diversion site. Close coordination with ADFG is
warranted to confirm these findings and define fish habitat permit requirements as soon as practi-
cal as they may have a significant impact on project cost and performance.
Page 17Polarconsult & Living Systems DesignFalse Pass Hydro Feasibility 20161125
RECOMMENDATIONS
Based on current data and analysis, the hydro project will provide significant long-term benefits to
the community of False Pass, and continued investigation is warranted. It is recommended that
the City and APICDA continue with feasibility investigations. Future work should include:
1. Continue stream gauging. One year of stream gauging data from the bridge gauging sta-
tion has been analyzed, and has confirmed that the 25-year record at Russell Creek in Cold Bay
can be used to estimate long-term hydrology trends at Unga Man Creek. Additional Unga Man
Creek data will help verify that the existing record is representative, and will help to refine and
build confidence in the relationship between the two creeks. Existing gauges at the north and
south forks of Unga Man Creek will provide flow data closer to the intake site.
2. Continue fisheries studies. Salmon were observed throughout the proposed bypass reach of
Unga Man Creek, but no spawning habitat or spawning behavior was observed in the proposed
bypass reach in 2015 or 2016. Early consultation with ADFG is recommended to coordinate on
the scope of future fisheries surveys. If the proposed bypass reach or reaches upstream of the
project are not productive fish habitat, it will benefit the community to minimize or eliminate
any in-stream flow requirements that ADFG may want on the creek.
3. Review project configuration and economics. Conduct more detailed analysis of project
configurations to finalize a preferred configuration. Project analysis using refined fisheries and
hydrology data may indicate a different configuration than what is presented in this progress
report.
4. Evaluate Dispatchable Loads. The potential load, costs, and benefits of dispatchable servic -
es should be analyzed to better quantify this opportunity and help guide selection of installed
hydro capacity.
5. Review project capacity. Current analysis indicates the 140 kW project is the smallest proj-
ect that will maximize fuel savings at the diesel power plant. Larger projects do not displace
additional fuel because hydro output is limited by water availability. Larger project capacities
would displace more heating fuel through dispatched services, which would increase project
benefits.
6. Upper Basin reconnaissance. Based on the current analysis, upper basin project configu-
rations are expected to be economically inferior to lower basin projects, and collection of ad-
ditional resource data to evaluate upper basin configurations is not recommended at this time.
7. Long-lead permit actions. Based on the favorable status of current review, it is recommend -
ed that APICDA and the City prepare and file a Declaration of Intention (DI) for the project with
the Federal Energy Regulatory Commission (FERC) to confirm the project’s non-jurisdictional
status. It normally takes FERC about 90 days to process a DI, but the process can take over
a year. There is sufficient existing information to file the DI now, and early filing will both (1)
minimize the impact of FERC delay on the project schedule and (2) provide increased certainty
with regard to the overall permitting process for the project.