HomeMy WebLinkAboutWhittier Small Hydropower Interim Reconnaissance Report 2011~
US Army Corps
of Engineers
Alaska Distric Whittier Small Hydropower Interim
Reconnaissance Report
Whittier, Alaska
U.S.ARMY CORPS OF ENGINEERS
ALASKA DISTRICT
September 2011
Table of Contents
list of Figures
List ofTables
Introduction
Whittier Climate and Hydrology
Streamflows
Estimates of Power Production
Site Selection .................. .
Upper Whittier
Lower Whittier Creek
Shakespeare
Learnard Creek
Cove Creek
ROM Cost Estimates and Issues Identified
Conclusions and Recommendations
Appendix A: Comparison of Whittier Creek to Twentymile River flows
List of Figures
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1
3
6
7
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12
... 15
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19
21
22
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Figure 1 : Location and vicinity map showing the project area (Red Circle) ................................................. 1
Figure 2: Whittier (PAWR) average maximum and minimum temperatures (1942-2010) .......................... 2
Figure 3: Whittier Creek runoff in inches for 2010 (RED) vs Inches of precipitation .................................... 3
Figure 4: Average daily flows of the extended Whittier Creek streamflow record.
Figure 5: Schematic of typical run of river small hydro electric project ..
Figure 6: Whittier Creek (extended record WY 2001-2010) flow duration
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5
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Figure 7: Hydropower Sites near Whittier evaluated in this interim reconnaissance report.. ..................... 8
Figure 8: Topographic map of the proposed Upper Whittier Creek hydroelectric site .............................. 10
Figure 9: Topographic map of the proposed Lower Whittier Creek hydroelectric site .............................. 13
Figure 10: Topo map of the proposed Shakespeare Creek hydroelectric site ............................................ 15
Figure 11: Topo map of the proposed Learnard Creek hydroelectric site .................................................. 17
Figure 12 Topographic map of the proposed Cove Creek hydroelectric site ............................................ 19
List of Tables
Table 1: Average, Maximum and Minimum monthly flows estimated for Whittier Creek using an
extended record (WY 2000-2010) ................................................................................................................ 4
Table 2: Watersheds selected for screening ................................................................................................. 7
Table 3: Upper Whittier Creek site estimates ............................................................................................. 10
Table 4: Lower Whittier Creek site estimates
Table 5: Shakespeare Creek site estimates ......................................... .
Table 6: Shakespeare Creek site estimates .............................................. .
Table 7: Cove Creek site estimates ................. .
Table 8: ROM Cost Estimates for Sites Evaluated.
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19
21
Table 9: Significant Issues Identified. .. ............................................................ 21
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Introduction
The purpose of this initial interim report is to provide a reconnaissance level screening evaluation of the
potential hydropower sites in the vicinity of Whittier, Alaska. Whittier is connected to the rail belt
electrical grid. For a project to be economically feasible, the life cyle cost to generate hydroelectric
power needs to be less than the cost to purchase power from the electric grid. At each site, the power
available, the average annual energy generated, and a rough order of magnitude capital costs were
estimated based on available data. This information was combined to determine the estimated cost of
energy generation (cents/kilowatt hour [kWh]), which was then compared with the current electrical
energy price in Whittier to determine if a small hydropower project is cost effective. A 1 day cursory
evaluation of the sites was also conducted to help estimate construction costs and environmental risks
associated with each location. The next phase of the project would include a detailed feasibility analysis
and a preliminary design should one or more alternatives warrant further investigation.
Figure 1 : Location and vicinity map showing the project area (Red Circle).
Whittier Climate and Hydrology
Whittier is located on the western edge of Prince William Sound and is surrounded on three sides by the
Chugach Mountains. The climate in Whittier is typical of a maritime location with high annual
precipitation totals and moderate temperatures. The ice-free Gulf of Alaska keeps temperatures
relatively warm during the winter. Summers are generally cool and cloudy along the coast. Figure 2
shows the average maximum and minimum temperatures based on data recorded in Whittier between
1942 and 2010. A large amount of precipitation falls each year with, on average, 207 inches of
precipitation recorded annually between 1983 and 2010. Much of this precipitation falls as snow during
the winter months. Heavy snowfalls occur as the warm, moisture-rich Pacific air is lifted over the coastal
mountains. The maximum snow depth in Whittier each winter ranges from 20 to 141 inches, with an
average maximum snow depth of 64 inches each winter. Precipitation within the watersheds examined
are much higher than those measured in the city of Whittier due to orographic and elevation effects.
1
65.----------------------------------------------------,
60
55
50
,.... 45
!;!:;.
Q) .a 40
~
Q)
c. 35 E
Q)
1-
30
25
20
15 ~------~------~------~--------~------~------~
Mar May Jul Sep Nov
Figure 2: Whittier (PAWR) average maximum and minimum temperatures (1942-2010)
A large portion of the small watersheds selected for this study are covered by glaciers. This results in an
annual hydrograph that is buffered by snowmelt and melt runoff from the glaciers. This provides a
steady supply of water even during warm clear weather during the summer months. Almost all of the
annual runoff in these small watersheds occurs during the summer months, providing steady sustained
power generation capacity for approximately one half of the year. Figure 3 compares inches of
precipitation versus inches of runoff during the water year 2009 (the only year stream gage data is
available for Whittier). Runoff exceeded the recorded precipitation in Whittier during this water year.
This is likely due to two reasons: the first being that more precipitation falls in the Whittier Creek
watershecj than is measured within the city of Whittier, and the second reason could be a result of the
glaciated portion of the watershed losing mass. As a glacier loses mass, more water is available for
runoff than falls on the glacier as precipitation.
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250
200
150
c:
100
50
o ~--.--------.-------.-------.-------.--------.-~
Nov
2009
Jan
I
Mar May Jul
2010
Sep
Figure 3: Whittier Creek runoff in inches for 2010 (RED) vs Inches of precipitation recorded in Whittier (PAWR). Orographic
increases in precipitation in the upper watershed combined with a loss of glacier mass result in more runoff than the
measure precipitation for WY2010.
Stream flows
A stream gage was installed on Whittier Creek in the fall of 2009 (USGS 15236210, See Figure 7).
Generally, at least 5 to 10 years of stream flow data is required to make meaningful decisions based on
the gage record. However, if a nearby gage correlates well with the shorter term gage record, the longer
term gage data can be used to extend the short-term record through a regression analysis.
Several concurrent stream gage records were examined and compared with the Whittier Creek record
for the water year 2010. Three nearby gages were selected for comparison: Twentymile River
(15272380L Sixmile Creek (15271000L and Wolverine Creek (15236900). The average daily flows for
both Twentymile River and Wolverine Creek correlated well for the concurrent periods of record, with a
coefficient of determination (R 2 ) of 0.81 and 0.73, respectively. Both watersheds contain a significant
percentage of glaciers and are located in a similar maritime climate zone. Based on the regression
analysis, the Twentymile gage was utilized to extend the 1-year Whittier Creek stream gage during the
summer months (May-November) for Water Years 2001-2010 (figure 4 and table 1). Based on the
annual hydrographs for Wolverine Creek and the one year of gaged data from Whittier Creek, it was
assumed that no runoff would be available for power production during the winter months between
December and April for the watersheds studied. Average flows during this time period are less than 10
cubic feet/section (cfsL with a typical baseflow of 1 to 2 cfs during this period.
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Erom the 10-year extended Whittier Creek stream record, an average daily flow duration curve was
developed with a preliminary consideration for retaining some instream flow through the reach of
stream that will be bypassed.
900
BOO
700
600
500
""' .!!!
.!::!. ~ 400
Li:
300
200
100
-0
Jan Mar May Jul Sep Nov
Figure 4: Average, maximum and minimum average daily flows of the extended Whittier Creek streamflow record utilizing a
regression analysis with Twentymlle River (WY 2001-2010).
Table 1: Average, Maximum and Minimum monthly flows estimated for Whittier Creek
using an extended record (WY 2000-2010).
Month Average Flow (CFS} Max (CFS} Min (CFS}
January 0 0.00 0.00
February 0 0.00 0.00
March 0 0.00 0.00
April 18.91 (2%} 43.12 0.09
May 87.70 (9 %} 180.85 33.54
June 179.41 (19 %} 283.36 122.65
July 221.19 (23 %} 373.42 151.35
August 196.90 (21 %} 358.53 120.40
September 132.11 (14 %} 296.31 40.02
October 86.03 (9 %} 348.61 7.87
November 28.59 (3 %} 153.88 0.00
December 0 0.00 0.00
Annual 79
Average Annual Runoff is approximately 260 inches.
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Penstock
~
Power house containing
turbine and g~nerato! ~
FigureS: Schematic of typical run of river small hydro electric project. A channel and forebay tank are not always included in
the project.
Run of river hydroelectric projects (figure 5) have a relatively small impact to the watershed and the
natural hydrologic patterns that occur throughout the year. little or no impoundment takes place, and
the natural river flows are utilized. Water is diverted upstream at an intake and routed through a
penstock and powerhouse before flowing back into the river. The river experiences a natural flow
regime both above and below the hydroelectric project. The reach of river that is between the intake
and return flows is referred to as the 'bypass' reach. This reach does experiences a reduction in flows.
Most run of river hydroelectric projects require that a minimum instream flow be maintained in the
bypass reach for aesthetic and biological (fish) concerns. The USGS often refers to normal river flows as
those that occur between 25 percent and 75 percent of the time in a river throughout the year. As a
preliminary estimate of instream flow requirements, a minimum of 40 cfs was assumed to be required
to be maintained in the bypass reach. This corresponds to a 25 percent exceedance during months that
significant stream flow occurs (May-November) or roughly equal to Yz of the mean annual flow for
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Whittier Creek. During the feasibility phase of a hydroelectric project, minimum instream flows are
refined and include monthly variations.
The flow duration curve (figure 6) was modified for Whittier Creek to include flows that would be
available for power production (natural flow less the minimum bypass reach flows).
900 ,-----~--~~~--T-~--~--~~----~._~~--~~--~~--~
BOO
700
600
~ 500
~
~ f!. 400
300
200
100
0 20 30 40 50 60 70 80 90 100
Percent EXCEEDANCE
Figure 6: Whittier Creek (extended record WY 2001-2010) flow duration (RED) with flows available for power production
. assuming a that the seasonal 25 percent exceedance value of 40 cfs must remain In the stream channel.
In addition to the average daily stream flow gage data available for Whittier Creek, annual peak flow
data was also available for Shakespeare Creek (15236200). Annual peak flow data for Shakespeare
Creek were used to calculate 1 percent chance of exceedance flow for this drainage. The 1 percent
chance of exceedance flow for the other three drainages was calculated using the USGS regional
regression equations for ungaged drainage basins (USGS 2003). The USGS ungaged regional regression
equations compared reasonably well with the station analysis for Shakespeare Creek. Similar flow
duration curves were estimated for all watersheds by scaling the Whittier Creek flows based on a ratio
of watershed areas.
Estimates of Power Production
A flow duration curve represents water available for power generation and was used for each watershed
to estimate the capacity of each hydropower plant and also to estimate the amount of power that can
be produced annually. The installed capacity for each site was selected as the 15 percent exceedance
value on the flow duration curve. This means that 85 percent of the time the power plant would be
operating at or below the rated capacity. Typical installed power production capacity for small
hydropower plants range from 10 percent to 30 percent on the exceedance duration curve. It was
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assumed that the plant would produce power through the full low end range of the flow duration curve
for purposes of calculating the average annual energy production. Based on the final turbine and
generator design, there will be a threshold below which no power is produced, typically 5 to 10 percent
of the turbines rated flow capacity. Preliminary turbines types were selected based on a standard
turbine selection chart from the European Small Hydropower Handbook. Penstock diameter was sized
using Manning's equation to produce a reasonable head loss of 5 to 10 percent and maintain velocities
at or below 10 feet per second. The final estimate of annual power production was calculated based on
the standard power equation using an overall system, or water to wire, efficiency of 55 percent. This
efficiency includes losses from the intake, penstock, turbine, generator, and transmission line. Typical
overall system efficiencies for small hydropower projects range from 50 percent to 60 percent.
Site Selection
Four potential sites were selected based on a review of previous studies, available USGS mapping, and a
site visit. The basic criteria for site selection included:
• Locations that were relatively close to existing roads, transmission line infrastructure, and the
city of Whittier
• Watersheds that are heavily glaciated
The locations and details of each watershed selected are given in figure 7 and table 2, respectively. The
mean annual flow for each watershed was estimated based on the ratio of watershed area to the
synthetic discharge record created for the lower Whittier Creek watershed. At least 2 to 3 years of data
should be collected at any site to be considered beyond the reconnaissance phase.
Table 2: Watersheds selected for screening
Area Glacier Watershed Watershed (sq. mi) Coverage(%) Aspect
Whittier Creek 4.19 57 North (Lower)
Whittier Creek 0.76 55 North (Upper)
Shakespeare 1.70 44 North Creek
1----------·-~--~-~----------
Learnard Creek 2.52 58 South
Cove Creek 1.1 29 North
'-----------------'--
1Based on USGS regional regression equations (USGS 2003)
2 Based on station peak flow gage record (36 years)
3 90-Percent Prediction Interval
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Mean Annual
Flow (cfs)
79
14
32
48
21
Average 100 year Basin Flow (cfs) Elevation 5%-95%3
(ft)
17701
2100 (911-3440)
430 1925 (217-852}
688 2
1775 (428-1640) -----r--~-------
11601
2675 (596-2270)
589 1
1499 (299-1160) -
---
" ~ ' ,. 1 .. ~ .. ft ' -• "' ... ..
0 3,7 50 7,500
_,.!
~---
.,..,.. __ -:"..,..'"~ ,, ~ ------·----~·~----·---·---
-·_/_l'w'Tl:C I
15,000
N
·~Ell> w ~
~ s
~~~~~-11111111-iiiiiiiiiiiiiiii~~~~~~ Feet
Figure 7: Hydropower Sites near Whittier evaluated in this interim reconnaissance report.
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Upper Whittier Creek
Whittier Creek is the glacial stream that created the alluvial fan that the city of Whittier sits upon. The
creek originates from the Whittier glacier in several branches that cascade down the steep watershed in
several distinct streams before converging. Whittier Creek is a step-pool stream that runs through a
canyon lined by steep rock walls. The creek exits the canyon at the apex of the Whittier Creek alluvial
fan where it runs down the west side of the alluvial fan and into Passage Canal. The community is
concerned about flooding from Whittier Creek. A locally built flood protection structure was constructed
on the right bank of the river through portions of the alluvial fan to help prevent flooding during high
flows. The National Resource Conservation Service (NRCS) recently completed a project to remove
boulders from a portion of Whittier Creek towards the apex of the alluvial fan.
A small hydro project intake would be located along an upper tributary of Whittier Creek at an elevation
of 525 feet (figure 8). This location is above a bedrock slot canyon that extends downstream to the top
of the Whittier Creek alluvial fan. The lower end of this slot canyon contains a large waterfall that is a
barrier to fish migration. No resident or anadromous fish are expected upstream of this first large set of
falls. This section of river appears to be stable with minimal sediment transport observed during the site
visit. The streambed was composed of cobble sized material with bedrock observed in a few areas near
the proposed intake location. Access to the intake would require a new road to be constructed along an
existing Forest Service trail. The cut and fill road would traverses steep terrain with occasional hillside
benches. It would require some rock excavation along the route. The access road and penstock would
generally be free of any avalanche hazard. The project intake may be within an avalanche hazard area
and would require further investigation. The powerhouse would be near the apex of the Whittier Creek
alluvial fan at an elevation of approximately 70 feet. A short tail race would discharge water back into
Whittier Creek downstream of the large falls identified as a fish migration barrier. In general, the
environmental effects of this project are thought to be minimal considering the small percentage of
water that would be diverted for hydropower generation and the fact that the bypass reach is a very
steep step pool stream with limited fish habitat. For planning purposes it was assumed that a portion of
stream flows should bypass the intake structure. Lateral inflows of approximately the same magnitude
as the Upper Whittier Creek occur just downstream from the proposed intake location. Utilizing all flows
within upper Whittier Creek for power generation may be an environmentally acceptable alternative
considering the type of stream and inflows immediately downstream from the intake. Site estimates are
explained in table 3.
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Figure 8: Topographic map of the proposed Upper Whittier Creek hydroelectric site.
Table 3: Upper Whittier Creek site estimates
Watershed Drainage Area (sq. mi.) 0.76
Insta lled Capacity (kW) 550
Est. Annual Energy (MWh) 1600
Est. Gross Head (ft.) 450
Est. Hydraulic Capacity (cfs) · 27
Number of turbine-generator units 1
Turbine Type Pelton
Est. Penstock I.D. (inches) 22
Est. Penstock Length (ft.) 2150
Est. power li~dis_!anceLmil~~1 .5
Photo: 1 Upper Whittier Creek Intake location looking upstream.
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17Jun11
N 80° 48.001' W 148° 40.680'
17Jun11
N 80° 45.998' W 148° 40.656'
Photo: 2 Upper Whittier Creek intake location looking downstream. A junction with similar sized stream occurs exists
approximately 300 feet downstream.
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17Jun11
N so• 45.997' w 148" 40.795'
Photo: 3 Upper end of the Whittier Creek canyon. Intake location is approximately 300 feet upstream.
Lower Whittier Creek
The Lower Whittier Creek option (figure 9) would also be on Whittier Creek. The intake structure would
be at the apex of the alluvial fan just after the creek exits a steep walled canyon at an approximate
elevation of 75 feet. Water would be routed through a penstock adjacent to Whittier Creek to a power
house at an elevation of approximately 25 feet, with water discharged back into Whittier Creek just
above the extreme high water elevation. Site estimates are shown in table 4. This project would require
only minimal access road improvements with good existing access to both the intake and powerhouse
sites. Whittier Creek was surveyed for adult fish migration barriers. This creek is listed in the ADF&G
anadromous catalog as habitat for Coho salmon (listed as "spawning"). The creek was accessed at the
end of the road past the campground and a migration barrier for Coho salmon was located just
upstream of the proposed intake location at the first large set of falls. No migration barriers for adult
Coho salmon were observed downstream ofthese falls. The project would need to be designed to
mitigate impacts to the anadromous fish population. A significant amount of sediment is transported
down Whittier Creek. The intake structure located at the head of the alluvial fan apex would require an
efficient method to flush sediment past the structure to maintain the channel's hydraulic capacity and
maintain an intake pool. Transported sediment in this reach ranges from fine grained glacial silt to large
diameter boulders. This alternative would impact several commercial properties adjacent to Whittier
Creek in this area.
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Figure 9: Topographic map of the proposed Lower Whittier Creek hydroelectric site.
Table 4: Lower Whittier Creek site estimates
Watershed Drainage Area (sq. mi.) 4.19
Installed Capacity (kW) 350
Est. Annual Energy (MWh) 1000
Est. Gross Head (ft.) so
Est. Hydraulic Capacity (cfs) 150
Number of turbine-generator units 1
Turbine Type Crossflow /Kaplan
Est. Penstock 1.0. (inches) 60
Est. Penstock Length (ft.) 1000
Est. power line distance (miles) .5
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17Jun11
N 60" 46.191' W 146° 41.319'
Photo: 4 Lower Whittier Creek intake location looking upstream.
17Jun11
N 60" 46.186' W 146• 41.307'
Photo: 5 Lower Whittier Creek intake location looking downstream
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Shakespeare Creek
Sheakespeare Creek drains a steep glaciated basin approximately 2 miles west of Whittier (figure 10).
Access to upper elevations of the creek is prohibited by steep unfavorable terrain and the threat of
avalanche activity, which extends into the power producing season (May-October). The project intake
would be located several hundred feet upstream from the mouth of the Shakespeare creek at an
elevation of approximately 200 feet. Site estimates are shown in table 5. The reach appears to be stable
with a cobble bed through the lower reaches. Access would require construction of new road extended
along the east side of the creek from the end of the existing bunker road. The penstock would be routed
downstream adjacent to the creek to a power house located at an elevation of approximately 50 feet.
Water would be discharged through a tail race back into Shakespeare creek above the Whittier access
road. The bypass reach is listed in the ADF&G anadromous catalog as habitat for pink salmon (listed as
"present") and Coho salmon (listed as "spawning"). Shakespeare Creek was surveyed for adult fish
migration barriers. No migration barriers along the bypass reach were observed for adult pink salmon,
which have the weakest jumping ability among salmon that might be found in the creek. Adult pink
salmon can leap as high as ~3.5 feet vertically A project on Shakespeare creek would need to be
designed to mitigate impacts to the anadromous fish population.
Figure 10: Topo map of the proposed Shakespeare Creek hydroelectric site.
Table 5: Shakespeare Creek site estimates
Watershed Drainage Area (sq. mi.) 1.7
Installed Capacity (kW) 400
Est. Annual Energy (MWh) 1200
Est. Gross Head (ft.) 150
Est. Hydraulic Capacity (cfs) 60
Number of turbine-generator unit~ 1
15
Turbine Type Francis
Est. Penstock I.D . (inches) 44
Est. Penstock length (ft.) 3000
Est. power line distance (miles) . .5
-
17Jun11
N so• 46.232' w 146" 44.231'
Photo: 6 Shakespeare Creek intake location looking upstream.
Learnard Creek
learnard Creek drains a steep glaciated basin approximately 2 miles Northwest of Whittier (figure 11).
Access to upper elevations of the creek is prohibited by steep unfavorable terrain and the threat of
avalanche activity, which extends into the power production season (May-October). Access to the
creek is straight forward with an existing road to the shooting range located adjacent to the lower
portion of the creek. The project intake would be located at an elevation of approximately 150 feet.
The intake would require evaluation of the avalanche and rock fall hazard. Mitigation may be required
for either hazard or relocation of the intake downstream outside of the identified hazard area. The
penstock would be routed downstream to a power house at an approximate elevation or 25 feet. Site
estimates are shown in table 6. learnard Creek was not surveyed for fish migration barriers due to a
road closure for construction. This creek is not listed in the ADF&G anadromous catalog, although this
only means that the presence of anadromous fish has not been documented, not that absence has been
confirmed. Based on contour intervals on maps and photos take by others, it appears that Coho salmon
could access the creek up through the location of the intake.
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Figure 11: Topo map of the proposed Learnard Creek hydroelectric site.
Table 6: Shakespeare Creek site estimates
Watershed Drainage Area (sq. mi.) 2.5
Installed Capacity (kW) 600
Est. Annual Energy (MWh) 1800
Est. Gross Head (ft.) 125
Est. Hydraulic Capacity (cfs) 90
Number of turbine-generator units 1
Turbine Type Francis
Est. Penstock I.D. (inches) 48
Est. Penstock Length (ft.) 2000
Est. power line distance (miles) 1
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17Jun11
N so· 47.015' w 148. 43.763'
Photo: 7 Learnard Creek intake location looking upstream.
17Jun11
N 60" 47.012' W 148• 43.764'
Photo: 8 Learnard Creek intake location looking downstream.
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Cove Creek
Cove Creek drains a steep watershed to the east of Whittier (figure 12). The creek descends down
through a residential subdivision located along Shotgun Cove Road . An existing concrete dam exists on
the creek. This dam is approximately 15 feet high and was constructed in the 1940's to support the
military installation in Whittier. Portions of this dam and the small pool that is formed upstream could
possibly be utilized for a small hydropower intake on Cove Creek. The access road, though short, would
be through difficult terrain and likely impact adjacent residential property owners. It would require cut
and fill sections through bedrock. A power house could be located on the downstream side of Shotgun
road with the tail race discharging into Cove Creek. Site estimates are shown in table 7. Lower Cove
Creek is a recreational area with a large parking lot and foot path leading to the intertidal area of Cove
Creek. The lower section of Cove Creek is listed in the ADF&G anadromous catalog as habitat for pink
salmon (listed as "present") and Coho salmon {listed as "present and "spawning"). A series of waterfalls
within the bypass reach of Cove Creek are likely fish migration barriers.
Figure 12 Topographic map of the proposed Cove Creek hydroelectric site.
Table 7: Cove Creek site estimates
Watershed Drainage Area (sq. mi.) 1.1
Installed Capacity (kW) 140
Est. Annual Energy {MWh) 400
Est. Gross Head (ft.) 75
Est. Hydraulic Capacity {cfs) 40
Number of turbine-generator units 1
Turbine Type Kaplan
Est. Penstock I.D. {inches) 28
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Est. Penstock Length (ft.) 700
Est. power line distance (miles) 1
17Jun11
N &o· 46.549' w 148" 39.750'
Photo: 9 Existing dam on Cove Creek.
17Jun11
N &o• 46.545' w 146" 3t.75r
Photo: 10 Pool above the existing dam on Cove Creek.
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ROM Cost Estimates and Issues Identified
Total project costs were estimated (2011 dollars) based on separate costs for the intake, penstock,
powerhouse (including generating equipment), access road and transmission lines. The costs are
considered rough order of magnitude costs with an estimated error of plus 50% or minus 10%. The
accessibility of the site is taken into account in the overall access road costs. The penstock costs reflect
the length, diameter and terrain of the penstock and the powerhouse costs reflect the size of generating
equipment. Percentages were applied to the estimated construction costs for planning design and
engineering services needed prior to construction and summed with the construction costs to estimate
a total project cost. The per KwH cost is calculated assuming a 4% interest 30 year loan is used to finance
the project with annual operations and maintenance cost estimated at 3% of the overall construction
cost. Whittier is a grid connected community; in order to be cost effective the cost per kilowatt hour for
a small hydropower project should be less than the cost of commercially available power.
Table 8: ROM Cost Estimates for Sites Evaluated.
Watershed Total Project Cost Cost per Kilowatt Cost per Kilowatt Recommended for (Includes Planning Design of Installed hour Further Study and Engineering) Capacity
Whittier Creek $2,700,000 $8,700 $0.26 No (Lower)
Whittier Creek $3,800,000 $6,000 $0.18 No (Upper)
Shakespeare Creek $4,300,000 $10,100 $0.30 No
Learnard Creek $4,300,000 $8,300 $0.25 No
Cove Creek $1,800,000 $11,500 $0.35 No
--
Several significant issues were identified for each site that are listed in the table below:
Table 9: Significant Issues Identified.
All Sites • Low plant capacity factors for all sites based on measured flows at Whittier
Creek.
• Dependable power only available during the summer months .
• Inexpensive line power available .
Whittier Creek • High sediment discharge and transport of cobbles and boulders through intake
(Lower) area.
• ROW required through downstream businesses for penstock and powerhouse .
• Anadromous Fish Habitat
Whittier Creek • Access road would require recreational trail relocation .
(Upper) • Possible avalanche hazard near intake .
• Stream gage required to confirm flows on the smaller upper watershed .
Shakespeare Creek • Anadromous Fish Habitat
• Stream gage required to confirm flows .
Learnard Creek • High sediment content and transport of cobbles and boulders through intake
area.
• Avalanche and landslide concerns near intake .
• Anadromous Fish Habitat
• Stream gage required to confirm flows .
Cove Creek • Located adjacent to residential property .
• Low annual power production
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• Stream gage required to confirm flows.
• Lower Cove Creek is a popular recreational area.
Conclusions and Recommendations
Five potential small hydropower sites were investigated near the city of Whittier, with an initial
reconnaissance level of screening to determine if a project warrants further feasibility level
investigation. The lowest cost per kilowatt hour was Upper Whittier Creek, which is the site with the
highest available hydraulic head. High head sites tend to be more economical to develop. Small
hydropower energy production for the city of Whittier has the following unique challenges to becoming
a viable economic alternative for electrical energy:
• Sufficient stream flows available for power generation occur less than 50 percent of the year.
• Line power is available at reasonable costs from much larger and more efficient hydropower and
natural gas fired power plants.
• Access to upper portions of the glaciated watersheds is difficult due to steep rocky terrain.
No sites evaluated in this reconnaissance study are recommended for further evaluation based on the
estimate cost per kilowatt hour for energy production. Upper Whittier creek was found to be the most
cost effective project. If overall construction costs could be reduced by combining the project with a
recreational access road, the project may become a viable alternative for energy. However, this site will
be limited to power production during summer months only.
22
"!
T
j
I
' Ji
J
J
I
1
l
1
Appendix A: Comparison of Whittier Creek to Twentymile River flows
9,ooo.------------------------------------------------------------------,
8,000
7 ,000
~ 6,000
~ 5,000
3:
ft. 4,000
3,000
2,000
1,000
or "'"---"'~~--...... ~ l
400
350
300
~ 250
~ 200
3: 150 0 u:: 100
50
0
Nov Jan
2009 I
---Twenty mile River (15272380)
Mar May Jul
2010
---WMtier Creek (15236210)
Sep Nov
aoo.-------------------------------------------------------------------,
500
400
~ 300
3:
..2
LL
200
100
0 r .........._ '\4-ll 1 ', a, ,....,-...,_ ~ l I -I j -• .. ,
Nov 1
I Jan Mar
2009 I
---Whittier Creek (15236210)
May Jul
2010
---Whittier Creek (Synthetic)
23
Sep Nov