HomeMy WebLinkAboutTriangle Lake Hydroelectric Project Feasibility Study - Sep 2017 - REF Grant 7040074Feasibility Study
Triangle Lake Hydroelectric Project
September 2017
Feasibility Study
Triangle Lake Hydroelectric Project
September 2017 |i
Contents
1 Executive Summary ............................................................................................................................1
2 Introduction..........................................................................................................................................2
3 Background Information......................................................................................................................3
3.1 Previous Studies .......................................................................................................................3
3.2 Site Visits...................................................................................................................................3
4 Hydrology ............................................................................................................................................4
4.1 Existing United States Geological Survey Data........................................................................4
4.2 Basin Discharge Analysis..........................................................................................................4
4.3 Flow Duration ............................................................................................................................6
4.4 Gaged Data...............................................................................................................................8
4.5 Summary.................................................................................................................................10
5 Project Considerations......................................................................................................................11
5.1 Penstock Routing ....................................................................................................................11
5.2 Usable Storage........................................................................................................................11
5.3 Access/Transmission Line Routing.........................................................................................11
6 Project Arrangement .........................................................................................................................12
7 Energy Generation ............................................................................................................................13
7.1 Assumptions............................................................................................................................13
7.2 Results.....................................................................................................................................13
7.3 Sensitivity ................................................................................................................................13
8 Cost Estimates ..................................................................................................................................14
8.1 Indirect Construction Costs.....................................................................................................14
8.2 Contingencies..........................................................................................................................14
8.3 Interest During Construction....................................................................................................14
8.4 Results.....................................................................................................................................14
9 Economics.........................................................................................................................................15
9.1 Financing Costs.......................................................................................................................15
9.2 Operations and Maintenance..................................................................................................15
9.3 Grant Funds ............................................................................................................................15
9.4 Results.....................................................................................................................................15
9.5 Ancillary Benefits.....................................................................................................................16
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Tables
Table 4.1 – Basin Characteristics Comparison.............................................................................................4
Table 4.2 – Triangle Lake Surrogate Streamflow Frequency.......................................................................7
Table 4.3 – Triangle Lake Flow Frequency Comparison..............................................................................9
Table 6.1 – Triangle Lake Project Parameters ...........................................................................................12
Table 7.1 – Energy Summary .....................................................................................................................13
Table 8.1 – Cost Estimate Summary..........................................................................................................14
Table 9.1 – Energy Cost Summary.............................................................................................................15
Figures
Figure 2.1 – Vicinity Map...............................................................................................................................2
Figure 4.1 – Triangle Lakeaverage monthly discharge based on surrogate data from Purple Lake,
WY 1947-1956. ................................................................................................................................5
Figure 4.2 – Triangle Lake average monthly discharge scaled from Fish Creek, WY 1947-1956...............6
Figure 4.3 – Triangle Lake average monthly discharge scaled from Fish Creek, WY 1917-2016...............6
Figure 4.4 – Triangle Lake average monthly discharge, WY 2014-2015. ....................................................8
Figure 4.5 – Fish Creek average monthly discharge scaled, WY 2014-2015. .............................................8
Figure 4.6 – Triangle Lake mean daily flow frequency. ..............................................................................10
Appendices
Appendix A – Geotechnical Reconnaissance Report
Appendix B – Flow Duration Comparisons
Appendix C – Drawings
Appendix D – Energy Simulation
Appendix E – Cost Estimate
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Triangle Lake Hydroelectric Project
September 2017 |1
1 Executive Summary
Metlakatla Power & Light (MP&L) retained HDR Alaska, Inc. (HDR) to assess the
feasibility of a small hydroelectric project using water from Triangle Lake. The Triangle
Lake hydroelectric project would use 120 cubic feet per second (cfs) at a net head of 309
feet resulting in an installed capacity of 2.75 megawatts (MW).
The project’s estimated construction cost is $29.6 million with an annual average
generation of 11,555 MW hours operating in a run-of-river mode. Additional operational
benefits and energy could be obtained if the lake level was allowed to fluctuate slightly.
An additional project advantage would include a reduction in the strain on the
communities’ existing water supply system by offsetting generation from Chester Lake.
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2 Introduction
HDR provided MP&L with a feasibility assessment for a potential small hydroelectric
project on Triangle Lake near Metlakatla, AK (Figure 2.1).
The work performed quantifies the amount of energy and the cost of energy that could be
used on Annette Island or transmitted on a Metlakatla-Ketchikan electrical intertie. Work
scope included:
Review of available project documentation and related information
Field visit to the sites by team members
A geotechnical reconnaissance investigation.
Development of a conceptual project layout
Review of existing hydraulic and hydrologic parameters
Estimation of energy production and new facility costs
Preparation of this summary report
Figure 2.1 – Vicinity Map
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3 Background Information
3.1 Previous Studies
A hydroelectric project at Triangle Lake has been investigated at a reconnaissance level
several times in the past originating with the Chester Lake Project Feasibility Report,
May 1982,prepared by Harza Engineering Company.
More recent work includes:
Review of Chester and Triangle Lake Hydro Projects, July 2011,prepared by EES
Consulting and Electric Power Systems, Inc.
Hydropower Site Evaluation & Planning Services Project,December 2013, prepared
for McMillen, LLC, and Southeast Alaska Power Agency (SEAPA) by Tetra Tech.
Annette Island Hydropower Evaluation Completion Report: Resource Development
and Market Opportunities, June 2014, prepared by McMillen, LLC.
3.2 Site Visits
In May 2016, two senior engineers from HDR and an engineering geologist from Golder
Associates performed a reconnaissance of the proposed site. The site visit consisted of a
review of the site, site access, and transmission line routes utilizing both a helicopter and
ground-based investigations. The geotechnical reconnaissance review is included in
Appendix A.
A ground surveying scope of work was developed based on the initial site visit. A
Ketchikan-based land surveyor performed field work during the summer of 2016 to
establish elevations, develop contour mapping, and identify the locations of proposed
project features.
In October 2016, two senior engineers from HDR reviewed the survey and project layout
information in the field.
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4 Hydrology
The Triangle Lake drainage basin is located on Annette Island in Southeast Alaska, and
is approximately 5.5 square miles at the lake’s outlet. It was delineated using a
geographic information system (GIS). Basin characteristics were determined from
publicly available information, including annual precipitation, mean elevation, and land
cover. Much of the basin is composed of relatively broad valley floors between hills
ranging in elevation up to 2,200 feet. The basin includes Triangle Lake, which totals 13
percent of the basin area (USGS National Hydrography Dataset 2016), is composed of
forest and scrub (USGS National Land Cover Database 2016), and contains no glaciers
(GLIMS Randolph Glacier Inventory 2016). The basin drains into Triangle Lake, which
has a natural outlet on the lake’s north side.
4.1 Existing United States Geological Survey Data
No United States Geological Survey (USGS) stream gage data exists for the Triangle
Lake basin. However, the USGS operated a continuous stream gage (15058000) at the
Purple Lake outlet from July 1947 through September 1956 and at Fish Creek
(15072000) near Ketchikan from June 1915 to present.
The Purple Lake basin is approximately 6.6 square miles, and is located on Annette
Island, which is six miles south of the Triangle Lake basin. The Fish Creek basin is
approximately 34.6 square miles, and is located near Ketchikan. It is 25 miles north-
northeast of the Triangle Lake basin. Table 4.1 displays basin characteristics for these
three sites.
Table 4.1 – Basin Characteristics Comparison
Characteristic Purple Lake Basin
(15058000)
Period of Record:
1947-1956
Triangle Lake
Basin
Fish Creek Basin
(15072000)
Period of Record:
1915-2017
Average Annual
Precipitation (1971-2000
PRISM Dataset)
117 inches 126 inches 166 inches
Basin Area (GIS-delineated)6.6 square miles 5.5 square miles 34.6 square miles
Mean Basin Elevation
(ASTER GDEM)
920 feet 991 feet 1280 feet
Percent Lake Area (NHD)20%13%10%
All recorded daily discharge data for USGS gaged sites was downloaded in January
2017.
4.2 Basin Discharge Analysis
The strong similarity and geographic proximity between the Purple Lake and Triangle
Lake basins provides a good frame of reference for estimating flows from Triangle Lake
using USGS gaged flows from Purple Lake as surrogate data. The basin ratio was
calculated by dividing the basin area of Triangle Lake by the basin area of Purple Lake
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Triangle Lake Hydroelectric Project
September 2017 |5
resulting in a ratio of 83.3 percent. The basin ratio was multiplied by the daily gaged
flows for the period of record from Purple Lake to obtain estimated flows for the Triangle
Lake basin.
The Fish Creek basin also has similar basin characteristics to the Triangle Lake basin.
The flow data from Fish Creek was scaled via basin size ratio to allow comparison to the
scaled Purple Lake flow data. The Fish Creek to Triangle Lake basin ratio is 15.9
percent. Because of the significant difference in basin size, the Fish Creek data was
used only for comparison, and not as surrogate data for the Triangle Lake basin flows.
The estimated average annual surrogate flow for Triangle Lake during WY 1947 to WY
1955 was 75 cfs. The estimated average monthly discharge is shown in Figure 4.1.
Figure 4.1 – Triangle Lake average monthly discharge
based on surrogate data from Purple Lake, WY 1947-1956.
The Fish Creek basin’s average monthly flows, scaled to Triangle Lake by basin size, are
displayed in Figure 4.2 and Figure 4.3. A comparison of WY 1947-1956 to the period of
record (POR) WY 1917-2016 indicates a slightly higher discharge during the period from
1946 to 1956 during the months of October, May, June, July, and September. On
average, the winter months have a lower discharge than the POR. This combination may
be explained by a higher snowfall and larger snowpack during the period when the
Purple Lake streamflow data was collected, which coincided with a negative (cool) phase
of the Pacific Decadal Oscillation (Mantua, 2017). In Southeast Alaska, negative phases
of the Pacific Decadal Oscillation generally result in more snow during the winter, which
in turn leads to lower winter streamflow but higher spring and early summer streamflow
during snowmelt (Neal and others 2002).
130
103
91
63
74
52
77 77
60
37
51
79
0
20
40
60
80
100
120
140
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Triangle Lake Scaled from Purple Lake - WY 1947-1956
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Figure 4.2 – Triangle Lake average monthly discharge scaled
from Fish Creek, WY 1947-1956.
Figure 4.3 – Triangle Lake average monthly discharge scaled
from Fish Creek, WY 1917-2016.
4.3 Flow Duration
To determine flow duration characteristics, the mean daily discharge data was sorted
and ranked. Then the time that a given flow was equaled or exceeded was computed by
dividing the rank by the total number of observations plus one and expressed in
percentages. This method was used for the Triangle Lake surrogate streamflow scaled
from Purple Lake, the Triangle Lake surrogate streamflow scaled from Fish Creek, and
118
79
57
31
41
29
56
101 96
62 56
83
0
20
40
60
80
100
120
140
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepAverage Monthly Discharge, cfsTriangle Lake scaled from Fish Creek - WY 1947-1956
110
89
67 59 51
42
57
79 73
53 53
74
0
20
40
60
80
100
120
140
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepAverage Monthly Discharge, cfsTriangle Lake scaled from Fish Creek - POR 1916-2017
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Triangle Lake Hydroelectric Project
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the discharge data measured at the outlet of Triangle Lake during calendar year 2015. A
flow frequency table from the surrogate flow data for Triangle Lake scaled from Purple
Lake is presented in Table 4.2.
Average monthly flow frequency is presented for October through September, and is also
presented as annual exceedance values. Flow data scaled by the basin ratio for Fish
Creek is also presented as the POR and for the overlapping time the Purple Lake gage
was operating between 1947 and 1956. Additional flow duration comparisons are
included in Appendix B.
Table 4.2 – Triangle Lake Surrogate Streamflow Frequency
Percent Exceedance
Month 1%2%5%10%20%30%50%70%80%90%95%98%99%
October 333 314 271 244 196 159 111 77 58 42 32 27 25
November 260 258 231 207 162 123 87 63 53 36 24 14 13
December 362 320 213 163 124 108 76 53 42 26 19 11 8
January 207 199 163 128 98 78 58 33 19 6 3 2 2
February 417 417 183 135 97 76 56 36 25 16 14 13 11
March 208 155 128 98 67 54 43 32 28 23 18 17 17
April 321 276 193 143 89 83 63 46 38 28 19 15 14
May 245 217 177 130 103 83 63 53 46 38 33 29 27
June 248 236 156 113 79 60 47 35 28 20 15 12 11
July 178 131 92 73 55 44 28 19 14 10 8 7 6
August 234 227 181 128 88 60 27 14 11 6 4 3 2
September 291 263 205 169 125 98 57 37 28 18 9 5 4
Annual 304 251 201 153 108 83 55 36 27 16 10 6 4
POR Annual Scaled Fish Creek Discharge (15072000)
Annual 300 250 181 138 98 77 51 32 24 16 12 9 7
1947-1956 Annual Scaled Fish Creek Discharge (15072000)
Annual 302 248 183 141 103 81 52 29 19 12 10 7 6
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4.4 Gaged Data
MP&L collected stage data between September 2013 and December 2015 (WY 2014-
2015). Instantaneous discharge measurements were used to create a rating curve that
was used to convert stage data into discharge data for the recording period. The rating
curve was broken into multiple segments, and many of the data points were not used.
The average monthly flows for available data are shown in Figure 4.4.
Figure 4.4 – Triangle Lake average monthly discharge, WY
2014-2015.
Triangle Lake average monthly flows scaled from the Fish Creek streamflow during the
same time period are shown in Figure 4.5.
Figure 4.5 – Fish Creek average monthly discharge scaled, WY
2014-2015.
74
63 69
81
43
56
80
27 22
33
42
65
0
20
40
60
80
100
120
140
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepAverage Monthly Flows, cfsTriangle Lake - WY 2014-2015
114
66
90
110
38
66
84
64
34
44
68
87
0
20
40
60
80
100
120
140
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepAverage Monthly Flows, cfsFish Creek Scaled - WY 2014-2015
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The January and April peak monthly discharges may indicate that 2014-2015 was slightly
warmer than during the 1916-2017 POR for Fish Creek with precipitation falling as rain
during January. Typical high flow for Southeast Alaska occurs during May and June as
snow melts, though June had the lowest average monthly flow recorded. The Pacific
Decadal Oscillation was in a positive (warm) phase during 2014-2015.
Flow frequencies were compared between the gaged data, the Triangle Lake annual
average surrogate data scaled from Purple Lake, and the Triangle Lake annual surrogate
data scaled from Fish Creek. Table 4.3 illustrates the comparison.
Table 4.3 – Triangle Lake Flow Frequency Comparison
Percent Exceedance
Data 1%2%5%10%20%30%50%70%80%90%95%98%99%
2013-2015 Gaged
Discharge at Triangle
Lake Outlet
193 162 139 122 95 78 45 23 14 7 5 3 3
1947-1956 Triangle
Lake Annual
Discharge
scaled from
Purple Lake
304 251 201 153 108 83 55 36 27 16 10 6 4
2013-2015 Triangle
Lake Annual
Discharge
scaled from
Purple Lake
305 259 188 148 110 85 56 37 29 19 13 9 6
1916-2017 Triangle
Lake Annual
Discharge
scaled from Fish
Creek
300 250 181 138 98 77 51 32 24 16 12 9 7
The reasonable correlation on an annual basis for all years indicates that peak and low
flows tend to average out over a long term as indicated by the 100 years Fish Creek’s
gaged data.
Triangle Lake’s gaged discharge flow frequency was plotted alongside the flow
frequency for the basin’s surrogate data, and is displayed in Figure 4.6. The graph shows
good correlation of flow frequencies between 20 and 100 percent. The deviation between
the USGS data and locally collected flow data at high flow may be due to the short
duration of data collection or challenges with computing high flow streamflows with
limited data.
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Figure 4.6 – Triangle Lake mean daily flow frequency.
4.5 Summary
The Triangle Lake drainage basin has similar basin characteristics and is located a short
distance from the Purple Lake drainage basin, which was gaged by the USGS from 1947
to 1956. The Purple Lake gage record shows the annual flow duration curve for the 10-
year period is nearly identical to the Fish Creek gage’s annual flow duration curve of
scaled streamflow for the past 100 years based. The Purple Lake data provides an
excellent surrogate hydrologic record for Triangle Lake when analyzing annual flows.
The average monthly flow variation identified in the Fish Creek basin indicates that WY
1947-1956 may have been wetter or experienced more precipitation as snow during the
winter than the average year between WY 1917-2016.
The limited flow data collected at the outlet of Triangle Lake corresponds well with the
scaled Purple Lake surrogate data between the 20 and 100 percent annual flow
frequencies. The general pattern during the WY 2014-2015 is similar between gaged
flow data at Triangle Lake and scaled flow data for Fish Creek with high flows during
October, January, April, and September and lower than average flows during June.
0
100
200
300
400
500
600
0% 20% 40% 60% 80% 100%Discharge (cfs)Daily Exceedance Probability
Surrogate
Data
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5 Project Considerations
The following issues were taken into consideration in developing the project
arrangement.
5.1 Penstock Routing
Triangle Lake is surrounded almost entirely by mountains. There are only two possible
routes to convey water from Triangle Lake to a powerhouse located near tidewater. The
first is the natural outlet from the lake, and the second is through a saddle approximately
0.5 miles east of the lake outlet. Based upon field investigations, it was concluded that it
would not be economically feasible to route the penstock through the steep canyon
section of the creek immediately below the lake. The remaining alternative of routing
through the saddle will require a significant rock cut.
5.2 Usable Storage
Triangle Lake has a surface area of approximately 450 acres at an outlet control
elevation of 359.0 feet. Usable storage could be created by either constructing a dam to
raise the pool elevation or by drawing the existing lake level down with a submerged
intake. Construction of a dam was considered to not be a viable option due to the lack of
a desirable site, difficult access considerations, and high costs associated with dam
construction. Drawdown of the lake would be possible with a deep or siphon intake;
however, lowering the lake’s water levels means the cut through the saddle would need
to be deeper. Additionally, lake water levels below the natural outlet level would make
the release of environmental flows into the existing stream channel difficult. As such, it
was concluded the project would not attempt to utilize active storage.
5.3 Access/Transmission Line Routing
The construction and maintenance cost for remote projects in Alaska is greatly
influenced by the amount of and quality of access. Previous studies were based upon
marine access, man camps, and helicopter construction of transmission lines. Based
upon our experience, construction costs can be greatly minimized if road access to all
project features is available. Our project arrangement focuses on providing road access
to connect to the existing road system at the ferry terminal. This will provide for direct
access to the goods and services available in Metlakatla and Ketchikan. Additionally an
access road will allow the transmission line to be constructed and maintained using
conventional methods, and it will greatly facilitate routine operations and maintenance
throughout the life of the project.
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6 Project Arrangement
The following are the proposed project features:
1. A concrete intake structure located approximately 0.5 miles east of the existing lake
outlet. The intake will be equipped with trash racks, a bell-mouthed penstock
entrance, and shut-off valve.
2. A 54-inch-diameter steel penstock (approximately 5,800 feet long) will convey water
from the intake structure to the powerhouse located near tidewater. The initial 400
feet of the pipeline would have a mild slope, and be located in a deep cut in the
hillside. This section of penstock will be buried for protection and to allow access to
the intake. The remaining 5,400 feet of penstock will be above ground on saddle
supports spaced at approximately 50 feet. Concrete thrust blocks will be provided at
significant changes in alignment.
3. A powerhouse that is approximately 60 feet by 60 feet and 25 feet high, and that will
be located near tidewater. It will be a pre-engineered metal building with a reinforced
concrete foundation. A bridge crane will be provided to aid in equipment installation
and maintenance.
4. A vertical five-jet Pelton turbine and synchronous generator with a rated capacity of
2,750 kilowatts. A Pelton turbine was selected to provide high efficiency generation
across a wide range of flows and to reduce penstock-related costs.
5. A small switchyard located adjacent to the powerhouse.
6. A 34.5 kilovolt transmission line that will be approximately 6.5 miles to transmit the
power from the switchyard to an interconnection near the ferry terminal.
7. An access road that will be approximately 6.5 miles to connect the project site to the
existing road system at the ferry terminal. Bridge crossings will be required across
the outlets of Lower Todd Lake and Triangle Lake.
The key project parameters are shown in Table 6.1.
Table 6.1 – Triangle Lake Project Parameters
Headwater, ft 359
Turbine Centerline, ft 33
Net Head, ft 309
Design Flow, cfs 120
Capacity, kW 2,750
Project layout drawings are presented in Appendix C.
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7 Energy Generation
The project’s energy generation was estimated using HDR’s proprietary software
Hydroelectric Evaluation Program (HEP). HEP has been specifically designed to model
run-of-river operations. It uses tabulated daily flows, turbine and generator efficiencies,
friction coefficients, and physical parameters to simulate energy production through a
period of record. Turbine and generator efficiencies are determined from tables based
upon equipment manufacturer’s data. Output from HEP consists of the unit(s) effective
capacity rating, simulated production in megawatt hours (MWh), percent operating time,
and overall plant factor.
7.1 Assumptions
The following are the key assumptions used in modeling energy production: An
environmental flow release of 5 cfs per month, and losses totaling 4 percent were
included for station service, transformer and transmission losses, and scheduled
downtime.
7.2 Results
Using the assumptions and the project configurations described above, the project’s
average annual energy generation is shown in Table 7.1, and in detail in Appendix D.
Table 7.1 – Energy Summary
Avg. Annual Energy, MWh 11,555
Capacity, kW 2,750
Plant factor 48%
Days shutdown due to low
water
14
7.3 Sensitivity
The above analysis was based strictly upon a run-of-river operation, which is dictated by
the need to provide environmental flow releases into the bypassed reach of the diverted
stream. However, the outlet to Triangle Lake is a non-anadromous stream, and there is
little if any use by native species (Tetra Tech, 2013). If the environmental flow release
was reduced to zero, average annual generation would increase by approximately 500
MWh.
More importantly, if an environmental flow was not required Triangle Lake could be
slightly regulated to provide operational flexibility on the interconnected system, and to
capture high flow events that would normally cause spills. For example, 2 feet of active
storage would be sufficient to capture a vast majority of high flow events that would
normally spill or to provide four days of continuous peak capacity with no inflow.
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14 | September 2017
8 Cost Estimates
An opinion of probable construction costs was derived for the project presented above.
Base work units and unit prices were developed and applied consistently to the various
project features. For the generating equipment and penstock materials, budgetary
quotations were requested from manufacturers.
8.1 Indirect Construction Costs
Indirect construction costs associated with engineering, managing construction,
licensing, permitting, and the Owner’s internal costs were added to the direct
construction cost estimate as either percentages or lump sum amounts. However, due to
the legal status that exists on Annette Island, it is unclear how much licensing and
permitting would actually be required.
8.2 Contingencies
A contingency of 30 percent was added to the direct and indirect construction costs totals
to reflect the layout and design uncertainty that won’t be resolved until later in the
development process.
8.3 Interest During Construction
An assumed financial cost representing the interest accrued at a 5 percent annual
percentage rate during a 24-month construction period was also included.
8.4 Results
A detailed cost estimate is presented in Appendix E. The results are shown in Table 8.1.
Table 8.1 – Cost Estimate Summary
Item Dollar Amount
Direct Construction Costs 18,970,000
Contingency 5,700,000
Engineering
Licensing & Permitting
1,900,000
250,000
Owners Administration 450,000
Construction Management 900,000
Interest During Construction 1,400,000
Total Project Costs 29,650,000
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Triangle Lake Hydroelectric Project
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9 Economics
This scope of work did not include a detailed economic evaluation. However, to get a
conceptual view of the project’s economics we made some generic financial
assumptions. The results are presented as the first year estimated annual costs per
kilowatt hour in 2017 dollars. The assumptions and results are presented below.
9.1 Financing Costs
Annual financing costs were determined assuming 100 percent debt and a constant
principal and interest payment calculated over 30 years at a 5 percent annual percentage
rate. All project costs have been assumed to be capitalized and financed.
9.2 Operations and Maintenance
First year operations and maintenance (O&M) expenses were assumed to include labor,
direct and indirect expenses, and insurance. It was assumed that the project would be
designed for unmanned operations, and would be part of a larger organization meaning
the project would experience lower administrative expenses. On-site O&M labor would
be limited to periodic inspections and seasonal maintenance. Total labor, expenses, and
owner’s general and administrative expenses were estimated at $50,000 per year. A
repair and replacement fund of $15,000 was also included. General liability and business
interruption insurance was estimated at $1.00 per $100.00 of asset.
9.3 Grant Funds
Almost all hydroelectric projects in Alaska are constructed with some level of grant
funding. The amount of potential grant funding possible for this project is unknown at this
time. As such, we have analyzed the effect of grant funding in $5 million increments to
show their effect on overall project economics.
9.4 Results
Assuming a $29.65 million project development cost, $365,000 annual operating
expenses, and 11,555 kilowatt hours of annual generation, the average first year cost of
energy for the project is shown in Table 9.1.
Table 9.1 – Energy Cost Summary
Grant Funding Average First Yr Energy Cost, kWh
0 $0.20
$5M $0.17
$10M $0.14
$15M $0.12
$20M $0.09
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9.5 Ancillary Benefits
The system load on Annette Island is in approximately 15,000-18,000 MWh annually.
MP&L uses its hydropower resources to meet this load as much as is possible. One of
these resources, Chester Lake, is also the community’s source of drinking water. During
dry years like those that have recently occurred, hydro generation from Chester Lake has
to be curtailed to maintain adequate lake levels for water supply. The community is
currently looking at other options for providing additional water sources. The addition of
Triangle Lake to the system would have the ancillary benefit of allowing more drinking
water to be stored in Chester Lake, and would likely offset the need and cost of
developing new drinking water sources.
RE: GEOTECHNICAL RECONNAISSANCE, TRIANGLE LAKE HYDROELECTRIC PROJECT
1.0 INTRODUCTION
2.0 METHODOLOGY
3.0 GENERAL SITE CONDITIONS
3.1 Proposed Intake and Through-Cut
Golder Associates Inc.
Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South AmericaGolder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South AmericaGolder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America
3.2 Penstock
3.3 Powerhouse
3.4 Road and Transmission Line
4.0 CONCLUSIONS AND RECOMMENDATIONS
4.1 Proposed Intake and Through-Cut
4.2 Penstock
4.3 Powerhouse
4.4 Transmission Line and Access Road
5.0 GEOLOGIC HAZARDS
6.0 USE OF REPORT
7.0 CLOSING
GOLDER ASSOCIATES INC.
Draft, No Signatures
8.0 REFERENCES
FIGURES
VICINITY MAP
REFERENCE
APPENDIX A
REPRESENTATIVE FIELD PHOTOGRAPHS
Project Title:Triangle Lake Hydroelectric Project
PHOTO 1
PHOTO 2
Project Title:Triangle Lake Hydroelectric Project
PHOTO 3
PHOTO 4
Project Title:Triangle Lake Hydroelectric Project
PHOTO 5
PHOTO 6
PHOTO 7
Gilbert Gilkes & Gordon Ltd
Canal Head North, Kendal, Cumbria
LA9 7BZ, England
North American contact details;
Darren Wager - d.wager@gilkes.com
Telephone: +1 604-603-7139
GILKES BUDGET OFFER FOR THE SUPPLY OF HYDRO ELECTRIC EQUIPMENT
Client: HDR Paul Berkshire
Project Name: Annette Island Hydroelectric Project
Gilkes Reference No: DW-PB-Annette-Jun16-2017
Date: Friday, 16 June 2017
HDR
2525 C Street, Suite 500
Anchorage, AK, 99503
USA
Attn: Paul Berkshire
Annette Island Hydro Project Vertical 6-Jet Pelton
Dear Paul,
Thank you for your continued interest in the supply of Gilkes equipment. Please find herein our budget
offer for the supply of hydroelectric equipment for the above project.
Based on the heads and flows given we have produced a turbine selection that we have every
confidence will meet your requirements. We are providing you pricing based on the confirmations
you provided in your April 27th, 2017 email. Our quoted package includes for a complete water-to
wire package.
As your project develops we would be more than happy to provide you with a more comprehensive
offer tailored to your specific requirements.
We hope you find our budget offer of interest. Should you have any questions or require any further
information or a greater level of detail, please do not hesitate to contact me and I will assist
accordingly.
Yours Sincerely,
Darren Wager
Sales Director Gilkes Hydro
Gilbert Gilkes & Gordon Ltd.
Mobile: +1 (253) - 318-0005
Email:d.wager@gilkes.com
In all alternatives, Gilkes engineers offer the benefit of our experience in providing hydroelectric
equipment for small hydro projects world-wide in the recommendations we make to our clients.
and which we are confident will give many years of trouble free op
Every hydro project supplied by Gilkes is subject to the attentions of a team of highly qualified
engineers including a contract manager, degree qualified mechanical engineer, draughtsperson and
the sales engineer whom you will be dealing with throughout the tender stage. We believe that this
approach ensures that your needs are fully understood by the whole of the Gilkes team during the life
of your contract with us. Your sales engineer becomes your representative inside Gilkes and, should
you not receive 100% best attention from the rest of the team, will be happy to take up any issue you
may have with the way your contract is being handled on your behalf and report back to you
however this is very rare in our experience.
esign our hydroelectric equipment with the benefit of real experience gained
during over 16 projects
In our experience it is always better to design for, rather than close our minds to, possible failure
modes. We therefore accept that it is necessary for turbines to reach full run-away speed safely and
have generators supplied to us tested at full run-away speed to ensure that no damage will occur.
Some suppliers use lower cost generators which will handle 130% or 140% of normal speed and hope
to be able to shut their systems down before the turbine has accelerated to full run-away, and accept
that if the machine does ever reach full run-away the generator will be damaged. Gilkes experience is
that full run-away is usually reached in less than 5 seconds and is therefore extremely difficult to avoid.
The Gilkes Package
We believe that Gilkes' reputation for service during a contract and after sales is well established and
that our sub-contractors are selected because of their proven reliability. A Gilkes equipment package
is comprehensive and exclusive of hidden extras;
All factory assemblies which are stripped down for shipment are witness marked and colour
coded to assist on site assembly.
All major sub-contracted equipment is sourced from established suppliers from our approved
supplier list. These sub-contractors have proved to be high quality, reliable suppliers with a
technical appreciation and experience of small hydro generation projects, on previous
contracts
All foundation bolts, blocks, soleplates, lifting eyebolts are included.
A comprehensive supply of packing shims essential for site installation are included
Prices include packing of all equipment suitable for transport to site.
Comprehensive installation and operating manuals are included.
A Gilkes' project team is delegated to engineer the contract from start to finish and customer
"single line" contact through a contract engineer is organised.
The delivery schedule is handled by Gilkes' product control department and all sub-
contractors are closely monitored to ensure on time delivery of all equipment.
You will note from the above that Gilkes do not just offer a manufacturing service but a complete
specializ n the small hydro industry. This
service ensures that projects proceed smoothly and on time, with the minimum of project
management and/or engineering design/consultancy services
, quality equipment along with the experienced technical engineering
experience that in the long term quality is an important requirement for a small hydro
The Gilkes Pelton Turbine
Pelton turbines are medium to high head free jet impulse turbines. The jet strikes the splitter edge of
the double bucket and is turned through an angle of nearly 180 degrees before falling under gravity
into the discharge channel or tailrace.
reaction turbines do not rely upon maintenance of close operational clearances for
As an impulse machine, The Pelton Wheel has a fairly flat efficiency profile over a typical site
operational envelope. This contrasts with reaction machines where the comparable efficiency profiles
have a fairly prominent peak and thus effective utilisation of available water is compromised,
particularly in installations where the flow varies over a wide range during the year.
For over thirty years Gilkes has been supplying multi-jet vertical Pelton turbines with our most noted
ones highlighted below
1985 1050 P316_4 Jet @ 720rpm 7,318kW Output CA, USA
2009 1435 P346_6 Jet @ 450rpm 15,400kW Output AK, USA
2015 950 P346_5 Jet @ 750rpm 7,015kW Output Turkey
Scope of Supply
1 off 1250 P324 Six-Jet Vertical Pelton Wheel Turbine. Spear valves and deflector mechanisms
fitted with hydraulic actuators.
1 off Set of inlet pipework up to the inlet flange of the Turbine Shutoff Valve including the
upstream transition inlet pipe that attaches to the incoming penstock to the powerhouse
(inclusive of inlet manifold, branch pipes and dismantling joint)
1 off Main inlet valve, double flanged butterfly valve, weight to close, hydraulic actuator to open
1 off 60Hz, 300 rpm (24 pole) generator with the turbine runner connected to the turbine shaft
by means of an overhung arrangement
1 off Generator lube oil and lube oil cooling system
1 off Hydraulic Control Module to control the actuators on the inlet valve, spear valves and
deflectors
1 off Installation supervision of Gilkes supplied equipment
1 off Commissioning supervision of Gilkes supplied equipment
Technical data
The technical data given in this quotation, unless specifically guaranteed, will be subject to
confirmation in the event of an order.
Model : 1250 P324 Six-Jet Vertical Pelton
No. of Units : 1
Mean Diameter of Runner : 1250 mm
Bucket Width Modifier : 100%
Rated Speed : 300 rpm
Maximum Overspeed * : 570 rpm
Maximum Continuous Overspeed Period : 5 minutes in any 24-hour period
Runner Material : CA6NM or equivalent Stainless steel
Shaft Orientation : Vertical
Design Rating (Per Unit)
Static Head : 344 ft
Rated Net Head at Design Flow : 320 ft
Design Flow : 120cfs
Turbine Mechanical Output at Design
Flow
: 2,886 kW
Turbine Shaft Peak Mechanical Efficiency
at Design Head and Flow
: 88.90 %
Performance Curve
The following hill chart and performance curve shows the turbines mechanical shaft power (kW) and
efficiency (%) as a function of head (ft) and flow (cfs).
Price Schedule
Item Qty Description Price ($USD)
1 1 Gilkes 1250 P324_6J Vertical Pelton Impulse Turbine Included
Case
Runner
Bearing housing
Spear valves and actuators
Deflectors and actuators
Inlet manifold
Shims and tools
2 1 Main inlet valve Included
3 1 Generator Included
4 1 Control panel and switchgear panel Included
5 1 Generator lube oil and lube oil cooling system Included
6 1 Hydraulic Control Module Included
7 1 Installation Supervision of Gilkes supplied equipment Included
8 1 Commissioning Supervision of Gilkes supplied equipment Included
TOTAL BUDGET PRICE $USD DOLLARS $2,,
All figures are exclusive of local, State, and Federal which will be charged where applicable. Import
duties and delivery to project site is included.
This pricing is indicative only and is based on the information made available to us prior to the date
of this offer. None of the prices are fixed or firm and will be subject to further review by Gilkes
should you wish to proceed with placing an order.
Please note that this budget offer is not intended to form a legally binding relationship and Gilkes is
not bound to accept purchase orders against this proposal.
Exclusions
We have not included the following items which are required for our equipment due to these being
best supplied locally.
All civils works including sealing of cable ducts
Cable study, protective relay study, secondary injection testing to prove relay study
All powerhouse cabling and conduit routing
All on-site crane hire and lifting arrangements for the equipment
Building Services
Grounding services and termination points including grounding mat
Broadband connection/phone line for any remote communication
HV Switchgear
Transformer
Extent of Supply
The supply of Gilkes plant terminates at the following points;
Turbine inlet - at the upstream end of the main inlet valve
Turbine discharge at the turbine case discharge skirt
Electrical at the LV side of the switchgear terminal connectors
Grounding system at the powerhouse grounding mat (installed by others)
Turbine Description & Material Specification
Pelton Runner: 13/4 Chrome Steel to BS 3100 425 C1; ASTM 473 S41500; A743 CA6N; EN 1.4313 or
similar. The runner will of one piece construction: CNC machined from a fully heat treated forged disc
with hand polished buckets. Statically balanced to ISO 1940 (1973) Grade 6.3
Turbine Case: Fabricated carbon steel plate. BS 4360-43A (similar to ASTM A516 GR 70). Fabricated
in two flanged sections complete with external stiffeners and lifting lugs. Shot blasted, prime and finish
painted.
Turbine Shaft and Bearing Assembly: The Runner is mounted on a BSEN 10083-3 42CrMo4 turbine
shaft and secured by a bolted flange arrangement. The shaft extends through a seal assembly and is
supported by two sleeve bearings, pedestal mounted, suitable for forced feed lubrication. The
bearings are fitted with PT100 type resistance temperature detector (RTD) for monitoring purposes.
Shaft Seal: Labyrinth type incorporating catchment chamber and drain pipe.
Jet Deflector: 13/4 chrome-nickel corrosion resistant cast steel. BS 3100 Grade 425 C11 (similar to
ASTM A743 GR CA 6NM). The jet deflector mechanism is fitted inside the turbine case and is
operated by an externally mounted hydraulic actuator driven from a HPU. The deflector will engage
the jet stream in response to signals from the control system provided by you.
Branchpipe: Fabricated carbon steel, BS 4360-43A (similar to ASTM A516 Gr. 70). The needle valve
pipe is a flanged bend designed to direct the jet stream through the jet nozzle. The needle valves
are regulated by hydraulic actuators.
Spear Tip: 13/4 chrome-nickel corrosion resistant cast steel. BS 3100 Grade 425 C11 (similar to ASTM
A743 GR CA 6NM). The needle valve tips are screwed and riveted to the needle valve rods to allow
easy replacement, if necessary.
Spear Rod: Martensitic chrome-nickel rust resisting steel. BS 970431.S29 (similar to ASTM A473 431)
Spear Rod Support: Cast gunmetal, BS 1400 LG4-2 (similar to ASTM B145-4A). The needle valve rod
support is mounted between the nozzle holder and needle valve pipe.
Nozzle Plate/Seat: 13/4 chrome-nickel corrosion resistant cast steel. BS 3100 Grade 425 C11 (similar
to ASTM A743 GR CA 6NM). The jet nozzles are flanged and bolted to the nozzle holders with stainless
steel fixings to allow easy replacement, if necessary.
Nozzle Holder: Ductile SNG iron, BS 2789 SGC1.420/12 (similar to ASTM A436 Type D2). The jet
nozzle holder is mounted on the turbine case and is flanged for connection to the needle valve pipe.
Foundation Bolts: All necessary foundation bolts plus a generous supply of packing pieces for
installation setting up purposes are included.
Example Drawing
The following example drawing shows the typical layout of a P43 -Jet Vertical Pelton
Turbine. Please note these drawings are intended for information purposes only and should not to
be relied upon for construction. It is also our closest previously manufactured size to the unit being
quoted here.
Payment Terms
Unless otherwise agreed, the following payment terms apply:-
10 % of total contract price with order
30 % of total contract price on presentation of the following drawings
-General arrangement
-Foundation details to allow civil works to proceed
10 % of total contract price on presentation of runner material certificates.
40 % of total contract price on readiness of equipment to ship to site, or on notification of
readiness to ship, if site is unable to receive goods. Storage charge can be applied if
delivery is delayed by more than 3 months.
10 % of total contract price due on Completion of Commissioning, or 4 months after delivery
to site, or 6 months after notification of readiness to ship, whichever is the sooner.
If Commissioning of Turbine is to be by others then final payment due on shipping.
All payments net 30 Days from date of invoice.
Estimated delivery
All equipment will be delivered to site provided that access is available to standard road transport.
The equipment will only be delivered to site if the site is in a complete and fit state to receive the
goods.
We estimate the delivery for the equipment offered in our quotation to be 50 Working Weeks, CIF
Incoterms ® 2010; from receipt of an official order complete with full and final instructions to proceed
and on receipt of any initial stage payment.
Deliveries offered are indicative only. Firm delivery periods are dependent upon contract start dates,
and are subject to Gilkes' factory work loading and major casting availability at the contract start date.
Firm delivery periods will be reviewed at time of order.
Production, Inspection and Quality Control
Production, Inspection and Quality Control will be to Gilkes standard practice as detailed in the Gilkes
Quality Manual and Production Control System Manual which are available on request and in
accordance with our Quality Management System accredited to ISO 9001:2008. Unless otherwise
stated all equipment offered is to Gilkes standard specification.
Warranty
Gilkes offer a warranty period of 12 months from completion of commissioning or 18 months from
delivery; whichever is the sooner. Gilkes must present in a supervisory capacity at the installation and
commissioning for the warranty to be effective applied.
Insurances
Insurance cover in relation to this contract is as Gilkes standard insurances. Details are available upon
request.
Contract Conditions
A copy of our standard contract conditions can be made available on request and will need to be
included, and or negotiated prior to any contract being signed for this potential project.
From:Berkshire, Paul
To:Berkshire, Paul
Subject:Triangle Lake Canyon Estimate
Date:Tuesday, July 25, 2017 10:57:52 AM
From: Brett Bauer [mailto:brett.bauer@canyonhydro.com]
Sent: Thursday, April 27, 2017 2:02 PM
To: Berkshire, Paul <Paul.Berkshire@hdrinc.com>
Subject: RE: Triangle Lake Budgetary Estimate
Hello Paul,
Thank you for the opportunity to assist with this project. For a net head of 320 feet and a design
flow rate of 120 ft3/s, we have considered three primary options:
Vertical five jet Pelton
Horizontal two jet Turgo
Horizontal shaft Francis
You understand all the pros/cons of these choices, but a few highlights are:
Pelton would give you the broadest efficient operating range with great ability to govern without
penstock surges, at the expense of a tall powerhouse and slight increase in equipment cost.
The Turgo also gives great ability to govern but is less efficient.
The Francis has the smallest footprint but a peaked performance curve and requires penstock design
considerations.
For the Pelton, we propose the following scope:
Canyon five jet vertical axis Pelton turbine, 300 rpm-2.8MW generator, TIV, HPU, LPU,
switchgear/controls. Budget estimate for Pelton package as described is $2,140,000.00.
For the Turgo, we propose the following scope:
Canyon two jet horizontal axis Turgo turbine, 450 rpm-2.7MW generator, TIV, HPU, LPU,
switchgear/controls. Budget estimate for Pelton package as described is $1,850,000.00.
For the Francis, we propose the following scope:
Canyon horizontal axis Francis turbine, 720 rpm-2.9MW generator, TIV, HPU, LPU,
switchgear/controls. Budget estimate for Francis package as described is $2,080,000.00.
Note: runaway discharge is estimated to be 59 ft3/s.
I hope this rough comparison is helpful as you study the project feasibility. Please contact me if you
have any questions.
Best regards,
Brett
Brett Bauer | Canyon Hydro – V.P. Engineering | brett.bauer@canyonhydro.com | 1-360-592-5552
12005 N. Burgard, Portland, OR 97203
Phone: (503) 285-1400, (800) 824-9824
Fax: (503) 382-2327
To: Date:
Phone: Project:
Quotation No.
Email:
Budgetary Quotation
SPECIFICATIONS:
Pipe:
Length:
Joints:
Coating:
Lining:
Freight:
Delivery:
Fabrication:
Currency:
Qty.OD Wall Yield Working D/T Unit Price Extension
Item (lf)(in)(in.)(psi)Pres.(psi)Ratio $/lf Total $
For Further Information:
Sales Representative
Jeffrey S. Curl