HomeMy WebLinkAboutCommunity of Elfin Cove Hydroelectric Project Iterim Hydrology Report - Dec 2013 - REF Grant 7040043polarconsult alaska, inc.
1503 West 33rd Avenue, Suite 310
Anchorage, Alaska 99503-3638
Phone: (907) 258-2420
FAX: (907) 258-2419
I N T E R I M H Y D R O L O G Y R E P O R T
131220-INTERIMHYDROLOGYREPORT.DOC
DATE: December 20, 2013
TO: Jane Button, ECUC Project Manager
FROM: Joel Groves, PE Polarconsult Project Manager
SUBJECT: Interim Hydrology Report, Crooked Creek and Jims Lake Hydro Project
CC:
1. Background
From 1984 to 1985, the Alaska Department of Natural Resources (ADNR) maintained stream
gauges at the proposed Crooked Creek diversion site and Jim’s Lake outlet. Since 2008, Elfin
Cove Utility Commission (ECUC) has maintained stream gauges at these same two locations.
Additionally, ECUC maintained a stream gauge at Roy’s Creek from October 2009 through June
2012.1 The installations and station histories through June 2011 are described in detail in
Appendix C of the Crooked Creek and Jim’s Lake Hydroelectric Feasibility Study Final Report
(Polarconsult, June 2011). More recent station histories are provided in this interim report.
The Crooked Creek and Jim’s Lake gauging stations are both still maintained and operating as of
the most recent data download. This interim report provides up to date information on the
stations and collected hydrology information, and provides an interim analysis of the collected
hydrology data. The findings presented in this interim report are used to update the project
analysis completed in the 2011 Feasibility Study in order to recommend a project configuration
for final design and permitting.
2. Summary of Findings
The on going hydrology study has produced 2.56 years of flow data at Crooked Creek and 4.24
years of data at Jim’s Lake. Correlations between these sites and the discontinued Roy’s Creek
gauge are used to produce an extended hydrology record for both sites of 5.32 years.
Analysis of the current data indicate lower flows at both Crooked Creek and Jim’s Lake than
indicated by the analysis completed for the 2011 Feasibility Study. Current estimates for the
median flow
2 at both sites are approximately 80 to 85% of the estimates in the 2011 Feasibility
Study.
Analysis of these data indicate that the resource capacity factor of Crooked Creek, the major
water supply for the proposed development, is between 52 and 55% at a design flow of 5 cubic
feet per second (cfs). The hydrology analysis in the 2011 Feasibility Study estimated the
resource capacity factor for this design flow at between 50 and 61%. Resource capacity factor
for Jim’s Lake is not meaningful because the storage capacity of the lake can capture
substantially all of the flow for power generation.
1 Roy’s Creek is not currently under consideration for hydroelectric development, but was evaluated in the 2010
Hydroelectric Reconnaissance Study for Elfin Cove. Roy’s Creek data is included in this interim report because it
is used to extend the record for the Crooked Creek gauging station.
2 Median flow is the 50% exceedance flow in Figures 6 and 7.
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 2 OF 10
2008
2009
2010
2011
2012
2013
2014
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Crooked Creek Gauged Flow
Jim's Lake Gauged Flow
Roy's Creek Gauged Flow
3. Available Hydrology Data
From the start of stream gauging efforts in June 2008 to June 2009, and again from June 2011
to April 2013, ECUC led stream gauging efforts. From June 2009 through June 2011, and April
2013 to the present time, Polarconsult has been under contract to ECUC to conduct stream
gauging. ECUC has provided all available hydrology records and field data to Polarconsult.
Polarconsult has consolidated all available records and data for analysis. Currently available
hydrology data is summarized in Table 1 and Figure 1. Currently, 2.56 years of data have been
collected at Crooked Creek, 4.24 years of data at Jim’s Lake, and 2.42 years at Roy’s Creek.
Figure 1 presents the stage record collected at both stations. Gaps in Figure 1 reflect stage data
that was not recorded either due to failure of the logger hardware or insufficient memory
capacity. All flow measurements completed at these stations are summarized in Table 2.
Table 1: Summary of Hydrology Data for Elfin Cove Hydroelectric Resources
Location Basin Size
(sq.mi.)(1)
Site Elevation
(ft)(1)Latitude (1)Longitude (1)Begin Date End Date
Number of
Records (days)
(3)
7/6/84(2)2/13/85(2)202Crooked Creek
at diversion site
0.56 478.0 58 10'40" 136 19'16"8/22/08 Current
(3)933
7/6/84(2)2/11/85(2)202Jim's Lake Creek
at lake outlet
0.10 333.2 58 10'34" 136 19'32"8/22/08 Current
(3)1,547
Roy’s Creek
above Falls
0.42 470 58 11'29" 136 20'09" 10/8/09 7/8/12 885
(1) Data from June 2011 Feasibility Study, Appendix C.
(2) Count of available daily records. Gauges may have been in service for a longer period.
(3) The record count for current gauging stations reflects data through the most recent download on December
17, 2013 at Crooked Creek and October 17, 2013 at Jim’s Lake. The Roy’s Creek gauge has been discontinued.
Figure 1: Summary of Data Available from Gauging Stations
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 3 OF 10
Table 2: Flow Measurements at Jims Lake, Crooked Creek, and Roys Creek Gauging Stations
Local Date/Time Party Flow (cfs) Stage (ft) Method / Equipment
Crooked Creek at Diversion Site
7/26/2008 15:15 Button/ Christensen 2.33 7.7 Pygmy Meter
(2)
7/27/2008 16:20 Button/ Christensen 4.35 7.76 Pygmy Meter
8/22/2008 14:30 Button/ Christensen 5.38 7.92 Pygmy Meter
6/1/2009 11:39 Button/ Christensen 4.17 7.73 Pygmy Meter
6/28/2009 16:40 Button/ Christensen 1.3 7.6 Pygmy Meter
7/9/2009 10:55, 11:20 Groves/ Hertrich 0.98 / 0.94 7.54 Hanna Meter
(3)
9/4/2009 11:15, 11:40 Groves/ Glendoing 0.84 / 0.93 7.54 Hanna Meter
10/9/2009 12:50 Groves/ Christensen 3.71 7.68 Hanna Meter
12/9/2009 13:45 Button/ Christensen 1.07 7.52 Hanna Meter
8/10/2010 11:40, 12:15 Groves/ Button 2.41 / 2.25 7.62 Hanna Meter
9/27/2011 17:00 Christensen 1.42 7.55 HOBO Meter
(4)
6/8/2013 13:20, 13:50 Christensen 7.36 / 7.48 7.81 HOBO Meter
7/15/2013 17:30, 17:45 Groves 0.69 /0.88 7.48 Hanna Meter
10/17/2013 10:00, 10:40 Groves 1.42 / 1.38 7.52 Hanna Meter
Crooked Creek at Mouth
10/17/2013 15:00 Groves 1.96 NA Hanna Meter
Jims Creek at Lake Outlet
(5)
7/25/2008 12:30 Button/ Christensen 3.42 4.18 Pygmy Meter
7/26/2008 10:45 Button/ Christensen 1.3 3.82 Pygmy Meter
8/22/2008 12:45 Button/ Christensen 0.11 3.7 Pygmy Meter
6/1/2009 10:00 Button/ Christensen 0.54 3.73 Pygmy Meter
6/28/2009 18:00 Button/ Christensen 0.04 3.61 Pygmy Meter
7/9/2009 12:15, 12:30 Groves/ Hertrich 0.091 / 0.091 3.56 Hanna Meter
9/4/2009 10:00, 10:15 Groves/ Glendoing 0.219 / 0.217 3.52 Hanna Meter
10/9/2009 13:45 Groves/ Christensen 0.44 3.62 Hanna Meter
10/9/2009 14:05 Groves/ Christensen 0.44 3.69 Hanna Meter
12/9/2009 14:15 Button/ Christensen 0.219 3.68 Hanna Meter
8/10/2010 10:30, 10:45 Groves/ Button 0.421 / 0.422 3.72 Hanna Meter
9/27/2011 16:15 Christensen 0.34 3.69 HOBO Meter
6/8/2013 14:45 Christensen 0.33 3.67 HOBO Meter
7/15/2013 16:30 Groves 0.17 /0.20 3.48 Hanna Meter
10/17/2013 13:30 Groves 0.25 /0.26 3.69 Hanna Meter
Roys Creek Above Falls
9/3/2009 Groves 1.10 NA Hanna Meter
10/8/2009 16:51 Groves 3.26 1.27 Hanna Meter
12/9/2009 11:45 Button/ Christensen 0.68 1.09 Hanna Meter
8/13/2010 11:30 Groves/Button 1.29 1.17 Hanna Meter
7/18/2013 17:20 Groves 0.59 1.12 Hanna Meter
(1) Current velocity stream flow method with March McBirney current velocity meter (model unknown).
(2) Current velocity stream flow method with Pygmy current velocity meter.
(3) Sudden dose salt integration stream flow method with Hanna HI 9828 conductivity meter.
(4) Sudden dose salt integration stream flow method with Hobo U24 001 conductivity logger.
(5) A small weir was installed on October 9, 2009, to stabilize and improve the section at the gauge.
‘‘ Indicates data are not available.
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 4 OF 10
4. Recent Gauging Station Histories
3
Crooked Creek Diversion Site Gauging Station
September 27, 2011.The gauging station was downloaded and stage and flow were
measured. The on board temperature sensor was found to be malfunctioning.
July 10, 2012.The data logger was found submerged in the creek downstream of the
gauging station, apparently ripped off the tree by a bear. The logger was not recovered at
this time.
June 8, 2013.The destroyed data logger was recovered from Crooked Creek and stored in
Elfin Cove. Stage and flow were measured. A new data logger and pressure transducer (PT)
was installed at the same gauging station. The new data logger is a cellular enabled GSM 2
manufactured by Keller America, Inc. It transmits site telemetry to Polarconsult every four
hours via cellular GSM network. The new PT is a Keller Acculevel vented transducer.
July 15, 2013.Stage and flow were measured.
October 17, 2013.Anomalies in programming of the GSM 2 were corrected by direct cable
interface in the field. The PT installed in June was determined to be providing spurious
stage data, and was replaced with a new PT of the same make and model. Stage and flow
were measured.
October 29, 2013.Polarconsult extracted the main board from the data logger found
destroyed in July 2012 and returned it to the manufacturer to attempt to recover the data.
The manufacturer found no valid data on the memory chip and the main board was not
salvageable.
Lake Outlet Gauging Station
Sept. 27, 2011.The gauging station was downloaded and stage and flow were measured.
July 10, 2012.The gauging station was downloaded and stage was measured.
June 8, 2013.The gauging station was downloaded and stage and flow were measured.
July 15, 2013.The gauging station was downloaded and stage and flow were measured.
Oct. 17, 2013.The gauging station was downloaded and stage and flow were measured.
Creek Gauging Station
July 10, 2012. Station hardware was removed. Stage was measured.
July 18, 2013.Stage and flow were measured.
3 For earlier station history, see June 2011 Feasibility Study, Appendix C.
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 5 OF 10
7.30
7.40
7.50
7.60
7.70
7.80
7.90
8.00
0 2 4 6 8 10 12
Flow (cfs)
Accepted Measurements, 2008 11
Accepted Measurements, 2013
S D Curve(2011 Feas. Study)
S D Curve, 2013 (Current)
S D Curve, 2008 2012 (Current)
5. Hydrology Analysis
Station Rating Curves
All available flow and stage measurements were reviewed and used to develop updated
stage discharge curves for each gauging station. Rating curves developed in the 2011
Feasibility Study are also shown for comparison.
Data, rating curves, and equations for the Crooked Creek station are presented in Figure 2.
Data for the Crooked Creek gauging station indicate the creek section was stable from 2008
to 2012. It appears that a flood event prior to June 2013 may have changed the section
slightly, based on field conditions and 2013 flow measurements. The 2013 curve was
shifted to the right to reflect these data.
Figure 2: Stage Discharge Curves for Crooked Creek Gauging Station
Data, rating curves, and equations for the Jim’s Lake station are presented in Figure 3. The
outlet section at Jim’s Lake is generally stable, however the stage discharge relationship
appears to be more variable than at Crooked Creek. This greater variability is attributed to
the very low flows being gauged at Jim’s Lake. These low flows, often just a few tenths of a
cfs, introduce two challenges for a natural channel gauging station: accurately measuring
such low flows taxes the capabilities of most flow measurement techniques; and the stage
discharge relationship at such low flows can be significantly perturbed by transient events
such as leaves sticking to rocks in the creek bed near the gauge. Errors in measuring the
small flows at Jim’s Lake are not expected to adversely affect project development
decisions.
2008 2012: Q = 28.0 (S 7.40)1.6
2013: Q = 26.5 (S 7.36)1.6
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 6 OF 10
Figure 3: Stage Discharge Curves for Jims Lake Outlet Gauging Station
Data, rating curve, and equations for the Roy’s Creek station are presented in Figure 4. The
creek section at Roy’s Creek appears to have been stable over the 2.8 year period when the
gauge was installed.
Figure 4: Stage Discharge Curves for Roys Creek Gauging Station
3.40
3.50
3.60
3.70
3.80
3.90
4.00
4.10
4.20
4.30
0 0.5 1 1.5 2 2.5 3 3.5 4
Flow(cfs)
All Measurements, 2008 13
S D Curve, Current, +0.07'Stage Shift
S D Curve, Current
S D Curve, Current,0.07'Stage Shift
S D Curve(2011 Feas. Study, 10/9/09 5/9/11)
S D Curve(2011 Feas. Study, 2008 10/9/09)
8/22/08 to 8/16/09:Q = 3.6 (S 3.27)3.0
8/16/09 to 8/29/09; 10/9/09 to current:Q = 3.6 (S 3.20)3.0
8/29/09 to 10/9/09: Q = 3.6 (S 3.13)3.0
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
1.80
0 1 2 3 4 5 6 7 8 9 10Flow (cfs)
AllMeasurements, 2009 2013
S D Curve(2011 Feas. Study)
S D Curve(Current Analysis)
Full Record:Q = 35.1 (S 0.93)2.29
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 7 OF 10
0
1
2
3
4
5
6
7
8
9
10
Jan Feb Mar Apr May Jun Jul Sep Oct Nov Dec
2008
2009
2010
2010
2011
2013
Station Hydrographs
Recorded stage data and manual stage readings for all three stations were reviewed.
Apparent errors due to sensor anomalies and gross errors due to ice effects were corrected.
Further revisions to the stage record to reflect more subtle ice effects on the stage record
during the winter season (generally November – March) at all stations may be warranted.
The resulting hydrographs for the three gauging stations are presented in Figures 3, 4 and 5.
Figure 3: Crooked Creek Hydrograph, 2008 2013
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 8 OF 10
0
1
2
3
4
5
6
7
8
9
10
Jan Feb Mar Apr May Jun Jul Sep Oct Nov Dec
2009
2010
2011
2012
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2008
2009
2010
2010
2011
2011
2012
2013
Figure 4: Jims Lake Outlet Hydrograph, 2008 2013
Figure 5: Roys Creek Hydrograph, 2009 2012
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 9 OF 10
Record Extensions
As shown in Figure 1, there are significant gaps in the record set for all three gauging
stations. The two year long gap at Crooked Creek from September 2011 to October 2013 is
of particular significance as Crooked Creek is the prime water supply for the proposed
hydroelectric project.
Correlations between the three gauges were analyzed and used to fill in gaps in the Crooked
Creek and Jim’s Lake records. Table 3 summarizes the coefficients of determination and
correlation equations used for the record extensions.
4 The coefficient of determination
between Crooked Creek and Roy’s Creek (R
2 = 0.83) is high, which is expected given the
proximity and similar basins of these two creeks. The coefficient of determination between
the Jim’s Lake outlet site and the two creeks is significantly lower (R
2 = 0.31), which is also
expected because the lake moderates flows from this basin.
Missing records for Crooked Creek are supplemented first by Roy’s Creek data, second by
Jim’s Lake data, and lastly by the average daily flow for the missing data at Crooked Creek.
Missing records for Jim’s Lake are supplemented first by Roy’s Creek data, second by
Crooked Creek data, and lastly by the average daily flow for the missing data at Jim’s Lake.
Table 3: Correlation Equations for Crooked Creek and Jims lake Record Extensions
Site Correlation Source
Days of Common
Record
Coefficient of
Determination Correlation Equation
Roy’s Creek Gauge 600 0.83 QCC = 0.822 QRC
1.40
Crooked Creek Jim’s Lake Gauge 871 0.31 QCC = 3.26 QJL + 1.63
Roy’s Creek Gauge 827 0.46 QJL = 0.0414 QRC +0.324Jim’s Lake Crooked Creek Gauge 871 0.31 QJL = 0.0947 QCC +0.255
QCC: Flow at Crooked Creek gauging station, cfs
QRC: Flow at Roy’s Creek gauging station, cfs
QJL: Flow at Jim’s Lake gauging station, cfs
Table 4 summarizes the data sources used to compile the extended records for the Crooked
Creek and Jim’s Lake sites.
Table 4: Data Sources for Crooked Creek and Jims Lake Extended Records
Data Source Crooked Creek Site Data Source Jims Lake Site
Crooked Creek Gauge 2.56 years Jims Lake Gauge 4.24 years
Roy’s Creek Gauge 0.78 years Roy’s Creek Gauge 0.16 years
Jim’s Lake Gauge 1.23 years Crooked Creek Gauge 0.17 years
Average Daily Data for Site 0.75 years Average Daily Data for Site 0.75 years
Total Extended Record 5.32 years (August 22, 2008 to December 17, 2013)
4 The coefficient of determination is a statistical measure of how related two data sets are. The coefficient’s value ranges from
zero to one, with zero representing no relationship between the two data sets, and one representing a perfect correlation.
C ROOKED C REEK AND J IM ’S L AKE H YDROELECTRIC P ROJECT
I NTERIM H YDROLOGY R EPORT P OLARCONSULT A LASKA ,INC .
DECEMBER 20,2013 PAGE 10 OF 10
0
1
2
3
4
5
6
7
8
9
10
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Time Flow is Equalled or Exceeded
8/22/2008 10/17/2013 Gauged Flow (Current Analysis)
8/22/2008 10/17/2013 Extended Record (Current Analysis)
8/22/2008 5/9/2011 Data (2011 Feas. Study Analysis)
1984 85 Data (2011 Feas. Study Analysis)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Time Flow is Equalled or Exceeded
8/22/2008 10/17/2013 Gauged Flow (Current Analysis)
8/22/2008 10/17/2013 Extended Record (Current Analysis)
8/22/2008 5/9/2011 Data (2011 Feas. Study Analysis)
1984 1985 Data (2011 Feas. Study Analysis)
Flow Duration Curves
Figures 6 and 7 present flow duration curves for the Crooked Creek and Jim’s Lake sites.
The figures also show the 2011 Feasibility Study curves for comparison.
The current flow duration curves for Crooked Creek calculated from gauged flow and the
extended record are similar. Both current curves are lower than the estimated curve from
the 2011 Feasibility Study, and higher than the estimated curve from the 1984 85 data.
Figure 6: Crooked Creek Flow Duration Curve, 2008 2013
The current flow duration curves for Jim’s Lake calculated from gauged flow and the
extended record are very similar, and also fall between the previous curves.
Figure 7: Jims Lake Outlet Flow Duration Curve, 2008 2013