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Home My WebLink About100915-TripReportpolarconsult alaska, inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503-3638 Phone: (907) 258-2420 FAX: (907) 258-2419 T RIP R EPORT 100915-TRIPREPORT.DOC DATE: 9/15/2010 TO: Jane Button, Non-Profit Community of Elfin Cove (CEC) FROM: Joel Groves, P.E. RE: August 9 to 14 Trip Report CC: Project File PURPOSE AND BACKGROUND The CEC retained Polarconsult Alaska, Inc. (PCA) to conduct reconnaissance and feasibility studies of hydropower resources for Elfin Cove in 2009. PCA provided CEC the completed reconnaissance study in March 2010, and CEC selected a project at Crooked Creek and Jim’s Lake for feasibility assessment in May 2010. This field visit was performed to collect additional field data necessary to complete a feasibility study of a hydroelectric project at Crooked Creek and Jim’s Lake. FIELD ACTIVITIES Polarconsult engineer Joel D. Groves, P.E. mobilized from Anchorage to Elfin Cove on August 9th, 2010. Primary objectives of the trip were: 1. Perform maintenance on the stream gauges, including downloading data, upgrading power supplies, and measuring stream flows. 2. Collect more detailed data at the diversion sites on Crooked Creek and Jim’s Lake, penstock routes, and powerhouse sites. SCHEDULE The feasibility study will be completed and a draft issued to CEC for review and comment by November 1st. Polarconsult will finalize the feasibility study 30 days after receipt of CEC comments. ACTION ITEMS Stream Gauging Maintenance 1. The gauging stations at Roy’s Creek and Crooked Creek will need new power supplies before this winter. Because of inadequate ambient light at the gauge locations, solar power has been excluded as a suitable solution. Polarconsult will provide new batteries for the stations. 2. High flow measurements at all three gauging stations would be useful to improve station calibrations. Polarconsult has furnished the CEC with a HOBO conductivity data logger and sufficient salt to complete these measurements. Polarconsult will coordinate with CEC to complete these measurements this October. 3. The Roy’s Creek desiccant canister needs to be refreshed. This should occur before winter. POLARCONSULT TRIP REPORT ELFIN COVE HYDRO FEASIBILITY STUDY SEPTEMBER 15, 2010 PAGE 2 OF 4 2008-10 Crooked Creek Stage Data 7.4 7.6 7.8 8.0 8.2 8.4 8.6 8.8 9.0 9.2 9.4 8/1/08 11/1/08 2/1/09 5/4/09 8/4/09 11/4/09 2/4/10 5/7/10 8/7/10 Measured Stage Recorded Stage (2008-09) Recorded Stage (2009-10) STREAM GAUGES Stream gauges are installed at the Crooked Creek intake site, Roy’s Creek intake site, and at the outlet of Jim’s Lake. Stream flow measurements made this trip are summarized in Table 1. Table 1: Flow Measurements Date/Time Method Location Flow (cfs) Stage at Gauge (ft) 8/10/10 10:35 Sudden salt dose Jim’s Lake - 15 yds below gauge 0.421 3.73 8/10/10 10:47 Sudden salt dose Jim’s Lake - at gauge 0.422 3.73 8/10/10 11:37 Sudden salt dose Crooked Creek - at gauge 2.41 7.62 8/10/10 12:17 Sudden salt dose Crooked Creek - 30 yds ab. gauge 2.25 7.62 8/13/10 11:30 Sudden salt dose Roy’s Creek - 10 yds below gauge 1.05 1.15 8/13/10 12:20 Sudden salt dose Roy’s Creek - at gauge 1.07 1.15 Crooked Creek Intake Site Gauge The Crooked Creek gauge installation and pool where the gauge is inst alled appear unchanged from the last Polarconsult visit in October 2009. Current flow measurements are summarized in Table 1. The station was successfully downloaded. The station is equipped with a Sutron Monitor-4 datalogger powered by 4 D-cell lithium thionyl batteries. The current batteries will be exhausted in approximately January or February 2011. A solar panel was tested during this visit, but received insufficient light to reliably power the data logger. A seven Ah lead acid battery and regulator were installed in the data logger enclosure to support future solar power, but the logger remains on the lithium batteries. New lithium batteries will be shipped to Elfin Cove this fall. The desiccant canister inside the datalogger cabinet was refreshed during this field visit. 2008 – 2010 stage data at the Crooked Creek gauging station is presented in Figure 1. Stage-discharge curves and calculated flow data will be reported in the feasibility study to be issued later this year. Figure 1: Stage Data at Crooked Creek Gauging Station POLARCONSULT TRIP REPORT ELFIN COVE HYDRO FEASIBILITY STUDY SEPTEMBER 15, 2010 PAGE 3 OF 4 2008-10 Jim's Lake Stage Data 3.40 3.60 3.80 4.00 4.20 4.40 4.60 4.80 8/1/08 10/31/08 1/30/09 5/1/09 7/31/09 10/30/09 1/29/10 4/30/10 7/30/10 Recorded Stage Recorded Stage Measured Stage Measured Stage Jim’s Lake Outlet Gauge The Jim’s Lake outlet gauge installation and pool where the gauge is installed appear unchanged from the last Polarconsult visit in October 2009. Current flow measurements are summarized in Table 1. The station was successfully downloaded. The station is equipped with HOBO water pressure and barometric data loggers. These loggers have 5 to 10 year battery lives, and have been in service for approximately 2 years. The barometric data logger is installed in an enclosure with a large can of desiccant to help avoid barometric datalogger problems during freezing weather. This desiccant appears to have successfully prevented the cold weather problems experienced by the barometric datalogger in the winter of 2008 – 2009. The desiccant was refreshed during this site visit. 2008 – 2010 stage data at the Jim’s Lake outlet gauging station is presented in Figure 2. Stage-discharge curves and calculated flow data will be reported in the feasibility study to be issued later this year. Figure 2: Stage Data at Jim’s Lake Outlet Gauging Station POLARCONSULT TRIP REPORT ELFIN COVE HYDRO FEASIBILITY STUDY SEPTEMBER 15, 2010 PAGE 4 OF 4 2009-10 Roy's Creek Stage Data 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 10/1/09 11/1/09 12/2/09 1/2/10 2/2/10 3/5/10 4/5/10 5/6/10 6/6/10 7/7/10 8/7/10 9/7/10 Recorded Stage Measured Stage Roy’s Creek Intake Site Gauge The Roy’s Creek gauge installation and pool where the gauge is installed appear unchanged from the last Polarconsult visit in October 2009. Current flow measurements are summarized in Table 1. The station was successfully downloaded. The station is equipped with a Sutron Monitor-4 datalogger powered by 4 D-cell lithium thionyl batteries. The current batteries will be exhausted in approximately January or February 2011. A solar panel was tested during this visit, but received insufficient light to reliably power the data logger. A seven Ah lead acid battery and regulator were installed in the data logger enclosure to support future solar power, but the logger remains on the lithium batteries. New lithium batteries will be shipped to Elfin Cove this fall. The desiccant canister inside the datalogger cabinet was refreshed during this field visit. 2008 – 2010 stage data at the Crooked Creek gauging station is presented in Figure 3. Stage-discharge curves and calculated flow data will be reported in the feasibility study to be issued later this year. The desiccant canister inside the datalogger cabinet was not refreshed during this field visit. Although the CEC selected the Crooked Creek / Jim’s Lake project for feasibility assessment, Polarconsult will keep the Roy’s Creek gauge in service through the winter of 2010-11 in order to collect an adequate period of record at this creek to support future consideration of this resource. This data will be included as an appendix to the feasibility study. Figure 3: Stage Data at Roy’s Creek Gauging Station DATA COLLECTION Mr. Groves, assisted by Jane Button, completed a survey of key project features in order to index these project features relative to local land boundaries, sea level, and existing utility infrastructure. This will improve the accuracy of information used for the feasibility study. Concurrently, Mr. Groves reviewed prospective penstock routes and access routes from tidewater up to the project as well as overland between the project and Elfin Cove.