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HomeMy WebLinkAbout14035_FalsePassHydro_REF_AEA_QAresponse_03012022polarconsult alaska, inc. 1503 West 33rd Avenue, Suite 310 Anchorage, Alaska 99503-3638 Phone: (907) 258-2420 FAX: (907) 258-2419 M E M O R A N D U M 220301M-UNGAMAN REF AEA Q&ARESPONSE.DOC DATE: March 1, 2022 TO: Karin St. Clair, Alaska Energy Authority FROM: Joel Groves, P.E. SUBJECT: Responses to AEA Review Questions on City of False Pass REF Grant Application for Unga Man Creek Hydro Design and Permitting CC: Nikki Hoblet, Mayor; Project File Alaska Energy Authority (AEA) review questions on the City of False Pass’ (City) REF grant application for design and permitting of a proposed hydro project on Unga Man Creek were forward to Polarconsult on February 27, 2022. This memo answers the AEA review questions. AEA review questions are listed below in bold blue. Polarconsult responses follow in black. DESIGN  A 2016 Feasibility Study Progress Report was provided with the application. AEA would like a copy of the final Feasibility Report. This report is currently being finalized and will be issued in early March 2022. It will be forwarded to AEA via the City when available.  Was there a recent Feasibility Report with cost estimate? Yes, the above-mentioned feasibility study report includes a cost estimate.  The 2015 Reconn Report has design of 125 kW, flow 13 cfs, and assumed instream flow of 2 cfs. The 2016 Feasibility Study Progress Report had design of 140 kW, flow 13 cfs, and assumed instream flow of 5 cfs. Application has design of 180 kW with flow of 18 cfs. This is correct. The above-mentioned 2022 feasibility study report identifies a 180-kW project. Each iteration of project analysis has considered then-available utility load and hydrology data. Electricity load in False Pass has increased significantly over the course of the studies, and optimal project size has increased accordingly.  What document recommends design of 180 kW and flow of 18 cfs? The above-mentioned feasibility study report.  ADF&G Anadromous Fish Catalog has Chum, Pink, Sockeye, and Coho in the by-pass reach. The ADFG catalog listings are based in part on fisheries surveys conducted for this project. Unga Man Creek was not listed in the catalog prior to 2015. Fisheries surveys for this project conducted in August 2015, 2016 and 2017 determined that Unga Man Creek is principally pink salmon habitat, with sockeye and chum also present and only trace presence of coho. The creek is atypical habitat for sockeye and the observed sockeye may be strays from nearby lake systems.  What discussions has False Pass had with ADF&G regarding in-stream flow requirement? P OLARCONSULT M EMORANDUM Page 2 of 3 There have only been limited discussions to date with ADFG at this stage of project development. Fishery survey reports have been transmitted to ADFG and fish survey design coordinated with ADFG to proactively identify and address expected resource questions. Discussions of ISFR specific to the proposed project configuration have not begun.  What is the assumed in-stream flow requirement for current analysis? No ISFR is assumed for the current analysis, but sensitivity analysis in the 2022 report does address the impact of prospective ISFRs. The proposed intake location at RM 1.4 is just above the confluence of the main stem and east forks of Unga Man Creek. East fork flow is approximately 16% of total flow at the intake site, and this flow will remain in the creek regardless of project operations. This may be sufficient to sustain salmon habitat without need for further dedicated in stream flow reservation (ISFR). Current ISFR expectations are based on salmon habitat mapping completed in 2017: 93% of total habitat area is located downstream of the proposed tailrace location, and most of the habitat in the bypass reach is of marginal quality. COST ESTIMATE o Documents gave a 2015 cost estimate based on ~$25,000/kW. That is correct. That is the estimation methodology used in the 2015 reconnaissance study and 2016 feasibility study progress report. It is not the estimation methodology used in the 2022 feasibility study final report. o Application has construction cost of $4.7M. That is correct.  Is there a more current or detailed site specific cost estimate? Yes. The current cost estimate is based on the specifics of the recommended project as presented in the application and the final feasibility study report. o Does cost estimate include funding for construction administration/contingency? Yes, the stated construction budget includes 5% of the direct construction cost for construction administration, 3% for construction engineering, and 25% for overall construction contingency.  Does cost estimate include funding for integrating hydro with diesel power plant? Yes. $75,000 is budgeted for controls, including integration of the two plants. The specific controls integration requirements have not been evaluated at this time as the currently completed study is only feasibility-level. HYDROLOGY o 2021 Hydrology Report has a South Fork Flow Discharge Curve and hydrology based on Russell Creek. That is correct. P OLARCONSULT M EMORANDUM Page 3 of 3  Is there a flow discharge curve and hydrology for the potential inlet site (combined North & South Forks)? No, there is no gaging station established at that location. The hydrology model developed based on the south fork gauging station record is the best currently-available hydrology model for analysis of projects in the Unga Man basin. This is because (1) the south fork gaging station has the most complete available period of record in the Unga Man Creek basin (3.5 years of data in a 4.5 year period of record) and (2) year-round hydrology is well- represented in the available data at this station. Both the north fork and bridge gauging stations are significantly inferior candidates for record extension, with the north fork having 30% less data (2.5 years) and bridge site having 20% less (2.75 years). Both of these stations also have portions of the year (mid-summer) with only a single year of data in their periods of record, makes them inferior candidates for record extension. Accordingly, the incremental effort to develop hydrology models based on the other two gaging stations would not significantly increase overall confidence in the feasibility analysis findings. This judgment is rendered with recognition of other uncertainties in the feasibility-level analysis such as market for power, permit terms and conditions, actual construction cost, etc. The south fork extended record hydrology was applied to the RM 1.4 diversion site by scaling south fork flows by the ratio of respective basin areas (2.59 mi2 / 1.19 mi2 = 2.17 multiplier) to estimate intake site hydrology.  With the assumed in-stream flow requirement what would be the resultant inlet flows? Resultant inlet flows would be unchanged at up to 18 cfs as available, but this full design flow would be available less often. The impacts of a presumed 2 or 5 cfs ISFR imposed at the intake on project performance are summarized in the following table. Hydro Plant Performance Parameter No ISFR 2 cfs ISFR 5 cfs ISFR Resource capacity factor 75% 70% 63% Percentage of Utility Load Met by Hydro 83% 81% 78% Gross excess hydro kWhs available for dispatched energy services 436,000 418,000 388,000 Resource capacity factor: Actual water available to the project divided by design flow on an annualized basis.