6.3. ERMUSR 10-09-2007 - Laserfiche WebLink

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3.0 Assessment of Generation Capability The United States Geological Study (USGS) has maintained a stream flow gaging station on the Elk River near Big Lake, Minnesota. The station number is 0527500. Information from this gage location has been collected since 1911. The drainage area at the gaging station is 615.00 square miles. The drainage area at Lake Orono is reported to be 640 square miles. An evaluation of potential generation was completed based on several different capacity generating units. Table 2-1 presents the installed capacity and potential generation without adjustments for availability. The availability factor represents an assumption regarding the overall availability of the site when considering low flow, maintenance, and other possible plant shutdown periods. An assumed availability factor of 0.8 has been applied to the yearly generation to determine the adjusted yearly generation. The analysis was completed based on average daily discharge, adjusted for the difference in drainage area between the gaging station and the dam, and limits based on capacity of the generating unit(s). Once stream flow exceeded the generating capacity, water would be spilled through the tainter gates or over the spillway while maintaining the maximum generation capacity. Copies of the excel spreadsheets that were used to evaluate the potential generation are included as Appendix 3-1. Table 3-1 Summary of Generation Generator Capacity (KW) Yearly Generation (KW-hr) Adjusted Yearly Generation (i(11V-hr) 180 1,491, 000 1,193, 000 200 1, 619, 000 1, 295, 000 300 2,011,000 1,609,000 400 2,265,000 1,812,000 All 2,588,000 2,070,000 Using the value of power ($0.04/KW-hr), the value of the average annual generation varies from about $50,000 to $95,000 depending upon the installed capacity and site availability. P:\Mpls\23 MN\71\2371089 Elk River Municipal-Orono Dam\WorkFileslReport\Lake Orono Dam Assessment Report.doc 4