Scheduling of Maintenance to Avoid High Flow Periods Sample Clauses

Scheduling of Maintenance to Avoid High Flow Periods. Chelan PUD began an aggressive program in 2000 to limit the incidence of spill due to maintenance outages during periods of the year and times of day when river flows approach the hydraulic capacity of the powerhouse. The hydraulic capacity of the powerhouse, when all 11 turbines are operating, is 204,000 cfs at the most efficient operating point and 212,000 cfs can be passed without needing to spill. Typically, these flow levels are not reached during river management for power generation. The hydraulic capacity of the powerhouse, when 10 turbines are available, is reduced to either 182,000 cfs or 187,000 cfs, depending on the type of turbine out of service for maintenance. The planning process schedules lengthy maintenance outages to the months in the year when flow releases from Grand Coulee and power demand are typically the lowest, with most turbine overhaul scheduled for March to mid-May or September to mid- November. Short duration outages, such as inspections, trash rack cleaning and smaller repair jobs are either scheduled for nighttime and weekends or, if scheduled during the day, are of a nature that work can be suspended or postponed to avoid spill if river flows approach the hydraulic capacity. Outage planning is focused on the shape of the daily flow pattern. The use of the Hourly Coordination Agreement gives the project operations personnel sufficient advance warning to cancel planned outages and avoid spill if the flow pattern changes to higher levels than predicted.