Measures to Minimize Involuntary Spill Clause Samples

Measures to Minimize Involuntary Spill. Chelan PUD has implemented operational improvements that reduce involuntary spill, both during the fish migration season (April-August) and during the rest of the year, when the TDG numeric criterion is 110%. The track record for TDG abatement by reducing spill through operational measures at the Project has shown continuous improvement over the past five years. In response to requests from Ecology, Chelan PUD has prepared summaries of the incidence of spill since 1995 (Table 2-9 and Table 2-10). Flows prior to 1995 are not included because operations of upstream storage projects were modified by the FCRPS 1995 Biological Opinion. These tables show that flows arriving at the Project will rarely exceed the hydraulic capacity of the powerhouse during the September-March period. Also, even low levels of spill will cause exceedance of the 110% criterion. Thus, avoidance of spill during this time of year is the most viable means to comply with the water quality standards. During the April-August fish migration season, the Project can comply with 120/115% criteria up to the level of the 7Q10 flow. Spill has been very infrequent, since 2000, during the September to March period, when the TDG criterion is 110%. Also, the hourly project discharge has rarely exceeded the hydraulic capacity of the powerhouse since 2000. Hourly total project discharge and spill volumes are shown by month in Appendix E. Three factors have contributed to the reduction in spill and spikes in hourly discharge during these months. Spill Level (flow) (Flow-201kcfs) % TDG April % of hours May % of hours June % of hours July % of hours August % of hours <=10 kcfs (201-211 kcfs) 112.86 1.91 2.76 4.06 3.36 0.21 10 - 20 kcfs (211 - 221 kcfs) 114.21 1.60 2.05 3.72 2.99 0.19 20 - 30 kcfs (221 - 231 kcfs) 115.57 1.28 2.11 2.65 1.49 0.03 30 - 40 kcfs (231 2341 kcfs) 116.92 0.94 1.75 2.36 0.79 0.01 40 - 50 kcfs (241 - 251 kcfs) 118.28 0.66 2.18 2.62 0.43 0.00 > 50 kcfs (>251 kcfs) NA 0.62 5.97 12.47 0.48 0.01 Total Spill Frequency 7.02 16.82 27.89 9.54 0.46 TDG is for edge of aerated zone (non-fish spill compliance zone) TDG estimated from spill regression (TDG = 0.1509 x + 111.61) at the FOP1 site Table 2-10: Rocky Reach Projected TDG for Flows above Maximum Turbine Flow for Months Outside of the Fish Passage Season (1995 – 2003) Spill Level (Flow-201kcfs) % TDG September % of hours October % of hours November % of hours December % of hours January % of hours February % of hours March % of hours <= ...