2010-01-20_REVISION - C1981008 (5)

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Marcia Talvitie January 20, 2010 Page 2 . Further, numerous inconsistencies were identified with the new Pond 012 design information that was submitted with PR-6. The SEDCAD demonstrations for the 1 OYr and 25 Yr designs show fatal flaws in that the spillway elevations and dam height do not match the approved Pond 012 As-Built (Map 2.05.3(3)-12-4). For example, the top of the dam on the revised SEDCAD runs is 5610' and the top of embankment is 5613" on the As-Built. The top of riser is 5611' on the As-Built (which would place the invert of the spillway one foot above the top of dam as proposed with PR-6. In the new revised pond description (see page 2.05.3(3)-12-4) the Emergency Spillway is shown at an elevation of 5609'which also is not consistent with other information. There are no Emergency Spillway elevations shown in the new SEDCAD demonstrations for either the 10Yr or 25 Yr events. This information is required for the 25Yr-event to show that the pond meets the requirements of 4.05.9 (7) (d). Much of the information presented for the Pond 012 re-design appears to be inconsistent and it is unclear what the revised SEDCAD runs are attempting to demonstrate. If WFC is proposing to change the spillway configurations then this should be clearly explained and the SEDCAD demonstrations need to reflect accurate information. A new As-Built Certification would be required if the pond configuration or spillway elevations are changed. Please clearly explain why Pond 012 is being re-designed and clarify the discrepancies noted in the revised SEDCAD demonstrations as described above. 4. Pond 013 is also being re-designed because it will receive increased drainage due to WFC's decision to eliminated Pond 010. With this revised design WFC demonstrates that the as builtpond-is-sufficient-to handle-the-revised-drainage-area. Spill-way elevations-remain-the same and the pond configuration is not changing therefore WFC did not resubmit the As- Built Certification map but did submit a revised Engineering and Hydrologic Design and As Built SEDCAD and SurvCad hydrology calculations. Only one minor inconsistency was identified on the existing approved As-Built. The emergency spillway elevation is incorrectly labeled on Map 2.05.3(3)-18 as 5657' and should be 5557'. Please check this elevation and make the necessary correction to Map 2.053(3) -18. 5. On page 2.05.3(3)-6-34 of the original Pond 013 Design Calculations, permit text regarding manual operation of the pond was taken out of the permit document with PR-6. This appears to be the case for the Pond 011 Design Calculations as well. This language was a permit condition that was placed on the permit application package with the last Midterm Review and more recently with TR-56. Please reincorporate this language (see strike out on page 2.05.3(3)-6-34) into the Engineering and Hydrologic Designs for Ponds 011 and 013. Otherwise provide a detailed explanation why this permit language should be removed from the permit document. 6. Pond 015 is a new pond design submitted with PR-6. This pond is designed to capture and contain without discharge the 100-year24-hour precipitation event. The operator has successfully demonstrated that the temporary impoundment will safely control the design precipitation event. However, the operator has not demonstrated how the water will be