ML042080437
| ML042080437 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf, PROJ0720  |
| Issue date: | 07/09/2004 |
| From: | Fitzgerald R US Dept of the Army, Corps of Engineers |
| To: | Bagchi G Division of Engineering |
| ANAND R NRR/DRIP/RNRP, 415-1146 | |
| References | |
| FOIA/PA-2005-0280 | |
| Download: ML042080437 (2) | |
Text
DEPARTMENT OF THE ARMY VICKSBURG DISTRICT, CORPS OF ENGINEERS 4155 CLAY STREET VICKSBURG, MISSISSIPPI 39183-3435 REPLY TO ATTENTION OF:
hffp://www.mvk.usace.army.mil/
July 9, 2004 Engineering Division Hydraulics Mr. Goutam Bagchi U.S. Nuclear Regulatory Commission Mail Stop: 0-9 E3 NRR Washington, DC 20555-0001
Dear Mr. Bagchi:
I refer to your July 1, 2004 meeting in our office with representatives of the U.S. Army Corps of Engineers and Pacific Northwest National Laboratories concerning the Grand Gulf Nuclear Power Plant.
The: following information is provided as a summary of the method utilized in determining the project design flood on the Lower Mississippi River.
- Major storms that have occurred in the central United States were examined for their flood-producing potentialities on the Lower Mississippi River.
- Selected storms were transposed or shifted in timing within the season they occurred and arranged in critical sequence on. the drainage area to produce maximum flows on the Lower Mississippi River.
- Observed hydrographs and hydrographs computed from unit graphs were used to determine flows from major tributaries.
- The resulting flows were routed to key stations along the river, unregulated and regulated by tributary reservoirs, and the project design flood was selected from these routed flows.
- Of the selected storms, four combinations were used for detailed study on the basis of the large floods produced and the variation in season of occurrence.
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- The combination designated as 58A was selected as the Project Design Flood for the Lower Mississippi River.
- Combination 58A (winter season) consists of the 6-24 January 1937 storm over all areas with rainfall excess increased 10 percent, followed in 4 days by the 3-16 January 1950 storm over all areas above Cairo, and followed in 3 days by the 4-18 February 1938 storm transposed 90 miles and rotated 20 degrees for all areas below Cairo.
The levee on the west bank opposite the Grand Gulf Nuclear Power Plant (approximately levee station 5300 + 00) varies in elevation from 105.0 ft National Geodetic Vertical Datum (NGVD) to 102.0 ft NGVD. The levee is proposed to be raised 3 to 4 ft. within the next 7 to 10 years in that location.
The project design flood elevation at river mile 406, the location of the Grand Gulf Nuclear Power Plant, is 102.2 ft NGVD based on the Refined 1973 MR&T Project Flood Flowline.
Should you have questions concerning the information provided, please contact Mr. Rick Robertson (Chief, Hydraulics Section) at 601-631-5688.
Sincerely, Robert H. Fitzgerald, P.E.
Chief, Engineering Division