PURPOSE: To reduce redundant restrictive language.
Table 4.
Table 1-Design Factors of Safety for Slope Stability Earth and Rock Conventional Dams
Loading Condition | Factor of Safety |
End of construction, full reservoir* | 1.4 |
Steady seepage, full reservoir* | 1.5 |
Steady seepage, maximum reservoir** | 1.3 |
Sudden draw down, from full to empty reservoir (if applicable) | 1.2 |
Earthquake***, steady seepage, full reservoir* | 1.0 |
*Full reservoir means water level is at the water storage elevation.
**Maximum reservoir means water level is at maximum water level attained during the spillway design flood or at the dam crest elevation, whichever is lower.
***Earthquake loading will vary according to dam location in relation to seismic source zones and downstream environmental zones.
(See Table 4).
Table 2-Design Factors of Safety Concrete Conventional Dams
Failure Mode | Loading Condition | Factor of Safety |
Overturning | full reservoir* | 1.5 |
maximum reservoir** | 1.3 | |
Sliding | full reservoir* | 1.5 |
maximum reservoir** | 1.3 | |
Structural integrity | full reservoir* | 1.5 |
maximum reservoir** | 1.3 | |
Earthquake*** any mode | full or maximum reservoir* & ** | 1.0 |
*Full reservoir means water level is at the water storage elevation.
**Maximum reservoir means water level is at maximum level attained during the spillway design flood.
***Earthquake loading will vary according to dam location in relation to seismic source zones and downstream environmental zones.
(See Table 4).
Table 3-Design Factors of Safety for Slope Stability Industrial Water Retention Dams
Loading Condition | Factor of Safety |
Starter dam, end of construction, full reservoir* | 1.4 |
Any other stage of construction, full reservoir*, steady seepage | 1.3 |
Any other stage of construction, maximum reservoir*, steady seepage | 1.0 |
Completed dam, full reservoir*, steady seepage | 1.5 |
Completed dam, maximum reservoir**, steady seepage | 1.3 |
Earthquake***, steady seepage, full reservoir* | 1.0 |
*Full reservoir means water level is at the water storage elevation.
**Maximum reservoir means water level is at the maximum level attained during the spillway design flood or at the dam crest elevation, whichever is lower.
***Earthquake loading will vary according to dam location in relation to seismic source zones and downstream environmental zones.
(See Table 4).
Table 4-Required Design Acceleration For Earthquake Design
Dam Type | Stage of Construction | Special Descriptions | I | Environmental Class II III | |
Conventional | New dams less than 50 feet | ||||
or Industrial | Completed | in height | .75PMA* | .5PMA* | .25PMA* |
New dams greater than | |||||
50 feet in height** | .75PMA* | .5PMA* | .4PMA* | ||
Industrial | Starter dam | New dams** | .5PMA* | .2PMA* | .1PMA* |
After starter dam is | |||||
finished and before final | |||||
dam is completed | New dams** | .75PMA* | .5PMA* | .2PMA* |
Zone | PMA* | Intensity** |
A | 0.31 g | IX-X |
B | 0.28 g | IX |
C | 0.26 g | VIII-IX |
D | 0.23 g | VIII |
E | 0.20 g | VII-VIII |
F | 0.17 g | VII |
ZONE A ZONE B | ZONE C | ZONE D | ZONE E | ZONE E (cont.) | ZONE F |
Dunklin Bollinger | Carter | Crawford | Audrain | Lewis | Adair |
Mississippi Butler | Howell | Dent | Barry | Lincoln | Andrew |
New Madrid Cape Girardeau | Iron | Douglas | Barton | Linn | Atchison |
Pemiscot Ripley | Madison | Franklin | Bates | Livingston | Buchanan |
Scott | Oregon | Jefferson | Benton | McDonald | Clay |
Stoddard | Perry | Ozark | Boone | Macon | Clinton |
Wayne | Reynolds | Phelps | Caldwell | Maries | Davis |
St. Francois | Pulaski | Callaway | Marion | Dekalb | |
Ste. Genevieve | St. Louis | Camden | Miller | Gentry | |
Shannon | St. Louis City | Carroll | Moniteau | Grundy | |
Taney | Cass | Monroe | Harrison | ||
Texas | Cedar | Montgomery | Holt | ||
Washington | Chariton | Morgan | Mercer | ||
Wright | Christian | Newton | Nodaway | ||
Clark | Osage | Platte | |||
Cole | Pettis | Putnam | |||
Cooper | Pike | Schuyler | |||
Dade | Polk | Sullivan | |||
Dallas | Ralls | Worth | |||
Gasconade | Randolph | ||||
Greene | Ray | ||||
Henry | St. Charles | ||||
Hickory | St. Clair | ||||
Howard | Saline | ||||
Jackson | Scotland | ||||
Jasper | Shelby | ||||
Johnson | Stone | ||||
Knox | Vernon | ||||
Laclede | Warren | ||||
Lafayette | Webster | ||||
Lawrence |
* PMA is Probable Maximum Acceleration of bedrock which is determined as a fraction of the acceleration of gravity (g = 32.2 fps2) for the six zones in Missouri (see 10 CSR 22-1.020(41)).
** See 10 CSR 22-2.020(3) for clarification.
*** Modified Mercalli Intensity.
Table 5-Spillway Design Flood Precipitation Values
Environmental Class | |||||
Dam Type | Stage of Construction | Special Descriptions | I | II | III |
Conventional or Industrial | Completed | Any existing dam** | .75PMP* | .5PMP* | 100 Yr.**** |
New dam less than 50 feet in height*** | .75PMP* | .5PMP* | 100 Yr.**** | ||
New dam greater than 50 feet in height | .75PMP* | .5PMP* | 100 Yr.**** | ||
Industrial | Starter dam | Any | .5PMP* | .2PMP* | .1PMP* |
After starter dam is finished and before final dam is completed | Any | .75PMP* | .5PMP* | .2PMP* |
*PMP is Probable Maximum Precipitation.
**Existing dam means a dam which was completed by August 13, 1981 or which was started prior to August 13, 1981 and completed by August 13, 1987.
***See 10 CSR 22-2.020(3) for clarification.
****100 Yr. is the 100 year frequency rainfall event.
10 CSR 22-3.020
*Original authority: 236.400, RSMo 1979; 236.405, RSMo 1979, amended 1993, 1995; 236.415 RSMo 1979, amended 1995; 236.435, RSMo 1979; 236.440, RSMo 1979; and 236.465, RSMo 1979.