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stone_outlet_protection [2022/05/06 11:43] adminstone_outlet_protection [2025/09/30 15:18] (current) admin
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-====== Stone Outlet Protection ======+====== Stone Outlet Protection (Riprap) ======
  
-Stone outlet protection is designed to release water from management practices at non-erosive velocities.  An apron of angular stone is placed at the outlet to prevent erosion by dissipating the energy of water as it flows over.+Stone outlet protection, or riprap, is designed to release water from management practices at non-erosive velocities.  An apron of angular stone is placed at the outlet to prevent erosion by dissipating the energy of water as it flows over.
  
 **Advantages** **Advantages**
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 ===Maximum Velocities for Various D<sub>50</sub> Sizes and Shapes=== ===Maximum Velocities for Various D<sub>50</sub> Sizes and Shapes===
-|=Maximum Velocity (ft/sec)|=D<sub>50</sub> Cubical (in)|=D<sub>50</sub> Spherical (in)| + 
-|10.8|12|14| +^  Maximum Velocity (ft/sec)  ^  D<sub>50</sub> Cubical (in)  ^  D<sub>50</sub> Spherical (in)  ^ 
-|9.9|10|12| + 10.8   12   14  
-|8.8|8|10| + 9.9   10   12  
-|7.6|6|8| + 8.8     10  
-|6.3|4|6| + 7.6      
-|5.0|2|4|+ 6.3      
 + 5.0      |
  
 A geotextile fabric barrier should be installed underneath the stone to prevent the stone from settling and to prevent erosion of the outlet structure.  Care should be taken during construction to ensure that the fabric is not torn, cut, or punctured.  Any damage should be repaired before proceeding with construction. A geotextile fabric barrier should be installed underneath the stone to prevent the stone from settling and to prevent erosion of the outlet structure.  Care should be taken during construction to ensure that the fabric is not torn, cut, or punctured.  Any damage should be repaired before proceeding with construction.
  
 ===Recommended Stone Gradation=== ===Recommended Stone Gradation===
-|=Percent Passing by Weight|=Diameter (in)| + 
-|100|2 x D<sub>50</sub>+^  Percent Passing by Weight  ^  Diameter (in)  ^ 
-|60-85|1.5 x D<sub>50</sub>+ 100   2 x D<sub>50</sub>  
-|25-50|D<sub>50</sub>+ 60-85   1.5 x D<sub>50</sub>  
-|5-20|0.5 x D<sub>50</sub>+ 25-50   D<sub>50</sub>  
-|0-5|0.2 x D<sub>50</sub>|+ 5-20   0.5 x D<sub>50</sub>  
 + 0-5   0.2 x D<sub>50</sub>  | 
 + 
 +[{{ :wiki:images:correct_riprap.jpeg?direct&600 |Correctly installed riprap at pipe outlet}}] 
 + 
 +[{{ :wiki:images:poorly_installed_riprap.jpeg?direct&600 |Erosion around riprap from improper shaping}}]
  
 =====Construction===== =====Construction=====
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   *The apron must be at least 1.5 feet below the invert elevation of the outlet structure   *The apron must be at least 1.5 feet below the invert elevation of the outlet structure
  
-====Manning's "n" Values for Various Rock Sizes==== +**Stone Outlet Protection to a Flat Area (Left) and Well-Defined Channel (Right)** 
-|=Diameter (in)|="n" Value| +{{ :wiki:images:stone_outlet_protection.png?600 |}}
-|2|0.030| +
-|4|0.033| +
-|6|0.036| +
-|8|0.037| +
-|10|0.039| +
-|12|0.040| +
- +
- +
-====Stone Outlet Protection to a Flat Area (Left) and Well-Defined Channel (Right) +
-[[File:/Images/Stone_Outlet_Protection.PNG|Source: Adapted from the Georgia Stormwater Manual]]+
  
 =====Maintenance===== =====Maintenance=====
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 ===References=== ===References===
-  *[[https://www.nrcs.usda.gov/wps/portal/nrcs/detail/wy/technical/engineering/?cid=nrcs142p2_027269|NRCS Rock Outlet Protection Fact Sheet]]+  *[[https://efotg.sc.egov.usda.gov/api/CPSFile/31113/468_WI_CPS_Lined_Waterway_or_Outlet_2021|NRCS Conservation Practice Standard 468 - Lined Waterway or Outlet]]
stone_outlet_protection.1651851818.txt.gz · Last modified: by admin

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