LAR 512 – Fall 2002

 

PROBLEM #6 – BASICS OF POROUS MEDIA

 

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http://www.usga.org/green/coned/greens/recommendations.html

 

Using the above website, answer the following questions:

 

  1. Which of the following soils meet the USGA root mix standards for green construction (Table 3)?  __________

 

Soil A              Soil B              Soil C              Soil D

 

Fine gravel                      3%                   2%                   2%                   0%    

Very coarse sand            2%                   9%                   3%                   6%

Coarse sand                 32%                 32%                 42%                 23%    

Medium sand                40%                 27%                 45%                 27%                

Fine sand                      23%                 12%                   8%                 19% 

Very fine sand                0%                 14%                   0%                   5%

Silt                                 0%                   2%                   0%                   8%

Clay                               0%                   2%                   0%                 12%

 

  1. Calculate the bridging factor, permeability factor, and uniformity factors for the following root zone mix and gravel base when an intermediate layer is not used (Table 2):

 
 
Coarse gravel
Medium gravel
Fine gravel
Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand		 Size Range
 
20 to 76 mm
5 to 20 mm
1 to 2 mm
0.5 to 1 mm
0.25 to 0.5 mm
0.1 to 0.25 mm
0.05 to 0.1 mm		 Median Size
 
48 mm
12.5 mm
3.5 mm
1.5 mm
0.75 mm
0.375 mm
0.175 mm
0.075 mm		 Root Mix
 
0%
0%
0%
2%
20%
60%
18%
0%		 Gravel Layer
 
5%
45%
50%

 

What is the bridging factor for the above two materials?  D15 (gravel) less than or equal to 5 X D85 (root zone) = __________

 

What is the permeability factor for the above two materials?  D15 (gravel) greater than or equal to 5 X D15 (root zone) = __________

 

What is the 1st uniformity factor for the above two materials?  D90 (gravel) / D15 (gravel) is less than or equal to 2.5 = __________

 

What is the 2nd uniformity factor for the above two materials?  No particles greater than 12 mm __________

 

What is the 3rd uniformity factor for the above two materials?  Not more than 10% less than 2 mm __________

 

What is the 4th uniformity factor for the above two materials?  Not more than 5% less than 1 mm = __________

 

  1. Discuss whether the above root zone mix and gravel layer will or will not meet the standards?

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4.   Describe what will happen when the root zone mix is installed over top of the gravel layer? 

 

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