Wheeler Bottom Underdrains are very similar to the Bell Bottom Underdrains.  However, the cone is 10" X 10" instead of 8" X 8".  The Wheeler bottom is essentially series of inverted pyramids. Each pyramid then is fitted with a series of ceramic spheres placed in the pyramid. These ceramic balls are generally 3" in diameter supported by 1" diameter ball.  A layer of graded gravel is placed on top of the ceramic balls to support the filtration media above and also to distribute backwash water.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Again, care should be taken not to damage the ceramic balls by evacuating them through a vacuum truck.

 

Wheeler Bottom Underdrains will always have gravel support.  The design usually consists of:

 

- 1 1/2" X 3/4"

- 3/4" X 1/2"

- 1/2" X 1/4"

- 1/4" X 1/8"

- 1/8" X #16

- Sand

- Anthracite