Bell Bottom Underdrains are a very old design. These underdrains consist of a glass Bell which fits over a 1/2" copper tube, inset into a 8" X 8" cone, similar to a wheeler style underdrain. These glass Bells were made in a pre-fabricated mold by the Viking Glass Company in West Virgina.
Bell Bottoms will all have gravel support consisting of the following rock sizes:
- 2 1/2" X 1 1/2"
- 1" X 1/2"
- 1/2" X 1/4"
- 1/4" X 1/8"
- 1/8" X #16
During the filtration media removal process, care should be taken not to evacuate the bells with a vacuum truck. This will cause damage to the Bells through breakage, as the glass edges are brittle. Also, during the large rock installation, care of rock placement should be recognized. Dropping the rock on the glass Bell could damage or break it.