Terms for BBackfill material
Biological cleaning stage
Biological oxygen demand (BOD5)
For correct installation of a plastic tank, gravel (usually maximum grain size 8.16) is recommended. It is very easy to work with and, in contrast to chippings and sand, does not form cavities. In addition, gravel has a high self-supporting force and can therefore be installed loosely, i. e. without additional compaction.