MIn eight feet deep, pref. 10. Floor plan 4'X 5'
Drain hole in one corner, floor to slope to drain and water trap with macerator.
Internal surfaces to be painted out in black bituminous paint.
Shackles at 3" above floor at two foot intervals around pit. Further rows of shackles at 3, 4, 5, 6, 7, and 8 foot above floor level.
Shackles to be rawlbolted or similar.
A rubber brick of the type used as a training aid in swimming pools should be provided.
Adequate ventilation must be maintained at all times.