77 Ill. Adm. Code 930.40
Treatment Plant Maintenance
Section 930.40Â Treatment
Plant Maintenance
a)Â Â Â Â Â Â Â Â Slow sand filtration treatment plants shall be maintained as
follows:
1)        Cleaning. Whenever the design flow can no longer be achieved
the filter must be cleaned. In order to clean the filter, the water level must
be lowered to 2 to 3 inches below the top of the sand. The filter must not be
drained. The accumulated mud and slime along with ½ inch of the top of the
sand surface must be removed.
2)Â Â Â Â Â Â Â Â Proper
Filter Depth. After 6 inches of sand has been removed due to repeated
cleaning, additional sand which shall comply with the design criteria specified
in Section 930.20(c) must be added so the filter is restored to the original
depth of 3 feet.
b)Â Â Â Â Â Â Â Â Cartridge filtration
treatment plants shall be maintained as follows:
1)Â Â Â Â Â Â Â Â Cartridge
filters shall be cleaned or replaced according to the manufacturer’s
recommendation.
2)Â Â Â Â Â Â Â Â Replacement
cartridges shall be equal to the original equipment.
c)Â Â Â Â Â Â Â Â Ultraviolet
disinfection equipment shall be maintained as follows:
1)Â Â Â Â Â Â Â Â The
ultraviolet equipment lamp shall be cleaned or replaced when the equipment has
a lamp intensity failure. The lamp shall be replaced when the equipment has a
lamp failure.
2)Â Â Â Â Â Â Â Â The
ultraviolet lamp shall be replaced at intervals specified by the manufacturer,
but no less often than annually.
3)Â Â Â Â Â Â Â Â Replacement
ultraviolet equipment lamps shall be equal to the original equipment.