2. Check for excessive wear of moving parts,
3. Flush and back blow the sludge withdrawal line
by using high-pressure water or compressed air.
Do not allow the waterline to be cross con-
nected to the drinking water supply system.
4. Check the plows or rakes and straighten them if
5. Check the motor condition, couplings, and
service shear pins.
6. Clean equipment and paint as necessary.
When the equipment has an overload alarm, check
it for operation. If the alarm sounds at any time, shut
off the equipment, locate the source of trouble, and
correct it. Under no condition should the alarm switch
be nullified to provide continuous operation. If the
overload is caused by a sludge buildup leading to
cutout of the starter switch or pin shearing, the tank
must then be drained and the sludge flushed out.
As with the revolving-sludge collectors, specific
maintenance procedures in conveyor-type collector
basins are in the manufacturers instructions.
Maintenance procedures on the tanks and structures
are the same for this type of sedimentation basin as
they are for the circular-type basin. Generally, the
maintenance procedures for gears, chains, sprockets,
reducers, and so on, are also the same as those for
Where stubborn water problems exist in water
supplies, the sedimentation tank equipment may be
protected by cathodic protection. Cathodic protection
is a method of protecting metal surfaces from
corrosion through the use of a direct-current voltage.
The voltage is applied so that the current tends to flow
from the direct-current source through the soil or water
to the metal surface to be protected. This flow of
current applies electrical energy that reverses the
natural process of corrosion.
There are two well-known methods of cathodic
the impressed current system and the
galvanic anode system. The impressed current system
requires graphite rods and an external power source to
establish enough voltage. The galvanic anode system,
which requires no external power supply, uses metallic
anodes, such as magnesium, zinc, or aluminum.
Cathodic protection systems may be maintained
by activity personnel or by service contract. The field
engineering officer will provide guidance in
developing maintenance procedures or in contracting
for such services.
IMPRESSED CURRENT SYSTEM.Make
inspections and necessary maintenance repairs at
monthly intervals. The steps for the inspection include
1. Check exterior of enclosure for rust, corrosion,
or mechanical damage; check hinges and locks for
inadequate lubrication, rust, or other deficiencies;
check wiring and fastenings and rectifier for broken or
damaged insulation, and for rust or corrosion on
conduit; and, check exposed wires and cables and all
electrical connections for insecurity, frayed or broken
insulation, and other deficiencies.
2. Check interior of enclosure for rust, moisture
condensation, loose wiring, and signs of excessive
heating. (Do not put hand tools inside the enclosure.)
3. Check anode suspensions for rust, corrosion,
bent or broken suspension members, frayed or broken
suspension lines or cables, loose bolts, loose cable
connections, and frayed or broken wiring.
4. Whenever necessary, replace or repair any item
which will not pass inspection for continued service,
and paint switch cans and exposed rectifier housing and
other electrical gear as necessary.
GALVANIC ANODE SYSTEM.The only
maintenance required for a galvanic anode system or a
sacrificial anode system is monthly inspection and
potential tests to determine when replacement of
anodes is necessary and to ensure continuity of the
electric circuit. The procedures that apply are as
1. When an abnormal decrease in current output
(or potential of the protected structure) occurs, the