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 (i) Repair or replace supports, hangers, guides, expansion joints, and
auxiliary equipment as required.
( j ) Stop water leaks in the floor and walls of tunnels and conduits
( r e f e r to paragraph 3.3(a)).
( k ) Use clean, uniform backfill for pipe trenches of underground
systems. D o not use frozen fill, sod, cinders, or large stones. Backfill the
trench simultaneously on both sides of the conduit to prevent unequal or
unbalanced side pressures. B a c k f i l l in layers 6-inches thick up to 6 inches
above top of conduit. P r o t e c t traffic crossings with timbers until the fill
settles.
3.2 Maintenance of Cathodic Protection Systems. General maintenance
procedures for cathodic protection systems are found in NAVFAC MO-306,
Maintenance and Operation of Cathodic Protection Systems and MO-307, "Cathodic
Protection Systems Maintenance. Make repairs or replacements as required
a f t e r periodic inspections. R e f e r to manufacturer's instructions for
i n f o r m a t i o n on maintaining specific installations and equipment.
3.3 Maintenance of Manholes. Make repairs as recorded during
periodic inspections of maintenance program.
( a ) Water leaks. S t o p water leaks in the floor and walls. For concrete
manholes, proceed as follows:
(1) Chip out the porous area using a cold chisel and a hammer.
This will expose sound concrete facilitating patch bonding.
(2) Plug holes or cracks with a quick setting cement mortar or with
a putty made of calcium chloride and water.
( 3 ) If water enters through the manhole floor, first clean the
f l o o r , removing accumulated silt. I f the floor is generally sound, except for
t h e joints at the wall or isolated cracks, proceed as indicated in (1) and (2)
above. If the concrete of the floor shows general porosity, pour a new floor.
( b ) Repair ladders as required.
( c ) Repair electrical installation and fixtures if necessary,
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