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(A)
Scope
The manhole
base liner shall be a FIBERGLASS REINFORCED PLASTIC (F.R.P.) BASE
LINER SYSTEM, which is resistant to the chemical environment normally
found in wastewater transmission systems. The F.R.P. Base Liner
shall be a non-load bearing component integrally cast and adequately
anchored inside new precast concrete manhole base sections during
concrete casting process at the concrete precaster's manufacturing
facility
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(B)
FIBERGLASS MANHOLE BASE LINER
(1) The prefabricated F.R.P. base liner shall be a one piece construction
of unlayered, homogenous composite. Minimum thickness shall be
.12" - .20" (3 mm - 5 mm) and shall be in lengths and
nominal inside diameters corresponding to the precast concrete
base section.
(2) The prefabricated F.R.P. manhole base liner shall include
full flow channels with side walls to the crown of the pipe; inner
surface of the bench to have an anti-skid pattern; watertight
gasketed pipe bell connections or F.R.P. / PVC boot hole sleeves
to suit specific pipe types, grade and alignment, shall be monolithically
attached to prefabricated F.R.P. base liners to extend to the
outside profile of the precast concrete structure per drawing
details.
(3) The outer surface of the liner to be aggregate coated and
have steel spirals/ lattice bonded to the F.R.P. to insure adequate
anchoring to concrete base sections to pass vacuum test with 10"
of negative pressure.
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(C)
INSTALLATION IN PRECAST CONCRETE
(1) The F.R.P.
base liner shall be cast integral with the precast concrete manhole
base section in accordance with the liner manufacturer's specifications.
The liner must be fully supported during the casting process;
lifting devices shall not penetrate inside walls F.R.P. base liner.
(2) Inside F.R.P. liner surfaces shall be free of bulges, dents
and other defects that result in a variation of inside diameter
of more than 1/4" (7 mm) for base liner flow channel and pipe
connections. The precast concrete pipe penetration joint surfaces
shall be free of excess concrete at external and internal surfaces
to insure proper seal of pipe connection and F.R.P. liner.
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(D)
FIELD ASSEMBLY AND INSPECTION PRECAST CONCRETE MANHOLE WITH F.R.P.
LINER
(1)
During the field installation of F.R.P. lined precast manhole
base sections; all pipe connections are to be sealed per the liner
manufacturer's standard method and details. Precast concrete sections
shall be sealed as prescribed by precast manufacturer and utility
specifications.
(2) The interior surfaces of the liner shall be completely free
from pinholes, cracks, pits or defects that are detrimental to
the intended use of the F.R.P. base liner. No F.R.P. base liner
shall have holes, or openings, which will permit the passage of
liquid or gases through the liner wall to precast concrete. There
shall be no exposed concrete mortar through inside liner surface
to include (but not limited to) pipe penetrations. All mechanical
anchor attachments through liner surfaces must be sealed with
an approved elastomeric sealant. Consult liner manufacturer for
specific information regarding approved sealant supplier list
and availability.
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