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(A)
Scope
The manhole
liner shall be a FIBERGLASS REINFORCED PLASTIC (F.R.P.) LINER SYSTEM,
which is resistant to the chemical environment normally found in
wastewater transmission systems. The F.R.P. Liner shall be a non-load
bearing component integrally cast and adequately anchored inside
new precast concrete manhole 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. liner shall be
a one piece construction of unlayered, homogenous composite with
minimum thickness shall be .12" - .20" (3 mm- 5 mm) and
shall be in lengths and nominal inside diameters corresponding to
the precast concrete manhole 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 and F.R.P. hole sleeves to suit specific pipe types,
grade and alignment, shall be monolithically attached to prefabricated
F.R.P. base manhole 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 anchoring
to concrete sections.
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(C)
INSTALLATION IN PRECAST CONCRETE
(1) The F.R.P.
liner shall be cast integral with the precast concrete manhole
base, riser and flat top/ cone sections in accordance with the
liner manufacturer's specifications. The liner sections including
the base liner (benching and pipe bell connections & channels
greater than 12" diameter) must be fully supported during the
casting process, lifting devices shall not penetrate F.R.P. 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 section 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)Prefabricated
F.R.P. brick adjustment collar or GU F.R.P. Convertible Collar
liner for masonry grade adjustment shall extend vertically to
cast iron cover ring.
(2) During
the field installation of F.R.P. lined precast manhole sections,
all internal seams are to be sealed per the liner manufacturer's
standard method and details, to include the use of approved butyl
sealant strips (ASTM C-990 Section 6.2) at internal liner joint
flange. Outer joints of precast concrete sections shall be sealed
as prescribed by precast manufacturer and utility specifications.
(3) After structure assembly is complete, the interior surfaces
of the liner shall be completely free from pinholes, cracks, pits
or defects, which are detrimental to the intended use of the liner.
No F.R.P. 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
precast section joints or cast iron cover ring joint. 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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