SCOPE:
This method utilizes prefabricated Polypropylene (PP) liner sections, which are field inserted in existing concrete or brick sanitary sewer structures, either for rehabilitation or retrofit applications.
Option 1 requires excavation and removal of existing manhole cast iron frame with lid, chimney and corbel-cone (or top slab); insertion of the prefabricated Polypropylene (PP) liner sections and installation of a new precast F.R.P. or HDPE/PP lined corbel-cone (or top slab).
Option 2 only requires the removal of the frame with lid. The Polypropylene (PP) liner sections can then be taken down into the existing structure and has to be welded together in place. .

Polypropylene (PP) LINER MATERIAL:
The prefabricated Polypropylene (PP) liner sections shall be composed of 100% polypropylene with a minimum thickness of ¼"(6 mm). The sections shall be non load bearing components which are resistant to the chemical environment found in the waste water collection system to which they will be exposed. The outer surface of the liner shall have opposing vertical ribs to lock the liner into the grout upon hardening.

The Polypropylene (PP) liner sections diameter shall fit into the existing structure such that a minimum of 2" (50 mm) annular space is available for "grouting". The assembled prefabricated Polypropylene (PP) liner sections shall conform to the height of the corresponding manhole structure. Pipe connections shall accurately accommodate all existing inlets, outlets, drops and cleanouts and are to be "plumbed" through monolithically attached "Factory" installed pipe stubs. Watertight flexible rubber repair couplers and / or rubber boot seals are to be used as noted in the drawings or as directed by the engineer.

The contractor shall measure the existing manhole prior to installation to determine critical dimensions including (but not limited to) structure diameter, height, pipe connection elevation, type, size and pipe angle location. The contractor shall be responsible for liner installation and fit.

INSTALLATION:
GENERAL: Excavate an area around top of existing manhole sufficiently (width and depth) to facilitate the removal of manhole frame, chimney, corbel-cone (or top slab).

EXISTING STRUCTURE: Prepare structure interior, pressure wash or sandblast to remove all scale, loose material, grease and sludge build up. Remove loose or unsound concrete and mortar. Remove protruding brick, steps and hardware (lift station - pumps, plumbing & controls) that will interfere with liner installation. Active leaks (infiltration) shall be stopped with hydraulic mortar (or other approved materials). The interior surface should be tested for pH to insure all acid contamination has been removed. All other structural repairs deemed necessary shall be performed.

NOTE: It may be necessary to plug sewer liner or cover invert to prevent extraneous materials from entering sewer liner. “by-pass” pumping diversion may be required to maintain sewage flow.

MORTAR BENCHING / CHANNEL INVERT AND LIFT STATION FILLET
All required remedial work is to be performed per the governing utility specifications to insure watertight pipe connections and proper sewage flow. The benching or fillet shall be leveled or modified to insure proper bedding and vertical alignment of the Polypropylene (PP) liner sections within the vertical shaft of the existing manhole or lift station. The mortar benching shall be raised to a level just above the crown of main channel inlet to accommodate the proper installation of the Polypropylene (PP) liner sections.

MORTAR BENCHING SEAL A "bedding ring" of quick setting grout mixture shall be placed on the benching to achieve a good bottom seal in order to prevent loss of grout from annular space between riser sleeve liner and interior manhole wall. Polypropylene (PP) liner sections shall be lowered into "bedding ring" on prepared mortar benching. Allow sufficient cure of grout "bedding ring" before proceeding.

* IMPORTANT NOTE: Care must be given to insure proper vertical alignment of Polypropylene (PP) liner sections to maintain proper annular space orientation for full height of new liner assembly with existing structure. If existing structure is "out-of-plumb" a miter cut adjustment must be made at the bottom end of the first riser liner section.

A six to twelve inch height pour of high strength pumpable bonding grout like Master Builders www.masterbuilders.com or Euclid Chemical www.euclidchemical.com shall be placed above the initial bottom seal in the annular space between the liner and interior structure wall.

** IMPORTANT NOTE: Polypropylene (PP) liner section interior must be fully supported during grouting pour with expandable support ring fixture, inflatable rubber bladder or bracing / shoring forms to maintain proper riser liner geometry. Allow sufficient cure of grout before disturbing support fixture to avoid bulging or deflection of Polypropylene (PP) liner sections. If existing structure has had extensive corrosion and structural deterioration / reduction of wall thickness, the governing utility may require inserting wire mesh or rebar reinforcement in annular space.

Deep manholes/lift stations may require multiple Polypropylene (PP) liner sections which shall be assembled, sealed/welded, supported and grouted in stages as described previously in this specification. The Polypropylene (PP) liner sections shall be constructed to the prescribed height with the top of the "final" riser section having a level mortar "butt type" joint to allow for installation of either a new lined precast corbel-cone (PP or F.R.P.) or F.R.P. lined precast top slab.

The new lined precast corbel-cone / top slab shall have an I.D. corresponding to the I.D. of the Polypropylene (PP) liner sections. The internal flange joint between "final" Polypropylene (PP) liner and lined precast corbel-cone (or lined precast top slab) shall be sealed with approved preformed butyl strips.

A GU HDPE Convertible Collar shall be installed on top of the lined corbel-cone / top slab with masonry grade adjustment (brick courses, field poured concrete or precast grade rings) for setting cast iron frame. The Convertible Collar shall be inserted through compression seal gasket mounted in the lined corbel-cone / top slab with appropriate GU Convertible Collar gasket flange design.

The lined corbel / top slab having appropriate access way ID design and cast iron frame shall be sealed with approved preformed butyl strips. The manhole/lift station frame and lid shall be set to conform accurately to the finished ground or pavement grade as shown on the drawings or as directed by the engineer. Non-shrink mortar shall be used for installation of corbel-cone (top slab), masonry grade adjustment and cast iron frame in customary manner for proper structural assembly and to prevent ground water infiltration.

Interior surfaces of liner shall be completely free from pinholes, cracks, pits or defects, which are detrimental to the intended use of the liner. No Polypropylene (PP) liner sections shall have holes or openings, which will permit the passage of liquid or gases through the liner wall to the mortar/ concrete. There shall be no exposed mortar / concrete through inside liner surface to include (but not limited to) riser section joints, adjustment liner section joints, pipe penetrations and cast iron frame. All mechanical anchor attachments through liner surfaces must be sealed with an elastomeric sealant approved by the Polypropylene (PP) liner manufacturer.