Manhole Liner Solutions

Manhole Liner Solutions

The Predl Base Liner provides complete corrosion protection for the entire manhole base. Internationally proven in over 1.5 million manhole structures, Predl Liner Systems offer the most complete, versatile design and manufacturing process for corrosion resistant, water-tight and maintenance reducing municipal sanitary sewer manholes. Since 1988 in North America, nearly 50,000 Predl Base Liners have been installed, including Pierce County in WA State, which has installed over 10,000.

The Predl Base Liner is a molded, wastewater resistant PP or FRP thermoplastic concrete protective liner (CPL) system of reinforced polymer with a thickness range from .12” – .20” (3 – 5mm), mechanically bonded with the concrete base structure during the precast concrete process.

Encompassing the entire interior configuration and surface of the manhole base in one piece, the Predl Base Liner demonstrates design criteria essential for long term manhole protection and efficient wastewater transmission.

The proven design of Predl Base Liners eliminates several sources of potential errors in manhole base production insuring the correct layout right from the start. The design makes manhole base production and installation easier than conventional products.

The bottom of the Predl Base Liner has exposed angular aggregate and wire coils for a strong mechanical bond to the concrete. It is cast upside down on a support cone with monolithically poured concrete around the inverted base liner. The one-piece construction of the base liner makes the application safe and easy.

The Predl lined manhole is formed upside down so no reworking is required; this means quick and safe production with attractive cost savings. Conventional manhole bases, especially those with concrete benching, are subject to attack from aggressive wastewater and will require expensive repair work. Such problems are a thing of the past with Predl lined manhole bases.

The pipe-specific bell design ensures a water-tight connection between the Predl Base Liner and the pipe system, regardless of changes in direction and gradient. The result is a perfect invert to channel alignment every time. When pipe stubs are used the compression seal gasket ensures an additional flexible connection with allowance for pipe transition and tension-free tolerance for various settlement phenomena.

Unique solution for corrosion, abrasion, exfiltration, inflow and infiltration

Engineers will specify corrosion resistant pipe or some form of pipe protection, but neglect to specify protection for the concrete manhole structure in the sewer system.

Civil Engineers, like Robin Ordonez (Assistant Wastewater Utility Manager (retired), Pierce County Public Sewer Utility) working in public utilities specify Predl Liner Systems solely because of their unique protection against the corrosion and abrasion of wastewater while eliminating turbulence because of “factory precision”, smooth, nonporous flow channels, and secure pipe connections due to accurate invert alignment.

Precasters prefer Predl Liner Systems because they can efficiently manufacture a lined protected concrete manhole base. Coring holes and the cost of resources to do old-fashioned, hand-formed concrete channels or brick and mortar benching are methods of the past.

Contractors appreciate the ease of installation. The joints between the manhole risers are finished with an impervious seal using either a capped heated extrusion weld or butyl caulking. Once the manhole with a Predl Base Liner is set it is ready to be put into service. Predl Bells provide water-tight connections which resist settling, expansion and contraction stresses after the manhole has been installed.

Adherence to municipal design standards and allowances for Inflow and Infiltration (I&I) in sanitary and wastewater sewage systems can be accomplished with Predl Base Liners. These liners are internationally recognized as a state-of-the-art technology. The Predl Base liner provides quality protection through the manhole base with the same design quality as modern sewer pipe materials.

The non-skid surfaces on Predl Base Liners are made of wastewater resistant plastic; they are safe and secure for maintenance staff in a confined, difficult working environment.

A Durable, Efficient, Cost-Effective Solution

The concept behind the Predl Manhole Base Liner has been developed systematically over time to guarantee successful results. Predl’s Liner Systems are the logical next step in the progressive development of sanitary sewer systems.

Predl Concrete Protective Liners (CPL) for Manhole Riser Sections and Lift Stations are manufactured with wastewater resistant PP/FRP thermoplastic, providing complete protection for precast concrete structures from the corrosive effects of oxidizing hydrogen sulfide.

While standard Predl Base Liner production allows for a 3 inch (7.6cm) vertical sidewall return for the entire circumference of the manhole base, extensions of this “skirt” may be integrally molded with the base liner in lengths up to 52 inches (132cm). This permits the monolithic construction of a fully-lined manhole without joints which require only “topping off” the structure with a Predl Cone, Convertible Collar, or Flat Slab Top Liner.

A high strength mechanical bond with concrete is achieved by using aggregate and steel lattice or similar anchoring systems. Pipe penetrations are molded at the appropriate location during manufacturing. This negates the need to field core and attach ancillary connections later. Installation time and costs are substantially reduced.

Concrete is monolithically poured around the liner while it is supported in an inverted position ensuring the utility of a minimum 4000 P.S.I. monolithic casting. A high-strength mechanical bond between liner and concrete is achieved by way of a well-proven interface consisting of specifically-sized clean aggregate and steel coil/lattice bonded to the bottom of the liner. With vibrated concrete attaching itself to this continuous multi-faceted bonding medium, intruding forces of groundwater backpressure is not of concern.