The fiberglass insert reduces the annular space on a 48” manhole to about 42”.
The manhole cone and chimney must be removed by digging up and later replacing or repositioning the cone for fiberglass inserts. The process is likely to take 2 or 3 days.
With FI, it is very difficult to seal at the floor and around the inlet/outlet pipes as well as incoming laterals on the wall.
For FI, the soil must be recompacted and paved, which is a disruption of traffic flow if the manhole is in the street.
The fiberglass insert must be molded somewhere.
With fiberglass inserts there is no bond to the host structure.
With the use of fiberglass inserts, the contractor has to use a slurry mix to backfill behind the insert, to fill the annular space. This slurry mix cures to less than half the strength of the precast concrete of the rest of the manhole wall.
Poly-Triplex Liners
The Poly-Triplex Liner conforms to the host structure and bonds to it, adding less than ¼” of thickness.
The PTLS is completely cured in place with no digging and takes about one-half a day per manhole.
The cured PTLS is monolithic, with no chance for leaking anywhere the liner is in place, including the edges of the liners.
PTLS does not affect the soil surrounding the manhole.
With the PTLS, we use the existing structure as a mold so there is always a custom fit.
The PTLS is monolithic with the host structure and strongly bonded to it.
The PTLS requires the addition of no other product to complete the liner and the pressurized cleaned old wall is completely cured and left in place with the new PTLS cured on top of it already.
PTLS also does the bench and the metal ring up to the lip where the lid sits and there is no loss of annular space.
Finally: The fiberglass insert product costs more and is more labor intensive than the Poly-Triplex Liner System.
