For applications where the depth of a Packaged Fiberglass Manhole has been undersized, Openchannelflow offers Manhole Extensions.
These Extensions are designed to provide standardized solution integrating the height modification, top, and ladder into a single drop-in-place piece.
Manhole Extensions are also useful when a site is being redeveloped and teh top style of the manhole now needs to be changed. A common example woudl be manhole placed in a previously grassy area that is being converted into a parking lot.
Originally a Domed Top style manhole (sticking a foot above grade) would have been appropriate, but now a H-20 Reducer style capable of withstanding traffic loading (and not extending up above the paved area) is needed. Here a Manhole Extension can retrofit an entirely new top style to an existing manhole – protecting the owner’s investment for years to come!
Installation is accomplished by:
- Removing the existing top / hardware (retaining it for remounting if desired – making sure to tape pictures / measurements of the mounting locations)
- Dry-fitting the extension on the exposed manhole barrel (marking how far down the manhole barrel the extension slip flange extends and where the ladder sections align)
- Removing the dry-fitted extension
- Wiping down / cleaning the area on the manhole barrel where the extension slip flange will cover (Acetone works well)
- Thoroughly buttering the now clean / dry area with the provided construction adhesive
- Sliding the extension into place – making sure to align the ladder sections
- Bolting the ladder sections together with the reinforcing splice plate and hardware provided
- Bolting (if necessary) three or four section of the manhole / extension slip flange together
- Reinstalling the existing top / hardware removed in Step 1
At a prepared site, the installation of an Openchannelflow Manhole Extension should take no more than a short morning.
