For some applications, Formadrain liners offer flexibility in the choice of installation method. They can be pulled in place or they can be pushed in place.
An advantage of pulling a liner in place is that you have two lifelines – one at the upstream and one at the downstream — so you can pull from the house or from the main. Another advantage of pulling a liner is that, most times, you can easily pull it through the existing cleanout. Pulling Formadrain liners never requires direct access; they can be pulled through T’s and T-Y’s as well as through bends of up to 90 degrees.
One advantage to pushing a liner in place is that it can be a time-saver and, in some circumstances, is the better option.
If the liner terminates on a highway or a busy city street where permits would be required to set up over the manhole, it may be more time-efficient and less costly to push the liner, even if you have to dig an access point and install a cleanout to do so.
There have been jobs where a lateral was positioned mid-way between two manholes placed 600 feet apart. 300 feet is a very challenging distance to string the line, and sometimes it’s better to push the liner from the cleanout, assuming the cleanout is of a size and configuration that allows pushing.
The Cleanout is Important
Regardless of whether a liner is pushed or pulled in place, the cleanout is key. If the existing cleanout is suitably sized and configured (as it most often is), the Formadrain system is truly no-dig.
The cleanout must be wide enough for either method. If pushing, it must also be angled such as to enable pushing the liner. The ideal for pushing is straight access but you can also push through a Y. A T or a T-Y cleanout does not allow for pushing a liner because the downstream cap won’t negotiate the turn. A liner that is pulled in place will easily handle T’s and T-Y’s.
If pushing the liner requires installing a new cleanout, it may be more beneficial, more cost-effective or more time-efficient to pull the liner instead. If the circumstances are such that there is no option but to push, and there is no existing cleanout suitable for pushing the liner, installing a new cleanout will be necessary.
A potential limitation to pushing a liner is the length of the pipe. If the run is too long, the liner will be too heavy to push.
Push or Pull?
The decision whether to push or pull a liner is most often based on the nature of the job, the circumstances and the installer’s experience and judgement.
If there is an existing cleanout that is suitable for pushing a liner, or if they are going to install a new cleanout anyway, and the run is not of a prohibitive length, some installers will push the liner because it is more advantageous in some situations. Other installers will pull the liner even when pushing is an option because they like the flexibility of having two lines. Whether it’s better to push a liner or to pull it is a judgement call.
If You Have Questions
Formadrain licensees know that if they have any questions about the best installation method for a particular job, or if they ever need help with any aspect of a job, we’re just a phone call away.