Plugging Sanitary Sewer Laterals (Trenchless?) 3

[FL21USF]

Hello,

We need to plug several sanitary sewer house laterals on only one side of the sewer which runs down the middle of the road. My first thought was to TV inspect the sewer and note the distances of the house laterals. A contractor could then dig at specific locations and plug the laterals.

Has anyone had success useing techless technology to plug house laterals?

Thanks,

Mike

 

[mitchell54]

FL21USF

In dealing with sanitary sewers there are many different ways to go about it. Unless you are in need of detailed line information such as the inside integrity I wouldn't recommend TV....it can be pricey. Smoke testing works for identifying lines, it is cheap and easy.

http://www.usabluebook.com/opnotes/OpNotes5.html

Now I am not clear on if you are plugging lines or abandoning lines. Because (following permiting guidelines) I have been able to plug lines in the manhole with a hydraulic cement. This negates any excavation and saves money. The only thing to keep in mind is confined space issues. I completed a rather large Sanitary Sewer Evaluation that started out with only a couple of as builts that were from the 50's so we didn't have much to go by. In order to get all the required information and complete the tasks at hand we used inflatable temp plugs, temp plugs, permanent cement plugs, TV inspection, smoke testing, and to top it off I even performed the classic "pour water at one end to see which pipe it comes out" trick.

If you can provide more details I can assist you a little more.

 

[SanEnr1]

What is the purpose of plugging the laterals? Are you permanently abandoning or temporarily plugging? Are you trying to plug them at the main or at the property line? I think your method would be dictated by your goals for the project.

 

[dicksewerrat]

If you are indeed abandoning the laterals one one side of the main, it can be done by trenchless methods. You should get a TV inspection crew out there to inspect the mainline first. there may be other problems with the main. and now is the time to repair them. One method would be to put a series of short repair sleeves at each service. another way if the mainline has structural problems would be to CIPP line the main and only reistate the laterals you want to keep open. what size is the line and like questions above, Why one side? Is there a development or new road going in?

 

[FL21USF]

First, thank you all for the responses.

The laterals are being plugged because the residences on one side of the road are being demolished due to the widening of a roadway. The contractor that is demolishing the house now is supposed to be plugging the laterals at the edge of pavement.

We have enough budget in the project to seal the laterals at the trunk sewer but I'm not sure if we need to go that far. We are not currently at the site to inspect the contractor’s work and if he does not plug the laterals correctly then that sewer will receive severe infiltration.

One thought we had was to wait until the contractor is done demolishing the houses and then do a smoke test. Even though the laterals are buried, we should be able to see smoke rising out of the ground if he did not plug the laterals correctly.

I agree that we should CCTV the sewer first to inspect the condition if we opt for trechless rehabilitation. However, if the line did not have a prior problem and a smoke test would determine if there were any leaks, should we plug the laterals at the trunk sewer?

Thoughts/comments are appreciated. Thanks again,

Mike

 

[SanEnr1]

It sounds as if, from your description of houses being demolished to widen a road, the road itself will be a major thoroughfare. If this is the case, I would definitely want to televise the sewer mainline to determine its condition before the project gets too far along. By completing the evaluation before pavement is installed you will not run the risk of having to excavate for a sewer repair after the road is surfaced.

Regarding the laterals, I would be concerned about leaving a pipeline that will never be used in the future under a new roadway; it leaves the potential for settlement if the lateral is ever compromised. I would be particularly concerned if the pipe material is VCP (which has many joints) or ACP (which is prone to shear breaks).

I know others may disagree with my opinion, but I would rather be safe and pay for the mainline to be evaluated by CCTV and the laterals to be terminated at the main connection rather than face the potential of a repair or sink hole in a brand new road.

As far as your original question of trenchless methods to complete the lateral abandonment job, I do not have personal experience of the technology being utilized in this manner, but I would suggest contacting a sewer grouting contractor. You would want to ask specifically if the contractor owned a "lateral packer". A lateral packer is a bladder inserted into the lateral service remotely from the mainline. Perhaps the packer could be utilized to isolate the service at the main and grout or cement could be pumped into the lateral from the open pipe at the property line? You would want to make sure that the pumping fills the entire lateral and does not leave an air pocket. This may require pushing the pump hose down the open lateral and pulling it back slowly as fill material is pumped into the pipe. As I mentioned before, this is only a thought. Start a dialogue with the grout contractor and he may have a better idea.

Good luck with your decision.

p.s. If you use the packer idea, the contractor will need to CCTV the mainline anyway and could be there to do any mainline grouting or repairs at the same time. You could get all the work done at once!

 

[dicksewerrat]

I guess that if that side of the main will not be used again, I'd inspect the sewer main. Then do a CIPP liner in the main. Designed for what ever condition you find. Just because there were no problems with the main doesn't mean it is in A-1 condition. I've had to dig up a few that never gave us a problem. If you plug these laterals at the edge of pavement you have created a number of very nice rat habitats. I would also look at the cost of the liner and the cost of digging the laterals and plugging. this can be done in one to two days and you won't have a number of soft spots along one side of the road. The excavation sites can be seen a few years after the road is built, unless you can get the contractor to compact to 95%+ proctor and verify each hole.

 

[HydroTripp]

There is a method called a "cold patch" CIPP which I allowed to be used on a job in one instance to repair a faulty FFP liner service pilot hole drilled in the wrong place. It delaminated from the FFP liner. I wouldn't recommend this approach. The CIPP lining of the entire main while only reinstating the services on the side of the road you are keeping sounds pretty good, but can you get the laterals plugged during the highway construction? This would have the advantage of eliminating possible annular leakage between the liner and host pipe at the manhole.
By the way, don't rely on smoke testing to locate these services. We have found smoke tests only locate some of the leaks. If the service is sheared deep underground you will never see the smoke.

 

[dicksewerrat]

Inspect the main, line it and then build the road. Where is this project? I may know lining contractors you can contact.

 

[FL21USF]

The project is in Hillsborough County, FL.

Thanks

 

[dicksewerrat]

contact Am-Liner East, Inc. they line in florida. 703-430-4120