Sewer Sealing

We seal leaks in sewer lines. The joints and lateral service mouths are traditional weak points in the sewer system and are generally where much of the clear water infiltration in a sewer system originates.

Sewer Joints

The "water tightness" of a joint is a function of the pipe material, the joint mechanism, nature of the effluent and the quality of installation of the pipe. When joints leak they carry with them the bedding surrounding the pipe, and over time the pipe sags and cracks or large voids form around the pipe and is a major cause of road collapses. Chemical grout injection is designed to re-gasket and fill the voids around the pipe to stabilize and prevent future pipe degradation.

The big problem is knowing which joints leak. Typically infrastructure owners or managers will use CCTV inspection equipment in an attempt to locate the "leaking" joints. This is fine in theory but the reality is that Infiltration fluctuates over time and it is not often possible to inspect the sewers during this time critical event when they are leaking. Much of the CCTV inspection work in our neck of the woods is unfortunately done during dry periods that often corresponds to the municipalities tendering cycle. (we are often hired to inspect sewers at the wrong time due to municipal budget timelines)

The solution to the problem is to test and seal all joints within a sewer line. This is a well established practice and is described in detail in ASTM F2304-03 . Each joint is individually tested and if the joint passes the air test (does not leak) the packer in moved to the next joint. The process is repeated for all joints in the sewer. Where joints fail the pressure test chemical grout is injected into the joint to re-gasket it and then it is re-tested.

The process is very efficient and rules out speculation as to which joints leak. We often get requests from clients to seal individual joints that are seen to leak on a video some time ago. When we get there to fix it the joint is typically no longer leaking. We seal the joint to prevent future infiltration but are required to leave all the rest of the joints alone as it is assumed they do not leak. We feel that it is a better practice to test and seal all the joints if one is leaking (after all we are already there with all the equipment to do the work -and the hard part is getting in the line with the equipment) to make sure that the next joint in the line does not fail a few weeks down the road once the water pressure becomes elevated due to the sealed leak. We call this process "leak migration" and is very common in circumstances where an isolated approach is taken towards infiltration reduction.

Lateral Service Connections

The second weak point in sewers is the junction of the lateral service connection and the main sewer line. The potential for infiltration increases when factory tees are not used for service connections. In the past it was common practice to "bash in" lateral services and this is now coming home to roost for many infrastructure owners.

This area can be tested and sealed just as the joints can within the sewerline. The process is well defined and described in detail in ASTM F2454-05.