Underground Services LTD

Mar-tech Grouting

The intent of chemical grouting in sewer systems is to seal leaks and stop infiltration and exfiltration. Groundwater infiltration into sanitary sewers not only increases flow levels, but also puts more pressure on treatment plant facilities. This may eventually lead to unnecessary construction of larger volume treatment plants, where simple grouting procedures would have sufficed.

Chemical grouts do not stop leaks simply by patching joints and cracks. Instead, grouting chemicals are forced through the joints and cracks, and into the surrounding soil to form a waterproof mass which cannot be pushed back into the sewer system.

Mainline Sewer Sealing

The mainline grouting process begins by air-testing joints to determine grouting requirements. If a joint fails an air-test, a packer containing the grout is inserted into the line through the manhole. After centering on the joint, the packer is inflated, and grout is injected through the joint connection. The grout creates a hard, impermeable gel around the outside of the pipe. The packer is then deflated, and pulled back for camera inspection, scraping the remaining gel ring leaving 100% flow capacity in the pipe.

Packer centering on leak

Injecting grout into leak

Service Interface Grouting

In order to seal services, a lateral injection packer is used. This packer is equipped with a lateral element which is inflated up the service line, and injects grout into the service. As the grout fills the annular area, it is forced through all open areas and into the surrounding soil, creating a gel ring outside the pipe and service connection. The lateral element is then deflated and pulled back into the lateral packer, scraping the excess gel as it retracts.

Packer moves into position

Inflated, filling annular area

Grout injected into lateral

Deflated, scrapes excess gel

Service Lateral Grouting

The Flexible Push-Type Packer is used to test and seal lateral lines from an above-ground access or cleanout. It has a 3.0 foot or 5.0 foot long grouting chamber. While air-testing, the center element also expands so that when grouting is completed, only a slight skim of residual grout is left behind. The preferred Test and Grout technique consists of pushing the packer to the far end of the lateral, and bringing it back in 3 or 5 foot increments, (the length of the grout chamber), testing successive sections and grouting those which don’t meet test requirements.

Soil Stabilization

Infiltration in sewers causes the erosion of soil, washing fine soil particles into the sewer system. This soil erosion leads to sinkholes, undermining the pipe supports. As a result, the structural integrity of the pipe is endangered due to the washout of backfilling material. To resolve this problem, the soil stabilization process is often used.

Soil stabilization works by pumping grout into the soil surrounding the outside of the pipe. The grout quickly forms a strong, permanent seal around the pipe, holding it in place, and reestablishing the density of the eroded soil.

It is important to act quickly to stabilize soil where infiltration has occurred. Pipes showing infiltration in Stage 1 (see diagram below), are good candidates for soil stabilization. If these problems are not treated however, the pipe will eventually degrade to Stage 3 Failure (below). Treating infiltrating pipes early with soil stabilization is the safest and most economical way to solve you infiltration problems.

Manhole / Structural Grouting

Despite the best efforts of architects, engineers, and contractors, concrete structures sometimes move in unanticipated places, and cracks appear. If the movement which caused the crack stops, the crack plane becomes stable. However, many cracks do not stabilize. Instead, they continue to move throughout the life of the structure due to thermally-induced forces within the structure, or due to the soil moisture changes.

For over 40 years, chemical grout has been used to stop leaks in basements, commercial buildings, dams, manholes, parking garages, reservoirs, storage tanks, subways, tunnels, wastewater treatment plants, and many other structures.

Protection Against Cyclical Structure Movement

When concrete moves, it usually cracks, and when it cracks, it usually leaks. Any rigid material used to fill the crack is doomed to failure because the concrete will probably move again. If the crack gets smaller, the rigid patch material will shatter. If the cracks gets larger, the material will crack and separate, creating a new leak.

Chemical grout cures into a flexible, rubber-like material which can withstand tremendous compression or expansion without being harmed. As a result, it will permanently seal cracks in concrete structures against infiltration or exfiltration.

Video Explanations

Chemical Grouting Joint In Main

Sealing Unlined Lateral Connection

Grouting & Lining Together

Sealing Lined Lateral Connection