The intent of chemical grouting in sewer systems is to seal leaks and stop both infiltration and exfiltration. Groundwater infiltration into sanitary sewers not only increases flow levels and put additional pressure on the waste water treatment plant. As the ground water enters through the pipe joints and service connections it brings with it minerals from the soils and producing hardened calcium deposit on the joints and connections. Over time these deposits increase in size, reduce the flow capacity and cause blockages and backups.
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 (150 mm – 2000 mm)
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.
Service Interface Grouting (150mm – 600mm)
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.
Service Lateral Grouting (100mm – 150mm)
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.
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 your infiltration problems.
Structural Water Control
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 get 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.
Installing Grout Packers into 39” storm sewers
150mm to 1200mm Diameters
Northern Lites uses a fiberglass liner that is impregnated with epoxy resin, making it a very strong and chemically resistant liner. Depending on our client’s needs we can use a special high temperature and chemical resistant resin for industrial applications such as: pulp mills, petroleum plants, chemical plants and food and beverage manufacturers.
A point repair can be installed usually in only a few hours. The bladder is pulled into place and positioned with the use of a CCTV camera. Once in position the bladder is inflated and the resin is cured with high temperature steam.
Top – Hat and Lateral Relining
Top-Hat is a process of lining the city sewer main and the connection from a resident or business. This is where a lot of infiltration and root intrusion occurs. The process is very similar to installing a Section Point Repair and the liner material and resins are the same.
If your pipes are damaged or leaking, contact us for our rehabilitation services.