Manhole Sealing

"Chemical sealing of voids behind the wall of MH's is an effective and proven method of stopping water infiltration".
DM Robichaud Associates Limited

We are experts at sealing leaking manholes and other underground sewer structures. Structures pose special challenges compared to sewer pipes because there are so many different components and therefore many more types of problems and sources for leaks. On a positive note, structures also typically have much better access for men and equipment and therefore there is a wider variety of potential repair solutions.

Area 1 - The manhole cover is a typical major source of inflow of water into the sewers. However a simple inflow bowl placed just under the cover will prevent water from entering the manhole. Our inflow bowls are unique among all others as they are specially designed to not rust or rot, have a pressure relief valve, long safety strap and are designed to not raise the MH cover up above the frame, meaning our bowls do not cause problems for snow plows in the winter time.

Area 2 - The top brickwork of the manhole suffers from the freeze thaw cycle over time and causes the familiar sinking manhole phenomena that we have all observed driving our cars. Unless the damage is too severe the area can be be effectively repaired from within through standard masonry techniques. An expandable gasket is then installed that stretches from the top of the 1st precast section to just under the frame. The gasket is held in place by stainless steel bands preventing water from entering the MH from this area. The gasket moves with the freeze thaw and stops the washing away of the fines in the water that causes the settling around the MH.

Area 3 - Leaks from holes in the walls, between precast sections, in the benching or around the pipe where the pipe enters the manhole wall are effectively stopped using a chemical grout. The grout is injected through and near the leak and expands to fill the void area behind the MH wall, therefore stopping the water from entering the MH. See photographs below.

Our experienced grout technician uses specially formulated grout products manufactured by 3M and Multiurethanes Inc that are specially designed for water stop in sewer systems. Our technician is factory trained and has 15 years experience applying chemical grout products to stop some of the most suborn and difficult leaks. We have the specialty application equipment that are required to apply the products and get the job done right. In the past several years we have sealed several hundred manholes for Municipalities and Contractors throughout Ontario.