Sanitary Manholes
SUPERIOR STRUCTURES FOR SANITARY AND STORM SEWERS
With superior strength and durability, precast concrete manholes and structures provide a versatile and economical alternative to cast-in-place concrete and other materials. Cemcast Pipe and Precast offers a full range of manholes. Manholes are ideal structures for sanitary sewer or storm sewer applications. As manholes are round structures, they are capable of accommodating pipe at any angle of entry.
All Cemcast manholes are made from self-consolidating concrete. This gives us absurdly high concrete strengths which exceed 7,000 psi. SCC produces an exceptionally smooth finish, allowing us to create inverts that are ultra-smooth with a low coefficient of friction. SCC also gives us perfect joints, which means that our manhole vacuum tests go smoothly and efficiently. We use go/no go gauges on all sanitary manhole product before it is put in the yard. All of this ensures our manhole product will vacuum test in the time it takes to perform the test.
Manhole Connections
There are a few common products that can be used to create a 13-psi connection between pipe and manhole. The first product is the A-LOK gasket. A-LOK gaskets require the smallest opening in the concrete structure. A-LOK gaskets are compression connectors so there is no boot band required to properly torque. A-LOK guarantees watertightness to 13 psi for the life of the structure. In addition, A-LOK gaskets can be used to make watertight storm sewer connections.
We always recommend A-LOK gaskets for deep sewers and large pipes. Boots are another product that can connect pipe to manhole. Boots allow the contractor the greatest amount of flexibility when installing pipe into a manhole. These are mechanical fixtures, requiring proper tensioning of the boot band in the plant and in the field to ensure watertightness to 13 psi. Boots are the most common connector used in our region.
Our Process
Sanitary manholes are available in standard sizes ranging from 48” to 120”. Lined manholes feature GSE Studliner, with joints welded in the field by Cemcast. The GSE Studliner protects the manholes from concrete degradation via acid attack from sewer gas. We weld the manholes following installation and spark test all joints. We also use premium lift anchors from Lane or CONAC in each manhole. No special keys or tools are required to use these lift anchors.
Manhole Inverts
Manhole Inverts are all poured using the A-LOK forming system. This ensures a smooth flow through the manhole. The forming system, combined with our SCC concrete mix, produces a wonderfully smooth, continuous invert free of sags and dips. The forming system ensures the inside dimension of the invert is the same as the inside dimension of the pipe. Because our inverts are formed to mirror the inside pipe dimensions, sewage does not swell or swirl as it passes through the manhole. We can also epoxy coat the invert. In conjunction with the GSE Studliner, an epoxy coated invert creates a manhole that will last for 100 years.
Transition Slabs
We are able to cast a 48” gasket joint spigot with any lid or flat-top. This means an engineer can specify a structure larger than a 48” manhole riser around the pipe and then come to the surface using a 48” manhole riser. The transition slab eliminates the need to build a much larger structure all the way to the surface, saving money. The joint is a single-offset gasket spigot, so it is watertight.
