As one of the largest manholes we manufacture, the 96-inch manhole with a flat top is an ideal solution for high-flow storm drain and wet wells for sewer systems. They can be built up to 50 feet deep using sections that range from two to eight feet.

Our manholes are reinforced to meet ASTM, all Washington State Department of Transportation and Oregon Department of Transportations specifications. Gaskets and mastic are used to seal the joints and provide an air-tight fit between sections and tops. The top itself is a foot thick.

Tops are made to accept cast iron covers and a range of access hatches. In addition to the manhole itself, Columbia Precast Products can add steps or ladders to the inside of the manhole for an added layer of safety. More specifications can be found in the .pdf below or downloaded here.

More Protection for Your Investment

Columbia Precast Products mixes antimicrobial additives into the concrete to combat microbial induced corrosion. This happens when the temperature of the sewage reaches a certain point, releasing gas.

This gas interacts with the air, creating bacteria that feed on the surface of the concrete. This additive – which is becoming a requirement in many Washington and Oregon jurisdictions – repels the bacteria. Our manholes are designed and built to last 100 years. These additives make manholes that much more durable.

Have a need for several 96-inch manholes for residential or industrial projects? Contact Columbia Precast Products. Made in our controlled facility, we are able to produce as many pieces as needed well before they’re needed at the job site. That way they are ready for installation as soon as the excavation is complete.

Columbia Precast Products was the first buried infrastructure facility to earn SMaRT Certification. So you know you’ll be getting a consistent, quality product that’s also good for the environment. Contact us to see how we can help your private or public project.

96″ Manhole – With Flat Top