For use on both residential and city streets, parking lots, and areas that need to remove standing water from the surface, manholes provide an important function for buried infrastructure. By allowing access at critical points for sewers and wastewater systems, manholes allow for repair or maintenance when needed.

This manhole is made with an 8-foot base, which can be augmented by other sections from two to eight feet. The transition section, often referred to as a reducing slab, is eight inches thick with a 48-inch opening. The eccentric cone is three feet high with room for a 25-inch cover.

Safety accessories, such as ladders or rungs, are easily added during the casting stage. With your specifications, we’ll also create a Perfect Base for the manhole, improving the efficiency of your system. For more information about this manhole, click here to download the .pdf or continue to the bottom of the page.

Precast Benefits

From there, the base is poured, strengthened, and shipped to the site or added to the manhole. Once the excavation is complete, the manhole is ready for installation. That’s what makes precast manholes so much easier – and cheaper – to work with than poured-in-place (PIP) concrete.

With PIP, forms need to be set in place, the concrete needs to be poured, and time spent waiting for it to strengthen. Holes of the incoming and outgoing pipes aren’t as exact and additional preparations are needed before backfilling. That takes time, and in the construction industry, time is money.

With precast, fewer workers are needed for installation as the manhole has already been poured and strengthened. When excavation is complete and bedding in place, the unit is ready to be lowered. Less time, labor, and worry about weather conditions make precast the ideal choice.

Strength and Durability

Precast concrete also saves money over the long term because of its longevity. Made to last a century, there’s no need for repair or replacement of precast concrete manholes. Resistant to rust, rot, or decay, concrete also stands up to animal infestations. It is truly a set it and forget it product.

Which is important if being used on a bust downtown street. Along with normal automotive traffic, precast manholes are designed to stand up to stresses from above. Fully loaded semis, heavy box trucks, and other heavy haul machinery is no match for our manholes.

If you have a need for 72-inch eccentric manholes for a new subdivision, business park lot, or other applications, contact Columbia Precast Products. We’ll make your manholes to Washington State and Oregon State Department of Transportation specifications and have them ready for when you need them.

Click to download as a PDF.

72in Manhole With Eccentric Cone