Manholes play an important part when it comes to keeping sewer and storm drain lines free of debris, running smoothly, and providing access for workers to perform maintenance or service. Depending on the usage, manholes can come in a wide variety of sizes. With additional sections, manholes can be almost any height (as long as code and requirements allow).

The 60-inch manhole with flat top or concentric cone can use a standard 7-inch cast iron frame and cover or a 3-inch suburban frame and cover. Manhole sections are held together by gravity and sealed with gaskets or mastic to prevent infiltration or exfiltration.

Channeled Base Units

In addition to the traditional manhole compositions, Columbia Precast Products highly recommends the use of precast base channels. These channels can be added after the manhole base has been made or as part of the base during production. The Perfect Base is a product used for 60” diameter manholes to keep sewage lines running efficiently.

As sewage pipes bring wastewater into and out of the manhole, the integrity of the pipe diameter and flow capacity needs to be maintained through the manhole. Traditionally, a channel would go into the manhole after it had been installed, by hand.

Today, utilizing the Perfect Manhole Base technology, bases can be made with a monolithic channel to accommodate whatever pipe configuration and flow characteristics are required. This information is taken from the construction plans, imported into the Perfect Manhole Base software, and built into the manhole. Channels for two, three, or more openings can be created in a variety of sizes. The Perfect Manhole Base technology creates a smooth, accurate channel that improves flow and reduces the risk of obstruction caused by debris.

Why are manholes needed in the first place? To keep miles and miles of city sewer lines functioning as designed while providing access points for routine maintenance.

Are you a homebuilder planning a new subdivision or a municipal worker planning new infrastructure? Reach out to Columbia Precast Products to see how we can help. We are familiar with both the Washington and Oregon Departments of Transportation and can manufacture as few or as many as you need.

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60in Manhole With Flat Top