Septic tank riser

Old 03-14-20, 06:19 PM
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Septic tank riser

I have two concrete septic tank lids. They are 22”x22” squares with a diagonal of 31”. They are 5” thick concrete. This means I need a riser that is minimally 31” diameter. But I do not find one this size. I want to eliminate the heavy lids and just install a riser with a lid at grade. What would you do?

Old 03-15-20, 04:47 AM
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Even in my small town the local septic tank company stocks several types of risers. Most are round and the corners of your square opening will be covered with a 30" diameter riser. I like the plastic risers that have a concrete skirt cast on the bottom. You clean the top of your tank and lid area. Apply a heavy bead of bitumen caulk/sealant. Then set the riser in place. The size and weight of the concrete skirt hold it in place. Then you add on however many plastic risers you need to get to the desired elevation. When installing the lid don't forget to screw it in place so it can't be removed by children.
Old 03-15-20, 05:54 AM
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Two houses ago my tank was around 24" below grade and was a pain the first time we pumped. Septic guys got me plastic risers (heavy corrugated construction) and heavy plastic lids with SS hardware.

Installed so they were 6" below grade, piece of cake to install!

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