How to set a sewer manhole

Setting manholes is an old tradition beginning in the Indus Valley almost 2000 BCE. Many Roman manhole covers still exist with the SPQR notation on them. When the European expansionists arrived in the Americas they were amazed to see an Aztec sewer system vastly superior to their own (ie throwing it in the streets and bringing about the great plagues).

Today we set manhole covers over the structures set in the ground to allow access should something go wrong. Whereas storm sewers are unlikely to carry filth and foulness, it is assumed that all sorts of nastiness may pass through a sewer line, and thus the porosity of the system must be maintained to a minimum. In most cases we are expected to achieve ~4psi during a smoke test of the system. This ensures that there are no major leaks where said nastiness may pass through the pipes and into the ground water.

Setting the covers is an essential part of the test. Not that the stuff in the pipes is likely to rise up that high, rather that it's a common point of failure and simple enough to fix in a few simple steps.

1) Clean the surface up nice 'n purty.

2) Slap some tar on there - we like Clipper Ship tar - it's swell.

3) Flipper over and check the level - you may need to slope it to work with the existing asphalt - when all else fails use your brain.

4) Mix up some mud. We like to blend 50% non-shrink grout (red bag) + 50% sand and mortar mix (yellow bag). Mix it very wet to get underneath the manhole. FYI - the non-shrink stuff smells like coke, however I'm told it tastes lousy and won't numb up a thing unless you swallow a few pounds of it. It's great stuff though - really helps to prevent cracks later.

5) Slop the stuff on there.

6) and once the mortar gets a bit drier use what's left to seal the inside.

Added Jan 15 - Had a tough time getting the manholes to hold -10Hg during the vacuum test a few days ago. We lined all the seams with carboline epoxy yesterday, let it harden overnight (plus almost an hour per manhole with a 70,000 BTU jet furnace to complete the setting) and tested today - none of the manholes leaked so much as a pound.

yippee - a new manhole. humorously enough these are made in the Capital Foundry in India - known to be one of the worst places on earth to work - conditions are so rotten the discovery channel did a series on them. Pictures of a bunch of small brown people running around shoeless pouring 3000+ degree steel so that we can drive over manhole covers. Aren't we the lucky ones!