Plastic plugs are just fine.
I just replaced the standpipe in the front yard, and now it needs to be capped off. It is the "standard" 4" pipe, plastic. I've seen the type that is glued into the pipe, with a screw-in cap. The cap has a square knob on the top for a wrench. Is this the proper type to use, or should it be a metal cap?
Use a plug with slotted recesses on top rather than the square lug. Your lawnmower will like it a lot better.
As suggested above the cap would be best recessed to for obvious reasons.
However, also consider that many counties are now requiring brass caps.
The reason is so they can be located if they become buried or non-visible. If its not new construction you can get away with plastic, but if its low to the ground or may become buried you might want to consider brass cap for easy locating in future.
Plumber in Columbia SC
Plumbing Solutions LLC
Residential Plumbing & Repair
I like the look of the solution in the picture. It should be perfect for me, as the cleanout comes up in my front garden, therefore no lawn mower complications! Also I can easily control the height, so burying will not happen. I am reluctant to do anything that is metal, because it eventually corrodes and cannot be opened. I have a brass cleanout inside the house in the basement floor that was buried in the cement floor for 34 years until I finally found it. Now it cannot be opened. If that happened inside, I can just imagine what an outside cap would do.
Thanks again for this. I will buy the parts today!