What are these two Sewer Pipes Coming up Out the Ground?

Question

We recently had the old terracotta sewer line replaced that comes out of our house to the main sewer line

There are now two pipes in addition to the sewer clean along where the guys dug up

I planned to use a roto tiller on dug up area and plant grass. This first pipe presents a small problem though.

The second pipe is where I want the garden to be, I'm really unsure how this pipe affects that plan. Is it safe to plant anything around the pipe? Will the plants grow into the pipe and ruin it? I'm unsure...

The Question

What are these pipes? What purpose do they serve?

Bonus Questions

• Is there anyway I can hide these pipes? I wouldn't think I could bury them, but if I can that would make hiding them very easy. If I can bury them and they're too tall to be buried, can I cut them down in any way?
• Does the pipe affect my garden in anyway? Or can I plant around it

If you guys need more info or if my question(s) needs changed, let me know and I'll do it ASAP. Thanks.

Note

I don't believe that these pipes are the sewer clean. The sewer clean is closer to the house in this picture, if I'm not mistaken

Answer 1

They are probably additional clean-out-points - my local inspector wants one every 50 feet (15 meters) along the line. But my comment that you should ask the people who put them in, who would know, stands as the correct way to figure that out.

If so, they should remain accessible, but be protected from sunlight, as they appear to be PVC. You can paint them for basic sun protection, or my preferred approach is to build a small rock or brick wall around and put a large flat rock or patio block on top of it - easy to find, easy to access, but out of sight and out of sunlight.

Should not affect your planned garden particularly, though you should beware of the possibility that they MAY not be vertical all the way to the buried line - they might angle towards the street before the connection to the line, so when digging near them, dig slowly and carefully. Non-perforated PVC pipes are far less "root infiltratable" than clay pipes were.

Answer 2

Answer to the bonus question:

Since they are almost certainly just cleanouts, you can cut and re-cap them below ground level. To keep it accessible, purchase a valve box at your local hardware store and bury it flush with the ground.