Suggestions on how to keep drain tile in yard down?

Question

In my yard, I have a section of drain tile connected to my gutter that's had the top exposed since I bought the house. It was solidly in the ground, but probably 60-70% of what you see in the current picture was exposed. I dug it up and was able to dig under it about 2 inches until I hit some diagonally crossing irrigation lines. However, the way the tile is bent, it wants to pop into the air. I can stretch it away and push it down, but the tendency is for it to pop back up. As you can see from the side picture, I need about the entire 2 inches to have an adequate layer of soil for the grass.

My first attempt was to bury the tile under some of the heavier clay I dug up, and then just reseeded over the top. The ground was a little squishy like the tile was still moving a bit, but it seemed like it might work. However, the next day we got an absolute downpour. The intensity of the rain made it come shooting through the holes like a water fountain. On top of that, there was water flowing down the driveway and it washed away most of the top soil. Clearly this wasn't the fix.

For my second attempt, I purchased a section of 4 inch corrugated drain tile. I'm going to cut a slit in it and then wrap it around the exist section with the slit facing down. I also purchased some metal U shaped croquet wickets. The plan is to pin the drain tile with the wickets. My concern is that those wickets will still pull up when the ground is wet.

TL;DR How can I keep the drain tile "pinned down" and buried under the soil instead of popping up like it wants to do?

Solution That drain pipe was end-capped at the section I was working with, it wasn't connected to another pipe. I cut a couple inches off of the pipe, pulled it tight, and end-capped it again. I did use a couple of the wickets to keep things pinned down while I was working. There was a hole in the endcap, so I surrounded that area with a couple inches of pea gravel. Then I covered the pea gravel with top soil, and then just laid a piece of sod on top. So far the sod is surviving and the entire setup survived a heavy rain Sunday night. Thanks to everyone for their contributions.

Answer 1

You'll probably need to expose one end and pull it tight.

This would involve digging up from where it's exposed all the way to one end (or the other), then pulling it tight so that you no longer have the slack that's allowing for the bulge. Once you've got it pulled tight, you can cover it back over. Note that it probably doesn't have to be tight, tight (i.e., not under a great amount of tension), but just pulling out the slack.

When you're digging, you can carefully cut the turf and roll it up or flap it over, dig below it and make the adjustments necessary, then fill the dirt back in and put the turf back down if you're concerned about the grass.

Without the slack, odds are good that you won't need to worry about pinning it down in any way, but you're free to do so. I'd doubt that something like a croquet wicket would do much to hold it down, but it might contribute until the soil has settled again.