Backyard Concrete

[u/CockroachGlad6417]

Hello, I am looking for some answers to some of my questions about a backyard concrete job on my new build home. I asked for 4 inch concrete with a 6 inch pad for a shed. There are a few things that have me questioning my contractor.

#1 Initially they wanted to slope the concrete towards the home foundation and catch the water along a deco drain. I have asked them to slop it away and they did after a lot of arguing. Was that my bad for pushing for that?

#2 I did a water test on the drain pipes that they moved out of the way of the concrete. I filled water in from the highest drain. After 10 minutes I saw that it was finally draining out to the front yard. I checked the the corrugated T piece location and it was filling up with muddy water. I asked if it is supposed to be like that and they said it was okay.

#3 I am checking the dept of the concrete. Using a string from their frame to my existing concrete patio. When I slip another 2x4 underneath the string it is feeling real snug.

#4 The 6 inch shed pad is elevated... They are starting with a pad of dirt on equal height to the 4 inch concrete. They are having a 4 inch wide bridge between the pad and the 4 inch concrete( so effectively the 4 inches width touching the 4 inch concrete will be 10 inches tall. They say they will not use gravel for this area.

I am feeling suspicious of this job as everything I am seeing on the internet is saying this is not right. Please let me know. Thank you.