Hello,

This is my first posted question.  I am in the process of installing a 4 ton GSHP using a horizontal 36" pitch slinky in 4 x 100' trench spaced at 12' at 6' depth for a GHEX.  During trenching of the first trench we encountered rock at 50'.  At the 100' mark, the trench was only 2' deep.   After digging more test trenches, we decided to relocated the trench layout 90 degrees starting from were we first encounted rock.   

The first new 6' trench encounted two spots were the rock rises to 4' depth mark about 10'  in length.   The next trench encounted two spots were the rock rises to 5' depth for about 8' of length.  The third trench just scraped the top of the rock and the fourth trench was clear all the way through.

I am looking at jack hammering out as much rock as possible.   The questions is what should I bed the trench with to protect my PE pipe?  Should I use 4"-6" of red clay which was excavated or use rock dust or sand?

Next question is I am also going to install dripper/soaking pipe above the loops in the trench in order to keep the clay from drying out.   Cheap insurance since we just had a very dry summer here this year.  The clay soil was very dry down at the 4' level when I dug a test trench back in August. 

I talked to one irrigation supply house about using their 1/2" PE drilled dripper pipe.  I was told that the pipe should not buried more than 6" below the surface.   I was also the first person they talked to about using the pipe for a GHEX.

What are other installers doing to maintain soil moisture?   I also was thinking of running 4" drain pipe from the two downspouts out to the loop field instead.