I need to run a variety of electrical and plumbing from my house several hundred feet to the site of my future pool and pool shed. Included in this is geothermal piping, connecting my house geothermal system to the pool heater, and potable water, for a future bathroom off of the pool shed, a hose bib, and for pool filling.
The geothermal system has antifreeze in its closed loop with a min design temperature of 19 degrees Fahrenheit. This is obviously well below freezing.
The potable water pipes, of course, won't be very happy if they freeze.
I don't want to insulate the geothermal pipes, both because of the cost of several hundred feet of insulation and because additional ground contact will improve the performance of the system.
For some general information, I live in NJ and the frost depth by my house is 36". It is customary to bury water pipes at 48", though obviously not bundled with below freezing pipes. My soil is principally rocky clay.
How much separation do I need to prevent the water pipes from freezing? Ideally I want to keep the trench to 16" wide due to the width of the bucket for the trencher to which I have access. Thus I'd prefer to put the geothermal and water lines at different depths in the same trench instead of side by side.
My property is rocky enough (some jackhammering of rocks will probably be involved in this) and the run is long enough that making a second trench is both impractical and too costly.