Greetings,
I was wondering if anyone here has experience digging trenches for *vertical* slinkies.

I have seen quotes for drilling 600' of borehole, and I have had experts come and say
it's too hard to dig trenches, and there's no room for the dirt,
but I saw how they dug my basement, and I thought
of a way to put in trenches without needing quite so much space to pile up dirt.

I have a 100' driveway.  The back lot is 50' wide.
I have seen articles about 8' deep trenches holding 2 slinkies.
These are my background.

What I thought to ask for - possibly from the sub who dug my basement
(via the existing general contractor) -
1. dig a 50' trench across the back lot.
Stand up a slinky so it wraps around the end of the trench and returns
to the entry to the building.
2. do the same for the last 50' of the driveway, backfilling the first trench.
3. Do the same for the front 50' of the driveway, backfilling the second.
4. backfill the third trench with the dirt from the first.

All these trenches will start/end from near the same spot, where the
two 6" HDPE entries have been buried already - lead is about 10'

My question is, is "dropping in" the prepared coils a big enough
job that it would be excessively wasteful to do it while the backhoe
is waiting?   (just for reference, on Sunday, I installed PEX radiant tubing
in a ceiling that happened to be opened for construction :-)
Wiring and plumbing for MultiAquas is in place.

Each of the trenches is 50' long, presumably 4' wide x 8' deep. 
The back yard (for dirt storage) is about 10' wide x 50'
and a second area about 6' wide x 50'.
There is also an empty carport 16 x 22' - but that would require
men with shovels or a bobcat-like vehicle.

My builder thinks they would have to take dirt away ($$) and
bring it back ($$$) - though I wouldn't want it back.
I would have them make it level, and buy topsoil/mulch instead
(or build a compost hill - the season has begun :-).

I know I haven't given all the details, not asking for a guarantee,
just any heads-up.

I heard a saying -
An engineer who says something can be done is probably right.
An engineer who says something can't be done, is probably wrong.
I am not naming names, but I know a few of the latter.

Thanks alot
Seth

PS I also would like to know about grout in horizontal loops.
I have seen a lot about vertical loops.
Also, does the grout cure into a concrete?   or does
it remain granular?  

Sure, vertical slinkys can be done. If loops are prepared before excavating, there is not a lot of down time for the excavator. It is more difficult to bury a vertical due to more likely crush factor. ie; backfill will be slower. To stack them and get the desired result, you will have to factor and size lengths according to soil type, spacing of loops, soils temps in your area, run fraction, and of course the load calculations. Then there is a multiplier for how close the loops are with respect to each other. Desired entering/leaving water temps would also be required to calculate. All contribute to the overall COP of the system. There is another saying... You get what you pay for. I am sure you will get a lot of free advice and opinions here. Some of it will be good.

You could backfill with sand. And/or use a chain trencher.

Grout is intended to make a good thermal connection between vertical loops and surrounding soil and prevent contamination of aquifers. It is not required for horizontal loops.

The loops you describe don't sound like they'll add up to much. Your design needs to start with the home's requirements from which equipment and loops can be sized.
j

how many ton unit do you need. 3 50' lenghts is not alot .