The location of our two boreholes is right where we might put a garage.  My contractor said the boreholes were several feet down in the ground, but I wasn't there to see any of that happening. 

Any thoughts?  Bad idea in case of future problems?

What kind of loop do you have again? If I recall correctly, it was not as common as others, right?

We build entire houses over boreholes on tiny beachfront lots

Just 2 vertical holes with double-pipes in each. (300 feet deep x 4 loops (2-per hole))

What was the loop material again? Just curious. :-)

Oh, it's called Raupex, it's a pex made by Rehau. 1" diameter. I think it's officially called "PEXa"
http://na.rehau.com/construction/renewable.energy/geothermal.ground.loop.heat.exchange/raugeo.collect.shtml

There's should ever be a need to access the boreholes, right?

You should check with Rehau and get their OK.

Bergy

Posted By stuart.wyss on 16 Jul 2010 10:26 AM


There's should ever be a need to access the boreholes, right?

Never say never,  but it is a calculated risk many people take.

BUMP We're going ahead (finally) with plans to build the garage and yes, it can only be right over the boreholes. The drillers assured me the pipes are at least 4 feet down. The garage foundation perimeter is to be 3 feet down. Fingers crossed nothing gets snagged by the construction equipment. 2 vertical boreholes, trenched to the house.

It would be interesting to know if the lack of rainwater eventually effects the thermal conductivity, at least for the upper portion.

@ jonr
Don't say things like that!! I don't wanna be a test-case!!! But I do have a year's worth of WEL data for some comparisons of EWT and delta T on the loop.
It's not a big garage and it's detached. Chances are a lot of water will be able to migrate down from the surrounding grassy areas.

Probably, although you could put in a soaker output (or floor drains right above the boreholes) just in case. With evaporation to the surface blocked, I suspect that it would take very few gallons to keep it moist.

Don't worry about. Vertical loops are not very much at all affected by rainwater. you usually have much more saturated ground down deep, that is one of the reasons you need lesser pipe than in horizontal loops.

If you are above ground water level (say at 50' with water at 200'), where does the water that is saturating/dampening the soil come from?

Rain Water will migrate down and stay in the ground. Capillary action helps contain the water. It also does not evaporate. Nor did anyone say that it has to be saturated.

I wouldnt be concerned about rainwater losses. Vertical Bores barely get any of their conducting capacity in the first 10 -20 feet. To calculate this loss would be trivial.

Only Real danger is the guy with the backhoe! Once he is gone you should be fine.

In my area (DFW) large school districts are moving to geo.  Hundreds of boreholes, per school are drilled, placed deliberately where parking lots are or will be placed.  I'd estimate at least 80 - 85% of these school district boreholes are at locations with pavement on top of them.

As an example of a concrete covered borehole field, I'm working an energy reduction project now, for an indoor sports facility, that has 17 geo package units hanging from the ceiling, all connected to one big water loop.  All of the boreholes are under the concrete parking lot.

Best regards,

Bill

The horsefeather project, 28 heatpumps, the entire common loopfield is below a 3000 sqf parking lot.
The Welserver is not fully done yet, but you get the idea.


http://welserver.com/WEL0714/


http://horsefeathersmarket.com/

Doc, nice job!

Best regards,

Bill

thanks for the pad on the back