Thermal degredation

Arnold E. Clubine

Any experience with geothermal vertical bore holes causing heaving of asphalt parking lot?

Zman

What climate?
I could see the top of the well being resistant to frost heaving and the surrounding lot moving seasonally.

JUGHNE

Was the parking lot a new install after boring or patchwork to do the drilling?

Mark Eatherton

Frost heave or bentonite (grouting) heave?

What kind of temperatures are you seeing from the VBH loopfield?

Also, the PE tubing does have significant coefficients of expansion...

Jamie Hall

Don't know about geothermal wells -- but for either water supply or environmental monitoring wells, if the well is to terminate at or above the surface in any paving, the well casing itself must be isolated from the pavement with an outer sleeve, not fixed to the casing. And, of course, any drop pipe inside the casing is isolated from the casing -- vertical restraint at the pitless adapter (if used -- or from the casing itself, but only at the top) and horizontal restraint (centring or anti-torque spiders) as required but no other vertical restraint.

I have found that over time, at least in a climate with frost or freezing, if you don't do that the paving will jack itself up the casing. Most annoying.

GroundUp

If the lot was paved shortly after the wells were bored and you are in heavy soil, I can definitely see it. I'm in very heavy clay here, and any recent excavation of clay in the surrounding area that is backfilled with the excavated clay is a terrible heaving mess.

Gordy

First you have to determine if the well heaved, or did the parking lot settle. As @Jamie Hall pointed out hopefully there was isolation.