Georgia Open Loop: Why is a return well prohibited in GA?

Discussion in 'General Discussions' started by Mike Koehler, Oct 4, 2019.

  1. Mike Koehler

    Mike Koehler New Member

    Hi Forum,
    I was planning a 4.5 t geothermal system for our new house in South Georgia. Idea was to use two wells. Pump up from the aquifer, run through the heat pump (UN-treated), then return to the aquifer via an injection well. Since the water would never be in contact with anything else but the inside of my plumbing and the heat pump coil, there would be no contamination whatsoever.

    Doing my research, I found the great State of Georgia explicitly prohibits that. See GA Environmental Protection Department at http://rules.sos.ga.gov/GAC/391-3-6-.13 , Point (16)-(d). Which killed that project.

    Now, can anybody explain to me why other states allow that, and Georgia does not?

    thanks,
    Mike
     
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I have been at happy hour, so bear with me. I followed the link and under the regulations what you need is a class five injection well. Where does it say that it is prohibited? If it has been classified then there is a process for permitting?
    Eric
     
  3. Mike Koehler

    Mike Koehler New Member

    Hi Eric,
    In the regulations, scroll all the way down to point (16) 'Prohibited Wells' and find under sub-point (d): 'Open loop heat pump systems where return water is discharged into a well'. No ifs, ors or buts.

    And, of course, no whys - hence my question.
    thanks,
    Mike
     
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Is it possible for you to do surface discharge? Creek, pond, wetlands? In regard to your original question, the govt. and its agency's often make knee jerk decisions that are not based in reality or backed up by any sane argument. I do not have a clue.
    Eric
     
  5. Mike Koehler

    Mike Koehler New Member

    Surface discharge would be possible, but let's see... hmm... 3gpm/ton x 4.5 x 60min = 810 gph. On avrage 12hrs cooling runtime per fine hot South Georgia day (of which we have on average 250 per year) equals 9,720 gallons per day, or approx. 2.4 million(!) gallons per year of perfectly fine drinking water that I would dump into the marsh. That does not fly at all with my inner Tree Hugger!
    Next idea, closed loop. We would need ~1,800 ft of trenches, 7-8ft deep. Land-wise, that would be possible. But since we are in the marches, we will hit ground water at about 5-6 ft. Which, according to my builder, would make digging very cumbersome and even somewhat unsafe, and therefore too expensive to make any financial sense. Vertical loop? Nobody does that down here. So it is back to the classic air-based HVAC.

    Still, all that whining does not answer my original question to the Forum; so it still stands: What is the reasoning behind that Georgia regulation?

    Any insight would be appreciated!
    Mike
     
  6. wing

    wing Member

    There's no guarantee that the supply well will be in the same geological layer as your disposal well. And there's no guarantee that water to the disposal well will be going into the planned zone due to casing or grout failure.

    So then you have the scenario where the aquifer is being drawn down without replacement, altering the ground water table , aquifer water pressures, your neighbors water wells, ect
     
    Last edited: Oct 6, 2019
  7. Mike Koehler

    Mike Koehler New Member

    Wing: Yep, kind of makes sense... but I still don't know why the geological, grout failure etc scenario is only valid in Georgia... but maybe I should keep my mouth shut, else other states may find it necessary to outlaw Return Wells as well... :D
     
  8. Noobie

    Noobie New Member

    Mike, just curious: why don’t they do vertical loops in GA? We did 5 of them for our geo in MA, and most of it was through ledge, which I would think was as challenging as it gets. Admittedly, I’m not a geologist or driller.
     
  9. Mike Koehler

    Mike Koehler New Member

    The demand just isn't there - so there are no contractors to do that. At least, I did not find any...
     
  10. wing

    wing Member

    Is there a reason that a 5 foot deep trench would not work in your marshy ground ? Sure, not as good as burying eight feet but those wet soil conditions are ideal for heat transfer.

    I have a very similar condition on my horizontal loop - due to high water table I could only get to five or six feet below surface before the ground became too wet. i did compensate by adding more pipe to the design.

    The most important thing is to keep everyone out of the trench, which in wet conditions will tend to cave in. People die every year in trench collapse accidents. Lay your loop pipe on the ground out and back and off to the side of your trench location. The excavator digs the trench starting from the outside manifold location and two people feed the pipe into the trench from the surface, following immediately behind the excavator. After the pipe is in the trench, the excavator then partially backfills to avoid the pipe porpoising. Reverse the excavator ten to fifteen feet and repeat the process. After the loop pipe is installed, complete the backfill with a skid steer.

    I used a three foot bucket and had no problem keeping the out and back pipes on opposite sides of the trench to minimize interference.

    A 350 foot trench with 700 feet of 3/4 inch HDPE pipe was taking about four hours each to install.

    Check out the post 'my most awesome horizontal loop field' for pictures.
     
  11. Mike Koehler

    Mike Koehler New Member

    Wing: Reason #1: Too dangerous - wet trenches are prone to cave. You said it yourself. That leads to reason #2: $$$ for shallower but overlong trenches. Just doesn't make any sense anymore.
     

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