Do open loop geo systems often leak oil through the heat exchanger and contaminate the water passing through?  If so, then I understand why one has to be careful in returning the used water to a well.

Would the chances be less for contaminating deep ground water if the used water was returned to a pond?  Is this oil such that a sheen would be noticeable on the pond surface?

Do geo systems give any indications that refrigerant oil has leaked?

These questions may have been answered in the past but my search did not help me much.

Speaking from experience (i.e. homeowner with open loop geo) I have never seen a sheen on my pond (and certainly would be very alarmed if there ever was) and I have been running my system for about 3yrs now. Correct me (anyone) if I wrong here but don't believe the amount of refrigerent is all that great relative to the amount of water that flows thru these systems. However, if you were to somehow loose refrigerent into the water discharge (highly unlikely) you would most certainly notice it (delta t would become very small).

Agreed leaks are rare and usually cased by low PH or solids (sand) erosion in coax. Typical unit holds less than 2 quarts of Polyoester oil (synthetic).

This was suggested to you by a closed loopadvocate and has no foundation in reality.
If you want to keep consistant with the anti arguments, the leak of CFCs into the atmospere is more harmul than oil in the ground.....
j

Please also keep in mind that even though we are in 2010, all of our responses to polution are the same as they were in 1900. "dilution is the solution for polution". What would be the amount of oil lost from the unit prior to unit lockout or failure? That amount would be introduced into what volume of the aquifer? This is also the knee jerk argument against dx which is simmilarly unfounded under scrutiny.
Eric

What's amusing about this is if we compared it to a closed loop vertical with methyl for instance you have many times the available contaminants kept at bay by a heat exchanger wall.
j

No wurries.

Methanol and ethanol biodegrade rapidly in soil or groundwater.

Don't know about p-glycol -- but I can't figure out why anyone
would choose p-glycol for a geo loop application. ...why?

Posted By Looby on 23 Aug 2010 01:27 PM
No wurries.

Methanol and ethanol biodegrade rapidly in soil or groundwater.

Don't know about p-glycol -- but I can't figure out why anyone
would choose p-glycol for a geo loop application. ...why?

Great question.
There is movement afoot to suggest p-glycol is more enviro friendly. It is of course not the most geo friendly (harder to pump, poorer heat transfer...poorer COPs meaning more coal smoke belching at the electric co.). I expect it may be the only approved antifreeze round here in the next 10 years.
J

Posted By joe.ami on 23 Aug 2010 08:14 PM
There is movement afoot to suggest p-glycol is more enviro friendly.

There's no way that p-glycol could be more eco-friendly or less toxic than ethanol
(he types, while joyfully sipping from a wee jar of 430,000 ppm highland ethanol).

...so, is that movement the great sharia conspiracy? ...or has Carrie Nation returned?

Looby

Alas, my wee jar of the moment runs to only 80,000 PPM, but it is mostly excellently hopped India Pale Ale.

I further guarantee it will have been divested of all those PPMs before I return it to the local aquifer at sunrise on the morrow.

Posted By Looby on 23 Aug 2010 10:02 PM

Posted By joe.ami on 23 Aug 2010 08:14 PM
There is movement afoot to suggest p-glycol is more enviro friendly.

There's no way that p-glycol could be more eco-friendly or less toxic than ethanol 

As is often the case, legislators can be persuaded more by hype than science. Stay tuned......
J

Gentlemen - this is a topic I have struggled with for many years. I am not so concerned about the small amounts of coolant etc that might escape the system but rather the chance of some of the following. Mixing aquifers. Introducing e-coli, legionnaires disease etc. to a potable water aquifer. Transferring water from an already contaminated aquifer to a potable aquifer. Also I would be concerned about discharging (wasting) potable water to a pond at a time when many people are worried about enough drinking water. Also with open discharge, do we calculate the net effect of that discharge? Is there a chance of causing soil salinity? Will the extra hydraulic pressure cause a seep some distance away that will bring soil salts to the surface and ruin someone's cropland? As early as 1974 we used simple heat pumps to extract heat from one well and discharge it into another. This is something that I myself would not do today. It is not my intent to criticize anyone but rather to open the discussion on contaminant possibilities.

FBBP
You seem to have some inteligent input and are drawing on an extensive background of experiance? Out yourself by filling out your info page and if you are a proffesional how about a web address or company bio?
Eric

Posted By FBBP on 27 Aug 2010 11:54 PM
Gentlemen - this is a topic I have struggled with for many years.
1) Mixing aquifers.
2) Introducing e-coli, legionnaires disease etc. to a potable water aquifer.
3) Transferring water from an already contaminated aquifer to a potable aquifer.
4) Also I would be concerned about discharging (wasting) potable water to a pond at a time when many people are worried about enough drinking water.
5) Also with open discharge, do we calculate the net effect of that discharge? Is there a chance of causing soil salinity? Will the extra hydraulic pressure cause a seep some distance away that will bring soil salts to the surface and ruin someone's cropland?
6) As early as 1974 we used simple heat pumps to extract heat from one well and discharge it into another. This is something that I myself would not do today. It is not my intent to criticize anyone but rather to open the discussion on contaminant possibilities.

Thoughtful response and fair summation of some folk's concerns.
My thoughts to your points:
1) Not really a geo exclusive possibility as mixing aquifers can occur whenever they are penetrated, be it geo drilling (open or closed loop) or water well drilling, mining etc. In my home state of MI, the DEQ requires licensed well drillers be involved in bores deeper than 14' (ish). Permits are required and protocols enforced.
2) In the case of return, injection or standing column wells are there many cases of geothermal heat pumps introducing bacteria during the process of adding or removing heat from the water? I am unaware of any, perhaps someone has some cases they can cite?
3) This again would fall under DEQ in my area, if folks follow drilling rules it can't happen. If they don't follow the rules......well I guess this again isn't limited to geo systems.
4) Many suggest that water does not go away when discharged into a pond but is returned to mother nature for recycle. This argument is common enough that a fella on another forum suggested he didn't want to "waste" water to temporarily operate his system (as open loop) prior to excavation. It turned out his city water supply came from the Mississippi river. Ground dispersal or discharge to a storm drain would have returned the water where? You guessed it, the Mississippi river. While paying for city water may have been more expensive than electric space heaters and water "treatment" may have been wasted, the water cleary wouldn't have been.
5) I live an area rife with artesian wells. Water literally bubbles out of the ground. In some areas anti open loop sentiment prohibits us from taking the energy out of that water and dispersing it where it was headed to begin with.
These areas are often adjacent to cultivated farm plots. Doesn't mean salinity couldn't be a concern somewhere, but it is not a concern everywhere.
6) As early as the 1890's we have been heating with underground hot springs and using pump and dumps since the late 1940's. While again I haven't broken my neck trying to find a case, I'm still not aware of bacterial introduction to an aquifer by geo. I have heard of harm to local eco system by fuel oil spills however. 

Lest we forget, gas and oil must be drilled for to support other heating systems. A recent glaring example.....
(promised myself I wouldn't go there).
We all want to be careful in such a discussion not to cite the obscure to suggest a norm.
j

FBBP
You seem to have some inteligent input and are drawing on an extensive background of experiance? Out yourself by filling out your info page and if you are a proffesional how about a web address or company bio?
Eric

Just a dumb G.C. with too many years at the school of hard knocks! We have run a couple of construction companies out of the Calgary Alberta area for the past 30 years that provide Design and Building services for the light commercial and residential markets. I have had the privilege of working with some very knowledgeable trades and consultants over the years and as my passion is for putting together different elements for the best end result I try to retain as much as I can. Some of my questions are because I see to often a jumping on the band wagon approach without due diligence. What might be the best solution in one area is not necessarily the best in another. Also there is really no system or way of living that has no impact. Some times we know that the system we are recommending is not perfect but believe it to be the best at that time and place. As this is a green forum (much more informative than most) we need to properly assess our technology and recognize it limitations even if we believe it to be the best available. Here in Alberta (as in many other areas) there is a huge push for wind power. The people pushing the mills are not willing to look at their downside so the is very little open discussion that could benefit all. The same with geo thermal. Too many people are instant experts and the mouth far exceeds there true knowledge.
Presently working on my own house, two storey ICF, conventional roof with R60 insul. Solar collectors to thermal mass for heating. Will probably tie in a compressor to reclaim t.m. storage after it drops below 80º. A few bugs yet but thats half the fun right?
I better quit, I'm babble again and way of topic! Sorry.

My thoughts to your points:
1) Not really a geo exclusive possibility as mixing aquifers can occur whenever they are penetrated, be it geo drilling (open or closed loop) or water well drilling, mining etc. In my home state of MI, the DEQ requires licensed well drillers be involved in bores deeper than 14' (ish). Permits are required and protocols enforced.
2) In the case of return, injection or standing column wells are there many cases of geothermal heat pumps introducing bacteria during the process of adding or removing heat from the water? I am unaware of any, perhaps someone has some cases they can cite?
3) This again would fall under DEQ in my area, if folks follow drilling rules it can't happen. If they don't follow the rules......well I guess this again isn't limited to geo systems.
4) Many suggest that water does not go away when discharged into a pond but is returned to mother nature for recycle. This argument is common enough that a fella on another forum suggested he didn't want to "waste" water to temporarily operate his system (as open loop) prior to excavation. It turned out his city water supply came from the Mississippi river. Ground dispersal or discharge to a storm drain would have returned the water where? You guessed it, the Mississippi river. While paying for city water may have been more expensive than electric space heaters and water "treatment" may have been wasted, the water cleary wouldn't have been.
5) I live an area rife with artesian wells. Water literally bubbles out of the ground. In some areas anti open loop sentiment prohibits us from taking the energy out of that water and dispersing it where it was headed to begin with.
These areas are often adjacent to cultivated farm plots. Doesn't mean salinity couldn't be a concern somewhere, but it is not a concern everywhere.
6) As early as the 1890's we have been heating with underground hot springs and using pump and dumps since the late 1940's. While again I haven't broken my neck trying to find a case, I'm still not aware of bacterial introduction to an aquifer by geo. I have heard of harm to local eco system by fuel oil spills however. 

1) I agree. I don't believe there is any significant risk with a closed loop properly grouted bore. Don't think we should blame the technology just because of poor workmanship. How ever on an open returning to a different well even if the is no contamination you could still mix aquifers.
2) I know of one in another province but that is not enough to ban the practice. Still I think for myself the risk factor is to high.
3) Even if both wells are properly installed, one could become contaminated, which would immediately contaminates the other.
4) That would suggest a City could use up all the water in the river because it gets back there anyway ;-). How much of the water of the Grand Canyon is left after irrigation etc? The reduced river flow has a tremendous impact on the ecosystem (no spawning, reduced bird life etc.). However pumping from an aquifer has a much higher impact as the water rarely returns to the aquifer it came from. Most aquifers are recharge miles from where the are depleted. In many areas industrial pumping and irrigation from aquifers have depleted them to the point there is no residential water or because the flow rate and pressure has been dramatically altered the waters chemical characteristics change.
5) Certainly salination would occur every where but that is why proper site evaluation is so important. In your case, it would occur anyway whether or not it was run through your compressor. However you must also acknowledge that you are not putting the water back exactly like you found it. It is going back several degrees colder. Do you know what the impact of that is? I bet many people don't give it a thought.
6) There is many case of contamination in any water usage. Why would this industry be immune? The truth is most well suffer some contamination every day however nature can handle a lot more than some give it credit for.

No of the above is to say you should not use open discharge but I would suggest people spend more time doing proper site evaluations and that "someone" draw up guidelines for doing them. You can be quite sure that at the first major contamination, many of us working in the geo-therm field will be legislated out of work!

ps stop dumping on poor BP! They just want their life back;-)