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Source and injection well proximity

Last Post 26 Dec 2009 09:51 AM by Down2Earth Geothermal. 5 Replies.

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byrdman73

New Member

Posts:2

23 Dec 2009 06:02 PM
I have (2) 2.5 ton geothermal heat pumps and plans for an additional 1 ton. My existing well is bored (24" diameter) and 30 ft deep with a water table at ~15 feet. The existing well is rated at 2gpm so its being a real trooper in keeping up with my demand. I don't think it will make it through the next summer. So I'm going to have another well drilled for use as a source and use the old well as the injection dump. The new well will be good for 10+gpm. My question is.... How close can I put the source well to the injection well? I only have an acre to play with and the septic drain field takes up half.

geotek

Basic Member

Posts:154

23 Dec 2009 06:25 PM
Minimum distance is 50 ft. though local codes prevail.

engineer

Veteran Member

Posts:2749

23 Dec 2009 10:57 PM
That's a big drainfield! 50' should do it, but with six tons on the system a bit more distance could help, especially since your wells are fairly shallow. If your new source well is substantially deeper than the 30' injection well, that may provide some useful vertical separation.

Curt Kinder <br><br> The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>

waterpirate User is Offline

Basic Member

Posts:467

24 Dec 2009 05:37 AM
I am going out on a limb here, is your new well going to be bored to aprox. the same depth as existing? Or are you going to have the new well drilled to a greater depth? If the new well is to be drilled to depth, your old well is mearly a french drain into the surface water, and amount of seperation will not really matter. If your new well is to be bored like the existing one, you are aproaching a slippery slope in regard to production long term and seperation distance.

Eric Sackett<br>www.weberwelldrilling.com<br >Visit our Geothermal Resource Center!

byrdman73

New Member

Posts:2

24 Dec 2009 08:34 AM
50 feet of separation may be hard to achieve. My lot is on a culdesac so its wedge shaped with the drain field taking up most of the prime space in the back and the well limited to the smaller portion in the front yard. The new well will be 75-100 feet deep. The deeper the better, but I am limited by cost. By the reponse I've gotten, it seems that 50feet is a guideline but that there is quite a bit of gray area depending on conditions. I'm in a place called Willow Spring, and coincidentally I have a spring that pops up in the backyard after days of heavy rain and a swamp/creek at the far back of my property. I'm sure that there is no shortage of water to be had, I just don't want to have the 2 wells so close that I'm recycling the same body of water over and over. If vertical separation can be combined with horizontal separation, I think I can achieve 50'

Down2Earth Geothermal User is Offline

New Member

Posts:59

26 Dec 2009 09:51 AM
In terms of separation distance, in addition to the vertical separation suggested by Eric, it can also help if you can locate the new supply well so it is upgradient from the return well in terms of the local groundwater flow. This way your injected water is dissipated by the normal flow. Shallow groundwater flow often follows surface topography which may give you some indication. Also, you want to make sure your current supply well can accept additional flow in it's new role as an injection well. Wells can often produce more water as an extraction well than an injection well. -Adam