WSHP: Supply well and return well spacing?
 

Hello. I've been drilling away for groundwater to supply a water-source heat pump. Frankly, I don't really know what I'm doing, aside from a significant amount of reading online.

I'm at 25' right now, and FINALLY drilling is smooth-sailing, going through white coarse sand... one hell of a lot easier than the red clay so prominent here in NC. I ended the day yesterday out of pipe (and out of daylight) just as the drilling got really easy.

I'm using the drillyourownwell.com technique, which is basically using PVC as drill pipe, with a steel nipple as a bit, and a trash pump to flow a lot of water down the pipe.

I will be aiming to "pump and dump." But, I don't know how far I should locate the return well from the source well. I surely don't want a short-circuit, but I also don't want to have to trench really far away. Are there any guidelines for this sort of thing? Similarly, would it be a better idea to use multiple shorter wells for the return, instead of a single?

All thoughts are welcomed!

Currently 41 feet...

Here's your EPA road map:
https://www.epa.gov/sites/production...returnflow.pdf

NC is not a particularly friendly state with regard to DIY pump and dump wells...

Hmm, I'm reading through that, as well as the NC permitting requirements. It doesn't look too bad. I see on the permit application that they are wanting the drilling contractor's information; we'll see if they allow individuals to do their own.

Thanks for pointing this out; I didn't think it'd be an issue with a shallow well, but apparently that's not the case.

I had a well drilled in SC about 20 years ago. That coarse white sand is what my well driller called sugar sand. It is where you will usually get your best water.

The driller broke through the red clay and into sugar sand at 33ft. He stopped when he hit hard stuff at 73ft. Thus I had a 40ft stand of water, actually about 48ft since the water pushed up to within 25ft of the surface. With a 1/2HP submersible I was getting better than 20GPM and was never able to pump it dry. That was a six inch pipe though.

You might want to stop and test your water level.

I would be less concerned about the distance between wells than the possibility of contaminating the aquifer. That is why some states prohibit pump and dump.

Still going...
 

We hit 60' today.

I have 23 feet of well screen fabricated. We went through a lot of sand a while back, but it has been nothing but fine silt and clay since.

The plan is to keep going, hoping there's some more sand down there somewhere. But, damn it, I think the well screen will be below the first sand level. :(

We'll be cementing the top of the well to reduce the chance of any contamination. As far as the return water goes, it appears that injection wells are the biggest area of concern for contamination. So, I may just try to go the French-drain style way of returning the water to the ground. I just don't know yet; I have to make sure there will even BE water first! :)

Slippy,

Have you considered a pond for the outlet water? That way, water slowly filters into the aquifer and you have a water supply that can be used in the case of a fire. Many insurance companies substantially lower home insurance rates in rural areas if you have a pond.

Steve

Thanks, but no room.

Would love to know how you fabricated the screen. Sounds interesting.
Congratulations on 60'.

Well, we have a problem.

Shortly after adding some kitty litter (bentonite) to help remove cuttings, our pump ran out of gas. I rushed to partially fill the tank, and in those down 30 seconds, we went from smooth-as-silk movement to stuck-like-glue.

A chain hoist will give us about 1/2" of total movement, under great strain. Release tension, pipe goes right back. It almost feels like the PVC is stretching, if that is even possible.

We have used a new 3/4" "rescue pipe" and have cleared out the center of the drill pipe nearly to the bottom (set screws are located about 6" from bottom). We removed the rescue pipe, and have reinserted it right beside the drill pipe. All day yesterday we were removing very, very, very fine silt all day, and were battling getting the rescue pipe stuck. Seeing nothing coming out of any size (not even a grain of sand), we tried pumping FROM the rescue pipe, but that was very problematic. It was hard to get/keep the pump primed, suction was low, and on one insertion we got a glob of clay which plugged the pipe.

We have gone down to within 2 feet of the bottom of the drill pipe with the rescue pipe, and I guess will take it all the way down on Monday to see if that will help.

I'm toying with driving an hour away to fetch some REAL drilling fluid stuff (thinking a polymer-based, and maybe a flocculant), as well as perhaps going AROUND the 1-1/2" drill pipe with a new 3" drill pipe. If that goes, then it sure would make the well screen insertion go easily... so long as we don't stick the 3".

Yes, two days of struggling. I perhaps should have just abandoned and moved over a foot.

What particulates we are removing, when settled, feel like the mud at the bottom of a lake. Very, very "powdery." When you squeeze a handful of it to get most of the water out, it feels like modeling clay. Giving a ball of it the 1-meter drop test, it deforms into a pancake, with no breakage.

If anyone has any thoughts on unsticking my drill pipe, I'm all ears!