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Anyone heard of such a thing?
I heard of this procedure being done by a homeowner (Blue Ridge Mountains West Virginia)who was having slow recovery in his well. He ordered a water truck filled to capacity and pulled it right up to his well head. Seems he dumped the entire truck of water down the shaft as fast as it would take it and produced a backflush condition. The story goes he could taste the chlorine in the water deposited by the truck for about three or four days. The well has performed flawlessly since with no lack of supply or any sediment as it was prior to his procedure.
Seems like a cheap fix to a real headache of a problem. I could use some help with my own well and was wondering if anyone has heard of this type of remedy and could you endorse it.
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Yep! We call it "making" a well. Pretty common thing to do. Supposed to clean out a pocket around the water intake. Whatever, several times I've seen it really "make" a hole in the ground a useable well.
*I was with Geraghty & Miller (oldest groundwater consulting firm in the country) for 7 years. Two senior guys had taken a few years off and made big bucks reconditioning agricultural wells. A farmer's well, once 200 gpm would be down to 100 gpm and the farmer thinks he's going to buy a new well for $20,000. They'd ask him, how much is it worth to you if we get it back to 150 gpm? If we get it back to 200 gpm? And wrote a contract basically for $ per gpm. They would consistently get the well to test at well more than it did orginally (like 300-350 gpm in this example) because 1) they knew the theory and practice of well development and 2) virtually all wells are not properly developed in the first place.A little hydrogeology: When a well is drilled, the "formation" (soil matrix) is damaged by the friction, motion and vibration of the drill and/or drilling fluids. The face of the formation gets caked up with dense, compacted material like what that really hard, glazed stuff that falls off a dozer's tracks. Many wells, if drilled but not developed, are only 10% efficient (a drawdown of 10 feet in the well casing only drawdown the water table 1 foot) resulting in one tenth the theoretical maximum flowrate.There are many ways to remove that caked-on material and restore some of the original permeability. Most involve passing water or air through the well screen quickly and removing any fines that end up in the well. Explosives or extremely high pressure water or air are occasionally used to fracture or hydro-fract the formation.As described, you can simply backflush the well at a high pressure and flow. This is especially good for removing fines that have piled up on the sand pack or casing.High, intermittent pumping rates will bring fines in the casing. This requires a larger pump than the one you will you use long term because it needs to create very high flow rates for short periods of time. It also requires a pump you don't care about to remove the fines from the well casing.A plunger of sorts can be physically run up and down the casing to create pressure and vacuum alternately and wash fines from the face of the formation (i.e. "block & surge").There are many other techniques including ways to kill bacteria that may be clogging things up. Fletcher Driscoll's "Groundwater and Wells" is an excellent $62 reference on drilling, developing and maintaining wells. Available at amazon.com -David
*David, When you talk about the face of the well getting caked up... does this happen in wells drilled with a cable tool also? If so, does it happen to the same extent as in a well drilled with a rotary drill?
*David, When you talk about the face of the well getting caked up... does this happen in wells drilled with a cable tool also? If so, does it happen to the same extent as in a well drilled with a rotary rig?
*Mike: yes, cable tool and hollow-stem augers both damage the leading edge of formation. Mud-rotary leaves everything coated with drilling mud which is very fine, mucky stuff (but can be removed during well development). Air-rotary probably does the least formation damage but it is such a noisy, expensive way to drill a hole, it is more commonly used to drill rock. Smartest driller I knew considered cable tool to be the most versatile, under-appreciated rig type (as long as you're patient). -David
*They do the same thing to oil wells. It's called fracturing. The equipment is amazing. They manifold 6 or 8 or more 1,000 HP Cat diesels driving triplex pumps (6" cylinders) and force a mixture like sand in jello down the well at pressures around 30,000 psi.Makes a hell of a roar...sometimes continues for several hours. It usually increases production from the well.
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Anyone heard of such a thing?
I heard of this procedure being done by a homeowner (Blue Ridge Mountains West Virginia)who was having slow recovery in his well. He ordered a water truck filled to capacity and pulled it right up to his well head. Seems he dumped the entire truck of water down the shaft as fast as it would take it and produced a backflush condition. The story goes he could taste the chlorine in the water deposited by the truck for about three or four days. The well has performed flawlessly since with no lack of supply or any sediment as it was prior to his procedure.
Seems like a cheap fix to a real headache of a problem. I could use some help with my own well and was wondering if anyone has heard of this type of remedy and could you endorse it.