Well recovery test?

[DStyduhar]

I have been reading about this and it seems pretty straightforward but was wondering if a guy could do this with the currently installed pump or they need a bigger pump to draw down the well more substantially? I guess if you have a high recovery, maybe the average 3/4hp 10gpm type pump might not make a dent in the static level?

Here is how I plan to tes the recovery. Please let me know if this is legit and what I'm missing.

- Have the pump run full time for an hr (more ??)
- Turn off pump
- Use graduated tape to determine static level
- Monitor every minute to find the change in inches/feet per min. From there just calculate from feet or whatever to gallons to determine gpm recovery.

Or can the recovery be derived from basic well specs like pumping level and yield?

Advice on this?

thanks,

Drew

 

[Valveman]

Recovery time is sometimes helpful. But yield and pumping level can be determined by how much the pump is producing from what depth over a period of time.

 

[Sponsor]

 

[DStyduhar]

Is it possible for a homeowner to do their own pump down and recovery test? I can't wrap my head around a way to get my pump to run constantly yet not over pressurize the house. There is a hose bib on the well head, if I opened that (with short hose attached) I wonder if this would bleed off enough water to prevent my worry? Do the pump guys usually just jump the pump? Or jump the contacts in the pressure switch?

 

[Boycedrilling]

as You have surmised, to do a Pump test, you have to force the pump to run continuously. Pump installers might disconnect the Pump from the house by picking a submersible pump up off of the pitless adapter. Another and more practical way for a home owner would be to open enough faucets that the pump would not cycle. If you wanted to make sure that the pump doesn’t cycle, you can jumper the wires in the pressure switch.

However the most important part of flow testing a well is to be able to monitor the water level in the well as you are pumping it at a constant rate. How do you monitor the water level. Well the easiest way is with an ultrasonic water level meter. I have two of them. However they cost around $1,000 each. No probes to go in the well, and results in seconds.
http://www.ravenscorp.com/
http://www.enoscientific.com/

The second option is an electrical wire line. This is a probe that you lower into the well when the probe enters the water, a light and/or buzzer is activated. The wire line has lengths marked on it to determine your depth.
https://www.waterlineusa.com/
You do run the danger of tangling the wireline in the drop pipe. You can get inaccurate reading with both the ultrasonic or eirelinr if you have cascading water. If I’m installing a temporary pump I will usually install a 1” pvc pipe to run the probe in.

A third option is to use an airline. I use either 1/4” air brake tubing or 1/4” galvanized pipe. Usually tubing has to be installed with the pump. Air brake tubing is much more rugged than plain poly tubing. Plain poly tubing is 12-20 cent per foot. Air brake tubing is 35-40 cents per foot in 1,000 ft rolls. I can work a string of 1/4” galvanized pipe into a well if nothing else will work.

 

[DStyduhar]

hmmmm, and you only deal with pitless setups right? No pitless here in NC. I'm trying to think how I could measure the water level while keeping the well cap on. I initially planned to use a bobber or something but it just occurred to me that the pump noise will prob drown out anything I would be able to hear. The pump guy I called has one of those ultrasonic checkers. How accurate are they?

How long do you usually let the pump run for a recovery test?

How long do you let the pump for a pumping level check? Is there a set time ( swear I have seen 4 hrs repeated by more than one person) or do you just run it until the level stops changing?

thanks,

Drew

 

[Boycedrilling]

Most well seals have a 1/2” or 3/4” observation port. The tip of a ravens gate ultrasonic tester will work with that hole. Sometimes I have to pick the Pump up enough to lift the well seal off the casing to get a wire line tester town the well.

4 hours is the standard flow test time for my state. Sometime we will do a 24 this flow test. I’ve got one project coming up that will require a 5 day long flow test, and monitoring of about a dozen existing wells over the course of the 5 days.

I take recovery readings until the well has recovered to its original static water level. This may be anywhere from a matter of minutes to more than 24 hours.

Usually I will run what is called a step test prior to the constant rate test. In a step test I start at one flow rate and run for 20 minutes, then I increase the flow by 50-100% for the next 20 minutes. I will do 3-4 step flow rates, each for 20 minutes. After plotting g the drawdown curve, we will determine the flow rate for the constant rate test.

Plotting. I hand plot all my flow tests on semi-log graph paper. Once you have a curve established on semi-log paper, you can make longer term projections.

 

[Boycedrilling]

 

[Boycedrilling]

In the second plot you can see the change in flow rate at the 20 minute mark.

 

[DStyduhar]

that's awesome, thanks a lot for sharing.

It seems like (sort of reaching here) if a guy knew his pumping level @ max yield (driller should have that info) and pumping level @ a lower gpm (tested with the current pump installed), you could interpolate between them to get a good estimate of pumping levels.

 

[Boycedrilling]

Yes. Usually it can be distilled down to gpm per foot of drawdown.

 

[Boycedrilling]

I’ve had as much as 3000 gpm per foot of drawdown all the way down to just a fraction of a gallon mere minute per foot of drawdown.