Well Drilled - Results

[Pettrix]

My well was drilled today:

Drilling Type = Air Rotary
Well Depth = 505 feet
Static Water Level - 220 feet
Water GPM = 20
Perforated Pipe = 280 feet - 500 feet (20' pipe sections every 20 feet - 100 feet total of perforated PVC pipe)

The well driller said that the 20GPM is "conservative" since they measure the GPM during drilling by taking a bucket and timing how long it takes to fill. He said the well will produce more GPM since the drilling rig is blowing air into the well and this prevents the well from filling normally. He also said that debris can clog the water vains during drilling and that can reduce GPM.

Is the above true?

The well driller claims the only true test is once the well pump is installed one then can get a proper GPM reading.

 

[Egon]

Once the pump is installed the rate you will get is only what the pump can manage under those conditions.

 

[sixdogs]

That's a pretty deep well but good flow. Was your well drilled through rock as I have heard that can temporarily clog. What part of the country are you in?

 

[oosik]

A sustained flow of 20gpm is more than adequate for home use. Drilling can plug the aquifer - that's why many times the well is surged. Surging is designed to remove the sediments, open the water bearing strata & increase flow.

 

[Pettrix]

That's a pretty deep well but good flow. Was your well drilled through rock as I have heard that can temporarily clog. What part of the country are you in?

I am in Northern Arizona (5,000 feet elevation)

 

[Trials]

That's one deep hole! Out here they pump the well completely as they can and then measure the recovery.

How did they locate the water, did they witch for it?

 

[Pettrix]

That's one deep hole! Out here they pump the well completely as they can and then measure the recovery.

How did they locate the water, did they witch for it?

They didn't do that. While drilling with the air rotary they constantly have air pressure blowing into the hole and then a pipe which is dumping the air, water, rock and debris out of the hole.

So at this pipe end they take a bucket and time it on how long it take to fill the bucket. That is the ballpark conservative GPM.

It's not 100% accurate but conservative because the air blasting into the hole is preventing the well area from filling it with water. Think of it as a straw but you are blowing air instead of sucking the water up.

Ideally, like you mentioned, having the well fill up without any back pressure like air blasting into it and then pumping and measuring the refill rate is the best way to measure it.

 

[JPRambo]

Is this a 4 inch well, or a 6 inch well???

 

[Valveman]

Blowing will give you an estimate. But you really can't tell how much a well will make until you test pump it.

 

[Pettrix]

Is this a 4 inch well, or a 6 inch well???

It's a 6.5" bore hole with a 4.5" PVC casing

400 feet is solid PVC while 100 feet is perforated PVC

 

[Pettrix]

Blowing will give you an estimate. But you really can't tell how much a well will make until you test pump it.

So once they install a pump they can test pump it to see how many GPM it makes?

 

[Wild Bill the 2nd]

It's a 6.5" bore hole with a 4.5" PVC casing

400 feet is solid PVC while 100 feet is perforated PVC

The rotary well drilling stuff is all new to me. All I know is cable tool.

I'm just surprised they leave an inch gap around the casing to potentially cave in and drop down to plug the perforated portion. Not sure what the underlying soil and rock conditions are, could very well be fine.

I agree thats you won't be able to get an accurate refill rate till you get your pump installed.

 

[Got2BTru]

As we're just finalizing our #'s for building, it's amazing as I've read several of these well building threads how different the pricing is!

Our specs are ESTIMATED to be as follows:
Drilling & Steel 6" Casing: $42.00 per foot
Bedrock Drilling: $22.00
Drive Shoe: $110.00
Sealed Well Cap: $97.00
State Permit: $65.00
Minimum Charge: $2,500.00 (down payment in advance: $2,500.00)

I think I've seen some of you @ $10 per foot!

 

[Rustyiron]

You got one heck of a well, and unless your planning on watering 100+ head of cattle, you'll have plenty of water for several average households! 1-2 gallons/minute will work fine with 100' of storage (in the hole).

 

[japody]

WOW - 20 GPM!!! That's enough for irrigation. My 5 gpm is enough for my 100+ head of cattle.

 

[Pettrix]

You got one heck of a well, and unless your planning on watering 100+ head of cattle, you'll have plenty of water for several average households! 1-2 gallons/minute will work fine with 100' of storage (in the hole).

No cattle for me. :laughing:

At first I thought 20gpm was low but the more I read comments from people, the more I realize that's good water production.

The well should hold over 100 feet of water.

I found it interesting that they put in five 20' sections of perforated PVC pipe but they alternated them every 20' with a solid PVC pipe. So between 500 feet and 300 feet there is a 20' section of perforated pipe.

 

[CurlyDave]

No cattle for me. :laughing:

At first I thought 20gpm was low but the more I read comments from people, the more I realize that's good water production...

Think about it this way. We built a 4 bedroom house and had an extra-large septic system installed. It rates for 350 gallons per day. That is just a hair under 0.25 gpm. This is all of the water a sizable family needs to live on.

Now irrigation or other outside uses may well increase the amount one draws from a well, but if you can average 0.25 gpm you can live on it.

20 gpm is a magnificent flow rate.

We have 2.5 to 3 gpm, water about 1/4 acre of landscaping and have more than sufficient water.

 

[cat fever]

In my area that would be considered low rates.

My well is 180' deep 6" steel casing, 20' perforated pipe. Pump sits at 156', water is 50' down from wellhead. While drilling the truck was pumping over 100 gallons a minute without the level in the well dropping. I wanted to go down 300' but the driller (trusted friend) said if it was his own well he'd stop at the 180'. He was in a big gravel bed and he said it acts like a filter. I have had no problems of any kind, the well is about 17 years old. The water is crystal clear and cold. Every once in a while there is a slight sulfur smell. Overall I'm very happy with the well.

I would suggest a Y strainer and filter to anyone with a well.

 

[Pettrix]

I got TWO pump options:

A - 3HP Goulds Pump - 13GPM - 3 PHASE - Aquavar 3HP 3 Phase Drive - #10 wire (480 feet), 1.25" SCH 40 GALVANIZED drop pipe (380 feet), 1.25" SCH 140 PVC (100 feet), 8.5 Hydro Pro Tank, misc parts, install, 5-year P&L warranty = $6,700

B - 5HP Goulds Pump - 18GPM - 3 PHASE - Aquavar 5HP 3 Phase Drive - #10 wire (380 feet), #8 wire (100 feet), 1.25" SCH 40 GALVANIZED drop pipe (380 feet), 1.25" SCH 140 PVC (100 feet), 8.5 Hydro Pro Tank, misc parts, install, 5-year P&L warranty = $8,100

Any advice???

 

[LittleBill21]

can some one explain this perforated pipe? i would think it would cause issues with air getting in and stuff, i can see it at the bottom below the pump but i don't understand why it would be above it at all