# Rotary well drilling questions



## Protech (Sep 22, 2008)

So I'm having a well drilled for irrigation.
Some things don't make sense to me though. The drilling contractor says he needs to drill 200' yet he is only putting in 80' of 4" casing. Then only 60' of 1.25" pipe down to the submersible pump.

What good is the extra 120' of drilling going to do past the end of the casing? Seems to me the guy is just doing the extra drilling to pad the bill since it's by the foot. I don't see how boring deeper then the casing is advantageous. The water table is 30' down. The pump is going to be sitting 30' deeper then that. Won't everything below the casing just collapse in anyway?

Any drilling pros wanna weigh in on this?

Thanks


----------



## tim666 (Mar 11, 2014)

I am not a drilling pro but in Nova Scotia they have to install minimum 20 feet of casing. The amount of casing depends on where they hit bedrock and the hole will remain intact. The area where I live you would be lucky to make it 4 feet before you hit bedrock so most cases it is just the 20 feet of casing. Further inland I have heard of up to 200 feet of casing. However keeping the pump 140 feet off the bottom seems strange but I don't know what ground conditions they may have encountered in your area. We have had to install pumps 50 feet from the bottom because they encountered a lot of sand


----------



## paultheplumber1 (May 1, 2014)

Tim is correct on the casing. Only need it to get to the bedrock. Around here all wells use a 6" casing. Most submersable pumps are 4" in diameter. If a piece of ledge or rock ever shifts your never gonna get that pump back up. Also an actual driller has to go down deeper to create a res of water because the drill bit will plug off some of the veins as it pulls up drillings.


----------



## AWWGH (May 2, 2011)

I'm a licensed well driller so I hope this helps. In our area we drill 6" wells into bedrock, minimum 20 ft of casing and a minimum of 10ft of casing into bedrock. Once in bedrock we drill to water. Typically we leave our pumps 20-40 feet off the bottom on the hole, but when the driller is set up on the hole he knows where the water is clean and where it's dirty. 

Do yourself a favor and trust the driller if he says to leave the pump up in the hole. The water supply could be from the bottom of the well even though you have a high water static, this is hydrostatic pressure- some wells even run over the top with hundreds of feet of casing in the well. We keep pumps up on the well to help with sediment if it's heavy towards the bottom.

What is the well yield? Do you have. Well drilling completion report?

Im third generation well driller and drilling is an art. You can teach anyone to run the machine, but it takes experience to understand what's going on hundreds of feet in the ground. If he says keep the pump back in the well I would trust him rather than think he's trying to screw you.


----------



## rjbphd (Feb 5, 2010)

AWWGH said:


> I'm a licensed well driller so I hope this helps. In our area we drill 6" wells into bedrock, minimum 20 ft of casing and a minimum of 10ft of casing into bedrock. Once in bedrock we drill to water. Typically we leave our pumps 20-40 feet off the bottom on the hole, but when the driller is set up on the hole he knows where the water is clean and where it's dirty.
> 
> Do yourself a favor and trust the driller if he says to leave the pump up in the hole. The water supply could be from the bottom of the well even though you have a high water static, this is hydrostatic pressure- some wells even run over the top with hundreds of feet of casing in the well. We keep pumps up on the well to help with sediment if it's heavy towards the bottom.
> 
> ...


Good to see u here again, AAWGH... when I replace well pump from old well here.. I always blow it out... I sleep better knowily the new pump inside debris free well..


----------



## mytxplumber (Jul 28, 2013)

I had my drillers license also I finally dropped it after a lot of years. You can usually look at the well logs for your area online. The logs will show you how deep the wells are in your area. I am with the other Driller here. Your well will be cased until you hit bedrock then they usually case the top 10 ft. The pump needs to sit up high in the well to keep trash out of the pump and so you get better quality water. Good Luck


----------



## Protech (Sep 22, 2008)

I have never drilled a single well. I have serviced many in my area. There is typically 30-40 feet of sand and then you hit the karst limestone that Florida is famous for. That is water bearing. Now the static water level around here is usually just below the sand layer (about 30 feet down). Pretty much every submersible pump I've pulled was 60 feet down. I've never measured how deep the hole is below the pumps. The drop pipe is always rusty 30' down. So if the static water level is 30 feet down and the pump is 60 feet down why drill much deeper then that? It can only pull water from as deep as the casing is. Past the casing the karst is VERY porous. If the dynamic water level was to drop to the end of the casing then it would just pull air through the porous karst and the pump would run dry.

I don't just trust the contractor as he bills by the foot and his quote was the highest I've heard of by far. Now I don't mind paying more to have something done right but I'm not sure drilling deeper is of any benefit. Probably doesn't hurt anything though. When I emailed the contractor and asked him WHY he is drilling so much deeper then the casing he never replied. I made sure to ask in a very respectful way. I'm a contractor too and I hate it when a home owner second guesses me or accuses me of trying to screw them over. As respectful as I was, he never replied back.

I had another contractor tell me he could do the job for 1/3 the price and the quote he gave me was more in line with what I'm use to seeing in both depth and hearing about in price. His price being so much lower is kind of alarming though. Someone is way off here. Either the first guy is way high or the second guy is way low. So I'm trying to get a few more quotes but there just aren't that many contractors in my area that do this. I'm only trying to get 28-30 GPM out of the ground so I'm tempted to go with the cheap quote but I know from experience being on the other end of these transactions that going with the cheapest bid is almost always a mistake (without knowing anything else other then price).


----------



## Tommy plumber (Feb 19, 2010)

I have been sub-contracting a well driller for well work. Very recently I had to abandon a well; I have found out that my FL plumbing license doesn't qualify me to pull a permit for that. So I subbed that out too. 

I don't think my well man will drive to your area, but if you call them and leave your number, the ladies in the office will give him your information and he'll call you back. Then you can ask him your questions. If you're interested, send me a PM and I'll get you the information.


----------



## gear junkie (Jun 20, 2008)

Going that deep can cause serious issue with salt water intrusion. When I used to drill wells in the navy, we would drill 60' below the aquaifer with 40' of solid casing at the bottom and screens 20' above and below the aquifers.


----------



## paultheplumber1 (May 1, 2014)

28-30 gpm? Holy cow. You guys got some serious water down south. I posted pics in the photo section of my guys working/pulling a 700' that on a good day gets 1.5-2 gpm


----------



## Redwood (Sep 8, 2008)

paultheplumber1 said:


> 28-30 gpm? Holy cow. You guys got some serious water down south. I posted pics in the photo section of my guys working/pulling a 700' that on a good day gets 1.5-2 gpm


Just don't run central Florida well water through copper...

It's a case of quantity over quality....:laughing:


----------



## Protech (Sep 22, 2008)

Redwood said:


> Just don't run central Florida well water through copper...
> 
> It's a case of quantity over quality....:laughing:


Actually, the well water here get's along with copper pretty good. It's the municipal water with the 3ppm chlorine that pits up the copper. I can count on one hand how many houses on a well that i've had to repipe.


----------



## AWWGH (May 2, 2011)

Our area is different here, I actually just saw my first point driven well last month which I'm assuming you see down your way? I've got wells in this area from 50' to 1600', areas were ledge is sticking out of the ground to 400' in e ground (some areas you can't get solid bedrock). If typically wells in your area are only 60' or so I would get a second opinion then.

And 28-30 gallons per minute? You guys sure are picky! Up here we take 3-4 in some areas!


----------



## Plumberdood1 (Apr 23, 2014)

I'm lucky, my house well is producing 48 gallons a minute at 50 feet down.


----------



## ToUtahNow (Jul 19, 2008)

We have a well in Utah that has 150 gpm of excellent water but we hit a void and could only grout to 70'. Because it is for commercial, Utah require a minimum of 100' of grouting. We went ahead and dropped a pump in it but we can't use it for commercial culinary. For now we are trying to find a way to use it for non-commercial residential.

Mark


----------

