400 ' Deep well 3

[machmech]

Hello Folks

I am looking at building a house in an area of Minnesota and the builder knows homes in this area require a well 400 feet deep. The average for this County is 200 Feet.

Other then higher HP motor, more pipe and wire. Are there other significant expenses I may face if so what are they?
What about maintenance? How often? What procedures?
If there is a good link on this subject please direct me to it.

Thanks, Chuck

Getting older is inevitable
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[BigInch]

Longer and ... thicker wire and heavier wall pipe.

There's really not much difference between a 200 or 400 ft well, other than the ones you mentioned already, except when it comes to doing maintenance in the hole. Pulling the pump takes a lot longer and fishing for lost or damaged items that have fallen in is a bit more difficult. Expect 2 to 3 times the maintenance costs of a 200 ft well. If your well is good quality, I'd estimate that service will be needed every 5 years. With poor quality corrosive water, it could be every 2 to 3 years.

Most of the states have an agricultural extension service with an office in each county and are happy to give you tons of free information and advice. They also usually have access to a local database of many wells in the area.

Good Internet sites,

http://watercenter.montana.edu/training/obpdf/default.htm

General Info related to residential water and sanitary systems by pump and accessory products mfgr,

http://www.goulds.com/

http://www.goulds.com/master.asp?ID=3#7

http://www.goulds.com/product.asp?ID=290&MASTERID=3

State Water Resources, Search for (your state) + "Water Resources"
California,

http://watersupplyconditions.water.ca.gov/wells.cfm

Texas,

http://texaswater.tamu.edu/groundwater.drinkingwater.html

Where to drill,

http://www.lifewater.ca/Section_2.htm

EPA Safewater Site,

http://www.epa.gov/safewater/dwa/electronic/tncws.html

Regulations,

http://www.epa.gov/safewater/dwa/electronic/ematerials.html#npdwr

Going the Big Inch!

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[machmech]

Thank you, There is a lot of good information here, I will read through it later after work. I have always been on city water supply and lack any experience of private well supply. Since there is a possibility of water treatment I must consider all the expenses.

Chuck

Getting older is inevitable
Acting your age is optional

 

[BigInch]

Just noticed you did say Minnesota.

Well locations,

http://www.dnr.state.mn.us/waters/groundwater_section/obwell/locations.html

Groundwater level,

http://www.dnr.state.mn.us/waters/groundwater_section/obwell/waterleveldata.html

Minnesota Health Dept Wells, borings Laws,

http://www.revisor.leg.state.mn.us/stats/103I/

The other sites seem to have more specific information, but
here's the University of Minnesota's Extension Service,

http://wrc.umn.edu/

http://wrc.umn.edu/outreach/index.html

http://septic.umn.edu/homeowner/index.html

If you read all of that, you'll probably know more than your contractor.

Going the Big Inch!

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[bimr]

You should also be aware that you may require water treatment equipment to improve the water quality. That might add $1,000 to your project.

 

[semo]

Having a deeper well doesn't necessarily mean more HP, longer/thicker wire, more pipe, etc.

The drawdown level of the water in the well will determine how deep the pump setting is. It is possible that a 400 feet deep well will have a similar water level as a 200 feet deep well.

As mentioned above, one of the state/county agencies will have some info to help show what neighboring wells are like.

The deeper well will cost more to install. Depending on the type of well (consolidated/rock or unconsolidated/sand&gravel) the construction materials could be heavier/thicker. The type of well and water quality will also affect future maintenance.

 

[BigInch]

Hah? Yes possible, but tell me why this guy would you want to drill a 400 ft well, if he could get to water at 200 ft?

Assuming you have a deeper well, because the water is farther down, when doesn't a deeper well mean more HP, longer or thicker wire and more pipe? The only "when" I can think of is if you are comparing an overly designed well to a well that has used its materials efficiently.

You've got twice the piping, therefore more pipe weight, more water weight in the pipe, therefore more stress and much more possible stretching of the pipe. To have the same stress level at the top pipe and all the way down the string as pipe in a shallower well, the wall thickness of each of the pipes must be correspondingly greater. Angular displacement at the bottom of the string from starting and stopping torque can also be much greater.

Could you give an example of a well 400 foot deep well with water at 400 ft +/- vs a 200 foot well with water at 200 ft +/- where what you say might be reasonable?

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[thewellguy]

As a well driller, would also question why you are getting a quote for a 400' weel. There are usually several different auqifers in the ground (I am not familiar with the local geology) and each usually has a different water quality. This may be the reason for the difference in the depth. I would strongly recommend that you get a quote from another driller and when you pick a driller get a signed contract that spells out exactly what you are getting. Choose a driller that is licensed,bonded, and insured.

The moderen well system is for the most part maintance free. If you require water treatment then you may be required to do a small amount e.g. add salt to the softner.

The ngwa.org has alot of good info on well.

In regards to biginch's comments, while he is correct, he is making the system more complicated than it is in practical application. different water aquifiers have different static heads based on the conductiveity and pressure on the formation. In northern Il there is an auqifer at around 2000' that has a hight static level that the one above it at 1500'. So it is dependent on the formation. In general a normal residential well that is 200' or 400' deep with have the pump set in the well on 1" PVC pipe. The issues of pipe strech, pressure and other are not normally of concern.

 

[BigInch]

Thewellguy,

Thank you for making it clear why I would consider drilling a 400 ft well and setting the pump at 200 ft. I did not consider "getting lucky". Striking high aquifer pressure would indeed allow you to do that.... well, at least until all the neighboors did it too. Then maybe you'd have to lower the pump.

I agree that the other concerns may not be relavent for a 1.5 HP light weight pump in a typical residential application, but I think they should be kept in mind for any well designed installation, regardless of horsepower.



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[thewellguy]

Big Inch is right, that the issues of proper design are alway important.

 

[semo]

I know the wellguy said a lot to answer things.

I don't know what the ground conditions and aquifers are in Minnesota; but, I do here in southeast Missouri.

Looking at what the County averages are won't tell me anything about what the depth needs to be in one particular location. Wells in that immediate area will give me a better idea; but, isn't guaranteed. From an existing 400 gpm well of good quality, I've seen a well drilled approximately 800 feet away where nothing but mud was found and then another well drilled 900 feet away get 100 gpm of salty water.

As mentioned above, aquifers can and will be at various depths. The water quality and quantity from these aquifers can also vary. At times it might take multiple aquifers to provide enough volume for the needs. It isn't as big a deal with residential wells; but, it can be for municipal wells.

I will basically say ditto on the wellguys statements regarding the static water level and formation pressure. The transmissibility of the aquifer and diameter of the well also has an impact on the drawdown level which has an impact on the pump setting.

Part of proper design is not oversizing the pump and motor until you actually know what the static and drawdown levels are. Can you take an educated guess if you know what surrounding wells are? Yes, but, you don't actually know until the hole is drilled and the levels are measured.

And I also agree that for residential design the smaller piping sizes provide overkill for the pump design and are typically of little concern.

 

[machmech]

Hello and Thanks for all your replies, Utilizing one of the many good links from BigInch this is some data I came up with, which is considerably accurate to what the builder told us. I got as close to the location as possible, I am understanding some variation from what you folks posted. Of coarse I don't comprehend this data compared to your experience but as I read some of these interesting facts I am gaining a better understanding of what to expect.

http://www.dnr.state.mn.us/waters/groundwater_section/obwell/waterleveldata.html

Well Details:

DNR Obwell Number: 43000
MN Unique Well Number: 243980
Nearby Town: GLENCOE
Location (Txxx Rxx Sxx): 115, 28, 11
Well Completion Date: 9/16/1971
Construction Details:
Well Depth (ft): 500
Well Diameter (in): 5
Casing Depth (ft): 446
Screen Length (ft):
Casing Material: S
Measuring Point Height (ft):
Ground Elevation (ft): 1020
Elevation Determination Method: TOPO
Aquifer Type: Bedrock
Aquifer Code: CMTSCMTS
Measurement Status Code: NO
Measured By:
Water Level Data:

Depth to
Date Water
(feet bgl)
11/17/1972, 142.89
04/20/1973, 142.52
06/27/1973, 143.72
07/20/1973, 143.93
08/24/1973, 143.46
09/25/1973, 143.41
11/01/1973, 143.44
01/08/1974, 142.98
02/07/1974, 143.45
05/21/1974, 142.2
This went on but averaged about the same down the list.

Thanks again, Chuck

Getting older is inevitable
Acting your age is optional

 

[BigInch]

Land of 10,000 lakes, a few of which are underground.

Exactly as the wellguy says; 500 ft well, but a relatively shallow pump depth. Nice. You're off to a good start.



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[thewellguy]

I thought of one other thing while reading the posts. I would strongly reccomend a 6" well. The reason being the well pumps are 4.75" in diameter. Inside a 5" well that only leaves 1/8" on any "side" (the pump is round) of the pump. If there is any mineral or scale build up the pump can easliy get stuck in the well. This can get expensive when it comes time to service the well in the future.

 

[machmech]

Thank you wellguy that sounds like good advice and I will question this, we have hard water and a lot of what I always referred to as lime scale, it is a very hard white cement like build up. I would rather pay a little extra now to save big a few years from now.

Chuck

Getting older is inevitable
Acting your age is optional

 

[kenvlach]

My 2 cents:
Aquifer levels are falling in many areas due to irrigation, population growth & demand, mine dewatering projects, and even possibly climate change. Also, deeper GW is less likely to be contaminated (nitrites, bacteria, pesticides).
Viruses have been found in 800 ft wells, maybe from improperly cased or abandoned wells.
"Groundwater is perceived as being pure, but between 1991 and 2000, more than two-thirds of the 163 waterborne infectious disease outbreaks in the U.S. were attributed to groundwater contaminated by viral, bacterial and disease-producing agents..."

http://www.jsonline.com/story/index.aspx?id=437452

Maybe good insurance to initially put in a deeper well.

 

[psmart]

When drilling our well in New Hampshire, the yield was only 1 GPM at 300 feet. After drilling to 400 feet we got 60 GPM, with a static level that was overflowing! So we only needed a 1/2 HP pump set 50 feet below ground. You never know until you drill.

 

[thewellguy]

In response to kenvlach, I beleive that you are incorrect. The termamology is the issue. Yes you are correct that there have been many disease outbreaks caused by water. the important difference is well or ground water ans surface water. The water in well ha not been the problem it is the water that comes from lakes, rivers, streams, ect.

 

[kchayfie]

The article cited by kenvlach is clearly referring to groundwater. I wouldn't like to comment on the validity of the argument posed by the article but it is not a terminology problem.

 

[GarySCWSVI]

In response to thewellguy. Groound water can be and is in many cases the problem. One who thinks because they are supplied ground water so their water is safe has another think coming. Surface water are more susceptible to contamination, however, ground water is very susceptible to contamination.

Gary Schreiber, CWS VI
The Purolite Co.