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Wisconsin Well & Water Systems, LLC |
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| E-mail us: bruce@affordablewells.com Call us: 800-995-5004 | |||
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Information on PVC wells. Applications, advantages, code requirements & history. |
PVC Well Information... The use of PVC well casing for private water wells has been part of Wisconsin's Private Well Code since 1975, but many people in central Wisconsin have never heard of a PVC well! The primary reason is that much of the drilling conditions in this area require the use of 6" steel casing in any (bedrock) formation where the casing cannot be advanced. In the same code revision, the reasoning that went into requiring steel casing in bedrock wells was that, if a troublesome formation were encountered in the open bedrock formation below the casing, and you could not drive the casing further to seal off the problem area, a liner could be installed allowing the well to be completed without having to start all over. Furthermore, steel was required as there was concern that the trauma of drilling through PVC casing may damage it. Because of this requirement, many of the well drillers over the past 30 years have optimized their equipment to construct 6" steel wells very efficiently. There are many areas of Wisconsin that have sand & gravel formations over the bedrock. While many people choose to have 2" wells & jet pump systems installed in these areas, we believe that there are many advantages to a PVC well. Let's cover some of those PVC advantages:
COST:
This chart compares the expected average cost of a 65' screened well in a sand & gravel formation. All wells would be completed with pump hook-up. The 2" well would have a 1/2 HP jet pump, 6 gallon captive-air pressure tank and either have a pitless adapter hook-up or the pump assembly would be located in a pump house. The other wells would have submersible systems.
Expected Life Span (SCREEN): In a sand and gravel formation well, you generally need a screen to keep the sand out. (Not all screens are stainless steel! We generally use Alloy Machine Works screens. You can find out more about them here: http://www.alloymachineworks.com/products.htm) The life span of the screen---or how long it takes to plug up---depends a great deal, among other things, on how much open area is available. Imagine a rectangle 2" x 10". That is about how much open area (in inches) you have in the screen in a 2" well. Shorter than a ruler, and not much wider. Now Imagine a rectangle 8" x 10". That is about how much open area (in inches) you have in the screen in a 4" Budget well. Just a little smaller than a sheet of paper for your water to come through. Now Imagine a rectangle 10" x 13.5". That is about how much open area (in inches) you have in the screen in a 4" Non-Budget well.
This chart compares the average open area of a well screen, in inches. It is not uncommon to have to change a 2" well screen after 10-15 years at a current cost of $500.00-$800.00. If you have four times the open surface area, it should take more than four times as long to plug up. The 5" and 6" wells use exactly the same screen. The 4" budget well has a shorter screen than the Non-Budget well, but uses the same diameter.
Expected Life Span (CASING): No chart this time! PVC is completely impervious to corrosion! PVC is not susceptible to common problems with Acidic Water, Iron bacteria, Ferrous or Ferric Iron, Soil PH, Bacterial Agents. Rust and scale that build up on steel casing will not happen with PVC. The scale that precipitates off and clogs your washing machine screened inlets and kitchen faucets simply do not happen with PVC casing. If you have any iron resident in your source water, it is not complicated by the PVC casing! In a well, you at least hope you have water, right? Any time you have water, Air and steel, you are going to have at least some rust. Replace the steel with PVC and you have eliminated a lot of problems!
The The Plastic Pipe and Fittings Association lists many benefits to PVC pipe on their web Site. 79% of the 30,000 or so wells constructed annually in Michigan are PVC.
Maintenance: Have you ever heard that it is difficult to change a submersible pump in a 4" well because the pump gets stuck? In a STEEL well, anyway! That's because the pump is typically 3 15/16" in diameter, and inside of a 4" well that only leaves a little less than 1/10 of an inch all around the pump. When the well casing begins to corrode & rust, it does not take a lot of build-up of scale to make it difficult to remove and replace the pump. PVC casing eliminates this problem! Decades from now, the inside diameter will be exactly the same as the day that your well was installed!
Furthermore, the way that a submersible pump is designed, the water must flow more closely past the motor to the intake of the pump. The closer tolerances that you have in a 4" well actually cool the pump motor more effectively by creating more water flow directly past the motor housing. This takes more heat away from the motor, rather like a car radiator cools the engine in your car! Since the greatest enemy of your pump is heat, this can lead to longer pump life! Franklin Electric, the manufacturer of submersible pump motors, actually recommends the use of an "inducer sleeve" on some pumps to allow for adequate cooling of the motor. Is a 4" well, this is not necessary! See http://www.franklin-electric.com/Manual/AIM_06.htm#water
Handling: 6" Steel Casing= 440 lbs / 21' length 5" PVC Casing (SDR 21) = 59.30 lbs / 20' length 4" PVC Casing (SDR21) = 38.44 lbs / 20' length
Wisconsin Well & Water Systems, LLC 800 995-5004 Toll Free 608-584-5002 Fax 608-584-5000 Local
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© 2005 Wisconsin Well & Water
Systems, LLC. All rights reserved. |
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