Well casing material question

bugstruck · Aug 5, 2006

Dave, Steel well casing should make 100 years. I'd have already cracked a PVC well case in a less than observant "Loader" moment. Steel, just scratched. Cracked (grouted) well casing can't be a fun repair, regardless the material. 100 years in the sun for PVC can't be a good thing either. I'll put my money on the steel.

EDIT. There are other arguments for steel. Sub surface stress cracking and Biofouling on the inside of the casing being two. Both are documented as worse with PVC than with steel. That stress cracking is in locations with no sunlight too.

turnkey4099 · Aug 5, 2006

I would not want any PVC sticking out of the ground. It deteriorates in the sun and is easily damaged if hit. I am surprised that any well driller would do it that way, I suspect, as someone else said, that they use PVC to near the top and then steel.

I watched both mine and my neighbors wells drilled. After drilling the _hammered- the casing in. PVC would not take that.

Harry K

bigballer · Aug 7, 2006

yup, WA state drillers use mostly steel casing, my well was just finished this weekend - 140ft of 6" dia steel. I talked to the driller about this and he said if they hit basalt and have to drill through it they would line with PVC otherwise steel was used all the way. they didn't encounter any basalt or other bedrock on mine, mostly sand and silt. Here in WA drillers have to at least use steel on the first 18 feet for the surface seal/benonite but after that it's up to the owner if they want to put in steel or PVC. I opted for the steel because if the water table ever drops and i need to have them come back to go deeper, they can basically start where they left off and go further.

cheers,
bigballer

CurlyDave · Aug 7, 2006

Let me expand a bit.

The well we just drilled in Oregon was finished with both a steel casing and a PVC liner.

After drilling, they drove 75' of 6" diameter steel casing (not galvanized), which was about all they could drive, and then inserted 720' of 4" PVC into the casing which went nearly to the bottom of the drilled hole.

All of the wells are finished like this. There is about 2' of the steel casing sticking up out of the ground, and the PVC is inside it.

bugstruck · Aug 7, 2006

Dave, I like what you describe on your well. Sounds like a smart approach, combining the two. Also, your not fracturing the PVC while driving it in that way. Around here the PVC casing is always exposed at the well head. That's my biggest objection to how we do it back east. All PVC is the cheapest method though. You guys on the west coast seem to build for more durability than we do here. Guess the shifting ground or other influences force some thought and better engineering.

dfkrug · Aug 7, 2006

Our wells around here in CA are cased with PVC as far as I know.
Mine sure was. There is also an iron bacteria problem in this
area, which can completely clog up a well with a black sludgey
material. As I recall, my well was drilled 8 3/4" and lined with
6" schedule 40 PVC, with a concrete sanitary seal in the top
50 feet.