Pitless Adapter Installation on Seam of Well Casing

[JA]

Hello,

I am analyzing a situation where a pitless adapter was installed directly on a threaded seam of a PVC well casing. Silt and other small debris was noticed fairly recently after the installation. Two years following the installation, the area around the well caved in at which point the well was dug to the pitless adapter. It was discovered at this time that the threaded joint that the pitless adapter was installed on had separated by approximately 2 inches. This allowed for soil to enter into the well.

Our initial impression is that the pitless adapter should not have been installed on the seam; however this does not seem to be a recommendation in the installation manual. Does anyone have any experience in this?

Further, by cutting the pitless adapter into the casing, they removed a portion of the threads holding the two sections of casing together. To be exact, 17% of the threads were removed around the circumference. I would understand that by doing this, the threads were not engaged how they were designed to and therefore allowed for the sections of casing to separate. Keep in mind we are in a cold climate with a frost line of about 6 to 8 feet. The pitless adapter was installed at 8' below surface.

I look forward to hearing your opinions. Thanks in advance.

 

[EdStainless]

If the adapter was installed through the threaded section how did the joint separate?
Did the lower section of casing drop, or did the upper section get lifted?

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P.E. Metallurgy, Plymouth Tube

 

[JA]

Information from the homeowner would suggest that the upper section was lifted. The thought is that forces from frost "jacking" caused the upper section to lift.

The pitless adapter was a clamp on style that utilized two clamps to hold it to the well casing. The upper clamp was located right over the threads of the casing seam.

I should also mention that the cave in around the well happened in a short period of time in the spring, right around when the frost was leaving the ground.