Abandoning a drilled well

[RLE]

I have a drilled 6” well that I need to abandon, utilizing Maine guidelines (Bentonite mix, etc). I have received a quote of over $7K for a well driller to abandon it. That’s not an option, so I am doing it myself. The well is 365’ deep with 20’ of casing, and supplied 1 gal per min when it was usable. It has not been used for about six or seven years. The water is currently sitting at 10’ below grade in the casing. The well casing is just above grade. .

I basically need to pump out approximately 70 cu/ft of water before I can fill it in with the Bentonite mix to avoid bridging. My plan is to find ~380’ of black poly pipe, either 3/4” or 1” and a used well pump on FaceBook Marketplace - or somewhere else. My question is: 1) What size (HP) pump should I try to find; 2) Should I try to find a submersible or above ground pump; 3) And, any other suggestions you think might be helpful.
Thank You!

 

[Reach4]

The only part I can help you with is to point out that an above-ground suction pump can only be relied on to pump water down to about 25 ft or so below the pump.

 

[Sponsor]

 

[Bannerman]

I understand the usual method is to install a 1/2" diameter length of poly pipe, extending above the well casing, all the way down to the bottom of the well, then fill.the well bore with mixed concrete to about 2' below the top of the casing. The weight of the concrete will push the water up through the poly pipe under pressure so the water can be eliminated without creating voids in the concrete. The poly pipe will be cut off just above the top of the concrete pour, then plugged. Additional concrete will then be added to top off the casing to the top, thereby also sealing off the.top of the poly pipe and plug.

 

[Valveman]

The reason plugging a well is expensive is the casing needs to be pulled and the well filled with cement/bentonite slurry from the bottom up. When pumping the slurry down, the water will be displaced and come out the top. It is not hard to put a pipe down and pump in the slurry. The problem is pulling the trimmy pipe before the cement hardens. The slurry needs to be put in under pressure from bottom to top to make sure there are no voids. Pumping the water out doesn't mean the slurry won't bridge or fail to fill voids when poured in from the top.

 

[rle26]

Thank you all for your responses. All good information and I appreciate your taking the time.