Downhole Shear Wave Velocity Testing/Wet Casing

[andylawr11]

We are looking to perform some downhole shear wave velocity measurements on an existing cased hole per ASTM D7400-08. The hole is approximately 100ft deep and cased with 2.5" PVC. ASTM (as well as other sources) recommend a "dry" hole to perform the testing. Unfortunately, our casing is filled to the top with clean water, which was used to assist with installation(groundwater at 60ft +/-). Although our geophone setup allows for wet testing, I'm trying to figure out a way that i could pump or blow the water out of the existing casing and not cost us a fortune. From what I gather, anthing over 25ft of suction is going to require a deep hole well pump or some type of jet pump. It has been awhile since I took fluids or water resources. Anyone have any experience with this? Thanks,

Andy

 

[aeoliantexan]

There are 12-volt submersible pumps that will fit inside a 2" monitoring well. You can probably rent one from an environmental equipment supplier.

An air lift will get most of it if you supply lots of air. I would try 1" PVC pipe and 3/8" air line with a short length of 1/4" ID copper tubing fitted to the bottom end. Bend a 180-degree U in the tubing, being careful not to kink it, stick the open end up into the bottom of the 1" pipe, and tape it firmly with duct tape. Run the assembly to the bottom of the hole, hold it down, turn on the compressed air.

You can blow most of the water out with some type of pipe or weighted hose and a big blast of compressed air, but be sure your casing can stand the pressure.

You can bail it with a cheap 2" plastic bailer and light rope. It will take a while and make your shoulders sore. If you can't find a bailer, you can make one with a piece of pipe, a reducer, and a marble.

To get the last little bit, mop it out with a cotton rag wrapped around a weight.

 

[andylawr11]

Thanks for the tips aeoliantexan, I had been unintentially looking at pumps intended for large volume extraction(home, business, or industrial water wells). Fortunatly, there are a few environmental services firms in the area who rent 1.88" OD submersible pumps that will acomplish the job for $65 per day. The bailer is a good tip as well, I will likely use that as my back-up plan. Thanks!

Andy