You would have to add a well pump, electric, solar, or wind etc. You would need to find out what the well flow rate is. If it is an Artesian well, it should be more than adequate.
If it's a true free flowing artesian well there would be no need for a pump or anything. If it truly is a free flowing artesian well it may be just capped at the present time. If that is the case it's just a matter of connected some pipe to it with a shut off if need be, and running it to the pond. Also artesian wells come in all kinds of flow rates and some are not much more than a trickle. Many are not permanent either. Sometimes as surrounding land owners use more and more water with increasing development even good flowing artesian wells dissipate due to a decrease in the amount of water in the aquifer and a subsiquent decrease in pressure in the confinement.
Keep in mind the word artesian is sometimes misunderstood and used incorrectly. Artesian usually refers to a confined layer which is putting pressure on a water aquifer. It depends on how much pressure whether you have a free flowing artesian well, if drilling pops into this confined layer. My wells are my property are considered artesian, but although there is enough pressure to bring up the static water level much higher than the aquifer, there is not enough pressure to cause them to free flow.
Back to your sand vein; If your sand vein truly is a small area under the beach, I wouldn't even consider a liner. Much more expensive and they have their downsides. A good thick layer of clay should take care of the problem.
My 3/4 acre first pond was according to my contractor and Conservation agent a big risk as I had the most beautiful sandbox sand and gravel and stone at the 15 foot level where we proposed to put in the pond. But I wanted a pond badly and the contractor said he would not dig deeper than a certain depth and make sure we had at least three feet of packed clay on the bottom. You know what? This pond is been the most leak proof pond I have with non problems whatsoever.
