Mornin Tom,
A good friend of mine who lives just down the street from me is in the water pump business and a few years ago expanded his business with a rotary well digging truck. An exoensive piece of appartus for sure. As others have said, a rotary is much faster, and usually on site no more than a few hours or no longer than a day. Depending upon soil conditions, and amount of rock that you are drilling through can determine how water flows into the well. In our area in the northeast, quite often to get sufficient gpm for a useable well a fracing sp? rig is brought in to systematically flush the walls of the well and allow better water flow to occur. Years ago when pounding a well with the conventional rigs of that time, that procedure was not used. There are very few pounders left in this area now, simply because it takes much longer, not cost effective, and everyone these days has some kind of a schedule to meet! There are a few old timers that still provide this service, but not many.
When I drilled my well at my Ct in 82, I had a pounder do it. They dug 165 ft and I had about 5 gpm at the time. As more and more homes were built in the area, and the aquafer was effectively lowered, we began to run out of water! Then in 2000 I had a rotary rig come in and deepen the existing well to 450. After they completed there work I still wasnt getting much water, so I had to pay to have the well fracked, which is a way to cleanse the veins in the rock in 20 ft intervals I believe. After that I had plenty of water, my static water level is abou 40 ft below grade at present, giving me a pretty huge reserve. This method was expensive, but it worked. For the redrilling and fracking I paid about $6000. When the well was originally drilled with the pounder in 82 it was $7 per ft so the total was about $1200 plus the price of a pump and hookup.
Hope this helps.
scotty
ps If you have the time to get the well pounded and the cost savings are there it could work for you.