Below are comments from the client building Scuppers on Chincoteague Island in Virginia.

“I’ve attached the very first pictures where the first piling was being driven.  The aqua color machine is like a jack hammer that vibrates/hammers pilings a majority of the way down.  The yellow machine is the pile driver itself.  Orange marks are painted in one foot increments on the pilings.  The building inspector then stands by and counts/watches to make sure there are 24 to 25 hits/pounds (with the pile driver) per foot.  In the event the piling takes fewer than 24 to 25 hits per foot, and the piling reaches its maximum usable depth, a longer piling is required.  My lot took 35 foot pilings.  24 to 25 hits per foot is referenced as “driven to refusal” and is considered the necessary load carrying pressure for each piling.  We used 40 pilings in total including all deck supports.  
…you will notice a man toward the front of the lot directing another man next to the piling using hand signals.  The first man referenced is using a yellow ladder with an attached four foot level to eye the piling so it is driven as straight as possible with the hammer driver.  The second man is signaling to the machine operator as to what adjustments are required while being driven.  So, most of my pilings were driven at least 22 to 25 feet deep and were cut 9 1/2 foot above ground.  
Once the whalers are notched for the 2X12’s, the height under the house is at 8 1/2 feet, less 4 inches of finished concrete to be poured at the end of construction….They did hit a few hard spots on the lot so not all poles were driven as deep Thanks again Dan and I/we look forward to making your vision/my mom’s dream come to life!”
-Client in Virginia