Check out Itzick and Joe’s blog post on the ASOR blog entitled Archaeology for the Masses: Tearing Down the Barriers between Archaeology and the Public
Here is a snippet:
From Day 1, an open door policy was initiated at Tel Burna; anyone is welcome to join, for as long as they like. One of the main concerns is ensuring that the quality of archaeological work remains high. This has prevented other projects from taking on groups or individual volunteers who are not willing to commit to a specific amount of time, where they can gain training necessary to excavate without damaging them. In order to overcome this challenge, our excavation limits its work not according to the number of volunteers, but rather by making sure there are enough archaeological staff members that can provide proper training and oversee activity to make sure that excavation is done properly. At times, groups are steered towards less sensitive projects, such as cleaning agricultural installations carved into the rock, or surveying. However, on a whole we have found that the presence of “untrained” excavators has not posed a problem for the quality of work.