Our PB" subcontractors shot the gunite in about 2 weeks ago. Yesterday he had someone come out and they are literally jackhammering about 30 % of the shot gunite--mostly off bottom and sides of two opposite sections of the pool--due to the top layer not "adhering" properly. PB said he has never had happen before. It could be "because someone stepped on the gunite or the psi on the gunite shooter was not correct." Although he has never had this happen before he assures us that this is not a problem. He also had never had a subcontractor hit a gas line (last week's drama) before...I know, I know, why did they not call to have lines for gas marked>" So, right now, I am trying to educate myself on gunite. The guy that started jackhammering showed me, by hammering around the pool,and listening to the different sounds the hammer made, where the gunite had adhered properly to the bottom layer of the gunite. Can anyone give me education, advise or???