According to his opinion, in Israel, the phenomenon of sinkholes is known mainly from the Dead Sea coastal area, where it is the product of a change in the level of the Dead Sea and the exposure of salt layers deep underground to contact with fresh water that dissolves it. On the other hand, in the rocks of the Adulam Formation (the natural rock at the site in the settlement of Karmei Yosef, composed of cardboard, limestone and hallway) there is no known phenomenon of sinkhole development as a result of the mass, both in Israel and around the world.
In view of the aforesaid, in accordance with the opinion, the present case is not sinkhole because the pool was built on top of a high earth fill (about 3 to 8 meters high) and not on soluble rock, and the failure stemmed from the physical erosion of loose fill particles by the pool water that leaked through a piping process, and not from the chemical dissolution of the bedrock. This is also how Dr. Yarkoni clarified, in his testimony - to the questions of Attorney Ayalon, that in the case before us we are not dealing with "natural subsidence of the soil" and in addition, the gap that was created was not created "due to" the water leakage or the dissolution of the rock, but was previously a cave filled with the wrong filler, and it is not a case of limestone or salt (which collapsed or melted).
Dr. Yarkoni clarifies that the process of piping is not a sinkhole. It is a process of underground water flow - in canals, "pipes", due to the erosion of thin components, which causes a loss of soil stability and the creation of a local collapse or even widespread collapse. Such cases are common around the world in reservoirs, dams, near streams, near leaking water infrastructures, but according to the professional geological literature, "it is not correct to define them as sinkholes".
- According to the opinion of its expert, Prof. Sam Friedman, a civil engineer, a sinkhole is a space created by the collapse of the ground surface as a result of the loss of underground support. This phenomenon usually occurs when there is an underground cavity, and can be caused by the enlargement or expansion of the space towards the surface, or by the weakening of the strength of the ground roof (for example, as a result of wetting) above the space.
Prof. Friedman bases his opinion on lawsuits, indictments, and defenses submitted to the court, and on articles that appeared in the media regarding the disaster. In addition, he bases his professional experience and expertise on findings from a visit to the site of the incident on June 12,2025.