All of that, mines are so numerous in Yugoit's likely they'll never be cleared. If you read the story about this place, part states... "The airbase was used intensively in 1991, during the Yugoslav Wars. During its withdrawal, the Yugoslav People's Army destroyed the runway by filling pre-built spaces (explicitly designed for the purpose) with explosives and detonating them. To prevent any possible further use of the complex by Croatian and Bosnia-Herzegovinan forces, the Military of Serbian Krajina completed the destruction in 1992 by setting off an additional 56 tons of explosives there. The ensuing explosion was so powerful that it shook the nearby city of Bihać. Residents of nearby villages claimed that smoke continued to rise from the tunnels for six months after the explosion."
Our guys were stationed right there, Bihac and Krajina...winter of '92. The war was still on. It did have uses after too. Željava Air Base - Wikipedia