Map crashes after 15-20 minutes into the game

[HayleyGilbert24]

Hey all I'm having another little issue. So I'm currently working on a zoo but It will crash about 15 or so minutes in and I don't know why that is happening. I'll have the file attached at the bottom here. Please let me know what is going on. Thank you :) 

Grand Junction Zoo.zoo

[Fern]

Have given it to Jay