GTA Casino Heist Maintenance Gear

[the real american patriot eagle]

Says I must scope a waste disposal to unlock that prep mission, don't know where it and would be appreciated if someone tells me how

[PleB Hitzgi]

As far as i know it is possible to redo the "scope out the casino" missions again. You unlock locations by taking a picture with snapmatic on your phone and, if you took one from somethings interesting, you can press spacebar to send it to lester. Afaik the waste disposal is a door at the back of the casino. There are also other entrances/exits you can take pictures of. From the top of my head i know some kind of cage in the sewers (entrance is south of the casino just across the street) or the gate in the tunnel west of it in the sprinting track.