Do you (a) tell her "that's not a project!"; or, (b) ask her "why are you wasting your student's time?"; or (c) tell her that she has great ideas and you'd like to help her plan for a more meaningful PBL unit. Hopefully, through discussion, all three of those answers come up.
This evening I saw a link to a "pbl" where the students were to calculate the volume of a soda can and then redesign a new can that would hold the same volume of soda. This is a standard activity and certainly is better than having students work 20 problems on volumes of a cylinder. I even used that same thing as a 6th grade math teacher back in 1995. I could easily have said (to this teacher), "Honey, that is NOT PBL! (while wagging my index finger)
So how should we, as fellow educators, handle this when we see it? Where do we take the conversation to make it truly meaningful for our co-teacher? We start by asking her to think about who might want to redesign a soda can. Why would they want to redesign it? How would they redesign it? Now we tell her to imagine the students being the designers. How would these designers be asked to make a change to the standard soda can? Then we tell her that she's thinking like a PBL teacher, now.
I worry, as more and more teachers become "experts" in PBL, that they will start squashing ideas and activities that other teachers want to do in their classroom. Some of these activities can make great idea starters for a pbl unit. Instead of squashing the ideas we need to be encouraging these teachers to use their ideas as jumping off points to greater things. Some of these activities are great as scaffolding pieces for the middle of the project, for example.
Take the time to help your fellow teachers learn how to build inquiry into their lessons. Help them teach their students to become better questioners. Be gentle with their (the teachers) egos. You want to help them not shut them down. It is your (our) duty to help fellow teachers be the best that they can be so that our students can be the best that they can be.