Sounds reasonable. Seems like it will be an improvement to the property. I wouldn't lock in a date yet as to when the work will be done. Let them know that you will give them at least two weeks notice before the work is to begin and that anything of theirs needs to be moved out of the yard or out of the way. I would even go so far as to say that there will be a charge of x amount to move any items out of the yard if they do not do it. Odds are if they know this work will be occuring in the spring they probably won't have anything out in the yard. Also, if a renter is home during the daytime don't have them start before 9. Try as much as possible to be courteous to your tenants. Hopefully they will be at work and it won't even interfere with there everyday life.