fast growing privacy trees
I am hoping for suggestions from experience on what would be the best type of tree to use for a privacy barrier to run about 250 to 300 feet. I am located in zone 5/Eastern Washington State. We are looking pretty much for a total privacy barrier at a height of at least 15 feet or more. We have been told the hybrid Willow or golden willow would be good choices for this region and for what we are looking to do. The question we have is that we have read where the roots can be a bit intrusive on sprinkler and or other type of underground pipes and was wondering if anyone had any idea how much area around these type of trees would be safe. Plus from experience can someone give us an idea on how far apart these type of trees would need to be planted to obtain quick privacy. The images we have saw of the hybrid willow the tree looks huge and you would think 10 feet apart would be plenty but we have read from a little as 3 to 5 feet apart. Anyway any tips or suggestions would be appreciated a great deal. Cost of course is a factor as well. Plus any other type of tree suggestions would be appreciated as well if there are any others that would do the job.
Thank you, Frank