but at the same time
I think this phrase should be replaced by "and also." There is no reason to suppose that a beneficial influence would not last a long time, so don't talk about it as though it is somehow unlikely that you could do something of lasting benefit. I think "and also" works just fine...
Oh, I like the end! alright, how about if we get rid of the sentence at the beginning that I don't like:
For my Boy Scout Eagle Project, I
wanted to do something that would positively benefit the entire community, but at the same time have a lasting impact afterwards. Working
worked with the Los Angeles Sheriff's Department at Industry Station to initiate a Community Awareness Program.
for my community.
Then, at the end of the essay you will not be repeating yourself about wanting to have a lasting benefit, etc.
I like the ending a lot...