Instead of just picking up trash, find a way to use it creatively to make something beautiful. This could be in a workshop setting on a day a month. People can work solo or make a collaborative piece. The results could be displayed in a chosen spot in Lowell. This could also involve photographers, choreographers, poets, songwriters acquiring inspiration from what they see.
It's a win-win. The streets would be cleaner, the participants would have fun with the creative process, the materials would be mostly free (neighbors could donate cardboard backings and glue) and the sense of community could be strengthened.