Thanks for the ideas....the weed problem is not just an acre or so, it is about 40 acres just on the outskirts of the subdivision that the debris comes from. I am going to use #6 rebar and build some arches and rings that i will weld onto the manhole grate (storm drain) after I cut out the center. The Opening runs down into a series of box culverts (5' x 8') that kids love to hang out in, so i will need to be able to add a padlock onto as well.