I was asked if i could remove the center of a man hole lid (cut out) off a storm drainage and weld or fab up some type of grated "bubble" over the made opening. The problem is the small openings in the lid now 1" x 4" get covered up with weeds and dont allow for the water to enter. So we are lookng at making some type of arched grate that raises about 2' above the lid with at max. 4" x 4" openings. And NO these are not in the middle of the roadways they are through out the landscaping in a subdivision. Any ideas and can I weld to the cast iron if I preheat without any problems? Or just maybe they should take care of the weed issues! HA