Play ball — but not in that dirt. La Salle Northwest Elementary School students (from left) Leonardo Canchola, Kaylie Luaisa, Olivia Lampson and Adriel Diaz kick a soccer ball in a recess area after school Tuesday as a bulldozer levels dirt next to them. The U.S. Environmental Protection Agency started cleaning up contaminated soil at the school last week, in response to contamination from the former Matthiessen and Hegeler Zinc Co. in La Salle. The M & H site is about 1.4 miles from Northwest. Last year’s initial testing zone was north and west of the M & H site to just west of Route 351 on the west and a block north of O’Conor Avenue near Illinois Veterans Home on the north, but the school got priority testing because it’s a school. The Environmental Protection Agency said an area of about 54,500 square feet will need to be excavated at Northwest. Some of the areas only need to be excavated to a depth of 6 inches, but other areas need to be excavated to a depth of 24 inches.