Batch mixers with rated capacity of 27 cubic feet or less for mixing cement, sand, aggregate, lime, gypsum, additives, and/or water to produce concrete, grout, stucco, mortar, or other similar products; and that comply with the following conditions; are permitted by rule.(1) An internal combustion engine rated at 25 horsepower or less may be used to power the mixer.(2) The owner or operator shall use best management practices for dust control by:(A) cleaning up spilled raw materials, waste products, or finished products on a daily basis; and(B) controlling dust in transfer systems, stockpiles, work areas, storage, and truck unloading areas.