A concrete batch plant is not a cement kiln. People often confuse one for the other. A concrete batch plant adds measured amounts of sand, cement, and gravel to a large mixing drum to prepare concrete mix. This mix is much like the bagged concrete you can buy at any home improvement store. There are two types of authorizations for a concrete batch plant: Plants producing large amounts of concrete are authorized by New Source Review (NSR) permits. Plants producing smaller amounts are authorized either by a Concrete Batch Plant Standard Permit or a Concrete Batch Plant Standard Permit with Enhanced Controls. These permits limit the size and operation of the concrete batch plant. We receive the most questions about smaller plants authorized under the Concrete Batch Plant Standard Permit. For these plants, the concrete mix is usually fed with water into a concrete truck. The truck finishes mixing the wet concrete on its way to a construction site. These plants have: One or more silos to hold the cement—and sometimes a silo for cement supplement, too. A large drum raised high in the air. These drums usually look like a big square funnel on stilts, high enough for a concrete truck to park beneath it. Piles of sand and gravel. Conveyors to feed the cement, sand, and gravel to their silos or to the mixing drum. Roads on the property for the concrete trucks—and for the trucks that deliver the sand, gravel, and cement, too. The silos are the tallest part—sometimes as tall as 40 feet. With the roads, structures, and concrete batch plant of sand and gravel, the whole plant would fit on about five residential lots. But this size can vary.