Although considerable volumes of leftover concrete can be reused productively back at the plant, some amount of leftover concrete disposal is still required by most producers on a daily basis. The disposal of leftover concrete, and the water used to wash out this concrete, is one of the most serious environmental issues facing the concrete industry today, and requires proper, environmentally sound execution. The National Pollutant Discharge Elimination System regulations require the discharger of any pollutant to waters of the United States to obtain a permit for the discharge. Given these regulations, it is highly advantageous to eliminate or minimize the production or discharge of leftover concrete or slurry water, as discharges of these materials require NPDES permits.
To minimize or eliminate these permitting concerns, the ideal solution is to reduce the occurrence and need for disposal of leftover concrete and slurry produced from truck, drum, and chute washing. One answer is to make a concrete reclaimer part of daily operations. Leftover concrete, or dirty wash water from drum, chute, and truck washing is discharged directly into the reclaimer. Inside, aggregate can be removed by way of mechanical and hydraulic means to produce washed sand and gravel, usually leaving a slurry to be discharged from the unit. This slurry can then be reintroduced into new batches of concrete, or it can be discharged into a series of settling basins, and then reused for additional concrete batches, washing equipment, or as an NPDES permitted discharge.
Another substantial benefit of a reclaimer is that it produces marketable products, which can result in increased profits. Washed sand and stone can be sold as reclaimed aggregate or reintroduced into future concrete batches. Slurry or cement fines can be used for a variety of products such as flowable fill.