Washout
Rinsing residual concrete from chutes, pumps, and tools, and the designated containment where that highly alkaline slurry is collected rather than discharged to the ground.
What does washout mean?
Washout water is strongly caustic and can kill vegetation, contaminate soil, and violate stormwater permits if it reaches a drain or waterway. Regulated sites require a lined or prefabricated containment, and the hardened residue is later broken out and disposed of or recycled. Some producers reclaim washout water as mixing water under a qualifying specification.
In practice
Letting a driver rinse the chute onto the homeowner's lawn kills the grass and, on a permitted site, is a citable violation.