Best practices include using leakproof, portable washout containers with liners, signage, and access controls

https://iris-wiki.win/index.php/Portable_Concrete_Washout_Systems:_Benefits,_Costs,_and_ROI

Best practices include using leakproof, portable washout containers with liners, signage, and access controls, positioned away from drains and sensitive areas to contain sediment and caustic residues.