*Volume Discounts Available* US Patent Number: 8,113,220 B2: The Original Concrete Washout Bag. Our EnviroSac Waterproof Chute Ready Mix Bags are designed to make cleanout more efficient and environmentally safe. Each bag is tested for strength to ensure that they minimize spills during washout while effectively handling excess concrete and has a waterproof liner. If you need to dump leftover concrete from the drum, EnviroSac Chute Ready Mix bags are for you. The bags each hold at least 1/10 yard size and fold up for easy storage in any work truck.