In the construction industry, sometimes dealing with concrete slurry is unavoidable. Unfortunately, concrete slurry waste is prohibited from being dumped straight down the drain, due to its harmful nature. After using a slurry solidifier like Gelmaxx, is it legally safe for contractors to toss the resultant material straight in to the dumpster?
Yes, it is completely legal and compliant with Environmental Protection Agency (EPA) standards. The material must pass one of the most important tests, the EPA Method 9095B Test. Within a five minute test period, nothing can pass through a paint filter, or the material is deemed to contain free liquids. If free liquids are present, then the material is unacceptable in landfills.
The EPA states that free liquids can be placed in a landfill if all of it has been “solidified so that free-standing liquid is no longer observed or has been otherwise eliminated”. Some landfills might question the disposal of the solidified slurry because of their unfamiliarity with the material; however, EPA documentation states that is perfectly acceptable for landfills once it is completely solidified.
Furthermore, only certain slurry solidifying brands like Gelmaxx are acceptable for landfills because of the Toxicity Characteristic Leaching Procedure (TCLP). This is a sample method for chemical analysis used to simulate leaching in a landfill. In other words, the TCLP determines whether the liquid that excretes from the solids will carry any environmentally harmful substances. Make sure to get a product that encapsulates the heavy metals and keeps the slurry from emulsifying and leeching into the landfill. However, please keep in mind that if the concrete slurry has harmful toxins before solidification, it will still be considered hazardous after solidification.
Now is it legally safe for contractors to dispose solidified concrete slurry directly in the dumpster? Yes, because it abides by all the EPA standards for proper liquid waste disposal.
 Authenticated US Government Information, p. 473. http://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol25/pdf/CFR-2010-title40-vol25-sec264-314.pdf