Underlying hazardous constituent
Underlying hazardous constituent means any constituent listed in 268.48, Table UTS - Universal Treatment Standards, except fluoride, selenium, sulfides, vanadium, and zinc, which can reasonably be expected to be present at the point of generation of the hazardous waste at a concentration above the constituent-specific UTS treatment standards.
Source
40 CFR § 268.2
Scoping language
When used in this part the following terms have the meanings given below: