Where there are several waste streams with the same identification number, is it sufficient to know the average quantities, or the maximum observed quantity, of hazardous constituents of the waste streams in order to apply the mixture rule to all of them?

No. The mixture rule provision applies only to the particular waste stream for which the quantities of all the hazardous constituents are known. Thus, knowledge that the average quantities of hazardous constituents - or the maximum observed quantity in a waste stream with the same identification number - are below their respective hazardous constituent RQs is not a sufficient basis for applying the mixture rule to all waste streams with that identification number. In such a case, the provision could be applied only to the individual waste streams for which the quantities of hazardous constituents are known.