Some integrated waste management contracts have defined categories of waste which require a specific form of treatment which may give rise to a different marginal cost for the Contractor (relative to the majority of the Contract Waste). If the tonnage of such categories of waste is likely to be material in a RWTP and the tonnage is likely to vary significantly over time then the Authority may wish to agree to exclude the tonnage of this ad hoc waste from the Diversion Performance Deduction and Base Payment calculations and agree a tailored payment regime for each such category of waste, for example a fixed sum per unit accepted.