There is disclosed a waste treatment process for a fossil-fuel extraction site (18, 40), comprising: processing extracted waste generated by a fossil-fuel extraction process to produce primary waste having a higher calorific value than the extracted waste; mixing the primary waste with secondary waste to generate pyrolysis feedstock, the secondary waste having a lower calorific value than the primary waste; pyrolysing the pyrolysis feedstock in a pyrolysis unit (32) to form pyrolysis char; and gasifying the pyrolysis char in a gasification unit (36) to form syngas and ash.