Any tank installation initiated within the first year of the contract start date and any tank removal at the end of the contract period must be included in the rental rate offered. Tank rentals initiated after the first year of the contract start date may be charged a prorated rental rate amount based on the number of contract months remaining. If any end using entity wishes to terminate tank rentals prior to contract end, costs associated with tank removal may be invoiced to the using entity at no more than cost plus fifteen percent (15%). Removal of Contractor installed equipment must occur within sixty (60) days of tank rental or contract termination.