The Heating Oil shall be free from acid, grit, and fibrosis or other foreign matter which may clog or injure the oil burner or its valves. No mixed fuel shall be permitted... Deliveries shall be made from approved tank wagons with an approved metering device for supplying printed evidence of deliveries made. Slips for each delivery must be supplied to Monroe MUA, and payment will only be made upon production of such delivery slips. If delivery is made during working hours-signature is required. Also, all delivery slips to bear "TIME OF DELIVERY." IT WILL BE THE REPONSIBILITY OF THE CONTRACTOR TO KEEP THE TANKS FILLED AT ALL TIMES. In the event that any tank at any location is permitted to run out of oil, the contractor will be responsible for filling the tank as rapidly as possible, but not more than two (2) hours after notifications. In the event that such a service is not provided, and another company is called to deliver the oil, the contractor will be responsible for any increased costs. Also, the contractor will pay the cost to repair to bring the system back online because of the lack of fuel.