AMEREN ILLINOIS COMPANY

Incident Narrative

ON SATURDAY, OCTOBER 2ND, 2010, AMEREN ILLINOIS RECEIVED A CALL AT 14:59 FROM AN EMERGENCY RESPONDER SAYING THERE WAS A TRANSMISSION LINE HIT NEAR MILTON, ILLINOIS. AT 15:02 DISPATCH CONTACTED A QUALIFIED EMPLOYEE WHO ARRIVED ON THE SCENE AT 15:38. GAS SUPERVISION ARRIVED ON THE SCENE AT 16:15 TO ASSESS THE DAMAGE AND IDENTIFY APPROPRIATE METHODS TO CONTROL THE RELEASE OF GAS. THE METHOD SELECTED TO CONTROL THE RELEASE OF GAS WAS TO UTILIZE A DOWNSTREAM VALVE AND A STOPPER FITTING TO MINIMIZE CUSTOMER IMPACT. ADDITIONAL EQUIPMENT AND QUALIFIED EMPLOYEES WERE DISPATCHED TO THE SCENE TO INSTALL THE EIGHT INCH FITTING AND STOPPER. AT APPROXIMATELY 6:00 A.M. ON SUNDAY, OCTOBER 3, 2010, THE STOPPER WAS INSTALLED AND THE DOWNSTREAM VALVE CLOSED AT THE MILTON STATION TO ISOLATE A 3,000' SECTION OF MAIN. REPAIRS WERE STARTED SHORTLY AFTER 6:00 ONCE THE TRANSMISSION PIPELINE WAS BLOWN DOWN AND IT WAS SAFE TO APPROACH THE HIT LOCATION. REPAIRS TO THE TRANSMISSION PIPELINE WERE COMPLETED AT 10:30 AND THE STOPPER REMOVED AT APPROXIMATELY 11:00. THE APPARENT CAUSE OF THE INCIDENT WAS FAILURE OF THE EXCAVATOR TO CONTACT THE ONE-CALL-SYSTEM FOR A LOCATE REQUEST. THE EXCAVATOR WAS AWARE OF THE ILLINOIS DAMAGE PREVENTION LAWS AND THE REQUIREMENT TO CALL IN A LOCATE REQUEST PRIOR TO EXCAVATING. PIPELINE MARKERS WERE VISIBLE AT BOTH ENDS OF THE FIELD AND A CALL TO 811 WOULD HAVE REDUCED THE RISK OF THIS TRANSMISSION PIPELINE DAMAGE. ESTIMATE VOLUME AND COST OF GAS RELEASED UNINTENTIONALLY UPDATED IN SUPPLEMENTAL REPORT.