MIDAMERICAN ENERGY COMPANY

Incident Narrative

SINCE THE INITIAL ELECTRONIC REPORT WAS SUBMITTED TO THE NATIONAL RESPONSE CENTER, THE OFFICIAL ADDRESS WAS CORRECTED FROM 25554 216TH AVENUE, ZWINGLE, IA, 52079 TO 25544. 216TH AVENUE, ZWINGLE, IA, 52054. AT APPROXIMATELY 1630 HOURS ON APRIL 27, 2012, A FIELD TILE INSTALLATION CREW WORKING FOR KUNDE DOZING AND TILING STRUCK AND PUNCTURED A 16-INCH, 960 PSIG MAOP NATURAL GAS TRANSMISSION PIPELINE, OWNED AND OPERATED BY MIDAMERICAN ENERGY COMPANY, IN JACKSON COUNTY, IOWA. THE DAMAGE TO THE PIPELINE RESULTED IN A RUPTURE THAT SUBSEQUENTLY IGNITED. THE PIPELINE WAS OPERATING AT APPROXIMATELY 640 PSIG AT THE TIME OF THE INCIDENT. MIDAMERICAN'S GAS SYSTEM CONTROL CENTER RECEIVED A LOW PRESSURE ALARM AT 1635 HOURS FROM THE SCADA EQUIPMENT LOCATED AT THE PIPELINE TAP LOCATION NEAR DUBUQUE, IOWA. THE MAQUOKETA LAW CENTER RECEIVED A 911 CALL AT 1631 HOURS FROM A RESIDENT REPORTING AN APPARENT PIPELINE BREAK AND FIRE. THE MAQUOKETA LAW CENTER REPORTED THE INCIDENT TO MIDAMERICAN AT 1649 HOURS. MIDAMERICAN WAS ABLE TO ISOLATE THE DAMAGED SEGMENT OF THE PIPELINE BY 1730 HOURS. THE PIPELINE WAS FURTHER ISOLATED BY 1855 HOURS AND THE FIRE EXTINGUISHED AT 1915 HOURS. MIDAMERICAN COMPLETED EMERGENCY WORK TO ISOLATE THE DAMAGED SECTION AND RE-PRESSURIZE THE PIPELINE BY 0600 HOURS ON APRIL 28, 2012. SERVICE WAS RESTORED TO ALL 11 RESIDENTIAL CUSTOMERS AFFECTED BY THE OUTAGE BY 1417 HOURS ON APRIL 28, 2012. PERMANENT REPAIRS WERE COMPLETED AND THE PIPELINE WAS RESTORED TO NORMAL OPERATION AT 1930 HOURS ON MAY 3, 2012. MIDAMERICAN'S INVESTIGATION OF THE INCIDENT DETERMINED THAT THE CONTRACTOR INSTALLING THE DRAIN TILE WAS PERFORMING EXCAVATION ACTIVITIES ON AGRICULTURAL LAND WITHOUT A LOCATE REQUEST. THE TILING CREW HAD CROSSED THE PIPELINE FOUR SEPARATE TIMES DURING THE DAY AND HIT THE LINE DURING THE FIFTH CROSSING. THE OWNER OF THE TILING COMPANY AND IOWA ONE CALL BOTH CONFIRMED THAT NO LOCATE REQUESTS WERE MADE FOR THE INCIDENT LOCATION.