Railroad Commission of Texas Pipeline Evaluation System Investigation Report Inspection Package ID = 110735 4/26/18 8:49 AM Incident ID: Page 1 of 5 1124 Contacts Company ID: 6245 Company Name: ATMOS ENERGY CORPORATION Alternate Company Name: Contact Type Pipeline Operator Name Andy Treadwell Company / Affiliation ATMOS ENERGY CORPORATION Incident Detail Investigation Status: Closed Date of Incident: 3/2/15 7:52 PM Drill? No Date Reported: 3/2/15 9:41 PM Inspector Notified Date: 3/2/15 9:52 PM Assigned Inspector: San Sein Incident Location Nearest City: Dallas Location/Street Address: 9430 Eloise Street Region: Fort Worth County: DALLAS Phone Number 601-209-0597 Railroad Commission of Texas Pipeline Evaluation System Investigation Report Inspection Package ID = 110735 4/26/18 8:49 AM Incident ID: Page 2 of 5 1124 Notes Synopsis On March 2nd, 2015 at approximately 9:52 p.m. Commission inspector San Sein received a call to investigate a house explosion located at 9430 Eloise Street, Dallas, Texas. The incident had been reported through the Commission's Emergency Line by Atmos Energy at 9:41 p.m. Earlier that evening at approximately 7:52 pm, the reported house explosion occurred at 9430 Eloise Street in Dallas, Texas. There were two injuries as a result of the incident. Both injuries were reported to be minor, requiring no hospitalization, and were experienced by the occupants of the property. Investigation (Include a probable cause statement for incident/accident investigation) Mr. Sein arrived at the location of the incident at approximately 11:30 p.m. on March 2nd, 2015 and began his investigation into the explosion. During the investigation Mr. Sein witnessed the operator, Atmos Energy, conducting a necessary leak investigation with leak detection equipment. He also witnessed an odor concentration test in order to best determine if the gas contained the proper level of odorant. Current gas pressures were witnessed, as well as cathodic protection pipe-to-soil readings. Operation and maintenance historic records were reviewed, with a concentration into leakage history and odorization, as well as excavation records and locate tickets for the surrounding area. The investigation revealed that at the time of the explosion there was a natural gas leak on the 1504 Memory Lane service line at the point where the service line connected to the main by means of a mechanical compression coupling. There were indications that the leaking natural gas had migrated into the sewer clean-out of the residence of 9430 Eloise Street. When tested, the sewer clean-out to 9430 Eloise Street produced natural gas concentrations of 5.0 percent gas. This leaking gas had apparently migrated into the residence structure at 9430 Eloise Street where it found an undetermined ignition point, causing the explosion. See also: IP 110735 attachment PHMSA Form-11. Emergency Response (Complete for incident/accident investigations) On the date of the incident, Atmos Technicians conducted bar-hole testing along the customer service line and foundation, along the main between the street and property line, at sewer traps and water meters, and a leak survey of the map sheet as noted above. The service line to 1504 Memory Ln was relocated and replaced. Additional pipeline materials from the 1504 Memory Ln and 9430 Eloise St, where applicable, were also removed by Atmos Energy's independent investigator (Baker Engineering & Risk Consultants, Inc.). Baker Engineering & Risk Consultants, Inc. is also investigating on behalf of Atmos. Atmos continued to monitor the incident scene and found residual gas readings between the retired service tap of 1504 Memory Lane and 9430 Eloise Street. Atmos is planning to replace approximately 1100 feet of 2-Inch Poly and approximately 19 services along the 1500 block of Memory Lane and the 9400 block of Eloise Street. On March 19th, Railroad Commission of Texas Pipeline Evaluation System Investigation Report Inspection Package ID = 110735 4/26/18 8:49 AM Incident ID: Page 3 of 5 1124 2015, Atmos had already replaced 328 feet of 2-inch Poly main and three services along the 1500 block of Memory Lane under Project # 080.47535. Railroad Commission of Texas Pipeline Evaluation System Investigation Report Inspection Package ID = 110735 4/26/18 8:49 AM Incident ID: Page 4 of 5 1124 Operator - 30 Day Report Part A-Key Report Information by operator Report is final? Yes OPS Operator Identification Number: 31348 NRC Number (from Incident Detail): 1109474 Volume of commodity released unintentionally: Volume of commodity released intentionally: Volume of commodity recovered: 47 0 0 Fatalities? No Operator employees: 0 Injuries requiring inpatient hospitalization? No Operator employees: 0 Contractor employees working for the Operator: 0 Non-Operator emergency responders: 0 Workers working on the right-of-way, but NOT associated with this Operator: 0 General Public: 0 Total Fatalities: 0 MCF Contractor employees working for the Operator: 0 Non-Operator emergency responders: 0 Workers working on the right-of-way, but NOT associated with this Operator: 0 General Public: 0 Total Injuries: 0 Part C-Additional Facility Information by operator Incident Occured On: Other: Mechanical Coupling Connection Failure Occured On: Material Involved: Steel Install Year: 1951 Part D-Additional Consequence Information by operator HCA or USA? No Public and non-operator costs: Cost of commodity unintentionally released: Cost of commodity intentionally released: Cost of property damage and repair: Cost of emergency response: Cost of environmental remediation: $ 100,000.00 $ 187.00 $ 1,915.00 $ 4,377.00 Other costs: Total costs: Part G-Apparent Cause from operator Incident Cause (Confirmed): Excavation Damage Sub-cause: Previous Damage Due Excavation Activity Part H-Operator Incident Summary At 7:58 pm om March 2nd, 2015, Atmos Energy dispatch was notified of an event at 1504 Memory Lane in Dallas. (Address correction during investigation to: 9430 Eloise Street.) Amos Energy's first responder arrived on-site at 9:17 pm and upon learning that homes had been evacuated by Dallas Fire Department personnel the Atmos Energy first responder began bar-hole testing and checking sewer vents in the immediate area. Soon a second Atmos Railroad Commission of Texas Pipeline Evaluation System Investigation Report Inspection Package ID = 110735 4/26/18 8:49 AM Incident ID: Page 5 of 5 1124 Energy responder and two Atmos Energy supervisors arrived to assist with the investigation. At approximately 11:25 pm Atmos Energy began a leak survey of the area with a leak, thereafter pinpointed the leak in the area of the service tap to 1504 Memory Lane, an address adjacent to 9430 Eloise Street. In the early morning hours of March 3, 2015, Atmos Energy requested emergency line locates, which were made, allowing Atmos Energy's excavation of the service tap to 1504 Memory Lane to begin at approximately 2:20 am. An active leak was discovered at the service tap connection and the service line to 1504 Memory Lane was retired at 2:43 am. Atmos Energy then began an excavation to retire the service line to 9430 Eloise street and this retirement was completed at 4:47 am. On March 10th, 2015, under the observation of Railroad Commission personnel, Atmos Energy and Baker Risk performed strategic excavation of the 1504 Memory Lane service line. Previous damage due to third party excavation was observed on the service line. Between December 13th, 2011 and March 2nd, 2015, Atmos Energy is aware of five locate requests (locate number 1475052478, 1475382044, 120450096, 120196080, and 13474488) in proximity to 1504 Memory Lane. The third party excavation damage to the service line caused the connection failure at the service tap.