# Rupture of Hazardous Liquid Pipeline with Release and Ignition of Propane - **operation:** document - **citation:** DCA08MP001 - **title:** Rupture of Hazardous Liquid Pipeline with Release and Ignition of Propane - **source type:** incident - **agency:** National Transportation Safety Board - **status:** current - **official:** true - **published on:** 2026-01-30 - **effective on:** 2007-11-01 - **summary:** Accident. in Matherville, MS, USA. on 2007-11-01. Dixie Pipeline Company. Leak/explosion/fire - **machine formats:** - **json:** https://regulus.evalyn.ai/document/ntsb-case-dca08mp001.json - **markdown:** https://regulus.evalyn.ai/document/ntsb-case-dca08mp001.md - **app url:** https://regulus.evalyn.ai/document/ntsb-case-dca08mp001 - **source url:** https://www.ntsb.gov/investigations/Pages/DCA08MP001.aspx **body:** NTSB investigation DCA08MP001. Event Type: Accident Event Date: 2007-11-01 Event City: Matherville Event State Or Region: MS Event Country: USA Pipeline Operator: Dixie Pipeline Company Pipeline Type: Hazardous Liquid - Regulated Accident Type: Leak/explosion/fire Completion Status: Completed Report Number: PAR-09-01 Probable cause: The National Transportation Safety Board determines that the probable cause of the November 1, 2007, rupture of the liquid propane pipeline operated by Dixie Pipeline Company near Carmichael, Mississippi, was the failure of a weld that caused the pipe to fracture along the longitudinal seam weld, a portion of the upstream girth weld, and portions of the adjacent pipe joints. Tier1Name: System operating Tier2Name: Fire/explosion (post-release) Tier1Name: System operating Tier2Name: Pipe structural malfunction/failure Finding Tier1Name: Organizational Finding Tier2Name: Management Finding Tier3Name: Policy/procedure Finding Modifier Name: Pipeline operator Finding Report Text: Organizational - Management - Policy/procedure - Pipeline operator Finding Tier1Name: Organizational Finding Tier2Name: Support/oversight/monitoring Finding Tier3Name: Safety programs Finding Modifier Name: Federal agency Finding Report Text: Organizational - Support/oversight/monitoring - Safety programs - Federal agency Finding Tier1Name: Organizational Finding Tier2Name: Support/oversight/monitoring Finding Tier3Name: Oversight Finding Modifier Name: Other institution/organization Finding Report Text: Organizational - Support/oversight/monitoring - Oversight - Other institution/organization Finding Tier1Name: Personnel Finding Tier2Name: Experience/knowledge Finding Tier3Name: Training Finding Tier4Name: (general) Finding Modifier Name: State/Local government personnel Finding Report Text: Personnel - Experience/knowledge - Training - State/Local government personnel Finding Tier1Name: Pipeline Finding Tier2Name: Pipeline structure Finding Tier3Name: Joint/weld/seam Finding Modifier Name: Failure Finding Report Text: Pipeline - Pipeline structure - Joint/weld/seam - Failure Official NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations. What Happened On November 1, 2007, at 10:35:02 a.m. central daylight time, a 12-inch-diameter pipeline segment operated by Dixie Pipeline Company was transporting liquid propane at about 1,405 pounds per square inch, gauge, when it ruptured in a rural area near Carmichael, Mississippi. The resulting gas cloud expanded over nearby homes and ignited, creating a large fireball that was heard and seen from miles away. About 10,253 barrels (430,626 gallons) of propane were released. As a result of the ensuing fire, two people were killed and seven people sustained minor injuries. Four houses were destroyed, and several others were damaged. About 71.4 acres of grassland and woodland were burned. Dixie Pipeline Company reported that property damages resulting from the accident, including the loss of product, were $3,377,247. What We Found The probable cause of the November 1, 2007, rupture of the liquid propane pipeline operated by Dixie Pipeline Company near Carmichael, Mississippi, was the failure of a weld that caused the pipe to fracture along the longitudinal seam weld, a portion of the upstream girth weld, and portions of the adjacent pipe joints. What We Recommended As a result of the investigation of this accident, the National Transportation Safety Board makes recommendations to the Pipeline and Hazardous Materials Safety Administration, the Dixie Pipeline Company, the American Petroleum Institute, and the Clarke County Board of Supervisors. PAR-09-01 <<>> Rupture of Hazardous Liquid Pipeline With Release and Ignition of Propane Carmichael, Mississippi November 1, 2007 Accident Report NTSB/PAR-09/01 PB2009-916501 National Transportation Safety Board <<>> <<>> NTSB/PAR-09/01 PB2009-916501 Notation 7979A Adopted October 14, 2009 Pipeline Accident Report Rupture of Hazardous Liquid Pipeline With Release and Ignition of Propane Carmichael, Mississippi November 1, 2007 National Transportation Safety Board 490 L’Enfant Plaza, S.W. Washington, D.C. 20594 <<>> National Transportation Safety Board. 2009. Rupture of Hazardous Liquid Pipeline With Release and Ignition of Propane, Carmichael, Mississippi, November 1, 2007. Pipeline Accident Report NTSB/PAR-09/01. Washington, DC. Abstract: On November 1, 2007, at 10:35:02 a.m. central daylight time, a 12-inch-diameter pipeline segment operated by Dixie Pipeline Company was transporting liquid propane at about 1,405 pounds per square inch, gauge, when it ruptured in a rural area near Carmichael, Mississippi. The resulting gas cloud expanded over nearby homes and ignited, creating a large fireball that was heard and seen from miles away. About 10,253 barrels (430,626 gallons) of propane were released. As a result of the ensuing fire, two people were killed and seven people sustained minor injuries. Four houses were destroyed, and several others were damaged. About 71.4 acres of grassland and woodland were burned. Dixie Pipeline Company reported that property damage resulting from the accident, including the loss of product, was $3,377,247. The safety issues identified in this accident are the failure mechanisms and safety of low-frequency electric resistance welded pipe, the adequacy of Dixie Pipeline Company’s public education program, the adequacy of federal pipeline safety regulations and oversight exercised by the Pipeline and Hazardous Materials Safety Administration of pipeline operators’ public education and emergency responder outreach programs, and emergency communications in Clarke County, Mississippi. As a result of the investigation of this accident, the National Transportation Safety Board makes recommendations to the Pipeline and Hazardous Materials Safety Administration, the Dixie Pipeline Company, the American Petroleum Institute, and the Clarke County Board of Supervisors. The National Transportation Safety Board is an independent federal agency dedicated to promoting aviation, railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The NTSB makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and statistical reviews. Recent publications are available in their entirety on the Internet at . Other information about available publications also may be obtained from the website or by contacting: National Transportation Safety Board Records Management Division, CIO-40 490 L’Enfant Plaza, SW Washington, DC 20594 (800) 877-6799 or (202) 314-6551 NTSB publications may be purchased, by individual copy or by subscription, from the National Technical Information Service. To purchase this publication, order report number PB2009-916501 from: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 (800) 553-6847 or (703) 605-6000 The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence or use of NTSB reports related to an incident or accident in a civil action for damages resulting from a matter mentioned in the report. <<>> NTSB Pipeline Accident Report Contents Figures .............................................................................................................................................v Acronyms and Abbreviations ..................................................................................................... vi Executive Summary .................................................................................................................... vii Factual Information .......................................................................................................................1 Accident Synopsis ............................................................................................................................1 Accident Narrative ...........................................................................................................................1 Emergency Response .......................................................................................................................4 Accident Site ....................................................................................................................................6 On-Scene Response ..................................................................................................................7 Evacuations ...............................................................................................................................9 Conclusion of On-Scene Response ...........................................................................................9 Injuries ...........................................................................................................................................10 Damages .........................................................................................................................................10 Postaccident Inspections ................................................................................................................10 Pipeline ...................................................................................................................................10 Surrounding Area ....................................................................................................................12 Pipeline Controller .........................................................................................................................12 Pipeline Information ......................................................................................................................13 Design and Construction .........................................................................................................13 Operating History ...................................................................................................................13 Previous In-service Pipeline Failures .....................................................................................14 Preaccident Hydrostatic Pressure Tests ..................................................................................15 In-Line Inspection Information ...............................................................................................16 Tests and Research .........................................................................................................................20 Metallurgical Examination of Accident Pipe .........................................................................20 Finite Element Analysis ..........................................................................................................23 ERW Pipeline.................................................................................................................................25 Performance of Low-Frequency ERW Pipe ...........................................................................25 Federal Oversight and Studies ................................................................................................26 Postaccident Actions ......................................................................................................................28 PHMSA ...................................................................................................................................28 Dixie Pipeline .........................................................................................................................29 Postaccident Emergency Response Debriefing ......................................................................30 Pipeline Operator Public Education Programs ..............................................................................30 Regulations and Standards ......................................................................................................30 Dixie’s Public Education Program .........................................................................................31 Clarke County Emergency Management and Communications ....................................................36 Emergency Management ........................................................................................................36 Emergency Communications ..................................................................................................36 iii <<>> NTSB Pipeline Accident Report Analysis .........................................................................................................................................38 Exclusions ......................................................................................................................................38 Fracture of the Pipeline ..................................................................................................................39 Safety and Performance of ERW Pipe ...........................................................................................41 Pipeline Operator Public Education Programs ..............................................................................43 Public Awareness Program .....................................................................................................44 Outreach Program to Emergency Responders ........................................................................44 Clarke County Emergency Communications .................................................................................46 Preparedness of Clarke County 911 Dispatch Center .............................................................46 Emergency Radio Communications .......................................................................................47 Conclusions ...................................................................................................................................49 Findings..........................................................................................................................................49 Probable Cause...............................................................................................................................50 Recommendations ........................................................................................................................51 Appendix A ...................................................................................................................................53 Investigation ...................................................................................................................................53 Appendix B ...................................................................................................................................54 Accident Timeline ..........................................................................................................................54 iv <<>> NTSB Pipeline Accident Report Figures Figure 1. Map of Dixie pipeline. .................................................................................................... 2 Figure 2. Aerial view of fire from pipeline rupture showing nearby destroyed houses. ............... 3 Figure 3. Ruptured pipe at Carmichael looking southwest. (Soil has been removed from around pipe to facilitate on-site examination.) ............................................................................. 11 Figure 4. Downstream end of rupture. ......................................................................................... 20 Figure 5. Ruptured pipe. .............................................................................................................. 21 Figure 6. Schematic drawing of accident pipe identifying welds and showing fracture features of interest. ........................................................................................................................ 22 v <<>> NTSB Pipeline Accident Report Acronyms and Abbreviations API American Petroleum Institute API RP 1162 API Recommended Practice 1162 CFR Code of Federal Regulations CVFD Carmichael Volunteer Fire Department Dixie Dixie Pipeline Company DOT U.S. Department of Transportation Enterprise Enterprise Products Operating ERW Electric resistance welded GE General Electric Hunt Hunt Crude Oil Supply Company Magpie Magpie Systems Inc. NTSB National Transportation Safety Board Paradigm Paradigm Alliance, Inc. PHMSA Pipeline and Hazardous Materials Safety Administration psi pounds per square inch psig pounds per square inch, gauge SCADA Supervisory control and data acquisition Stork Stork Metallurgical Consultants vi <<>> NTSB Pipeline Accident Report Executive Summary On November 1, 2007, at 10:35:02 a.m. central daylight time, a 12-inch-diameter pipeline segment operated by Dixie Pipeline Company was transporting liquid propane at about 1,405 pounds per square inch, gauge, when it ruptured in a rural area near Carmichael, Mississippi. The resulting gas cloud expanded over nearby homes and ignited, creating a large fireball that was heard and seen from miles away. About 10,253 barrels (430,626 gallons) of propane were released. As a result of the ensuing fire, two people were killed and seven people sustained minor injuries. Four houses were destroyed, and several others were damaged. About 71.4 acres of grassland and woodland were burned. Dixie Pipeline Company reported that property damages resulting from the accident, including the loss of product, were $3,377,247. The National Transportation Safety Board determines that the probable cause of the November 1, 2007, rupture of the liquid propane pipeline operated by Dixie Pipeline Company near Carmichael, Mississippi, was the failure of a weld that caused the pipe to fracture along the longitudinal seam weld, a portion of the upstream girth weld, and portions of the adjacent pipe joints. The following safety issues were identified as a result of the investigation of this accident: • The failure mechanisms and safety of low-frequency electric resistance welded pipe, • The adequacy of Dixie Pipeline Company’s public education program, • The adequacy of federal pipeline safety regulations and oversight exercised by the Pipeline and Hazardous Materials Safety Administration of pipeline operators’ public education and emergency responder outreach programs, and • Emergency communications in Clarke County, Mississippi. Safety recommendations to the Pipeline and Hazardous Materials Safety Administration, the Dixie Pipeline Company, the American Petroleum Institute, and the Clarke County Board of Supervisors are included in the report. vii <<>> NTSB Pipeline Accident Report <<>> NTSB Pipeline Accident Report Factual Information Accident Synopsis On November 1, 2007, at 10:35:02 a.m.1 central daylight time,2 a 12-inch-diameter pipeline segment operated by Dixie Pipeline Company (Dixie) was transporting liquid propane at about 1,405 pounds per square inch, gauge (psig), when it ruptured in a rural area near Carmichael, Mississippi. The resulting gas cloud expanded over nearby homes and ignited, creating a large fireball that was heard and seen from miles away. About 10,253 barrels (430,626 gallons) of propane were released. As a result of the ensuing fire, two people were killed and seven people sustained minor injuries. Four houses were destroyed, and several others were damaged. About 71.4 acres of grassland and woodland were burned. Dixie reported that property damages resulting from the accident, including the loss of product, were $3,377,247. Accident Narrative At 10:35:02 a.m. central daylight time, Dixie’s 12-inch-diameter propane pipeline segment ruptured about 2,650 feet downstream of Carmichael Pump Station near Carmichael, Mississippi. The map in figure 1 shows the route of the entire pipeline—from Mont Belvieu, Texas, to Apex, North Carolina—which comprises various sizes of pipe from several pipe manufacturers. The 12-inch-diameter pipeline segment starts on the west side of the Mississippi River near Erwinville, Louisiana, and continues eastward about 395 miles to Opelika, Alabama. Yellow Creek Pump Station is 19.28 miles upstream of Carmichael Station. The first pump station downstream of Carmichael is Butler Station, which is 18.3 miles east of Carmichael. 1 The times associated with events indicated in hours:minutes:seconds are from either the Supervisory Control and Data Acquisition (SCADA) system or the 911 system. 2 All times in this report are central daylight time except where otherwise noted. 1 <<>> NTSB Pipeline Accident Report Figure 1. Map of Dixie pipeline. The Dixie pipeline is owned by Enterprise Products Operating (Enterprise); the controller for the accident pipeline was located at Enterprise’s liquid pipeline Supervisory Control and Data Acquisition (SCADA) Control Center in Houston, Texas. The first indication of a problem was when the SCADA control panel displayed sequential discharge pressure measurements that indicated a large change in pressure at Carmichael Pump Station. At 10:35:07 a.m., the display showed a discharge pressure of 1,079 psig; at 10:35:13 a.m., the discharge pressure was 154 psig, indicating a large, sudden drop in pipeline pressure. Additionally, the display showed that Carmichael Station’s unit 2 pump had shut down because of low suction pressure. At 10:35:46 a.m., the SCADA display indicated that the rate-of-change in pressure at Butler Station, the next station downstream from Carmichael, was starting to decrease. Also, at 10:35:50 a.m., the SCADA display indicated that the rate-of-change in pressure at Yellow Creek Station, the first station upstream of Carmichael Station, was starting to come down. When the pipeline ruptured at 10:35:02 a.m., liquid propane was released and instantaneously began to vaporize and form a low-lying propane gas cloud over the area. The propane gas did not ignite immediately; it ignited about 7 1/2 minutes later, at 10:42:30 a.m. Witnesses miles away reported seeing and hearing a large fireball and heavy black smoke over the area. The fire extended about 950 feet southwest and about 1,250 feet south of the rupture site. (See figure 2.) The fire fueled by the residual propane gas escaping from the pipeline 2 <<>> NTSB Pipeline Accident Report continued to burn at the ruptured pipe joint3 until the following day, when the fire at the pipe extinguished itself after flow control valves on both sides of the rupture were closed. Figure 2. Aerial view of fire from pipeline rupture showing nearby destroyed houses. At the time of the rupture, the flow of propane had increased from 5,952 barrels per hour to 7,354 barrels per hour. At 10:36:25 a.m., a little more than 1 minute after the SCADA display of the sudden pressure reduction, the controller decided that there was a leak in the Carmichael Station area, and he began shutting down the pipeline to reduce the amount of product released. At 10:37:12 a.m., the controller started the unit 1 pump at Butler Station (downstream of the rupture) to pull product away from the rupture area. About 10:38 a.m., the controller started calling field personnel from Hattiesburg and Demopolis Pump Stations to respond to the release. About 10:41 a.m., a person in a house in the 8500 block of County Road 630 called the toll-free emergency number for Dixie to report an explosion and smoke near her house. Dixie’s SCADA controller on duty recognized this report as indicating a product release from a pipeline in the Carmichael area. At 10:46 a.m., the Dixie pipeline controller in Houston received a telephone call in which the caller described four explosions, fire 200 feet in the air, and two columns of white and black smoke. The caller said these were in “the area where a crude oil pipeline owned by Hunt [Crude] 3 A joint is a single length of pipe; the accident joint was about 52 feet long. 3 <<>> NTSB Pipeline Accident Report Oil [Supply Company] (Hunt) crosses the Dixie pipeline.” The controller then directed a contractor in the Carmichael area to go to the site. At 10:48 a.m., a Hunt employee told the controller that the Hunt pipeline had been shut down and blocked off in the area of the release. At 10:49:51 a.m., the Dixie pipeline controller telephoned Clarke County Central Dispatch to provide notification of a pipeline leak in the Carmichael Station area. The controller was told that Clarke County officials were already aware of an event near that location and had dispatched trucks to the scene from several fire departments. The controller continued to isolate the rupture site by issuing commands through SCADA to close the remotely controlled block valves at the Butler and Carmichael Stations starting at 10:52:37 a.m. By 12:36 p.m., field technicians had closed the nearest manually controlled block valves, thereby completing the shutdown and isolation of the leaking section of the pipeline. Weather conditions at the National Weather Service station in Meridian, Mississippi, around the time of the accident were reported as a clear sky (that is, no precipitation), a surface visibility of 10 miles, wind from the north-northeast about 7 mph with no significant wind gusts, and a ground level atmospheric temperature of 69° F. Sunrise was at 6:37 a.m. and sunset at 4:49 p.m. Emergency Response The first call received at Clarke County Central Dispatch, which operates the county’s 911 emergency call center, came in at 10:39:56 a.m. Two operators were on duty at the time. The call was from a person calling from a house at 4195 County Road 621. The caller reported that a gas explosion had occurred somewhere around the area and that smoke and gas surrounded the house. When asked if there was fire, the caller said that she did not see any fire but she saw white gas and smelled gas. The 911 operator told the caller that an emergency responder would be sent. The operator did not tell the caller to get out of the house and run away from the smoke. The call lasted 1 minute 20 seconds. The house at this address was subsequently identified as the house in which one of the two fatalities was discovered. At 10:40:13 a.m., during the first 911 call, the second 911 operator received a telephone call from a caller in a house in the 4300 block of County Road 621, about 600 feet south of the house where the first 911 call had originated. The caller reported that an explosion had occurred and he could see smoke when he walked out to the road. The call lasted 1 minute 33 seconds and concluded at 10:41:46 a.m. Clarke County Central Dispatch subsequently received numerous additional calls reporting the incident. 4 <<>> NTSB Pipeline Accident Report About 10:42 a.m., after receiving the first two 911 calls, Clarke County Central Dispatch placed a radio dispatch page to the Carmichael Volunteer Fire Department (CVFD) to respond to the house at 4195 County Road 621. The Clarke County Central Dispatch operating personnel did not know at that time that their fire department radio signal repeater4 did not transmit the page to the CVFD. Later, it was determined that the repeater system did not send a signal because it had been disabled during routine cleaning in the Clarke County Central Dispatch facility when a floor mop had accidentally dislodged the connector fittings of several communication cables about 90 minutes before the accident. The assistant chief of the CVFD was at work about 1/4 mile from the CVFD fire station when, about 10:43 a.m., he heard the sound of a distant explosion. According to the assistant chief, the sound was followed shortly thereafter by the sound of a second explosion and perhaps the sound of a third explosion. About 10 to 15 seconds later, he saw a large plume and a cloud of heavy black smoke rising above the trees. The assistant chief immediately began mobilizing CVFD fire apparatus and personnel to the scene. At 10:42:50 a.m., a caller at a construction site on a road north of Waynesboro, used a cellular telephone to call Wayne County, Mississippi, 911. The caller reported that an explosion had occurred northeast of his location. In a postaccident interview, this caller indicated that he had placed the 911 call about 20 seconds after he heard the sound of what appeared to be an explosion that occurred in the distance and after he saw a large plume and a cloud of heavy black smoke rising above the trees and moving northeast from his location. Following another 911 call that was received about 17 seconds after the 10:42:50 phone call, Wayne County 911 sent a Wayne County deputy sheriff to verify the incident location, and then, under a mutual aid agreement with Clarke County, dispatched Wayne County fire and rescue units to the scene. About 10:44 a.m., because Clarke County Central Dispatch had not received a response from the CVFD acknowledging the page that had been placed about 2 minutes earlier, Clarke County Central Dispatch sent a second page, this time to the Theadville Volunteer Fire Department to respond to 4195 County Road 621.5 Clarke County Central Dispatch was still unaware at that time that the radio signal repeater was not functioning and the page to the Theadville fire department also had not been transmitted. The Clarke County sheriff was at his residence about 20 miles from the accident site when about 10:44 a.m. he received a telephone call from Clarke County Central Dispatch asking whether there were any pipelines near County Roads 630 and 621, because a 911 call had just reported an explosion in that area. The sheriff responded that there was a pipeline in the Carmichael area. During postaccident interviews, the sheriff stated that he had been casually listening to his service radio just before this phone call, and there had not been any radio traffic 4 A radio signal repeater is a combination of a radio receiver and a radio transmitter that receives a radio signal and retransmits it at a higher level or higher power to relay radio signals across a wider area. 5 In accordance with Clarke County Central Dispatch operations protocol, a page is to be acknowledged by the department receiving the page. If no acknowledgement is received within about 2 minutes, the next closest fire department is paged and directed to respond. Clarke County Central Dispatch is to continue to page and dispatch a sequence of fire departments until an acknowledgement is received. 5 <<>> NTSB Pipeline Accident Report about an incident occurring in the Carmichael area. Clarke County Central Dispatch told the sheriff that two units (deputies) had been dispatched to that location and the CVFD had been paged to respond. The sheriff then told Clarke County Central Dispatch that he would monitor the radio closely for updates. About 10:48 a.m., Clarke County Central Dispatch had not received a response from the Theadville Volunteer Fire Department acknowledging the page that had been placed about 4 minutes earlier. Clarke County Central Dispatch then repeated the page, this time to the Theadville, Quitman, and Carmichael Volunteer Fire Departments and the Desoto Fire Department. About 10:55 a.m., the Clarke County Central Dispatch dispatcher had not received any responses acknowledging his pages to the four fire departments, and he began to suspect that the fire department radio signal repeater was not working and that none of the pages to the fire departments had been transmitted or received. Therefore, following the Clarke County Central Dispatch backup communication plan, the dispatcher switched to the Clarke County Sheriff’s Department radio signal repeater, which was operating correctly.6 Concurrently, the Clarke County sheriff continued monitoring his service radio and did not hear any responses to the Clarke County Central Dispatch pages. The sheriff suspected that the fire department radio signal repeater had failed to transmit, but he was unable to contact Clarke County Central Dispatch because of the range limitations of his service radio. Accordingly, about 10:55 a..m., he contacted a deputy who was within transmission range and directed the deputy to notify Clarke County Central Dispatch that the radio signal repeater appeared not to be working and to use the Clarke County Sheriff’s Department radio signal repeater to establish radio communications with the fire and rescue agencies. The sheriff then drove his personal vehicle to the site. Accident Site The pipeline rupture occurred in a cattle pasture in a relatively unpopulated area in Carmichael, Mississippi, which is an unincorporated section of Clarke County. The site was occupied by livestock at the time of the rupture. Clarke County has a population of 21,979 and an area of about 416 square miles. The accident site is about 12 miles southeast of Quitman, the Clarke County seat, about 3 miles north of the Wayne County line, and about 3 1/2 miles west of the Alabama-Mississippi state line. (See figure 1.) About 200 residents live within a 1-mile radius of the accident site. The pipeline right-of- way in this area is oriented generally southwest-northeast. The ground rises slightly to the east and west of the rupture site, such that the rupture site is located at the base of a shallow valley. The pipeline is flanked on both sides by uncultivated fields and wooded lots. A 100-foot-wide 6 The Clarke County Fire Department and the Clarke County Sheriff Department can transmit and receive on each other’s radio signal frequency. 6 <<>> NTSB Pipeline Accident Report zone in the middle of the right-of-way had been cleared of trees and shrubs. Federally required warning markers were located along the right-of-way to alert the public to the pipeline’s presence and location, the product being transported, the identification of the owner/operator, and emergency contact information. The buried Dixie pipeline crosses several feet above an 8-inch-diameter hazardous liquid (crude oil) pipeline operated by Hunt. The two pipelines cross about 170 feet east of the northeastern end of the ruptured pipe joint. Hunt representatives told National Transportation Safety Board (NTSB) investigators that the Hunt pipeline was neither involved with nor affected by the rupture of Dixie’s liquid propane pipeline. The Dixie pipeline passes beneath County Road 621 about 900 feet southwest of the ruptured pipe joint. A cluster of six houses is located about 500 feet southwest of the rupture site, with an additional cluster of five houses located a short distance farther south. All 11 houses are on County Road 621. On-Scene Response Upon hearing the explosion and seeing the fireball and heavy black smoke, at 10:43 a.m., the CVFD assistant chief drove his personal vehicle in the direction of the smoke to see the situation firsthand. While en route, the assistant chief spoke to the CVFD chief using his personal cell phone, which had a short-range wireless communication feature similar to a walkie- talkie. The two conferred briefly about what had occurred, made a preliminarily identification of the location sufficient to direct CVFD resources to the general area of the accident, and agreed to mobilize the CVFD in response to the accident. The assistant chief then drove toward the CVFD fire station and used the short-range wireless feature on his cell phone to tell several other CVFD personnel what had occurred and to direct resources (two tanker trucks) to the scene. A few moments later, the assistant chief and the CVFD captain arrived simultaneously at the CVFD fire station. They left immediately in a pumper truck and unsuccessfully attempted by radio to contact Clarke County Central Dispatch to report that they were en route to the scene. About 10:55 a.m. the assistant fire chief and the captain received word that the fire department radio signal repeater had apparently malfunctioned, and in accordance with the back-up communication plan, on-scene fire and rescue units were to switch to the Sheriff’s Department radio frequency that used the sheriff’s department radio signal repeater. About 10:56 a.m., Clarke County Central Dispatch received a message from one of the on-scene deputy sheriffs reporting that the CVFD pumper truck with the CVFD assistant chief and the CVFD captain aboard, had just arrived at the scene at the intersection of County Roads 620 and 621, that the CVFD pumper truck was the first firefighting apparatus at the scene, that the CVFD had already begun to dispatch additional CVFD resources to the scene, and that the instruction to switch to the sheriff’s department radio frequency had been received by the CVFD. 7 <<>> NTSB Pipeline Accident Report About 11:15 a.m., the Clarke County sheriff arrived at the intersection of County Roads 620 and 621, which later became the incident command post location. As prescribed by the Clarke County emergency management plan, the sheriff proceeded to implement an incident command process and assumed the role of incident commander. Later the incident command structure was elevated to a unified command system. When the assistant fire chief and the fire captain approached the scene and saw a substantial fire and a cloud of heavy black smoke, they strongly suspected that the likely source of the fire was the propane pipeline buried underneath the cattle pasture. At the time, they did not know the extent of the fire and the number and locations of residents who might be endangered. Both recognized that the houses on County Road 621 would probably be in the greatest danger, so they drove the fire truck toward those houses. The CVFD assistant chief stated during postaccident interviews that although he was aware that the pipeline transported highly flammable propane, the cause of what appeared to be a substantial rupture and product release and a fully involved fire, and the extent of damage to the rest of the pipeline, were not apparent to him at the time. Accordingly, the assistant chief drove the pumper truck on County Road 621 and stopped just short of the location where the Dixie pipeline passed beneath the road. The pumper truck was initially staged at that location, which became the initial forward command staging location. Additional fire and rescue units from other local fire departments were later staged at the parking lot of the Baptist church at the intersection of County Roads 630 and 632. Responding units from Alabama were staged on County Road 630 at the Alabama state line, and responding Wayne County resources were staged on County Road 620 at the Wayne County line. When the assistant fire chief and the fire captain performed their initial assessment of the situation, they observed several civilians, whom they assumed to be residents of County Road 621 or 620, assisting others to leave the scene. Several sheriff’s deputies arrived about that time, and they also began to assist civilians to leave the scene and to establish motor vehicle traffic control at the west end of County Road 621. A short distance to the east, CVFD personnel observed the burned remains of several houses and several other houses that were fully engulfed in flames and thus were deemed not salvageable. Fire had extensively charred the trees and - **truncated:** true - **body characters:** 157908