All employers, employees, and contractors within all three segments of the oil and gas industry (upstream, midstream, and downstream) are responsible for ensuring safe and healthful work sites.

The Significance of API RP 2219 Recommendations in the BLSR Accident, Part 1

Employers and workers need to pay special attention to minimum recommended safety requirements of approved standards and safe working procedures.

Noble Energy (formerly Samedan Oil Corporation) was a global oil and gas exploration and production (E&P) company founded in 1932. Noble Energy is permitted by the Texas Railroad Commission (RRC) to operate oil and gas wells in Texas, including the CJ Waller and Roberts leases in Brazoria County, the two well sites involved in this incident. The CJ Waller lease began gas production in spring 2002, and the Roberts lease began gas production in fall 2002. Noble Energy uses contractors to perform daily inspection and maintenance activities as well as to remove and transport condensate, oil, and waste liquids.

Noble Energy also contracts with T&L Lease Services, Inc., to provide various oilfield services, including transport of waste liquids from drilling and production wells to permit waste disposal facilities. T&L Environmental Services (T&L), a subsidiary of T&L Lease Services, is a Texas RRC-permitted oil and gas waste liquid hauler. The company has been in operation since spring 2001 and employs about 15 personnel. Vacuum trucks and drivers are permitted and licensed in accordance with U.S. Department of Transportation (DOT) regulations. Based on T&L regulations, the trucks were not authorized to transport flammable liquids; this was confirmed by truck tank manufacturing records and a manager.

The BLSR operating facility was located 29 miles south of Houston and 5 miles north of Rosharon, Texas. BLSR employed 18 personnel. The facility has been in operation since the mid-1980s and in 2003 permitted by RRC to operate five U.S. Environmental Protection Agency Class II waste liquid injection wells. It operates on a 24/7 schedule. The BLSR disposal facility contains two waste liquid unloading stations—the saltwater disposal station and the mud disposal and washout pad. These stations are used to receive E&P waste liquids, including saltwater, freshwater, used drilling mud, and BS&W (basic sediment and water).

At approximately 4:30 p.m., on Jan. 13, 2003, a vapor cloud deflagration and pool fire erupted at BLSR. The fire was caused by the release of hydrocarbon vapor during the unloading of basic sediment and water from two vacuum trucks into an open area collection pit. Three BLSR employees sustained serious burns; two were transported to Fort Bend County Hospital by private vehicle, and the third was transported to Danbury Hospital by Angleton EMS. Two other BLSR employees standing near the pad were not injured. Two BLSR employees were killed and three were seriously burned. Also, the two T&L drivers were severely burned and flown to Hermann Hospital; one succumbed to his injuries 46 days after the incident. The fire destroyed two 50-barrel (2,100-gallon) vacuum cargo tank trucks owned and operated by T&L and heavily damaged equipment and structures in and around the BLSR unloading pad.

Accident Events
Waste liquids generated at exploration &production sites include saltwater and freshwater, drilling mud, and BS&W, all of which can contain some flammable hydrocarbon liquids and significant volumes of waste liquid, including potentially flammable BS&W.

On the accident day, the temperature was about 50 degrees F, winds were from the west at less than 5 miles per; the combination of these two measurable parameters could increase the possibility of the flammable vapor releasing and moving in on the closest ignition source, if the flash point of the flammable liquid was less than ambient temperature.

BLSR employees were in the process of diluting drilling mud that had accumulated from earlier deliveries by adding clean water and recirculating the liquid through the hydraulic pump and back into the pad area. The two drivers exited the trucks, left the engines running, informed BLSR employees that the trucks were to be drained and rinsed out, and made their way to the drivers' shed to complete paperwork and wait for the washout to be completed. As reported by eyewitnesses, the trucks were in position for 3-5 minutes when the truck engine on the north side began to violently race/rev, slowed, and then violently raced again, blowing thick black smoke from the exhaust stack.

The second (south) truck engine began the same violent racing. At this point, a deflagration occurred. The BLSR employee standing between the trucks reported that the fiberglass hood on the south truck jumped up a few inches. Another BLSR employee stated that it looked like there was a flash of lightning under the south truck. The BLSR owner and two employees in the main office heard what sounded like a muffled explosion and looked out the door toward the processing areas. They observed heavy black smoke at the concrete pad work area. One of them placed a call to 911 at 4:36 p.m. Angleton Emergency Medical Services and the Rosharon VFD arrived on scene at 4:50 p.m.

The firefighters reported an intense pool fire producing a large amount of thick black smoke and very intense heat, with flames 15 feet high. The fire was brought under control at 5:35 p.m. The fire was extinguished within 50 minutes. Two helicopters transported two of the burn victims to a local hospital. The other three victims were transported to hospitals by private vehicle or ambulance.

Emergency responders completed their work at 10:00 p.m. There was no environmental damage.

Because of the deaths and injuries caused by this incident, the U.S. Chemical Safety and Hazard Investigation Board (CSB) launched an investigation to determine the root and contributing causes. CSB investigators arrived at the site on the morning of Jan. 15, 2003. Over the course of the investigation, they examined physical evidence; interviewed Noble Energy, T&L, and BLSR management and hourly employees; visited other oil and gas production wells in the area; interviewed oil/gas producers and trucking company personnel; collected and tested oil/gas well production liquids; and reviewed relevant documents.

The board found inconsistency within the industry in managing the potential flammability hazard of BS&W. In some cases, the flammability hazard is not identified or recognized, and work practices are inadequate for safe handling of the potentially flammable liquid.

The CSB investigation focused on these matters:

1. Determining the level of employer and worker awareness of flammable liquid hazards at oil/gas production wells and disposal facilities. In a 1992 EPA study of 32 production and reclaimer BS&W samples analyzed for flammability, 17 were found to meet the DOT Class 3 flammability criteria (USEPA, 2000; p. 26). Of the BS&W samples tested by CSB and Noble Energy and those documented by EPA, more than 64 percent were determined to meet the DOT Class 3 flammability rating.

2. Characterizing the flammability hazard of waste liquids to identify sources of flammable vapor. CSB analysis of nine tank BS&W samples from six production wells, including one of the wells involved in the BLSR incident, resulted in flashpoints below 30 degrees F in eight of the samples. Tests commissioned by Noble Energy on BS&W samples from the CJ Waller and Roberts leases also resulted in flashpoints below 60 degrees F and 30 degrees F, respectively. (For comparison, the flash point of condensate is about -36 degrees F, and the flashpoint of gasoline is about -45 degrees F.)

CSB determined that a flammable vapor cloud was ignited. There are two scenarios for the source of the flammable vapor: 1) waste liquid offloaded in the disposal pad earlier in the day, and 2) waste liquid delivered by one or both of the T&L vacuum trucks. CSB determined that the T&L trucks were in the process of offloading BS&W onto the concrete pad when the deflagration occurred. The flammable vapor that ignited most likely originated from this BS&W. Meanwhile, it is unlikely that the flammable vapor that ignited originated from the waste liquid remaining in the pad from the earlier deliveries. Meanwhile, physical evidence also showed that the diesel fuel in the tanks did not spill to the pad area or contribute to the pool fire behind the trucks.

3. Identifying the potential ignition source. As discussed below, there were five possible vapor cloud ignition sources: 1) the vacuum truck diesel engine, 2) vacuum truck electrical system, 3) static electricity discharge from the offloading liquid, 4) personnel smoking, and 5) facility electrical wiring, with the  diesel engine as the most likely ignition source, though high-temperature engine components and static electricity discharge cannot be ruled out. The other two possibilities were determined to be unlikely.

Root Causes and Contributing Causes
Based on CSB investigation result the followings are root and contributing accident causes.

1. Noble Energy management did not identify the potential flammability hazard of BS&W, properly class and describe the material, or inform employees and contractors of the hazard. The required MSDS was not provided to the vacuum truck drivers. Condensate storage tanks were not labeled with hazard information.

2. T&L management did not require the shipper to provide the vacuum truck drivers with an MSDS or other document listing the potential flammability hazard of BS&W prior to loading the truck, nor did it identify the flammability hazard of the mixture in the truck tank. Also T&L management did not implement safe work practices (such as those contained in API RP-2219, Safe Operation of Vacuum Trucks in Petroleum Service) to minimize the generation of flammable vapor and to control possible ignition sources when loading and unloading BS&W. T&L treated all waste liquid as nonflammable, as reported by management and evidenced by the use of non-DOT certified vacuum truck tanks. T&L did not inform the drivers that BS&W could present a significant flammability hazard, requiring special handling precautions, such as ensuring that the truck engine was upwind and far enough away to preclude contact with a flammable vapor source.

3. BLSR management did not have practices in place to recognize the potential flammability hazard of each delivered load of BS&W, nor did it implement safe handling practices when offloading.

  • BLSR did not review shipping papers or conduct flammability tests to determine the flammability hazard of delivered waste liquids before offloading.
  • BLSR provided no means of grounding the vacuum truck on the waste disposal pad, an important safety precaution to reduce the possibility of static discharge.
  • BLSR unloading methods did not minimize or control the generation of flammable vapor during the offloading of BS&W; there was no effort to avoid uncontrolled splashing onto the open concrete pad.
  • BLSR and T&L management were apparently not aware of API guidance.
  • BLSR relied on the vacuum truck driver to select the appropriate unloading system—saltwater disposal station or mud disposal and washout pad—without consideration of the potential to generate significant flammable vapor and without adequate driver training on decision criteria.
  • BLSR did not provide appropriate training to employees or truck drivers on the specific hazards associated with unloading flammable liquids, methods to minimize generation of flammable vapor, and ignition sources.
  • T&L and BLSR management failed to train their employees on diesel engine overspeed as an indication of the presence of a highly flammable vapor.
  • The truck drivers and at least one of the BLSR employees responded to the diesel engine malfunction by moving closer to the trucks. If they had remained where they were or moved farther away, they would not have been injured by the fire.
  • There were no emergency procedures for safe and proper response to diesel engine over speed.
  • BLSR management had no written procedures for truck unloading, operation of systems, or emergency response.

As a result of comparing the investigators' findings and CSB advice with API RP 2219 standard recommendations, we find "what went wrong" that brought about the BLSR accident. If we search industrial accidents to find the main causes, in most of the findings there would be at least one common important issue.

This hidden reality is that employers and their employees need to pay special attention to:

a) Minimum recommended safety requirements of approved standards.

b) Providing appropriate training.

c) Preparing a safe working procedure.

This article originally appeared in the January 2017 issue of Occupational Health & Safety.

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