A fire, which ignited Thursday following a blast at Duke Energy’s Moss Bluff underground salt cavern storage facility in Liberty County, TX, just northeast of Houston, increased in size and intensity in the pre-dawn hours Friday when an above-ground valve structure failed, causing a larger release of natural gas that shot flames 1,000 feet into the sky, the company said.
Despite the turn of events, Duke Energy said it expected the fire to “probably burn out” by Saturday when the approximately 6 Bcf of stored gas released from Cavern #1, the suspected source of the explosion, was burned off. The other two caverns at the facility were not involved in the fire. However, all storage service was halted.
The valve assembly collapsed at about 1:30 a.m. (CDT) Friday due to the intense heat from the fire, increasing the release of gas from Cavern #1 that has the capacity to hold up to 8.7 Bcf ( including working and base or cushion gas). The flames soared from 100 feet to 1,000 feet as a result, and were said to be visible from Houston, 40 miles away.
All Moss Bluff personnel on the site were accounted for following the valve failure, the company said. Duke Energy said it recommended to emergency personnel in both Liberty and Chambers counties that a three-mile area around the facility be evacuated. It was assisting local sheriff’s departments Friday in re-locating residents to either shelters or hotels, said spokeswoman Gretchen Krueger.
An investigation into the cause of the fire was underway and damage assessments were continuing, Duke Energy said. The company notified the appropriate state and federal agencies, including the Federal Energy Regulatory Commission, the Department of Transportation (DOT) and the Texas Railroad Commission, Krueger said.
The Texas Railroad Commission is the lead agency in investigating the cause of the explosion, as well as assessing the impact of the blast/fire on the surrounding community and the pipelines that connect to the storage facility, said Damon Hill, a spokesman for DOT’s Office of Pipeline Safety in Washington, DC. But “we are monitoring the situation.”
Firefighters from Boots & Coots were at the scene Friday and taking steps to try and cool the area and cut off gas to the blown-out valving, the Houston Chronicle reported.
The valve failure Friday followed an explosion that jolted the Moss Bluff storage facility early Thursday, sending flames 100 to 200 feet into the sky and forcing the company to curtail service at the facility. No injuries or damage to the area surrounding the storage site were reported as a result of the blast, Duke Energy said.
Initial reports said the source of the explosion, which occurred at 4:15 a.m. (CDT), was in the cavern with 6 Bcf of stored gas. But “we have not confirmed that,” Krueger said. Two other nearby storage caverns at the site were not affected by the intense fire, but all storage withdrawals and injections have been curtailed.
Krueger on Friday said she could not estimate how long service at the storage facility would be interrupted. Extinguishing the fire, assessing the damage and investigating the cause of the explosion were the company’s priorities now, she noted. Duke Energy said it has standard general liability and property insurance and does not expect the blast and subsequent fire to have a material financial impact on the company. The Duke Energy Foundation contributed $10,000 to the Greater Houston Chapter of the Red Cross to help temporarily relocate families affected by the blast.
The throughput on the five pipelines that interconnect with Moss Bluff was not affected by the blast. However, Texas authorities last week were concerned that the heat from the fire could cause connecting pipelines, which are located two to three feet underground, to rupture and ignite, the Houston Chronicle reported.
Pipes interconnecting with the storage operation include interstates Texas Eastern Transmission and Kinder Morgan’s Natural Gas Pipeline Co. of America, and intrastates Channel Industries, Kinder Morgan Tejas Gas Pipeline and Kinder Morgan Texas Pipeline.
The high-deliverability Moss Bluff storage facility serves 13 customers, including marketers, pipelines and local distribution companies, with 16 Bcf of working gas capacity from three caverns. Moss Bluff has a send-out capability of 1.2 Bcf/d, and is ranked 11th in the nation in terms of deliverability.
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