Newspaper article St Louis Post-Dispatch (MO)

Leak in Sewer Main Gets Rap for Natural-Gas Explosions State Report Urges Steps to Prevent Another Accident

Newspaper article St Louis Post-Dispatch (MO)

Leak in Sewer Main Gets Rap for Natural-Gas Explosions State Report Urges Steps to Prevent Another Accident

Article excerpt

A leaking, century-old sewer main probably was the main contributing factor leading to natural-gas explosions that destroyed two buildings in St. Louis last November, a state investigative report says.

The Missouri Public Service Commission, in its report, urged Laclede Gas Co., the Metropolitan St. Louis Sewer District and the city to compare their pipe networks for other possibly dangerous intersections.

"We don't know of any others, but we're concerned that other situations like that could exist," John Kottwitz, an engineer for the commission, said Wednesday.

Five people were injured in the two explosions and gas-fed fires. The first occurred at 5:25 a.m. Nov. 4 at a duplex at Steins and Water streets, in the Patch neighborhood of St. Louis. The second explosion, a half-hour later, destroyed an auto-parts store two blocks away on South Broadway.

Crews later found a break in an 8-inch high-pressure gas main buried about 4 feet beneath Steins.

The state report, issued May 23, seeks to explain the break at a weld in the high-pressure gas main, which serves industrial customers. In summary, the report says:

Cracking and buckling of the brick sewer main, which is deeper than the gas pipe, allowed water to leak into the soil around it. That slowly eroded the soil, creating underground cavities.

Six breaks since 1983 in a city water main nearby also contributed to soil erosion, as did the unusually high underground water table during the flood last summer. Kottwitz said the sewer erosion may have contributed to the water-line breaks.

The erosion and pressure from steady truck traffic slowly pushed the gas pipe deeper underground. That bent the pipe and stressed a weld point, which broke a short time before the explosions.

Gas entered the sewer system. It got into the duplex at 126 Steins through foundation cracks or the basement sewer lateral. It probably entered the auto-parts store at 7702 Broadway through the basement laterals.

Something ignited the gas. …

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