Explosive levels of methane in sewers beneath Milwaukee's Third Ward earlier this month prompted an evacuation of a restaurant and an ongoing emergency declaration from the Milwaukee Metropolitan Sewerage District, according to newly released documents.
An emergency allows MMSD to sidestep the usual mandatory bidding process and hire a contractor to install a temporary ventilation system in a massive underground chamber at the junction of two regional sewers, according to documents released Tuesday in response to a records request.
The ventilation unit will prevent a recurring explosion hazard, officials said.
MMSD Executive Director Kevin Shafer says in an
emergency declaration distributed to the district's commission that high levels of explosive gases in the chamber pose "a greatly increased risk of a spark causing an explosion."
The chamber, or vault, beneath the 600 block of E. Erie St. is about the size of a small house. It is located next to a popular recreational trail and public fishing access on the Milwaukee River and is a stone's throw from the Marcus Amphitheater at the Summerfest grounds.
Two construction cones mark a manhole cover above the chamber, just steps from the entrance to Milwaukee Sail Loft Restaurant at the south end of the street. Letters painted on the street identify the location of a "valve chamber."
Fire trucks arrived on the street in front of the restaurant shortly after 8 p.m. Oct. 2 in response to a complaint of methane gas. We Energies earlier in the evening had determined the gas was not from one of their natural gas pipes and suggested the fire department call MMSD.
An MMSD engineer had met with We Energies before 5 p.m. that day. Dangerous levels of explosive gases were not detected at the time and he left the scene, officials said.
When fire department vehicles arrived after 8 p.m., assistant restaurant manager Brandon Balaka walked outside to ask firefighters if his customers and employees were in danger, he said. He was told no.
About 30 minutes or so later, "they must have changed their mind because they came in and suggested we close," Balaka said. "It was done as a precaution."
A few minutes after the evacuation, at 8:48 p.m., a Milwaukee Fire Department incident report indicates explosive levels of methane were detected at street level at the manhole. Police officers blocked off the street and the fire crew requested the department's hazardous materials team.
At 8:58 p.m., an MMSD representative notified fire officials that Veolia Water Milwaukee, the private company under contract to operate district facilities, would send a crew to the scene.
The hazardous materials team confirmed methane levels were at the upper explosive limit of 15% in air by volume at the street above the sewer, and another fire engine was called to the scene. Methane is combustible at concentrations between 5% and 15% in air. [...]
