Leachate pumping to Resume After Dangerous Levels of Bad Egg Gas

Will Ashenmacher Duluth News Tribune
Published Friday, March 28, 2008

A landfill pumping system that sent dangerous levels of hydrogen sulfide into the Superior sewer system in November will be turned on again today for the first time in five months.

The leachate pumping system, which removes liquids seeping through the Lakehead demolition landfill in the Village of Superior, forced the evacuation of about 20 South Superior homes on Nov. 8. Four men died in the same landfill when they entered the pump Nov. 1 and were overcome by a toxic buildup of naturally occurring hydrogen sulfide gas.

At a meeting Thursday, Superior city officials insisted precautions had been put in place that will prevent an incident similar to either accident from happening again.

Sean Hancock, a project coordinator with the environmental services division of Superior Public Works, said the leachate now will be treated in the pump itself, so no hydrogen sulfide gas should ever enter the sewer system.

Robert Tibbets Jr., who worked on Lakehead’s pump treatment system, said a chemical treatment inside the pump should immediately neutralize any hydrogen sulfide gas, which occurs as a byproduct of bacteria digesting organic matter.

Hancock also said a built-in monitoring device will automatically shut the pump off if hydrogen sulfide levels accumulate above 9.5 parts per million, which is .5 parts per million below the level considered dangerous for short-term exposure. The device, which operates 24 hours a day, also will automatically call a landfill staff member if buildup reaches 9.5 parts per million.

Since Nov. 9, Lakehead has been transporting about 4,500 gallons of leachate a day to Superior’s wastewater treatment plant by truck. The chemical treatment and alarm systems were installed in December and will go into use today, when the leachate will start directly entering the Superior sewer network again.

“By having it come to the sewer system, I’m extremely comfortable that it’s … being treated safely,” Hancock said. More...