- Associated Press - Monday, May 30, 2016

LEAD, S.D. (AP) - There is a little-known legacy of Lead’s gold-mining era that is - to say the least - less than golden.

It doesn’t smell very good, either.

That legacy is a “combined sewer,” the term applied to a series of pipes that carry both stormwater and sewage to a wastewater treatment plant, the Rapid City Journal (https://bit.ly/1Vi0u2t ) reported.

When the city gets a big rain, the system is overwhelmed by the combined volume of the two water sources. In those circumstances, some of the combined flow - including untreated sewage - is diverted away from the treatment plant and directly into Gold Run Creek, which flows into Whitewood Creek.

The practice is contributing to unsafe levels of E. coli in Whitewood Creek, according to a newly released draft of a biennial state government report on surface water quality throughout South Dakota.

E. coli is a bacteria that can make people sick, and the levels of E. coli detected in Whitewood Creek have caused the state to declare some stretches of the creek too impaired to support “immersion recreation” such as swimming.

The city of Lead has been wrestling with the problem for decades, with oversight by state and federal regulators. Lead is the only city in the Environmental Protection Agency’s six-state Mountains and Plains Region that is formally permitted to operate a combined sewer overflow system.

Lead’s unique combination of rocky soil and narrow streets makes the expensive prospect of separating the city’s stormwater and sewage even more expensive than it would be elsewhere, so regulators have shown patience while insisting on regular progress toward a total separation of the stormwater and sewage.

Over the past few decades, according to Roger Thomas, Lead’s public utilities supervisor, the city has separated 80 percent of the system. That has been accomplished by laying separate underground pipes for stormwater and sewage whenever a street project is undertaken.

Thomas said there is no definitive schedule for completing the final 20 percent of the work. The city will simply continue to tackle it a little at a time, as funding allows.

Thomas did not know how much the city has spent on the project over the years. The state Department of Environment and Natural Resources has records showing that state government has contributed at least $3.5 million in loans and grants to the work since 1990.

Every completed segment of separated pipe has helped reduce the bacteria load released into Whitewood Creek. Thomas said the volume of periodic overflows has been reduced to the point that one of the system’s two diversion structures will soon be eliminated.

“So there’s progress being made,” Thomas said.

He has been dealing with the problem since he started working for the city in 1994. The problem dates to the city’s founding as a Homestake Mining Company town in the 1870s. Thomas said the company built the combined sewer system, apparently anticipating that the town would disband in several decades after the area’s gold was mined. But activities in the Homestake Mine, now known as the “Open Cut,” continued until 2002.

Throughout Lead’s early decades, the combined sewer flowed directly into Whitewood Creek along with millions of tons of mine waste.

“It was called Cyanide Creek in the 1960s and ‘70s,” Thomas said, “because it was black.”

In the 1970s, the newly formed EPA began a long period of investigation, regulation and forced cleanup of the creek’s pollution sources.

In the 1990s, the city of Lead finally took over operation of the combined sewer system and began the long, slow work of separating the wastewater and sewage into separate pipes.

Today, the remaining combined sewer segments are not the only suspected source of E. coli in Whitewood Creek. The draft biennial report on the state’s surface water quality, known as the Integrated Report for Surface Water Quality Assessment, additionally identifies aging septic systems, wildlife and livestock as possible E. coli sources.

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Information from: Rapid City Journal, https://www.rapidcityjournal.com


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