AmerenUE to submit plan for eliminating clay from Black River

AmerenUE must submit a plan Tuesday for restoring the Black River by eliminating the suspended clay and other solids that turned the once-clear stream a cloudy gray.

The change in water quality is one of the lingering effects of the reservoir rupture on Proffit Mountain that sent more than 1 billion gallons of water crashing through Johnson's Shut-Ins State Park. AmerenUE proposed this week to use alum, a chemical commonly used to increase clarity of drinking water, to bind solid particles so they will settle out of the stream.

The Missouri Department of Natural Resources approved the idea after studying the concept, spokeswoman Connie Patterson said Friday.

"We wanted to make sure that adding chemicals to the water was not going to impact water quality in a negative way," she said. "We agree that this is the direction to go, and told them now tell us how you are going to do it."

All 'upfront'

The Tuesday deadline won't be a problem, AmerenUE spokesman Mike McCleary said. Everything the utility company does to improve the water quality will be publicly discussed and safe for aquatic life, he said. "It will all be upfront."

Shortly before dawn on Dec. 14, the northwest wall of the reservoir feeding the Taum Sauk Hydroelectric Plant collapsed. The torrent scoured a 200-yard wide path down Proffit Mountain and into the Black River. When the water reached the bottom of the hill, it hit a home, two trucks and then roared through Johnson's Shut-Ins.

Park officials hope to reopen the park by summer. But the water flowing over the 1.5 billion-year-old rocks in the riverbed remains cloudy, and that could make the natural water park less attractive to the 250,000 visitors who make it a summer playground.

They also want to remove the sediment in order to protect fragile aquatic life downstream from the state park, Patterson said.

"Not only do we have to look at restoring things to what they were before the reservoir broke, we have to see what we have to do to fix any impact as we go along," she said.

The chemical treatment will focus on the water coming down the bare rock out of the reservoir, which was built as a huge bowl on top of the mountain. Future steps must include ideas on preventing erosion that would widen the strip of bare rock exposed as the water drained from the reservoir.

Sagging walls

At the Taum Sauk power plant, water held by a dam along the Black River was pumped to the top of Proffit Mountain, then released through tunnels more than a mile long to turn electric turbines. Preliminary studies have found that the walls of the reservoir had sagged over the years.

The rupture occurred when automated shut-off valves failed, allowing the reservoir to become overfilled. Water then ran over the sides, eroding the earth layer protecting the rock fill and weakening the structure.

A federal agency investigating the failure has not issued a final report on exactly why the reservoir collapsed.

Once AmerenUE submits its plan, it will be reviewed quickly but no deadline has been set for final action, Patterson said. At a large public meeting Thursday evening in Lesterville, area residents showed they were anxious to learn more about what will be done to restore the river and the park, Patterson said.

"We heard loud and clear this is a priority for them," she said.