But you wouldn't have wanted to blink - or you might have missed it.
NorthWestern Energy's Mike Haenke touched off the nearly $100 million project by pushing the green “raise” button on the wall inside the now-quiet Milltown Dam powerhouse.
With that, the permanent drawdown of the reservoir officially began.
Over the next few weeks, the gate will inch up a bit more each day until the reservoir drops by as much as 10 feet. As the pond drains, sediments contaminated with century-old mine and smelter tailings will be exposed - and then, removed.
Eventually, the drawdown will lead to the removal of Milltown Dam itself and restoration of the confluence of the Clark Fork and Blackfoot rivers.
“This is the trigger that starts it all. To us technical people, this event is bigger than the consent decree,” said Russ Forba, the Environmental Protection Agency's Milltown project manager. “It marks the start of the actual mitigation.”
The plan is to drop the reservoir by as much as a foot a day for the first 6 feet. After that's achieved, NorthWestern Energy will slow releases from the dam to ensure the reservoir doesn't drop more than half a foot per day.
The idea is to let the river scour some of the top layer of sediments - those that don't contain high concentrations of heavy metals - during this last half of this year's spring runoff. The EPA estimates that as much as 100,000 tons of sediment will flush down the river during the early portion of the drawdown.
That's not to say that people downstream will likely notice.
The drawdown was timed to coincide with the peak of the spring runoff - a time when the river is naturally turbid. Most of the scouring of sediment in the reservoir should be done by the time the river drops to its normal summer flows.
The EPA and a host of other agencies will keep a close eye to ensure that turbidity and heavy metal levels don't get out of hand over the next few weeks. If levels increase over allowable limits, releases from the dam will be scaled back.
“There will be a lot of monitoring going on,” Forba said. “We don't expect to see any significant impacts.”
“In the long term, the benefits of this project are going to be substantial. There might be some short-term impacts, but we are going to do our best to minimize those,” he said.
Once the drawdown is complete sometime in July, it won't be long before heavy equipment arrives on the scene.
The first actual construction work people will see should start later this summer, when crews begin shoring up bridge abutments and pilings.
The EPA will take the lead on the two Interstate 90 bridges and the state highway bridge. Montana Rail Link is responsible for its bridge, and Missoula County will work on the pedestrian bridge.
People can expect some delays on the interstate starting this fall, when one bridge at a time will be closed for up to six weeks as crews work to stabilize the structures, Forba said.
There is also a possibility that the eastern lanes of I-90 could see some settling as the reservoir drops. That portion of the road is constructed on old sediments that could consolidate as the ground dries, Forba said.
The EPA will also continue to monitor water wells of local residents, which could be threatened by a drop in the aquifer following the drawdown. The agency has already replaced or plans to replace about 11 wells in the area, Forba said.
“The most dramatic impacts so far have been right in Milltown right next to the Blackfoot River,” he said. “There have also been some impacts to wells in the West Riverside area.”
As the reservoir drops, people may see some increased turbidity as their pumps have to work harder to bring water to the surface.
“If people have sediment problems, they should call us,” Forba said.
By fall, Envirocon crews will be busy building a haul road, a rail spur and starting construction of a large bypass channel for the Clark Fork River.
The dam at Milltown is scheduled to be removed in the spring of 2008. Restoration work will continue through 2011. The Atlantic Richfield Co. and NorthWestern Energy are paying for the cleanup, which includes the dam removal and excavation of the most highly contaminated sediments in the reservoir.
Additional information about the Milltown Project, can be found online:
For monitoring data, visit ftp://milltown.envirocon.com.
For site-related design documents, visit http://www.epa.gov/region8/superfund/sites/mt/milltowncfr/home.html, ftp://public:mtpub05@64.25.133.122 or http://www.cfrtac.org.
Milltown Reservoir cleanup timetable
June 1: Stage 1 drawdown, reservoir drops up to 10 feet.
August/September through November 2007: Bridge mitigation work, site infrastructure work begins on haul roads, rail bed and river bypass channel.
October/November 2007: Stage 2 drawdown, reservoir drops 7 or 8 feet, turbines at the dam are removed, cofferdams constructed.
Starting November 2007: Sediments hauled to Opportunity Ponds, spillway removal begins.
February 2008: Stage 3 drawdown, river drops about 13 feet into its new channel.
June 2009: Finish floodplain reconstruction
January 2010: Restoration activities, work completed by 2011.
|
 |
 |
Add your comment now! Write your comment in the form below.
(Email address is for verification only. If you'd like to email a story, look for the link above)