By JOSH MCDONALD,
Let me tell you what, tours can be a journalist’s dream and nightmare at the same time. There’s always so much to look at and never enough time to get every last bit of information.
I had the pleasure of taking a tour of the remodeled Central Treatment Plant a few weeks ago and to infer that what I saw was impressive would be a dramatic understatement.
Replacing a 30-year-old plant is no simple task, especially with how regulations have changed drastically over the years and continue to evolve.
Before I could begin the tour though, I had to undergo a quick safety briefing to ensure that not only was I equipped with the necessary safety gear, but also prepared for any potential situations that may arise on the tour itself.
The Central Treatment Plant (located just North of the Bunker Hill Mine facility) has historically treated contaminated waters from the Bunker Hill Mine. Roughly 1.7 million gallons of water flow from the mine to the plant every day.
The upgraded treatment plant will continue to treat contaminated waters from the Bunker Hill Mine, but will now also handle the water that comes from the newly constructed groundwater collection system along Interstate 90.
The tour began with a quick walk along the old clarifier tank, as my guides Rod Zion with the Army Corps of Engineers, and Ed Moreen, EPA Coeur d’Alene Basin Cleanup project manager, explained how the former system had worked prior to the upgrade that the facility has undergone in the last few years.
They detailed out how water from the Bunker Hill was pumped to the tank directly, or to a holding pond where it would wait until the tank was ready to treat it. The new system, although larger, will work more efficiently and allow for more water to be treated than before.
“Once the upgrades are complete and the new groundwater collection system is online, contaminated waters will enter the plant at the new concrete structure, called a reactor,” Zion said. “Inside the reactor, waters will be mixed with lime, polymer chemicals, and aeration to neutralize the waters and begin the precipitation of contaminants.”
Following the treatment, the water gets moved to the large clarifier tank where the contaminants will settle out and create sludge.
Ed and Rod took me to the top of the reactor, where an observation deck allows onlookers to see everything at the CTP, including the old clarifier tank, the new clarifier tank, the new filter building, as well as the Bunker Hill Mine facility and the top of the neighboring Central Impoundment Area.
I’ll be the first to admit that while heights tend to give me a case of the dizzys and a little bit of the tinglies, the view from above the reactor was a sight to behold.
The combination of historical significance, mixed with the stark contradiction of the progressive new treatment system, was equal parts exhilarating and overwhelming.
The CIA, commonly referred to as the “slag pile,” is the massive repository that lies between Kellogg and Smelterville. As mentioned, the top of the CIA is being utilized as part of the CTP.
The sludge that is formed at the treatment plant is then piped to a newly constructed high density sludge thickener. Then the thickened sludge is conveyed to a newly constructed sludge impoundment area on top of the nearby CIA.
One of the first things I asked during the tour was what they did with the contaminated water that was still flowing out of the mine facility while they demolished parts of the old facility and built the new one.
“During demolition of the old treatment plant and construction of the upgraded treatment plant, contaminated mine waters have continued to be treated in an onsite temporary treatment system,” Zion answered. “The temporary treatment system will be dismantled and treatment operations will be permanently transitioned to the upgraded facility.”
So. If you’re tracking the water from step one, this is where we’re at:
The contaminated water has been treated, the heavy contaminants have been separated into water and sludge, and the sludge has been piped to the top of the CIA. The water now makes its way into the newly constructed filter building. The clarified waters from the clarifier tank move into the filter building where a series of seven filter vessels further clean the waters.
From there, the clean waters are conveyed via a buried pipeline to a newly constructed riverbed embedded discharge at the South Fork of the Coeur d’Alene River.
The filter building also houses the electrical nerve center for the entire plant.
As we made our way through the filter building, I got an up close look at the massive tanks that are used for the filtering process.
The filter building also allows access to the underside of the newest clarifier tank, where I got to see where the sludge is pumped out to the new impoundment area. This was one of the coolest parts of the tour for me because it really showed the level of intricacy that has gone into this project.
The tank itself is a marvel with all of the bolts and the vast amount of water it can hold, but holding it up are several pillars and concrete forms. Each concrete form had to be specifically poured and fitted to the exact spot below the tank.
According to Zion, the new system should be online and operating by the end of February and construction should be fully completed by May 9.
At a cost of $48,633,550, the building contract was also an operator contract, so when Wood Environmental & Infrastructure Solutions Inc. (formerly known as Amec Foster Wheeler) finishes the building of the plant, they will also be the primary operators of it for a full year following completion. The contract is scheduled to be completed on May 9, 2021.
The EPA, and Moreen in particular, is incredibly pleased with the efforts of the Army Corps of Engineers and Wood Environmental for their dedication to the project.
One of the main concerns facing the area is the levels of zinc found in the waters that flow from the Bunker Hill Superfund Site and make their way toward Lake Coeur d’Alene.
“As the newly-upgraded Central Treatment Plant begins final testing and evaluation, citizens of the Silver Valley have a lot to cheer about,” Moreen said. “They are about to witness the spooling-up of a world-class, state-of-the-art water treatment plant that will immediately begin reducing zinc loading to the South Fork Coeur d’Alene River. The plant will play a key role in local water quality protection for people, fish and wildlife. The U.S. Army Corps of Engineers and their contractors really ‘earned their stripes’ on this project.”
According to the EPA, when finished, the groundwater collection system and upgraded treatment plant will reduce the single highest source of dissolved zinc pollution to the South Fork of the Coeur d’Alene River by up to 90 percent.