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  23 September 2017  |  Vol: 4 facebooktwitterrss  
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Where our water comes from, Part II
 

"Right here, a 42-inch pipe starts," says Rick Moroney, City of Bozeman's water treatment plant superintendent, gesturing to the hard-packed ground. Buried beneath our feet, here at the mouth of Sourdough Canyon, is where more than three-quarters of Bozeman's municipal water flows from Hyalite and Sourdough creeks into the city's main water treatment plant.

Rick has worked here since 1984, when the old Sourdough water treatment plant started operating. That plant served Bozeman well, treating as many as 13 million gallons on one summer day, but as new federal water regulations stretched the plant's capabilities, and the spread of homes—and pipes—across the valley showed few signs of easing, the plant's days were numbered. "Now it's gone," Rick says, looking to the scraped lot where the plant used to be. (Photo of Rick Moroney, below, taken at Hyalite Creek.)



A stone's throw away is the new water treatment plant, a $40 million facility that broke ground in 2011. As crews labored over the 43,000-square-foot building, full of offices and equipment, the old plant chugged along. Then, on March 12 of this year, without much fanfare, Rick and his crew flipped the switches, and water began coursing through the new plant on its way to Bozeman's faucets.

The water has already had quite a journey to get here. High in the Gallatin Range, rivulets of snowmelt or small torrents of thunderstorm runoff have cascaded to the belly of the bigger drainages. Hyalite Creek is stalled by a wall of earth at Hyalite Reservoir, where the dam tender crawls into a hatch and cranks a wheel, opening a valve 130 feet below to regulate the flow. Rushing toward bigger waters, Hyalite and Sourdough creeks descend on the valley. Then, part of each is tricked into flowing through grates, screens, and the darkness of pipes, here to where we stand.

Rick leads me across the lot, tracing the underground path of the big pipe to where it enters the new plant. Stepping inside, there's the whir of machinery and giant trunks and branches of pipes. We climb a walkway to see where the water emerges into a concrete basin, forming a deep pool that looks like the lair of a lunker brown trout. This is the raw water, greenish-brown with bits of forest floor and stream silt, thriving with microscopic giardia and other microorganisms intent on roiling mammalian bowels. Thus begins the process of stripping from the water nearly everything but the water molecules themselves.

The first step is to remove the sediment. Rick shows me a metal cone, some 10 feet in diameter at the top, where a propeller spins the water. The propeller pushes the heavy grit outward, where it hits the cone and slides to the pinch at the bottom to be piped away. This is an improvement from the old plant, helping the plant cope with bursts of muddy water from thunderstorms or the occasional landslide into one of the creeks. It would also help the plant cope with the heavy runoff that could result from a wildfire in the 84 square miles of watersheds that feed the plant. "It doesn't mean that we're not worried about fire," says Rick. The city has partnered with the U.S. Forest Service in a plan to selectively log and burn more than seven square miles of the two watersheds—though the effectiveness of this sort of treatment at reducing sediment runoff is still up for debate. Anyway, the plan is jammed up in federal court, part of a larger dispute over critical species habitat (in this case lynx habitat).

The next step is to remove the organic material and finer sediment—tiny bits of soil, moss, elk scat and the like. Blender-like mixers inject a chemical that helps the tiny particles bind together, and the water is then gently stirred by slowly turning paddle wheels in a series of concrete tanks. As Rick leads me down the row of tanks, I peer into the green water where a shaft of sunlight pierces from a skylight above, and I see the suspended, coagulated particles. This is just before the water flows into a grill of angled metal plates where the particles settle out, forming a sludge that's collected and dried on an acre or so of long beds outside (photo, below) and then scooped up and taken to the Logan Landfill.



At this point, most of the suspended matter in the water has been removed, but microorganisms and other impurities remain. So the water is piped to another vast room and pumped through membrane filters. The membranes (photo, below) are housed in several racks of more than 120 tubes, each nearly ten feet tall. Inside the tubes are hundreds of hollow spaghetti-like plastic strands, perforated with pores 500 times smaller than a human hair. The pressurized water passes through the pores, leaving behind giardia and other microscopic bits. As we walk down the lines of tubes, Rick recalls how the water treatment crew, before the new plant came online, practiced detecting and patching tiny leaks in the membranes: they would hunt down the faulty tube by pressurizing the system, then find the leaky strand by tracking tiny bubbles, then pinpoint and patch the tiny leak.



The water's journey through the plant is nearly finished. In another concrete tank, pipes inject chlorine, which kills remaining viruses in about ten minutes, along with sodium hydroxide, which neutralizes the water's slight acidity and prevents it from dissolving lead or copper in household pipes. Finally, in a small underground reservoir, just before the water rides gravity toward town, fluoride is added.

The work of the water treatment crew, however, doesn't end here. Rick leads me through the plant's control room and into a lab, where a lab tech is busy over vials of water samples. He collects samples from seven places in town—Motel 6, K-Mart and others—every single day of the year, testing them for any impurities. Sometimes it's hard to find places that are open on Christmas, he says.

Rick chimes in, estimating the number of tests per year at about 15,000. We're in his office now, where a map tacked to the wall shows the Hyalite and Sourdough watersheds nestled in the Gallatin Range, miles from the nearest farm or factory. "People who move here from other places call me up and say, 'Come on, tell me what's really in the water!'," he says. "And I get to say: 'Nothin'.' "

-TBM

LINK HERE for the complete lising of Marshall Swearingen's six City of Bozeman infrastructure articles, plus his other published features for the Magpie.

 
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