From the Aspen Daily News (Collin Szewczyk):
Through a program by the Roaring Fork Conservancy, a group of over 20 people seeking to quench their intellectual curiosities concerning the city’s water, how it’s treated and where it comes from, toured the city of Aspen’s drinking water treatment facility this week led by water treatment supervisor Charlie Bailey and Laura Taylor, an operator at the facility.
Christina Medved, watershed education director of the Roaring Fork Conservancy, pointed out the parameters of the Roaring Fork watershed, noting that local rivers and streams are fed from an area the size of a small Eastern state.
“Our watershed is about the size of Rhode Island,” she said. “And over 30 percent of it is in designated wilderness areas.”
She praised the relationship that the conservancy has with local government entities such as the city water department, that allows visitors to check out local facilities, which are normally closed to the general public.
“What’s really exciting is we get access to places like this,” Medved said. “We have really wonderful partners that will say, ‘yeah, we’ll open up the gate for you,’ when you normally can’t get in here and have an audience with Charlie and Laura because they’re busy bringing water to Aspen.”
Aspenitus
The plant was completed in December 1966 after Aspen endured a major waterborne epidemic of giardia in the mid-1960s. Giardia is a microscopic parasite that is found in soil, food or water that is contaminated with feces. Another parasite, cryptosporidium, has yet to appear in the Aspen area.“That was 1964-65; it was the first documented public health problem in the United States,” said Bailey. “There was a documented waterborne problem and that was giardia. There were two redwood tanks up on the hill here that were used for the hydro plant that was down the street, but the Aspen Water Company provided water to the pipes and there was no treatment at all … It was a big hit, they called it ‘Aspenitus.’”
After the outbreak, the city got money together, bought bonds and broke ground on the treatment plant in 1965. There’s been no cases of giardia in the city’s water since the building of the facility, Bailey said.
“There’s lots of giardia in the water and none of it comes out of the pipeline here,” he said. “We’re required to do testing once a year on the performance of our filters and our clear well (a reservoir used for storing filtered water, which flows through a series of baffles, allowing contact time with chlorine for disinfection).”
Beavers were the main culprit for the giardia epidemic, and the area up Maroon and Castle creeks was teeming with them at the time.
“There was a huge beaver population up there,” Bailey said, but added that it’s good to have them in the area. “They’re animals that let us know that the environment is healthy.”
The water plant also checks the water for mining tailings and other non-natural pollutants.
“We’ve requested extra testing of our water sources,” Bailey said. “We’ve done heavy metal testing and we actually do [pharmaceutical] testing, too.”
He added that no traces of either have been found in Aspen’s drinking water.
“Ever since I’ve been here, and even before, there’s been no problem with city water,” he said. “No public outbreaks, no boil orders, because I will not let it happen on my watch.
“We make the water, and the best thing about making the water here is that it’s clean,” Bailey continued. “The water comes from wilderness areas and there is nobody up above us that has dumped back [into the creeks] after industrial processes or anything like that. We get water coming through the geology, through the snowmelt, we are stewards of the water so we really keep track of everything above us and below us.”[…]
The water here is pumped in from Maroon and Castle creeks and begins its journey through the treatment facility and into Aspen taps. He noted that the city has water rights of 142 cubic feet per second (cfs) in Maroon Creek and about 90 cfs in Castle Creek, even though the streams only hit that level during spring runoff…
The purification process
The reservoir, which holds about 4 million gallons in the summer, is the first stop in the purifying process as sediment in the water begins to settle here.“This is one of our processes,” Bailey said. “We basically bring the water in here and we slow it down. This helps so much during [peak] runoff … the dirt is tumbling, it’s coming in and all the sudden it settles out here and we’re able to draw off the surface and it’s much, much cleaner.”
He added that the water is usually at about one turbidity unit (TU) — the measurement of cloudiness caused by particulates — when it enters the reservoir. When it leaves it’s at .5 TU; during peak runoff it can be as dirty as 60 TU.
“We get reduction in here,” Bailey said. “That’s just a natural tumbling process, we slow it down and that stuff just falls out.”
The nutrient-rich sediment has to be periodically dug out, but it gets spread around the site making the soil perfect for plant growth.
To the north side of the reservoir lies the remnants of the old Maroon Creek flume that was used to divert water to the “tent city” in the late 1800s. As the group was looking down on the wooden channel one observer noticed a bear hanging out in a nearby tree, adding to the natural feel of the site.
The water next goes into large flocculation tanks — which look like UFOs — that, with the aid of chemicals, coagulate the particulates, churn them about and make the sediment again settle to the bottom.
After settling twice, the water makes its journey to a filtration section of the facility. Here, it’s pushed by gravity through a filter that consists of 18 inches of anthracite (coal) and a foot of sand. It next heads to the clear well for 14 to 15 hours to ensure all giardia is killed.
The state’s regulation allows for drinking water to reach one TU and still be acceptable to drink, but on this day Aspen’s drinking water was a pristine 0.037 TU.
More water treatment coverage here.