Posted: November 01, 2010
Flowing uphill: Aurora’s Prairie Waters project
It reflects the new era of fighting gravity to pump water to homes and businessesAllen Best
If you ever tried to walk up a trail with 1,000 feet of vertical gain, then you have an idea of what Aurora's new water supply must do. To defy gravity, the Prairie Waters system requires energy - lots of it.
Pumping begins at the 17 wells scattered along the South Platte River between Brighton and Fort Lupton. Lined by cottonwood trees, the river there loops back and forth. Among these loops are the wells, 300 feet from the river and about 50 feet deep. The collected water is then pushed uphill at three pumping stations along its 34-mile journey to Aurora.
In Aurora, the water undergoes a four-step purification process. One of them, advanced ultraviolet oxidation, requires particularly large stores of energy. Finally, the water is mixed with Aurora's more bounteous mountain sources for delivery to consumers.
This incessant need for energy by the $655 million Prairie Waters project reflects a growing theme for communities along Colorado's Front Range. The era of gravity-flow water delivery systems from nearby mountain rivers has been giving way to the era of pumping. In a figurative sense, it has long been said that water flows uphill to money. Now, that's becoming literally true.
Colorado Springs also has uphill plans. Located at an elevation of 6,000 feet or more, with not much above it other than Pikes Peak, it has no river to draw on save spindly Fountain Creek. It exhausted that resource decades ago, turning first to water imported from near Breckenridge and then, in 1967, from the Vail-Leadville area.
Now, it will soon break ground on its long-discussed $880 million Southern Delivery System. Water will be drawn 62 miles in a pipeline from Pueblo Reservoir to the city, gaining up to 2,300 feet when distributed to the loftiest neighborhood, Northgate. Additional expansions remain possible.
John Fredell, Southern Delivery System project manager, says annual pumping costs could eventually reach $7.4 million with additional phases. Yet a rigorous review of alternatives by utility officials concluded that even so, it was the most cost-efficient way to deliver new water to the city of 414,000 people.
Other projects, still conceptual, also call for long pipelines with uphill trajectories to the population-rich, water-poor Front Range. One idea envisions a pipeline from Blue Mesa Reservoir near Gunnison, and another from west of Craig. Yet two more see water being imported nearly 400 miles from the Green River in Wyoming or Utah. And, although it isn't clear that Colorado still has the water, the idea of a giant pipeline from near Grand Junction isn't completely dead.
No matter how you cut it, costs of water - surely one of Colorado's great bargains in the last century - will be rising.
"Generally, we agree that the days of cheap water are over," says Stacy Telling- huisen, of Western Resource Advocates, an environmental organization. "Cities looking to develop new water supplies are having to look further afield, either to rivers or reservoirs, or to groundwater aquifers that are deep, or by treating water to higher standards. All take energy."
But Prairie Waters also marks a second and equally important change in Colorado. Very fundamentally, it reuses water from the metropolitan area's wastewater treatment plant. The plant processes sewage for 1.7 million people in the metro area, including Denver and Aurora. Aurora does not take water directly from the river, but rather the water after it has migrated through associated river sands seven to 10 days before reaching the wells.
This process, called riverbank filtration, which is widely used in Europe, further cleans the water. By the time the water gets to Aurora's wells, 99 percent of caffeine and 95 percent of ibuprofen have disappeared.
Aurora is not the first to reuse treated water. Even Breckenridge and Beaver Creek are downstream from other users. What's new is the deliberate reuse of water. Denver pioneered this several years ago, using treated wastewater to irrigate parks and ball fields. Prairie Waters ups the ante, reclaiming wastewater for municipal drinking supplies.
This represents a major potential source of water for the metro area. Colorado water law doesn't allow all wastewater in the South Platte to be reclaimed, but it does for those waters that have been introduced into the Platte River by diversions from the Western Slope. In Aurora's case, that's 40 percent of its existing water supply, and Prairie Waters represents just a fraction of the potential. In a sense, the metro area can recycle its water, losing some every time, but continuing in a diminishing loop to what the law calls "extinction."
Aurora has gone to great lengths to deliver this reclaimed water to customers without taint of any kind. Gregory Barnes, manager of Aurora Water Public Relations, says the city was motivated to avoid perceptions, what has been described as the "yuck" factor. But the higher treatment also anticipates future federal water standards.
This treatment is done on Aurora's southeastern flank, near Quincy and E-470, at the new Peter D. Binney Water Purification Facility. The plant is widely regarded as the most advanced in the region, if not the nation. The South Platte water undergoes four distinct processes: softening, advanced ultraviolet oxidation, granular filtration and activated charcoal adsorption. In a final touch, the water is mixed with that obtained from mountain sources. Nobody should be saying "yuck." But it all takes energy.
Energy intensity in water isn't altogether new in Colorado, of course. Farmers have been pumping from wells since the 1930s. Parker, Castle Rock and other communities between Denver and Colorado Springs notoriously rely upon water pumped from aquifers. Aurora and Colorado Springs have been pumping water from the Homestake project since 1967, with monthly electrical bills for its giant Otero pumping plant near Buena Vista costing $500,000 per month during peak runoff.
Prairie Waters contrasts sharply with Denver's imports from the Western Slope of the last 75 years. Tunnels allow massive diversions from first Grand County and then Summit County to flow downhill to the metro area. Two other major projects constructed in the mid-20th century - the Colorado-Big Thompson and the Fryingpan-Arkansas Project - also rely on expensive tunnels but cheap gravity flow.
Bucking that trend were the South Metro communities that took the temporarily cheaper but long-term risky strategy of pumping water from aquifers containing water residual from the last ice ages. These pumps need enormous amounts of energy.
Western Resource Advocates' Tellinghuisen has studied the energy intensity of water from several of the Front Range cities. Her figures, presented at a recent conference, illustrate the sharp differences. Denver comes in lowest, at 230 kilowatt-hours per acre-foot.
"You won't find any water systems that use less energy than that," she says. Denver has only one small pump in its vast infrastructure aside from neighborhood distribution boosters. The high-quality mountain water needs little treatment.
In comparison to Denver's 230 kilowatt-hour per acre-foot, Aurora's Prairie Waters will likely need 1,200 kwh per acre-foot, from the best information Tellinghuisen was able to obtain. Various longer-distance pumping plans would have an energy intensity of 2,500 or more kwh per acre-foot.
Pumping groundwater in the South Metro area has an energy intensity of 3,000 kwh, Tellinghuisen estimates. That figure will almost surely rise as diminished aquifers become more stingy. Colorado Springs' new water deliveries, however, will be highest of all, 4,500 kwh.
Energy costs already rank as the
second highest cost for utilities. And, as Tellinghuisen notes, energy will almost certainly become more expensive.
Aurora officials were not forthcoming with details about energy use for this article. Instead, they emphasized the efficiency of the pumps and the efforts to
build in renewable energy. The closest to an admission of the energy intensity came in a November 2007 story in the New York Times Magazine, which said that pumping water from Prairie Waters will "cost a small fortune." The source for that statement was Peter Binney, then the head of Aurora Water and the mastermind of Prairie Waters.
Binney, who retains the charming accent of his native New Zealand, arrived at Aurora Water in 2002. That's the year drought stole in on hot spring winds in Colorado, eviscerating an already thin snowpack. An exceptional spring snowstorm in March 2003 delivered a temporary reprieve. But Aurora's vulnerability was evident. At one point, Aurora's water supplies were reduced to nine months, not the five years that Binney considered prudent. Aurora warned residents that outdoor water use might have to end altogether.
That brush with crisis provoked Aurora to take significant steps to suppress demand. It adopted an incremental rate structure to discourage high-volume water use, offered rebates for water-efficient infrastructure within homes, and even launched a "cash for grass" program that rewards homeowners for removing turf.
These efforts have not gone unnoticed. A survey of 13 Front Range cities by Western Resource Advocates in 2007 put Aurora highest in conservation. "In general, new homes in Aurora use much less water than homes in other communities, because of the regulations they have in place," says Drew Beckwith, the group's water policy analyst.
But Binney saw need for a new supply - and he wanted it quickly. Although Aurora has additional water rights in the Vail-Leadville area, such a project would have taken time and perhaps even more expense to provide storage for spring runoff of snow. Binney's idea of reuse, if still enormously expensive, avoided federal lands and hence the review process mandated by the National Environmental Policy Act. From city council approval in 2005, the project has taken just five years. In contrast, Colorado Springs' Southern Delivery System started in 2002 and still needs permits, with completion expected in 2016.
Aurora describes Prairie Waters as a "drought hardening" project as well as supply for continued growth. With reservoirs brimming and real estate development slumming, it doesn't need the water now. But the system can be expanded - and there might be a market for the added water. The 17 well fields could be expanded to 42, allowing Aurora to take advantage of its full "to extinction" reuse water and possibly some of Denver's. The Prairie Waters project, now configured to handle up to 10,000 acre-feet, or about a fifth of the city's annual needs, could be expanded to process up to 50,000 acre-feet - with just one pipeline. The right-of-way along E-470 has room for two five-foot-diameter pipelines.
South Metro communities are the likely market. Representatives of 12 of the cities and special districts in that area have been negotiating with Aurora and Denver about a potential reuse system. Mark Pifher, who replaced Binney as head of Aurora Water, says the agreement has been reached in principle and is now being reviewed by legal teams. The Colorado River Water Conservation District seems to be less directly endorsing the deal.
Aurora insists it doesn't need to sell Prairie Waters water to pay for the project. But Pifher says "regionalizing the resource" only makes sense. "At some point - and as a nation we are rapidly reaching that point - we need to think more regionally and more watershed-based," he says. It makes no sense, he says, for everybody to have their own wells, pipes and treatment plants.
South Metro has the storage for this added water, first in Parker's Rueter-Hess Reservoir, originally designed to hold 16,500 acre-feet and now being expanded to 70,000 acre-feet. But a second idea is to inject water pumped uphill from Brighton into the aquifers from which the South Metro communities now get their water, a process called conjunctive use.
The idea is that Aurora - and perhaps Denver - can sell reuse water from the Platte River wells to South Metro, allowing South Metro perhaps to buy several decades of time. Rod Kuharich, executive director of the South Metro Water Supply Authority, says that a $500,000 study just getting started will examine implications for water quality. More energy yet might be necessary.
The idea has obvious appeal. Aurora and Denver can help provide water to the South Metro communities in ordinary times, weaning them off their wells. Then, during times of drought, the South Metro communities could return to well water. It would elevate Aurora as a water provider in the metro area and also buy time for the South Metro communities to figure out their future.
Taking the long view, Dave Little, Denver's director of water planning, says some water supplies remain that could deliver water by gravity flow to the metro area. But political and environmental consequences of those projects dim their attractiveness. "The ability to tap additional gravity water is becoming as expensive as the pumped water, or maybe more so," he says.
But should conservation itself be pushed even harder? That's the contention of environmental groups, and it's also the conclusion of Douglas Kenney, director of the Western Water Policy Program at the University of Colorado's Natural Resources Law Center. In a new study called "Relative Costs of New Water Supply: Options for Front Range Cities," he examined the cost per acre-foot of alternatives. Conservation strategies came in cheapest every single time.
So why don't cities push conservation harder? Kenney sees cities pushing to build new projects, trying to lay claim to the final drops of water available to Colorado under its various interstate compacts.
"There is only a finite amount of ‘unused' water left for development in new projects, and the cities that act first will secure the majority of that water," he writes. "Savings achieved through conservation, in contrast, is water that the utility has ‘in their back pocket,' available for development at any time without fear of competition from other utilities."
Kenney's right that these projects - $655 million for Aurora and $880 million for Colorado Springs - cost huge amounts. Whether they're visionary, even brilliant, or merely bureaucratic empire-building will not be clear for a number of years.
What is clear enough, however, is that the days of cheap, easy water are gone.