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: 14500 People by June 1, 2012

Support To-Date: 14247 People (January 15th)

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We need your help. If you want to stop uranium mining in northern Colorado, you must act now.  You can start by signing our petition and voicing your opposition to the Weld County commissioners. See the Stop the Mining menu for details.

Deep Well Injection Print

On January 21, 2009, Powertech Uranium reported, with the completion of a feasibility study on deep disposal injection wells, they had reached a major milestone in their permitting process for their proposed Centennial Project uranium mine in Weld County. “The Company anticipates permitting deep disposal well(s) for the disposal of land and well field waste streams.” (Click here to see Powertech's Management Discussion and Analysis Report for January 22, 2009.)

Disposing of uranium mining’s hazardous wastes through deep well injection is less likely to be disturbed by winds that would effect land applications and evaporation ponds. However, serious concerns surround the intentional contamination of groundwater. In response to the degradation of our nation’s aquifers, the National Research Council (NRC) published a collection of studies of groundwater contamination in 1984 ( Aquifers had been contaminated by the pumping of hazardous wastes below ground in an out-of-sight, out-of-mind mentality. Legislation that restricted air and surface-water pollution resulted in increased disposal of wastes in the subsurface, contaminating aquifers and future water resources.

Powertech has described the ISL process as a new technology for mining uranium, a system guarded by monitoring wells that will detect when a leak or excursion has occurred. In fact, commercial ISL mining for uranium has been in extensive used in the United States since 1975. ISL of uranium, while cleaner than open pit mining, has a history of leaks, spills, and questions surrounding long term restoration and aquifer contamination (see Monitoring wells do not stop contaminates from entering the aquifer, they only detect when an excursion has taken place and signal the possible direction of the contaminate flow.

During the 1970s, companies seeking to cash in on Weld County’s uranium were conducting exploratory drilling within the Centennial project (3,500 drill holes) and around Keota (click here to see Keota uncapped drill holes), and testing an ISL facility near Grover. All three activities were in Weld County’s portion of the South Platte River Basin, a major alluvial aquifer in Colorado.

Map courtesy of Colorado’s Department of Natural Resource’s Ground Water Atlas of Colorado

The Grover ISL test mine was in the Crow Creek drainage, a tributary of the South Platte River west of Sterling, Colorado. One difference between the proposed Centennial project’s ISL operation and Grover’s ISL was Grover’s use of an ammonium carbonate-bicarbonate leach solution. Ammonium systems had been used in the early ISL mines until it was known that ammonium could oxidize to nitrates. The EPA had already established drinking water standards for nitrates, thereby raising the question of ammonium restoration.

We may never know or be able to prove the extent of groundwater contamination from the early uranium exploration in Weld County. One study was done on the groundwater contamination from the Grover site. Restoration for the Grover ISL test mine was completed in February 1979. Follow up testing was done four months after restoration, in June 1979. Those findings were published in a thesis by Kenneth Wade ( Wade found groundwater tests in the Grover ISL wells showed a definite increase in alpha and beta activity as well as higher levels of radionuclide, molybdenum, ammonia, nitrate, and selenium in the groundwater after restoration. These findings concur with later studies from other sites:

Even where large quantities of water are available to flush parts of the aquifer, chemical processes that took place during ISL may have caused clays, once a protective layer for the aquifer, to have soaked up some of the metals and radionuclide and held them during the flushing process, only to release the metals into the aquifer months or years after restoration is completed. “Despite nearly 25 years of commercial ISL uranium mines in the United States (all using alkaline leaching solutions), regulators are yet to review or approve a report on the full scale restoration of groundwater at these sites” (See Page vii of An Environmental Critique of In Situ Leach Mining: The Case Against Uranium Solution Mining).

Grover’s ISL well fields were drilled in a five spot well pattern. During the ISL operations no excursions were detected. However, Wade points out excursions would not have been detected since even the closest monitor well down gradient to the ISL field would not intercept the natural groundwater flow from the field for 2.7 to 7.5 years! The National Research Council recognized that “Once in the aquifer, a contaminant will move with the groundwater at a rate varying between a fraction of an inch to a few feet per day” and that “the tangible effects of groundwater contamination usually come to light long after the incident causing the contamination has occurred. This long lag time is a major problem.” (

“Natural discharges of an aquifer, such as at springs and seeps, can return a contaminant to the surface. Because of the slow rates of groundwater movement and natural flushing of aquifers, when areas are contaminated, they commonly remain so for decades or longer.” (

Semi-arid Colorado is familiar with water shortages. Farmers, ranchers, in situ leach mining operations, and growing cities wrestle over their rights and needs for water. “Water in the South Platte Basin is used seven times before it dries up or it reaches the state line. Somewhat similarly, if upstream water is removed from canals, the hydrological flow to distant farms becomes more difficult, encouraging remaining farmers to cash out. Once the farms are gone, so are jobs.” (

Farmers and ranchers are not the only ones feeling the pinch for clean water in the South Platte River Basin. The city of Sterling notified their citizens not to drink the water because it contained high levels of uranium and nitrates. The current estimated cost of a treatment systems is from $10.5 to $20 million. (

West of Sterling, the Merino Town Council is looking for ways to remove uranium from their water. It is not clear where the uranium came from that contaminates the cities’ waters, nor is it clear where the money will come from to remove the uranium from the drinking water supply. Regarding the high levels of uranium and nitrates, Sterling’s newspaper quoted one wastewater engineer as saying “It comes from geology. It comes from the mountains.” (

Colorado’s Department of Natural Resources may disagree:

Uranium concentrations in the ground water of the lower South Platte River basin alluvium tend to be higher than in the mountains indicating a secondary source of dissolved uranium. (Dennehy and others 1998). Possible sources include coal beds in the bedrock subcropping beneath the alluvium. In 1994, the uranium concentrations in alluvial ground water exceeded the proposed standard of 20 parts per billion (Dennehy and others, 1998) (Ground Water Atlas of Colorado).

Sterling and Merino provide examples of the difficulty in proving a source of groundwater contamination. The cost of clean up is often placed on the end user who needs the drinking water.

As surface waters become less available to meet growing demands, aquifers become more valuable. Unfortunately this groundwater which is already a “major source of water supply in the United States, is facing sever quantity and quality problems. Once contaminated, the options available for its use are both limited and costly.” (

The structures within an aquifer that are responsible for the slow movement of groundwater are the same reasons contamination cleanup within the aquifer is so difficult and expensive. “Restoration of contaminated aquifers can be extremely expensive. The cost of cleanup may be so great that society may simply have to designate certain aquifers as permanently contaminated and unsuitable for further use other than for waste disposal.” (

The proposed Centennial ISL uranium mine is located within the boundaries of three important and heavily used ground water sources for Colorado: the alluvial aquifer of the South Platte River Basin, Denver Basin’s Laramie-Fox Hills aquifer, and the Dakota-Cheyenne Aquifer which is the most extensive water-yielding unit in eastern Colorado. The Laramie-Fox Hills aquifer and the Dakota-Cheyenne aquifer are confined aquifers, being bounded above and below by relatively impermeable clays or soil which water will move through a very slow rates.

Deep well injection of hazardous waste water might contaminate any of these ground water sources. “Subsurface-water flow cannot be seen or measured with the certainty that surface flow can, and thus its occurrence is less precisely understood.” (Ground Water Atlas of Colorado)

There are no methods for predicting the paths or speeds with which injected wastes may migrate into groundwater or escape to the surface. It is not possible to detect small vertical fractures in subterranean formations that can channel injected chemicals through nonporous layers into groundwater. Little is known about the long-term chemical behavior of chemicals that have been injected down deep wells – potential reactions between hazardous waste and underground rocks, clay, sand, water, brines, oil, gas, etc., or the effects such reactions might have on migration and toxicity. Once hazardous materials leave the well bore and enter the porous layer into which they are injected, it is not possible to track their movement. Their whereabouts become known only when they are found as groundwater contaminants. (

Gravity will force contaminated ground water to seek a path downward and laterally through naturally occurring fractures and porous geological layers or drill holes, until it discharges back to the land’s surface as a spring; as seepage into a stream, lake, or ocean; or into manmade structures such as a well. “Recharge of confined aquifers is through subsurface flow from adjacent unconfined zones and slow leakage from and through adjacent confining layers. For the most part, the Denver, Arapahoe, and Laramie-Fox Hills aquifers of the Denver Basin are examples of confined aquifers, where they are overlain by impermeable layers.” (Ground Water Atlas of Colorado). Manmade pressure in an aquifer, either from pumping water in or pumping water out, further complicates the flow of groundwater.

Where the Denver Basin bedrock aquifers subcrop beneath the alluvium, they are in hydraulic connection and discharge into the alluvial aquifers of the lower South Platte River basin. In the upland areas of the Denver Basin, and near the foothills where the streams enter the Denver Basin, the alluvial aquifers recharge the bedrock aquifers. As groundwater withdrawls in the Denver Basin aquifers increase, declining water levels will reverse this relationship, with alluvial ground water recharging the bedrock aquifers even in the lowland areas. (Ground Water Atlas of Colorado).

That a deep disposal well might be used for disposal of uranium mining land and well field waste may be of concern to current and future water users in Weld County, as well as other counties along the South Platte River. The proposed Centennial ISL uranium project is within the boundries of the Laramie Fox-Hills aquifer. The aquifer’s contours “indicate that ground water discharges into the alluvium of the South Platte River and its tributaries northeast of Brighton” (Ground Water Atlas of Colorado).

Map courtesy of Colorado’s Department of Natural Resource’s Ground Water Atlas of Colorado

The 14th Water Quality Conference on Groundwater Quality and Treatment was held in Illinois in 1972 where L.A. Wood presented a paper titled Groundwater Degradation-Causes and Cures. Wood’s writing regarding groundwater remains true:

Its availability at the point of need makes groundwater an extremely valuable natural resource. However, all groundwater is no longer pure and uncontaminated because the activities of man have degraded some of it. The time required to flush pollution from an aquifer will range from a comparatively short period to periods measured in geologic time. Monitoring waste movement in aquifers will not prevent pollution, but will show where it is or is not. The most satisfactory cure for groundwater pollution is prevention.


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