The ghosts of Valmont Butte

Ever since the city of Boulder purchased its Valmont Butte property, city taxpayers have been picking up the tab to pay for the environmental sins committed by more than a century’s worth of long-departed users at the site.

And that tab may be getting bigger as more ghosts from the property’s past continue to reveal themselves.

Valmont Butte has always been a magnet of sorts. It has always pulled humanity to its vista. Long before the first white settlers arrived in the area, Native Americans were climbing the gentle slopes of this unique rock outcrop east of Boulder to camp, hunt, enjoy the view and pursue a variety of spiritual practices. The Butte was important to several tribes in life as well as in death, as illustrated by the many archeological artifacts and suspected native graves that have been discovered at the location over the years. These are the original ghosts of Valmont Butte.

Later, early settlers formed the town of Valmont at the base of the rock formation along its northern side. For a while the bustling community boasted three saloons as well as a newspaper, and it rivaled Boulder as the population center of the county. Like those who came before them, when these early residents died, they often preferred to be buried above the valley floor on the high plateau on the southern side of Valmont Butte in what is today the Valmont Cemetery. More ghosts.

The very quality that has always made the butte popular, its improbable castle-like rock formation known as the Valmont Dike, which forms a natural spine of stone running to the east for several miles and creating the butte’s impressive juxtaposition to the surrounding plains, may well have been its curse as well. 

The butte’s sloping sides have made it an ideal location for hard rock milling operations since the 1890s, and its sheer rock face on the western side has been a quarry operation for even longer, most likely beginning in the 1870s. As a result of these industrial operations, Valmont Butte has become disfigured and, more importantly, badly contaminated with radioactive mine tailings tainted with heavy metals. While most of the miners and mill workers who contributed to the contaminated mess on the property have long since passed, the company ultimately responsible for much if not most of the contamination along the butte is still around. Honeywell inherited some level of legal responsibility for the toxic mess at the Butte when it purchased Allied Chemical Corporation, which ran a fluorspar mill on the site from the 1940s until the late 1970s.

Valmont Butte as depicted in 1891 illustration (photo courtesy of Carnegie Branch Library for Local History)

But not every ghost that now haunts the butte and its current owners, the citizens of Boulder, are dead. Some, such as the city personnel who made the bizarre decision to purchase 103 acres of prime butte contamination on behalf of the rest of us, have simply disappeared over time, leaving behind one mystery after another regarding the hidden dangers and financial landmines buried below the surface of the butte.

But of the many people who have had a significant effect on the Valmont Butte site and its contamination, perhaps none have impacted the Boulder landmark more than the men and women who have worked for the various local, state and federal agencies charged with evaluating, monitoring, remediating and otherwise protecting the public from the dangers that have existed on the butte for more than a century.

An examination of the public record regarding Valmont Butte reveals a wild collection of contradictory assumptions, reports, policies, recommendations, actions and opinions spanning the past 50 years. These contradictions and inaccurate assumptions may yet come back to haunt City of Boulder taxpayers beyond anything contemplated by those who have obligated them to help pay for the past sins of some of the site’s ghosts.

This article is the first in a series of stories concerning Valmont Butte, including the approximately 103-acre parcel currently owned by the City of Boulder as well as other surrounding properties. Telling the story will require multiple installments because it is impossible to describe the very important nuances of the contamination problem in, on and around the butte, as well as the possible solutions to the problem, without a fair amount of data downloading and the occasional splitting of hairs. For instance, examining topographic maps from the turn of the century through the 1950s to counter the modern assumptions of some regulatory agencies regarding the topography that underlies the contaminated tailing ponds on the property is not particularly exciting stuff unless you are a map maker, hydrologist or environmental consulting firm, but it is very important — potentially tens of millions of dollars important. And considering that it’s at least a possibility that the City of Boulder, thanks to certain federal laws and their interpretation, could end up picking up a sizable portion of the tab for remediation going forward, such detail matters.

For future reference, we suggest that you keep this first installment and use the maps, photos and timeline as a reference going forward (you can download the maps and images at the bottom of this story). Space will not permit running the same graphic elements with each new story. We will, however, be posting these and other source materials online if you wish to view more resources from our investigation.

103 acres of prime contamination

Contamination is like barbeque sauce. It has an almost supernatural ability to defy our best-laid plans for its ultimate destination. The simple act of transferring the red, sticky concoction from bottle to rib to mouth rarely goes down as intended. It’s far more likely that, along the way, the sauce will suddenly appear on our forehead, elbow, jeans and hair, with long-distance stains reaching odd locations such as our back pocket or a sock. Unfortunately, when contamination exhibits this same quality of migrating to unexpected places, it’s neither humorous nor easily remedied, and it can get expensive.

That’s what has happened at Valmont Butte. The following is an overview of just a few examples of the difficulty of tracking, let alone containing, historic sources of contamination on and around the site.

While the rock quarrying, top-soil removal and clay extraction in the area over the last century have forever changed the appearance of Valmont Butte, these processes did little to contaminate the lands and will therefore be overlooked for the most part in our reporting.

The 103-acre tract of land currently owned by the City of Boulder (outlined in yellow on aerial photo map seen above) has been known by a variety of names over the years: St. Joe’s Mill, Allied Pile, Allied Mill site, Valmont Mill and Hendricks Mill are the most common. For our reporting purposes, we will use the name Allied Mill for the most part.

As can be seen on the timeline here, a gold mill was sited on the property in 1935 by St. Joe’s. This mill went bankrupt after two years. In 1937, the mill was converted into a fluorspar gravity floatation mill by two partners from Boulder who eventually sold the mill to General Chemical Company. General Chemical was purchased by Allied Chemical Company in 1941. Allied ran the fluorspar flotation mill on the property for more than 30 years. The end product of the fluorspar mill was calcium fluoride, which was shipped to the west coast by rail. Unfortunately, what didn’t get shipped away were the concentrated leftover radioactive tailings tainted with heavy metals that are still the dominant feature of the property.

The following is a quick description of the milling process, which can be followed geographically on the aerial map above.

The mill was built on the southwest slope of Valmont Butte in order to take advantage of gravity. The massive amounts of water used for the mill’s flotation process (up to 200,000 gallons a day) were pumped into holding tanks at the top of the butte and subsequently fed by gravity down into the top portion of the mill. From there, the whole process flowed downhill from floor to floor through the structure, which saved enormous energy costs. The overall property also falls downhill to the east, which also made the disposal of wastewater and tailings a matter of gravity.

The ore used by the mill came from the Burlington Mine near Jamestown. The Burlington’s ore contained several radionuclides, including uranium, radium 226, radium 228, thallium and vanadium. As the ore was crushed fine and mixed with a solution of water and a non-petroleum oil, the oil would stick to the calcium fluoride and float it to the surface, where it could be stripped off from the rest of the tailings at the bottom of the flotation stream. The calcium fluoride was then dried and placed in a rail car to ship west.

The remaining, concentrated slurry of radioactive tailings, tainted by heavy metals such as lead, arsenic and copper, was then sent downhill to the primary tailings pond, which occupied approximately 14 acres. The primary tailings pond is situated along the south side of the Valmont Dike, with a man-made dam on the north and a natural plateau on the west that cuts across the property from the dike and then turns to the east, forming a barrier on both the western and southern sides. This natural topography, plus the man-made dike dam, created barriers on three sides of the natural trough that sloped gently from west to east, down to a wetland at the easternmost edge of the city’s property. In order to prevent the natural flow of the contaminated tailings and water to the east, a dam made of tailings 30 feet in height was built across the eastern end of the trough to form the final barrier.

This description of the primary tailings pond is an important one, as it speaks to the ability of the contamination in the primary pond to potentially migrate to other parts of the property and even offsite. There will be additional detailed reporting on this issue of the city property’s underlying topography and its impact on the site’s contamination and remediation in the coming weeks.

Because the concentrated radioactive tailings were well above normal background levels, to operate legally, the Allied Mill site had to become a licensed holding facility for radioactive waste. The license was issued by the state of Colorado. Because of the long half-life of the radionuclide in the soil, it was assumed that the site would always be a licensed facility no matter who owned the property. That’s to say that it was assumed that someone would always have to be responsible for monitoring and storing the radioactive material because it was never going to become safe to be around.

This licensing approach to the radioactive contamination held true for years as the property was sold several times after the Allied Mill closed. This licensing requirement suddenly changed, however, in 1999, just a few months before the city purchased the property. More details on this unusual occurrence later in the series.

Eventually, the primary tailings pond became filled with contaminated waste and starting to spill over the dam on its eastern end. So a secondary tailings pond was created to the east, beyond the 30-foot-high dam of the primary tailings pond. This second tailings pond area was said to be approximately three to four acres. However, aerial photos from the 1960s show the secondary pond to be poorly defined, with tailings clearly pouring out to the south of the secondary pond and covering more than the historically stated acreage.

So exactly how much contamination is on the city’s Valmont Butte property, and exactly where is it located? Good questions that both the city and the regulatory agencies would love to be able to answer, but it’s not that simple. Judging from the lead and radioactive soils map, it’s pretty much everywhere (see listing of the types contaminants and their effects if humans are exposed here).

As to the question of how much, the seller of the property to the city, Valmont Butte Corporation, estimated that the primary tailings pond contained approximately 40,000 cubic yards of contaminated soil, which is equivalent to between 40,000 and 60,000 tons. This is the figure Valmont Butte Corporation presented to the Colorado Department of Public Health and Environment (CDPHE) in 1999 as part of its request to have the radioactive license for the property permanently terminated. However, the EPA now estimates that the primary and secondary tailings ponds hold more than 400,000 tons of contaminated tailings, a major discrepancy from Valmont Butte Corporation’s estimate, and even the EPA’s figure may be too low.

Based on an examination of Boulder County Public Health (BCPH) and CDPHE records from the 1960s, it was reported that 97,000 gallons of water were being used each day at the mill, and that this flow was creating 50 to 70 tons of contaminated tailings waste each day. Considering these figures along with estimates that in the 1940s, during the war effort, the mill was processing more than 200 tons of ore per day, and that other documents examined show that even in its final days, the mill was still using in excess of 40,000 gallons of water per day seven days a week, it could be conservatively estimated that between 600,000 and 750,000 net tons of contaminated tailings were actually generated by the Allied Mill. This would be in addition to the tens of thousands of tons of tailings that would have been generated by various milling operations both before and after Allied ran its mill on the property. Either more tailings fit into the ponds than has been estimated, or a couple of hundred thousand tons of contaminated tailings may have disappeared. Again, there may be explanations for where these tailings went, and this issue will be further explored in more detail later in the series.

In addition, serious lead contamination is all along the northern slope of the property from the top of the dike down to Valmont Road, from the dike dam to the wetlands on the eastern property line (see map). Lead is also a problem south of the second tailings pond and in several other locations in and around the old mill buildings and the Valmont Cemetery. Radioactive soils are also scattered across the property outside the tailings pond areas and have been found just about anywhere the wind has blown them over time. And then there is the issue of the elusive contaminated groundwater on the property. We say “elusive” because as recently as last week City of Boulder officials were still claiming that there is no groundwater under the property. An odd claim, considering that BCPH has monitored a 90-footdeep well on the property for decades, and monitoring wells drilled on the property in 2005 have groundwater contamination levels reported by EPA and descriptions as to what depths the water was encountered. Even wells drilled into the primary tailings pond found water-saturated soils at approximately 26 feet below the surface. The groundwater issue is an extremely important part of the Valmont Butte story and will be covered extensively in this series.

This is just a partial description of some of the contamination that has been identified and located on the City’s Valmont Butte property. Other questions remain, to be sure.

For instance, letters in the state and county records reflect a mysterious two month window when permission was granted by regulatory agencies for the Valmont tailings ponds to receive 25 tons per week of contaminated slurry from a Rocky Flats mill operated by a company called Strategic Metals International. Two months later, following testing of the slurry, a letter withdrew permission for the 25-ton-per week deposits into the ponds due to very high lead and cadmium levels in the slurry. It is unclear from the records whether or not Strategic Metals ever actually placed its contaminated waste on the Valmont Butte property and, if they did, where exactly did they put it and how much was dumped? And this is hardly the only contamination mystery at the site.

There is also the now infamous case of the missing 150 truckloads of radium-contaminated soils moved to the Valmont Butte property in 1971 from the city’s low-income housing construction site at Third and Pearl streets in Boulder.

As you can see from the map above, the city believes that the resting spot for the radium contamination is in one place, while the EPA believes that it is in a completely different spot on the top of the plateau to the west. This is an important difference.

If the city is correct, then they believe that when they finish constructing their new dirt and rock cap over the primary tailings pond, a cap designed primarily to prevent prairie dogs from digging up radioactive, lead-poisoned soil that can become an airborne hazard, the radium would be covered and considered to have been moved into the pond — a pretty cheap solution. But city officials don’t seem to be really sure where the radium is buried.

If the EPA is correct regarding the location of the radium, then the process of safely excavating the radioactive contamination and moving it into the primary tailings pond before it’s capped would become a far more expensive adventure. The city has already had to commit $2.5 million taxpayer dollars to the remediation process, and has no desire to spend more. Something that likely should have been considered before buying the property, but that, too, will be explored later in the series.

Sadly, for both the EPA and the city, they are both at least half wrong when it comes to the mysterious burial site of the Third and Pearl radium. An important document was found during Boulder Weekly’s investigation that describes what actually happened when the radium-contaminated soil arrived at the Allied property. The document says there was so much contaminated radium coming into the site that the first 90-foot pit became full, and a second pit had to be dug to handle all the remaining radium-contaminated soil. In other words, there isn’t one unknown burial site full of radium on the property. There are two unknown burial sites full of radium on the property.

The barbeque sauce is spreading, and this is just the tip of the iceberg. It’s easy to see how the city’s Valmont Butte property made it onto the federal Superfund list and at one point was described by a state official as having barely missed being put on the EPA’s National Priority List, which is reserved for the 400 most important sites to get funding for a Superfund cleanup. And if that isn’t enough, in the coming weeks we will examine whether or not the Allied Mill on the city’s property may have contributed contamination to other properties, including another Superfund site on an adjacent property. Allied Mill contamination also wound up in the lakes around Xcel’s coal-fired plant at Valmont Station, potentially creating a pathway to drinking water supplies. There are significant issues surrounding the Valmont Cemetery as well as ongoing Native American concerns that must be addressed. All of this and more will be covered in our ongoing series, as well as an examination of the Boulder/ Honeywell voluntary clean-up plan.

Workers are scheduled to start moving dirt and contamination on the property next month.

Let’s hope there are no more ghosts hidden on the site.

But we wouldn’t bet on it.


Valmont Butte 1891 illustration

Valmont Butte large aerial map

Valmont Butte small aerial map

Valmont Butte contamination map


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