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Main waste rock dump at the Tintic Standard Mine.

Main waste rock dump at the Tintic Standard Mine.

In this post, we will report results and draw conclusions for our study of soil contamination in the Tintic Mining District. This study was supported by a grant from the American Chemical Society.

Students from Walden School of Liberal Arts brought back 42 samples of soils from the area in and around Eureka, Utah. Our purpose was to test for heavy metal contamination, especially lead. Previous tests done by the Utah Department of Health and the EPA showed lead contamination to be widespread throughout the town, due to the presence of historic concentration plants in the town and the use of mine waste rock as fill in many lots. Since there are mine dumps on the hillsides south of town, rain runoff also brought lead contamination into the residential areas.

Western side of the Swansea Consolidated mine dump near SIlver City.

Western side of the Swansea Consolidated mine dump near SIlver City.

These tests led the EPA to declare the town a Superfund project and spend $26 million to replace soils in some areas of town (but not all). They also placed limestone riprap over the mine dumps to prevent further runoff. The process took ten years and completely changed the look of the town, damaging or destroying several historic landmarks along the way, such as the headframes for the Eureka Hill and Gemini mines. Two landmarks, the Bullion Beck headframe and the Shea building, were restored. The rest have been left in ruins.

Middle section of the Swansea Consolidated mine dump near Silver City.

Middle section of the Swansea Consolidated mine dump near Silver City.

All of the tests we conducted were put into numerical form and entered into a spreadsheet so that we could compare the results. We used an ALTA II reflectance spectrometer to measure reflected light at eleven wavelengths, including four infrared wavelengths. We also tested the pH of the samples using several methods, including universal test strips, a garden soil test kit, and a pH meter. We tested for lead using a sodium rhodizonate solution, which changes from orange-red to pink in the presence of lead in neutral soils and to green or blue in the presence of lead in acidic soils. Please see our previous post for details on these tests. Since the rhodizonate test was qualitative, we assigned numbers depending on the color of the final solution so that some comparison could be made.

For the samples, we selected ten areas inside the town of Eureka, including some where the soil has been replaced and others where the soil is original. We tried to pick areas that were representative of the town as a whole. At each site, we sampled the surface soil and soil about six inches below the surface. We also sampled 12 sites outside of town, including areas away from town as controls and areas on or near exposed mine dumps, such as those from the Tintic Standard, Swansea Consolidated, and Tesora mines. We also took samples from gullies or washes downstream from mining areas and dumps, and from an exposed ore body (which has not been mined or processed) at a road cut along U.S. Highway 6.

Test Results:

Chart 1: Comparing Different pH Tests of Soil Samples. The readings taken with our portable pH meter provide the most consistent results (and can be done easiest in the field).

Chart 1: Comparing Different pH Tests of Soil Samples. The readings taken with our portable pH meter provide the most consistent results (and can be done easiest in the field).

As you can see from Chart 1 shown here, of the different methods we used to determine the soil pH, the pH meter was the most sensitive and consistently accurate. It was also easiest to use. It showed that most of the samples, were slightly acidic (between 6 and 7), but the samples taken from mine dumps and the areas immediately downstream were extremely acidic; in fact, some samples had a pH too low for our meter to read, which had a low limit of 2.5. Although not shown on this chart, the samples taken inside Eureka on our fourth collection trip all showed pHs near neutral (6 – 7).

Our lead test showed no discernable lead inside Eureka, even in soils that had not been replaced by the EPA. This is probably because our test is not sensitive enough for low lead levels. It becomes hard to distinguish the original color of the rhodizonate from the natural color of the soil unless there is enough lead present to create an obvious color change. In Chart 2, low levels of lead correspond very well with neutral pH soils.

Chart 2: Comparing Soil pH with Lead Levels. The lower the pH (more acidic) the soil samples were, the more lead was present with a correlation coefficient of rho = -0.876.

Chart 2: Comparing Soil pH with Lead Levels. The lower the pH (more acidic) the soil samples were, the more lead was present with a correlation coefficient of rho = -0.876.

The most interesting result of our study was to compare pH with lead levels. Chart 2 shows that the highest lead levels were found on or immediately downstream from mine dumps, which correlated very well with low pH levels with a correlation coefficient of rho = -0.876. Mine dump soils had high lead content and were highly acidic. Of course, this doesn’t imply causality: the high acid doesn’t cause lead, and the high lead probably doesn’t cause the acidity, but if one is present, so is the other.

Chart 3: Comparing Soils at Mine Dumps with Healthy Soil Using the ALTA II Reflectance Spectrometer. Healthier  soils were darker and richer in humus, whereas mine dump soils were pale and yellowish.

Chart 3: Comparing Soils at Mine Dumps with Healthy Soil Using the ALTA II Reflectance Spectrometer. Healthier
soils were darker and richer in humus, whereas mine dump soils were pale and yellowish.

In Chart 3, the reflectance spectrometer tests were inconclusive as far as detecting a signature for lead. We compared the results shown with samples of pure lead, pure galena (lead sulfide), and silver-lead ore. There were no obvious wavelengths that gave a definitive fingerprint for only lead.

The one useful result of the spectrometer tests was to confirm the overall health of the soil samples; those with lower percent reflectance overall were darker, richer, more healthy soils with more plant life growing. The lighter soils had less plant life and higher overall reflectances. The soils at mine dumps were yellowish to light purplish due to the presence of sulfur compounds, and these also had no plant life, lower pH, and higher lead.

Chart 4: Comparing the Levels of Nitrogen, Phosphorus, and Potassium in Soil Samples. The nitrogen and phosphorus tests gave no predictable results, whereas the potassium test showed higher levels of potassium in mine dump soils with high lead content (rho = .687).

Chart 4: Comparing the Levels of Nitrogen, Phosphorus, and Potassium in Soil Samples. The nitrogen and phosphorus tests gave no predictable results, whereas the potassium test showed higher levels of potassium in mine dump soils with high lead content (rho = .687).

Chart 4 shows the tests we conducted on soil nutrients. The nitrogen and phosphorus tests were inconclusive, and are probably due to the poor quality of the garden test kit we used. The potash (potassium) test did show higher potassium in the mine dump soils where lead levels were also highest, although the correlation was only moderate (rho = 0.687).

Conclusions:

A visual inspection of the mine dumps outside of Eureka, Utah in the Tintic Mining District shows that the waste rock and soils are highly contaminated. No plants grow on the dumps or in the gullies immediately below them. They are stained a bright yellowish-orange, and soils in the nearby gullies have layers of red, yellow, and even green. Overall, they are lighter and less rich than nearby soils with plant life. Our tests show that these mine dump soils are acidic and have high levels of lead contamination.

Similar mine dumps were located at the west end of town (around the Gemini and Bullion Beck headframes) and south of town (Chief Consolidated and Eagle and Bluebell mines). If the same pattern of contamination occurred there as what we found in the Swansea, Tesora, and Tintic Standard dumps, then it is likely that the soils downstream in the residential areas of town were also contaminated by lead and sulfur compounds. We did not find evidence of this in our tests of original soils inside town, but our test was not sensitive enough to find the lowest levels of lead. Soil pH throughout the town was slightly acidic, which may indicate sulfur or even lead content. We were not able to get the data from the original EPA tests.

Soil discoloration in the wash west of the main Swansea mine dump at Silver City.

Soil discoloration in the wash west of the main Swansea mine dump at Silver City.

Both pH and potassium content appear to be well correlated with lead content, with pH having a particularly high negative correlation (-0.876). Perhaps pH can be used as a marker, since it is easily measured. Where lead is suspected, a pH reading showing high acidity would indicate a strong possibility of lead. It would be interesting to see if the two measurements decouple as one travels further downstream from the mine dumps along washes and gullies. Do the lead and the acid travel the same distances?

Soil layers showing different types of contamination, in the middle wash downstream from the Swansea mine dump.

Soil layers showing different types of contamination, in the middle wash downstream from the Swansea mine dump.

Much remains to be tested. We have some additional grant funds that we will use to send four samples to an outside lab for detailed element analysis. I also hope to take all our samples to a local university and use an X-ray Fluorescence Spectrometer or Raman Spectrometer to get an accurate and precise readout of the lead levels and other heavy metal content. We need to determine the amount of sulfur compounds in the soils, and how that correlates with pH. We also need to pass our samples through a soil sieve and measure the relative sizes of particles and the amount of humus in each. We should test the mine dump soils to see if plants will grow in them compared to the other samples. Finally, we need to return to the site and collect more samples of other mine dumps, as well as the soils around and downstream from the dumps we’ve already tested. We need to determine how far the lead contamination and acidity travel down the washes and gullies and the extent to which the slope of the land affects this.

As with any field research study, it’s hard to keep all the variables constant. We’ve been careful and consistent with our tests, recording each location and using controlled testing conditions in the lab. But there are factors we can’t control. It could be that the low plant life on the dumps is simply because this is a desert, and plant life takes time to get established after soils are disturbed. The dumps were all dug up and the best materials were transferred to a leaching pile nearby in the 1980s. 30 years is not enough time for climax vegetation of sagebrush and juniper trees, but is enough time for grasses and low brush to grow. In general, soils in the area are poor in nutrients except where higher levels of water (such as in washes or gullies) allow more plants to grow and decay into better humus.

Staining on the asphalt where water draining off of the Swansea mine dump runs over the road near Silver City.

Staining on the asphalt where water draining off of the Swansea mine dump runs over the road near Silver City.

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Replacing topsoil Eureka Utah

Replacing topsoil in Eureka, Utah

On my visit to the area around Eureka, Utah last Friday, June 4, I not only wanted to visit Mammoth and Silver City, but to also document the efforts by the Environmental Protection Agency to clean up the town. I had traveled through Eureka a few days before on Memorial Day and noticed that the lawn and soil around the LDS chapel in Eureka was being dug up to a depth of about 18 inches. On Friday, crews were in the process of bringing in new soil in dump trucks and spreading it over a layer of black plastic where the lawns used to be. Normally I wouldn’t have noticed it much – just chalked it up to them putting in a new sprinkler system or something similar. But I knew differently. This was the latest site in an ongoing process to replace the topsoil throughout the entire town, which is a huge undertaking. All the old mine sites throughout the district have left a legacy of environmental contamination and pose a danger to careless explorers who try to enter mine shafts or tunnels or ruins.

Ore dump at Dividend

Ore dump at Dividend, Utah

When silver ore was discovered in the East Tintic Mountains by George Rush in 1869, it ignited a stampede of mining claims that spread throughout these mountains. New deposits were soon located and claimed, and the ore was assayed to be rich in silver, gold, lead, zinc, copper, and other minerals, usually in the form of metal sulfides. The most level sites near the mines quickly grew into the towns of Eureka, Mammoth, Silver City, Diamond, Knightsville, Dividend, etc. These towns were usually as close to the mines as possible so the miners didn’t have far to walk, so that miner’s houses and the mine buildings, hoists, smelters, railroad depots, and city businesses all competed for space in the narrow canyons. Tailings dumps of discarded minerals and slag from the smelters covered the hillsides around and above the town. Dust from these piles was blown by the frequent winds (this is western Utah, after all) and blanketed the whole town. Nobody thought much of it at the time. It was all just part of life in a mining town. But the entire topsoil was contaminated with lead and other metals down to about two feet under the surface.

Limestone rip-rap in Eureka

Limestone rip-rap covering a slope in Eureka, Utah

Downtown Eureka with limestone rocks

Clean-up operations near downtown Eureka, Utah

Today, the EPA has identified the area around Eureka as a SuperFund site, spending millions of federal dollars to clean up the contamination.  One by one, the yards of the residents and businesses are being dug up and the soil replaced, brought in from a staging area east of town. To prevent the tailings piles from blowing more toxic dust around the town, broken limestone rocks called rip-rap are being hauled in from a nearby quarry and are carefully placed to cover over the tailings piles to prevent further erosion by wind and water.

Mine dump in Tintic Mts.

Mine dump in East Tintic Mtns.

The work is progressing throughout Eureka, but the entire mining district has the same problem. Recent exploratory work has dug up the tailings piles in Silver City again, leaving the yellowish sulfides once again exposed to erosion. Many of the mine sites in the hills are owned by small-time private owners who keep the mines open on an occasional basis. They don’t have the resources to prevent the erosion of their tailings piles, and much of the East Tintic Mountains is contaminated just as Eureka itself is.

Old mine shaft

Abandoned mine shaft at Dividend, Utah

Another problem in the area is the many abandoned mine tunnels and shafts. Mines today are required to provide reclamation funds before the mine can even open, but it wasn’t an issue in the 1800s and early 1900s when most of these mines were active. The owners took the ore from the hills, then left all the scars, holes, pits, slag, tailings, and buildings behind when the ore ran out and their companies closed. Now these ruins are a hazard to casual explorers; every year or two someone dies falling down an abandoned mine shaft in Utah. The state has begun a program to close off these mines; to place grates or metal doors in the tunnels and shafts or to blast the entrances closed. Over 8000 mine sites have been closed off throughout the state through this program, but many, many more remain to be done.

Knight Smelter at Silver City

Ruins of the Knight Smelter at Silver City, Utah

Smelting or concentrating the ore brought its own environmental problems. Jesse Knight, the silver magnate that started Knightsville just southeast of Eureka, also built a smelter at Silver City in the early 1900s that operated for about eight years. The foundations of this smelter still remain, as do residual chemicals used to concentrate the ore, including mercury. When I visited the site on Friday, I found a man and his two young girls exploring the site. I suggested that he wash off his girls’ hands and shoes carefully once they were done because the whole site is contaminated with mercury (June McNulty, who runs the Tintic Mining Museum in Eureka, told me that he used to play with pools of liquid mercury metal that would seep into pockets around the smelter).

Knight Smelter

Remains of the Knight Smelter at Silver City, Utah

Right to the south of the old smelter lies a large heap of grayish tailings, now slowing growing a crown of weeds and grass. All the tailings left from the Knight mill were scooped up in the 1980s and placed on a pad with drainage pipes running through the pile, then a solution of cyanide was pumped and sprayed over the pile, leaching its way down through the tailings and chelating with the remaining gold and silver. The ore from these mines has been worked and reworked to get every last fraction of value out of it. But now the pile has been left just like all the other piles around, but with the addition of cyanide. I don’t know if steps have been taken to reclaim the pile, but I wouldn’t want to walk around on it.

Leaching pile at Silver City

Cyanide leaching pile at Silver City, Utah

The efforts to clean up these environmental messes is necessary, but it does come at a cost beyond just money. To clean up the town and make it safe to live in, its essential history and character has been changed.  The heavy equipment moving in limestone and soil has shaken apart a number of fragile historical structures, including buildings, homes, and headframes. Where there were colorful tailings piles slowly returning to nature, there are now carefully constructed fresh piles of gray limestone rocks, an ideal hideout and breeding ground for rattlesnakes (no joke here – I ran over one in my minivan as I was driving up the road to Mammoth). Eureka doesn’t look the same as it did ten years ago.

One can argue that Eureka must be dynamic and capable of changing. It’s not a museum but a living town, and change is part of life. But the historian in me hates to see history destroyed in the process. That is one of the main reasons I’ve started the Elements Unearthed Project and have traveled to Eureka several times in the last few years with my cameras and equipment; as the EPA clean up progresses, the town is changing and I want to preserve what can be preserved of the history before it’s gone forever.

Tailings piles at Silver City

Erosion of tailings piles at Silver City, Utah

The beryllium video second half is progressing well. I’ve decided to do the three episodes on the TIntic Mining Districts next instead of blown glass because It’s fresh on my mind and I now have all the footage and photos I’ll need. My goal is to get the beryllium video done and uploaded by the end of this week, then the Tintic videos by mid-July. Then I’ll start hitting the streets looking for financial sponsorship to continue this project.

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