Leviathan Mine, SE of Lake Tahoe, CA - Bench Testing / Site Evaluation

Leviathan Mine was a copper‑copper sulfate mine that was in production intermittently from 1860 till 1962. The site is approximately 20 miles south of Lake Tahoe at an elevation of 7000 feet. The site has extensive underground workings as well as multiple open pit sites. Water from this site drains into Leviathan Creek and eventually into the Carson River in western Nevada.


In order to keep the AMD out of the Carson River, four large ponds were constructed to catch the total AMD discharge from the site. The capacity of these ponds is in excess of 6 million gallons. It was also believed that there would be sufficient evaporation during the summer to accommodate the following year discharge. This turned out to be wishful thinking. In reality all they created was very concentrated AMD that is almost impossible to treat.


Because of evaporation the amount of iron, aluminum, copper, arsenic and sulfate levels are very high as compared to the other heavy metals. In pond # 4 some of these levels exceed those from Iron Mountain Mine.


In early 1999 a four gallon sample of Leviathan Mine pond #3 AMD was treated with the standard HPT demetalizing process. This sample had been collected late in 1998 and had been greatly concentrated by evaporation. This sample required significantly more base than expected and it took several chemical hydroxide additions to keep the pH above a 8.5.


The treated AMD was filtered and .825 pounds of 80% moisture metal hydroxide cake was recovered. Upon doing the weight of the cake, it was reduced to .155 pounds or .05 pounds of dry sludge per gallon or less than 2 tons of sludge per million gallons. In addition, 3.5 gallons of the 4.25 gallon sample were treated with the membrane device.


And, 2.65 gallons passed through the unit as dischargeable water and .85 gallons of sulfate concentrate bypassed by the unit as a side stream. Tests of this side stream gave a sulfate concentration of 79,700 parts per million. This .85 gallon of concentrate was treated and converted to 2.2 pounds of an agricultural sulfate product. This would equate to 2.58 pounds of sulfate material produced for every gallon of concentrate generated.

Untreated AMD Leviathan Mine Pond #3

After Two‑Stage Treatment of Leviathan Mine AMD Pond #3

This two‑stage treated water now exceeds drinking water standards for these metals and sulfates.