The Five Mines - Phoenix Park Mill
The Phoenix Park Mill, constructed in the late 1960’s, is believed to have been built as a washing plant for ore that came from the Solomon Mine. Similar to a sand and gravel operation, the washing plant was designed to remove the abundant clay associated with the ore. Gold, silver, zinc, lead, and cadmium are some of the metals that were milled the Phoenix Park Mill. In 1971, milling operations ceased on the site, after the Solomon was abandoned, with about five acres of tailings and waste rock material remaining on the property.
In 2003, the U.S. Forest Service, in partnership with the Willow Creek Reclamation Committee, the Colorado Non-point Source Program, and the Colorado Division of Mining Reclamation and Safety, reclaimed about 2.5 acres at this site. Approximately 3,200 cubic yards of tailings were consolidated and covered, and native soil embankments were graded into the ponds to create positive drainage from the site. A combination berm and ditch was constructed to direct drainage away from the depression and down the road. The disturbed areas were seeded, fertilized, and mulched in 2004. Several large boulders were placed at the southern boundary of the property to prevent vehicular access and improve revegetation success. In 2005, the site was treated with mushroom compost to provide additional organic material necessary for plant growth on the site, since the first seeding in 2004 did not take successfully. The final treatment in 2005 was very successful.
Partners: WCRC, CDRMS, USFS, CDPHE (NPS)
Total Cost: $36,910.00
The Phoenix Park Mill Tailings site consists of two separate ponds containing mill tailings. Below the lower tailings pond is a decant structure consisting of a concrete bunker and flow valve. The preferred reclamation method for the Phoenix Park Mill Tailings is to cap in-place.
Prior to earthwork, the pipe leading from the lower tailings pond and the decant bunker must be sealed by filling the upper end with one bag of sand and cement mix or refusal. The concrete mixture must have a high slump (6-8”). The concrete bunker must be removed and the concrete placed inside the lower tailings pond. Following removal of the bunker, the decant pipe must have a cap welded onto the end. The cap must be welded continuously around the pipe. Once the cap is welded, the bunker area must be graded to conform to the surrounding topography.
The mill tailings in the upper pond have been measured to be approximately 4-5 feet in depth. These tailings will be graded into the lower pond after removing and stockpiling the embankment between the ponds. The top one foot of the soil material underlying the mill tailings will also be removed and placed on top of the consolidated mill tailings. Approximately 3,200 cubic yards of mill tailings and underlying soil must be moved.
Following consolidation of the mill tailings, the embankments will be graded into the ponds. The final graded surface must have positive drainage from the site. The material must also be graded to the top of the existing cuts on the western side of the ponds. Trees on the east side of the ponds must not be disturbed. The soil in the east embankment must be removed using an excavator or other piece of equipment that will not disturb the trees adjacent to the embankment. There are areas in the embankment that currently do not support vegetation. In general, these areas are lighter in color and contain more rock. The light colored, rocky materials must be placed over the consolidated mill tailings and/or at least one foot below the final fill surface. The remaining soil material must then be placed over the light colored material. The estimated volume of material in the embankments that must be moved is 8,200 cubic yards.
Following regrading, a berm must be constructed along the road adjacent to the ponds to direct drainage away from the regraded surface. The berm must be a minimum of two feet in height with 2h:1v side slopes. As an alternative, a combination berm and ditch can be constructed. The ditch must be a minimum of one foot in depth and the berm must be one foot in height. The side slopes of the ditch and berm must be a minimum of 2h:1v.
Following all earthwork, the entire disturbed area must be revegetated according to