INSPEC45635

• Permit No: M1976020
• IBM Index Class Name: Inspection
• Doc Name: MINERALS PROGRAM INSPECTION REPORT
• Inspection Date: 2/1/1995
• Media Type: D
• Archive: No

• (Page 2) •
MINE ID ~ OR PROSPECTING ID ~ N-76-020
INSPECTION DATE 2 1 95 INSPECTOR'S INITIALS TAS. SS
1. Tom Schreiner and Steve Shuey of the Division conducted an inspection or the Thomas Pit.
The site ie permitted for 29.8 acres of disturbance with a financial warranty of $9250 in the
form of a corporate surety. The poet-mining land uses will be irrigated pastureland and
natural river channel. The Thomas Pit is situated in the floodplain of the Animas River
approximately 2 miles north of Hermosa, Colorado. The permitted area includes an overflow
channel of the Animas River created by historic mining and an upper bench area used for
processing and stockpiling of product. The upper bench area will be reclaimed to irrigated
pastureland. The river channel will be returned to its original condition, river wash.
2. The area was once the site of a gold dredging operation which left a large hole
approximately 200 feet wide by 900 feet long and a channel into it from the river.
Separating the dredge hole and the channel from the river is a dike approximately 1,400 feet
long and 20 feet wide. The channel and hole are on the west aide of the river's main stream
and during heavy runoff are flooded by water from the river. This runoff d.epoeite sand and
gravel in the hole and channel.
3. The mining plan consists of removal of sand and gravel from the channel and/or dredge
hole with dozers, front-end loaders, and other equipment ae necessary during the low flow
period. When dewatering is required for excavation the water is pls~ced in a ditch
approximately 1,200 feet long and drains into a settling pond. Discharges from the pond
occur under the terms of an NPDES permit issued to the operator by the Colorado Department
of Health.
4. The mining plan specifies that the maximum depth of excavation will be 30 feet even
though the sand and gravel deposit ie estimated to be 50 feet thick. The operator reported
they have been excavating 10-15 feet of material over a 50 foot reach of the channel during
the past few seasons. In moat years, several peak flows are required to fill in this depth
of excavation. In 1994, however, the excavation was filled completely. A concern arises,
however, in that the operator has not defined in the permit application the relationship
between the maximum depth of excavation in the dredge channel and the low flow elevation of
the west channel of the Animas River. Across section has been provided, however, specific
elevations are not included. The Division requests that this relationship be clarified and
requests that a specific elevation be set in order to more adequately define the maximum
depth of excavation. Such a limit may aid the operator in minimizing potential impncte to
the hydrologic balance ae well ae minimizing the potential for offeite damage. Ae an
example, limiting the depth of excavation to the top elevation of the low flow channel in the
west channel of the Animas River should minimize the potential for hydro:Logic or offeite
impacts and should improve the feasibility of reclamation. We note this concern ae a problem
that should be addressed within 60 days. Specific corrective actions are listed on page 3.
5. The operator ie in the process of preparing an application for a 404 permit to be
submitted to the U.S. Army Corps of Engineers. Part of the application krill include the
operators plane for improvements in the dike at the downstream end of the dredge channel.
The Division requests that the operator incorporate the provisions of the 404 permit
following approval from the COE into the existing mining and reclamation permit. The
Division will advise the operator prior to submittal whether the provisions of the 404 permit
will require a technical revision or an amendment to the permit.
6. Review of the permit file indicates that there are no provisions for baseline monitoring
or .annual surveys of the overflow channel in the area to be mined. Berhan Keffelew of the
Division previously requested channel survey data following an inspection in July, 1991. Our
records indicate that the requested data has not yet been supplied. In order to resolve this
concern we request that the operator submit a baseline survey of the overflow channel prior
to future mining and commit to submitting an annual cross-section of the overflow channel
following mining each year in order to verify compliance with the mining plain. We note this