PERMFILE133700

• Permit No: M1991146
• IBM Index Class Name: Permit File
• Section_Exhibit Name: EXHIBIT A
• Media Type: D
• Archive: No

Corps of Engineers Revisions: (2/12/92)
4a. ACTIVITY
It is proposed to excavate gravel from the Uncompahgre
River channel system, outside the active channel, with a
rubber-tired loader.
Phase I excavation will be approximately 100 ft wide by
800 ft long, on the west side of the river, between an e>isting
berm and a Ponderosa Tree Boundary as shown on the attached
Flan View. The attached Longitudinal Section of the river
shows the maximum depth of mining to be 10 ft. The west slope
of this area is along the tree boundary and will be maintained
at 3: 1. This slope will be rip-rapped on the south end where
the diverted river of F'hase Il will be turned to the north, and
along the north end where the diverted river will return to the
existing channel. Rip-rap will have a median size of 2 ft and
meet the requirements of the State ^f Colorado, Specifications
for Road and bridge Construction, as per Buckhorn Geotech
recommendations. (See attached Buckhorn Geotech response to
MLRD adequacy letter dated 1/13/92).
Phase II excavation will be approximately 150 ft wide by
1000 ft long by 10 ft deep, an the-east side of the property,
in the area of the present active channel. It is proposed to
cut the berm near the south boundary of the permit area,
construct a temporary diversion similar to the existing berm,
and allow the active channel to relocate within the area
between the berm and the west slope of Phase I. This channel
will rejoin the present active channel near the northwest
corner of the property. At the conclusion of mining in the
Phase II area, the diversion will be removed and the river
returned to the historic main channel where it now exists.
Based on a meeting at the project location with the Cvrps
of Engineers, Mined Land Reclamation and Duray County, the
fallowing is to answer questions and respond to suggestions
regarding water quality, siltation and potential off site
impacts.
WATER QUALITY: The proposed gravel excavation will be
conducted away from the active channel and above the
projected water table. The attached Buckhorn Geotech
information shows a cross section drawn through .an
adjoining domestic well on the Webb property, recently
constructed Monitoring Well No. 3 and the Uncompahgre
River. The projected water table is shown at the time of
the Webb water well construction on August 9, 1974, and
on February 1, 1992. Since the permeability of the
alluvium is very high and the movement of the water from
the streambed is primarily downward, it is very unlikely
that water will be encountered in the excavation areas.
-three monitoring wells have been constructed to a depth 5
ft below the proposed mining elevation as shown on the
Plan View and Cross Sections. Water table elevations
will be routinely measured in the monitoring wells and in
the Webb domestic well so that mining activities do not
Page 2 (Application)