GENERAL35957

• Permit No: M1999002
• IBM Index Class Name: General Documents
• Doc Date: 7/22/1999
• Doc Name: FINAL ENVIRONMENTAL IMPACT STATEMENT VOLUME 2 APPENDIX H
• Media Type: D
• Archive: No

This sequence of operations will cycle across the well field as mining panels are developed and
retired. Retirement and reclamation of mining panels is discussed in the Reclamation Section
5.0 of this document. During aII phases of project development and operation, appropriate
erosion and sediment control measures will be conswcted and maintained.
The principal BMPs that will be used during well field operation include silt fencing, channels
and diversions, level spreaders, check dams, sediment traps, drop swctures, water bazs
establishment of interim vegetation, vegetative filters, surface roughening, geotextile fabrics
and mulching. These methods and swctures may be used individually or in combination to
effectively control erosion and sedimentation.
Silt fencing will be placed as a temporary perimeter erosion and sedimentation control while
solution wells are developed and placed into operation. Silt fencing will be used to treat water
from disturbance associated with the conjwction of well pads, access roads, solution collector
pipes and pumping stations. When concentrated drainages are encountered, diversions will be
used to route runoff azound the disturbed area. When it is not feasible to divert flows, runoff
will be routed through disturbed areas via properly designed and conswcted channels, Check
dams with pervious outlets may be used to release water from disturbed area diversions,
channels and silt fences. Channel linings will be provided as needed based upon flow
velocities to ensure diversions and channels are erosionally stable and to prevent excessive
sedimentation.
Level spreaders may be placed at the outlets of minor diversions, channels and road ditches to
disperse concentrated flows and provide irrigation for downslope vegetation. Level spreaders
will work best for swctures that are expected to carry 10 cfs or less. In moderately sized
channels it may be necessary to use sediment traps and drop swctures to control erosion and
sedimentation. Moderately sized channels typically carry 10 to 250 cfs. In lazger channels
where peak flows are expected to exceed 250 cfs, check dams may be placed to control channel
gradients and cross sections, and prevent excessive erosion. These check dams may be
conswcted using various materials depending upon the anticipated operational life of the
swcture and the estimated peak flow.
Water bars may be used to collect and divert storm water runoff across and away from well
pads, access roads, and solution collector pipelines during the operational life of a minting
panel. Their successful use depends upon adequate constnmrction at frequent intervals
determined by slope (Table 4).
After development disturbance is completed, silt fencing will be systematically replaced with
more permanent, lower maintenance erosion and sediment control methods and swctures. Cut
and fill slopes may have their surfaces roughened using plowing, ripping, land imprinting or
contour furrowing operations. Roughening will provide erosion and sediment controls while
longer-term measures, such as the establishment of interim revegetation and vegetative filters,
are implemented. Interim vegetation may be established on disturbed areas outside of normal
traffic ways. Mulch and surface amendments may be applied to promote vegetation
establishment and growth. On disturbed slopes steeper than 2h:ly, geotextile fabrics may be
used in conjunction with the establishment of interim revegetation seed mixtures to control
erosion and sedimentation, while helping to promote vegetation growth and establishment.
Interseedings to establish or enhance vegetative filters at the bottoms of disturbed outslopes
may also be performed.
American Soda. L.L.P. ¢-~]
Soil Conservation. Erosion antl Sedimrnt
Control. Reclamation. and Revegeration Plan
October 28, 1998
Revised April 9. 1999