PERMFILE105229

• Permit No: M1989029
• IBM Index Class Name: Permit File
• Doc Name: APPLICATION FOR A MINING SPECIAL PERMIT
• Media Type: D
• Archive: No

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' E%HIBIT G
Nl~TER INFORMATION
' Ttie proposed mining operation at Distel Farm is expected to have
ati impact on the surface and groundwater system in the area.
Ttiis impact has been studied and mitigation measures are proposed
' that will not cause material damage to any property owners or
wzeter rights owners.
Tt~e Distel Farm is located below the City of Longmont along St.
' Vrain Creek. The proposed pit will be located off-channel from
ttie creek. The mining area will be de-watered and operated as a
dry mine. A pump will be installed in the pit and all
' groundwater and surface drainage will be discharged to a wasteway
connected to St. Vrain Creek.

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Surface Drainage
Ttee area surrounding the proposed mine is predominately
a<tricultural in nature. Property along St. Vrain Creek is a
mj.xture of woodlands, wetlands, oxbows and active farmland. St.
Vrain Creek drains approximately 430 square miles of land
uF>stream. The width of the stream channel ranges from 50 to 100
feet.
A Flood Insurance Study was published for the City of Longmont in
Se:ptember, 1987 which included St.Vrain Creek. Table G-1
sLtmmarizes peak flood flows for varying return periods.
TABLE G-1
St. Vrain Creek Peak Flood Flows
Return Period
Tern Year
Fifty Year
Oc~e Hundred Year
Five Hundred Year
Discharge Icfs)
5,350
12,120
16,520
40,080
A portion of the property lies within the 100 hundred year
' fl.oodplain as shown on Exhibit C. It should be noted the
proposed location of the plant site lies ou tside the floodplain.
' Tteis will eliminate
erosion that would stockpile erosion during
occur from localized surf a major flood. Any
ace drainage would be
contained in the po nds created by mining and would not enter the
creek.
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' G-1