REV91389

• Permit No: C1981022
• IBM Index Class Name: Revision
• Doc Date: 7/12/1995
• Doc Name: SOMERSET MINING CO EAST YARD OND TR-026 PN C-81-022
• From: J E STOVER & ASSOCIATES
• To: DMG
• Type & Sequence: TR26
• Media Type: D
• Archive: No

::
. J. E. STOVER & ASSOCIATES
' 2768 COMPASS DRIVE, SUITE 101
GRAND JUNCTION, COLORADO 81506
PHONE: [phone], FAR 242-7908
MINE ENGINEERING
MINE RECLIUMTION
July 10, 1995
A. J. Waldron
Division of Minerals and Geology
1313 Sherman St., Room 215
Denver, CO 80203
Re: Somerset Mining Company
East Yard Pond - TR-026
Permit No. C-81-022
Dear Mr. Waldron:
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CIVIL ENGINEERING
CONSTRUCTION MANAG
~'~~EIVED
JUL 121995
Division o~ ~~~i~~erals & Geology -
The Division's letter dated June 14, 1995 transmitted its adequacy
review for the referenced technical revision. The intent of the
technical revision was to address a concern you expressed during a
recent field inspection regarding the spillway configuration of the
east yard pond. Specifically, you noted the crest elevation of the
primary and emergency spillways were not separated by the required
one foot as required by Rule 4.05.6(4). The Division developed
additional questions and concerns about the design of the east yard
pond during its review of the technical revision. Following are
Somerset's responses to the Division's concerns:
1. The run-off volume from the 25-year event is presented on page
B-38. The 25-year 24-hour event produces 10,236.67 cubic feet
of run-off volume. The soil loss calculation presented on
page B-39 produces a 3 year sediment storage volume of 2000.28
cubic feet. The maximum sediment and water level from the 25-
year event is presented on the staging chart on drawing ES-
3404. The revised drawing C8-1166 submitted with the original
technical revision application should be disregarded since
this information is now presented on revised map EB-3404.
2. The run-off volume from the 10-year event is presented on page
B-38. The 10-year 24-hour event produces 6,349.96 cubic feet
of run-off volume. Since the pond will contain the run-off
from the 25-year event, the water level generated from the 10-
year event was not shown on drawing E8-3404. The information
presented on new page B-39a shows that the emergency spillway
should be upgraded to a 12" CMP.
Somerset does not believe the entire hydrologic design of the
east yard pond needs to be amended. The hydrologic design
presented on pages B-35 through B-39 has been a part of the
approved permit document for 14 years. The east yard pond has