REV04891

• Permit No: C1981038
• IBM Index Class Name: Revision
• Doc Date: 3/27/1991
• Doc Name: PN C-81-037 TR 90-11 WEST RIDGE WASTE DISPOSAL AREA DRAINAGE CONTROL PLAN MODIFICATION
• From: CYPRUS ORCHARD VALLEY
• To: MLRD
• Type & Sequence: TR11
• Media Type: D
• Archive: No

C c~~us
orcna~a veu®y
~~II~~II~'~~II~~'~~
999
Cyprus Orchard Valley Mine
P. O. Box 1299
Paonia, CO 81428
Phone: [phone]
Fax: [phone]d
March 14, 1991
Carl Mount
Reclamation Specialist
Colorado Mined land Reclamation Division
215 Centennial Building
1313 Shen~arr Street
Denver, Colorado 80203

MAR 2 7 1991
Mined Land
Reclamation Division
RE: PERMIT N0. C-81-038: 4'ECI-aTICAL REVISION 90-11, WEST RIDGE WASTE DISPOSAL
AREA ~2A'Lt,F~GE OONIROL PLAN MODIFICATION
Dear Carl:
In response to adequacy comments *~*~~~ TR-11 received 2/28/91, the following
information is sulmitted along with the enclosed revised materials.
Coatumnt 1: Rile 4.09.2(7) wrn~;we all surface runoff frun the area above the
waste pile to be diverted away frao the fill and into stabili2ed
diversion cr,~.,*,or s designed to pass safely the runoff fnm at least
the 100-year, 24-hour precipitation event. We cannot find designs
for or evidence of any plan for this required diversion.
Reply 1: 'Itrv changes are prrpposed to provide oong~lianoe with Rile 4.09.2(7).
Surface runoff from the area above the waste pile will be diverted
as follows: channel EE will be reconfigured to convey runoff frvn
the 100-year, 24-hour precipitation event, and culvert P will be
sealed with a concrete plug. ~n~r EE has been designed to
include floras formerly routed thrrouc~r culvert P. 'These changes have
been incorporated into the permit on revised page 37A aryl Map No. 8-
l has been revised to exhibit the sealing of culvert P.
Sealing culvert P may result in the impaurbnem of a small quantity
of water in the iiate vicinity of advert P and the sewage water
treatment plant. Calaalations based upon a recent survey of the
area are enclosed aryl demonstrate the existing available storage
capacity for this water is more than adequate to fully contain the
projected 100-year, 24-hour runoff volume fr'an the sewage treatment
plant drainage area. Rtmoff volume for the 100-year, 24-hour event
in this area is calarlated to be 1280 ft3. Available storage volwne
is calculated to be 2490 ft3. CnVOC will maintain adequate storage
volume to fully contain the 10o-year, 24-hour precipitation event
runoff at all times by pump evaa~atirg water fran this area to
c~raruiel EE as required.