1987-12-01_PERMIT FILE - C1981017 ‎(280)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Process Flow Description
• Section_Exhibit Name: Chapter IV Attachment B
• Media Type: D
• Archive: No

• July 14 , 1986
Ms. .Candace Thompson
Mined Land Reclamation
1313 Sherman St. , Room 423
Denver, CO 80203
RE: Technical Revision - Savage Pond Permit, C-017-81
Dear Candace ,
In reviewing - my calculations for. the Savage Pond removal
request, I noticed that a mistake had indeed been made in
determining the peak flows for a ten year and 25 year -event.
This error was due to the usage of wrong slope interpolation
factors . After recalculating',' I have come up with the fol-
lowing values , which agree with yours, and should supersede
the values listed in our technical revision dated June 19 ,
-.�.
1986 . '
AREA DISTURBED CN SLOPE :;:SLOPE PEAK DISCHARGE r
ACREAGE INTERPOLATION TABLE S-lA (SCS)
FACTOR cfs7 in runoff
1 11.63 93 11.1 .96 20.0 Z
lA 7.23 75 8.0 .92 12.5
2 3.49 90 6.5 1.06 5. 7 FS
• -I RUNOFF TABLE S-3 (SCS ) PEAK DISCHARGE (cfs)
(cont. ) 10 yr. 24 hr. 25 yr. 24 hr. 10 yr. 24 hr. 25 yr. 24 hr.
1.22 1.50 .23 .4 28 .8
: 33 .48 3.8 5.5
1:01 1.27 6.1 - 7. 7
33 .3 ,f's Total: 42 .0 cfs
The existing spillway at the Savage Pond is a tee-shaped 18"
dia. CMP set on a 10% grade. This culvert can handle a flow
of 18 cfs. This is more than enough to handle the 7. 7 cfs of
flow generated during a 25 yr./24 hr. event in Area 2.
The existing primary spillways on the four ponds known as
. Discharge Point 001 are 18" dia. CMP set -.on a 10% slope.
These culverts can also handle a flow of 18 cfs . The emer-
gency spillways are ten ft. wide by two -.ft. ,-deep trapazoidal
channels lined with riprap. The enclosed calculations show
that these channels can handle a 25 yr./24 hr. event.
If you have any more questions concerning this technical
revision, please feel free to contact me here at the mine.
Sincerely,-
Scott Jones , Environmental Engr.
enc.
SJ/sj