REP20168

• Permit No: C1981028
• IBM Index Class Name: Report
• Doc Date: 4/7/1986
• Doc Name: IRRIGATON TR KEENESBURG MINE FN C-81-028
• From: MLRD
• To: RANDY PRICE
• Permit Index Doc Type: REVEG MONITORING REPORT
• Media Type: D
• Archive: No

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Richard D. Lamm
Governor
DATE:
DEPARTMENT OF NATURAL RESOURCES
David H. Getches, Executive Director
MINED LAND RECLAMATION DI\
DAVID C. SH ELTO N, Director
April 7, 1986
T0: Randy Price
FROM: Dan Mathews ~~l/,
RE: Irrigation Technical Revision, Keenesburg Pline - File No. C-81-028
As I understand the above referenced technical revision application, Coors is
requesting to modify their irrigation plan from the currently required 9"
effective irrigation to a schedule which would require 1.5 effective
irrigation each of thg first two weeks after seeding, followed by second
irrigation period beginning 3 to 5 weeks after the end of the first period.
The second irrigatipn period would be coordinated with precipitation and would
begin only after a 1.5 ~ water deficit has developed. Approximately 1" of
effective irrigation or precipitation would need to be applied each week for
two weeks during the latter period. I have the following comments.
The assessment presented by Dr. Stednick contains sufficient technical
justification for the proposal. The plan will require less irrigation
water than previously, but will require more intensive monitoring of
precipitation and irrigation water application on the part of Coors. The
application should contain a specific plan for monitoring and recording
precipitation and irrigation water application.
2. There is considerable doubt as to whether Coors can continue to use well
L~'H - 2 for irrigation due to apparently deteriorating water quality
(EC>7 mmhos and SARA 20). However, the application indicates that there
may have been some problem with sample procedure on the recent LFH-2
analysis, and that a subsequent sample would provide more accurate
information. Unless we receive and have an opportunity to review the
analysis of the most recent sample our proposed decision should prohibit
the use of LFH-2 water for irrigation. The statement in the proposal
regarding LFH-2 that "If there is an improvement in quality this well
will be used in 1986..." is to vague. LFH-2 water should be used only if
ii; is as good or better quality than other available water.
The current approved seeding season at Keenesburg is April 15 through
May 15. Seeding at this time is designed to take maximum advantage of
stored soil moisture and the April-June precipitation peak. I would
r'gcommend against extending the seeding period further into the summer
because the high evaporation rates and low precipitation in most years
would require significantly more irrigation water application. Seeding
any earlier than April 15 would not be recommended, because ward season
grasses would not be expected to germinate much earlier than that in most
years.
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]
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