HYDRO31064

• Permit No: M1980244
• IBM Index Class Name: Hydrology
• Doc Date: 5/23/1997
• Doc Name: MEETING AGENDA
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources ~~~~~
1313 Sherman SI . Room 215
Denver, Colorado 80203
Phone: [phone]
FA%:13071 832-8106
DEPARTMENT OF
NATURAL
RESOURCE
DATE: May 22, 1997 co~er~no~r
lames 5 Lochhead
TO: Bruce Humphries, James Stevens and Harry Posey Executive Director
Michael B. Long
FROM: Berhan Keffelew Dmsion Dueaor
RE: Hydrology items to be considered by CC&V consultants
during modeling exercise
1) The entire watershed that will contribute water to each area to
be included in the model. If the entire watershed is not going to
be considered, consultants have to show why it should not be
considered. If management practice has been implemented to limit
or decrease the size of the watershed, it has to be explained in
detail to show the management practice and its effectiveness. When
considering the watershed, the following has to be considered:
Volume Parameters
A) Soil type: Infiltration and percolation rates for each
type.
B) Cover type: Vegetated or not vegetated, rock cover,
etc.
Time Parameters (These to determine the time of concentration)
A) Slope of the watershed.
B) Flow length of the watershed.
C) Surface roughness.
2) In addition the consultants have to include the flow rates from
the Moffat Tunnel which has a base flow of approximately 5 to 10
gpm and in the spring has been noted to flow as high as 550 gpm.
3) Flow from the Roosevelt Tunnel and infiltration rates from
Arequa and Squaw Gulch. Granted Squaw Gulch does not have a base
flow, but it does flow during the spring and summer precipitation
events.
NOTE: The Division is well aware of the fact that the annual
precipitation for the area is 18 inches, however, the past two
years it has averaged about 30 inches. The consultants have to
consider these factors and adjust those numbers accordingly.