PERMFILE49711

• Permit No: M2005066
• IBM Index Class Name: Permit File
• Doc Date: 4/6/2006
• Doc Name: Adequacy Response
• From: Banks and Gesso LLC
• To: DMG
• Media Type: D
• Archive: No

Ms. Erica Crosby April 5, 2006
Division of Minerals and Geology Page 18 of 21
• Is the ditch hydrologically connected to the shallow alluvial aquifer?
Average seepage losses in the reach extending from WCR 4.5 to WCR 6.
• Schematic showing the elevation of the ditch, ditch invert, ditch water level,
ground surface elevation at Phase 1, and groundwater elevation at Phase 1.
(Response from Martin and Wood Water Consultants, Inc.)
The Brighton Ditch is owned and maintained by the Brighton Ditch Company. There
are 20 shares of the ditch, owned by a number of entities (including Asphalt Paving
Company -see Attachment 4). The Brighton Ditch is unlined in the vicinity of the
Wattenberg West pit.
The ditch typically begins diverting in April, although in recent years (1994 - 2002
period) there have been seven years when diversions commenced in March. The
annual diversion from the South Platte River have averaged 9,426.7 acre-feet for the
period 1950 to 2002. The maximum and minimum annual diversions during this
same period were 14,076 acre-feet and 6,422 acre-feet, respectively.
The ditch is not hydrologically connected to the shallow alluvial aquifer. The
available data indicates that the ditch, located on a small terrace above the alluvial
plain, is well above the recorded water levels in the alluvial aquifer, based on the
borehole data taken from holes along the western edge of the proposed mine area
and topography (see Attachment 10 for a schematic showing across-section of the
ditch relative to Phase 1 and the water table).
For the entire 8-mile length of the ditch, the seepage losses have been estimated to
range from 15- to 25-percent of the headgate diversions. The Brighton Ditch
Company has, for its purposes, adopted the 25-percent loss figure that was
developed by Martin and Wood in the early 1990's. This would equate to an
average loss of 3.1-percent per mile, although it is noted that the losses along the
run of the ditch would not be expected to be consistent, as the amount of water
flowing in the ditch at any point along its run, and thus the stage in the ditch, would
have a bearing on the amount of loss. There has not been, to our knowledge, any
segment-by-segment analysis of the loss carried out to date. To determine the
losses in the specific segment identified in the DMG request, an analysis of the
diversions upstream of this reach and the resultant flow in the ditch along this reach
would have to be carried out.
7. In accordance with Rule 6.4.7(2)(b), please characterize the shallow alluvial aquifer
and include a discussion of the direction and rate of groundwater movement in the
Wattenberg West project area and surrounding area. Please respond.
(Response from Martin and Wood Water Consultants, Inc.)
The alluvial aquifer at the Wattenberg West site and underlying the Town of
Wattenberg is comprised of a typical saturated sand and gravel alluvial deposit. The
depth of the alluvium ranges from approximately six feet on the far west edge of the
site to approximately 40-feet in the vicinity of the WIA supply well. Depth to water