GENERAL49395

• Permit No: M1977436
• IBM Index Class Name: General Documents
• Doc Name: TERMPORARY SUPPLY PLAN
• Media Type: D
• Archive: No

INTRODUCTION
The Riverdale/Tower Pit #l operation is located southwest of Brighton in the SE l/4 of Section 14,
T1S R67W, 6th P.M. It is bounded to the east by the South Platte River and to the west by the
Brantner Ditch and Riverdale Road (Figure I).
The site consists of 122 acres of land. The mine plan calls for the development of two pits, located
approximately 100 feet from the South Platte River. The North Cell pit is currently 20.65 acres with
maximum development of35 acres. The proposed South Cell pit will be constructed when resources
are needed, at least three years from now, and will extend across 29.5 acres at maximum
development. Figure 2 shows the current and maximum developed North Cell pit.
Both pits are on wet alluvial land and moderately wet loamy alluvial land adjacent to the South Platte
River. The loamy alluvial land has a high water table, and the available water capacity is high, ranging
from 0.16 to 0.20 inches per inch of soil. The wet alluvial lands are wet at a depth of 2 feet most of
the time, and are wet to the surface throughout the growing season. The average water capacity is
too variable to be estimated.
This Temporary Supply Plan covers evaporation from full development of the North Pit, and the
water consumed in the wet sieving process. Temporary pumps are capable oftransferring a maximum
of 10,000 gpm 60 percent of the day from the North Cell back into the South Platte River. The
wash/sieve cycle utilizes 800 gpm ]0 hours/day, 5 days per week, and approximately 4 percent ofthe
water leaves the site on the product. D. H. Holding proposes to replace water lost from evaporation
and product loss with augmentation waters available from Groundwater Appropriators of the South
Platte (GASP).
The following analysis describes the various assumptions that were developed for depletions and
replacements. Evaporative losses, stream depletions, and consumption associated with product loss
are described in the depletion section. The use of GASP controlled waters will be described in the
replacement section.
DEPLETIONS
Evaporative Losses
The gross annual evaporation, taken from the NOAA Technical Report NWS 33, Evaporation Atlas
for the Contieuous 48 United States, is 43 inches at the site. The annual average precipitation at the
site is 14.29 inches per year, as determined from the monthly climatic data from the Brighton weather
station (Station 50950), which is the closest station to the site (Attachment 1). Evaporative losses
at the North Cell pit are summarized in Tabte I.
Stream Depletions
Stream depletions caused by well pumping were estimated using the Analytical Stream Depletion
Model, published in 1987 by the Colorado Division of Water Resources. The maximum pumping rate