2012-09-06_REVISION - M2008070 ‎(22)‎

• Permit No: M2008070
• IBM Index Class Name: REVISION
• Doc Date: 9/6/2012
• Doc Name: AM-01 APPENDIX C: HYDROGEOLOGY & HYDROLOGIC INNFORMATION
• From: WESTERN GRAVEL
• To: DRMS
• Type & Sequence: AM1
• Email Name: THM
• Media Type: D
• Archive: No

From the information collected and with consideration of the effects of
variations in well construction, approximate potential well yields in the
study area can be estimated. Southeast of Meeker, in Agency Park, where the
saturated thickness exceeds 100 ft, efficiently constructed, screened wells
that fully penetrate the aquifer can be expected to yield on the order of
1,000 gal /min for sustained periods of time. Shallower wells can be expected
to yield from 100 to several hundred gal /min. West of Meeker, where the aver-
age saturated thickness of the aquifer is 15 to 20 ft, efficiently constructed,
screened wells can be expected to yield on the order of 100 gal /min for sus-
tained periods of time. Relatively inexpensively constructed wells can be
expected to yield 50 to 100 gal /min for a few minutes and 25 gal /min or less
for sustained periods of time.
Transmissivity of the White River alluvial aquifer in the areas tested
ranges from about 860 to about 93,000 ft /d. Hydraulic conductivity of the
aquifer in the areas tested ranges from about 70 to about 1,550 ft /d. Trans -
missivity and hydraulic conductivity values indicated by aquifer testing in
Agency Park are much greater than values obtained from tests conducted else-
where in the study area.
In general, hydraulic conductivity decreases to the west as the valley
slope lessens and the low - energy environment of deposition results in more
fine - grained sediments being deposited. Transmissivity is greatest where the
saturated thickness of the alluvium is large and in the eastern part of the
study area and least where the saturated thickness of the alluvium is small and
in the western part of the study area. Transmissivity values are expected to
be relatively large in the western part of Powell Park, where the saturated
thickness of the alluvium is greater than 90 ft.
The estimated total volume of water in storage in the White River alluvial
aquifer in the study area, based on the areal extent, saturated thickness, and
an assumed average specific yield of 0.2, is 103,000 acre -ft. Southeast of
Meeker, about 40,000 acre -ft of water are in storage in the alluvial aquifer.
Based on 13 samples, ground water in the eastern part of the study area is
a calcium bicarbonate type; to the west, the ground water is a sodium sulfate
type. Water in the aquifer is classified as very hard throughout the study
area. Water - quality standards for public -water supplies for dissolved solids
and sulfate are exceeded west of the confluence of the White River and Piceance
Creek and in one well located on an alluvial fan emanating from rocks of the
Mesaverde Group at the Grand Hogback. The recommended limit for concentration
of iron in public -water supplies is exceeded at the Deserado coal -mine site.
Dissolved - solids concentrations were compared with specific- conductance values
for those samples for which both measures exist; waters with specific conduc-
tance exceeding 745 pmho have dissolved - solids concentrations in excess of the
recommended standard of 500 mg /L. Specific conductance from 115 samples of
water from the White River alluvial aquifer ranges from 400 to 14,000 pmho.
Smallest values were measured at the eastern end of the study area in Agency
Park and largest values were measured at the western end of the study area near
Rangely. Average specific conductance of ground waters sampled west of the
confluence of the White River with Piceance Creek is more than twice the aver-
age value obtained east of that confluence. The specific conductance of water
from wells close to the White River is less than that from wells farther from
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