WSP05308

• File Number: 8111.810
• Description: Arkansas River Compact Administration - Clay Creek
• Basin: Arkansas
• Date: 1/1/1964
• Author: H. E. Eyrich
• Title: Clay Creek Seepage
• Water Supply Pro - Doc Type: Publication

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II,\.HoLD E. EYUICH
CONSULTING E"NGfNEER

PHONE': WEST 4-1465
1660 SO. KING STREET

DfNVERI9,COLORADO

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It was further assumed that one-half of this material was available
to the surface on the left side or the side that is in question so
far as feeding an acquifer to the well fields supplying Lamar,
Colorado. The volume of siltation on the left side, on this oasis,
would be 2,880 000 cubic feet. The thickness of si~t was assumed
to be u.41 cUbic feet if in a solid condition; however, a void ratio
study on this same material, assuming a dry density of ,0 pounds per
cubic feet, would yield a total thickness of 1.38 feet of silt over
this portion of the reservoir basin. In assuming that one foot re-
mained on the top of the existing surface and that 0.38 feet was
available for permeation and, further, assuming that one-half of this
material was deposited in the first foot, then 0.113 feet of material
would be available to fill the voids. In-place density tests on ma-
terials in this region indicate that it has a dry density of 101
pounds per cubic foot and a specific gravity of 2.70. On this basis,
the total volume 01' solids would go from 0.60 to 0.713, which would
yield an alternate dry density of 113 pounds per cubic foot, which,
in turn, wuld alter the coefficient of permeablli ty - from 400 feet
a year ta 0.9 feet per year. After the first year's operation, it
Was further assumed that one-half of the secondary siltation would
still occur in the first foot of material, which, in turn, would
increase the height of solids to 0.769, whiCh, in turn, would yield
an equivalent dry density of 130 pounds per cubic foot. At this final
density and void ratio, the materials could be assumed to be impervi-
ousi that is, to have a ooefficient of permeability in the order of
0.OU01 feet per year.

In order to develop an operational study, it Was assumed
that the initial filling of the reservoir would be by a high runoff
flood condition that would contain a 15 per cent silt burden of whioh
one-fourth would be deposited. It was further assumed that of 2900
acre-feet of material, 43, acre-feet times one-fourth, or 139 acre-
feet of silt would be deposited within the basin.. The total area ot
the reservoir is in the order of 286 acres. Assuming that the silt
burden had a dry density of 50 pounds per cubic toot, then the height
ot solids would be in the order of 0.300 feet. It was further assumed
that 15 per cent of this material would be absorbed in the first foot,
which would yield a dry density in the magnitude of 109 pounds per
cubic toot, which, in turnt would develop a coefficient ot permeabil-
ity in the magnitudeot 7 reet per year after the first tilling by a
flood. The aforementioned redUction ot permeability to 0.9 feet per
year was assumed to result at the end of the first year's operation.

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