C153445 Feasibility Study

• Contract/PO #: C153445
• Contractor Name: Summit Reservoir and Irrigation Company
• Contract Type: Loan
• Water District: 32
• County: Montezuma
• Bill Number: HB 84-1128
• Loan Projects - Doc Type: Feasibility Study

The criteria for design of the filter blanket are well
established and can be expressed by the following equations.

1 )

Filter Criteria

D15 (Filter)
DS5 (Soil)

is less than 4 or 5

2) Filter ~ermeability D15 (Filter) is greater than 4 or 5
D15 (Soil)

3)

Drain Pipe Criteria

DS5 (Filter)
HOle Diameter is greater than 1.0

Use of the above criteria will result in a conservative'
design that,will provide adequat.e safety margins even under the
worst conditions. The filter blanket proposed for Summit must
cover both the embankment and the foundation because both are
seeping; therefore, the criteria will be applied to both.

The filter will consist of ASTM C-33 sand which is a univer-
sal filter material with characteristics listed below.

ASTM C-33
Sand Sieve Analysis'

Sieve No.
3/4"
#4
#8
#16
#30
#50
#100

Percent Passinq'
100
95-100
80-100
50-85
25-60
10-~0
2-10

The D1 of C-33 sand is 0.30 millimeters (mm) for the worst
end of the Jesign range. The D85 of the embanKment and foundation
of the south dike (see Table V-A) are 4.0 mm and 0.074 mm respec-
tively. The following calculations result: .

D1S (Filter)

D8S (Embankment)

D15 (Filter)

D85.'(FOundation)

=

~ = 0.075
4.0
.~ = 4.05
0.074

=

The C-33 sand easily meets the criteria for
but just meets the criteria for the foundation.
equations is very conservative the C-33 sand can
fiiter blanket with confidence.

the embankment
Since use of the
be used for the

The filter must carry the woter that seeps through or under
the dike .so the permeability of filter relative to the foundation

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