WSP12402

• File Number: 8443
• Description: Narrows Project
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 2/1/1978
• Author: Woodward-Clyde Consu
• Title: Review Of Data And Studies Developed By The Bureau Of Reclamation For The Feasibility Stage Design Of Narrows Dam Colorado
• Water Supply Pro - Doc Type: Report/Study

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Woodward.Clyde Consultants

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existance of weak layers and swelling materials should be

thoruughly investigated.

The density parameter for the Pierre formation for our

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stability analyses was based on density data determined by the

(Ref. 14). Based on our replot of

above drill hole

Bureau of Denison samples obtained

he direct shear data

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(Ref. 14) for the residual strength

siltstone

(CL) cores tested by the Bureau

shear test results on the CH s

from the test hole at the

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railroad bridge relocation 1 c io~ef. 10), we selected the

shear strength parameters give ~ ~e 2. We do not know if

an effort was made to orient appare~ak laminations in the

formation with respect to ~ e plane selected in the

direct shear tests. Fro ~~a results of density, water

content and specif' r the above samples, it is

.

I

indicated that "/~

- .----th"LL IIdturat s~

Considera ~ the strength factors for the Pierre

formatio~~ w argely based on laboratory tests on

sample rom the1\e Denison sample hole recently drilled. We

area,,~~t~ and examine any weak layers in the formation,

if in fact suc layers exist. In addition, the swelling

were saturated

in

.

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potential at structure sit~s should be studied in detail. We

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have some concern that excessive erosion could occur on an

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I/D;.
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