WSP02105

• File Number: 8200.765
• Description: White River General
• State: CO
• Basin: Yampa/White
• Water Division: 6
• Date: 5/1/1986
• Author: Morrison-Knudsen
• Title: White River Geotechnical Study - Final Report - Volume I
• Water Supply Pro - Doc Type: Report/Study

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OD1105

Preliminary site screenings were carried out for the upper canyon section of
the river and for the Powell Park site. The upper canyon sites considered in
thi s eval uati on were Warner Poi nt, Choke Cherry, Dry Creek, three axes at
Veatch Gulch and Canyon. From these, Warner Point and one of the Veatch Gulch
sites were selected for sub-surface investigation. Two Powell Park axes and
the Smith Gulch axis were screened in the Powell Park area. The furthest
upstream axis at Powell Park was chosen for subsurface investigation.

Detailed site-specific geologic mapping was carried out at each dam site.
This consisted of locating exposed bedrock outcrops, mapping lithologic
contacts, and descri bi ng weatheri ng and j oi nti ng patterns that mi ght affect
the stability and permeability of the dam foundations.

Sub-surface foundation investigation at the selected dam sites included auger
hol es, cased rotary hol es and test pi ts at lake Avery, and rotary hol es at all
other sites. Borehole penetration and permeability tests were performed
systematically in all drill holes. Soil samples and rock core were logged and
photographed as they were drilled. Samples of foundation material were
sel ected for laboratory testi ng as necessary. Sei smic refracti on surveys of
foundation substrata were carried out at all sites.

Potential borrow areas for construction material were investigated by auger
holes and by test pits. The holes and pits were logged and samples were
obtained for laboratory testing at each area.

During the initial drilling at the Warner Point site, it became apparent that
the depth-to-bedrock in the river channel and the left abutment was deeper
than had been expected. A re-assessment of the scope of the investigation was
considered. It was decided jointly between MKE and the CWCB that, considering
the objectives of the study, it would be advisable to gather information on as
many sites as possible. Therefore, the Choke Cherry and Veatch Gulch sites
were added to the subsurface investigative program.

Tabl e El summari zes, in quanti tati ve terms, the subsurface i nvesti gati on at
each site:

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