WSP08422

• File Number: 8200.760
• Description: Yampa River General
• State: CO
• Basin: Yampa/White
• Water Division: 6
• Date: 1/1/3000
• Title: Yamcolo Reservoir Geotechnic Data
• Water Supply Pro - Doc Type: Report/Study

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in the "Yamcolo Damsite Geological Exploration Report", November,

1977. Logs of borrow area test holes not included in the above

report are presented in APPENDIX A along with a location map.

Materials Classification.

Mechanical gradations along with plastic and liquid limits were

performed on samples taken from all the test pits excavated in

foundation and borrow areas. The results of these tests on found-

ation samples were presented in the Geological Exploration Report

and results from borrow areas are presented in APPENDIX A. Four

distinct materials were considered: 1) Clay-shale gravel from

spillway excavation and the left abutment; 2) glacial clay gravel

from the foundation and right abutment; 3) glacial-clay-gravel

from the main borrow area, and; 4) glacial outwash gravel from a

pit approximately 4 or 5 miles downstream from the dam site. The

material from the spillway excavation will be used to form an

impervious Zone 1 section in the interior of the dam. The material

from the main borrow area will be used for a Zone 2 outer shell.

The glacial outwash gravel will be transported to the site for

use in internal drainage filter, and as bedding filter, and as a

possible concrete aggregate source. Samples were selected from

each of these types of materials, which were representative of the

average for each type, for further testing. Hydrometer gradations

were performed on these samples (except the gravel outwash) along

with moisture density curves (ASTM D-698). The results of these

tests are presented in APPENDIX B.

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