PROJ00143

• Contract/PO #: C153810
• Contractor Name: Wood Lake Mutual Water & Irrigation Company
• Contract Type: Loan
• Water District: 1
• County: Weld
• Bill Number: SB 97-008
• Loan Projects - Doc Type: Feasibility Study

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A.2.1 Scone Of Services

The scope of service for this geotechnical investigation was limited to:

I. Advancement of four (4) borings through the main dam embankment to depths up to 30-
feet below the ground surface with soil samples obtained during drilling;

2. Visual classification of soil samples obtained;

3. Laboratory testing of soil samples; and,

4. Surveying of the dam embankment.

A,2.2 Subsurface Exnloration Procedures,

The borings were advanced with a CME,75 drill rig using both a 3-1/2I.D. hollow stem auger and a 4,
inch O.D. continuous flight auger. Disturbed and relatively undisturbed samples were recovered from the
borings for use in visual classification (ASTM D-2488) in the field and for future laboratory testing.

Disturbed soil sampling was performed in accordance with ASTM D-1586, Standard Penetration Test
(SPT). Using this procedure, a 2" outside diameter split-barrel sampler was driven into the soil by
successive blows of a 140'pound weight falling 30". After an initial set of 6", the number of blows
required to. drive the sampler an additional 12" was recorded as the "penetration resistance" or "N value".
The N value is an index of the relative density of cohesionless soils and the consistency of cohesive soils.

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A limited number of undisturbed soil samples were recovered by use of 2Ih,inch diameter thin walled
Shelby tubes in accordance with ASTM D 1587. These samples are relatively undisturbed and can be used
for strength and consolidation testing.

As the samples were obtained in the field, they were visually classified by an Engineer from SMITH
GEOTECHNICAL. Representative portions of the samples were then returned to the laboratory for further
examination and verification of field classification. Boring logs, indicating the depth and identification of
the various strata, the N-value, water level information, and pertinent information regarding the method
for maintaining and advancing the drill holes, are included in Appendix B. Charts illustrating the soil
classification procedure, and descriptive terminology and symbols on the Boring Logs are also included
in the Appendix B.

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A.2.3 Subsurface Conditions.

The following is a brief description of the various layers of soil and/or rock encountered. All depths given
are relative to the ground surface at the time of drilling. The detailed boring logs are included in the
Appendix and should be consulted for specific descriptions of the soil conditions encountered,

(I) Dam Embankment Fill: The dam embankment fill consists of silty sand and sandy clays
from the ground surface (dam crest) to up to approximately eighteen (18) feet below

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