PROJ02070

• Contract/PO #: C150233
• Contractor Name: Tom Hill
• Contract Type: Loan
• County: Grand
• Loan Projects - Doc Type: Feasibility Study

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SEOTIIIIFOUR

Background InformationT

4.6.1 Physical and Index Properties Tests

Laboratory tests were conducted to identify index properties and classify materials according to
the Unified Soil Classification System (USCS). The index property testing included gradation
analysis, hydrometer analysis, water content, and Atterberg limits.

The embankment sample classified as fat clay (CH) with some sand and trace gravel. Gradation
and hydrometer analyses indicated the sample had 5.3 percent gravel, 18.9 percent sand, 75.8
percent fines of which 41 percent was clay sized (less than 0.002 millimeter). The moisture
content was 19.1 percent with a plasticity index of37 and a liquid limit of 56.

4.6.2 Engineering Property Tests

Laboratory tests that were performed to characterize the engineering properties of the
embankment sample included compaction test, triaxial compression tests, and permeability test.

Standard compaction test (ASTM D 698) results indicated an optimum moisture content of 19.3
percent and a maximum dry density of 103.5 pounds per cubic foot (pct).

Isotropically consolidated undrained triaxial compression tests (CIU') with pore pressure
measurements were performed to evaluate the effective and total stress friction angles of the
embankment material. One CIU' triaxial test series (three test samples) was completed at
effective confining stresses of 15,30, and 60 pounds per square inch (psi). The samples were
compacted to 95 percent of the maximum dry density. The resulting shear strength envelope
shows an effective stress friction angle of about 22.3 degrees with 410 pounds per square foot
(pst) cohesion and a total stress friction angle of about 8.7 degrees with 840 psf cohesion.

Permeability test was performed on the CIU' sample tested at an effective confining stress of 30
psi. The resulting permeability was 4.2 x 10-9 centimeter per second (cm/s).

'URS

T:\PROJECTS\22238900_MCELROY_DAMlCWCB LOAN FEASIBILITY REPORT DRAFT.DOCl11-OCT -06\22238900IDEN 4-2