PROJ00382

• Contract/PO #: C153685
• Contractor Name: Monument, Town of
• Contract Type: Loan
• Water District: 10
• County: El Paso
• Bill Number: SB 94-029
• Loan Projects - Doc Type: Feasibility Study

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Chapter III . Background Information

These borings were advanced with a 4.25-inch LD. (inside diameter) hollow-stem auger
that was powered by a Mobile B57 truck-mounted drill rig. Standard penetration test blowcounts
and samples were taken at typically 5-foot intervals in the borings. The borings were drilled to
the top of bedrock, and the depths are presented in Table ID-2.

Tabl~ III-2
Bedrock Depths

Boring Bedrock Depth (ft) 1
BIOI 50.5
BlO2 51.0
BI03 15.5

During drilling, the water level in each b\Jrehole was observed. In addition, Boring B 101

and B 103 were converted into temporary observation wells after completion of the holes. Upon

completion ofB102, the hole was backfilled with concrete sand.

The embankment fill encountered in Boring B 101 and B I 02 consists of about 41 feet of
silty sand (SM, SW-SM), silty gravely sand (SM:, SW-SM), and clayey sand (sq. Overall, the
permanent fill material in the embankment dam is the silty sand and silty non-plastic fines, and
containing approximately 5 to 20 percent fine gravel. Zones of clayey sand (SC), with
thicknesses ranging from 2 to 5 feet, were encOuntered in the embankment. The clayey sand
consists of fine to coarse sand, with approximat~ly 30 to 45 percent medium-plastic fines, and
approximately 0 to 15 percent fine gravel. The ~tandard penetration resistance blowcounts of the
embankment fill range from 6 to 21, with and aVerage of 14. The fill materials are considered to
be medium dense.

The foundation soil encountered in all three borings consists of approximately 7 to 8 feet

of sand and gravelly sand (SM, SW -SM). Thes~ materials are mostly medium to coarse sand,

with approximately 5 to 15 percent non-plastic fines and approximately 10 to 25 percent fine to

medium gravel. Limited standard penetration resistance taken in the foundation soil stratum

indicates that the foundation soil is very loose to medium dense, with blowcounts ranging from :i

to 20, and with an average of9.

Monument Lake Dam Feasibility Study