HomeMy WebLinkAboutObservation of Excavation Report.pdfHEPWORTH - PAWLAK GEOTECHNICAL
October 31, 2012
C and B Development
Attn: Matt Cox
260 Woodruff Road
Glenwood Springs, Colorado 81601
(cbc@sopris.ner)
Hepvcunh-Panvlak Geotechnit:d, Inc.
5020 Comm Rs and 154
Glenwood Springs, Color N1601
Itunc: 970.945-7Q5
Far 970-945.8454
emwl: hpceo3hpeeotech.com
Job No. 112 295B
Subject: Observation of Excavation, Proposed Residence, Lot 82, Filing 7, Elk
Springs, 1866 Elk Springs Drive, Garfield County, Colorado
Dear Matt:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on October 30, 2012 to evaluate the soils exposed for
foundation support. The findings of our observations and recommendations for the
foundation design are presented in this report. We previously conducted a subsoil study
for design of foundations at the site and presented our findings in a report dated
September 25, 2012, Job No. 112 295A.
The proposed residence is essentially the same as described in our previous report except
that a partial basement area has been added in the northwestern part of the residence
living area. The garage at the west end and the basement will have a slab -on -grade floor.
Footings designed for the recommended maximum bearing pressure of 2,000 psf are
proposed for the building support.
At the time of our visit to the site, the foundation excavation had been cut in multiple
levels from 1 to 8 feet below the adjacent ground surface with typically 1 to 3 feet
between levels. The soils exposed in the bottom of the excavation consisted of basalt
rock in a calcareous silt matrix essentially throughout the residence living area and brown
porous clay in the garage area. Our previous Pit 1 encountered 8 feet of the brown clay
below natural ground surface overlying basalt rock soils. There was considerable loose
material in the excavation bottom due to basalt rock removal and in the clay garage area
apparently due to its loose condition. Results of swell -consolidation testing performed on
samples of the brown porous clay taken from the garage site, shown on Figure 1, indicate
the soils have low compressibility under low natural moisture and light loading with a
low to moderate collapse potential (settlement under constant load) when wetted, and
high compressibility under additional loading. No free water was encountered in the
excavation and the soils were slightly moist.
The soil conditions exposed in the excavation are consistent with those previously
encountered on the site and the basalt rock with calcareous matrix soil is suitable for
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