HomeMy WebLinkAbout17-7-134.01 (08-09-18) Exc Obs signed.pdf mAR5020 County Road 154
Glenwood Springs, CO 81601
Geotechnical Engineering I Engineering Geology Phone: (970)945-7988
Materials Testing I Environmental Fax: (970)945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver(HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs,Summit County, Colorado
August 9, 2018
Coleman Custom Homes
Attn: Alex Coleman
P. O. Box 4724
Edwards, Colorado 81632
alex@cchvail.com
Project No. 17-7-134.01
Subject: Observation of Excavation, Proposed Precourt Residence, Lot 1, Bighorn Estates,
4298 Nugget Lane, Vail, Colorado
Dear Alex:
As requested, a representative of H-P/Kumar observed the excavation at the subject site on
August 2, 2018 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations for the foundation design are presented in this report. The
services were performed in accordance with our agreement for professional engineering services
to Amanda Precourt, dated December 15, 2016.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated September 12, 2017, Project No. 17-7-134. The proposed construction
is similar to that discussed in the previous report and will consist of a one and two story structure
over a basement level. Spread footings bearing on the natural soils designed for an allowable
bearing pressure of 2,500 psf were recommended for foundation support in our previous report.
Based on the additional information obtained from the current excavation observation, it was
recommended the footings be re-designed for an allowable bearing pressure of 2,000 psf.
At the time of our August 2 site visit, the foundation excavation which was essentially complete
had been cut in three levels from about 5 to 12 feet below the adjacent ground surface. The soils
exposed in the bottom of the excavation consisted of medium dense, silty clayey sand with
scattered gravel, cobbles and boulders. Results of swell-consolidation testing performed on
samples taken from the site, shown on Figure 1, indicate the soils are moderately compressible
under conditions of loading and wetting. The laboratory test results are summarized in Table 1.
No free water was encountered in the excavation and the soils were slightly moist to moist.
The soil conditions exposed in the excavation are not consistent with those previously
encountered on the site but should be suitable for support of spread footings designed for an
Coleman Custom Homes
August 9, 2018
Page 2
allowable allowable bearing pressure of 2,000 psf as recommended by us verbally for the re-
design. Loose and disturbed soils should be removed in the footing areas to expose the
undisturbed natural soils and the subgrade moistened and compacted. Other recommendations
presented in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous limited subsurface exploration at the site.
Variations in the subsurface conditions below the excavation could increase the risk of
foundation movement. We should be advised of any variations encountered in the excavation
conditions for possible changes to recommendations contained in this letter.
If you have any questions or need further assistance, please call our office.
Sincerely, �` 0�11 4
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David A. Young, P = 2 t�.+` ��
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attachments Figure 1 - Swell-Consolidation Test Results
Table 1 - Summary of Laboratory Test Results
cc: KRM Consultants —Ryan Schmidt (ryan@krmconsultants.com)
H-PMKUMAR
Project No. 17-7-134.01
SAMPLE OF: Silty Clayey Sand
FROM: Bottom of East—Central Portion
of Excavation
WC = 20.1 %, DD = 103 pcf
1
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
O DUE TO WETTING
J -1
W
r
I —2
• _3
J '
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(-) —4
—5
—6
These test results apply only to the
samples tested.The testing report
shall not be reproduced,except in
F. full,without the written approval of
Kumar and Associates,Inc.Swell
Consolidation testing performed in
accordance with A5154 D-4546.
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617-7-134.01 H-PvKUMAR SWELL-CONSOLIDATION TEST RESULTS Fig. 1
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