HomeMy WebLinkAboutObservation of Excavation 04.13.2017H-PKUMAR
Geotechnical Engineering 1 Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
April 13, 2017
Stephen Self
1098 County Road 214
Silt, Colorado 81652
Stephen l lowwisp.net
Office Locations: Parker, Glenwood Springs, and Summit County, Colorado
Project No. 17-7-288
Subject: Observation of Excavation, Proposed Detached Garage, 1098 County Road 214,
north of Silt, Garfield County, Colorado
Dear Stephen:
As requested, a representative of H-P/Kumar observed the excavation at the subject site on April
5, 2017 to evaluate the soils exposed for foundation support. The findings of our observations
and recommendations are presented in this report. The services are supplemental to Hepworth-
Pawlak Geotechnical's (now H-P/Kumar) agreement for professional services to you dated April
29, 2016.
Hepworth-Pawlak Geotechnical previously observed a backhoe pit at the site for design of the
garage foundation and presented the findings in a report dated May 20, 2016, Job No. 116 154.
The proposed construction is similar to that discussed in the previous report. Spread footings
designed for an allowable soil bearing pressure of 1,500 psf were recommended for foundation
support with some risk of settlement.
At the time of our site visit, the foundation excavation which was essentially complete had been
cut in one level from about 31/2 to 4 feet below the adjacent ground surface. The cut depth in the
garage floor slab area was about' to 1 foot deep. The soils exposed in the bottom of the
foundation excavation consisted of generally stiff, sandy clay and silt. The excavation subgrade
had been compacted. In the northeast corner of the excavation was some standing water and a
few inches pf muddied subgrade soils reportedly from a leaking garden hose. Results of swell -
consolidation testing performed on samples taken from the site, shown on Figure 1, indicate the
soils are slightly to moderately compressible under conditions of loading and wetting. No free
water was encountered in the excavation and the soils were generally moist in the non -wetted
areas.
The soil conditions exposed in the excavation are consistent with those previously encountered
on the site and suitable for support of spread footings designed for the recommended allowable
bearing pressure of 1,500 psf. Loose or disturbed and any muddied soils should be removed in
the footing areas to expose the undisturbed natural soils, and the subgrade re -compacted as
Stephen Self
April 13, 2017
Page 2
needed. 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,
H -Pt, KU • R
David A. Young, P, 'Di i 5
1
DAY/ksw
"4 N•e°f„:rannool�
attachments Figure 1, Swell-'onsolidation Test Results
cc: Garfield County Building Dept. — Jim Wilson jwilson@garfield-county.cotn)
H-Pk-KUMAR
Project Nio. 17-7-288