HomeMy WebLinkAboutObservation of Excavation 07.24.2018PKUMAR
Geotechnical Engineering I 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
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
July 24, 2018
Todd Bryan
45 Oak Court
Parachute, Colorado 81635
Todd. bryan66 C gniai l.com
Project No. 18-7-112.01
Subject: Observation of Excavation, Proposed Residence, Lot 12, Monument Ridge,
100 Dry Creek Road 331, Battlement Mesa, Garfield County, Colorado
Dear Todd:
As requested by Rex Smith, a representative of H-P/Kumar observed the excavation at the
subject site on July 3, 2018 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 our agreement for professional services to you dated January 16, 2018.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated February 6, 2018, Project No. 18-7-112. The proposed construction is
similar to that discussed in the previous report. Spread footings bearing on the natural soils
designed for an allowable bearing pressure of 1,500 psf were recommended for foundation
support, with some risk of movement.
At the time of our site visit, the foundation excavation had been cut in one level from about 2 to
51/2 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of stiff, sandy clay and silt. The excavation subgrade had been moistened and
compacted. Results of swell -consolidation testing performed on a sample taken from the site,
shown on Figure 1, indicate the soils are moderately to highly compressible under conditions of
loading and wetting with a moderate collapse potential when wetted under a constant 1,000 psf
surcharge. The sample was likely partly disturbed during the sampling process, however, the
near surface soils in the area of the subject site typically do have a hydro -compression potential.
No free water was encountered in the excavation and the soils were slightly moist.
The soil conditions exposed in the excavation are generally 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. The risk of settlement is primarily if the
bearing soils were to become wetted and precautions should be taken to prevent wetting. Prior to
Todd Bryan
July 24, 2018
Page 2
the footing construction, all loose disturbed soils should be removed and the subgrade re -
compacted as 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 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 -P KU MAR
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Robert L. Duran, E. I.
Reviewed by
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attachments Figure 1 — Swell-tonsolidation Test Results
cc Cornerstone Builders — Rex Smith (rex.smith7@aol.com)
Garfield County Building Dept. — Jim Wilson (iwilson@garfetd-couiity.com)
Project No. 18-7-112.01