HomeMy WebLinkAboutObservation of Excavation 05.05.17H-PryKUMAR 5020 County Road 154
Glenwood Springs, C0 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Geotechnical Ëngineering I Engineering Geology
Materials Testing I Environmental
Office Locations: Parker, Glenwood Springs, and Silverthorne, Colorado
l;Nf.ay 5,2017
James Martinez & Ashley Church
1055 County Road 255
Rifle, Colorado 81650
¿rcashle]¡marie @ gmail.com
Project No. 17-7-219.01
Subject:Observation of Excavation, Proposed Residence, Lot 33, Sun Meadow Estates,
South Meadow Drive, Garfield County, Colorado
Dear James Martinez & Ashley Church:
As reqnested, a representative of H-P/Kumar observed the excavation at the subject site on April
24,2017 to evaluate the soils exposed for foundation support. The findings of our observations
and recommendations for the foundation design are presented in this report. V/e previously
conduoted a subsoil study for design of foundations at the site and presentecl our findings in a
report dated April4,2016, Job No. I7-1-219.
The proposed constrnction is two-story wood frame structure over crawlspace and an attached
gurag", similar to that discussed in onr previous report. 'We ttnderstand the building location has
been moved about 15 to 20 feet from the location showtt in otlr subsoil study report. The
structure will be founclecl on spread footings designed for a maximum soil bearing pressure of
1,500 psf with some risk of movement'
At the time of our visit to the site, the foundation excavation had been cut iu 2 levels. The main
level had been cut from2Vzto 4Vz feet below the adjacent ground surface and an Llpper area in
the northwest corner ofthe excavation had been cut from I to lvz feet below adjacent grade. The
excavation was about 90Va complete at the time of ottr observation. The soils exposed in the
bottom of the excavation consisted of stiff, sandy silty clay. There was some loose material in
areas of the excavation that were recommended be moistened and compacted prior to the
placçment of concrete. Results of swell-consolidation testing performed on a sample taken fi'om
the site, shown on Figure 1, indicate the soils are moderately compressive and possess a
moderate collapse potential under conditions of loading and wetting. The sample was likely
distur.bed from the sampling process. No free water was encountered in the excavation and the
soils were slightly moist to moist.
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 pressllre of 1,500 psf. The risk of foundation movement is primarily if the bearing soils
were to become wetted and precautions should be taken to prevent wetting. Loose and disturbed
soils should be removed in the footing areas to expose the undisturbed natural soils and the
James Martinez
May 5,2017
Page 2
subgrade compacted. The bearing soils should be protected from frost and concrete should not
be placed on frozen soils. Other recommendations presentecl 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 incrcase 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. Our services do not include
determining the presence, prevention or possibility of mold or other biological contaminants
(MOBC) developing in the future. If the client is concerned about MOBC, then a professional in
this special field of practice should be consulted.
If you have any questions or need further assistance, please call our office
Sincerely,
H.P* KUMAR
'Erfc"^l- Ðu't*',@
Robert L. Duran, E. I.
Reviewed by
David A. Young, P.E
RLD/ksw
Attachments: Figure I - S on Test Results
H-P\KUMAR
Project No. 1 7-7-21 9.01
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