HomeMy WebLinkAboutObservation of Excavation 05.05.17H-PryKUMAR
Gootechnicel Engineering I Engineering Geology
Materlals Testing I Environmental
5020 County Road 154
Glenwood Springs, C0 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Parkcr, Glenwood Springs, and Silverthorne, Colorado
N'4ay 5,2A17
James Martinez & AshleY Church
1055 County Road 255
Rifle, Colorado 81650
açash leynrade @ grtlir¡ l.cont
Project No. l7-7-2 I 9.01
Subject:Observation of Excavation, Proposed Residence, Lot 33, Sun Meadow Estates'
South Meadow Dlive, Garfield County, Colorado
Dear James Martinez & Ashley Church:
As rcquested, a representative of H-p/Kumar observecl the excavation at tlre sulrject ;ite on April
24, z0l7 to evaluate the soils exposed for foundation support, The findings of ottr olrservations
and recommendations for the foirndation design are presented in this l'epoil' We pleviously
conducted a subsoil stucly for design of foundations at the site and preseutecl our findings in a
r€port clated April 4,2016, Job No. l7-7-219'
The proposed construction is two-stofy wood frarne structure over crawlspace and an attached
guru!", ,i-ilu, to that discussed in our previous report. we understand the building location has
t."rfrnon"d about 15 to 20 feet from the location shown in our subsoil study report. The
strLìctue will be f-ogncled on sprcad footings designed for a maximum soil bealing 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 in 2 tevels. The rnain
level had been cnt fron2rhto vzfeet bclow the acljacent ground surface and an Llppef arca in
the northwest corncr ofthe excavation had been cut from I to |Y2feet below adjacent grade. The
excav¿ition was about 90Va complete at the time of our observation. The soils exposecl in the
bottom of the excavation consisied 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-consslidation testing perl'oilned on a saniple taken fi'om
ihe site, shown on Figure 1, indicate the soils are moclerately compressive and possess a
moderate collapse piential under conditions of loading and wetting. The sartrple was likely
distu'bed from the sampling process. No fiee water was encountered in the excavation and the
soils were slightly moist to moist.
The soil conditions exposecl in the excavation are consistent with those previously encountered
on the sire and suitablË for suppolt of spread footings designed for the recommended allowable
bearing ple¡i.,ure of 1,500 prr. bne risk of foundation rilc¡vement is prinarily if the bealing soils
wer.e to become wetted anä precautions should be taken to prevent wetting. Loose and disturbed
soils shor¡ld be removed in the footing areas to expo¡ie the undistu:bed natural soils and the
James Martinez
lllay 5, 2Ol7
Page 2
srrbgrar.lc co'rpactetl. The bearing soils should bc protcctcd fi'om frost artel cüllülete should not
6e p-laced nn Êurr¡ soils. Other recommcndations presented in our prcviotrs leport 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 advisecl of any variations encountered in the excavation conditions for
possible changes to rccomrnendations containsd in this letter. Our services do not include
ãetermining tlìe presence, plevention or pÕs$itlility of moldor othcr biological contaminants
iUôncl dãvetoping in thé furLlre. If the client is concerned about MOBC, then a professional in
ihis special field of practice should be consulted'
If you have any questions or need further assistance, please call our office'
Sincerely,
H-P* KUMAR
"ß,f'.,ù{- þuæ''@
Robert L. Duran, E. I.
Reviewed by:
David A. Young, P.E
RLD/ksw
Attachments: Figure I - S ation Test Results
H-P\KUMAR Project No. 1 7-7-21 9.01
Moisture Content : l0 I persent
Dry Density : 92 Pcf
Sarnple of: SarrtJy Silty Clay (Sligtrtly Calcateous)
From: Bottom of Middle Portiort of Excavation
ï
)
Compression
upon
'wetting
/z 7
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ì
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10
APPLIED PRESSURE - ksf
10
t¿
11
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ès
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4
5
2
3
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Figure 1SWELL-CONSOLIDATION TEST RESU LTSNRKUMAPHttê)l¡!Jy17-7 -219.01