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Geoteún¡câl and Maføials Engheers
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June 10,2019
Mark Sage
1181 East 19ú Street
Rifle Colorado 81650
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Project No. I 7-7-282.01
Subject:Observation of Excavation, Proposed Shop Building, Tract C5, Scutter Gulch
Subdivision, 1181 County Road 259, Garfield County, Colorado
Dear Mark:
As requested by Joe Rando, a representative of Kumar & Associates observed the excavation at
the subject site on Mlay 7,2019 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations are presented in this report. The services a¡e
supplemental to H-P/I(umar (now Kumar & Associates) agreernent forprofessional services to
you dated April 4,2017.
H-P/I(umar previously conducted a subsoil study for design of foundations at the site and
presented our findings in a report dated May 26,2A17, Project No. 17-7-282. The proposed
construction is similar to that discussed in that report. Spread footings sized for an allowable
bearing soil pressure of 2,500 psf bearing on a minimum 3 feet of compacted structural fill were
designed for foundation support of the building based on recommendations provided in the
previous report, with some risk of movement. Only the shop building is being built at this time.
At the time of our site visit, the foundation excavation for the shop building was essentially
complete and consisted of 1 I isolated footing pads each cut at one level from about lYz to ZYz
feet below tþe adjacent ground surface. The soils exposed in the bottom ofthe excavations
consisted of about 3 feet of minus 3/e-inch aggregate base course placed as the structural fill in the
footing pad areas. Compaction testing on the surface of the structural fill indicated the base
course was compacted to from about 97 ta 1,00% standard Proctor density assurning a maximum
standard Proctor value of 130 pcf at 6.5% optimum moisture content. Results of swell-
consolidation testingperformed on a sample of the siity clay taken from the site, shown on
Figure I, indicate the shallow soils are moderately compressible under conditions of loading and
wetting. No free water was encountered in the excavation and the silty clay soils were generaliy
moist and the skucfural fill soils sligbtly moist.
The soil conditions exposed in the excavation are generally consistent with those previously
encountered on the site and the structural fill compacted as generally recommended, and suitable
for support of spread footings designed for the design allowable bearing pressurc of 2,500 psf.
Mark Sage
June 10,2019
Page2
The risk of foundation movement is if the bearing soils below the structtral fill were to become
wetted and precautions should be taken to prev€,nt wetting. Prior to the footing construction, all
loose disturbed soils should be rernoved and the shrctural fill moistened and re-compacted as
needed. Other recommendations presented in our previous report which are applicable should
also be observed.
The recomme,ndations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation, the limited compaction testing on the structural fill, and the
previous zubsurface exploration at the site. Variations in the subsr¡rface conditions below the
excavation could increase the risk of foundation movement. We should be advised of any
va¡iations 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 ofiñce.
Sincerely,
Idü¡eïar &
David A. Young,
DAY/kac
attachment Figure 1 Test Results
cc: Rando Construction - Joe Rando (lj¡j!5.U:,i1.:¡¡..!ti-i,ì.,.¡)
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SAMPLE OF: Sondy Silty Cloy
FROM: Botlom of Norlhwesl Portion of
Excovollon
IVC = 14.6 %, Dt = 102 pcf
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ADDITIONAL COMPRESS¡ON
UNDER CONSTANT PRESSURE
DUE TO WETT]NG
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17-7-282.01 H-PTKUIVIAR SWELL-CONSOLIDATION TEST RESULTS Fig. 1