HomeMy WebLinkAboutObservation of Excavation 05.22.2019lGrtffi[ffiffil#ü'*"
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an Employoc Otrnocl Compony
.5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
ernai I : kaglenwood@;kurnarusa.corn
www.kumarusa.cojr
OffÌce Locations: Denver (HQ), Parker, Cc¡loraclo Springs, Forl Collins, Glenrvood Sprìngs, and Su¡n¡nit County; Colorado
l|lf.ay 22,2019
Esau Ruiz
P. O. Box 450
Silt, Colorado 81655
esaurui¿;9Q(i¿1¡¡4!1. com
Subject
Project No. l9-7-1 1 9.01
Observation of Excavation, Proposed Residence, Dixon Foundation Water Parcel
2179-114-00-733, County Road 346, south of Silt, Garfield County, Colorado
Dear Esau:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on May 3 , 2019 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 25,2019.
We previously conducted a subsoil shrdy for design of foundations at the site and presented our
findings in a report dated March 14,2019, Project No. 19-7-119. The proposed construction is
similar to that discussed in that report. The building has been designed to be supported with
spread footings bearing on the natural soils sized for an allowable bearing pressure of 1,500 psf
with a risk of settlement, based on the recommendations provided in the previous report.
At the time of our site visit, the foundation excavation which was essentially complete except for
the attached garage area had been cut in one level from about I to 2Yz feet below the adjacent
ground surface. The soils exposed in the bottom of the excavation consisted of medium dense,
silty to very silty and clayey sand. A backhoe pit dug to footing elevation at the southwest
comer of the garage area indicated similar sand soils at footing bearing elevation. Results of
swell-consolidation testing performed on samples taken from the site, shown on Figure 1,
indicate the soils are moderately to higþly compressible under conditions of loading and wetting
with a moderate hydro-compression potential. The sample may have been partly disturbed due
to the sampling process. No free water was encountered in the excavation and the soils were
slightly 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 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. Providing 3 feet of structural
fìll below the footings as discussed in our previous report would act to reduce the risk of
settlement. Prior to the footing construction, all loose disturbed soils should be removed to
Esau Ruiz
N4ay 22,2019
Page2
expose the undisturbed natural soils, and the subgrade moistened and compacted. 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. V/e 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,
Kumar &
/1
David A. Young, P
,t
DAY/hac
attachment Figure 1,Test Results
Kumar & Associates, lnc. ri Project No. l9-7-119.01
I
SAMPLE OF: Very Silty Sond
FROM: Bottom of Excovotion
WC = 6.0 74, DD = 101 pcf
2 I i tl
)
0
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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zo
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1 n
-12
1,0 10 100
19-7- 119,01 Kumar & Associates SWELL_CONSOLIDATION TtST RISULT Fig. 1