HomeMy WebLinkAboutObservation of excavation ReportI(tA Im&lssoclailes,hG."
Geotechnical and Materials Engineen
ard Environrenlal Scientists
An Emdoycc Outncd Conpony
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax (970) 94s-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com
Office l-ocatiom: Denver (HQ), Parker, Colorado Springs, Fort Colinq Glenwood Springs, and Summit County, Colorado
May 20,2024
Linda Hansen
3290 County Road 210
Rifle, Colorado 81650
lhansen@sopris.net
Project No.23-7-675
Subject:Observation of Excavation, Proposed Garage and Accessory Dwelling Unit
(ADU), 3290 County Road 210, Garfield County, Colorado
Dear Linda:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on May 9, 2024 to evaluate the soils exposed for foundation support. The findings of
our observations and recommendations for the foundation design are presented in this report.
These services were perfbrmed as supplemental to our agreement for geotechnical engineering
services to you dated November 30,2023. We previously conducted a subsoil study for design
of foundations at the site and presented our findings in a report dated January 15,2024, Project
No.23-7-675.
The proposed garage and ADU will be a two-story structure with the garage on the ground floor
and the ADU on the second level. The building has been designed to be supported on spread
footings sized for an allowable bearing pressure of 1,500 psf with a risk of settlement primarily if
the bearing soils become wetted.
At the time of our visit to the site, the foundation excavation had been cut in one levelfrom2t/z
to 3 feet below the adjacent ground surface. The soils exposed in the bottom ofthe excavation
consisted of silty sand. Results of swell-consolidation testing performed on a sample taken from
the site, shown on Figure 1, indicate the soils are compressible under conditions of loading and
wetting. No free water was encountered in the excavation and the soils were slightly moist to
moist.
CIP0"t trMt e
LlnrdaHansen
May 19,2024
Page2
The soil conditions exposed in the excavation are consistent with those encountened
on the site and suitable for sup'port of spread footinp designed for the recommeirded allowable
bearing pressure of 1,5@ psf with a risk of settleme,nt. l,oose distrnbed soils should be
moistened to near optimrm and compacted. Other recommendations presented in our pnevious
report which are applicablq especially those to keep thebearing soils dry, should also be
observod.
The recommendations submittd in this letter are based on our obserrration of the soils exposed
within the foundation excavalion 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 encounterod in the excavation onditions for
possible change to recommendations contained in this letter. Our services do not include
determining the prese,nce, prwention or possibility of mold or otherbiological contaminants
(MOBC) developing in the future. If the client is concerned about MOBC, then aprofessional in
this special field ofpractice shouldbe consulted.
If you have any questions or nd further assistance, please call our office.
Sincerely,
Kumar & Associates, lnc.
James H. Parsonso P.E.
Rw. by: SLP
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attachments Figure I - Swell-Consolidation Test Results
J-Caliber Construction - Jose Gonzalez- jose@icaliberconstruction.comeci
Kumar & Associates, lnc. @ Project No.23-7-675
!
I
SAMPLE OF: Silty Sond
FROM: Northwest Corner ol Footing Grode
WC = 9.0 X, DD = ,l10 pcf
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ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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23-7-67s Kumar & Associates SWELL_CONSOLIDATION TEST RESULTS Fig. 1