HomeMy WebLinkAboutObservation of Excavation 07.10.2023lGrtffi'*"
An Bîßloycc Ourmd Conrpony
5020 County Road 154
Glenwood Springs, CO 8ló01
phone: (970)945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
www.kumarusacom
Offrce Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
July 10,2023
Robert Leavitt
P.O. Box 4441
Basalt, Colorado 81621
crimsonconstructioninc@ gmail.cou0
Project No. 22-7-400
Subject: Observation of Excavation, Proposed Residence, Lot 31, Mountain Springs
Ranch, Saddleback Road, Garñeld County, Colorado
Dear Mr. Leavitt:
As requested, a representative of Kumar & Associates, Inc. observed the excavation and tested
compaction of structural fill being placed at the subject site on July 6, 2023 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 conducted a subsoil study for
design of foundations at the site and presented our findings in a report dated JuIy 27 ,2022,
Project No.22-7-400.
At the time of our visit to the site on June 27,2023, the foundation excavation had been cut in
three levels from 3 to 6 feet below the adjacent ground surface. The soils exposed in thebottom
of the excavation consisted of medium dense gravel with scattered cobbles in a sandy clay matrix
and very stiff slightly sandy clay with scattered gravel.
'We recommended that the clay soils be removed down to gravel and cobble soils or a depth of
2 feet below foundation bearing elevation and footing grade re-established with structural fill
consisting of % incb aggregate base course.
At the time of our visit to the site on July 6,2023, the foundation had been cut in multþle levels
fuom6Yz to 11 feet below the adjacent ground surface ands/a-inch aggregate base course was
being placed to re-establish foundation bearing elevation. No free water was encountered in the
excavation and the soils were slightly moist to moist. Nuclear density testing results performed
at 5 locations on various lifts of the t/a-inchaggregate base course indicated compaction of 100%
to 101 .7Yo of the standard Proctor density at a moisture content within 1 percent of optimum
moisture contsnt.
The soil conditions exposed in the excavation are consistent with those previously encountered
on the site and the structural fill is suitable for support of spread footings designed for the
recofitmended allowable bearing pressure of 2,000 psf. Loose and disturbed soils should be
removed in the footing areas to expose the undisturbed natural soils. Other recommendations
presented in our previous report which are applicable should elso 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
Robert Leavitt
July 10,2023
Page2
in the subsurface conditions below the excavation could increase the risk of foundation
movement. W'e 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
detennining the presence, prevention or possibility of mold or other biological contaminants
(MOBC) developing in the future. If the client is concerned about MOBC, then aprofessional in
this special field of practice should be consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar &
Robert L. Duran,
Rev. by: DEH
RLDlkac
Kumar & Associates, lnc. o Project No.22-7-400