HomeMy WebLinkAboutObservation of Excavation 03.19.24l(t,t lfitmr * A$qrsiats, ln*,s
Ge+technical and Materials Engineers 5020 County Road 154
and Cnvir*nmental$cientists Glenwood Springs, CO 81601
phone. (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
An fmplorycc onfr$ss coilpEny www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
March 19,2A24
James Gornick Building Specialists
Attn: James Gornick
1005 Cooper Avenue
Glenwood Springs, CO 81601
Jeornick I 9 8 8 @,smail. com
Subject:
Project No.24-7-194
Observation of Excavation, Proposed Addition, Lot 8, Rapids on the Colorado,
l8l Rapids View Lane, New Castle, Colorado
Gentlemen:
As requested, a representative of I(umar & Associates observed the excavation at the subject site
on March 13,2024 to evaluate the soils exposed for foundation support. The findings of our
obseryations and recommendations for the foundation support are presented in this report. The
services were performed in accordance with our agreement for professional engineering services
to James Gornick Building Specialists dated March 12,2024.
We understand that the proposed addition has been designed to be founded on spread footings
bearing on the natural soils sized for an allowable bearing pressure of 1,000 psf assumed by the
structural engineer.
At the time of our visit to the site, the foundation excavation had been cut in one level from 2 to
2% feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of very sandy silty clay. Results of swell-consolidation testing performed on samples
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 moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an allowable
soil bearing prcssure of 1,000 psf can be used for support of the proposed addition. The exposed
soils tend to compress when wetted and there could be some post-construction settlement of the
foundation that could be differential to the existing residence, especially if the bearing soils
become wet. Footings should be a minimum width of l8 inches for continuous walls and,2 feet
for columns. Loose and disturbed soils in footing areas should be removed and the bearing level
extended down to the undisturbed natural soils. Exterior footings should be provided with
adequate soil cover above their bearing elevations for frost protection. Continuous foundation
walls should be reinforced top and bottom to span local anomalies such as by assuming an
unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also
be designed to resist alateral earth pressure based on an equivalent fluid unit weight of at least
55 pcf for on-site soil as backfill. Structural fill placed within floor slab areas can consist of the
on-site soils compacted to at least 95Y" of standard Proctor density at a moisture content near
James Gomick Building Specialists
March 19,2424
Page 2
optimum. Backfill placed around the structure should be compacted and the surface graded to
prevent ponding within at least l0 feet of the building. Landscape that requires regular heavy
irrigation, such as sod, and sprinkler heads should not be located within l0 feet of the
foundation.
The recornmendations submitted in this letter are based on oilr observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
subsurface conditions within the loaded depth of foundation influense. This study is based on
the assumption that soils beneath the footings have equal or better support than those exposed.
The risk of foundation movement may be greater than indicated in this report because ofpossible
variations in the subsurface conditions. In order to reveal the nature and oxtmt of variations in
the subsurface conditions below the excavation, drilling would be required. It is possible the
data obtained by subsurface exploration could change the recommendations contained in this
letter. Our services do not include determining the presence, prevention or possibility ofmold or
otherbiological contaminants (MOBC) developing in the firture. If the client is concerned about
MOBC, then a professional in this special field of practice should be consulted.
If you have any questions or aeed further assistance, please call our office.
Sincerely,
${uxn*x*" &: Ass**N*$*s*
Robert L. Duran, P.E.
Rev. by: DEH
RLD,{<ac
Attachment:Figure I - Swell-Consolidation Test Results
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Kumcr & A*so.*lates, $m6" tr Pr*Jrct ffis. ***?-tSd
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SAMPLE OFr Very Sondy Sllty Cloy
FROM: North Eosl Corner of Boitom of Excovolion
WC = 16.7 %, DD = 106 pcf, -2OO = 52 %
NO MOVEMENT UPON
WETTING
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Bompl@ t8t d. Tho t..ting r.port
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full. *ithoul th. vdtton dpprovol of
Kumor ond Aaaociot€, lnc. Swall
Conelidotion t6tin€ p.rform.d in
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24-7 -194 Kumar & Associates SWTLL_CONSOLIDATION TTST RESULTS Fig. 1