HomeMy WebLinkAboutObservation of ExcavationI(t'T l(unnr & Assoclatss, lnc.'
Geotechnical and Materials Engineers
and Environmental Scientists
An Emdoycc Orncd Conrpony
5020 Cormty Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
www.kumanrsa.com
Office t ocetions: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit C$nty, Colorado
December 30,2A24
Garret Construction
Attn: Steven Fotion
131 Meadow Court
Carbondale, Colorado 81623
stevenfotion@yahoo. com
Project No.24-7-704
Subject: Observation of Excavation, Proposed Pergola Addition, Lot 16, Teller Springs,
0037 Spur Drive, Garfield County, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on December 18,2024 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation design are presented in
this report. The observation was performed in accordance with our agreement for professional
services with Garret Construction dated December 17,2024.
The proposed pergola is located above an existing concrete patio slab and designed to be
supported on four 36-inch diameter Bigfoot piers sized for an allowable bearing pressure of
2,000 psf.
At the time of our visit to the site, three of the pier excavations were complete and each cut in
one level from about 3 to 5 feet below the adjacent ground surface. The soils exposed in the
bottom of the excavations consisted of stiff to very stiff sandy silty clay. The fourth, southeast
pier excavation was in progress and appeared to have exposed the clay soil. Results of swell-
consolidation testing performed on a sample of the clay taken from the site, shown on Figure 1,
indicate the soils have low to moderate compressibility under conditions of loading and wetting.
The laboratory test results are summarizedin Table 1. No free water was encountered in the
excavations and the soils were slightly moist to moist.
The clay soils exposed in the excavation are consistent with those expected to be encountered on
the site and can be used for support of pier footings designed for the assumed allowable bearing
pressure of 2,000 psf with a settlement risk. The soils tend to compress under load when wetted
and precautions should be taken to keep the bearing soils dry by proper backfill placement and
compaction. Loose disturbed soils should be removed in the footing areas to expose the
undisturbed natural soils. The bearing soils should be protected from frost and concrete should
not be placed on frozen soils. Backfill around the piers can consist of the onsite soils compacted
to at least 90olo of standard Proctor density with a positive slope to drain away from the piers and
patio slab.
Garret Construction
Dece,nrber 30,2024
Page2
The recommendations submitted in this letter me based on our observation of the soils exposed
within the foundation excavation and do no include subsurface exploration at the site. Variations
in the subsurface conditions below the excavation could increase the risk of foundation
movernent. We 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 & Aasociates,
Steven L. Pawlak,
SLP/kac
Attachments: Figure I Test Results
Table 1 - Summary of Laboratory Test Results
Kumar & Associates, lnc. t Prcject No.2S7-704
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TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Projec't ],b.2+7-704
Southwest Comer
Northeast Corner
BOTTOil OFB(CAVATION
SATIPLE LOCATION
15.3
20.2
NATUML
TNOSTURE
COTIIENT
NATURAL
DRY
DENSITY
86
97
GRAVEL
(%)
GMDATION
sAl,tD
(%)
93
PERCENT
PASSIilG l,to.
2mstEl/E
LKIUID LMN
t%l
ATIERBERG LITITS
PLASTIC
INDE(
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UNCONFINED
COTilPRESSIIE
STRENGTI{
{PSR
Silty Clay
Sandy Silty Clay
sotLoR
BEDROCKTYPE