HomeMy WebLinkAboutObservation of Excavation 08.17.22l$rtflå#l[*iffßHi,r'3ü*.*5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumanrsa.com
www.kumantsa.comAn Employsc Owncd Compony
Office Locations: Denver (HQ), Parkeq Colorado Splings, Fort Clollins, Glenrvood Springs, and Sumnrit County, Cololado
September 16,2022
Surprise Valley l,LLC
Attn: Jimmy Terui
5444 Cot:nty Road226
New Castle, Colorado 81647
it@)tebuilders.net
Project No. 21-7-925.4
Subject: Observation of Excavation, Proposed Residence, Lot2l-A, Grand Hogback
Exemption, 2452 County Pioad 237, Gar{ield County, Colorado
Jimmy:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on September 13,2022 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation design are presented in this
report. We previously conducted a subsoil study for design of foundations at the site and
presented our findings in a report dated February 1,2022, Project No.2l-7-925.
The proposed residence is essentially the same as described in our previous report and will be
slab-on-grade floor with spread footings sized for an allowable bearing pressure of 2,000 psf.
At the time of our visit to the site, the foundation trench excavations had been cut in one level
from 3 to 4 feet below the adjacent ground surface. The soils exposed in the bottom of the
excavation consisted of sandy clay and clayey sand with gravel. Results of swell-consolidation
testing performed on a sample taken from the site, shown on Figure l, indicate the soils have low
compressibility under light loading and moderate compressibility under additional loading after
wetting. The laboratory test results are suilrmarized in Table 1. No free water was encountered
in the excavation and the soils were slightly moist to moist.
The soil conditions exposed in the excavation are similar to those previously encountered on the
site but appear more variable with less clay and expansion potential than expected. We
recommend that spread footings be placed on at least lt/z feet of road base structural fill and
designed for the recommended allowable bearing pressure of 2,000 psf to lessen the variability
and movement potential. The structural fill should extend at least one foot beyond the footing
edges and be compacted to at least 98% of standard Proctor density at near optimum moisture
content. The exterior deck piers should not need structural fill for bearing unless they carry roof
loading. Loose disturbed soils in the footing areas should be moistened and compacted prior to
placing structural fill or concrete. Other recommendations presented in our previous repoft
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 subsurface exploration at the site. Variations
Surprise Valley I,LLC
September 16,2022
Page2
in the subsurface conditions below the excavation could increase the risk of foundation
movement. We 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
determining the presence, prevention or possibility of mold or other biological contaminants
(MOBC) developing in the future. 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 need further assistance, please call our office.
Sincerely,
Kumar & Associates,
Steven L. Pawlak, P
SLP/kac
Attachments: Figure 1-Test Results
Table 1 - Summary of Laboratory Test Results
cc: JimRomeo0in@iirctgzu'al,cqpl)
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Kumar & Associates, lnc. o Project No.21-7-925.4
SAMPLE OF: Sondy Cloy
FROMr Norlheosl Corner
WC = 't 2.7 %, DD = 93 pcf
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ADDITIONAL COMPRESSION
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Fig. 1Kumar & Associates SWELL-CONSOLIDATION TESÏ RESULTS21 -7 -925A
lC irffi?:ffifffinr'ifú-*TABLE 1SUMMARY OF LABORATORY TEST RESULTSNo.2l-7sotloRBEDROCKTYPESandy ClayCþey SandIPSRUNCOT{FINEDcorPREssrvESTRENGTHPLASNCINDEXfY"ìATTERBERG LIMffSl'/"1LK¡Uþ I.IMIÍPERCENÍPASSING NO.2m sEvE35l%'tSA}¡DGRAOATION(%)GRAìÆL939412.720.tBOTTOT OF EXCAVATIONLOCANONNATURALDRYDENSFYNATURALMOFTURECONTENTNortheast CornerSouthwest Corner