HomeMy WebLinkAboutObservation of Excavation 05.29.2025l$A $i;r*fi'ff::*$rn'i:3;'**.
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
email: kaglenwood@kumarusa.com
wurui_kumarusa.com
An Employae Owned Gompcny
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit Counly, Colorado
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Christian Harra
149 LaFrenz Circle
Silt, Colorado 81652
Miger914@hptmaiLcou
Project No. 25-7-355
Subject: Observation of Excavation, Proposed Addition to Existing Residence, 149 LaFrenz
Circle, Silt, Colorado
Dear Christian:
As requested by John Creach, a representatlve of Kumar & Associates observed the excavation
at the subject site on May 21, 2025 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation support are presented in
this report. The services were performed in accordance with our agreement for professional
engineerirgg .services to you daled May-20" 2025.
The existing residence has a basement level under it. We understand that the new footing
foundations were designed for an allowable soil bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation on the north side of the house had
M* cd ir+ are*:q#R b@+ eae+ S &4ed&d4 *he'.@ grs# *shre. Th*'sees +xpa€ed
in the bottom of the excavation consisted of sandy silty clay to graveliy sandy ciayey silt. Results
of swell-consolidation testing performed on a sample of the sandy clayey silt taken from the site,
shown on Figure 1, indicate the soils are moderately compressible under conditions of loading
and wetting. No free water was encountered in the excavation and the soils were slightly moist
tc'r,tm*G.
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 pressure of 1,500 psf should be adequate for support of the proposed addition. The
exposed soils tend to .be rnore compressible vvhen wetted and lhere could be some post-
construction settlement oflthe Tbundafion if the beadng so$s become wet. Fbcfiings should be a
minimum width of 16 inches for continuous walls and 2 feet for columns. Loose and disturbed
soils in footing areas should be removed and the bearing level extended down to the undisturbed
lratural soils. Exterior footirrgs should be provicled with adequate soil covcr ahove lheir bearing
elevations for frosi proiection= ConUnuous foundation uralls should be reinforeed to,p and bottom
to span local anomdies sueh as hy assuming sn unsupported fengft uf at least {S feet.
Foundation walls acting as retaining structures should also be designed to resist a lateral earth
pressure based on an equivalent fluid unit weight of at least 55 pcf for on-site soil as backfill. A
perimeter foundation drain should be provided to prevent temporary buildup of hydrostatic
pressrre hebird ite,basensrt wa[s €&d sr€xe{s uee$in* af ihe Iser hvel"" Strucbrd {ill placed
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page 2
within floor slab are6 can consist qf $e otF,€ite scils conrpacred to afi lerot 95% of standard
Prs.s$en#uSiry#*i?rtriisihffimsiid$wry-l*inctir?s:*- ffi@welaqd$tre*F.s#ru'*fu.16
be cornpacted and tf* serface graded to trerc-rit poncfing ufrftin at bast t$ fuefi of fte building.
The recommendatlons suUmitted in thrs letter are based on our observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
subsurface cc*S#lars uftftirx fr€ Eaff# ffi dfuexl*ibm; " YFrle ffi"l*v b based sn the
as*tm$Ht msafr * ffit re'fuotirry $ffiG ry* m hffi s*ryue {Pffi! groce eryoced- The
risk of foundation movement may be greater than indicated in this report because of possible
variations in the subsurface conditions. ln order to reveal the nature and extent of variations in
the subsurface conditions below the excavation, drilling would be required. lt is possible the data
obiained by stibsi.lrkre exff*f,sffirrt saalH *FrafiF tE* rees€E*lrendatft*ns €cffirtaiined in thi* lefier.
ftrr sen*ilJes do r# *srctttde dffiwua*tq Ete frwtrne, pra{Hr[ion u pcssffiy oif ffistrd or otrtgr
biologicalcontaminants (MOBC) developing in the future. lf the client is concerned about MOBC,
then a professional in this specialfield of practice should be consulted.
lf you have any questions or need further assistane" please call our office-
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Daniel E, Hardin, P.E"
Rev. by: SLP
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