HomeMy WebLinkAboutObservation of Excavation 05.02.24ilt*tt Kiimar & ilsscclates. Inc.
,Seoleti:rical ard l'laieiiais Enii:retts 5020 Coutrty Road 154
,tirrl Eiii,,riprnariia! Streni;sls GienwOod SpringS, CO 81601
phone. (970) 945 79BB
faxr (970) 945-8454
enrail. kaglenwood@xunrarusa. cotn
i'rr fnri:i*yee Owtre* f*n.!pat:y \':': ':' :'i:it::: ':::ir: irir:
*tfice Locatiorrs: Det-rver {HQ). Parker. Colciado Springs, Fcrl Coilins. Gieirr,vood Springs. attd Sutritrtil Cotttify. Coloiado
May 2"2024
Kevin Wakefield
7303 County Road 233
Silt. Colorado 81652
Project No.24-7-266
Subject; Observation of Excavation, Proposed Garage, 7303 County Road 233, Garfield
Count-v, Colorado
Dear Mr. Wakefield:
As requested, a representative of Kumar & Associates observed the excavation at the subject
srte on April 25, 2024 to evaluate the soils exposed for foundation sr.rpport. The firrdings of our
observations and recommendations tbr the tbundation support are presented in this report. The
services were performed in accordance with our agreement for prof'essional engineeritrg services
to you dated April 24,2024.
The proposed construction will be a 30 fbet by 30 t'eet single-story steel-tianred structure with a
slab-on-grade floor. Fourndations consist of a thickened edge designed fbr an allowable soil
bearing pressure of 1,500 psf.
At the time of our visit to the site, the fbundation excavation lrad been cut in one level abor-rt % tcr
lZzfeet below the adjacent ground surf'ace. The soils exposed in the bottom of the excavation
consisted of stiff, sandy silty clay. Results of swell-consolidation testirrg performed on samples
taken fiorn the site, shown on Figures I and 2, rndicate the soils are compressible under
conditions of loading and wetting. No free water was encountered in the excavation and the soils
were slightly rnoist to moist.
Considering the conditions exposed in the excavation and tlre rrature o1'the proposed
construction, spread fbotings placed on the r"rndisturbed natural soil designed tbr an allowable
soil bearing pressLlre of 1,500 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 if the bearing soils become wet. Footings shourld be a rninimum width of l6 inches
tbr continuous walls and 2 f-eet fbr columns. Loose and disturbed soils irr fboting areas should be
removed and the bearing level extended down to the undistr"rrbed natural soils. Exterior tbotings
shor"rld be provrded with adequate soil cover above their bearing elevations fbr fiost protectiott.
Structural fill p laced within f]oor slab areas can consist of the on-site soils to at ieast
95% ofstandard Orsture content near optimum. Backfill placed around the
be compacted and the surfbce
of the building.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the fbundation excavation and do rrot include subsurfbce exploration to evaluate the
Kevin Wakefield
May2,2O24
Page2
subsurface conditions within the loaded depth of foundation influence. 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 of possible
variations in the subsurface conditions. In order to reveal the nature and extent 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 detennining the presence, prevention or possibility of mold or
other biological contaminants (MOBC) developing in the future. If the client is concemed about
MOBC, then a professional in this special field of practice should be consulted.
lf you have any questions or need further assistance, please call our office.
Sincereiy,
-: .;," i.
/.
Shane M. Mello, Staff Engineer
Reviewed by:
Robert L. Duran,
SMMlkac
attachments Figures I l-Consol idation Test Results
.';..'i3.,ri
l_a .
E
d
SAMPLE OF: Sondy Sill ond Cloy
FROMI Bottom of Excovoiion ol Soulheost Corner
WC = 12.8 %, DD = 96 pcf
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
h
in
ff
?
)JLI
=o
I
zo
F
o
Io
@zo()
0
-2
-4
-6
-10
t.0 - KSF t0
24-7 -266 Kumar & Associates SWELL_CONSOLIDATION TEST RTSULTS Fig. 1
;
SAMPLE OF: Sondy Silt ond CIcy
FROM: Bottom of Excovolion ol Northwesl Corner
WC = '14.3 %, DD = ,l05 pcf
NO MOVEMENT UPON
WETTING
1
0
I
J -lLd
=o
t-2
zotr
o_a
Joozo<J-4
PRESSURE - KSF IO
24-7 -266 Kumar & Associates SWELL-CONSOLIDATION TIST RTSULTS Fig. 2