HomeMy WebLinkAboutObservation of Excavation 05.12.16~btech
HEPWORTH-PAWLAK GEOTECHNICAL
May 12, 2016
I
Tom Re4d
635 East 4th Street Road
Eaton, Co. 80615
(mrman635 @ms n.com)
Hep1n1r1h-l'.11dak Geol<·dum.11, lnL
5020 County Road I 54
Cilet11rn<1d Spring,, Color;1do 0 l 6l) I
Phone: 970-945-798S
F.t\: 970-945-0454
L'llla1I : hpgl•o11hpgentt'L h.uim
Job No. 116 177A
Subject: Observation of Excavation, Proposed Residence, Lot 2, Overview
Subdivision, 8382 County Road 115, Garfield County, Colorado
Dear Mr. Reed:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on May 9, 2016 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 July 31, 2007, Job No.
107 0440.
The proposed residence will be one story wood frame construction above a walkout
basement. Basement floor will be slab-on-grade.
At the time of our visit to the site, the foundation excavation had been cut in one level
from 4 V2 to 7 feet below the adjacent ground surface with a small stepped down area at
the southwest corner. The soils exposed in the bottom of the excavation consisted of
clayey sandy gravel with cobbles and boulders. The results of a gradation analysis
performed on a sample of clayey sandy gravel with cobbles (minus 5 inch fraction)
obtained from the site are presented on Figure 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 consistent with those previously
encountered on the site and suitable for support of spread footings designed for the
recommended allowable bearing pressure of 1,500 psf. Loose and disturbed soils should
be removed in the footing areas to expose the undisturbed natural soils. Other
recommendations presented in our previous report 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 (limited) subsurface
exploration at the site. Variations in the subsurface conditions below the excavation
could increase the risk of foundation movement. We should be advised of any variations
Parker 303-841-71I9 • Cnlor,11..lo Springs 7 l 9~633~5562 • Silverthorne 970-468-1989
Tom Reed
May 12, 2016
Page 2
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,
HEPWORTH -PAWLAK GEOTECHNICAL, INC.
Reviewed by:
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Daniel E. Hardin, P.E.~! :,D •·44 '13 z: ~
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attachments Figure 1 -Gradation Test Results
cc: Glenwood Structural & Civil -Adolfo Gorra (!! .... c@ s o 12 ri~.net )
Job No. 116 177A
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HYDROMETER ANALYSIS S EVE ANAL YS S
CLEAR SQUARE OPENINGS I
24
1 7HR TIME READINGS I US STANDARD SERIES I
O 45 ~~ 15 MIN 60MIN19MIN 4 MIN. 1 MIN #200 #100 #50 #30 #16 #6 #4 3/B' 3/4' 11/2' 3' 5·5• a· lOO
10
20
30
40
50
60
70
BO
90
100
001 002 005 009 019
CLAY TOSI.I
GRAVEL 68 %
LIQUID LIMIT
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300 ,600 1.18 2 36 4 75 95 190 37.5
12 .5
76 2 152 203
127 .037 .074 150
D tAMETER OF PARTICLES IN Mi!.L IMETERS
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GRA\1'! I COOBH S .,~ I ~.
SAND 15 % SILT AND CLAY 17 %
% PLASTICITY INDEX %
SAMPLE OF: Clayey Sandy Grave f with Cobbles FROM : Bottom of Excavatton, East Side
90
80
70
60
50
40
30
20
10
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116177A o6'~ GRADATION TEST RESULTS Figure 1
HEPWOR'TM-PAWLAK GEO'TECHNICAL