HomeMy WebLinkAboutObservation of Excavation 03.27.20191(4 A
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Geotechnical and Maindals Engineers
ams Envlranrnernal St;ienisis
5020 County Road .154
Glonwooci :springs, CO 81601
phone: (970) 94£-7988
fax: (970) 94 i-84'51
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March 27, 2019
Custom Works
Attn: Dan Dixon
P.O. Box 508
Carbondale, Colorado 81623
Subject:
Gentlemen:
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Project No. 18-7-561
Observation of Excavation, Proposed Residence, 2395 Highway 133, Garfield County,
Colorado
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the subject site
on March 26 and 27, 2019 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations for the foundation design are presented in this report. These
services were provided in addition to and in accordance with our agreement for geotechnical services
to Custom Works dated September 11, 2018. We previously conducted a subsoil study for design- of
foundations at the site and presented our findings in a report dated September 28, 2018, Project No.
18-7-561.
At the time of our first visit to the site, the building excavation ha.d been cut in one level from 1 to 2
feet below the adjacent ground surface. The soils exposed in the excavation consisted of silty clay. A
pit was dug to 5 feet below adjacent grade to expose the underlying silty gravel and sand
recommended for footing support. At the time of our second visit to the site, the foundation
excavation had been cut in 2 levels from 2 to 5 feet below the adjacent ground surface. The soils
exposed in the bottom of the excavation consisted of silty clay in the upper slab area level, and silty,
clayey sand and gravel in the lower footing areas. No free water was encountered in the excavation
and the soils were moist.
The gravel soil 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 2,500 psf. The spread footing subgrade should be sub -excavated down to the undisturbed gravel
soils and built up to design grade using compacted structural fill. The slab subgrade should be sub -
excavated at least 1 foot and built back up to grade using compacted structural fill. Observations of
structural fill placement are presented in the attached Construction Observation Report. The bearing
soils should be protected from frost and concrete should not be placed on frozen soils. Other
recommendations presented in our previous report which are applicable should also be observed.
Custom Works
March 27, 2019
Page 2
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 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, Inc.
James H. Parsons
Reviewed by;
Steven L. Pawla
JHP/kac
Attachment:
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tisijuctuon Observation Report dated March 27, 2019
Kumar & tws c
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Know 1 d3a mWes,1nt,
Geotechnical and Materials Engi
and Envirsnmenki Seionnsts
kumarusa,corn
5020 Cnunty Rood i 64. f;l;nit voci 5pam's. CO 81501
Phne: (010) 045.7988, Fax: (970) 945.8454
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CONSTRUCTION OBSERVATION REPORT
Client: Custom Works
Attn: Dan Dixon
P.O. Box 508
Carbondale, Colorado 81623
Project No.: 18-7-561 Day: Wednesday
Date: 3/27/19
Page: 1 of 1
Project: Proposed Residence, 2395 Highway 133, Garfield County, Colorado
Weather: Clear, calm, dry Temperature: 55°F at 11:30 am
Construction Activities Observed:
Sub -excavating trenches to natural gravels and placing structural
fill. Clay and silt soils are excavated in approximately 3.5 to 4 foot
wide footing trench. An initial pass is made with the roller to
compact the subgrade. 3 inch minus road base is then placed in 12
inch lifts and compacted with the roller.
Equipment in Use: Cat 308 Mini Excavator, Wacker Mini Roller, Dump Truck
Kumar's Site Activities:
Observation of construction activities and bearing conditions.
Footing trenches are being excavated through the clay and silt to
the granular material. Structural fill is placed in 12 inch lifts and
compacted with a mini roller. Structural fill is 3 inch minus road
base. Granular material is silty, clayey gravel and cobbles.
Structural fill is 3 feet deep in footing areas and will be 1 foot deep
under the slab on grade ground floor.
Verbal Communication: Dan Dixon - Owner
distribution:
Custom Works - Dan Dixon
JHP/kac
James H. Parsons Steven L. Pawlak, P.E.
Field Technician Reviewed By