HomeMy WebLinkAboutObservation of Excavation 10.03.2017H.PVKUMAR 5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 94S7989
Fax (970) 945€454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
October 3,2017
Geotechnlcal Engineering I Engineering Geology
Materials Testlng I Environmental
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0757 County Road 101
Carbondale, Colorado 81623
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Subject:observation of Excavation, Proposed Bedroom Addition, 0757 County Road 101,
Garfield County, Colorado
Dear Mike and Lisa:
As requested, the undersigned representative of H-PlKumar observed the excavation at the
subject site on September 29,2017 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation design are presented in this
report. The services were performed in accordance with our agreement for professional
engineering services to you, dated September 29,2017.
The proposed addition will be a one story wood frame structure with a slab-on-grade floor. The
addition will be attached to the east side of the existing house. 'We understand that a one story
garage is planned on the north side of the new addition
At the time of our visit to the site, the foundation excavation had been cut in one level from 1 to
6 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of very stiff, sandy silty clay. Results of swell-consolidation testing performed on a
sample taken from the site, shown on Figure l, indicate the clay soils have low compressibility
under light loading at existing natural moisture and have a minor collapse potential (settlement
under constant load) when wetted. The sample was moderately compressible under increased
loading after wetting. No free water was encountered in the excavation and the soils were
slightly moist to moist.
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 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. Care should be taken to keep the bearing soils from
becoming wet. Footings should be a minimum width of 16 inches for continuous walls and 2
feet for columns. l¡ose and disturbed soils in footing areas should be removed and the bearing
Mike and Lisa Nieslanik
October 3,2017
Page 2
level extended down to the undisturbed natural soils. The bearing soils should be protected
against frost and concrete should not be placed on frozen soils. Exterior footings should be
provided with adequate soil cover above their bearing elevations for frost protection. Continuous
foundation walls should be relnforced top and bottom to span local anomalies such as by
assuming an unsupported length of at least 12 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 50 pcf for on-site soil as backfill. A perimeter foundation drain should be
provided to prevent temporary buildup of hydrostatic pressure behind any basement walls and
prevent wetting of the lower level. Structural fill placed within floor slab areas can consist of the
on-site soils compacted to at Leasf.9í%o of standard Proctor density at a moisture content near
optimum. Backfill placed around the structure should be compacted and the surface graded to
prevent ponding within at least 10 feet of the building.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
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 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 ñeld of practice should be consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
H-PtKUMAR
E. Hardin, P
DEII/kac
attachment Figure I - Swell-Consolidation Test Results
cc:Schmueser Gordon Meyer - Mindy Nastal
H-PryKUMAR
(mind)¡n @ sgnt-inc,qo¡n)
Project No.17-7-729
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SAMPLE OF: Sondy Silty Cloy
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of Excovoflon
WC = 8.0 %, DÐ = 99 pcf
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17 -7 -729 H-PryKUMAR SWELL-CONSOLIDATION TEST RESULTS Fig. 1
Dave Argo
From:
Sent:
To:
Subfect:
Attachments:
play ball < playballnow22@gmail.com >
Thursday, October 05,20L7 2:44 PM
Dave Argo
Fwd: Excavation Observation,0757 County Road L0L. Garfield County, CO
i rrrage0O 1.p t'rg; L7 -7 -7 29 (10-03 - L7) Exc O bs sig ned.pdf
Dave
Here is the soils report thot we rece,ved From HP Geotech. We will hove it ons¡te for ony
inspections.
Thonk you for your help in this project.
Liso Nieslqnik
Forwarded message
From: Kathy Crisler <kcrisler@kumarusa.o
Date: Thu, Oct 5,2017 at 1:12 PM
Subject: Excavation Observation,0757 County Road 101. Garfield County, CO
To: "Mike Nieslanik (playballnow22@gmail.com)" <playballnow22@gmail@
Cc: "Mindy Nastal (mindyn@sgm-inc.com) " Íqindyn@sgm-inc.o
Please see attached letter. Ifyou have any questions, please call us.
Thank you,
Kathy O
Kathy Crisler
Ad m i n istrat¡ve Assistant
kcrisler@ kuma rusa. com
H-P\KUMAR
H-P/Kumar
5020 County Road 154
Glenwood Springs, Colorado 81601
P: (970) 945-7988 | F: (970) 945-8a54
www.hpkumar.com
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