HomeMy WebLinkAboutObservation of Excavation 09.28.2017H-PKUMAR
Geotechnical Engineering 1 Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
September 28, 2017
Phil and Lisa Ensign
1 South Garfield Street
Denver, Colorado 80209
philensign@gmail.com
Project No. 17-7-561
Subject: Observation of Excavation, Proposed Residence, Lot 23, High Aspen Ranch,
Overlook Drive, Garfield County, Colorado
Dear Mr. and Mrs. Ensign:
As requested, the undersigned representative of H-P/Kumar observed the excavation at the
subject site on September 27, 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. We previously conducted a subsoil study for design of foundations at the site and
presented our findings in a report dated August 7, 2017, Project No. 17-7-561.
At the time of our visit to the site, the foundation excavation for the residence had been cut in
two levels up to 8 feet below the adjacent ground surface. The lower, basement level daylighted
on the south side. The soils exposed in the bottom of the excavation consisted mainly of natural
basalt rocks from cobble to large boulder size in a gravelly sandy clay matrix. Up to 1 foot of
imported, 3 -inch minus slightly silty sandy gravel had been placed and compacted in the
southern part of the basement area and for exterior slab and column pad support on the south side
of the crawlspace area. No free water was encountered in the excavation and the soils were
slightly moist to moist. The garage excavation had not been dug.
The natural 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 2,000 psf. The limited depth of granular fill soils
had been compacted and also appeared suitable for footing support. Loose and disturbed soils
should be moistened and compacted prior to forming footings. 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.
Phil and Lisa Ensign
September 28, 2017
Page 2
We met with Monty Thompson and Phil Ensign at the site and discussed the excavation
conditions and possible winter protection depending on how much of the house construction was
completed prior to winter shut down. The current plan is to complete the house foundation and
get the main floor on and backfill the foundation walls prior to covering the site with winter
protection. It may be possible to also complete the garage foundation, if time allows. In the
event of early winter shut down, only a portion of the work may be done and we discussed what
kind of protection may be appropriate if only the foundation walls are in and not backfilled and
the main floor deck is not in. We expect that the minimum winter protection provided will be
covering the house area with plastic sheeting and providing a drainage path for snowmelt water
to drain to the south side of the building area. It is expected that winter shut down will be around
November Pt. We should update the winter protection recommendations at that time.
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 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,
H -P -4 KU MAR
Daniel E. Hardin, .E.
21 :43
Reviewed by: SLP
DEH/kac
cc: Thunder Construction — Monty Thompson monty@thunderdevelopment.com
Ernie Kollar erniekollar@sopris.net
H-P*KUMAR
Project No. 17-7-561