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December 17,2020
Cuc Construction
Attn: Taylor Parsons
625 Airport Road
Glenwood Springs, Colorado 81601
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Project No. 17-7,866.4
Subject: Observation of Bearing Conditions, Proposed Residence, 28 Eagle Claw Circle,
Lot 251, Ironbridge, Garfield County, Colorado
Dear Taylor:
As requested, the undersigned representative of Kumar & Associates observed the subject site on
December 3,2020 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations fbr the foundation support are presented in this report. The
services were performed in accordance with our ag¡'eement for professional engineering sewices
to Cuc Construction dated December 3,2020. We previously performed a subsoil study for this
site dated January 17,2A18, our Project No. i 7-7-866.
The proposed residence will be a two-story wood frame structure with a structural slab
foundation. The soils at this site consist of compacted structural fill placed between April and
May,2006. The fill placement was observed by H-P Geotech (now Kumar &, Associates). The
fillwas compacted to at least 95% of the standard Proctor clensity.
At the time of our visit to the site, the structural slab foundation was in place. Insulating blankets
had been pulled back and we could see the entire perimeter of the house foundation. The
foundation excavation had beçn cut in one level from 2 to 3 feet below the adjacent ground
surface. The exposed soils adjacent the foundation consisted of sandy silt with gravel. No free
water was observed and the soils were slightly rnoist to moist. Four density tests were performed
with a nuclear density gage on both the north and south sides ofthe foundation. The two westem
tests on the north and south sides of the foundation indicated compaction of 95% of standard
Proctor density. The other two tests performed indicated compaction on the order of 85 to 90o/o.
Our testing technician indicated there were voids under the gage due to the limited test area
available. The drive pin was hard to drive into the soils and it is our opinion that thç in-place fill
soils are compacted properly and the low test results are due to difficulties associated with
getting the gage flat on the ground in the constricted test areas.
Considering the conditions exposed in the open parts of the bearing soils and the nature of the
proposed construction, a structural slab placed on the previously compacted fill designed for an
Cuc Construction
December 17,2020
Page2
allowable soil bearing pressurs of 1,500 psf can be used for support of the proposed residence.
Settlement of I to 1% inches due to long term compressibility of the fill should be expected as
discussed in the previous report. The exposed soils also tend to compress when wetted and there
could be some post-construction settlement of the foundation if the bearing soils become wet.
Exterior footings should be provided with adequate soil cover above their bearing elevations for
frost protection. Continuous for¡ndation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported lengfh of at least 14 feet. Foundation walls
acting as retaining súuctures 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 not be provided for the structural slab-at-grade foundation. Backfill placed around
the structure should be compacted and the surface graded to prevent ponding within at least
10 feet of the building. Landscape that requires regular heavy irrigation, such as sod, and
sprinkler heads should not be located within 10 feet of the foundation.
The findings and recommendations submitted in this letter are based on our observation of the
exposed soils adjacent the foundation and the previous 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 building slab 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. Our services do not include determining the
presence, prevention or possibility of mold or otherbiological 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 assistanceo please call our office.
Sinçerely,
::ìt:t,.ì., .' .,.,, Ìi li,lì .. j:,tiil
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Daniel E. Hardin, P
Rev. by: SLP
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