HomeMy WebLinkAboutObservation of Excavation Revised 07.10.17H-PVKUMAR
Gsoteclrnlcal Englneadng | Ënglneering Geology
Maleríals Testing I Envlonmental
5020 Coung Road 154
Glenwood Spdngs, C0 81601
Phon$ (970) 945-7988
Far {970} 945-8454
Email: hpkglenwood@kumarusa.com
Office Locatiom: Parker, Glenwood Springs, and Silverthorne, Colorado
June29,2Al7
Revised: July lü,2017
Trevor Ruonavaara
160 Spring Ridge Drive
Glenwood Springs, Colorado 81601
trfinishe$ @ email.co¡n
Job No. 17-7-235.01
Subject:Observation of Excavation, Lot 76, Spring Ridge Reserve PUD, Phase 4,
76 Hidden Valley Drive, Carfield County, Colorado
Dear Trevor:
As requested, a representative of HP/Kumar cbserved the excavation at the subject site on
June 2l ,2017 to evaluate the soils exposed for foundation support. The hndings of our
observations and recommendations for the foundation design are presented in this report.
Vy'e previously conducted a subsoil study for design of foundations at the site ¡lnd
presented our findings in a report dated April 4,2A17, Project No. l7-?-235.
The proposed residence will be a two-stqry wood frame structur€ above a crawlspace
with an attached garage. The residence will have a structural floor over crawlspace with a
slab-on-grade garage floor.
At the time of our visit to the site, the foundation excavation had been cut in one level
from 2 to 6 feet below the adjacent ground surface. The soils exposed in the bottom of
the excavation consisted primarily of silty, clayey sand with gravel. Fractured sandstone
bedrock was exposêd in the uphill, southeast portion of the excavâtion. No free water
was encountered in the excavation and the soils were slightly moist.
The soil condition.s expo.sed in the excavation are consistent with those previously
encountered on the site and can be used for support ofspread footings designed for the
recommended allowable bearing pressure of 1,200 pounds per square foot with the risk of
settlement as described in our previous report. Loose and disturbed soils should bs
removed in the footing areas to expose lhe undisturbed natural soils. The base of the
foundation excavation should be moisture conditioned to neâr optimum and re-compacted
prior to placement of reinforcing steel and concrete. Due to the potential for differential
Trevor Ruonavaara
lsne29,2tl7
Revised: July 10,2017
Page 2
settlement of the foundation between areas founded on native soil and areas founded on
fraclured beclrock, we recommencl that the fcrr¡ndatinn beam system be clesigned with
reinforcing steel sufficient to span local anomalies, such as by assuming an unsupported
length of at least l4 feet. Proper design and construction to prevent wetting of the
foundation bearing soils during and after construction will be critical to reduce the
potential for differential settlement across the structure. Other recommendations
presented in our previous report which are applicable should also be observed.
The rccommendations submitted in this letter are b¡sed on our observation of the
materials 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 pos.sible changes to recommendations
contained in thi.s letter. Our services do not include determining the presence, prevenlion
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 - PAV/LAK INC.
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James A. Parker, P.E., P e-'"f kwg
Reviewed by:#*/.rcl!
Steven L. Pawlak, P.E.
JAPlkac
cc: üarfield Ccunty Building Department - Jim Wilson {jryilsen@g.arfield-copnty,cqm}
Teny Heidi Ruonavaar¿ (thruonavaara@mln.cg,n)
Jack Albright, Albright & Associates tiâçh@ albrieht-rlsspciates.cpmi
H-PåKUMAR
Project No. 17-7-235.01