HomeMy WebLinkAboutObservation of Excavation 06.29.17H-P*KUMAR
Geotechnlcal Enginearing I Engineering Geology
Mata¡lals Testllp I Envlronmantal
47s-7
5020 Counly Road 154
Glenwood Springs, G0 81601
Phone: (970) 945-7988
Fax (970) 945-8454
Email: hpkglenwood@kumarusa.com
OÍice Locations: Parker, Glenwood Springs, and Silverthorne, Colorado
June 29, 2017
Trevor Ruonavaa¡a
160 Spring Ridge Drive
Glenrvood Springs, Colorado 81601
trfinishes €r gmail.con¡
Job No. l'î-7-?3s.Al
Subject:Ob.servation of Excavation, Lot 76, Spring Ridge Reserve PUD, Phase 4,
76 Hidden Valley Drive, Garfield County, Colorado
Dear Trevor:
As requested, a representative of HPlKumar observed the excavation at the subject site on
June 21, 2û17 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations for the foundution 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 April 4, 2017, Project No. 17-7-235.
The proposed re.sidence will be a two-story wood frame structure above a cruwlspace
with an attached garage. The residence rvill have a structural floor over crawlspace with a
slab-on-grade garage fl oor.
At the tirne of our visit to the site, the loundation excavation had been cut in one level
from 2 to 6 feet below the adjacent ground surface. The soils exposed in the botfom of
the excavation consi.sted primarily of silty, clayey sand with gravel, Fractured sand.çtone
bedrock was exposed in the uphill, southeast portion of the excavation. No free rvater
was encountered in fhe excavation and the soils rvere slightly moist.
The soil conditions exposed 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 pÍessure of I,200 pounds per r;quare foot with the risk of
settlement as described in our previou.s report. Loose and disturbed .soils should be
removed in the footing areas to expose the undislurbed natural soils. The base of the
foundation excavation should be moisture conditioned lo neí¡r optimum and re-compacted
prior to placement of reinforcing steel and concrele. Due Lo the potential for differential
settlement of the foundation between areas founded on native soil and areas founded on
Trevor Ruonavaara
June29,2017
Page 2
fractured bedrock, we recommend that footing lines that transition fronr bedrock to soil be
designed with additional reinforcing steel equivalent to twice the normal footing
reinforcing bar. Proper design and construction to prevent rvetting 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 reporl. which are applicable should also be observed.
The recommendations submitted in this letter are based 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 increå.re 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 cont¿rmin¿¡nts (MOBC) developing in the future.
If the client is concerned about MOBC, tben a professional in this special field of practice
should bc consulted,
If you have any questions or need further assislance, please call our office.
Sincerely,
HEPWORTH _ PAV/LAK L,INC.
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Jame.s A. Parker, P.E., P &
Reviewcd by:*/t
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Steven L. Pawlak, P.E.
JAPlkac
cc:GarfieldcountyBuildingDepartment*JimWilson@)
Teruy Heidi Ruonavaara (thruonçJaara@ msn.com)
H.PIKUIVIAR
Project No. 17-7-235.01