HomeMy WebLinkAboutObservation of Excavation 03.03.2017H-PryKUMAR 5020 tounty Road 154
Glenwood Springs, C0 81901
G€olachnicsl Englneedng I EnglnEering Geology
Matsrlals Tsstir€ | Environmantal
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March 3,2017 ûffice Locations: Parker, Glenwood Springs, and Summit Count¡ Colorado
Crystal Constructors
Attn: John Placek
725 Spring Park Ridge
Carbondale, Colorado I I 623
cry ptglconçt@F op¿i s. neÎ
Projecr No. 17-7-2ll
Subject:Observation of Excavation, Proposed Barn, Lot 7, Roaring Fork Preserve, I l0
Weeping Willorv Lane, Garfield County, Colorado
Dear Mr. Placek:
rls requested, a representative c¡f FÍ-P/Kunrar observed tire excavation at the subject site on
March 3, 2û17 to evaluate the soils exposed far foundation supperÍ.. The finclings ol'our
obscrvations and recommenclations for the foundation design are presented in this reporl. The
services rvêre perfurrned in accordance rvith our agreenrent for prof"essional engineering servicçs
to CrystalConstructc¡rs, clated February 28,2017" Heprvorth-Parvlak Geoteclurical(norv H-P/
Kumar) previously performed a subsoil study for f'cundation design of tlre residence and
cletached garage located on the site and reported the findings November 29,2tü6, Job No. 106
CI943.
The proposed barn rvill be a onc and trvo story rvood tianre structure. Ground floor rvill be slab-
on-graele. üracling for the structure is relatively minor rvittr cut depths around 3 l"eet. Vúe
assume relatively light foundation loadings, typical of the proposed type of construction. A
maxinrum soil bearing pressure of 2,000 psf rvas used for the lboting design.
At the time of our visit to tlre site, the foundation excavation had been cut in 3 levels from l % to
3 f'eet below the adjacent ground surface. l'he soils exposed in the bottorn of the excavation
eonsisted of silty sandy gravel and cobbies. 'fhere was about I /: feet of loose sols above the
relatively dense gravel. No free water was encountered in the excavation and the soils were
stightly moist.
Considering the soil conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural gravel soil designed for an
allcrvable scil bearing pressure of ?,000 psf,can be used for support of'the proposed barn. T'he
exposed soils should have relativeiy iorv eompressibility under load and post-construclion
seltlemenl of the foundation slrould be relatively rninor. Footings should be a ¡ninirnum width of
l6 inches for continusus rvalls and 2 lbet for columns. Loose and disturbed soils in footing areas
should be renraved and the bearing level extended dr¡rvn to the r¡nriisturbed natural soils. The
Crystal Conslructors
ffilayt7
Fage 2
bearing soils should be protected against ftsst and concrete sliculd not be placed on frozcn soils.
Exterior footings should be provicled rvith adequate soil cover above their bearing elevations for
frost pratection. Continuous foundation rvalls should be reinlorced top and bottom to span local
anomalies such as by assuming an unsupported length of al least l0 feet. Foundation rvalls
acting as retaining struetures {if any) shoukl also be designed to resist a lateral earth pressure
based on ãn equivalenl fluid unit weight of at least 45 pcf for on-site soil as backfill. Structural
f!ll piaced within fïoor slab areäs cån consist of the on-site soils devoid of topsoil and oversize
rcck compacted tc at least 95% of standard Proctor density at a moisture conlent near optimum.
Backfill placed arçund the structure should be compacted and the surlace graded to prevent
ponding within at least 10 feet of the barn.
The reccmmendations submitted in this letter are based on our observatio¡r cf the soils exposed
rvitliin the founcïation excavation and do not include subsurface exploration to evaluate the
subsurface eonditions rvithin the loaded depth of foundation influence. This study is based on
the assumption that soils beneath the footings have equal or better suppcrt than those exposed.
The risk of fcundation rnovement 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 belor,v tl:e excavation, drilling rvould be reqrrired. It is possible the
data übtâined by subsurface exploration could change the recommendations contained in this
letter. Our services do not include deternrining the presence, frrevention or possibility of mold or
other biological contaminants (h{OBC) developing in the fi¡ture. lf the client is concerned about
IvlOBC, then a professional in this special fTeld of practice shoulcl be consulted.
lfyou have any questions or need fnrther assistance, please call our nffîce.
Sincerely,
ü-I.P+ KUMAR
w,tB
Robert L. Duran, lì.1
Revierved by
Steven L. Farvlak, P.
RLD/kac
| 612¡
3 7
H-P*KtlfvtF,R
Froject f{a.1V-7-211