HomeMy WebLinkAboutObservation of Excavation 06.23.14H Hei>n'orth-Pnrvlak Getitcr:lrrr ictll. lnc
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June 230 2014
Melissa Hefferon
44525 Highway ó
Glenwood Springs, Colorado 816Ûl
(rnik g@,a sp enrnar'ket ing group - co nr)
Jotr No. 109 t I lA
Subject observation of Excavation, Ptoposed Addition, Lot 3, old orchard
Subdivision, 44525 Highway 6, Garfield County, Colorado
Dear Ms. Heffleron:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc- observed the
.xcavàtion at the subject site on June 16, ?014 to evaluate the soils exposed for
foundation support. tnu ¡o¿lngs of our observations and recommendations for the
foundation design are present*Jin tt i* report. \try'e previously conducted a subsoil study
for design of foındatións at the site and presented our findings in a report dated May 18,
2014, Job No. 109 11 14.
The addition \ryill be attached to the east side of the residence. Spread focrtings placed on
the natural soils and sized for an allowable bearing pressure of 1,000 psf were designed
for the foundation support. Gt'ound floor will be structural above crawlspace'
At the time of our visit to the site, the foundatis¡ s¡s¿vation had been cut in one level
Èom 3 to 6 feet below the adjacent ground surtàce. The soils exposed in the bottom of
the excavation consisted of slfty to ðlayey sand and sandy silt and clay- Results of swell-
consolidation testing perforrneå on a sàmpre of the sandy silt and clay taken from the site'
shown on Figure l,ïdicate low cornpressibility under 1ow moisture content and light
loading witfa low collapse potential when wettcd, and moderate to high coffrpressibility
under additional loading A sample of sand was testetl for silt and clay contcnt with the
results shown ou Table 1. No free rvater was encountered in the excar¡ation aud the soils
were slightly moist.
The soil sonditions exposed in the cxcavation ale consistc-.ot with thosc ptcwiously
ençountered on the site and can be used for support of spread footings designed for the
recoïnmended allowable bearing pressure of r,ooo psf with a settleinent risk mainly if the
soils are wetted. Loose disturbãd soils in the footing areas should be removed and the
exposed soils moistened and compacted. Other recomÛlendations presented.in our
piå"1"u* report which are applicaLle, especially those to keep the bearing soils dry,
should also be observed'
'jtJltl i¡ i ,Ìij¡,1
GARFIE.LD CÜUNTY
TOMMUNITY DEVELOPMENT
parLer 30.3-S4l-?l lç o Colt:rado Sptings ? l9-6J-l-i561 r Sih'erthorne 9?Ll'4óB-1989
Melissa Hefferon
June 23, 2014
Page 2
The recommendations submitted itr this letter are based on our obselation ofthe soils
exposed within the foundatìon excavation and the previous limited subsurface exploration
at ihe site. Variations in the subsurface conditions below the excavation could increase
the risk of foundation movsment, 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, pt'evention or possibility of
mold or other biological contaminants (MOBC) developing in the future. If the client is
concemed about MOBC, then a professional in this special field ofpractice should be
consulted.
If you have any questions or need 1ì¡rther assistance, please call our office.
Sincerely
HEPWORTH _ PAWLAK GEOTECHNICAL, INC.
Steven L. Pawlak, P.E
Rev. by: DAY
SLP/ljg
Attachments: Figure 1 - Swell-Consolidation Test Re'suìts
Table 1 - Summary of Laboratory Test Results
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JobNo. t09 tllA cÆtecr,
HEPWO RTH.PAWLAK G EOTECHN ICAL' INC.TABLE 1SUMMARY OF LABORATORY TE$T RESULTSJob No. 109 l11A'solL oRBÊDROCKTYPESandy Silt and ClaYSílty SandUNCONFINEDCOI,IPRESSIVE' srRENcrHPERCENTPASSINGNO.200SIEVELIMITSUQUIDL[ulTPLASTIC!NT}EX16GSANT}(%)GRAVELt%lNATURALDRYDENSITY10099!{ATURALMOISruRECONTËNTSide7.72.2SAÛIPLE80TïoilOFEXCAVATIONSideSouthNorth-Wesf
{¡)e(DoCJo_-0(uTPOECı.1J[¡5E ào¡b EpE r¡ (d(/)ı*øl-ctrfc^a¡L)ñË,A a:cÈg È,8 Eco'at nØc7'o o'EE-3oO\--*.\ìOo(>Fqot,ñccf,(t)U)t¡Jcco-cltIl=t-o-N\ff?o{ ø } r.¡orssSudn¡oco(0F*d6Ëgui?ãüFl¡lU)53oltJclt--ct)UJt-zotro=oozo()IJUJ3alrJÉf(,tLo)o