HomeMy WebLinkAboutObservation of Excavation 04.04.2023IC iiffi,*åäfË:iÉrnËü""'
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-e454
email : kaglenwood@kumarusa.com
www.kumarusa.comAn EmployeÊ Ownsd Compony
Offrce l¡cations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
April 4,2023
Terry and Heidi Ruonavaara
1015 Hidden Valley Drive
Glenwood Springs, Colorado 81601
thruonavaara@msn'com
project No.22-7-671
Subject: Observation of Excavation, Proposed Residence, Lot 54, Spring Ridge Reserve,
950 Hidden Valley Drive, Garfield County, Colorado
Terry and Heidi:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on March 30,2023 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation 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 November 16,2022, Project No. 22-7-671.
The proposed residence is similar to that described in our previous report and will be above
crawlspace with slab-on-grade garage designed to be supported on spread footings sized for an
allowable bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation had been cut in one level from
about 3 to 7 feet below the adjacent ground surface in the residence area anddaylighting at the
downhilt, northeast end of the garage area. The soils exposed in the bottom of the excavation
consisted of sandy silt in the residence area and topsoil in the garuge area. Results of swell-
consolidation testing performed on a sample taken from the residence site, shown on Figure l,
indicate the soils are slightly to moderately compressible under light loading with a low collapse
potential when wetted. The laboratory test results are summarized in Table l. No free water was
encountered in the excavation and the soils were slightly moist.
It is recommended to remove the topsoil down to the soils free of organics in the garage area.
The underlying soils exposed in the excavation are consistent with those previously encountered
on the site and suitable for support of spread footings designed for the recommended allowable
bearing pressure of 1,500 psf with a risk of settlement mainly if the bearing soils are wetted.
Loose disturbed soils should be removed in the footing areas. The expose soils should then be
moistened and compacted. Structural fill placed to reestablish design bearing level in the grade
area caÍLconsist of the onsite, non-organic soils compacted to at least 98% of st¿ndard Proctor
density at near optimum moisture content. The bearing soils should be protected from frost and
concrete should not be placed on frozen soils. Other recommendations presented in our previous
report which are applicable should also be observed.
t
I 4:i
Terry and Heidi Ruonavaara
April 4,2023
Page2
The recommendations submitted in this letter are based on our observation of the soils 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
possible changes to recommendations contained in this letter. Our services do not include
determining the presence, prevention 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,
Kumar & Associates, Inc.
Steven L. Pawlak, P.
SLPlkac
Attachment:Test Results
Table 1 - Summary of Laboratory Test Results
Figure 1 -
Kumar & Associates, lnc. :ì Proj*et Ns. 22-7"671
SAMPLE OF: Sondy Cloyey Silt
FROM: Eosl Side
WC = 7.9 %, DD = 99 pcf
UNDER CONSTANT PRESSURE
!
ADDITIONAL COMPRESSION
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DUE TO WETTING
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22-7-671 Kumar & Associates SWELL-CONSOLIDATION TEST RESULTS Fig. 1
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lGrtåiffi ,ffiifËtrnr':iËü*"'TABLE 1SUMMARY OF LABORATORY TEST RESULTSNo.22-7{71so¡L oRBEDROCKTYPESandy Clayey SiltSandy Clayey Silt{PSFIUilCOilFNEDcoltPREsswESTRENGTHt%ìPt¡sTlcINDEXATTERBERG UTÍTSMILK¡UID LIilfTPERCENTPASSING NO.200sla,E$tSAND(%lGRAVEL{ocflNATURATDRYDENSfÍY9989l0l.ìNATURATMOF¡TURECOT{TENT7.99.6East SideWest SideSATPLE LOCATIONBOTTO]II OF EXCAVAIION) "¡Üt .til-. !Ë