HomeMy WebLinkAboutB14-0191 Soils Report.pdfkd-old Ow 04- ,t
HHepworth-Pawlak Geotechnical,Inc
5020 County Road 154 Qjj'( i b 6certecf, Glenwood SprgColrado 81601
Phone:970-945-7988
HEPWORTH-PAWLAK GEOTECHNICAL Fax:970-945-8454
email:hpgeo@hpgeotech.com
June 11, 2014
Elk Meadows Development, LLC
Attn: Brian Redinger
141 East Meadow Drive, Suite 211
Vail, Colorado 81657
brian@solarisvail.com
Job No. 114 086A
Subject: Observation of Excavation, Proposed Residence, Lot 1, Elk Meadows
Subdivision, Buffehr Creek Road, Vail, Colorado
Gentlemen:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on June 10 and 11, 2014 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 studyforpreliminarydesignoffoundationsatthesiteandpresentedourfindingsinareport
dated April 18, 2014, Job No. 114 086A. The observation of Lot 1 building excavation
was performed as additional services to our proposal for geotechnical services to Elk
Meadows Development dated March 24, 2014.
The proposed residence will be similar to that described in our previous report and be a
two-story structure above a walkout lower level with a slab-on-grade lower floor. Spread
footings placed on the natural soils and sized for an allowable bearing pressure of 1,500
psf were designed for the building support.
At the time of our initial visit to the site, the foundation excavation had been cut in 2
levels from 3 to 14 feet below the adjacent ground surface. The step in grade was about
21/2 feet down to the northwest with the slope of the natural hillside. The soils exposed in
the bottom of the excavation consisted of relatively dense, silty clayey sand and gravel
with cobbles in the main cut level (5 feet and greater depth) and medium stiff, silty sandyclaywithorganicsinthestepdownareaatthenorthwestside. A metal rod was pushed
down 3 feet into the clay soils by hand with little resistance. Based on the previous
exploratory boring drilled on Lot 1, the clay soils could be 5 feet deep below the cut
depth. Results ofunconfined compressive strength testing performed on a sample of the
clay showed a strength of 700 psf which is medium stiff consistency. When observed on
June 11, the clay area had been sub-excavated about 3 feet to expose the granular soils in
the northeastern part and clay soils in the southwestern part. The clay was probed byhandwithametalrodtoresistanceatabout11/2 to 2 feet below the deeper cut grade. No
free water was encountered in the excavation and the soils were moist to very moist.
Parker 303-841-7119 • Colorado Springs 719-633-5562 • Silverthorne 970-468-1989
Elk Meadows Development, LLC
June 11, 2014
Page 2
The soil conditions exposed in the excavation are generally 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. Footings placed entirely
on the granular soils could be designed for 2,500 psf bearing pressure. Due to the softer
clay soil condition, we recommended placing a geogrid for subgrade improvement
covered with about 2 feet of minus 3-inch aggregate base course compacted to bearinglevel. The exposed soils at cut depth in remaining areas should be compacted prior to
footing construction. Other recommendations presented in our previous report which are
applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils
exposed within the foundation excavation and the previous limited 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 ofpractice should be
consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
HEPWORTH — PAWLAK GEOT ._NICAL, INC.
0 r407 O
Steven L. Pawlak, P.E. a 22 '*'
61 .// t :
SLP/ksw j•Fs , op
Job No. 114 086A
GecPtech