HomeMy WebLinkAboutObservation of Excavation Report 05.05.2014HEPWORTH-PAWLAK GEOTECHNICAL
May 5, 2014
Melanie Crandall
999 Valley Road
Basalt, Colorado 81621
elanic Tflaodearthaspen.conl
Subject:
III t. •rtli- '.0 1.1. (.re 1C .hniL II Itt
( wont% 1 i. 1154
t �� nn�} i'td. 1n1.. y1001
I'l lt.l it. `)!l` 945-7l)}1
f -,ti 070 945 "454
L111.ItI IlI}•'Lll!�II�'�llilLll tl''
Job No. 113 392A
Observation of Excavation, Proposed Residence, Lot 10, St. Finnbar Farm,
Garfield County, Colorado
Dear Ms. Crandall:
As requested by Chris Leintz, a representative of Hepworth-Pawlak Geotechnical, Inc.
observed the excavation at the subject site on April 30 and May 2, 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 study for design of foundations at the site and presented our findings
in a report dated December 19, 2013, Job No. 113 392A.
The proposed residence is essentially the same as described in our previous report.
Spread footings placed on the natural gravel soils or on compacted structural fill and sized
for an allowable bearing pressure of 2,500 psf were designed for the building support.
At the time of our visit to the site on April 30, the foundation excavation had been cut in
one level from 2 to 4V2 feet below the adjacent ground surface. The soils exposed in the
bottom of the excavation consisted of silty sandy gravel and cobbles with scattered small
boulders. A small area of free water was encountered in the deeper cut, eastern part of
the excavation. When observed on May 2, structural fill consisting of minus 4 -inch "pit
run" gravel had been placed to design footing grade in the south and east, deeper cut areas
and road base was being placed to fine grade the surface. The pit run material had been
compacted with a vibratory sheepsfoot compactor prior to our site visit. A proof roll of
the foundation fill area with a loaded dump truck showed little deflection, indicating
adequate compaction. Deflection was observed on the interior slab area yet to receive
additional pit run fill which is expected to adequately stabilize the subgrade for slab
support.
The natural gravel soils exposed in the excavation and the compacted structural fill are
consistent with our recommendations and suitable for support of spread footings designed
for the recommended allowable bearing pressure of 2,500 psf. Loose disturbed soils
should be moistened and compacted. Other recommendations presented in our previous
report which are applicable should also be observed.
P,111(er 303-8l1-7119 Color:1dlttSprings 719-633-5562 * Sikerthtirne 9700-46.8 1989
Melanie Crandall
May 5, 2014
Page 2
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,
HEPWORTH — PAWLAK GEOTECHNICAL, INC.
Steven L. Pawlak, P.E.
EN,roic
t4,16' ST C�
•
11(: 15222 S*
SLP/ksw '�;.orrn` Et•po
cc: Chris Lcintz (mv/t(ia,°sopari
Jub No. 113 392A