HomeMy WebLinkAboutB15-0199_HP Geotech_excavation_observation_1446488100.pdf~tech
HEPWORTH-PAWLAK GEOTECHNICAL
August I I, 2015
Vail Custom Builders
Attn: Clinton Amundson
P. 0. Box 2809
Ed,:vards, Colorado 81632
clinton@vailcustom.com
Hepworth-Pawlak Gcotcchnical. Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970-945-7988
Fax: 970-945-8454
Email: hpgco1!:hpgcotcch.com
Job No. 115 21 lB
Subject: Observation of Excavation, Proposed Residence, Lot 8B, Block 2, Lion's
Ridge, 1463 Aspen Grove Lane, Vail, Colorado
Dear Clinton:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on August 3, 2015 to evaluate the soils exposed for
foundation support. The findings of our observations and recommendations for the
foundation design are presented in this report. The services were perfonned in
accordance with our agreement for professional engineering services to Vail Custom
Builders dated July 30, 2015.
We previously conducted a subsoil study for design of foundations at the site and
presented our findings in a report dated October 17, 2002, Job No. 101 549. The
residence will two story wood frame structure over a basement level. Ground floors will
be a combination of slab-on-grade and structurally supp01ied over crawlspace. The
building has been designed to be supported on spread footings using an allowable bearing
pressure of 2,000 psfbased on recommendations provided in our previous report.
At the time of our site visit, the foundation excavation \Vhich was essentially complete
had been cut in multiple levels from 4 to about 20 feet below the adjacent ground surface.
The materials exposed in the bottom of the excavation consisted primarily of medium
hard to hard, sandstone bedrock. In the southeast comer of the excavation was a limited
area and depth of clayey silty sand soils at subgrade over the bedrock. Results of swell-
consolidation testing performed on samples taken from the site, shO\vn on Figure I,
indicate the clayey silty sand soils are moderately compressible under conditions of
loading and wetting. No free \vater was encountered in the excavation and the soils and
bedrock were slightly moist to moist. We recommended the sand soils be removed to
bear the footings entirely on bedrock and reduce the potential for differential settlement,
which we understand was done.
The bedrock conditions exposed in the excavation are consistent \Vith those previously
encountered on the site and suitable for suppo1t of spread footings designed for an
Parker 303-841-7119 · Colorado Springs 719-633-5562 · Silverthorne 970-468-1989
Vail Custom Builders
August 11, 2015
Page 2
allowable bearing pressure of 2,000 pst: All soil and loose disturbed materials should be
removed in the footing areas to expose the undisturbed bedrock. 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
and bedrock 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,
cc: BPSE -Brian Puppe (brian(d:bpse.net)
.Joh No. 115 ~I JB
~tech
Moisture Content = 9.6 percent
Dry Density = i15 pcf
Sample of: Clayey Silty Sand
From: Bottom of Southeast Portion of Excavation
~
c: .Q 1 CJ)
8-in
I 0
c -i-~ Compression
0 "-"'"''"'"' r--,.b upon "(ii
(/) wetting (J) 1 ..... ~ 0.. E 0 0 2 ~
'\ \ 3 ~ I\~ 4
I I
0.1 1.0 10 iOO
APPUED PRESSURE-ksf
115 2118 ~ HEPWORTH-PAWLAK GEOTECHNICAL.
SWELL-CONSOLIDATION TEST RESULTS Figure 1