HomeMy WebLinkAboutSoils Report.pdfIF P1!( L_D
July 23, 2014
Maley Building Corporation
Attn: Patrick Maley
P.O. Box 4028
Basalt, Colorado 81621
(maleybuiidinwIj sopris.net)
Job No. 114 267A
Subject: Observation of Excavation, Proposed Exercise Building Lot A, Glen
Exemption, Missouri Heights, 611 Harmony Lane, Garfield County,
Colorado
Dear Patrick:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on July 7, 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. The services were performed in accordance with our
agreement for professional engineering services to Maley Building Corporation, dated
July 7, 2014.
The proposed building will be a one story wood frame structure over a crawlspace.
Foundations were designed for an assumed soil bearing pressure of 1,500 psf We
understand that fill was imported to this site from "The Wilds" project in Basalt.
At the time of our visit to the site, the foundation excavation had been cut in one level
from 4 to 61/2 feet below the adjacent ground surface. The soils exposed in the bottom of
the excavation consisted of whitish tan, silty sand with gravel to boulder size basalt rocks
up to 4 feet in size. It is possible that some of the material at footing grade is imported
fill which is similar to what we would expect the native soils to look like in this area. No
free water was encountered in the excavation and the soils were slightly moist to moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an
allowable soil bearing pressure of 1,500 psf can be used for support of the proposed
structure. The exposed silty sand matrix soils tend to compress when wetted and there
could be some post -construction settlement of the foundation if the bearing soils become
wet. Footings should be a minimum width of 18 inches for continuous walls and 2 feet
for columns. Loose and disturbed soils in footing areas should be compacted or removed
and the bearing level extended down to the undisturbed natural soils. Exterior footings
should be provided with adequate soil cover above their bearing elevations for frost
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Maley Building Corporation
July 23, 2014
Page 2
protection. Continuous foundation walls should be reinforced top and bottom to span
local anomalies such as by assuming an unsupported length of at least 12 feet.
Foundation walls acting as retaining structures should also be designed to resist a lateral
earth pressure based on an equivalent fluid unit weight of at least 50 pcf for on-site soil as
backfill. A perimeter foundation drain should be provided to prevent temporary buildup
of hydrostatic pressure behind the crawlspace walls and prevent wetting of the lower
level. Structural fill placed within floor slab areas (if any) can consist of the on-site soils
compacted to at Least 95% of standard Proctor density at a moisture content near
optimum. Backfill placed around the structure should be compacted and the surface
graded to prevent ponding within at least 10 feet of the building. Landscape that requires
regular heavy irrigation, such as sod, and sprinkler heads should not be located within 10
feet of the foundation.
The recommendations submitted in this letter are based on our observation of the soils
exposed within the foundation excavation and do not include subsurface exploration to
evaluate the subsurface conditions within the loaded depth of foundation influence. This
study is based on the assumption that soils beneath the footings have equal or better
support than those exposed. The risk of foundation movement may be greater than
indicated in this report because of possible variations in the subsurface conditions. In
order to reveal the nature and extent of variations in the subsurface conditions below the
excavation, drilling would be required. It is possible the data obtained by subsurface
exploration could change the 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.
honREr f
EEits,
Daniel E. Hardin, P.E.t
Rev. by: SLP
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Job No. 114 267A
Ge Ptech