HomeMy WebLinkAboutCarey Soils Evaluation for Rear Addition.pdf H Hepworth-Pawlak Geotechnical,Inc.
P.O. Drawer 1887
GeS�ech Silverthorne,Colorado 80498
Phone:970-468-1989
HEPWORTH-PAWLAK GEOTECHNICAL Fax:970-468-5891
email: hpgeo4@hpgeotech.com
October 1, 2013
Nett Designs Construction, Inc.
Attn: Mr. Ted Simonett
P.O. Box 2177 nettd@comcast.net
Vail, CO 81658 Job No. 413172A
Subject: Observation of Excavation, Proposed Carey Residence Addition, 2785
Bald Mountain Road, Vail, Colorado.
Dear Mr. Simonett:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on September 30, 2013 to evaluate the soils exposed for
foundation support. The findings of our observations are presented in this letter. The
services were performed in accordance with our agreement for an Excavation
Observation to Nett Designs Construction, Inc., dated September 30,2013. We reviewed
the Structural Plan Sheets Si and revised Sl, Foundation Plan and North Deck
Foundation, respectively,prepared by T. Boyle Engineering, dated August 5, 2013 and
September 13,2013. The structural plans assumed a maximum allowable bearing
capacity of 1,500 psf with a minimum 46 inches of cover for frost protection.
EXCAVATION OBSERVATION
At the time of our site visit,the foundation excavation for the addition had been cut in
two levels for the approximate 16 foot by 16 foot exercise room addition, about 4'/2 to 10
feet below existing grade. The pads for the proposed deck were not excavated at the time
of our observations. The soils exposed in the excavation consisted of brown, slightly
moist to moist, silty to clayey, gravelly sand (SM-SC) with angular cobbles and boulders.
Silty to clayey, gravelly sand fill was observed next to the adjacent foundation wall and
the upper 1 to 2 feet of the excavation. The soils exposed at the base of the excavation
were relatively undisturbed and dense.
The soils exposed at the base of the excavation are relatively undisturbed and are suitable
for support of spread footings designed for the assumed maximum allowable bearing
Glenwood Springs 970-94.5-7988 • Parker 303-841-7119 • Colorado Springs 719-633-5562
Nett Designs Construction, Inc.
October 1, 2013
Page 2
pressure of 1,500 pounds per square foot(psf). Water seepage into the excavation should
be collected and diverted away from the footing areas.
The site topography indicates that deeper fill materials appear to be present at the pads
that will support the proposed deck. The pads for the proposed deck support piers should
be extended below all fill materials and bear on the relatively undisturbed silty to clayey,
gravelly sand with cobbles and small boulders. .
UNDERDRAIN SYSTEM AND DAMPPROOFING
We recommend below-grade construction, such as foundation walls and crawlspace areas
be protected by an underdrain system. We recommend the underdrain consist of a
perimeter drain around the exterior of addition. The foundation drain can connect to the
existing perimeter drain and/or daylighted separately from the existing perimeter drain.
The existing perimeter drain should be repaired where damaged and should be checked to
determine if it properly daylighted.
The perimeter drain system should consist of 4-inch perforated, filter fabric wrapped
drainpipe placed in the bottom of the wall backfill surrounded above the invert level with
free-draining gravel. The drainpipe should be placed at each level of excavation and at
least 12 inches below lowest adjacent finish grade and sloped to the existing perimeter
drain system or daylighted. If the existing perimeter drain system around the exterior of
the building cannot be located, we should be notified to provide additional
recommendations. The drain gravel backfill should be at least 12 inches deep. The drain
gravel should be topped with filter fabric prior to backfilling with the onsite soils. Free-
draining gravel used in the underdrain system should contain less than 2%passing the
No. 200 sieve, less than 50%passing the No. 4 sieve and have a maximum size of 2
inches.
For exterior below grade foundation walls adjacent to the crawlspace, we recommend
dampproofing consist of bituminous material, 3 lbs per square yard, extending from the
Job No.413172A G leTtech
Nett Designs Construction, Inc.
October 1, 2013
Page 3
top of the footing to above ground level. A minimum 6-mil vapor retarder is
recommended for dampproofing of exposed earth in crawlspace construction. We
recommend vapor retarders conform to the minimum requirements of ASTM E1745
Class C material. The vapor retarder should be installed in accordance with the
manufacturers' recommendations.
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.
Sincerely,
HEPWORTH - PAWLAK GEOTECHNI �, '►.
I. 41153II
Chad M. Bringle, P.E. [i; : cc
Office Manager Project Engineer `�c 9<.'•F t) 1[13•'<Qs
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Job No.413172A Gtech