HomeMy WebLinkAbout05152soilreport.pdfSOIL AND FOUNDATION INVESTIGATION
FOR THE
PROPOSED HORTON RESIDENCE
PARCEL D, STREAMSIDE DUPLEXES
4284 COLUMBINE DRIVE
TOWN OF VAIL
EAGLE COUNTY, COLORADO
PROJECT NO. 05152
SEPTEMBER 13, 2005
PREPARED FOR:
MR. KYLE WEBB
KH WEBB ARCHITECTS, PC
953 S. FRONTAGE ROAD WEST, SUITE 216
VAIL, CO 81657
LKP Engineering, Inc.
TABLE OF CONTENTS
EXECUTIVE SUMMARY ........................................................... 2
SCOPE OF STUDY................................................................. 2
SITE DESCRIPTION ............................................................... 2
PROPOSED CONSTRUCTION ....................................................... 3
FIELD INVESTIGATION ............................................................ 3
SUBSURFACE SOIL AND GROUNDWATER CONDITION ............................... 3
FOUNDATION RECOMMENDATIONS ............................................... 4
SLAB CONSTRUCTION ............................................................ 4
RETAINING WALLS............................................................... 5
UNDERDRAIN SYSTEM ............................................................ 5
SITE GRADING AND DRAINAGE ................................................... 6
LAWN IRRIGATION ............................................................... 7
LIMITATION ..................................................................... 7
FIGURES
LOCATION SKETCH . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . DRAWING NO. 1
SUBSURFACE EXPLORATION LOGS. . . . . . . . . . . . . . . . . . . . . . . . . . FIGURE NO’S 1 - 3
PERIMETER DRAIN . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . FIGURE NO. 4
LKP Engineering, Inc.
EXECUTIVE SUMMARY
The proposed residence should be supported with
conventional type spread footings, designed for an
allowable soil bearing pressure of 3500 psf. They should
construct the footings on the undisturbed, sandy gravel
with cobbles and boulders. See Foundation
Recommendations.
SCOPE OF STUDY
This report presents the results of a subsurface Soil and Foundation Investigation for a
proposed residence to be constructed on Parcel D, Streamside Duplexes, 4284 Columbine Drive,
Town of Vail, Eagle County, Colorado. The purpose of the subsurface soil and foundation
investigation was to determine the engineering characteristics of the foundation soil and to
provide recommendations for the foundation design, grading, and drainage.
SITE DESCRIPTION
Parcel D is a 0.52-acre lot, at 4284 Columbine Drive, in the Town of Vail, Eagle County,
Colorado. The topography is moderate. Drainage is to the west and southwest. Vegetation on the
lot consisted of pines, aspens and serviceberries. The lot is vacant.
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PROPOSED CONSTRUCTION
We understand that the proposed duplex will consist of a two-story, wood frame
construction, with a walkout basement, on a concrete foundation. Loads are anticipated to be
light, typical of residential construction.
If the finalized plans differ significantly from the above understanding, they should
notify us to reevaluate the recommendations of this report.
FIELD INVESTIGATION
The field investigation conducted on August 10, 2005, consisted of boring, logging and
sampling three test borings. The test boring locations are shown on Drawing No. 1. Drilling of
the test borings was done with a 4-inch diameter, continuous flight, a power auger, on a truck
mounted drill rig. We show the soil profiles of the test borings on the Subsurface Exploration
Logs, Figure No’s one through three. Soil samples for laboratory soil analysis and observation
were taken at selected intervals by advancing Standard Split Spoon and California Samplers
with a 140-pound hammer, falling 30 inches.
SUBSURFACE SOIL AND GROUNDWATER CONDITION
The soil profiles encountered in the test borings were uniform. They consisted of one
foot of topsoil over four to five feet of brown to reddish brown, sandy gravel with cobbles and
large boulders. Refusal on the cobbles and boulders was encountered in all three test borings at
depths of 5, 4, and 4 feet respectively. Ground water was not encountered at the time of drilling.
We sampled the soil in the test borings at random intervals. The soil samples were
brought to our laboratory for observation and analysis.
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FOUNDATION RECOMMENDATIONS
The proposed duplex should be supported with conventional type spread footings,
designed for a maximum allowable soil bearing pressure of 3500 psf. The footings should be
placed on the undisturbed, sandy gravel with cobbles and boulders. We recommend minimum
width of 16 inches for the continuous footings and 2 feet for the isolated footing pads.
Continuous foundation walls should be reinforced top and bottom to span an unsupported length
of at least 10 feet.
A minimum of 48 inches of backfill cover is recommended for frost protection of the
footing subsoils. The undersigned engineer must observe the foundation excavation to verify that
the soil conditions are uniform throughout the foundation excavation.
The foundation excavation should be free from excavation spoils, frost, organics and
standing water. We recommend proof-rolling of the foundation excavation. Soft spots detected
during the proof-rolling, should be removed by overexcavation. Any overexcavation within the
proposed foundation, should be backfilled, in 8 inches loose level lifts and compacted to 100%
of the maximum dry density and within 2 percent of the optimum moisture content as
determined in a laboratory from a Standard Proctor test (ASTM D-698). Structural fill, placed
under footings should be tested by the engineer or her representatives on regular basis. Voids left
at the bottom of the foundation excavation, by the removal of boulders, should be filled with
lean concrete.
SLAB CONSTRUCTION
The natural on-site soils, exclusive of topsoil and organics, are suitable to support lightly
loaded slab-on-grade construction. The subgrade for the slab-on-grade construction should be
proof compacted to detect and remove soft spots. They should backfill overexcavated soft spots
and other underslab fill with the on-site soil, free from topsoil and organics, or other suitable
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material, compacted to a minimum of 95 percent of the maximum standard Proctor density
(ASTM D-698). Suitable material should be free from topsoil, organics and rock fragments
greater than 3 inches.
The concrete slab should be constructed over a 4-inch layer of clean gravel consisting of -
3/4 inch gravel with at least 50% retained on the No. 4 sieve and less than 3 percent passing the
No. 200 sieve.
They should reinforce the concrete slab-on-grade and score control joints according to the
American Concrete Institute requirements and per the recommendations of the designer to reduce
damage due to shrinkage. The concrete slab should be separated from the foundation walls and
columns with expansion joints to allow for independent movement without causing damage.
RETAINING WALLS
They should design foundation walls retaining earth and retaining structures that are
laterally supported to resist an equivalent fluid density of 60 pcf for an “at-rest” condition.
Laterally unrestrained structures retaining the on-site earth should be designed to resist an
equivalent fluid density of 40 pcf for the “active” case.
The above design recommendations assume drained backfill conditions and a horizontal
backfill surface. Surcharge loading due to adjacent structures, weight of temporary stored
construction materials and equipment, inclined backfill and hydrostatic pressure due to
undrained backfill should be incorporated in the design. They should try to prevent the buildup
of hydrostatic pressure behind the retaining wall.
UNDERDRAIN SYSTEM
To reduce the risk of surface water infiltrating the foundation subsoil, the installation of a
foundation perimeter drain is recommended. The foundation perimeter drain (Figure No. 4)
should consist of a 4-inch diameter perforated pipe sloped to a suitable gravity outlet. The drain
should slope at 1/4 inch per foot if flexible or at 1/8 of an inch if rigid pipe is used. The bottom
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of the trench adjacent to the footing should be lined with a polyethylene moisture barrier glued
to the foundation wall. The drain pipe should be placed over the moisture barrier and covered
with a minimum of 6 inches of -3/4 inch free-draining granular material. Geotextile (Mirafi
140N or equivalent) should be used to cover the free-draining gravel to prevent siltation and
clogging of the drain. The backfill above the drain should be granular material to within 2 feet of
the ground surface to prevent a buildup of hydrostatic pressure. The top one foot of the backfill
material should consist of a relatively impervious fill. The backfill should be sloping away from
the building.
SITE GRADING AND DRAINAGE
A grading plan was not available for our review. The following recommendations are
general. The site surrounding the building structure should slope away from the building in all
directions. A minimum of 12 inches in the first 10 feet is recommended in unpaved areas, and
three inches in the first 10 feet in paved areas. The top of the granular foundation backfill
should be covered with a minimum of 1 foot of relatively impervious fill to reduce the potential
of surface water infiltrating the foundation subsoils.
Surface water naturally draining toward the proposed building site or permanent cuts,
should be diverted around and away from it by means of drainage swales or other approved
methods. The roof drains and downspouts should extend and discharge beyond the limits of the
backfill. Exterior backfill should be compacted at or near the optimum moisture content to at
least 95% of the maximum standard Proctor density under pavement, sidewalk and patio areas
and to at least 90% of the maximum standard Proctor density under landscaped areas.
Mechanical methods of compaction should be used. Do not puddle the foundation excavation.
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LKP Engineering, Inc.
LAWN IRRIGATION
It is not recommended to introduce excess water to the foundation soils by installing
sprinkler systems next to the building. The installation of the sprinkler heads should insure that
the spray from the heads will not fall within 10 feet of foundation walls, porches or patio slabs.
Lawn irrigation must be controlled.
LIMITATION
This report has been prepared according to locally accepted Professional Geotechnical
Engineering standards for similar methods of testing and soil conditions at this time. There is no
other warranty either expressed or implied.
The findings and recommendations of this report are based on field exploration,
laboratory testing of samples obtained at the specific locations shown on the Location Sketch,
Drawing No.1 and on assumptions stated in the report. Soil conditions at other locations may
vary, which may not become evident until the foundation excavation is completed. If soil or
water conditions seem different from those described in this report we should be contacted
immediately to reevaluate the recommendations of this report.
This report has been prepared for the exclusive use Mr. Kyle Webb, KH Webb
Architects PC, for the specific application to the proposed Horton Residence on Parcel D,
Streamside Duplexes, 4284 Columbine Drive, Town of Vail, Eagle County, Colorado.
Sincerely,
LKP ENGINEERING, INC.
________________________
Luiza Petrovska, PE
President
J:\WP12-LKP\2005\05152ROCK.rpt.wpd
PARCEL DNORTH
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WETLANDS-BY OTHERSNOTE 9 CREEKNOTE: SITE PLAN PROVIDED BY OTHERS.
LKP
tel (970) 926-9088 fax (970) 926-9089P.O. Box 2837 Edwards, CO 81632
Engineering, Inc.
CIVIL/GEOTECHNICAL
EAGLE COUNTY, COLORADO
LOCATION SKETCH
PROJECT NO.:
~ 1" = 30'SCALE:
DRAWING NO.:1
05152PARCEL D, STREAMSIDE DUPLEXES
4284 COLUMBINE DRIVE
TOWN OF VAIL
FOOTINGFOUNDATION WALL(MIRAFI 140N ORFILTER FABRIC
AT 1/8" PER FOOT FOR RIGID PIPE
4-INCH DIAMETER PERFORATED
WITH LESS THAN 5% FINES
EQUIVALENT)
AT 1/4" PER FOOT FOR FLEXIBLE ANDPIPE SLOPED TO A SUITABLE OUTLET
COARSE GRAVEL, 3/4 INCH DIAM.
GRANULAR FILL
IMPERVIOUS SOIL
FOOT OF RELATIVELY
COVER BACKFILL WITH ONE
SLOPE AWAY FROM BUILDING
PLASTIC LINER, GLUED TO THE FOUNDATION WALL,
PERIMETER DRAIN
FIGURE NO.:
LKP Engineering, Inc.
tel (970) 926-9088 fax (970) 926-9089
CIVIL/GEOTECHNICAL
4
PROJECT NO.:
SCALE:N.T.S.
P.O. Box 2837 Edwards, CO 81632 EAGLE COUNTY, COLORADO
05152PARCEL D, STREAMSIDE DUPLEXES
4284 COLUMBINE DRIVE
TOWN OF VAIL