HomeMy WebLinkAboutOpen-Hole ObservationEngineering, Inc.
CIVILJGEOTECHNICAL
November 8, 2012
Mark L. Courtney
Courtney Construction, Inc.
2272 Holland Drive
Carbondale, CO 81623
Dear Mark
RE: Open Hole Observation/Foundation Investigation
Lot 44, Kings Row Subdivision, Filing #1
1080 Kings Row Street
Garfield County, Colorado
Project No. 12064
At your request, on November 6, 2012, we visited the construction site at 1080 Kings
Row Street, Garfield County, Colorado. The purpose of our site visit was to observe and test the
soils exposed in the foundation excavation for the proposed garage addition in order to verify the
assumed design bearing capacity.
The observed excavation for the proposed addition was on the west side of the existing
residence, with overall dimensions of about 35 by 45 feet. On the east side of the excavation,
adjacent to the existing building, the bottom of the excavation was at the bottom of the existing
foundation. The soil exposed at the bottom of the excavation was variable. Approximately the
northwest half of the excavation was into gypsum matrix with large basalt cobbles and boulders.
On the southeast part of the excavation, the soil consisted of reddish brown sandy clay with
variable amounts of gypsum. Ground water was not observed in the excavation.
Soil samples were taken from the middle south part of the excavation, the southeast and
northwest corners. The soil sample were tested for natural moisture content, natural dry density
and swell/consolidation. The test results are appended to this report. According to the structural
drawings by Ernie Kollar Engineers, Inc., dated 10-19, 2012, the proposed addition was
designed for an assumed bearing pressure of 2000 psf. Based on the test results the reddish
brown, sandy clay is suitable for the designed bearing pressure of 2000 psf. The west part of the
foundation must be redesigned for a maximum allowable soil bearing pressure of 800 psf. The
800 psf bearing capacity must also be used for a minimum distance of 10 feet to the east of the
southwest corner. Also, the foundation walls at the overlapping bearing capacity section must be
reinforced top and bottom and overlap horizontally at the corner.
We recommend a minimum of 48 inches of backfill cover for frost protection of the
footing subsoils. Soft spots were not reported.
Foundation walls retaining earth and retaining structures that are laterally supported
should be designed to resist an equivalent fluid density of 60 pef 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
F.O. Box 2837, Edwards, CO 81632 Tel (970) 926-9088
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LKP Engineering, Inc.
Swell/Consolidation Test Results
QCT Na:
12064
WAVE ,a:
1
0.1 10 10 100
APPLIED PRESSURE — ksf
Sample oh Brown, sandy clay from: S-1 AT MIDDLE SOUTH OF
Natural Dry Unit Weight = 102.4 pcf EXCAVARON
Natural Moisture Content = 10.2 percent
0.4% swell 0 1.6 ksf Swell Pressure
LKP Engineering, Inc.
Swell/Consolidation Test Results
QCT Na:
12064
WAVE ,a:
1
0.1 1.0 10 100
APPLIED PRESSURE — ksf
Sample of: Brown, sandy clay from: S-2 AT SE CORNER
Natural Dry Unit Weight = 88.9 pcf
Natural Moisture Content = 12.7 percent
LKP Engineering, Inc.
Swell/Consolidation Test Results
QCT Na:
12064
WAVE ,a:
1
0.
SLOPE AWAY FROM BUILDING
OVER BACKFILL WITH A
MINIMUM OF ONE FOOT OF
RELATIVELY IMPERVIOUS SOIL
GRANULAR FILL
FIL TER FABRIC (MIRAFI
/ 140N OR EQUIVALENT)
FOOTING
D P
a
•
P
?vx/X/X/X/X/%
30 MIL MINIMUM THICKNESS,
PLASTIC LINER, GLUED T
7HE FOUNDATION WALL
MINUS 3/4 --INCH DIAMETER, COARSE,
CLEAN CRUSH ROCK
-INCH DIAMETER PERFORATED PIPE SLOPED
TO A DAYLIGHT LOCATION AWAY FROM THE
FOUNDATION AT 1/4 -INCH PER FOOT FOR
FLEXIBLE AND 1/8 -INCH MINIMUM FOR RIGID
PIPE
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.O. Box 2837 Edworde, CO 81832
tel (970) 926-9088
PERIMETER DRAIN
MUM ADDITION
LOT 44, KINGS ROW SUBDIVISION, 1ST FILING
1080 KINGS ROW STREET
GARFIELD COUNTY, COLORADO
Warr NO:
12064
SCALD N.T.S.
nova Na:
3