HomeMy WebLinkAbout; Carlsbad Sewage Plant Bridge Pier; Soils Report; 1971-06-15FOUNDATION SOILS INVESTIGATION
Sewer Line Bridge Pier Carlsbad Sewage Plant Carlsbad, California
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Client: Salkin Engineering Corporation
June 15, 1971 Job No. 71-404-l
0 KG KENNETH G. OSBORNE &ASSOCIATES
TABLE OF CONTENTS
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INTRODUCT*ON-- __________________________________
FIELD INVESTIGATION-----------------------------
LABORATORY TESTING------------------------------
CONCLUSIONS AND RECOMMENDATIONS
Sit- Conditions----------------------------
Subsurface Conditions----------------------
Soil Bearing and Depth of Piling-----------
General------------------------------------
APPENDIX
Boring Log---------------------------------
Boring Location----------------------------
0 KG KENNETH G. OSBORNE &ASSOCIATES
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Job No. 71-404-l Page 1
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INTRODUCTION
This report presents the results of a Foundation Soils
Investigation performed at the Carlsbad Sewage Plant,
Carlsbad, California.
Planned for construction is a bridge pier for the
crossing of a drainage channel with a sewer line. The pier
is to be supported on driven wood pilings.
FIELD INVESTIGATION'
The field investigation consisted of excavating an
exploratory boring to a depth of 20 feet. The boring was
drilled using an 18 inch bucket auger drilling rig. The
majority of the required test information was obtained in
the field by means of a standard penetrometer. The penetro-
meter used was the, standard split-barrel sampler. It was
driven with blows from a 140 pound hammer falling 30 inches.
The number of hammer blows required to drive the-sampler
12 inches is recorded on the boring log as the penetration
resistance of the soil. In addition, bulk samples of the
soils were obtained for laboratory analysis. These soil
samples, together with the standard penetration results served
as the basis for the laboratory testing and the engineering
conclusions contained in this report.
The log of the boring and a plot plan showing approximate
boring location are included with this report.
LABORATORY TESTING
The laboratory testing consisted of performing the material
classification and determining the in situ moisture content of
major soils.
0 KG KENNETH G.OSBORNE &ASSOCIATES
Job No. 71-404-l Page 2
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CONCLUSIONS AND RECOMMENDATIONS
Site Conditions
The location of the bridge support is to be in the center
of the Flood Control Channel. The area is almost constantly
under water due to the downstream restriction of a culvert.
This pond also contains a substantial amount of organic
sewage.
Due to the amount of water and the muddy condition of
the site, the boring was placed.as near the proposed pier
as possible and is considered sufficient to provide the
necessary information.
Subsurface Conditions
The subsurface soils consist mainly of silty sands with
a 2 foot layer of clay at a depth of 5 feet. The soils are
generally wet and the ground water table was encountered at
a depth of 10 feet. Much caving was observed below this
depth. The penetrations indicate that the soils exist in a
loose to moderately firm condition.
Soil Bearing and Depth of Piling
The proposed structure is to be supported on driven wood
piles. The bearing capacity will depend almost entirely on
skin friction between the wood pile and the native soil.
The loading of the individual piles has been supplied
by Salkin Engineering Corporation and is equal to 7500 pounds
per pile. It is expected that piles of at least one foot in
diameter will be used.
For this size pile, calculations indicate that the pile
shall be driven to a depth of at least 20 feet into natural
ground.
0 KG KENNETH G. OSBORNE &ASSOCIATES
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Job No. 71-404-l Page 3
If a different size pile is used, the following formula
for depth of piling applies:
(400 w d = 7)
where "d" is the pile depth in feet and "D" is the average
pile diameter in feet.
The above depth and formula are based on the assumption
that the penetration resistance encountered during the driving
of the piles will correspond with those values encountered
in the preliminary boring. This penetration resistance shall
be checked at the time the piles are driven. If penetration
resistance differs substantially, the depth of piling will
have to be re-evaluated by use of the Engineering News formula.
General
The recommendations contained in this report are based
on the results of field investigation, laboratory testing and
represent our best engineering judgment. If soil conditions
encountered during the placement of piles differ substantially
from those described in this report, this office should be
notified immediately so that appropriate recommendations can
be made.
0B:dhd
Respectfully submitted,
KENNETH G. OSBORNE & ASSOCIATES
L!!ziLgv F*z Osb jorn Bratene Project Engineer
Kenneth G. Osborne R.C.E. 14340
0 KG KENNETH G.OSBORNE&ASSOClATES
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APPENDIX
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0 KG KENNETH G. OSBORNE &ASSOCIATES
- SURFACE ELEVATION
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ORGANIC SEWAGE
lenses
clayey streaks
CAVING from 10'
KENNETH C. OSBORNE & ASSOC:I.\TES
BORING LOG
TEST HOLE NO. 1
Page A
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KENNETH G. OSBORNE & ASSOCIhTr”sS
. JO.3 NO. 1 DATE
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