HomeMy WebLinkAbout; Chestnut Ave Multi-Residential; Soils Report; 1981-11-11LIMITED SOIL RECIYlNAISSA"CE
307 CHESTNUT AVENUE
CARLSBAD, CALIFORNIA
SDE 2349
PREPARED FOR
JIM STAVER
TORREY PACIFIC PROPERTIES
1240 MELBA ROAD
ENCINITAS, CALIFORNIA
SAN DIEGUITO ENGINEERING, INC.
PO BOX 2004 RANCH0 SANTA FE, CALIF.
(714) 756-3064
ENGINEERING DEPT. LIBRARY
City of Carlsbad
2075 Las Palmas Drive
CarlsbaQ CA 92009-4859
5
John 6. Fox P.E.
Stephen D. Dlllemulh P.E,
.Jame~ A. Laret - P.E.
SAN DIEGUITO ENGINEERING, INC.
AVENIDA DE ACACIAS
PRO. BOX 2004 RANCH0 SANTA FE, CA 92067
756-3064
CIVIL ENGINEERING
SURVEYING
SOIL TESTING
SDE 2349
November 11, 1981
James Staver
1240 Melba Road
Encinitas, CA 92024
SUBJECT: Report of Preliminary Soil Investigation proposed multi-residential
site, CHESTNUT AVENUE, Carlsbad, California.
Mr. Staver:
In accordance with your request we have performed a Preliminary Soil In-
vestigation at the subject site loca,ted at 307 Chestnut Avenue, Carlsbad, Ca.
The purpose of this investigation was to identify any potential soil problems
and provide foundation design criteria. Based on field and laboratory data
the site appears suitable for the proposed development provided the recommenda-
tions contained in this report are incorporated into site development.
* SITE DESCRIPTION
The site is a rectangular parcel, approximately 60' x 326'. The lot is bordered
on the north by Chestnilt Avenue, to the west is an apartment house and to the
east are single family residences. The lot is fairly level and clear. There
are some miscellaneous debris and evidence of previous cultivation. The approx-
imate configuration of the site is shown on Plate 1.
FIELD RECONNAISSANCE
The soils on the suite were examined to a maximum depth of '15' in two trenches
excavated with a backhoe. The soils encountered were visually classified
according to the unified soil classification system. Detailed logs of the
borings were recorded during excavation and are presented on Plates 2 and 3
attached at the end of this report. Trench locations are shown on Plate No. 1.
SDE 2349 11 November 1981 Page Two
SOIL CONDITIONS
Soils encountered on the site consist of brown to orange brown silty medium to
fine sand, these are quaternary beach terrace deposits typical of the Carlsbad
coastal area. The deposits are typically massive, slightly to moderately dense,
and friable. The top 1 l/2 to 3 feet are in a dry loose condition.
LABORATORY AND FIELD TESTING
Tests performed on soil samples to determine existing conditions were:
(1) Maximum Dry Density, (2) Dry Density, and (3) a Direct Shear Test. Procedures
and results of the tests are as follows:
1) A maximum dry density test was performed on a representative sample
returned to the lab. The results of the test, performed in accordance with
A.S.T.M. Test Method D-1557-70, are as follows:
Sample Location
T-Z @ 2
Maximum Dry Density (pcf) Optimum Moisture (%)
131.4 I 9.4
2) Dry Density tests were performed on wax coated chunk samples using
a water displaceme,it method'to determine the existing conditions of the pro-
posed foundation soils. The results of the tests, performed in accordance
with accepted engineerinq practice are as fol'ows:
Sample
Location
T-l I? 3'
T-l @ 10'
T-2 @ 1 l/2'
T-2 @ 7'
Field Dry
(pcf) Density
109.8
94.3
99.9
.lO9.9
Field Moisture
Content (%)
a.7
5.8
6.2
7.9
SDE 2349 11 November 1981 Page Three
3) A Direct Shear test was performed on the proposed foundation soils at
the natural density and moisture content. The sample was returned to
the lab and remolded to the natural conditions. The results of the test,
performed in general accordance with accepted engineering practice, are
as follows:
Sample
Location
T-2 (h 2'
Density Condition Angle of Internal Apparent Cohesion
Description (pcf) Friction 0 _ c (psf)
Remolded to 90% of 35O 100
M.D.D.
CONCLUSIONS AND RECOMMENDATIONS
From a Geotechnical standpoint, the site appears suitable for the proposed
development provided the following recommendations are incorporated into the
site development.
Grading
Topsoil encountered to depths of 1 l/2 to 3' wai found in a dry, relatively
loose condition. This soil should be excavated to firm material, moistened,
mixed and replaced as compacted fill prior to placement of concrete, foundations,
or paving. All grading should be performed according to the grading provisions
attached hereto, and the applicable grading ordinance.
Foundations
The proposed structure may be iupported by conventional continuous or isolated
spread footings, founded a minimum 18" below lowest adjacent grade into firm
natural soil or compacted fill.
Footings may be designed for an allowable soil bearing pressure of 1500 psf.
SOE 2349 11 November 1981 Page Four
Minimum foundation reinforcement should consist of 1 #4 bar placed 1 l/2" below
top and 1 #4 bar placed 3" above the bottom of continuous footings.
An allowable lateral bearing pressure of 300 psf per foot of depth may be
assumed provided footings are poured tight against strrounding firm soils.
A coefficient of sliding friction of .35 may be assumed between concrete and
underlying soils.
Lateral bearing may be increased by l/3 for short term wind and seismic loads.
Slabs
. Slabs on grade should be a minimum 4" thick and reinforced with 6 x 6, lO/lO
welded wire mesh placed at the center of slab crossection.
Slabs should be underlain by a 4" layer of l/4" crushed rock or gravel. A
6 mil thick plastic or vinyl moisture barrier overlain by 2" of clean sand
should be provided over the base material.
Retaining Walls
The following table is provided for equivalent fluid pressures for design of
unrestrained retaining walls with level or sloping backfills. These figures
assume adequate drainage and backfill consisting of compacted free draining
sandy soils.
Slope of Backfill
(Horizontal to Vertical Units)
Fluid Density
(lbs/cu.ft.)
Level 35
5 to 1 37
4 to 1 40
3 to 1 43
2 to 1 48
1 l/2 to 1 60
SDE 2349 11 November 1981 Page Five
Restrained retaining walls retaining level backfill of free draining sand may
be designed for an equivalent fluid pressure of 60 pcf.
Any surcharge loads affecting the retaining walls should be added to the above
values. Retaining walls should be provided with adequate drainage.
The top of the retaining wall backfill wedge should be a minimum 0.; 6/10 of
the wall height and be compacted to at least 90% of the maximum dry density.
On site soils are suitable for backfill of retaining .Jalls provided they are
free of organic or other debris.
Drainage and Erosion
The site should be provided with positive drainage to direct wa::er away from
building areas to a suitable point of discharge. Water should riot be allowed
to pond or run in an uncontrolled manner over slopes.
The on site soils a 'e friable and may be subject to erosion hazrlrds on newly
constructed slopes. All slopes should be planted irmnediately aiter grading. *
LIMITATIONS AND UNIFORMITY OF CONDITIONS
The recommendations of this report pertain only to tha site invr,stigated and
are based upon the assumption that the soil condition: do not dtviate from
those observed in the test pits. IF any variations 01‘ undesiratle conditions
are encountered during construction, or if the proposed construction will
differ from that planned at the present time, San Diel:uito Engiaeering Inc.,
should be notified so tlat supp-emental recommendatior,s can be siven.
This report is issued with the understanding that it s the responsibility of
the owner, or of his relpresentative, to ensure that tie information and re-
commendations contained nerein are brought to the attrntion of the architect
and engineer for the prrject and incorporated into the plans, and that the
necessary steps are taken to see that the contractor znd subcontractors carry
out such recommendation: in the field.
SDE 2349 11 November 1981 Page Six
The findings of this report are valid as of the present date. However, changes
in the conditions of a property can occur with the passage of time, whether
they be due to natural processes or the works of man on this 01' adjacent
properties. In addition, changes in applicable or appropriate standards may occur,
whether they result from legislation or the broadening of knowledge. Accord-
ingly, the findings of this report may be invalidated who!ly 01' partially by
changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
If you have any questions regarding this report, please do not lesitate to
contact this office.
This opportunity to be of service is greatly appreciated.
Respectfully submitted,
SAN DIEGUITO ENGINEERING, INC.,
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lb;
Pf?l-J&
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PROposes )(ouuWS APPARTMEUT 0 li
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OWAIER: ToRWGS( F%iFlC .PRop~f?Tl=S~
I 240 MEL- ROAD
mJa~\TAS CA. 92024
TEL:C7/4) -753-7bb8
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atd IXEGulra EN’+. IUc
t?%wC+b SWTA FE
CA. q2067
TEL:<7/4.> 73b-3064
l&END: ---
8: TEST LOCATIOEJ
1 , ., PRVEW ..Staver JOB ,# SDE: 2349 LOCGED BY: Lc
BOPING'NO,; ~ T-l LCJCHTION: See Plate No. 1 ;j'XCA~VATION DATE; 11/3/81 --
color, grain size, cosolidation, moisture ', @8&&i uses ::; .__.-_-. __-_.-- __._ --.I.--.- I_
loose, dry
--
maple
Orange brown silty med. to fine sand loose, dry
Orange brown slightly clayey medium to fine sand 1, * moderately dense, moist
Light brown to yellow brown slightly silty medium to fine f
sand moderately dense, moist
t ‘:
Dark yellow brown medium to fine sand dense, moist ,
H .I Limited of Excavation 15 Feet.
. ---~.-
. .
-__ - LL _-_-~--. ,..~ ...,. .~. ,. ._,_ . ..___. ~,~._
SAN ~IEGUITO &JNEERIN,, INC.
B-CURING LOG ---I .
_. PHWECT,I Sta,ver JOB # SDE: 2349 LOGGED BYt Lc
BORING N0.i T-2 I,OCATIONI See Plate.1 EXCAVATION DATI ------ SOIL DESCRIPTION;
color. grain size, cosolidation. moisture
Dark brown silty fine sand, loose, dry
Orange brown slightly silty medium to fine sar?d firm,
moist
Dark yellow brown medium to fine sand moist, moderately
L dense
Limit of Excavation 7 Feet.
___ .._..._~ .,.. .,.. ~~~~ -~--~~-~-~~,.-..~__-. _._ - .- .-...,
Si ti DIEGUITO ENGJNEERING, IM.
11/3/81
L
+.
--
triple
RECOKHENDED GRADINC~ SPECIFICATION - GENERAL PROVISIONS
GENERAL INTENT:
The intent of these specifications is to establish pro-
cedures for clearing, compacting natural ground, preparing
areas to be filled and placing and compacting fill soil to
the l-ines and grades shown on the accepted plans. The
recormlendations contained in the preliminary soil invest-
igation report and/or the attached special provsions are a
part i,f,the recommended grading specifi~cations and shall
supersede the provisions contained herc,inafter i.n the case
of cotflict.
INSPECTION AND TESTING ---
A qualified soil engineer shall be employed to r.bserve and
test the earthwork in accordance with these sperifications.
It will be necessary that the soil engineer or his repre-
sentative provide adequate observations so that he may
provide a memorandum that the work was or was net accom-
plishcii as specified. It shall be the responsitility of the
contractor to assist the soil engineer and to keep him
appraised of work schedules, changes and new information and
data so that he may provide the memorandum to the owner and
proper county authorities, as required.
If, in the opinion of the soi. engineer, substandard con-
ditions are encountered, such as questionable soil,' poor
moisture: contl-01, inadequtire compaction, adverse weather,
etc., he will be empowerecl c:o either stop construction until
the col>dit:ion:: are reruedi& or corrected or recommend rejection
of the worii.
Soil lz,lStiS us~jd to tletermiile the degree of compaction will
be pe~r<ormeJ in accordance with the following American
Society for Testing and Htirerials test methods:
Maximum Dry Density and Optimum Content.
A.S.T.M. D-1557-70
Density of Soil In-Place
A.S.T.M. D-1556-64
PBEPARATION OF AREAS TO RECEIVE FI'LL:
All vegetation, brush and debris shall be removed, piled and
burned or otherwise disposed of. After clearing, the natural
ground shall be scarified to a depth of 6 inches, brought to
the proper moisture content, compacted and tested for the
minimum density specified in the special provisions or the
reccmmendations contained in the preliminary soil investi-
gation report.
When the slope of the natural ground receiving fill exceeds
20% (5 horizontal to 1 vertical), the criginal ground shall
be stepped or benched as shown on the attached Plate A.
Benches shall be cut to a firm competent soil condition. The
lower bench shall be at least 10 feet wide and all other
benches at least 6 feet wide. Ground slopes flatter than
20% shall be bencherl when considered necessary by the soil
engineer.
FILL MATEIUAL: ------
l
Materials placed in the fill shall be approved by the soil
engineer ;tnd shall be free of vegetable matter and other
deleterious substances. Granular soil shall contain suffic-
ient fine material to fill t:le voids. The difinition and
dispcsitiL)n of oversized rocks, expansive and/or detrimental
covered in the special provisions. Expansive
ils of poor graduation or strength characterist
soils acre
soils, so ,ics
may be thoroughly mixed with other soils to provide sa-is-
factory fill material, but only with the explicit consent of
the soil engineer.
PLACING AND CMPACTION OF FILL:
Approved material shall be placed in areas prepared to
receive fill in layers not to exceed six inches Fn compacted
thickness. Each layer shall have a uniform moisture content
in the range that will allow the compaction effort to be
efficiently applied to achieve the specified degree of
compaction to a minimum specified density with adequately
sized equipment, either specifically designed for soil
compaction or of proven reliability. The minimum degree of
compaction to be achieved is specified in either the special
provisions or the recomllendations contained in the prelimin-
ary soil investigation report.
Field tests and inspection to check the degree of compaction
of the fill will be taken by the soil engineer or his
representative. The location and frequency of the tests
shall be at the soil engineer's discretion. In general, the
density tests will be made at an interval not exc:eeding two
feet in vertical rise and/o.r 500 cubic yards of embankment.
SEASON LIMITS:
. Fill shall not be placed du!-ing unf.ivorab!.e weather con-
ditions. When work is inter:upted by heavy rain, filling
opercitions shall not bc resumed until the proper moisture
content and density of the :-ill has been achieved. Damage
resul~ting from weather shal! be repaired before acceptance
of wrjrk.
UNFORSEEN CONDITION:
In the event that conditions are encountered during the site
preparation and construction that were not encountered
during the preliminary soil investigation, San Dieguito
Engineering, Inc., assumes no responsibility for conditions .
encountered which differ from those coni.itions found and
described in the prelinimary soil investigation report.
SPECIAL PROVISIONS
The minimum degree of compaction of compaction to be ob- -
tained in compacting natural ground and in the compacted
fill shall be 90 percent of the maximum dry density obtained
in the laboratory, A.S.T.M. D-1557-70.
Detrimentally expansive soil is deEined as soil which will -
swell more than 3 percent of the original sample thickness.
The expansive potential is determined by allowing the mat-
erial, remolded to 90% of its maximum dry density, to swell
against a surcharge of 150 psf when brought into contact
with water. the expansion of the sample is determined by
measuring the swell from air-dry to saturated conditions.
Oversized fill material is defined as rocks or :lumps over -- --__-
six inches in diameter. At least 40 percent of the fill
soil sliall 1~s~ through a No, 4 U.S. Standard Sieve.
RECXMMENDAT IONS FOR FILLING
ON SLOPING GROUND --....A---
Toe Key I*+- n; 2 ft. Min. _,A
bu.E-Lru GrounQ ,* _
~- .,'y ", V-' -
Existing Ground Surface
/ --
/Zone Of LQO6e
/ ~' Surface Soil
CCnQaCted Pill
)~Horizontal Benches Into Firm Ground, 6 Feet ,Minimum
Toe Key - W:idth To Be' Deter]nir,ed by SOi1 k iginti.!r, But Not Less 'l'hari 10 k'ee t
SCHEMATIC ONLY
NOT TO SCALE
SAN tW~C;U.lTO E!!~ &‘. INC. PLATE A ..- ._-_^_-._., -___-_