HomeMy WebLinkAboutCT 73-36; El Camino Portals; Soil & Geologic Investigation; 1974-02-01,I
.. REPORT
to
SOMMERS BUILDING ENTERPRISES
La Mesa, California
on
SOIL AND GEOLOGIC INVESTIGATION
for
EL CAMINO PORTALS
Carlsbad, California
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s1010.5.108
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GEOCON, INCORPORATED .
San Diego, California
February i.974
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ENGINEERS AND GEOLOGISTS l CONSULTANTS IN THE APPLIED EARTH SCIENCES INCORPORATED
File No. D3-0177-SO1 February 1, 1974
Sommers Building Enterprises P.O. Box 2158 La Mesa, California 92041
Attention: Mr. Amos Sommers
Subject: El Camino Portals Carlsbad, California SOIL AND GEOLOGIC INVESTIGATION
Gentlemen:
In accordance with your authorization, we have performed a soil investi- gation on the subject project. The proposed project will consist of 146 single family one and two story wood frame residences. Grading will create cut slopes of up to 20 feet and fill slopes of up to 60 feet. The scope of our work included field drilling and sampling, laboratory testing, geologic studies and engineering analyses upon data obtained.
The enclosed report presents the findings of our investigation. It is our conclusion that, despite some areas of adverse soil and/or geologic conditions, the site may be utilized for the proposed development, provided the recommendations of this report are carefully followed.
Very truly yours, .
GEOCON, INCORPORATED I
James E. Likins, P.E.
sas
Copies: 8 to Sommers Building Enterprises
2 to Robert Young Engineering
7006 CONVOY COURT l SAN DIEGO, CALIFORNIA 92111 l PHONE (714) 292-5100
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File No. D3~0177-S01- February 1, 1974
SOIL INVESTIGATION
Purpose and Scope
The purpose of the soil and geologic investigation on the subject site
was to determine the surface and subsurface soil and'geblogic conditions
and, based upon the conditions encountered, provide recommendations for
development of the site into 146 one and two story wood frame residential
structures. Grading specifications and foundation design criteria which
would satisfy Public Agency requirements were to be included in the
report. To obtain the necessary information for the report, an extensive
i field and laboratory investigation was performed. Engineering analyses
were performed on the data obtained from the separate phases of the in-
1 vestigation and this report was prepared based upon the analyses.
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Location and Description of Site and Project
The site is located on a 52.5 acre parcel of land in Carlsbad, California,
located east of El Camino Real and south of the El Camino Mesa subdivision,
Units 3 and 6. The southerly boundary is the proposed easterly extension
of Tamarack Avenue. The western boundary is vacant land which may be
developed at a later date. As can be seen by referring to the enclosed
Figure 1 "Site Plan and Location of Test Borings" the parcel resembles
a north-south oriented rectangle being about 2800 feet long and 800 feet
wide. The site is vacant and supports a moderately heavy growth of wild
grass.
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Fixe No. D3-0177-Sbl February 1, 1974
Topographically the parcel consists of a north northwest south southeast
trending ridge, the crown of which runs down the approximate center
of the property. The high point of the site, at an approximate elevation
of 285 feet is in the north central portion of the site. The low point
of the site is at the southwest corner at an elevation of 70 feet. The
ridge generally runs downhill from north to south and slopes both to the
east and west from the crown. A drainage channel is pres'ent adjacent to
El Camino Real on the western boundary of the property. The side slopes
of the ridge are moderately steep, particularly on the eastern side of
the property. Drainage swales have been created in several areas by
the eroision forces of storm waters.
Development of the site will consist of lowering the elevation of the
ridge by cutting operations and raising the side slopes by filling to
create conventional single family residential lots. The maximum depths
of the cutting operations will be about 40 feet. However, the actual ex-
posed cut slopes will be relatively low, obtaining a maximum height of
about 20 feet. Fill slopes will have maximum vertical depths of about
50 feet. Maximum slope heights will be about 65 feet. These will occur
only in swale areas. Typical fill slopes heights will run about 30 feet.
The proposed slope ratios for cut and fill slopes are 2 horizontal to 1
vertical. conventional wood frame residential construction is proposed
for the one and two story residential structures. Concrete slab-on-grade
floor systems will be utilized.
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.le'.Fo. D3-0177-SO1 !bkua'rG 1, L1974
North
Scale 1" = 500'
@ Approximate location of test borings
El Camino Portals
Carlsbad, California
FIGURE N”- PAGE W
1 GEOCOM , IfKORPORATED 3 .
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Fiie No. D3-0177-SO1 February 1, 1974
The locations and descriptions contained herein are based upon a site
inspection by the Soil Engineer and upon a tentative map of the project
prepared by Robert Young Engineering.
Field Investigation
The field investigation was performed on December27., and 28, 1973, and
consisted of a site inspection by our soil engineer and the drilling of
12 test borings to depths varying from 11 to 41 feet below the existing
ground levels. The drilling was performed by a truck mounted drill rig
with continuous flight, six-inch diameter augers. As drilling.was advanced,
undisturbed soil samples were obtained by driving a 3 inch diameter'split
spoon sampler equipped with one-inch high brass rings into the undisturbed
'soil mass by dropping a 140 pound weight 30 inches. The samples obtained
were visually classified in accordance with the Unified Soil Classification
.System by the supenrising soil engineer and then sealed to be returned
$0 the laboratory for testing. Disturbed bulk samples were also obtained.
'Drawings 2 through 13 of Appendix A depict the soil types encountered and
ithe location of samples. I
iLaboratory Investigation
IIn the laboratory, the moisture density relationship of undisturbed
'samples was determined by weighing a known volume of soil before and after
joven drying. Expansion characteristics were determined from San Diego .
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File No. D3-0177-SO1 _ February 1, -1974
County standard swell tests. Strength tests were performed upon remolded
bulk samples. The tests were strain controlled direct shear tests. Speci::
mens to be tested were saturated and then sheared under varying normal
loads without appreciable drainage of the samples. Expansive potential
and classification were determined from the results of Atterberg Limits
!testing. The compaction characteristics were obtained from the results
iof the A.S.T.M. Compaction Test 41557-70 Method A. The settlement potential
tfor alluvial soils was determined by confined compression tests.
iAl1 laboratory test results are summarized in Tables I through IV of
;,Appendix A and in figures 14-16.
i ;Soil and Geologic Conditions
i jThe top of the ridge in the northern quarter of the site is capped by
up to 8 feet of Linda Vista Terrace deposits. In this area the Linda i yista Formation consists of light brown to reddish brown partially cemented
Flayey to silty sands and gravels. Underlying the Linda Vista Formation,
t . .
and exposed throughout the remainder of the site, is the E0cen.e De1 Mar
Formation of the La Jolla Group. In this area, the De1 Mar Formation
bonsists of claystone to sandy claystone interbedded with poorly indurated i 'medium to fine grained clayey sandstone. The bedding generally strikes
east-west and dips north at approximately 20 to 25";
fhe soil mantle on the site has been formed by in-place weathering of the
underlying formational material. 'The terrace soils consist of clayey
File No, D3-O177-Sbl February 1, 1974
to silty sands. The soils capping the De1 Mar Formation are generally
silty to clayey sands and silty to sandy clays. Because the geologic
formations are poorly indurated, they are susceptible to accelerated
erosion. Boring data indicate the erosional processes have deposited
soil in thicknesses of up to 6 to 8 feet in swales, particularly in the s
eastern slopes. Observations of the western slopes indicate similar
/ thicknesses. The De1 Mar Formation is relatively stable with respect to
I ~ landsliding in natural slopes. However, in the northwest portion of the
i I site (lots 52-61), there has been an accumulation of soil debris due to >
i the combined actions of creep, slopewash, and sloughing which can generally
I i be described as shallow landsliding. The reasons for the sloughing in
i 1. this area is probably due to bedding pla=orientation the contact between ! i the De1 Mar and Linda Vista Formations,and the erosional process. The b
/other areas of the site appear to be relatively free from such sloughing
i iof soil debris. Such soil debris will need to be removed and recompacted
i - jprior to placing fills in the area. t
There are no known active faults on this site. An unnamed fault was I noted approximately one-quarter mile south. of this site. The fault is
!presumed to be inactive. To date, no data has been presented in
pources available to us which indicates active faulting.in the area. The
'closest probably active fault system is the Rose Canyon Fault system
located about 14 miles ot the west. The active Elsinore Fault Zone lies
shout 35 to 40 miles to the northeast. The probable major earthquake
lazard would be shaking in the event of a significant earthquake on an
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File Noi'D3-0177-sol February 1, 1974
active fault system. According to the "Generalized Lithology and Earth-
quake Damage Potential Map", prepared by the CPO for San Diego County
(plate 1, 1972-1973), the property is in the middle of five damage
potential groups which range from greatest to least on the basis of
sub-surface lithology. the earthquake hazard for the site is therefore
not considered unusual for this area.
From a geologic standpoint several potential hazards are present which
will require attention during grading operations.
1. Soft slopewash deposits and sloughing debris should be removed
until cometent material is reached.
2. Most material on the site is considered expansive. '
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3. All materials possess a high erosion potential.
4. Cuts along the eastern flank of the ridge should not be
performed without additional exploration to verify bedding conditions
in that area. No such cutting is currently planned for this area. i -
The field drilling and laboratory testing program substantiate the
results of the geologic investigation. The soil and geologic formation
encountered generally possessed low to high expansive potential. Most :A'
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File No. D3-0177-Sbl February 1, 1974
material on the.site is considered to be expansive. The materials
possess good strength characteristics in the natural and recompacted
state. All materials encountered should be rippable with heavy grading
equipment. Slopewash deposits are compressible for depths of up to
8 feet. However, in most areas, the depth to competent material is on
the order of 2 to 3 feet. No ground water was encountered during our
investigation. It is therefore not expected to present problems during
site development unless grading occurs during or shortly after the rainy
season.
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File No. D3-0177-Sol February-l, 1974-
CONCLUSIONS AND RECOMMENDATIONS
General
1. The site may be utilized for the proposed development provided the
recommendations of this report are carefully followed. The undisturbed
native soils, properly compacted native soils or combinations thereof
should adequately support the proposed structures without detrimental
settlements.
2. Stength testing on the proposed fill soils and the Taylor Critical
Height slope stability analysis utilizing of Factor of Safety of 1.5
indicate allowable fill heights of 38 to 82 feet at slope ratios of 2
horizontal to 1 vertical.' For the majority of the site fill slope sta-
bility should not be critical,. In the areas of deeper fills, selective
grading may be required to place the higher strength soil in these areas.
3. Cut slopes at a 2 horizontal to 1 vertical ratio should be stable for
heights of up to 20 feet. However, geologic inspection of all cut slopes
will be required to ascertain if adverse bedding conditions are present.
If adverse bedding conditions are present, buttressing of cut slopes will 1
be required. <
4. The soil on the site varies in expansive potential from low to high.
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File No. D3-O177-SO1 February 1, 1974
Xt is unlikely that sufficient quantities of low expansion soil will be
present on the site to cap building pads and roadways. The bulk of the
low expansion material is at the upper elevations at the north end of
the site. A selective grading operation should be utilized which
retains as much low expansion material as possible for capping or for use
in deeper fills. Consideration should also be given to the use of lime
as an-additive to lower the expansive potential of building pads and to
increase the strength and pavement supporting characteristics of the on-
site materials.
5. Final foundation design recommendations will be presented upon COM-
pletion of grading operat!ons. A range of anticipated recommendations
is contained in this report.
Grading
6. All grading should be performed in accordance with the Recommended
Grading Specifications contained in, Appendix B.
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7. Native soil excavated from colluvial or slopewash areas, or from
formational deposits, are suitable for use as compacted fill, if free /
from organics or other deleterious material. All fill should be placed
at a minimum of 90% relative compaction based upon A.S.T.M. Compaction
Test Dl557-70 Method A. All fill must be placed at a moisture content
at least 2% above optimum moisture content. In the clayey soil,considerablc
effort will be necessary to obtain the desired moisture contents.
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File No-. -D3-0177-SO1 February 1, 1974
8. All areas to be graded should be stripped of all grass, brush and
other debris. The depth of stripping will depend upon weed growth
present at the time of grading. For estimating purposes, 0 to 2
inches may be assumed for the depth of stripping. Any material stripped
should not be used as compacted fill, but hauled from the site or stock-
piled for reuse as topsoil.
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9. Areas in swales or in slough zones should be over-excavated at the
direction of the soil engineer, until bedrock or firm alluvial soil is
encountered. ‘The material excavated may be re-used as compacted fill.
The depths of the over excavation will vary from 2 to 8 feet. Primary
areas to be overexcavated is the slough ‘zone at the toe of fill slopes
along lots 50-61, the swales to the rear of lots 140, 132, 122, 117, 114,
and lot 16, and the rather broad colluvial/ alluvial deposit along the
rear of lots 4-8.
10. The toes of all fill slopes should then be given a base key-as described
in the‘grading specifications and Figure 16. The bottom of the key should
be scarified to a depth of 8 inches, moisture conditioned and recompacted
to 90% minimum relative compaction based upon A.S.T.M. Compaction Test
D1557-70 Method A.
11. Fill, either from the aforemention overexcavations or from on-site
cutting operations, may then be placed in compacted layers. All fill
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placed must be at least 2% above optimum moisture content and be compacted
to at least 90% relative compaction. If possible, excavations from
claystone areas should not be placed in the deeper fill areas. As fills
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proceed up slope they should be properly benched and keyed to the original
ground.
P 12. During cutting operations, non-expansive soil' should be stockpiled
for capping building pads and/or street sections.
13. Building pads which contain a cut-fill daylight line should be over-
excavated by two feet. Pads entirely in cut sections should be scarified
8 inches, moisture conditioned and recompacted to at least 90% relative
compaction. If sufficient on-'site non-expansive material is available,
cut pads which possess expansive material should be overexcavated 2 feet
and be capped with non-expansive soil.
14. Geologic inspection of all cuts should be performed to determine
if adverse bedding conditions exist. This is particuilarly important
in the deeper cut zones of lots 112 and 113.
15. The top 2 feet of fill in building pads should consist of non-
expansive soil if possible. If not possible consideration should be
given to lime treatment or other forms of stabilization to reduce expansive f
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potential.
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File No.-D3-0177-SO1 February 1, 1974
Foundations
16. Conventional strip footings may be utilized for foundation construction
An allowable bearing capacity of 2000 p.s.f. is recommended for dead plus
live loads. The bearing capacity may be increased by one third for short
time loading. The minimum footing width should be 12 inches. If non-
expansive or lime treated soils cap the building pads the recommended.
footing depths
footing depths
of expansion.
are a minimum of 12 inches. If expansive soil is present
will be either 18 or 24 inches depending upon the degree
17. Minimum footing reinforcement should be one f4 bar at the top and bot-
tom of all footings. If sufficiently expansive soil is present, the size
of the bars will be increased, or else 2 #4 bars top and bottom will be
required. .
18. If sufficiently expansive soil is present , presoaking of the pad
area will be required prior to foating excavation. . . . -
Slabs-on-Grade
19. Minimum slab reinforcement should consist of 6" x 6" No10 xNo 10
wire mesh located at the center of the slab. The slab should be underlain
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File No. D3-0177~501 February 1, 1974
by 1 to 2 inches of sand over impervious membrane..
20. If sufficiently expansive soil is present, the slab reinforcement
should be increased to No 6 x No 6 wire and the bedding under the slab
increased to 6 inches. In addition, presoaking of the slab will be
required.
Drainage and Maintenance
21 Good drainage is imperative, to control both expansiveness and
erosion. All pads must have drainage swales which direct storm and
irrigation water away from the structures and into street gutters or
other drainage facilities. No water should be allowed to pond adjacent
to footings.
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22. If downdrains are used, they should discharge into splashblocks
and into the aforementioned swales.
23. ’ Effective maintenance of slopes is essential. In our experience,
a well controlled planting and irrigation system is superior to a bench
and drain design.
24. No storm or irrigation water should be allowed to discharge over
cut or fill slopes.
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File No. D3-0177-SO1 February 1, 1974
25. Siltation basins should be provided if the rainy season occurs
during grading or prior to the establishment of ground cover on
slopes.
26. The proposed unlined drainage-channel along El Camino Real
must be carefully maintained. If uncontrolled, its erosional process
will undercut the natural and proposed fill slopes and create sig-
nificant stability problems.
27. In claystone cut slopes, shall "popout" slope failures
may occur due to the elimination of overburden stresses. Those
will particularly occur.during wet seasons or at the time of heavy
irrigation. Mainenance and/or replanting of these areas is essential
. to control excessive slope debris. . .
Grading Plan Review
28. The soil engineer and engineering geologist should review the
final grading plans to verify its compliance with this report and
with U,B.C. Chpater 70 as required by the State of California
Division of Real Estate.
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I File No. D3-0177-SO1 February 1, 1974
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. The recommendations of this report pertain only to the site
investigated and are based upon the assumption that the soil condi-
tions do not deviate from those disclosed in the borings. If any
variations or undesirable conditions are encountered during construc-
tion, or if the proposed construction will differ from that planned
at the present time, Geocon, Incorporated should be notified so
that supplemental recommendations can be given.
2. This report is issued with the understanding that it is the
responsibility of the owner, or of his representative, to ensure
that the information and recommendations contained herein are brought .
to the attention of the Architect and Engineer for the project and
incorporated into the plans, and that the necessary steps are taken
to see that the Contractor and Subcontractors carry out 'such recom-
.mendations in the field.
3. The findings of this report are valid as of the present date.
However, changes in the condition of a property can occur with the
passage of time, whether they be due to natural processes, or the
wxks of man on this or adjacent properties. In addition, changes
in applicable or appropriate standards occur, whether they result
from legislation or the bro?dening of knowledge. Accordingly, the
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File No. D3--0177-SO1 Febniary 1, 1974
findings of this report may be invalidated, wholly or partially,
by changes outside of our control. Therefore, this report is sub-
ject to review and should not be relied upon after a'period of one
year.
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Appendix A
Summary of Laboratory Test Results
Logs of Test Borings
Laboratory Compaction Tests
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Fi'le Nd. D3-0177-SO1 -. February 1, 1974
TABLE I
Summary of In-Place Moisture-Density and Direct.Shear Test Results
Sample Depth No. . ft.
::;
;:;
;:;
2-3 2-4 *,
3-l
I:;
4-3
2
1:
z
-1:
4-9 Bulk Sample
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1:
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5-3 5-4
6-l
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7-l
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7-2* 7-3 7-4
I 8-l
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2
1x.
S-10'
35-E!
4 S-8*
1:
14
Angie of -
Dry Moisture Unit Shear Density Content. Cohesion Resistance p.c.f. % p.s.f. degrees *
. 114.9 5.6 117.1 8.4 . 115.9 14.9 132.5 8.7
113.9 9.4 109.6 181*; I
111.8 112.9 11:o
-118.4 - 7.6 Disturbed' Sample 115.8 12.4
111.5 .19.2 116.2 16.1
114.6 16.0
Lost Sample
Bulk Sample 96.4 18.1 79.8 19.5 600 10
119.8 8.8 " 116.4 490 29 124.7 69:: 107.1, 21.6
122.2 10.4'
I * Indicates sample recompacted to 90% relative compaction at optimum moisture content
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File No. D3-0177-SO1 Febkuary' 1, 1974 .
TABLE II
Summary of Laboratory Atterberg Limits Test Results
Atterberg Limits
Liquid Plasticity Sample - Depth Description Limit Index No. Ft. % (P.I.)
5-2 4 Gray Silty CLAY (CH) 62 35
6-2 35-40 Gray Silty CLAY (CH) 86 47 e
6-4 41 Gray Silty CLAY (CH) 86 62
7-& 4-8 Gray Clayey SAND (SP) 33 10
7-4 14 Gray Sandy CLAY (CH-CL) 63 37
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TABLE III
Summary of Laboratory Expansion Test Results
Moisture Content Expansion (+) Before After OR Test Test Dry Settlement (-> Sample Description Depth Density Surcharge No. ft. % % p.c.f. % p.s..f.
6-2 Gray Sil.ty / &A
CLAY (CH) 35-40 18.1 26.2 96.4 -i-25.0 150
7-2 Gray Clayey SAND (W-SC) 4-8 9.7 14.3 107.1 + 0.5 150 .
Samples were recompacted to 90% relative compaction at optimum moisture
content in 1" high x 2.375" diameter brass rings. The samples were
surcharged at 150 p.s.f. then inundated. The resulting swell was measured with a dial micrometer.
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Sample No.
6-2
7-2
TABLE Iv
Summary of Laboratory Compaction Test Results
A.S.T.M. 01557-70
Depth Description Max. Dry Density Optimum Moisture Ft. p.c.f. % dry wt.
35-40 Gray Silty CLAY (CH) 107.1 18.1
4-8 Gray Clayey SAND (SC) 129.3 9.7
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LESCRlPllON
slightly moist,
r-igure z - Log of Test Boring No. 1
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File No. D3-017Z-SO1 February 1, 1974
DESCRIPTION
moderately dense
SANDSTONE, hard,
Figure 5 - Log of Test Boring No. 2
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I 0
I i i 1 1 ia F 1 i %
r File No. D3-0177-SO1
February 1, 1974
ml.
IN
EET
0
2
4
6
8
LO
12
14
16
18
%th+PLE
NO.
3-1
LOG 8
XATION
OF
SAMPLE
,.. B 7 l -- . .-.
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DESCRIPTION
Gray brown Sandy CLAY, slightly moist, stiff (CL)
Gray tan Clayey SANDSTONE, fine grained, moist, dense
Gray sandy CLAYSTONE with SAND- STONE lensing moist to slightly moist, dense
Boring terminated at 18 .feet
Figure 4 - Log of Test Boring No. I
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IN-PLACE
DRY
DENSITY
pet.
Bulk
MOISTURE
CONTENT
To dry l i.
Sample
File No. D3-0177-SO1
February 1, 1974
DESCRIPTION
Gray Clayey to Silty fine
SANDSTONE with occasional CLAYSTONE l&sing
r'lgure 3 ,-) Log of: Test Boring No. 4
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ed
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File No. D3-0171-So1
February 1, 1974
DESCRIPTION
CLAY, moist, stiff
Light gray to tan Silty CLAYSTONE, moist, hard, occasional sand
Figure b - Log 02 Test Boring No. 5
File No. D3-0177-SO1 February 1, 1974
OEXRIPTION
Brown/gray Sandy CLAY, moist, stif
Light brown silty CLAYSTONE with SANDSTONE lensing, moist, hard
16 foot break in log
increasing clay content w/ depth
- Figure / - Log or Test Boring No. 6
. 28
Figure 8 - Log of Test Boring No. 7
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File No. D3-0177-SO1 February-l., 1974 __
oEsCRlPTlON
rown Sandy CLAY, moist
Light tan to gray Clayey SAND to Silty SAND slightly moist, dense
Boring terminated at 18 feet
File No. D3-0177-SO1
February 1,,1974
IN- PLACE
‘T ii SAMPLE LOG B %7.St,OtlO” DESCRIPTION
UXXTION Rel~rtmca DRY MJSTURE N NO. OF DENSITY CONTENl ‘ET SAMPLE Blas/fl pd. ah dry wt.
Dark brown Silty CLAY, moist, stiff
Light brown to tan Silty CLAY- STONE with minor SILTSTONE and SANDSTONE lensing
Boring terminated at 23 feet
Figure 9 - Log of Test Boring No. 8-,/,
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File No. D3-017j-SO1 February' 1, 1974 -
DESCRIPTION
Dark brown Silty CLAY, moist stiff (CH-CL)
Figure IU - Log ot Test Boring No. 9
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File No. D3-017j-SO1 February 1, 1974
IN- PLACE
PTH SllMPLE LOG 8 +lemtmn DESCRIPTION
IN NO. LLXATION Re111tmca DRY MOISTURE
EET OF
SAMPLE Sloln/ft DENSITY CONTENT
p.cf. %dv wt.
Dark brown Sandy CLAY, moist,
Figure ll- Log of Test Boring No. 10
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February 1, 1974
DESCRIPTION
Dark brown Sandy CLAY, moist, stiff
Boring.terminated at 13 feet
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- Figure 12 - Log of Test Boring No. 11
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February 1, 1974
DESCRIPTION
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Boring terminated at 13 feet-
Figure 13 - Log of Test Boring No. 12
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File No. D3-0177-SO1
' I Februarv 1. 1974
16 18 20 22
Moisture Content - (% of Dry Weight)
Samp'e' 6-2 Depth 35-40'
Description : Gray Silty CLAY (CH)
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Laboratory Test Procedure :A.S.T.M. ~1557-70 Method A
Maximlim Dry Density : 107.1 p.c. f,
Optimum Moisture Content : 18.1%
Figure 14 - Labbratory Compaction Test
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.kile No. D3-0177-SO1
FPhml=1rv 1. 1974
h u: 130
3 ri V 3% .- v) 125
s D
Moisture Content - (% of Dry Weight)
Sample : 7-2 Depth 4-9'
Description :Gray brown Clayey SAND (SC-SP)
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Laboratory Test Procedure : A.S.T.M. D1557-70 Method A
Moximirm Dry Density : 129.3 p.c.f.
Optimum Moisture Content : 9.7%
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Figure 15 - Laboratory Compaction Test
File No. D3-0177-501
EL CAMINO PORTALS
Carlsbad, California
FIGURE NO- PAGE N”
16 GEOCOM 9 INCORPORATED 37 .
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Appendix B
Recommended Grading Specifications
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File No. D3-O177-SO1 February 1, 1974
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RECOMMENDED GRADING SPECIFICATIONS
for
EL CAMINO PORTALS
Carlsbad, California
1.1 General Description
1.11 These specifications have been prepared for grading and site development of El Camino Portals which is located east of El Camino Real and south of Trieste Street in Carlsbad, California. Geocon, Incorporated, hereinafter described as the Soil Engineer, should be consulted prior to any site work connected with site development to ensure compliance with these specifications. These specifications shall only be used in conjunction with the'soil report of which they are a part.
1.12 This item shall consist of all clearing tind grubbing, prepar- ation of land to be filled, filling of the land, spreading, compac- tion and control of the fill, and all subsidiary work necessary to complete the grading of the filled areas to conform with the lines, grades and slopes as shown on the accepted plans.
1.13 In the event that any unusual conditions not covered by the special provisions are encountered during grading operations, the Soil Engineer shall be immediately notified for direction. The Soil Engineer shall test,and observe all grading operations.
2.1 Tests
2.11 The standard test used to define maximum density of all compac- tion work shall be the A.S.T.M. Test Procedure No. 01557-70. All
0 densities shall be expressed as a relative compaction in terms of the maximum density obtained in the laboratory by the foregoing standard procedure.
3.1 Clearing, Grubbing and Preparing Areas to Be Filled
3.11 Any trees not utilized in landscaping, structures, weeds, and other rubbish shall be removed, piled or otherwise disposed of so as to leave the areas that have been disturbed with a neat and finished appearance, free from unsightly debris,
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File No. D3-Ol77-Sol February 1, 1974
3.12 Any septic tanks, if encountered, and debris must be removed from the site prior to any building, grading .or fill operations. Septic tanks, including all connecting drain fields and other lines, must be totally removed and the resulting depressions properly recon- structed and filled to the complete satisfaction of the supervising Soil Engineer.
3.13 All water wells on the site shall be capped according to the re- quirements of the San Diego County Health Department, The strength of the cap shall be at least equal to the adjacent soil. The final elevation of the top of the well casing must be a minimum of 36 inches below any adjacent grade prior to any grading of fill operations.
3.14 All buried tanks, if encountered, must be totally removed and the resulting depressions properly reconstructed and filled to the complete satisfaction of the supervising Soil Engineer.
3.15 All vegetable matter, and soil designated as unsuitable by the Soil Engineer shall be removed under the direction of the Soil Engineer. The theri exposed surface shall then be plowed or scarified to a depth of at least 8 inches and until the surface is free from ruts, hummocks or other uneven features which would tend to prevent uniform compaction by the equipment to be used.
3.16 The original ground upon which the fill is to be placed shall be plowed or scarified deeply and where the slope ratio of the origi- nal ground is steeper than 6 horizontal to 1 vertical, the bank shall be stepped or benched. At the toes of the major fills and on the sideslope fills, . report, the base key shall be, as described elsewhere in this at least 10 feet, in width, cut at least 3 feet into the undis- turbed or native soil, of not less than 2%. and sloped back into the hillside at a gradient Subsequent keys should.be cut into the hillside as the fill is brought up the slope. The construction of subsequent keying operations shall be determined by the Soil Engineer during grading operations. Ground slopes which are flatter than 6 to 1 shall be benched when considered necessary by the Soil Engineer.
3.17 After the foundation for the fill has been cleared, plowed or scarified, it shall be disced or bladed until it is uniform and free from large clods, water or aerating, brought to the proper moisture content by adding
90%. and compacted to relative density of not less than
4.1 Materials
4.11 Native soil, free of organic material and undesirable deleterious
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File No. D3-0;77-SO1
February 1, 1974
material may be used as fill. Native soil which is expansive shall not be placed on the top two feet of building pads without the approval of the Soil Engineer.
4.12 The materials for fill shall be approved by the Soil Engineer before commencement of grading operations. Any imported material must be approved for use before being brought to the site. The mater-
. ials used shall be free from vegetable matter and other deleterious material and be non-expansive. Expansive soil is defined as soil which expands more than 3.0 percent when saturated at 90% relative . compaction and optimum moisture content under a-surcharge of 150 p.s.f.
571 Placing, Spreading and Compacting Fill Material ':
5.11 The selected fill material shall-be placed in layers which, when compacted, shall allow adequate bonding and compaction. Each layer shall be spread evenly and shall be thoroughly blade mixed during,the spreading to ensure uniformity of material in each layer.
5.12 When the moisture content of the fill material is below that specified by the Soil Engineer, water shall be added until the mois- ture content is as specified to assure thorough bonding during the compaction process. When the moisture content of the fill material is above that specified by the Soil Engineer, the fill material shall be aerated by blading or-other satisfactory methods until the mois- . ture content is as specified. All material will be placed at a moisture content at least two percentage points above optimum moisture content.
5.13 After each layer h&s been placed, mixed and spread evenly, it shall be thoroughly compacted to a relative compaction of not less than 90%.
&' 5.14 When fill material includes rock, no rocks will be allowed to nest and all voids must be carefully filled with small stones or earth and-properly compacted. No rocks larger than 4 inches in dia- meter will be permitted in the fill.
'. 5.15 Compaction shall be by sheepsfoot rollers, multiple-wheel pneumatic-tired rollers or other types of acceptable compacting rollers. Rollers shall be of such design that they will be able to ' compact the fill to the specified moisture content range. Rolling of each layer shall be continuous over its entire area and untfl the required density has been obtained.
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File No. D3-OI77-SO1 February 1, 1974
5.16 Field density tests shall be made by the Soil Engineer. Where sheepsfoot rollers are used the soil may be disturbed to a depth of several inches. Density tests shall be taken in compacted
material below the disturbed surface. When these tests indicate that the density of any layerof fill or portion thereof'is below the required 90% density, the particular layer or portion shall be reworked until the required density has been obtained. "
5.17 The fill operation shall be continued in compacted layers, as specified above, until the fill has been brought to the finished slopes and graded as shown on the accepted plans.
5.18 Fill slopes shall be compacted by means of shee sfoot rollers or other suitable equipment. Compaction operations s ii all be contin- ued until the slopes are stable. .
5.19 All earthmoving and working operations shall be controlled to .prevent water from running into excavated areas. All water shall be promptly removed and the site.kept dry.
6.1 Supervision
6.11 Supervision by the Soil Engineer shall be made during the fill and compaction operations so that he can certify that the fill was made in accordance with the accepted specifications.
7.1 Seasonal Limits'
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7.il No fill material shall be placed, spread or rolled while it is at an unsuitable high moisture content or during unfavorable weather conditions. When the work is interrupted by heavy rain, fill opera- tions shall not be resumed until field tests by the Soil Engineer indicate that the moisture content and density of fill are a's pre- viously specified.
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