HomeMy WebLinkAboutPE 2.85.31; POINSETTIA VILLAGE; GEOTECHNICAL INVESTIGATION; 1985-06-06•
ENGINEERING
•
- REPORT OF GEOTECHNICAL INVESTIGATION. • LOTS -3 AND 6-8, MAP 10870 *
BRUCE ROAD AND PARK DRIVE
CARLSBAD, CALIFORNIA
*
PREPARED FOR:
*
B. A. Worthing
PortOffice Box 1041
Carlsbad, California
* PREPARED BY: -
*Southern California Soil -1 Testing, Inc.
Post Office Box 20627
6280 Riverdale Street
S San Diego, California 92120
SOUTHERN CALIFORNIA SOIL AND TESTIN'G, INC..
6280 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 280-4321 P.O. BOX 20627 SAN DIEGO, CALIF. 92120
74-831 V E L I E WAY PALM DESERT, CALIF. 92260 • T E L E 346-1078
678 ENTERPRISE ST. ESCONOIDO, CALIF. 92025 • T E L E 746-4544
June 6, 1985
B. A. Worthing
Post Office Box. 1041 SCS&T 8521118
Carlsbad, California 92008 . Report. No. 1
SUBJECT: Report of Geotechnical Investigation, Lots 3 and 6-8. Map
10870, Bruce Road and Park Drive, Carlsbad, California.
Gentlemen:.
In, accordance with your, request we have completed ageotechnical
investigation for the proposed project. We are presenting herewith our
findings and recommendations.
The findings of this study indicate that the site is suitable for the
proposed development provided the recommendations presented in the attached
report are complied with.
If you have any questions after reviewing the findings and recommendations
contained in the attached report, please do not hesitate to contact this
office. This opportunity to be of professional service is sincerely
appreciated.
Respectfully submitted,
SOUTHERN CALIFORNIA SOIL & TESTING, INC.
J. 4/(
Jptn R. High, C.E.G. 1237 Fobrt-R.'Russefl, R.C.'#32142
RRR:JRH:nr
cc: (5) Submitted
(1) .SCS&T, Escondido
S
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
TABLE OF CONTENTS
PAGE
Introduction and Project Description ...................................... 1
Project Scope .............. . ............................................... 1
Findings...................................................................2
SiteDescription .................................................... ..2
GeneralGeology and Subsurface Conditions ............................. 3
Geologic Setting and Soil Description.............................3
TectonicSetting .................................................. 3
GeologicHazards..................................................4
Groundwater.................................................. .....5
Recommendations and Conclusions ...........................................5
SitePreparation ....................................................... 5
General............................................................5
SurfaceDrainage .................................................. 6
Earthwork....... ................................................... 6
Foundations............................. . ................................... 6
General...............................................................6
Settlement Characteristics.... .................................... 6
ExpansiveCharacteristics .............. . ........................... .6
RetainingWalls ......................................... . .................. 7
General...........................................................7
Backfill..........................................................7
BearingPressure ........... . ............................. . ....... 7
PassivePressure ................................................. .7
ActivePressure ........ .. ........ . ....................... .. ...... 7
Factorof Safety...................................................8
Limitations, ................. . ......... . ............................ . ..... 8
Review, Observation and Testing ............. . ................ . ........ ...8
Uniformity of Conditions ..............................................8
Changein Scope ........................................................ g
TimeLimitations.. ................................ . ............ . ...... 9
ProfessionalStandard .......... . ............ ............................ 9
Client's Responsibility ............... . ............................... 10
FieldExplorations ................... . ......................... . .......... 10
La.boratory Testing ......................................................... 10
ATTACHMENTS." '
PLATES
Plate 1, Plot Plan
Plate 2 Subsurface Exploration 'Legend
Plate 3-7 Trench Logs
Plate 8 Direct Shear Test Results
Maximum Density and Optimum Moisture Content
APPENDIX
Recommended Grading Specirication and Special Provisions
2 ' "
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
6280 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 2804321 • P.O. 80X 20627 SAN DIEGO, CALIF. 92120
74 -831 yELlS WAY PALM DESERT, CALIF. 92260 • T E L E 346-1070
6 7 B ENTERPRISE ST. ESCONOIDO, CALIF. 92025 T E L E 746-4544
GEOTECHNICAL INVESTIGATION
LOTS-3 -AND 6-8, MAP 10870
BRUCE RAUD AND PARK DRIVE
CARLSBAD, CALIFORNIA
INTRODUCTION AND PROJECT DESCRIPTION
This report presents the results of our geotechnical investigation for four
proposed residences which are to be located near the intersection of Bruce
Road Park Drive in the City of Carlsbad.
It is-our understanding that. some additional grading is proposed'to develop
these sites but the maximum. cuts and. fills planned are generally in. the
order of 10 feet or less in height. The site configuration and exploration.
locations are shown on Plate No. 1.
.
.
PROJECT SCOPE
This investigation consisted of: surface reconnaissance; subsurface
explorations; obtaining representative 'disturbed.. and undisturbed samples;
laboratory testing; analysis of the field and, laboratory data; research of
available geological literature pertaining to the site; and preparation of
this report. Specifically, the intent of this analysis was to:
a) Explore the subsurface'conditionsto the depths influenced by -the
proposed construction. . • •'
SOUTHERN CALIFORNIA SOIL AN.D TESTING, INC.
SCS&T 8521118 June 6, 1985 Page 2
Evaluate, by laboratory tests, the pertinent engineering
properties of the various strata which will influence the
development, including their bearing capacities, expansive
characteristics and settlement potential..
Define the general geology of the site including possible.,
geologic hazards which could have an effect on the site
development.
Develop soil engineering criteria for site grading.
Determine potential construction difficulties and provide
recommendations concerning these problems.
Recommend an appropriate foundation: system for the type of
structures anticipated and develop soil engineering design
criteria for the recommended foundation design.
FINDINGS
SITE DESCRIPTION
The project site consists of four lots within an existing subdivision east
of the intersection of Bruce Road and Park Drive in Carlsbad, California.
Lot 3 is located on a west. to east trending ridge with a level pad on the
upper eastern portion of the lot which has been cut into the ridge.. This
site slopes steeply to the northwest, west and southwest with elevations
ranging from approximately 50 feet to 90 feet (MSL). These -slopes are in a
natural condition and vegetation consists of heavy growth of native brush,
plants and grasses. Lots6, 7, and 8 consist of relatively level cut and
fill pads bounded by approximately 4 feet to 30 feet high moderately steep,.
cut and fill slopes. Fill on these slopes ranges up to 7 feet high with a.
slope ratio on the order of approximately 2:1. (horizontal to vertical).
Elevations on these lots range from 30 feet to 100 feet (MSL).
SCS&T 8521118 June 6, 1985 Page 3
GENERAL GEOLOGY AND SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the
Coastal Plains Physiographic Province of San Diego County 'and is underlain
by materials of sedimentary origin and some artifical fill. Lot 3 has been
cut into the Eocene Santiago Formation and associated topsoil which
consists of tan, humid, dense, silty sandstone and up to 1 foot of brown,
dry., loose silty sand respectively. Soil conditions as encountered in our
explorations on Lots 6, 7 and 8 were approximately 3 to 7 feet. of
artificial fill consisting of brown to dark gray brown,. humid to moist,
loose to medium dense silty sand. The fill was generally underlain by a
minimum of 4 feet of alluvium which consist of gray brown to dark' gray
brown, moist, medium dense silty sand. On Lot 8 this alluvium was
underlain by a minimum of 2 feet of light tan, moist, medium dense very
friable sand. On the lower northwest pad area of Lot 7, three feet of
artifical fill was underlain by in excess of 7 feet of dark brown to gray
brown alluvium which was moist, medium dense, clayey sand.
TECTONIC SETTING: No evidence, of faulting was noted during our surface
reconnaissance or in our exploratory trenches. A. review of available
geologic literature reveals the presence of numerous minor northeast
trending faults in the Carlsbad vicinity of the site that are presently
classified as .inactive. The project site is located approximately 6 miles
.east of the Rose Canyon Fault Zone. The Rose Canyon Fault Zone. is a series
of northwest trending faults of Quaternary age that is currently classified
as potentially active, rather than active according to the criteria of the
California Division of Mines and Geology. This classification is based on
the lack of the conclusive evidence to verify Holocene movement along this
fault zone.
It should be recognized that much of Southern California is characterized
by major, active fault zones that could possibly affect the subject site.
The neanest of these are the Elsinore Fault Zone, located approximately 24
miles to the northeast.
0
0
SCS&T 8521118 June 6, 1985 Page 4
GEOLOGIC HAZARDS
The subject site can be considered to be relatively free of geologic
hazards. Potential hazards such as tusnamis, seiches, liquefaction, or
landsliding should be considered to be negligible or nonexistent.
The most likely major geologic hazard to affect the site is grouhdshaking
'as a result of movement along one of the major active fault zones mentioned
previously. The maximum bedrock accelerations that would be attributed to
a maximum probable earthquake occurring along the nearest portion of
selected fault zones that could, affect the site are summarized in the
following table.
TABLE
Maximum Probable Maximum Bedrock
Fault Zone Classification Distance .Earthquake Acceleration
Rose Canyon Potentially 6 miles 6.0 magnitude 0.35g
Active
Elsinore
,
Active 24 miles 73 magnitude 0.239
Based on •the current fault zone classification, and the maximum bedrock
accelerations capable of developing, it is recommended that the Coronado
Banks, El.sinore or San Clemente Fault Zones be considered the design
earthquake source for the subject development. -
Although ,a maximum probable earthquake along the La Nacion and/or Rose
Canyon Fault Zones could conceivably produce ground motions considerably
stronger than those that would be attributed to the major, active fault
zones, it is our opinion that, due to the current classification of these
local ,fault zones as potentially active rather than active, they should not
be used as the design earthquake soure for this project.
fl
SCS&T 8521118 June 6, 1985 Page 5
Construction in accordance with the minimum standards of the Uniform
Building Code and the governing agencies should minimize potential damage
due to groundshaking.
GROUNDWATER: No groundwater was encountered during our subsurface
xploration and we do not. anticipate any major groundwater related. exploration.*
problems, either during or after construction. However, it should be
recognized that minor groundwater seepage problems may occur after
developement of a site even where none were present before development.
These are usually minor phenomena and are often the result of an alteration
of the permeability charcteristics of thesoil, an alteration in drainage .
patterns and an increase in irrigation water. Based on the permeability
characteristics of the soil and anticipated usage of the development, it is
our opinion that. any seepage problems which may, occur will be minor in
extent. It is further our opinion that these problems can be most
effectively corrected on an individual basis if and when they develop.
RECOMMENDATIONS -AND CONCLUSIONS
SITE PREPARATION
GENERAL: We recommend that the existing fill and loose native soils be
removed to firm natural ground and be, stockpiled for future use. Firm
natural gournd is defined as native soil which possesses an in-situ density
equal to or greater 85%-of its maximum dry density. The soils exposed at
the base of these excavations should then be scarified 12 inches, be
moisture treated to at least. 2% ov.er optimum and densified to a minimum of
n 90% relative compaction. The stockpiled soils may then be replaced in
eight inch lifts, moisture conditioned and compacted as indicated above.
The horizontal limits of these recommendations should include the area
within a perimeter of 10. feet outside of each proposed structure and all
areas to receive additional fill and all slopes. Based on the findings of
this study, it is anticipated that. the maximum depth. of removal and
recompaction will be on the order of seven feet.
S
SCS&T 8521118 June 6, 1985 Page 6
SURFACE DRAINAGE: We recommend that all surface drainage be directed
away from the proposed structures and that ponding of water not be allowed
adjacent to the building foundations. It is further recommended that.
drainage not be allowed to flow over the top of slopes.
S
EARTHWORK: All earthwork and grading contemplated for site preparation
should be accomplished in accordance with the attached Recommended Grading
Specifications and Special Provisions. All special site preparation
recommendations presented in the sections above will supersede those in the
standard Recommended Grading Specifications. All embankments, structural
fill and fill should be compacted to at least 90% relative compaction at or
slightly over optimum moisture content. Utility, trench backfill within,
five feet of the proposed structures and beneath asphalt pavements should
be compacted to a minimum of 90% of i.ts maximum dry density. The maximum
dry density of each soil type should be determined in accordance with
A.S.T.M. Test Method D-1557-78, Method A or C.
n
FOUNDATIONS
GENERAL: It is our opinion that the proposed building may be supported
by shallow spread footings. All footings should be founded at least 12 or
18. inches below lowest adjacent finished grade for one or two story
structures, respectively. All footings should possess a minimum, width of
12 inches. An allowable soil bearing pressure of 2900 psf may be used for
foundation design. We further recommend that all continuous footings be
reinforced with at least one No. 4 bar top and bottom.
SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential
settlements for the proposed structure may be considered to be within
tolerable limit's provided the recommendations presented in -this report are
followed.
EXPANSIVE CHARACTERISTICS: The prevailing foundation soils were found to
.be nonderti mental ly expansive and will not require special consideration
and/or design.
U
0
SCS&T 8521118 June 6, 1985 Page 7
RETAINING WALLS
GENERAL: It is our understanding that the retaining walls planned for
the site will be of masonry construction and that they will have a maximum
hei'ght on the order of 6 feet. All walls should have adequate weep holes
or a subdrain system to prevent a building of hydrostatic pressure behind
the wall.
0
BACKFILL: All backfill soils should be compacted 'to at least 90%
relative compaction. Expansive or clayey soils should not be used for
backfill material. The wall should not be backfilled until the masonry has
reached an adequate strength.
BEARING PRESSURE: The foundation for the proposed walls may consist of
spread footings founded in the native, soils or compacted fill. Footings
should extend through any loose topsoils and fill or the topsoils and fill
should be removed and be replaced as a compacted fill. Footings may be
designed for an allowable bearing pressure as previously recommended.
PASSIVE PRESSURE: The passive pressure for the prevailing soil
conditions may be considered to be 350 pounds. per square foot per foot of
depth'. This pressure may be increased one-third for seismic loading. The
coefficient ,of friction' for' concrete to soil may be assumed to be 0.55 for'
the resistance to lateral movement. When combining frictional and passive
resistance, the latter should be reduced by one-third.
ACTIVE PRESSURE: The active soil pressure for the design of earth
retaining structures with level backfills may be assumed to be equivalent
to the pressure of a fluid weighing 35 pounds per cubic foot for walls.free
to move at the 'top (unrestrained walls). For a 2:1 backfill
condition, this design pressure should be increased to 55 pcf. These
pressures do not consider any surcharge other than the sloping backfill.
'Ifany are anticipated this office should be contacted for the necessary
increase in soil pressure. '
[1
SCS&T 8521118 June 6, 1985 Page 8
40
FACTOR OF SAFETY: The above values, with the exception of the allowable
soil bearing pressure, do not include a factor of safety. Appropriate
factors of safety should be incorporated into the design to prevent the
walls from overturning and sliding.
LIMITATIONS
REVIEW, OBSERVATION AND TESTING
The recommendations presented in this report are contingent upon our review
of final plans and specifications. The 'soil engineer and engineering
geolgist should review and verify the compliance of the final grading plan
with this report and with Chapter 70 of the Uniform Building Code.
It is recommended that Southern California Soil & Testing, Inc. be retained
-to provide continuous soil engineering 'services during the earthwork
operations. This is' to observe' compliance with the design concepts,
specifi'cations'or recommendations and to allow' design. changes in the event
that subsurface conditions differ from those anticipated prior to start of
construction.
UNIFORMITY OF CONDITIONS
S The recommendations and opinions, expressed in this report reflect our best
estimate of the project requirements based on an evaluation of the
subsurface soil' conditions encountered at the subsurface exploration
locations and the assumption that the soil conditions do not deviate
appreciably from those encountered. It should be recognized that the
performance of the foundations and/or cut and fill slopes may be influenced
by undisclosed or unforseen variations in the soil' conditions that may
occur in the intermediate and unexplored areas. Any unusual conditions not
S covered in this report that may be encountered during site development
should be brought to the attention of the soils engineer so that he -may
make modifications if necessary.
SCS&T 8521118 June 6, 1985 Page 9
CHANGE IN SCOPE
This office should be advised of any changes in the project scope or
proposed site grading so that it may be determined if the recommendations
contained herein are appropriate. This should be verified in writing or
modified by a written addendum.
TIME LIMITATIONS
The findings of this report are valid as of this date. Changes in the
condition of a property can, however, occur with the passage of time,
whether. they be due to natural processes or the work of man on this or
adjacent properties. In addition, changes in the State-of-the-Art.and/or
Government Codes may occur. Due to such changes, the findings of this
report may be invalidated wholly or in part by changes beyond our control.
Therefore, this report should not be relied upon after a period of two
years without a review by us verifying the suitability of the conclusions
and recommendations.
PROFESSIONAL STANDARD
0
In the performance of our professional services, we comply with that level
of care and skill ordinarily exercised by members of our profession
currently practicing under similar conditions and in the same locality.
The client recognizes that subsurface conditions may vary from those
encountered at the locations where our borings, surveys,, and explorations
are made, and. that our data, interpretations, and recommendations are based
solely an the information obtained by us. We will be responsible for those
data,*
-
interpretations, and recommendations, but shall not be responsible
for the interpretations by others of the information developed. Our
services consist of professional consultation and observation only, and no
warranty of any kind whatsoever, express or implied, is made or intended in
connection with the work performed or to be performed by us, or by our
proposal for' consulting or other services, or by our furnishing of oral or
written reports or findings.
. SCS&T 8521118 June 6, 1985 Page 10
CLIENT'S RESPONSIBILITY
It is the responsibility of B. A. Worthing, or his representatives to
ensure that the information and recommendations contained herein are
brought to the attention of the engineer and architect for the project and
incorporated into the project's plans and specifications. It is further
his responsibility to take the necessary measures to insure that the
contractor, and his subcontractors carry out such recommendations during
construction.
FIELD EXPLORATIONS
Five subsurface explorations were made at the locations indicated on the
attached Plate Number 1 on May 24, 1985. These explorations consisted of
trenches dug by means of a backhoe. The field work' was conducted under the
observation of our geology personnel .
The explorations were carefully logged when made. These logs are presented
on the following Plate Numbers 3 through 7. The soils are described in
accordance with the Unified Soils Classification System as illustrated on
the attached simplified chart on Plate 2. In addition, a verbal textural
descriptiOn, the wet color, the apparent moisture and 'the density or
consistency are presented. The density of granular materials is given as
either very 'loose, loose, medium dense, dense or very dense. The
consistency of silts or clays are given as either very soft, soft,, medium
stiff, stiff, very stiff., o.r'hard.
Disturbed and "undisturbed" samples of typical and representative soils
were obtained and returned to the laboratory for testing.
LABORATORY TESTING
Laboratory tests were performed in accordance with the generally accepted
American Society for Testing and Materials (A.S.T.M.) test methods or
suggested procedures. A brief 'description of the tests performed is
presented 'below: • . . . '
SCS&T 8521118 June 6, 1985 Page 11
a) MOISTURE-DENSITY: Field moisture content and dry density were
determined for representative undisturbed samples obtained. This
information was an aid to classification and permitted
recognition of variations in material consistency with depth.
The dry unit weight is determined in pounds per cubic foot, and
the field moisture content is'détermined as a percentage of the
soil's dry weight. The results are summarized iti the trench
logs.
.
b') CLASSIFICATION: Field classifications were verified in the
laboratory by visual examination. The final soil
classifications' are in accordance with the Unified Soil
Classification System. '
• c) DIRECT SHEAR TESTS:. Direct shear 'tests were performed to
determine 'the failure envelope based on yield shear strength.
The. shear box was designed toaccomodate a sample having
diameters of 2.375 inches or 2.50 inches and a height of 1.0
inch. Samples were tested at different vertical loads' and a
saturated moisture content. The shear'stress was applied at a
constant rate of strain of approximately 0.05 inches per minute.
The 'results of these tests are presented on attached Plate
Number 8.
n
d) COMPACTION TEST: The maximum dry density and optimum moisture
content of typical soils were •determined 'in the laboratory in
accordance with A.S.T.M. Standard Test D-1557-78, Method.1\. The
results of these tests are presented on the attached Plate
No. 8. ' •
LM
1. COARSE GRAINED, More than
half of material is larger
than No. 200 sieve size.
GRAVELS CLEAN GP.-\VELS
More than half of
coarse fraction is
larger than No. 4
sieve size but
smaller than 3' GRAVELS WITH FINES
(Appreciable amount
of fines)
SANDS CLEAN SANDS
More than half of
coarse fraction is
smaller than No. 4
sieve size. SANDS WITH FINES
(Appreciable amount
of fines)
11. FINE GRAINED, More than
half of material is smaller
than No. 200 sieve size.
SILTS-AND CLAYS
Liquid Limit
less than 50
SILTS AND CLAYS
O
SUBSURFACE EXPLORAT I ON LEGEND
UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION GROUP SYMBOL TYPICAL NINES
cw Well graded qravels, gravel-
sand mixtures, little or no
fines.,
GP- - Poorly graded gravels, gravel'
sand mixtures, little or no -
fines.
GM Silty gravels, poorly graded
gravel-sand-silt mixtures.
GC Clayey gravels, poorly
graded gravel-sand, clay
mixtures.
SW Well graded sand,gavelly
sands, little or no fines.
SP- Poorly graded sands,gravelly
sands, little or no fines.
SM Silty sands, poorly graded
'sand and silt mixtures.
Sc Clayey sands, pàorly graded
sand and clay mixtures.
ML Inorganic silts and very
fine sands, rock flour, sandy
silt or clayey-silt-sand
mixtures with slight plast-
icity
CL Inorganic clays of lci to
medium plasticity, gravelly
clays, sandy clays,silty
clays, lean clays.
OL Organic silts and organic
silty clays of low plasticity
MH Inorganic silts, micaceous
or diatomaceous fine sandy
or silty soils, elastic
silts.
Liquid Limit CH Inorganic clays of high
greater than 50 plasticity, fat clays.
OH Organic clays of medium
to high plasticity.
HIGHLY ORGANIC SOILS PT Peat and other highly
organic soils.
- Water level at time of excavation or as indicated
US - Undisturbed, driven ring sample or tube sample
CK - Undisturbed chunk sample -
BG -'Bulk sample
SOUTHERN CALIFORNIA
SOIL & TESTING , INC.
8280. PIVERDALE STREET
SAN DIEQO, CALIFORNIA 2120
BY RRR DATE 6-7-85
LI I . ' JOB NO.
L 8521118. Plate No. 2
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SM Brown, SILTY SAND
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12- . SLIGHTLY SILTY SAND - - Dense
— (Sandstone)
92.6 1 -6.5 I 72 -
98.7 I 7.5 I 76
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SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG
SOIL & TESTUG,8C.
LOGGED BY: G. S. DATE LOGGED: 5-24-85
JOB NUMBER: 8521118 - Plate No. 3
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SAMPLE TYPE
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SAMPLE DESCRIPTION
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T-4 @ 3.5 Undisturbed 31 300
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MAXIMUM DENSITY and OPTIMUM MOISTUR CONTENT
ASTM_1557-78 METHOD _A
SAMPLE
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maximum
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T-1 @2-4 Brown Silty Sand 129.1. 9.5
BY RRR DATE 6-6-85
JOB NO. 8521118 Plate NO. 8
LOTS 3 AND 6-8,MAP 10870
RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS
GENERAL-'INTENT
The intent of these specifications is to establish procedures for clearing,
compacting natural ground, preparing areas to. be filled, and placing and
compacting fill soils to the lines and grades shown on the accepted plans.
The recommendations contained in the preliminary, soil investigation report
and/or the attached Special Provisions are a part of the Recommended
Grading Specifications and shall supei-sede the provisions contained
hereinafter in the case of conflict. These specifications shall only be
used in conjunction with the soil report for whih they are a part. . No
deviation from these specifications will be allowed, except where specified
in the soil report or in other written communication signed by the Soil
Engineer.
OBSERVATION AND TESTING
Southern California Soil and Testing, Inc., shall be retained as the Soil
Engineer to observe and test the earthwork in accordance with these
specifications. it will be necessary that the Soil Engineer or his
representative provide adequate observation so that he may provide an
opinion that the work was or was not accomplished as specified. It shall
be the responsibility of the contractor to assist the soil engineer and to
keep him apprised of work schedules, changes and new information and data
so that he may provide these opinions. In the event that any unusual
conditions not covered by the' special provisions or preliminary soil report
are encountered during the grading operations, the Soil Engineer shall be
contacted for further' recommendations.. •
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SCS&T 8521118 June 6, 1985 . Appendix, Page 2
If, in the opinion of the Soil Engineer, substandard conditions are
encountered, such as; questionable or i unsuitable soil, unacceptable
moisture content, inadequate compaction, adverse weather, etc., he will be
empowered to either to either stop construction until the conditions are
remedied or -corrected or recommend rejection of this work.
Test methods used to determine the degree of compaction should be. performed
in accordance with the following American Society for Testing and Materials
test methods: . . . . . .
Maximum Density & Optimum Moisture Content - A.S.T.M. 0-1557-78.
Density of Soil In-Place - A.S.T.M. D-1556-64 or A.S.T.M. D-2922.
All densities shall be expressed in terms of Relative Compaction as
determined by the foregoing A.S.T.M. testing procedures.
PREPARATION OF AREAS TO RECEIVE FILL
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All vegetation, brush and debris derived from clearing operations
shall be removed, and legally disposed of. all areas disturbed by site
grading should be left in a neat and finished appearance, free from
41 unsightly debris.
Any abandoned buried structures encountered during grading operations must
be total ly-'removed. All underground utilities to be abandoned beneath any
proposed structure should be. removed from within 10 feet of the structure
and properly capped off. The resulting depressions from the above
described procedures should be backfilled with acceptable soil that is
compacted to the requirements of the Soil Engineer. This includes, but is
not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm
SCS&T 8521118 June 6, 1985 Appendix, Page 3
drains and water lines. Any buried structures or utilities not to be
abandoned should be investigation by the Soil Engineer to determine if any
special recommendation will be necessary.
All water wells which will be abandoned should be backfilled and capped in
accordance to the requirements set forth in the Geotechnical Report. The
top of the cap should be at least 4 feet below finish grade or 3 feet below
the bottom of footing whichever is greater. The type of cap will depend on
the diameter of the well and should be determined by the Soil Engineer
and/or a qualified Structural Engineer.
When the slope of the natural ground receiving fill exceeds 20% (5
horizontal units to 1 vertical unit), the original ground shall be stepped
or benched. Benches shall be cut to a firm competent soil condition. The
lower bench shall be at least 10 feet wide or 1 1/2 times the the equipment
width which ever is greater and shall be sloped back into the hillside at a
gradient of not less than two (2) percent. All other benches should be at
least 6 feet wide. The horizontal portion of each bench shall be compacted
prior to receiving fill as specified hereinbefore for compacted natural
ground. Ground slopes flatter, than 20% shall be benched when considered
necessary by the Soil Engineer.
After clearing or benching, the natural ground in areas to be filled shall
be scarified to a depth of 6 inches, brought to the proper moisture
content, compacted and tested for the minimum degree of compaction in the
Special Provisions or the recommendation. contained in the preliminary soil
investigation report. All loose soils in excess of 6 inches thick should
be removed to firm natural ground which-, is defined as natural soils which
possesses an in-situ density of at least 85% of its maximum dry density.
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SCS&T 8521118 June 6, 1985 Appendix, Page 4
FILL MATERIAL
Materials placed in the fill shall be approved by the soil engineer and
shall be free of vegetable matter and other deleterious, substances.
Granular soil shall contain sufficient fine material to fill the voids.
The, definition and disposition of oversized rocks, expansive and/or
detrimental soils are covered in the soils report or Special Provisions.
Expansive soils,, soils of poor gradation, or soils;with low strength
characteristics may be thoroughly mixed with other soils. to provide
satisfactory fill material , but only with the explicit consent of the soil
engineer. . Any import material shall be approved by the Soil Engineer
before being brought to the site.
PLACING AND COMPACTION OF FILL
Approved fill material shall be placed in areas prepared to receive fill in
layers not to exceed 6 inches in 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..',.Each layer shall be uniformly compacted to a minimum specified
degree of compaction with equipment of adequate size 'to economically
compact the layer. Compaction equipment should either be 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, recommendations contained in the preliminary soil investigation '
report. ,
When the structural fill material includes rocks, no rocks will be allowed
to nest and all voids must be carefully filled with soil such that the
minimum degree of' compaction recommended in the Special Provisions is
SCS&T 85211-18 June 6, 1985 Appendix, Page 5
achieved. The maximum size and spacing of rock permitted I in structural
fills and in non-structural fills is discussed in the soil report, when
applicable.
Field observation and compaction tests to estimate 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. When the compaction test indicates that a particular layer is.
less than the required degree of compaction, the layer shall be reworked to
the satisfaction of the Soil Engineer and until the desired relative
compaction has been obtained.
Fill slopes shall be compacted by means of sheepsfoot rollers or other
suitable equipment. compaction by sheepsfoot rollers shall be at vertical
intervals of not greater than four feet. In addition, fill slopes at
ratios of -two horizontal to one vertical, or flatter, should be 'trackrolled.
Steeper fill slopes shall be over-built and cut-back to finish contours.
Slope compaction operations shall result in all fill material six or more
inches inward from the finished face .of the slope having a relative.
compaction of-at least 90% of maximum dry density or' that specified in the
Special Provisions section of thisspecification. The compaction operation
on the slopes shall be continued until the Soil Engineer is satisfied' that
the slopes will be stable in regards to surficial stability.
Slope tests will be made by the Soils Engineer during construction of the
slopes to determine if the required compaction is being achieved. Where
'failing tests occur. or other field problems arise,.the Contractor will be
notified that day of such conditions by written communication from the Soil
Engineer in the form of a daily field report. .
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SCS&T 8521118 June 6, 1985 Appendix, Page 6
If the method of achieving, the required slope compaction selected by the
Contractor fails to produce the necessary results, the Contractor shall
rework or rebuild such slopes until the required degree of compaction is
obtained, at no additional cost to the Owner or Soils Engineer.
CUT SLOPES
The Engineering Geologist shall inspect all cut slopes excavated in rock or
lithified formational material during the grading operations at intervals
determined at his discretion. If any conditions not anticipated in the
preliminary report such as perched water, •seepage, lenticular or confined
strata of a potentially adverse nature, unfavorably inclined bedding,
joints or fault planes are encountered during grading, these conditions
shall be analyzed by the Engineering Geologist and Soil Engineer to
determine if mitigating measures and necessary.
Unless otherwise specified in the soil and geological report, no cut slopes
shall be excavated higher or steeper than that allowed by the. ordinances of
the controlling governmental agency.
ENGINEERING OBSERVATION
Field observation by the soil Engineer or his representative shall be made
during, the filling and compacting operations so that he can express his
opinion regarding the conformance of the grading with acceptable standards'
of practice. The presence of the Soil Engineer or his representative or
the observation and testing shall not release the Grading Contractor from
his duty to compact all fill material to the specified degree of
compaction.
SCS&T 8521118 June 6,. 1985 Appendix, Page 7
SEASON LIMITS
Fill shall not be placed during unfavorable weather conditions. When work
is interrupted by heavy rain, filling operations shall not be resumed until
the proper moisture content and density of the fill materials. can. be
achieved. Damage site cdnditions resulting from weather or acts of God
shall b repaired before acceptance of work. .' . .
RECOMMENDED GRADING,SPECIFICATIONS - SPECIAL PROVISIONS
The minimum degree of compaction to be obtained 'in compacting natural
ground, in the compacted fill, and in the compacted backfill shall be at
least 90 percent.
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Detrimentally 'expansive so i.1 is defined as soil which will swell more
than 3' percent against •a pressure of. 150 pounds per square foot from a
condition of 90 percent of maximum dry density and air dried moisture
content to saturation.
Oversized fill material is defined as rocks or lumps. over 6 inches in
diameter. At least 40 percent of the fill soils shall pass through a No. 4
U.S. Standard Sieve.
TRANSITION LOTS: Where transitions between cut and fill occur within the
proposed building pad, the cut 'portion. should be undercut a minimum of one
foot' below the base of the proposed footings and recompacted as structural
backfill. ' 0