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. ~~ SO!JI1lERN CALIFORNIA
'W SOIL & TESTING, INc.
6280 Riverda1e Street, San Diego, CA 92120
P.o. Box 600627, San Diego, CA 92160-0627
619-280-4321, FAX 619-280-4717
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February 20, 1997
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. SERV\CtGS&T 97 11041
ENG\oNEER\~~C\N\í!\S Report No.1
CiTY OF ~
Patrick and Michele Timmins
3303 Calle del Sur
Carls bad, California 92009
SUBJECT:
GTading Plan Review and Geotechnical Update, Lot #14, Brookside Residential
Subdivision, City of Encillitas 4376, City ofEncillitas, California.
REFERENCE:
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Dear Mr, and Mrs. Timmins:
In accordance with your request, we have reviewed the grading plan prepared for the subject site by Rick
Vandervort, Arclùtect, dated February 6, 1997, and our previous reports pertaining to the site, and
observed the lot. in its present condition. The purpose of our grading plan review was to verify that our
recommendations for site grading had been incorporated in the plan. Our review of previous geotechnical
reports was done for the purpose of updating our recommendations based upon changed site conditions or
standards of practice.
GRADING PLAN REVJEW
We found that the grading plan was prepared in accordance with our recommendations for earthwork, as
presented in the referenced report.
UPDATED RECOMMENDATIONS
EARTHWORK: Lot #14 is in an essentially unaltered condition from the date of the referenced report.
Our recommendations for site preparation remain unchanged
FOUNDATIONS AND INTERIOR FLOOR SLAB
GENERAL: The configuration of the proposed residence will result in both the upper dwelling and lower
garage footings sparming fill soils with depth differentials on the order of twelve feet, over a relatively short
lateral distance. In order to lessen the potential for distress that could result from differential settlement of
the fills, we recommend that the foundations and slabs be stiffened. Our revised foundation
recommendations are as follows:
FOOTINGS: Conventional spread footings may be used to support the proposed two-story structure.
Provided the building pads are capped with at least three feet of nondetrimentally expansive soil (expansive
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SCS&T 9711041
February 20, 1997
Page 2
index less than 50), footings should be fOlmded 18 inches below lowest adjacent finish grade. Continuous
and isolated footings should have a minimum width of 12 and 18 inches, respectively. Continuous footings
should be reinforced with at least four No.5 bars, two near the top and two near the bottom of the footings.
An allowable soil bearing pressure of 2500 psf may be used for design.
ANTICIPATED SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential
settlements for the proposed structure may be considered to be within tolerable limits provided the
recommendations presented in this report are followed. It should be recognized that minor cracks nonnally
occur in concrete slabs and fOlmdations due to shrinkage during curing or redistribution stresses and some
cracks may be anticipated. Such cracks are not necessarily an indication of excessive vertical movements.
INTERIOR FLOOR SLAB: The interior floor slab should have a minimum thickness of four inches.
Reinforcing should consist of at least No.3 bars at 18 inches on center each way. The on-grade interior
slab should be underlain by one inch of sand over 6 mil visqueen over three inches of coarse, clean sand,
pea gravel, or crushed rock. If the coarse clean sand is used, it should have a gradation such that less than
10 percent passes the standard # 100 sieve size.
SOJL EXPANSION POTENTIAL: It is anticipated that the foundation soils will be non-detrimentally
expansive. The above recommendations reflect this condition.
RETAINING WALL PARAMETERS
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 yield at the top (unrestrained walls). For earth retaining structures that are fixed at the top
(restrained walls), an equivalent fluid pressure of 50 pounds per cubic foot may be used for a design
parameter. For backfill that slopes upward from the top of walls at a 2:1 and a 1.5:1 slope, the above
pressures should be increased by 13 and 25 pounds per cubic foot, respectively. The above pressures for
restrained and non-restrained walls do not consider any other surcharge loading. If any other surcharge
loadings are anticipated, this office should be contacted for the necessary change in soil pressure. this
value also assumes granular and drained backfill conditions.
PASSIVE PRESSURE: The passive pressure for prevailing soil conditions may be considered to be 400
pounds per square foot of depth up to a maximum pressure of 2500 psf. The upper 12 inches of soil
should not be considered when computing passive pressures. This pressure may be increased one-third for
seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.35 for the
resistance to lateral movement. When combining frictional and passive resistance, the friction value should
be reduced on one-third.
BACKFILL: All backfill soils should be compacted to at least 90% relative compaction. Expansive or
clayey soils should not be used for backfill material within a distance of five feet from the back of the wall.
the retaining structure should not be backfilled until the materials in the wall have reached an adequate
strength.
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SCS&T 9711041
February 20,1997
Page 2
F ACTOR OF SAFETY: The above values, with the exception of the concrete-soil friction coefficient, do
not include a factor-of-safety. Appropriate factors-of-safety should be incorporated into the design of all
earth retaining structures to reduce the possibility of overturning and sliding.
If you should have any questions after reviewing this report, please do not hesitate to contact this office.
This opportunity to be of professional service is sincerely appreciated.
Respectfully Submitted,
Reviewed by:
Charles H. Christian, RGE #00215
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SUMMARY OF FIELD OBSERVATIONS AND
TESTS FOR RELATIVE COMPACTION
MASS GRADING OPERATION
PROPOSED TIMMINS RESIDENCE, LOT #14
CITY OF ENCINITAS TRACT NO. 4376
3256 BROOKSIDE LANE
OLIVENHAIN, CALIFORNIA
\~[ (~~
"JL MAY 20 1997
ENGINEERING SER~J:riES
CiTY OF ENC!NIl 1\:;
PREPARED FOR:
PATRICK AND MICHELLE TIMMINS
3303 CALLE DEL SUR
CARLSBAD, CALIFORNIA 92029
PREPARED BY:
SOUTHERN CALIFORNIA SOIL AND TESTING, INc.
6280 RIVERDALE STREET
SAN DIEGO, CALIFORNIA 92120
Providing Professional Engineering Services Since 1959
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~ SOUTHERN CALIFORNIA
'q/ SOIL & TESTING, INc.
6280 Riverda1e Street, San Diego, CA 92120
PO. Box 600627, San Diego, CA 92160-0627
619-280-4321, FAX 619-280-4717
May 16, 1997
Patrick and Michelle Timmins
3303 Calle Del Sur
Carlsbad, California 92029
SCS&T 9711041
Report No.2
SUBJECT:
Summary of Field Observations and Tests for Relative Compaction, Mass
Grading Operation, Proposed Timmins Residence, Lot #14, Brookside
Residential Subdivision, City of Encinitas Tract No. 4376, 3256 Brookside Lane,
Olivenhain, California.
REFERENCE:
"Grading Plan Review and Geotechnical Update, Lot #14, Brookside Residential
Subdivision;" Qy Southern California Soil and Testing, Inc., dated February 20,
1997, 9711041-1.
Dear Mr. and Mrs. Timmins:
In accordance with your request, this report has been prepared to summarize the results of field
observations and tests for relative compaction performed at the subject site by Southern California
Soil and Testing, Inc. These services were performed between May 6 and 12, 1997.
SITE DESCRIPTION
The project site is identified as Lot #14, Brookside Residential Subdivision, of the City of Encinitas
Tract No. 4376 and is located at 3256 Brookside Lane in Olivenhain, California. The subject site
is bounded by Brookside Lane to the west, Lot #11 to the north, Lot #15 to the south, and
undeveloped land to the east. Prior to grading,the subject site was comprised of a moderately
sloping hillside with an elevation change of approximately 40 feet. The hillside sloped down from
the east to the west. Vegetation consisted of a moderate growth of native grasses and shrubs.
PROPOSED CONSTRUCTION
It is our understanding that the subject site is being developed to receive a single family residence
of wood-frame construction consisting of an upper and lower dwelling. An elevation change of
approximately lO-feet will exist between the two attached dwellings. Shallow foundations and
conventional slab-on-grade floor systems are anticipated. Underground utilities and associated
hardscape paving are also proposed for construction.
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SCS&T 9711041
May 16, 1997
Page 2
A V AILABLE PLANS
To assist in determining the locations and elevations of our field density tests and to define the
general extent of the site grading for this phase of work, we were provided with a grading plan
prepared by Rick Vandervort, Architect, bearing an approval date by the City Engineer of April
22, 1997.
SITE PREPARATION
GRADING CONTRACTOR: The earthworking operations addressed in this report were
performed by Terra-Movers, Inc. of Escondido, California; CA License No. A-553475.
Equipment utilized during the grading work consisted of a Caterpillar 08 crawler dozer, a
Caterpillar 988 rubber tire loader and a water hose.
LOT GRADING: In accordance with our recommendations, the existing topsoil and alluvial
deposits were removed in the area influenced by the proposed building pad and areas to receive
fill. The bottoms of the removals typically exposed soils consisting of metavolcanic bedrock. In
the area of the building pad, the removals extended laterally approximately five feet beyond the
perimeter of the building. Fill soils were then taken from the material generated from the removals
and on-site cuts and was placed in the removal areas. Typically, fill soils were placed in thin,
moisture conditioned lifts and compacted to at least 90 percent of maximum dry density until
designed elevations were reached. Compaction was achieved by means of a Caterpillar 988 rubber
tire loader and heavy construction equipment.
KEYWAYS: Where determined necessary to provide adequate support for the proposed fills, the
original ground had a keyway cut to competent metavolcanic bedrock. Keyways were constructed
at the toes of the slopes located at the southwestern property line at the western side of the building
and at the southern side of the building. The approximate lateral extents of the keyways
constructed are as noted on the attached Plate Number 1. The keyways were typically at least 15
feet wide and sloped back into the hillside at an approximate gradient of two percent. As the
height of the fill increased, the existing hillside was benched, exposing competent soils for the
support of the proposed fills.
FILL SLOPES: During construction of the fill slopes, fill was placed in thin lifts as previously
described and the faces of the slopes were compacted in vertical increments typically not exceeding
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SCS&T 9711041
May 16, 1997
Page 3
four feet. The fill slopes were compacted by means of a Caterpillar 08 crawler dozer. Upon
completion, the slopes were again track-walked to further compact the slope faces and to provide
a uniform surface.
CUT/FILL TRANSITION:
Transitions between cut and fill material occurred within the
northeast corners of the upper and lower dwellings of the proposed structure. In order to create
a uniform soil condition beneath the proposed structure and to lessen the potential for differential
settlement, the cut portions of the structure were overexcavated to a depth of approximately three
feet below finished pad grade. Subsequent to the overexcavations, the resulting excavations were
filled with uniformly compacted fill material until designed elevations were reached and in the
manner previously described.
FIELD OBSERVATION AND TESTING
Field observation and density tests were performed by a representative of Southern California Soil
and Testing, Inc. during the mass grading operations. The density tests were taken according to
ASTM 02922-91 (nuclear gauge). The results of those tests are shown on the attached plates. The
accuracy of the in-situ density test locations and elevations is a function of the accuracy of the
survey control provided by other than Southern California Soil and Testing, Inc. representatives.
Unless otherwise noted, their locations and elevations were determined by pacing and hand level
methods and should be considered accurate only to the degree implied by the method used.
As used herein, the term "observation" implies only that we observed the progress of work we
agreed to be involved with, and performed tests, on which, together, we based our opinion as to
whether the work essentially complies with the job requirements, local grading ordinances and the
Uniform Building Code.
LABORATORY TESTS
Maximum dry density determinations were performed on representative samples of the soils used
in the compacted fills according to ASTM 01557-91, Method A. This method specifies that a four
(4) inch diameter cylindrical mold of 1/30 cubic foot volume be used and that the soil tested be
placed in five (5) equal layers with each layer compacted by twenty-five (25) blows of a lO-pound
hammer with an 18-inch drop. The results of these tests, as presented on Plate Number 2, were
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SCS&T 9711041
May 16, 1997
Page 4
used in conjunction with the field density tests to determine the degree of relative compaction of
the compacted fill.
REMAINING WORK
Additional grading and backfill operations will be required for the backfilling of utility trenches
and retaining walls and the preparation of the subgrade and base material placement in the
pavement areas. It is recommended that field observations and relative compaction tests be
performed during these operations to verify that these operations are performed in accordance with
job requirements and local grading ordinances.
CONCLUSIONS
Based on our field observations and the in-place density test results, it is the opinion of Southern
California Soil and Testing, Inc. that the grading work was performed substantially in accordance
with the recommendations contained in the referenced report, the City of Encinitas grading
ordinance, and the Uniform Building Code. Recommendations for the minimum design of
foundations, as presented in the referenced report, remain applicable and for ease of reference,
have been reproduced below.
FOUNDATIONS AND INTERIOR FLOOR SLAB
GENERAL: The configuration of the proposed residence will result in both the upper dwelling
and lower garage footings spanning fill soils with deep differentials on the order of twelve feet,
over a relatively short lateral distance. In order to lessen the potential for distress that could result
from differential settlement of the fills, we recommend that the foundations and slabs be stiffened.
Our revised foundation recommendations are as follows:
FOOTINGS: Conventional spread footings may be used to support the proposed structure. The
footings should be founded 18 inches below lowest adjacent finish pad grade. Continuous and
isolated footings should have a minimum width of 12 and 18 inches, respectively. Continuous
footings should be reinforced with at least four No.5 bars, two near the top and two near the
bottom of the footings. An allowable soil bearing pressure of 2500 psf may be used for design.
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SCS&T 9711041
May 16, 1997
Page 5
SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential settlements for
the proposed structure may be considered to be within tolerable limits provided the recommenda-
tions presented in this report are followed. It should be recognized that minor cracks normally
occur in concrete slabs and foundations due to shrinkage during curing or redistribution of stresses
and some cracks may be anticipated. Such cracks are not necessarily an indication of excessive
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vertical movements.
INTERIOR FLOOR SLAB: The interior floor slab for the lower pad should have a minimum
thickness of four inches and should be reinforced with at least No.3 bars at 18 inches on center
each way. For the upper slab, the minimum slab thickness recommended is five inches. Minimum
slab reinforcement in this case is No.3 bars at 12 inches on center each way. Slab reinforcement
should extend at least six inches into perimeter footings. The on-grade interior slab should be
underlain by one inch of sand over 6 mil visqueen over three inches of coarse, clean sand, pea
gravel, or crushed rock. If the coarse clean sand is used, it should have a gradation such that less
than 10 percent passes the standard #100 sieve size.
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SOIL EXPANSION POTENTIAL: It is anticipated that the foundation soils will be nondetrimen-
tally expansive (expansion index less than 50). The above recommendations reflect this condition.
FOUNDATION EXCA VA TION OBSERVATIONS: All footing excavations should be observed
by a member of our engineering/geology staff to verify that the foundation excavations extend into
a suitable bearing stratum.
LIMITATIONS
This report covers only the services performed between May 6 and 12, 1997. As limited by the
scope of the services which we agreed to perform, our opinion presented herein is based on our
observations and the relative compaction test results. Our service was performed in accordance
with the currently accepted standard of practice and in such a manner as to provide a reasonable
measure of the compliance of the mass grading operations with the job requirements. No
warranty, express or implied, is given or intended with respect to the services which we have
performed, and neither the performance of those services nor the submittal of this report should
be construed as relieving the contractor of his responsibility to conform with the job requirements.
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SCS&T 9711041
May 16, 1997
Page 6
If you should have any questions regarding this report, please do not hesitate to contact this office.
This opportunity to be of professional service is sincerely appreciated.
Respectfully submitted,
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
DBA:DH:GET:mw
cc: (4) Submitted
I JOB NAME: TIMMINS RESIDENCE JOB NO: 9711041
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IN--PLACEDENSITY TESTS I
I ELEVATION MOISTURE DRY DENSITY SOIL REL. COMPo
TEST DATE LOCATION (feet, MSL) (percent) (p.d.) TYPE (percent)
1 5/6/97 Building Lot - West Slope 127.0 10.4 116.9 3 95.7
I 2 5/6/97 Building Lot - West Slope 129.5 11.2 118.7 3 97.1
3 5/6/97 Building Lot - West Slope 131.0 11.0 117.8 3 96.4
4 5/6/97 Building Lot - West Slope 128.5 10.8 116.2 3 95.1
I 5 5{7/97 Driveway 128.5 12.7 115.4 3 94.4
6 5{7/97 Driveway 131.5 11.6 114.9 3 94.0
7 5{7/97 Driveway 132.5 10.1 116.6 3 95.4
I 8 5{7/97 West Side of Building Pad 139.5 11.7 117.4 3 96.1
9 5{7/97 West Side of Building Pad 141.0 12.9 119.0 3 97.4
10 5/8/97 Garage Pad 137.0 11.4 119.1 4 96.2
I 11 5/8/97 Slope Southeast of Garage 141.0 12.6 115.4 4 93.2
12 5/8/97 Slope Southeast of Garage 143.5 10.6 119.7 4 96.7
13 5/8/97 West of Building Pad 140.0 10.1 117.1 4 94.6
I 14 5/8/97 West of Building Pad 142.0 10.7 119.2 4 96.3
15 5/8/97 West of Building Pad 142.5 11.6 119.8 4 96.8
16 5/9/97 Building Pad 145.0 12.2 118.7 4 95.9
I 17 5/9/97 South of Building 146.0 13.8 116.1 4 93.8
18 5/9/97 North of Building 144.5 12.4 116.7 4 94.3
19 5/9/97 North of Building 147.0 12.0 118.0 4 95.3
I 20 5/9/97 Building Pad 147.0 11.8 119.2 4 96.3
21 5/12/97 Driveway F.G. 131.0 10.4 116.0 4 93.7
I 22 5/12/97 Driveway F.G. 135.0 11.2 116.4 4 94.0
23 5/12/97 Garage Pad F.G. 138.0 12.9 115.6 4 93.4
24 5/12/97 Building Pad F.G. 148.0 10.1 122.7 4 99.1
I 25 5/12/97 Building Pad F.G. 148.0 9.9 118.4 4 95.6
26 5/12/97 See Plate 1, Back Yard F.G. 147.5 8.5 113.6 4 91.8
27 5/12/97 See Plate 1, Front Yard F.G. 148.0 10.9 116.8 4 94.3
I 28 5/12/97 See Plate 1, Driveway F.G. 132.5 11.9 114.5 4 92.5
29 5/12/97 See Plate 1, Driveway F.G. 133.5 10.2 116.1 4 93.8
30 5/12/97 See Plate 1, Driveway F.G. 137.5 11.0 117.9 4 95.2
I 31 5/12/97 See Plate 1, Driveway Berm F.G. 132.0 10.8 116.4 4 94.0
32 5/12/97 See Plate 1, Driveway Berm F.G. 136.0 9.8 114.8 4 92.7
33 5/12/97 See Plate 1, Driveway Berm F.G. 139.0 10.7 117.3 4 94.7
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I MAXIMUMDENSrrYAND . OPTIMUM MOISTURE SUMMARY (ASTM D 1557) I
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SOIL TYPE SOIL DESCRIPTION OPTIMUM MOISTURE, % MAXIMUM DENSITY, pcf
I *3 Brown Sand with Clay 9.8 122.2
*4 Orange/Brown, Silty Sand 12.8 123.8
* Maximum dry density values obtained from "Report of Field Observations and Relative Compaction Tests, Proposed
I Brookside Subdivision;" by Southern California Soil and Testing, Inc., dated November 28, 1989,8821115-9.
PLATE NO: 2
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