2003-7544 G/CS W
CHRISTIAN WHEELER
E N G.LN
E
April 19, 2002 I #
U0
Soil Testers _ __ ._.J CWE 202.048.1
Post Office Box 1195 J
Lakeside, CA 92040
SUBJECT: SEISMIC.DESIGN CRITERIA, PROPOSED RESIDENTIAL BUILDING
SITE, 252 DUBLIN DRIVE, ENCINITAS, CALIFORNIA
REFERENCES: 1) Site Inspection, Proposed Residential Building Site, 252 Dublin Drive, Cardiff Area,
Cityof Encinitas, California by Soil Testers, File No. 10360, dated April 3, 2002.
2) Maps of Known Active Fault Near - Source Zones in California and Adjacent
Portions of Nevada by California Division of Mmes and Geology, dated February
1998.
3) Geologic Maps of the Northwestern Part of San Diego County, California;
California Division of Mmes and Geology Open -File Report 96 -02 by Siang S. Tan
and Michael P. Kennedy
Dear Ladies and Gentlemen:
In accordance with your request, we have prepared this letter to present pertinent seismic /geotechnical
information regarding the project site. The setpe of our limited study consisted of a review of the
referenced soils report, a review of other pertinent literature, and the preparation of this letter that includes
our findings.
GENERAL GEOLOGIC SETTING: The project site is located in the Coastal Plains Physiographic
Province of San Diego County and is underlain by Tertiary-age and Quaternary-age sediments, associated
surficial soils, and artificial fill. The near - surface materials at the site are described in the referenced report
by Soil Testers.
SEISMIC DESIGN PARAMETERS: Based on a maximum magnitude (Mmax) earthquake of 6.9 along
the nearest portion of the Rose Canyon Fault Zone, the Maximum Bedrock Acceleration at the site would be
approximately 0.38 g. For structural design purposes, a damping ratio not greater than 5 percent of critical
dampening, and Soil Profile Type Sc are recommended (UBC Table 16 -J). Based upon the location of the site
at approximately 4 kilometers from the Rose Canyon Fault Zone (Type B Fault), Near Source Factors N,
equal to 1.10 and N. equal to 1.33 are also applicable. These values, along with other seismically related design
4925 Mercury Street ♦ San Diego, CA 92111 f 858- 496 -9760 + FAX 858- 496 -9758
CWE 202.048 April 19, 2002 2
parameters from the Uniform Building Code (UBC) 1997 edition, Volume II, Chapter 16, utilizing a Seismic
Zone 4 are presented in tabular form below.
UBC— CHAPTER 16 SEISMIC RECOMMENDED
TABLE No. PARAMETER VALUE
16 Seismic Zone Factor Z 0.40
16-J Soil Profile Type Sc
16-Q Seismic Coefficient Q 0.44 N
16-R Seismic Coefficient C, 0.64 N„
16-S Near Source Factor Na 1.10
16-T Near Source Factor N,. 1.33
16-U Seismic Source Type B
LIQUEFACTION: Liquefaction is the phenomenon that may result in large total and/or differential
ground surface settlement and possible lateral ground spreading during an earthquake. Liquefaction occurs
when loose, saturated, generally fine sands and silts are subject to strong ground shaking. The soil loses all
shear strength and becomes a viscous liquid for a short period of time, and then usually solidifies.
Settlement of the ground surface and failure of foundations caused by liquefaction is usually only affected
by the soils that liquefy within the upper 30 feet; the effect of liquefaction of soils below this depth is not
usually manifested at the ground surface. Four conditions usually must be present before liquefaction can
occur:
1) The soil is below the groundwater table, i.e., saturated;
2) The soil is composed predominantly of fine sand and silt;
3) The soil is in a loose to medium dense state;
4) The soil is subject to a sufficient magnitude and duration of strong ground shaking.
Based on the available information, it appears that the ground water table is relatively deep and that the
native materials at the site below the foundation elevation are generally medium dense to dense and are not
subject to liquefaction.
If you have any questions after reviewing this letter, please do not hesitate to contact this office.
Respectfully submitted,
CHRISTIAN WI EELER ENGINEERING c
Nc. 1 a C i
!� j
CERTIFIED
ENiF�: E"' I NG o
,I GEOLOGIST
Curtis R Burdett, C.E.G. # 1090 �� U�> Exp. 10 -02
CRB:crb
cc: (4) Submitted ` ��� C ����
* * * * * * * * * * * * * * * * * * * * * **
* *
* E Q F A U L T
* *
* Version 3.00
* *
* * * * * * * * * * * * * * * * * * * * * **
DETERMINISTIC ESTIMATION OF
PEAK ACCELERATION FROM DIGITIZED FAULTS
JOB NUMBER: 202.048
DATE: 04 -19 -2002
JOB NAME: 252 Dublin Drive, Cardiff
CALCULATION NAME: Dublin Drive Analysis
FAULT- DATA -FILE NAME: CDMGFLTE.DAT
SITE COORDINATES:
SITE LATITUDE: 33.0176
SITE LONGITUDE: 117.2774
SEARCH RADIUS: 100 mi
ATTENUATION RELATION: 2) Boore et al. (1997) Horiz. - NEHRP C (520)
UNCERTAINTY (M= Median, S= Sigma): M Number of Sigmas: 0.0
DISTANCE MEASURE: cd_2drp
SCOND: 0
Basement Depth: 5.00 km Campbell SSR: Campbell SHR:
COMPUTE PEAK HORIZONTAL ACCELERATION
FAULT -DATA FILE USED: CDMGFLTE.DAT
MINIMUM DEPTH VALUE (km): 0.0
--------- - - - - --
EQFAULT SUMMARY
--------- - - - - --
-----------------------------
DETERMINISTIC SITE PARAMETERS
-----------------------------
---------------------------------------------------------------------------
(ESTIMATED MAX. EARTHQUAKE EVENT
APPROXIMATE 1-------------------------------
ABBREVIATED I DISTANCE MAXIMUM 1 PEAK JEST. SITE
FAULT NAME mi (km) IEARTHQUAKEI SITE JINTENSITY
MAG.(Mw) 1 ACCEL. g 1MOD.MERC.
------------------------
ROSE CANYON 2.4( 3.9)1 _6.9 1 0.382 I X
NEWPORT - INGLEWOOD (Offshore) 1 13.0( 20.9)1 6.9 1 0.155 VIII
CORONADO BANK 1 17.0( 27.4)1 7.4 1 0.165 VIII
ELSINORE - JULIAN 1 29.0( 46.7)1 7.1 1 0.094 1 VII
ELSINORE - TEMECULA 1 29.2( 47.0)) 6.8 1 0.080 1 VII
EARTHQUAKE VALLEY 1 41.9( 67.4)1 6.5 1 0.052 1 VI
PALOS VERDES 1 42.4( 68.3)1 7.1 1 0.070 1 VI
ELSINORE -GLEN IVY 1 43.4( 69.9)1 6.8 1 0.059 1 VI
SAN JACINTO -ANZA 1 51.8( 83.4)1 7.2 1 0.063 VI
ELSINORE- COYOTE MOUNTAIN 1 53.1( 85.5)1 6.8 1 0.050 1 VI
SAN JACINTO- COYOTE CREEK 53.9( 86.8)1 6.8 1 0.050 VI
SAI4 JACINTO-SAN JACINTO VALLEY 1 54.1( 87. "1) 1 6_9 1 0.052 1 VI
NEWPORT- INGLEWOOD (L.A.Basin) 1 55.3( 89.0)1 6.9 0.052 1 VI
CHINO - CENTRAL AVE. (Elsinore) 1 57.1( 91.9)1 6.7 1 0.055 1 VI
WHITTIER 1 61.5( 98.9)1 6.8 1 0.045 1 VI
SAN JACINTO - BORREGO 1 64.0( 103.0)1 6.6 1 0.039 1 V
COMPTON THRUST 1 64.9( 104.4)1 6.8 1 0.053 1 VI
ELYSIAN PARK THRUST 1 68.3( 109.9)1 6.7 1 0.048 VI
SAN JACINTO -SAN BERNARDINO 1 69.0( 111.1)1 6.7 1 0.039 1 V
SAN ANDREAS - San Bernardino 1 72.2( 116.2)1 7.3 1 0.052 1 VI
SAN ANDREAS - Southern 1 72.2( 116.2) 7.4 1 0.055 1 VI
SAN ANDREAS - Coachella 1 78.1( 125.7)1 7.1 1 0.044 1 VI
SAN JOSE 1
1 78.2( 125.9)1 6.5 1 0.039 1 V
SUPERSTITION MTN. (San Jacinto) i 78.5( 126.4)1 6.6 1 0.034 1 V
PINTO MOUNTAIN 1 78.7( 126.7)1 7.0 1 0.041 1 V
CUCAMONGA 1 80.9( 130.2)1 7.0 1 0.049 1 VI
SIERRA MADRE 1 81.0( 130.3)1 7.0 1 0.049 1 VI
ELMORE RANCH 1 82.5( 132.7)1 6.6 1 0.032 1 V
BURNT MTN. 1 82.6( 133.0)1 6.4 1 0.029 1 V
LAGUNA SALADA 1 83.3( 134.1)1 7.0 1 0.040 1 V
SUPERSTITION HILLS (San Jacinto) 1 83.4( 134.2)1 6.6 1 0.032 1 V
NORTH FRONTAL FAULT ZONE (West) 1 84.4( 135.9)1 7.0 1 0.048 1 VI
EUREKA PEAK 1 85.4( 137.4)1 6.4 1 0.028 i V
CLEGHORN 1 86.9( 139.8)1 6.5 1 0.029 1 V
NORTH FRONTAL FAULT ZONE (East) 1 87.6( 140.9)1 6.7 1 0.039 1 V
RAYMOND 1 89.9( 144.7) 1 6.5 1 0.035 V
CLAMSHELL - SAWPIT 1 90.3( 145.4)1 6.5 1 0.035 i V
SAN ANDREAS - 1857 Rupture 1 90.5( 145.7)1 7.8 1 0.056 1 VI
SAN ANDREAS - Mojave 1 90.5( 145.7)1 7.1 1 0.039 1 V
VERDUGO 1 92.2( 148.4)1 6.7 1 0.038 1 V
LANDERS 1 93.5( 150.5)1 7.3 1 0.042 1 VI
BRAWLEY SEISMIC ZONE 1 93.8( 150.9)1 6.4 1 0.026 1 V
HOLLYWOOD ( 94.0( 151.3)1 6.4 i 0.032 1 V
HELENDALE - S. LOCKHARDT 1 96.4( 155.2)1 7.1 1 0.037 1 V
SANTA MONICA 1 98.5( 158.5)1 6.6 1 0.034 1 V
IMPERIAL 1 99.4( 159.9)1 7.0 1 0.034 1 V
LENWOOD - LOCKHART -OLD WOMAN SPRGSI 99.5 ( 160.2)1 7.3 1 0.040 1 V
-END OF SEARCH- 47 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS.
THE ROSE CANYON FAULT IS CLOSEST TO THE SITE.
IT IS ABOUT 2.4 MILES (3.9 km) AWAY.
LARGEST MAXIMUM- EARTHQUAKE SITE ACCELERATION: 0.3815 g
I S401L TEETERS ho
P.O. Box 1195
Lakeside, California
April 3, 2002 92040
(619) 443 -0060
Gary Myron
P.O. Box 838
Cardiff, California 92007
SUBJECT: File No. 10360 E
SITE INSPECTION i
Proposed Residential Building Site
252 Dublin Drive I
Cardiff area, City of Encinitas t
L__ _.
Dear Mr. Myron:
SCOPE
In accordance with your request, a Site Inspection has been performed at the subject site. The
purpose of this investigation was to examine existing site conditions and provide engineering
recommendations for the proposed residential structure. It is our understanding that the
project will consist of a two -story, single family residential structure.
FIELD INSPECTION
In order to accomplish this purpose, a representative of this firm visited the site, reviewed the
topography and site conditions and visually and textually classified the surface and near
surface soils. Representative samples of the on -site soils were obtained from a test
exploration approximately 3 feet in depth and tested for density, shear strength and expansive
characteristics. An in -place field density test was taken in the bottom of the test exploration in
accordance with A.S.T.M. D1556 -82. The test results indicate relative compaction of the
native soils at approximately 3 feet in depth is 87.4 percent A hand -held auger was used to
drill to approximately 7 feet in depth.
SITE CONDITIONS
The subject site is a small residential property located on the northwest corner of Dublin
Drive and Manchester Avenue in an older established neighborhood. The site is presently
occupied by an older single- family residence and two storage sheds with chain link fencing
around the majority of the perimeter. It is our understanding that these structures will be
1
Traci Tolman File No. 10360 April 3, 2002
removed to make way for the proposed new development. The parcel is located on the
southerly side of a hill and sits approximately 4 feet above Manchester Avenue. The site is
relatively level from the alley on the north side to the south side of the rear shed and then
slopes towards Manchester Avenue in small terraces. The adjacent property to the west is
also occupied by a single- family residence. Vegetation consists of small trees in the backyard
terraced garden. Man made fill soils were encountered to approximately 3 feet in depth in the
test exploration. A one -inch gas line was encountered in the test exploration.
SOIL CONDITIONS
The soils encountered in the test exploration were fill materials consisting of brown, slightly
clayey, silty fine to medium sands with pieces of paper, plastic, charcoal etc. to approximately
1.5 feet in depth. The surface soils were underlain by brown, silty fine to medium sands with
charcoal, glass pieces and small roots (also fill) to approximately 3 feet in depth. The native
soils underlying the fill was very firm, very moist, tan sand and grey clay to approximately
4.5 feet in depth where tan sand with a small amount of clay was encountered. The sand
extended to the bottom of the boring, approximately 7 feet in depth.
The sandy soils encountered in the test exploration were not considered to be detrimentally
expansive with respect to change in volume with change in moisture content (Expansion
Index (14).
Some clayey soils were observed and it is possible that more clayey material could be
exposed during the proposed grading operation. If more expansive material is encountered
during grading, the foundation recommendations in this report will be amended in the Report
of Compacted Filled Ground to reflect the final soil conditions.
CONCLUSIONS AND RECOMMENDATIONS
1. In order to provide uniform support for the proposed structure, the existing fill soils
in proposed building areas should be excavated to firm natural ground
(approximately 3 feet in depth), replaced and recompacted to 90 percent
compaction in accordance with the following Grading Specifications. The
recompaction should extend at least 5 feet outside the proposed building footprint.
Any organics such as tree roots trash, or other deleterious material that may be
encountered should be removed prior to recompaction.
2. Conventional spread footings founded a minimum of 12 inches below lowest adjacent
grade and having a width determined by the allowable soil bearing value as detailed
above are recommended for foundation support. Footing widths should be at least 12
inches for continuous footings and 24 inches for square footings due to practical
2
Gary Myron File No. 10360 April 3, 2002
considerations as well as Building Code requirements. This footing design is a
minimum based upon the foundation soil type and does not take into consideration
structural requirements.
3. Reinforcing in footings should consist of at least one #4 steel bar placed continuously
in the top and bottom of continuous footings regardless of structural requirements.
Reinforcing for isolated footings are dictated by the structural requirements. These
recommendations are based upon on the soil type encountered and do not take into
consideration the proposed bearing load.
4. Concrete slabs -on -grade should be constructed to have a nominal thickness of 4" and
underlain with a sand blanket of 3 inches in thickness. Provide minim temperature
reinforcement consisting of 6X6 -10/10 welded wire mesh. The sand subbase (sand
blanket) should have a sand equivalent exceeding 30 per ASTM D2419. All slabs
should either have a conventional thickened edge or be poured monolithically with
continuous footings at the slabs perimeter. Conventional thickened edges should be
8" thick at slab edge, uniformly tapering to 4" thick at 2' from slab edge. The
thickened edges or monolithic footings should extend completely around the slab's
perimeter. Construction and expansion joints should be considered slab edges.
Maximum spacing of expansion joints is 50' for interior slabs and 30' for exterior
slabs.
5. A representative sample of the foundation soil was remolded to 90% of maximum
dry density (125.9). Based on the following test results, a safe allowable bearing
value of at least 2500 pounds per square foot may be used in designing the
foundations and slab for the proposed structure. This value may be increased by
one third for wind and/or seismic loading.
Angle of internal friction 36°
Cohesion 192 psf
Unit weight 112.8 pcf
6. Resistance to horizontal movement may be provided by allowable soil passive
pressure and/or coefficient of friction of concrete to soil. The allowable passive
pressure may be assumed to be 200 psf at the surface and increasing at the rate of 400
psf per foot of depth. These pressures assume a frictionless vertical element, no
surcharge and level adjacent grade. If these assumptions are incorrect, we should be
contacted for values that reflect the true conditions. The values are for static
conditions and may be increased 1/3 for wind and/or seismic loading. The coefficient
of friction of concrete to soil may be safely assumed to be 0.5.
3
Gary Myron File No. 10360 April 3, 2002
7. Active pressures for the design of unrestrained, cantilevered, individually supported
retaining walls, capable of slight movement away from load may be considered to be
equivalent to the pressures developed by a fluid with a density of 34 pcf. This value
assumes a vertical, smooth wall and level drained backfill. We should be contacted for
new pressures if these assumptions are incorrect. Restrained walls, incapable of
movement away from load without damage such as basement walls, should be designed
for the additional equivalent fluid of 27 pcf applied triangularly for cohesionless type
soils and trapezoidally for cohesive type soils.
8. The above design values and foundation design assume that the retaining wall
excavation will expose soils similar to those we tested during our site inspection.
We should inspect the cut to insure that the soils exposed are the same as those
we tested.
RECOMMENDED GRADING SPECIFICATIONS
For
Proposed Residential Building Site
252 Dublin Drive
Cardiff area, City of Encinitas
GENERAL: Soil Testers and 'Soil Engineer' are synonymous hereinafter and shall be
employed to inspect and test earthwork in accordance with these specifications, the accepted
plans, and the requirements of any jurisdictive governmental agencies. They are to be allowed
adequate access so that the inspections and tests may be performed. The Soil Engineer shall
be appraised of schedules and any unforeseen soil conditions.
Substandard conditions or workmanship, inadequate compaction, adverse weather, or
deviation from the lines and grades shown on the plans, etc., shall be cause for the soil
engineer to either stop construction until the conditions are corrected or recommend rejection
of the work. Refusal to comply with these specifications or the recommendations and/or
interpretations of the soil engineer will be cause for the soil engineer and/or his representative
to immediately terminate his services.
Deviations from the recommendations of the Soil Report, from the plans, or from these
Specifications must be approved in writing by the owner and the contractor and endorsed by
the soil engineer.
SOIL TEST METHODS:
Maximum Density & Opt Moisture -- ASTM D1557 -70
Density of Soil In -Place -- ASTM D1556, D2922 and D3017
Soil Expansion -- UBC STANDARD 29 -2
4
Gary Myron File No. 10360 April 3, 2002
Shear Strength -- ASTM D3080 -72
Gradation & Grain Size -- ASTM D1140 -71
Capillary Moisture Tension -- ASTM D2325 -68
Organic Content -- % Weight loss after heating for 24 hours
at 300° F and after deducting soil moisture.
LIMITING SOIL CONDITIONS:
Minimum Compaction 90% for 'disturbed' soils. (Existing fill,
newly placed fill, plowed ground, etc.)
84% for natural, undisturbed soils.
95% for pavement subgrade within T of
finish grade and pavement base course.
Expansive Soils Expansion index exceeding 20
Insufficient fines Less than 40% passing the #4 sieve.
Oversized Particles Rocks over 10" in diameter.
PREPARATION OF AREAS TO RECEIVE FILL:
Brush, trash, debris and detrimental soils shall be cleared from the areas to receive fill.
Detrimental soils shall be removed to firm competent soil. Slopes exceeding 20% should be
stepped uphill with benches 10' or greater in width. Scarify area to receive fill to 6" depth and
compact.
FILL MATERIAL shall not contain insufficient fines, oversized particles, or excessive
organics. On -site disposition of oversized rock or expansive soils is to be at the written
direction of the Soil Engineer. Select fill shall be as specified by the soil engineer. All fills
shall be compacted and tested
SUBDRAINS shall be installed if required by and as directed by and detailed by the soil
engineer and shall be left operable and unobstructed. They shall consist of 3" plastic
perforated pipe set in a minimum cover of 4" of filter rock in a 'vee' ditch to intercept and
drain free ground from the mass fills. Perforated pipe shall be schedule 40,
Poly - Vinyl- Chloride or Acrylonitrile Butadienne Styrene plastic. Rock filter material shall
conform to the following gradation:
Sieve size: 3/4" #4 #30 #200
%Passing: 90 -100 25 -50 5 -20 0 -7
Subdrains shall be set at a minimum gradient of 0.2% to drain by gravity and shall be tested
by dye flushing before acceptance. Drains found inoperable shall be excavated and replaced.
CAPPING EXPANSIVE SOILS: If capping expansive soils with non - expansive soil to
5
Gary Myron File No. 10360 April 3, 2002
mitigate the expansive potential is used, the cap should be compacted, non - expansive, select
soil placed for a minimum thickness 3' over the expansive soil and for a minimum distance of
8' beyond the exterior perimeter of the structure. Special precautions should be taken to
ensure that the non - expansive soil remains uncontaminated and the minim thickness and
dimensions around the structure are maintained. The expansive soils underlying the cap of
non - expansive cap should be pre - saturated to a depth of 3' to obtain a degree saturation
exceeding 90% before any construction supported by the compacted cap.
The non - expansive soil comprising the cap should conform to the following:
Minimum Compaction 90%
Maximum Expansion Index 30
Minimum Angle of Internal Friction 33 Deg
Cohesion Intercept 100 psf
UNFORESEEN CONDITIONS: Soil Testers assume no responsibility for conditions
which differ from those described in the applicable current reports and documents for this
property. Upon termination of the soil engineer's services for any reason, his fees up to the
time of termination become due and payable. If it is necessary for the soil engineer to issue an
unfavorable report concerning the work that he has been hired to test and inspect, the soil
engineer shall not be held liable for any damages that might result from his 'unfavorable
report'.
If we can be of any further assistance, please do not hesitate to contact our office. This
opportunity to be of service is sincerely appreciated.
Respectfully submitted,
OQ POFESS /p
C.
A
wrt NO, 21,650 m
�os h C. 9myth, RCE 2145V EXP. 9130/05
s CIVIL �Q
JCS/ss 4rF of CAL%f
6